Monday, June 4, 2012

The Last Battleship

Over the Memorial Day weekend, USS Iowa left San Francisco Bay, presumably for the last time,on its way to become a historical exhibit in, apparently, San Pedro. (She should have become a historical exhibit here, in San Francisco. That she didn't is a travesty for which the political side I generally agree with was to blame, but has roots in an episode that was not the Navy's best moment. See the Wikipedia page on the ship. But watching her leave was a rather moving experience I otherwise would not have had.)

I am not sure in what sense Iowa is the 'last battleship.' It does not seem to have been the very last in commission, but more likely was the last to be 'striken' from the navy list. This came after it rusticated for some years in the Suisun Bay mothball fleet, out of commission but at least nominally available for refurbishment and return to service. (In fact, it seems that even as a museum ship it is in some theoretical sense still available. But its next berth will almost certainly be its last.)

By exquisite coincidence Iowa passed under the Golden Gate Bridge on the day before the bridge's 75th anniversary celibration, and also happened to coincide with the commemoration of Memorial Day, the 'Murrican counterpart to Remembrance Day.

It all lends itself to any number of reflections. Swords and plowshares: After a lifetime of honorable service (70 years since launch, less a few months), Iowa is headed for a twilight afterlife as a waterfront exhibit, while the bridge remains a major regional traffic artery.

The transience of grandeur: The battleship era still conveys a powerful image, but it was remarkably brief, and Iowa's career belongs almost entirely to its epilogue. None of its class was ever seriously tested as a battleship, i.e. in action against enemy battleships.

In World War II the Iowas were used primarily as carrier escorts. During the Cold War era they were periodically recommissioned for offshore fire support. Functionally they were no longer capital ships, though size and impressiveness certainly qualified them for maintaining a presence, one of the most fundamental naval missions.

The first battleship is considerably harder to identify. The last generation of sailing 2-deckers and 3-deckers were called 'line of battle ships' in place of the older 'ships of the line.' But this usage disappeared when ironclads came along.

The first generation of ironclads had an amazing variety of armament layouts and general configurations. No one knew what the capital ship of the future would be like, which gives the era a wonderfully steampunkish flavor. Russia's Admiral Popov was a radical design even for the era, but shows how unsettled the design possibilities were.

By the 1880s the more bizarrely creative designs were set aside. A relatively standard type of capital ship emerged, exemplified by HMS Royal Sovereign, laid down 1889, and the term 'battle ship' came into use to describe them.

Today we mainly know them as pre-dreadnoughts. Let us pause to admire the meta-ness of that term. Pre-dreadnoughts ruled the waves for a generation, but for nearly all of that time absolutely no one thought of them as 'pre-dreadnoughts.' Our ideas about these ships are inevitably filtered through their successors, and for half the battleship era retrospective time flows backward.

The last engagement between battleships - there were never very many - was Surigao Strait in 1944, so that the battleship era lasted just 55 years. If we take Pearl Harbor as the end of battleship supremacy, 52 years. Thus the battleship epilogue, exemplified by Iowa's career, lasted considerably longer than the battleship era itself did.

In fact the battleship era was transitory, not really an 'era' at all. This may be kept in mind when thinking - and most of you are inevitably thinking - of battleships' possible future spacegoing counterparts. Relatively short periods can stand out in our minds and become nearly timeless 'eras,' when in fact they only lasted a few decades.

That said, in an an age of post-industrial technological maturity the overall configuration of capital vehicles might be as stable as it was in the age of sail.

Capital vehicles - how is that for a colorless expression? I have argued before in this blog, more than once, that the familiar and time-honored naval analogy may be misleading when it comes to space forces. Laser stars, as I have speculated about them, have only a fairly tenuous similarity to 'battleships.' If kinetics are dominant, the platforms from which they are deployed might be even more remote from the battleship image.

On the other hand, the similarities might turn out to be greater, if only because impressive weapon systems have power-political significance that extends well beyond their purely military characteristics.

Discuss.




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My phone camera image of Iowa passing under the Golden Gate Bridge was too low-res to be worth posting. The Tumblr image above comes from this naval history page.

1,169 comments:

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Tony said...

Re: afterburners and emergency maneuvering.

Dudes...we're talking about a notional vehicle that masses several hundred tons. It maneuvers like a bus. By the time you reorient to execute your dodge, the time for dodging is done. If you just dodge in the direction you happen to be pointing, a homing KKV won't have any trouble compensating.

For all realistic maneuvers, you only need a few tenths of a G. Adding LOX for increased thrust is an inefficient use of your mass budget.

Byron said...

Locki:
I never agreed that hitting a spacecraft would be difficult. Your contention, based on the hit rate of an unspecified ABM, fails to take into account hardware maturity. Unless there are a significant number of cases where the missile functions properly, but still fails to hit, there is no basis for claiming spacecraft are difficult targets.

Tony said...

Byron:

"Locki:
I never agreed that hitting a spacecraft would be difficult. Your contention, based on the hit rate of an unspecified ABM, fails to take into account hardware maturity. Unless there are a significant number of cases where the missile functions properly, but still fails to hit, there is no basis for claiming spacecraft are difficult targets."


Actually, I think this is one of the big unknowns. Terminal homing KKVs will certainly have fast enough computers to process the data in time to use it. The question is whether mechanical maneuvering systems can operate quickly enough and with enough precision to apply the necessary corrections. I could see spinning KKVs equipped with popcorn thrusters rather than a non-spinning KKV equipped with the traditional X and Y axis thrusters. The reason is that single-impulse thrusters can be made very quick acting and relatively precise in the amount of impulse they deliver. Also, a spinning body does not have to use component X + Y thrusting; it just has to wait until a useable thruster rotates around to the proper orientation.

TOM said...

Hmm, i see.

What if i turn well before the missile arrives, then use the main engines?
I dont have to face at the direction that i fly.

http://en.wikipedia.org/wiki/AIM-120_AMRAAM

This claims :

"Operationally, the missile, which was designed for beyond visual range combat, has a Pk of 46% when fired at targets beyond visual range (13 missiles for 6 kills). In addition, the targets lacked missile warning systems, were not maneuvering, and were not attempting to engage the fighter that fired the AMRAAM. "

Tony said...

TOM:

"Hmm, i see.

What if i turn well before the missile arrives, then use the main engines?
I dont have to face at the direction that i fly."


I said "pointing", not "moving" for this specific reason. And it doesn't matter when you reorient. Once the KKV gets close, you can only change vector in the direction your nose is pointed. If you thrust when the missile is far enough away, you give it time to correct. If you thrust in the last few seconds, you just don't move much, even at three Gs. You would only move 1,500 meters after ten seconds of constant thrust.

The KKV should be able to make that correction, even at dozens of KPS. Let's give our KKV a 50 kps relative velocity. Let's further say it has to make it's final correction one second out. At that point, the KKV sees you moving along a new vector that it has presumable already corrected for. How much further does your target spacecraft travel, at 3 Gs of acceleration, than the KKV has already corrected for? 15 m. If it has a biased proportional law guidance algorithm that can recognize acceleration, it will hit you dead center anyway.

Now, hitting within say 5m from 50 km may sound like crazy high precision, but it's only a tenth of a mil. Infantry mortarmen and tank gunners are taught to achieve 1 mil precision. I'm pretty sure even relatively inexpensive instrumentation can do better than that.

TOM said...

http://www.ausairpower.net/TE-Evading-Missiles.html

I also found this one.

What if the targeted craft can blind or damage the missile, so it will be unable to home? Then you still have to dodge.

Tony said...

TOM:

"http://www.ausairpower.net/TE-Evading-Missiles.html

I also found this one."


All of the observations and techniques mentioned in that article are based on fighting in an atmosphere at relatively slow speeds, with the target more maneuverable than the incoming missile. I don't think any of that is applicable in space, except perhaps for IR background clutter (e.g. planet in same FOV as target, WRT KKV point of view).

"What if the targeted craft can blind or damage the missile, so it will be unable to home? Then you still have to dodge."

I would think that would be tried. But it's kind of hard to do anything to a KKV at more than 1,000 km beyond overload its sensors. And even that takes a lot of energy. Also, a KKV may be designed to keep its sensors shuttered until the last ten or so seconds. Then blinding becomes a matter of engaging specific KKVs, which makes it harder to account for them all.

WRT to necessary defensive maneuvering, well, the KKVs have probably been dumped by a bus into a pattern that makes defensive maneuvering in any direction no good. Your best bet is countermissiles and Whipple shields to absorb the debris.

TOM said...

I see.

Then rough equivalent of present day fast attack craft, missile boats, patrol boats, with a major difference, they dont suffer from lack of seaworthyness.
(But still depend on mothership for non orbital voyages.)

I guess SF like fighters have to rely on recoilless spacetime warp drives at least...

Tony said...

TOM:

"I see.

Then rough equivalent of present day fast attack craft, missile boats, patrol boats, with a major difference, they dont suffer from lack of seaworthyness.
(But still depend on mothership for non orbital voyages.)"


Their biggest handicaps would be life support endurance, followed by general vulnerability to attack. On the other hand, you can have more of them, which means the enemy has to divide his attentions.

"I guess SF like fighters have to rely on recoilless spacetime warp drives at least..."

Wouldn't hurt. But even in that case one has to generate the power for the drive somehow. And Newtonian physics still applies at this scale. You may be able to accelerate at 100 Gs without smearing the crew, but the enemy can build the same capability into his missiles.

Anonymous said...

Tony,

For all realistic maneuvers, you only need a few tenths of a G. Adding LOX for increased thrust is an inefficient use of your mass budget.

==========

However adding LOX for thrust + allowing for Combustion Gas gun would likely be more mass efficient than having a coil gun, a way to make the electricity for said coil gun (using the NTR presumably) and all the extra radiators to do that.

Especially since the Combustion Gas Gun has some increased capacity at short gun lengths -- and you could get some extra thrust - that you may never need.

-------

Would probably be most efficient to use missiles only and not use the NTR for making electricity.

But the LTR is even more efficient in that sense - no reactor,less radiators, no reactor shielding

-------
One last point - it is possible to design a NTR with more than 1G of thrust with no added LOX. Nerva isn't the maximum potential of the design - nor was it the best for thrust/mass of the proposed designs at the time it was tested.

Not that you would need that perfromance either.

(SA Phil)

Anonymous said...

TOM,

I guess SF like fighters have to rely on recoilless spacetime warp drives at least...

==========

That and super batteries since you can generate massive amounts of power with no need for radiators or reactor shielding or a reactor even.

And a surrounding bubble of special atmosphere moving in direct opposition relevant to the craft that you can't see or breathe but you can use to manuever the fighter.

(SA Phil)

Thucydides said...

For the research challenged among us, I offer this page from "Atomic Rockets" with everything you could need to know about lasers. Please note the theoretical maximal capabilities of a RBoD; it can engage tagets with deadly effect to one light hour, once you make the assumption that targeting (with a cloud of sensors) and precision beam aiming (using some unspecified magitech) is possible:

http://www.projectrho.com/public_html/rocket/spacegunconvent.php

"Direct drive" nuclear pumped lasers were mooted several hundred posts back; here is the scoop on them:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790014704_1979014704.pdf

Incidentally, does anyone know where Luke Campbell is now. I'd hate to think of him experimenting in his basment laser lab....

Rick said...

One important note on KKVs - it is easier to hit big targets than small ones. Even Tony's 'fighters' are large spacecraft - several hundred tons, IIRC.

Their physical dimensions must be on the same order as transport class aircraft, naval corvettes, or heavy lift lower stages. Target cross section must be 100x greater than a missile warhead RV.

That said, the toughest challenge for KKVs is probably precision targeting. And the higher the closing speed the tougher the job: You're farther from the target when you must make that last critical correction burn.


A note on laser boost - if you have this technology you can surely have laser stars, because the requirements are rather similar. You need to dump a lot of energy onto a small area of surface a long ways from the laser.

Anonymous said...

Thucydides said...

For the research challenged among us, I offer this page from "Atomic Rockets" with everything you could need to know about lasers. Please note the theoretical maximal capabilities of a RBoD; it can engage tagets with deadly effect to one light hour, once you make the assumption that targeting (with a cloud of sensors) and precision beam aiming (using some unspecified magitech) is possible:
============================

The accuracy section is (essentially) pasted below for sake of discussion - credit goes of course to atomic rockets .. and Dr. Shilling.

=====================
Off the top of his head, Dr. John Schilling mentions:

*Uncertain target location due to finite sensor resolution
*Uncertain target motion due to sensor glint or shape effects
*Sensor boresight error due to finite manufacturing tolerances
*Target motion during sensor integration time
*Analog-to-digital conversion errors of sensor data
*Software errors in fire control system
*Hardware errors in fire control system
*Digital-to-analog conversion errors of gunlaying servo commands
*Target motion during weapon aiming time
*Weapon boresight error due to finite manufacturing tolerances
*Weapon structural distortion due to inertial effects of rapid slew
*Weapon structural distortion due to external or internal vibration
*Weapon structural distortion due to thermal expansion during firing

And we haven't even begun to include target countermeasures...
=======================

Unfortunately I do not see anywhere in the section (which I have read on numerous occasions before today) how they anticipate accurate *targeting* to light minutes -- only theoretically deadly power densities. And that is on the section of X-Ray lasers.

How would the cloud of sensors work exactly? Would they be *much* closer than light minutes and act as forward observers for the laser? Or some other mechanism?

(SA Phil)

Anonymous said...

Rick,


A note on laser boost - if you have this technology you can surely have laser stars, because the requirements are rather similar. You need to dump a lot of energy onto a small area of surface a long ways from the laser.
=========

heh I was thinking of it the other way - If you have Laser-Stars, you suddenly have economical space travel.

And more mass thrifty missiles, "fighters", etc, etc.

Chicken or the Egg?

Maybe one technology would drive the other - so in the quest for an economic space industry you get a better defense force which in turn drives your space industry...

You start with Laser Boost to orbit ... along the way are Laser Stars and Laser Thermal Craft of all sizes ... and you end up with Laser-Sail driven interstellar craft.

(SA Phil)

Locki said...

Engineering types correct me if I'm wrong because my analysis always seemed a bit simplistic to me.

Does an automatic evasion pretty much always occur if the maximum accelleration of the of the target (say 2G with LOX injected into a NTR) exceeds the maximum accelleration of the missile (say 1G).

Is it that easy to work out?

Re Byron on targetting fast moving targets:

I think we could reasonably assume hitting a faster target is a LOT harder than hitting a smaller target. There are limitations on the mechanical maneuver systems of the missile to ensure you can thread the missile through that exact predicted point in space at the exact predicted time. Eg with a 3kps closing speed to hit a 2m target you will need to predict the place that target will be given your predicted flight time and then thread that missile through that point in a time accurate to 0.00067seconds. It ain't easy to achieve that incredible precision at 500+ km when you are using a fixed thrust, constant on solid booster rocket and little puffs of air to maneuver.

Anonymous said...

I suppose I always imagine the missile would aim/point/move directly at the target the entire time with as close to a direct vector as it could manage.

So its more like they portray "ramming speed" than some kind of aeronautical display.

As closing speed went up - your missile DeltaV/accel would probably also need to go up to make the correct timely vector changes.

The target is going to have a hard time affecting a vector the missile cant reach while simultaneously affecting a vector the other missiles in the KKV cloud can't reach.

Doesn't do you much good to dodge one missile if the 25 behind it can adjust to your jinking.

(SA Phil)

Locki said...

The accuracy section is (essentially) pasted below for sake of discussion - credit goes of course to atomic rockets .. and Dr. Shilling.

(SA Phil)


=====

I studied atomic rockets for more than a year before posting on rocketpunk. It is an incredible resource for any aspiring hard SF author.

For targetting issues with lasers you could add in its inability to "adjust/correct" its aim on the fly.

If you do miss the target (for any of the myriad above reasons) you don't know if you went high, low, right or left becauase you can't actually see your own laser beam in a vacuum. So if your alignment or targetting algorithms are out for any sort of reason you can't "strafe" your laser into the target like the Shadow Battlecrabs did in B5.

This is in marked contrast to a cannon or missile. I know there were a couple of earlier suggestions about how to overcome this (defocus then refocus) but really I don't think even this method, if it could work, would tell if the laser is high or right etc.

Thucydides said...

The cloud of sensors is the easy part, you are basically creating an optical interferometer with an arbitrarily large baseline and resolution. There are several projects underway to have satellites flying in high precision formation to do just that as astronomical instruments, so it would be safe to say that this technology would be well understood by the time you could build a laserstar of any size.

For a RBoD, you would probably want the cloud to extend one light second in every direction from the position of the laserstar itself, so the maximal time delay is .5 second while the picture is building. Given enough sensors in the cloud, you would have the ability to create a fairly detailed 3D model of the surrounding space during your approach or while doing surveillance; your picture would start to degrade once the engagement is opened as the enemy attempts to take out as many sensors as possible.

As for hitting a target, the maximal figures posted in the Atomic Rockets site are just that. If a RBoD xaser can be focused down to 5mm at one light second, it does not mean you need to have your spot that small. I would gladly accept a 30m spot at one light second, and even perhaps "rastering" the beam in order to ensure a hit (the target would most certainly light up in the IR wavelength when that much energy is deposited on it).

Since almost any PMF system will take many hours minimum to cross that distance, the RBoD will have lots of opportunity to dazzle, scorch or even kill targets from a long way out. Once again, Rick worked out the overkill ratio in one of the earlier Space War posts; the RBoD would need to be overmatched by something on the order of 10,000 SCoDs in order to achieve a kill.

The problem could be even harder if we assume powerful lasers with precision pointing are used as laser thermal launchers; the fireing rate could be a lot higher with massive thermal sinks and if the launcher is supported by platoons of fighting mirrors, then the oncoming cloud of KKV's is essentially flying into the blast of a flamethrower. The only compensating factor is the laser launcher will most likely use a much longer wavelength to maximize heat transfer to the friendly spacecraft's remass, so your range is cut down to fractions of a light second and your scorch/dazzle ranges are also correspondingly shorter. The use of mirrors limits the laser's frequency to the UV range, high UV and xasers need diffraction gratings to steer the beam.

TOM said...

Re SF fighters :
Many SF designs have wings to serve as radiators, and also certain SFs employs Newtonian mechanics /as far as i know Yamato Babilon 5 BSG/.
With warp drives, you can have manueverability.

Return to PMF : well, unless there is some scaling issue, a missile can provide bigger acc than the ship, the question is rather to accuracy of the tracking thrusters.
Although i still wonder on dodging some bigger shrapnels, if you can shatter the missiles.

TOM said...

Tony : you spoke about 1/10 g acceleration.
But i guess peak acc with near empty tanks can be bigger, if the propellant has got the majority of the mass?
I would like to use theese crafts to deploy troops to a moon, or a planet with the help of aerobraking.

If i capture what i wanted, i find the way to send them back to orbit.

Samantha said...

Tom: A spaceship dodging a kinetic kill vehicle simply isn't going to happen. There are several reasons:

1) Spaceships need to carry, at minimum, a mission payload to be useful whereas KKVs do not. Therefore, KKVs can attain higher thrust-to-weight ratios.

2) Spaceships need to perform complex maneuvers/operate for extended periods of time/operate over long ranges to be useful whereas KKVs merely need to boost from their launch platform to their target one-way. Therefore, KKVs can sacrifice delta-V for thrust when spaceships cannot.

3) Because spaceships can only thrust in one direction efficiently their maneuvering is highly predictable. KKVs can simply aim off the bow of their target, cutting off their escape.

4) Are you really going to sit there dodging back and fourth with high-thrust engines? Do you have any idea how much reaction mass that would burn?!

Eth said...

On the other hand, the smaller scale may work against the KKV, and it has to use some of its propellant to accelerate.
Also, while the target has to accelerate at a greater rate than the KKV, it has to do so only for a brief time if it is done just before impact. Side thrusters may even be possible, if such short-duration high-thrust (and low-ISP) thrusters are simple and light enough.

I don't think dodging KKV swarms would be practical anyway, though ; it seems simpler to shoot them down with, say, lasers or CNoH.

About solar/laser sails, are there detailed models about their resistance against KKV or given laser wavelengths?

Locki said...

Re: Plausibility of KKV swarms.

Surely the mass limits of a militarised spaceship (eg less mass = more delta V) is just as critical as the payload of a fighter plane.

A space warship will probably only carry 4-8 KKVs like a warplane of today rather than the 128 VLS missile tube farms of a present day Aegis destroyer (where mass and weight are far less relevent than it is to a fighter or spaceship)

Byron said...

Targeting a spacecraft at high velocity has been done successfully at least thee times: the ASAT tests. All of them involved direct ascent (and thus high closing velocity) and hard kills on small targets. A spacecraft, even a gunboat (a term I prefer to fighter for that type of craft), is much larger.
Dodging a projectile would depend on how smart it is. A simple proportional navigation system can be defeated with higher acceleration at any time. A more sophisticated system might aim at the nose of the target to prevent last-minute acceleration, meaning you have to dodge earlier and harder.

Tony said...

Let's see...

KKV acceleration vs ship acceleration is irrelevant. We're already presuming a high closing velocity. If the ship is accelerating across the KKV field of view, the KKV has to be able to handle the angular rate of change, not match the acceleration in a given direction. If the KKV is coming bow- or stern-on, then it really doesn't matter. A ship simply isn't going to accelerate fast enough to make the necessary change in velocity to leave the KKV behind.

See, unlike Sidewinders or AMRAAMs, the KKV is not plowing through an atmosphere. It maintains it's energy without thrusting, and doesn't lose energy to drag.

Also, KKVs would probably not have individual rocket motors for acceleration. They would be sent out on a bus, using a single ICBM-sized motor. The bus would subsequently deploy several, maybe dozens, of KKVs at the optimum point in its trajectory.

WRT targeting, I made this point obliquely in an engagement analysis earlier, but I guess it needs to be made more explicitly. If you're trying to dodge, even at several Gs, don't expect to have much luck with it. If the KKV has to make its final correction at one second to predicted impact, you can only move your ship five meters per G you lay on. If you accelerate at 3 Gs, you move 15 meters. If you accelerate at 5 Gs, you move 25 meters. Also, it only takes 1/10 mil precision to hit within a 5 m circle from 50 km. If you're arriving at only 5 kps relative velocity -- much more likely than 50 kps, in the PMF -- one only needs 1 mil precision to hit within a 5 m circle. As stated earlier, that's the level of precision that modern ground troops regularly achieve in aiming their weapons, using reltively inexpensive optics.

Rick said...

If the ship is accelerating across the KKV field of view, the KKV has to be able to handle the angular rate of change, not match the acceleration in a given direction.

These converge on being the same thing. If at time zero the KKV and ship are on collision course, the question is whether the ship can sidestep more than the KKV can 'chase' it in the remaining time before impact or miss.

Tony said...

Rick:

"These converge on being the same thing. If at time zero the KKV and ship are on collision course, the question is whether the ship can sidestep more than the KKV can 'chase' it in the remaining time before impact or miss."

With a little bit of simple logic, the KKV can account for target acceleration. At five Gs, a ship can "sidestep" all of 2500 m in ten seconds. If the KKV has a 10 G maneuvering capability -- and why shouldn't it; modern air to air missiles have motors at least that powerful -- it can run a cycle of accelerate for half a second, observe, accelerate some more (if necessary), rinse, repeat. Or you can imagine any cycle you wish, given a known acceleration rate for your KKV.

The ship will also make a change in velocity of 0.5 kps. That's a lot of delta-v to miss just one KKV. And the KKVs are probably attacking in a pattern with various degrees of built-in "aim-off" to ensure that even if one gets beat at maneuvering, that just guarantees running into another.

Anonymous said...

The missile will almost certainly have better accel than the target - unless it is specifically designed to have minimum performance.

The final missile just has so much fewer mission parameters to worry about - its proportional mass budget is excellent.

And it can use chem rockets which give awesome acceleration.

You might have SCOD missiles with 10+Gs of final stage accel without too much trouble.

(SA Phil)

Rick said...

At five Gs, a ship can "sidestep" all of 2500 m in ten seconds. If the KKV has a 10 G maneuvering capability -- and why shouldn't it; modern air to air missiles have motors at least that powerful

I agree completely, but the question was whether the missile needs at least much (maximum) acceleration as its target.

Locki said...

Rick said:

I agree completely, but the question was whether the missile needs at least much (maximum) acceleration as its target.

=========

Exactly. Thanks Rick.

I'm sure my engagement analysis sounds a bit simplistic which is why I am testing it here

Scenario 1:
Say you are using an expensive NTR missile Bus (accelleration 0.01G) to destroy a cheap Acme N.Korean space station equiped with primitive chemical rockets enabling say 5 seconds of 5G thrust.

If the space station has pre-pivoted and accellerates perpindicularly at 5G in the last 5 seconds of the engagement is this an automatic evasion?

Bear in mind the Missile Bus must pivot too.

Does the Bus or KKV need to be able to generate at least 5G of thrust at some stage in the engagment profile or is it an automatic miss?

To add a level of complexity to the math.



Scenario 2:
Say the Missile Bus does have a 800 second intercept time and is carrying terminal homing KKVs each with chemical rockets enabling 5 seconds of 8G thrust for the terminal phase.

Can it actually still engage if the target sattellite pulses its rockets twice at 2.5 seconds each? Eg one pulse before the terminal KKVs are released (when the Bus is using its low thrust NR) and a second pulse when the KKVs are homing in on the terminal phase.



As an aside. Since in all likelihood you are trying to hit a target that is in a different orbit to you the engagment of the KKV is highly unlikely to be head-on. Its going to be a tricky intercept path. A low thrust but high delta-V missile bus will still merely be on an aggressive intercepting orbit.

Locki said...

Tony said...

WRT targeting, I made this point obliquely in an engagement analysis earlier, but I guess it needs to be made more explicitly. If you're trying to dodge, even at several Gs, don't expect to have much luck with it. If the KKV has to make its final correction at one second to predicted impact, you can only move your ship five meters per G you lay on. If you accelerate at 3 Gs, you move 15 meters. If you accelerate at 5 Gs, you move 25 meters. Also, it only takes 1/10 mil precision to hit within a 5 m circle from 50 km. If you're arriving at only 5 kps relative velocity -- much more likely than 50 kps, in the PMF -- one only needs 1 mil precision to hit within a 5 m circle. As stated earlier, that's the level of precision that modern ground troops regularly achieve in aiming their weapons, using reltively inexpensive optics.

There's no reason why the target ship can't begin its evasive maneuver well before the final few seconds.

If the target missile doesn't have enough thrust to match the target ship to correct its aim before it overflies its target is it an automatic miss?

Say your terminal KKV can generate 10G thrust for 10 seconds.

The target ship can generate 5G 10 seconds.

In the last 3 seconds of the engagement my ship (max accelleation 5G for 5 seconds) is already pre-pivoted ready to accellerate perpindicularly to the incoming KKV. This could make a hit tricky.

In fact the target ship could begin "spinning" in the terminal phase so its thrusting axis remains perpindicular to the incoming missile. That way I can thrust in an unexpected direction.

Anonymous said...

You still have to keep the bus itself from hitting you.

Ferrell

Anonymous said...

An NTR is not going to have 5G's of acceleration - the mass of the reactor is going to get in the way, along with the other mission requirements.

A chemical fighter has only disadvantages compared to the missile chasing it in a straight race, you are comparing a minvan to a sports car (IE assuming it was only about accel).

It has to waste mass for things the missile doesn't care about. So given the same propulsion systems and comparable mass ratios the Missile wins.

The only way the NTR wins is if it has say 1 G accel for 101 seconds where the missile only has 10G for 10 seconds. (again in a straight race scenario)

Meanwhile several of missiles 2-25 being a little bit behind missile one are far enough back to adjust their vector to compensate for this new accel and predicted target vector and they blow up the target.

========

The exception would be if the missiles were designed for blowing up Laser-Stars ... those would not be able to "chase down" fighters - since that would be a waste of mass.

Instead many (90%?) of those missiles might only have enough DeltaV to force the Laser-Star to fire at them, with quantity winning of quality. In that case a dodging Laser-Star is just as good as a shooting one - since it can't blow up missiles effectively when dodging.

(SA Phil)

Anonymous said...

And in a world with super dodging ships a few well placed armed missiles would end this float like a butterfy stuff.

It would be hard to out accelerate the missile plus 1-3 extra kps of variable vector change.

(SA Phil)

Anonymous said...

Also geometry suggests if a targeted ship stars accelerating early at a lateral angle, the missile will actually need less total acceleration to keep up.

Since it does not need to motor to keep the vast majority of its speed.

It can literally cut the fighter off at the pass.

(SA Phil)

Samantha said...

What is all of this talk about the target ship being pre-rotated and ready to thrust whereas the KKV is not? The way I see it there's no reason why the KKV can't rotate itself to match the thrust direction of the target during its terminal phase. Same goes against a spinning target, the KKV could spin in synchronization and adjust its course using its main engine as a popcorn thruster.

TOM said...

Ok, lets say dodging is unlikely, if the missile has enough delta-V and meant to attack "fast small" targets instead of a big slow one, in the later case it might lacks the acc and accuracy.
Dodging a bigger shrapnel is a different issue.


Tony : I asked another thing. You wrote the craft's average acc will be about 0.1G.
With near emptied tank, could it provide enough acc to land on a moon, or a planet with atmosphere?

I thinking in a constellation that can handle various situations beside exact naval battles, cos the last one will be very rare in PMF.

Lets see, lunar or asteroid mining colony rebels, hostile nation starts to smuggle weapons to them.
I dont intend to nuke them.

So i'd like a mothership and parasites /that can have mission oriented payload/ combo to deal with the following possibilities :

- bomb down some PDF batteries, use half the FAC to deploy surface troops, keep other half for patrol duties, maybe support the groud troops with precise attacks from low orbit, when the mothership is on the other side.
- just left half the parasites there for peacekeeping, while i send mothership further to threat to hostile nation
- im attacked by two battlecruisers use my torpedos and FAC to deal with them, then use the remaining parasites for either the patrol or deploy role
- giant PDF battleship on low orbit, it can change its course to hide from my torpedos, the FAC has to charge and reach low orbit, covered by heavy suppress fire, chaff clouds around them and things like that, then attack PDF battleship from low orbit, maybe from multiple directions

Locki said...

Thanks guys.

I was just running some theoretical numbers. I knew a dodge was unlikely.

Still high thrust would be useful so the spacecraft can stay out of the others' KKVs engagement envelopes for a period of time. I think I read somewhere the Aim-9X can pull 100+ G's (vs 7-9G for a fighter) but kinematics and maneuvrability is still important so that the fighter gets the most favourable engagement profile possible for its missile.

A skillful pilot may still be able to turn inside the missile if it is approaching too fast too.

How much extra thrust would injecting O2 into a hydrogen NTR actually produce?

Presumably the flowrate of hydrogen in a NTR is pretty pathetic (compared to the Shuttle's main engines) so the extra thrust from the chemical reaction is probably not great.

Since the NTR engine isn't really optimised for the thrust from a chemical reaction I assume the efficiency of the chemical reaction will be poor too.

I thought one of the problems with an NTR was the corrosion from the hot propellent coming into direct contact with the fission reaction? Or is this problem propellent dependent? Presumably H2O and ammonia are worse for this than monoatomic hydrogen.

Byron said...

Locki:
The thrust from oxygen injection is not from the chemical reactions. Its from the oxygen increasing the mass of the exhaust. If three times as much oxygen as normal hydrogen is added, the exhaust velocity will fall by a factor of 2, and thrust will double. The chemical reaction is relatively minor.

Tony said...

Rick:

"I agree completely, but the question was whether the missile needs at least much (maximum) acceleration as its target."

Once again, I was assuming people could read my mind. (Bad Tony, baaad Tony...) What I was trying to get across is that the KKV doesn't have to match the target burn for burn. It just has to adjust as that tactical situation changes, on an iterative basis.

Tony said...

Locki:

"There's no reason why the target ship can't begin its evasive maneuver well before the final few seconds."

No, but there are other limitations. Stay tuned.

"If the target missile doesn't have enough thrust to match the target ship to correct its aim before it overflies its target is it an automatic miss?"

If it can't match target maneuvers, it will miss, of course. That's a tautology.

"Say your terminal KKV can generate 10G thrust for 10 seconds.

The target ship can generate 5G 10 seconds.

In the last 3 seconds of the engagement my ship (max accelleation 5G for 5 seconds) is already pre-pivoted ready to accellerate perpindicularly to the incoming KKV. This could make a hit tricky.

In fact the target ship could begin "spinning" in the terminal phase so its thrusting axis remains perpindicular to the incoming missile. That way I can thrust in an unexpected direction.


The incoming KKV has 1,000 mps of delta-v. The target has 500 mps. The KKV also has double the acceleration. How is the target going to evade?

Also, the target presumably has a mission beyond surviving the immediate engagement. It can't use all -- or even most -- of it's delta-v dodging rocks people are throwing at it. Even 500 mps is a lot in the pmf.

Finally, there are practical engineering considerations we're not addressing here. A rocket capable of 5 Gs would take several seconds to come up to thrust, and has to maintain a relatively steady throttling profile. Otherwise it will tear itself apart. Small hp gas thrusters or solid popcorn thrusters only take milliseconds to start up and shut down. The KKV should have no problem whatsoever matching target maneuvers.

Tony said...

Locki:

"Still high thrust would be useful so the spacecraft can stay out of the others' KKVs engagement envelopes for a period of time. I think I read somewhere the Aim-9X can pull 100+ G's (vs 7-9G for a fighter) but kinematics and maneuvrability is still important so that the fighter gets the most favourable engagement profile possible for its missile.

A skillful pilot may still be able to turn inside the missile if it is approaching too fast too."


100 Gs? AIM-9X can accelerate at more than 20 Gs. (Inferred from the fact that the warhead fuze has a safety device that requires 5 sec at 20 G to arm.) That would longitudinally compress the airframe. But the airframe is strongest in compression along its long axis. I doubt it could endure turns at similar accelerations. Since the average missile airframe can endure 100 Gs longitudinally, I'd be surprised if the AIM-9X could endure more than 30-40 Gs in a turn.

Also, we have to recognize that the KKV in space is never going to make a turn. It's going to have it's sensors pointed in the direction of the target, and thrust laterally to make aiming correction or to match target maneuvers. The engagement envelope is almost certainly going to be bigger than the target's ability to maneuver. The KKV is designed to burn up all of it's delta-v to get a hit, while the target can only burn up a small fraction of its delta-v to dodge. The KKV is also more maneuverable to begin with, because it's only a few dozen kilograms at most, while the target is hundreds of tons.

Tony said...

TOM:

"Tony : I asked another thing. You wrote the craft's average acc will be about 0.1G."

I actually said that NTRs had accelerations in the thenths of a G. That means something like .3 or so G.

Aside from that, I really don't care what you do with it. I will tell you that I don't believe in battleships, battlecruisers, torpedoes, etc in the pmf, with NTR type propulsion.

Rick said...

I will tell you that I don't believe in battleships, battlecruisers, torpedoes, etc in the pmf, with NTR type propulsion.

Whatever those terms would even mean, in context. That goes to my bias against borrowing familiar terms. They bring baggage and associations with them, that probably don't fit well to either the space environment or the intended vehicle itself.


By the way, have you looked closely at the blog's header image? The ship pointing toward the upper right is a composite vehicle: a deep-space bus carrying a forward rider section configured for aerobraking maneuvers and possibly landings on smaller bodies.

Tony said...

Rick:

"By the way, have you looked closely at the blog's header image? The ship pointing toward the upper right is a composite vehicle: a deep-space bus carrying a forward rider section configured for aerobraking maneuvers and possibly landings on smaller bodies."

Seen it many times. It didn't strike me as anything more than a pmf version of the Apollo stack, sans the first and second stages -- instead of an expendable stage, an atomic rocket, but otherwise a long-term crew hab and an optimized lander.

Anonymous said...

RE: Missile races

If a target takes off ahead of time exactly laterally (the highest angular change in vecor) -- the chasing missile will need only 77% the target's total accel to completely match its course.

That is really going to make this really tough.

It also highlights the advantage of a strong point defense.

(SA Phil)

Anonymous said...

The best dodge I can come up with would be to wait at the last second and then accelerate at an angle towards the missile, hoping it cant adjust fast enough.

It is unlikely the missile will be able to recover from an actual overshoot.

The missile behind it though will have no problem killing you then.

(SA Phil)

Anonymous said...

Hey, how about we take a break from proving that you gotta kill a KKV instead of dodging it? I want to know what everyone thinks a top-of-the-line combat spacecraft would be like and be called?
Me, I think that it woulf have several small pulsed-lasers (or small particle-beams) for point defense, a medium power constant output laser (for heating things at long range), and several missiles and smaller KKV's for various other attack/defense options; I'd call the largest, longest endurance, most capable an "Asteroid Deflector" and the slightly smaller, higher Delta-V, less-heavily-armed variant an "Asteroid Interceptor"; or just Deflector ship and Interceptor.

I know it's a bit scimpy on details, but I'd like to hear your ideas about it.

Ferrell

Locki said...

Probability of dodging a KKV

The missiles kinematic advantage mightn’t be as crushing as most people assume.

I know people hate analogies around here but since I’m not an engineer by training I have nothing else to work with (bear with me!). If you extrapolate from some current day analogues I think people may be underestimating how useful thrust and manoeuverability will be in space combat. Even if you are a space warship the more manoeuvrability and thrust you have the better off you will be.

The closest analogy I can think of is torpedoes vs submarines. Both move through the same medium. Now a Seawolf class SSN has a good chance of avoiding a torpedo. And its lugging around a lot of extra weight compared to the torpedo: 100+ crew, a pressurised crew compartment, a team of Seals with lockout tubes, periscopes, sonar, radar 50 torpedoes, enough supplies for 3 months duration etc etc etc. Its high speed is an advantage and it gives it a reasonable chance of avoiding a torpedo.

According to Tom Clancy the old Soviet Alpha class (45+ knots) was all but unkillable with a torpedo.

Even when you are firing airborne missiles at surface targets the manoeuvrability of the surface warship matters. The missile has a huge advantage in speed and acceleration (they travel through different mediums) but it still helps if you are agile enough to present your bow to give a smaller target.

On a related rocketpunk side its in our interests to make sure neither lasers nor kinetics are auto-kill weaons of Doom. I think it was Rick or maybe Ken Burnside who said making sure manoeuvrability is relevant makes for a more interesting setting.

Because of the time delay from my end I’ll pre-empt the inevitable howls of derision that’ll come my way with the following points:

1. Even a conventional sub (Collins class SSK) using a similar powerplant to the torpedo (eg electric) has a reasonable chance of avoiding the torpedo

2. Maybe we are jumping the gun in assuming a missile will be lugging around the same engine as the warships. It mightn’t be practical for them to use a really expensive & heavy NTR or nuclear electric drive. Analogies again. If I were to write a contemporary military-techno thriller and China’s secret weapon was an awesome long ranged “nuclear powered torpedo” the credibility of the novel would be instantly ZERO. I don’t see why the economics or engineering challenges of putting a nuclear powerplant into a “space torpedo” should be that radically different to a current day ocean-going torpedo.

3. ASAT vs satellite – mostly for Byron

- I read quite a bit about the USN shooting down that satellite. It took about a week of planning, ground based radars and pre-positioning for the Aegis destroyer to engage a “dead” non-manoeuvering target. So it wasn’t an easy thing to achieve. This is a very bad analogy anyway so I won’t push the issue (eg the SM-3 is deep in Earth’s gravity well).

Locki said...

..... or small particle-beams) for point defense ....

Ferrell


=======

I was under the impression weaponsing a particle beam is pure Anime magitech? I thought it was a case of "they just will not work".



Aside, re: submarines & torpedoes analogy

I'm also preempting people abruptly pointing out speed in water is often a hydrodynamics-drag thing rather than a pure mass thing. As I said its an imperfect analogy but it should make people question some of the presumptions we've made.

TOM said...

Locki : Well, they say particle beams scatter quickly, even when neutralized, although i wonder if the orb-lightning can stay together, maybe we could also create stabil plasma projectiles.


Tony : 0.3 g is enough for moon landing, i guess with aerobreak, enough for landing on a planet.
Thanks. :)
I guess i can have now what i wanted.

Eth said...

Particles beams scatter quickly, so they have less range than lasers. But if they can be produced more easily, or be more powerful than lasers, they could be used as short-range point-defence. They could also be an alternative to lasers on bomb-pumped warheads.
To continue with not-so-adequate analogies, it would be your shotgun pellet, compared to your laser bullet or your KKV rocket.

I'm still very sceptical about a stable plasmoid as a projectile. Why trap an explosion in a projectile, instead of sending a projectile who explode?

Anonymous said...

Locki,

The closest analogy I can think of is torpedoes vs submarines. Both move through the same medium. Now a Seawolf class SSN has a good chance of avoiding a torpedo. And its lugging around a lot of extra weight compared to the torpedo: 100+ crew, a pressurised crew compartment, a team of Seals with lockout tubes, periscopes, sonar, radar 50 torpedoes, enough supplies for 3 months duration etc etc etc. Its high speed is an advantage and it gives it a reasonable chance of avoiding a torpedo.

According to Tom Clancy the old Soviet Alpha class (45+ knots) was all but unkillable with a torpedo.

========

You are leaving out the part where there are basically waves pushing the submarine and torpedoes towards each other at 500 mph.

That doesn't happen at sea. Space is not an Ocean.

http://www.projectrho.com/public_html/rocket/misconceptions.php


(SA Phil)

Anonymous said...

That is of course ignoring any innacuraies of either the submarine scenario, nor the fact a nuclear sub has what amounts the space equivilent of a reactionless/spacetime punsher drive.

(SA Phil)

Anonymous said...

Particle beams are defintely possible - they are made every day.

The device would probably be a lot more elec. efficient than a laser - but much less range. Atomic Rockets has a section on them.

A suitably energetic plasma exhaust stream from say a torch drive might work as a "close range" Point defense - but that would be more operatic than PMF.

(SA Phil)

Byron said...

Phil:
If a target takes off ahead of time exactly laterally (the highest angular change in vecor) -- the chasing missile will need only 77% the target's total accel to completely match its course.
Where did this come from?

Locki:
The torpedo in question affects it a lot. The Alpha was nearly immune to conventional torpedoes, which could only make 40 to 45 knots. However, torpedoes like the ADCAP were developed to deal with it. And the performance advantage of an NTR over chemfuel is minor enough that there is no reason to use on on a missile.

- I read quite a bit about the USN shooting down that satellite. It took about a week of planning, ground based radars and pre-positioning for the Aegis destroyer to engage a “dead” non-manoeuvering target. So it wasn’t an easy thing to achieve. This is a very bad analogy anyway so I won’t push the issue (eg the SM-3 is deep in Earth’s gravity well).
On the other hand, we're not dealing with doing it today. As an example, look at air-to-air missiles. The success rate of the AMRAAM has caused you to classify air-to-air as easy. If, however, we look at the Sparrow, we would classify it as hard. At the moment, we're still in the first-gen (Sparrow) stage. Also, the SM-3 was not designed for ASAT use. A dedicated system would probably be much easier to use.

Tony said...

SA Phil:

"Particle beams are defintely possible - they are made every day."

Yep.

"The device would probably be a lot more elec. efficient than a laser - but much less range. Atomic Rockets has a section on them."

Probably more efficient, but also more demanding. According to The Wiki, the reason particles haven't been weaponized is that you can't generate enough power for them, even on a ship. (Well, a ship can generate enoguh power for a particle beam weapon, but only if you didn't bother about minor things like propulsion.)

"A suitably energetic plasma exhaust stream from say a torch drive might work as a 'close range' Point defense - but that would be more operatic than PMF."

"[C]lose range" being a relative term. I don't think you'd want to get within 1,000 km of a torch drive's boresight axis.

Thucydides said...

If you are looking for the naval analogy of PMF space combat you might be closer off looking at a cruise missile flying towards a ship, or a SKVALL supercavitating torpedo roaring towards the target at 300mph underwater.

The Skvall is probably a good analogy, since its ability to make course corrections is essentially zero; the Soviet skipper who wanted to use them would probably have to fire a spread to ensure one hits (or get one with a nuclear warhead).

Like all analogies, YMMV.

Tony said...

Thucydides:

"If you are looking for the naval analogy of PMF space combat you might be closer off looking at a cruise missile flying towards a ship, or a SKVALL supercavitating torpedo roaring towards the target at 300mph underwater."

No analogy is good, simply because the physics of bodies moving through a fluid and that of bodies moving through a vacuum are just too different. Part of the proble with Skval maneuverability derives directly from the fact that it is underwater -- at the peeds it is travelling the water presnets too much resistance to more than very gradual changes of direction. That is simply not a factor in space.

jollyreaper said...

Supercavitating torps:

VA-111 Shkval - Original variant; GOLIS autonomous inertial guidance.

"Shkval 2" - Current variant; believed to have additional guidance systems, possibly via the use of vectored thrust, and with much longer range.

Inertial guidance means that it's likely not updating target location during the run. While not unguided, I guess you might call it semi-guided?

Thucydides said...

The Skvall cannot make major changes in direction due to the fluid media it inhabits, while a SCoD does not make big course corrections because it only carries a limited amount of propellant. SCoDs would be dispersed in a shotgun pattern by the bus, and make whatever corrections they could to intersect the target (which would be relatively minor on the big scale of things).

So the analogy is really high closing rate and limited ability to manoeuver; ships or subs can make an attempt to get out of the way, but will have only a limited ability on the time scale being considered here.

Tony said...

jollyreaper:

"Inertial guidance means that it's likely not updating target location during the run. While not unguided, I guess you might call it semi-guided?"

It's guided in the same way a ballistic missile is guided -- it flies a programmed course very precisely.

Thucydides:

"The Skvall cannot make major changes in direction due to the fluid media it inhabits, while a SCoD does not make big course corrections because it only carries a limited amount of propellant. SCoDs would be dispersed in a shotgun pattern by the bus, and make whatever corrections they could to intersect the target (which would be relatively minor on the big scale of things).

So the analogy is really high closing rate and limited ability to manoeuver; ships or subs can make an attempt to get out of the way, but will have only a limited ability on the time scale being considered here."


Okay, but it's still a shaky analogy, because the SCoD is not a short ranged weapon, and also it is a sub-munition.

Rick said...

The last ditch engagement against incoming SCODs has a lot of 'granular' factors, due to the time scale.

At longer approach range, thus longer projected time to impact (or not), the situation is a bit more fluid. Even milligee drives can produce a significant evasive sidestep.

Certainly it would be desirable to engage and disable the missile bus before it releases its cloud of SCODs. One question is the flight duration of SCODs. Not just delta v, but mundane things like battery life. It makes a big difference how close in the bus must get before releasing its submunis.


I am no fan of particle beams, which seem like a sort of vaporware weapon. Given how much use has been made of cathode ray tubes, if weaponizing the idea had much promise I think it would have been developed and tested to some degree.

Anonymous said...

Byron said...

Where did this come from?
==========

Someone who uses trig more frequently/recently than I could probably calculate the triangle precisely but I cheated and used a triangle calculator

If you enter in 100 for the side of the ship accelerating Laterally and use a 45-45-90 triangle the side the missile would be racing down has a length of 77.

That would be true of any directly lateral course.

Any couse where the missile made an effort run away/reduce closing velocity - should require even less accel from the missile since it could just coast and allow closing velocity to get it where it wants to go.

Any course where the target moves towards the target has the disadvantage of requiring more accel to get the same lateral acceleration so seems like it would be counterproductive unless there is an overshoot.

The scenario is a bit hard to sketch in this medium - but basically I am envisioning a missile flying at a ship's broadside as it accelerates at max speed.

(SA Phil)

Anonymous said...

Any course where the target moves towards the target has the disadvantage of requiring more accel to get the same lateral acceleration so seems like it would be counterproductive unless there is an overshoot.

==========================

Should read "target moves towards the missile"

(SA Phil)

Locki said...

And for a quick break from the trigonometry ....


Rick said...

Whatever those terms would even mean, in context. That goes to my bias against borrowing familiar terms. They bring baggage and associations with them, that probably don't fit well to either the space environment or the intended vehicle itself.

===========

I actually like the old terms. Especially in fiction where they conjure up the might and grandeur of yesteryear. They are terms which probably lend a more human element to what will in all likelihood be a remote controlled, impersonal computer game of death. They give you a direct link to the past and help the esprit de coprs of the military unit you are writing about.

I also note we have no problem reusing old terms in todays military. There's the 1st Armoed Cavalry devision (No horses in sight!). Military personal of all descriptions are still referred to as "warriors." Hell even the aviation elements of the army are referred to as airmobile cavalry. Realistically todays frigates/cruisers/destroyers have nothing like the same role these classes of yesteryear had but we still reuse the names.

A professional military is unique in that a bunch of privelaged, well fed people from a safe society are willing to give up their lives for a sometimes nebulous mission. The key factor in them maintaining effectiveness is this esprit de corps and I expect the baggage of yesteryear will be carried across to reinforce this.

Locki said...

Particle beams are defintely possible - they are made every day.

(SA Phil)


I'll get back to dodging tonight ..

I thought particle beams were impossible as a weapon for two reasons.

a. If you are firing charged particles it ceases to be a beam very quickly after leaving your accellerators because of mutual repulsion of the charged particles

b. If you are using neutral particle (say neutrons) then you are going to have a hell of a time accellerating them in a synchotron or whatever in the first place.

Which brings me to a 2nd fun diversion from the maths crunching.

We should allvote on the most useless SF weapon you have ever read about.

I will go first.

- A neutrino cannon (hahahahhaha)

Anonymous said...

Locki said:"I thought particle beams were impossible as a weapon for two reasons.

a. If you are firing charged particles it ceases to be a beam very quickly after leaving your accellerators because of mutual repulsion of the charged particles

b. If you are using neutral particle (say neutrons) then you are going to have a hell of a time accellerating them in a synchotron or whatever in the first place."

The range of particle beams in vacuum is determined by rate of dispersion vs velocity. Their range may only be tens of kilometers, but despite this they can be as powerful as lasers. By the way, you forgot 'neutralized' partical beams.

Ferrell

Anonymous said...

Neutrino cannon? How about a telepathic amplifier that tears holes in human minds like a laser tears holes in the fabric of space.

Ferrell

Locki said...

By the way, you forgot 'neutralized' partical beams.

Ferrell


Is this seriously what I think it is? You accellerate charged particles to some fraction of the speed of light. Then as the particles leave your "muzzle" you somehow de-charge or neutralize the particles?

I think I'd rather harnesss the awesome power of midicholorians to fight the evil galactic empire.

Hey wait. Can I also nominate "midichlorians".

jollyreaper said...

No. The perfect scifi weapon is a japanese pop star whose singing can be turned into a powerful weapon against alien invaders.

Anonymous said...

Locki said:"Is this seriously what I think it is? You accellerate charged particles to some fraction of the speed of light. Then as the particles leave your "muzzle" you somehow de-charge or neutralize the particles?"

Umm, no... You develop two charged particle beams (say a proton beam and an electron beam) and combine them just before leaving the weapon. The atoms now have a neutral overall 'charge' and are 'only' subject to thermal scattering. No particle beam that can be reasonally be found in the PMF will have anything like the range of a laser.

Jollyreaper:
Or yoddling...

Ferrell

Anonymous said...

Ferrell: That's actually an idea I haven't heard before. One thing that concerns me is that when you're combining the two oppositely charged particle beams they'll be attracting each other. My concern is that that will create a lot of turbulence at the muzzle which could be a serious problem...

Anonymous said...

Ferrell: I'd be worried that such a setup would induce a lot of turbulence at the muzzle as the two streams attracted each other.

~~
Samantha

Locki said...

jollyreaper said...

Umm, no... You develop two charged particle beams (say a proton beam and an electron beam) and combine them just before leaving the weapon. The atoms now have a neutral overall 'charge' and are 'only' subject to thermal scattering.


========

Hang on. Wait a sec. I'll be the first to admit my subatomic physics is grade school level but just because I bang an electron into a proton doesn't mean I suddenly have a neutral particle flying out a muzzle as a beam of death. Besides you'd need two huge ass synchotrons for each particle beam. Magitech!

Surely, you are better off the sheer awesomeness of the Minmay Attack (TM)!

"Attention real men of the blinding corvette flotilla. Lower your shutters and prepare for the attack run on the drone Laserstar USSN Byron. We have no cover fire from our own laserstars, all of our IR sensors are blinded and there's only enough delta-V for a one way trip. We will rely on Minmei's song to confuse the soul-less, remote controlled enemy. Begin broadcasting on all channels."

To be in love
Must be the sweetest feeling that a girl can feel
To be in love...
To live a dream
With somebody you care about like no one else.


[Meanwhile back on the USSN Byron]:
Admiral Rick: "Auurrggghhh! The power of Japanese Pop Song is too much for our magitech targetting systems, the power of hope has killed the unobtanium heat resistent, atomic accuracy, precision actuators ........ nooooooooo"

TOM said...

Well, particle beams are surely very inefficient in air, they scatter very quickly. In space they can stay together longer.

Eth : in SF orb-lightnings or plasma beams are between lasers and solid projectiles : they punch more then lasers, but also more demanding, and they dont deplete as fast as missiles.

Otherwise i wondered about theese ones :
http://www.globalsecurity.org/military/systems/aircraft/systems/ircm.htm
http://www.globalsecurity.org/military/systems/aircraft/systems/tadircm.htm

If such things can be already equipped to plane, maybe missile blinding short-range lasers arent a bad idea on small targets.

TOM said...

Otherwise what Locki said about computerized game of death : i wonder if in the future anime like mechas will fight each other on ground, while drone ships in space... but there are still things that cant be robotized, espionage for example as you mentioned, and II WW gives many examples, how it can affect the outcome of war.

Eth said...

- A neutrino cannon (hahahahhaha)

Ok, where did you ever heard about a weaponized neutrino cannon?
Call me naive, but I won't believe that anyone can be that dumb without sources.

[Meanwhile back on the USSN Byron]:
Admiral Rick: "Auurrggghhh! The power of Japanese Pop Song is too much for our magitech targetting systems, the power of hope has killed the unobtanium heat resistent, atomic accuracy, precision actuators ........ nooooooooo"


Are you kidding? It's even more dangerous than that.

[Space Command]
"Admiral Rick, is the resistance neutralized? Admiral Rick, report! Admiral, you are on attack vector on our base!
Geez, not *again*...
Attention, all units! The third fleet is compromised and to be considered hostile! I repeat, the third fleet is ... wait, what's this music?

Japanese pop stars are the weaponized version of the 'Humanity is infectious' trope...

I heard from a Warhammer 40 000 fan that in their last reboot, they added a Necron superweapon : a replica of the entire galaxy, with every star. If one of the stars is extinguished in the map, the real star will die several millennia earlier.
Not "in several millennia", but "several millennia earlier".
Most useless superweapon ever.
(We are still wondering if it was a translation mistake, but given the record of Games Workshop to utterly ignore any kind of scale...)

Eth said...

Locki:
Hang on. Wait a sec. I'll be the first to admit my subatomic physics is grade school level but just because I bang an electron into a proton doesn't mean I suddenly have a neutral particle flying out a muzzle as a beam of death.

Uh, unless I'm wrong, yes, you have. Protons and electrons attract each-other, as much as protons and electrons repel themselves, resulting in a neutral beam.
For what I read, you mayn also directly be able to create a plasma beam (which would be pretty much what this neutralized beam would be) with a bomb-pumped warhead. Not unlike ORION pellets, but more "shaped like a beam" to try to cause damage.

Besides you'd need two huge ass synchotrons for each particle beam. Magitech!

More than giant lasers or swarms of ultra-precise manoeuvring KKV?

Locki said...

Eth said...

Ok, where did you ever heard about a weaponized neutrino cannon?
Call me naive, but I won't believe that anyone can be that dumb without sources.


=========

Your Google-Fu is weak young Padawan.

Disclaimer: Readers of this blog under 15yo please make sure you are accompanied by a parent before reading further. The following examples of SF weaponary can be disturbing and contains violent imagery.

1. http://tvtropes.org/pmwiki/pmwiki.php/Main/PhotoprotoneutronTorpedo
- Artemis Fowl: Neutrino Charges and neutrino handguns
- Cyber Empires: Neutrino Cannons are the "ultimate weapon"

2. http://stars.arglos.net/articles/ssg/ssgcfrm.htm
- Stars! (computer game): Lo and behold the mighty gatling neutrino cannon so that you can be really pummelled by rapid firing massless,chargeless ghost particles.

Anonymous said...

Hmm odd.

A particle beam surely doesnt need to be giagantic or mass intensive - before flat screens everyone in the free world had one in their living room.

However a particle beam weapon that is mass frugal would need to be really long, and it would take a lot of power ... essentially the same downsides as a coilgun.

Neutral beams are beams where the charge is removed - the basic process is listed in wikipedia and in atomic rockets (though that site seems to be down for me atm)

=======================
=======================
((from wikipedia))
Stages:

1.While the charge on the electrode is positive, the ions are attracted to the negative charge on the electrode, and thus bunched around it.
2.The alternating voltage switches the charge to negative on the accelerating electrode.
3.The negative charge electrostatically repels the negative ions and accelerates them to near the velocity of light.
4.The resulting high energy beam of anions passes through a chamber filled with low pressure gas.
5.There, collisions with the gas strip the extra electrons from the anions, and thus make the particle beam neutral.
6.The particle beam proceeds straight to its target, and damages it by running into it, and by disrupting the structure of the target with its kinetic energy.
=============================
=============================


Ranges listed in Atomic rockets sounded more like thousands of kms with tens of thousands for the neutral version. Which is "short ranged" only in a relative sense.

Many of the disadavtages related to particle peam weapons are worse on an inhabited planet (From the Radiation) As metnioned a particle beam handgun would have the problem of dosing the shooter.

Tony mentioned the power requirements being high for an effective weapons - that is very true. It is the same problem the laser has of course. Particle beams only last nano-secongs though so you would use a capacitor bank and so forth.

The big advantage I see with a particle beam is it shares many basic functional ideas with several types of electrical drive systems, so in my mind it might be possible to do both with the same device.

(SA Phil)

Byron said...

Phil:
(Bunch of trig)
I'm sorry, but this is all wrong. The best way to look at it is to break it down to two dimensions, lateral and line-of-flight. The projectile is moving directly towards the target, so initially there is no lateral velocity. If the target begins to burn laterally, the projectile will have to match it step for step (plus a little bit, to compensate for lag). There's no way to cut the corner.

The big advantage I see with a particle beam is it shares many basic functional ideas with several types of electrical drive systems, so in my mind it might be possible to do both with the same device.
Highly unlikely. The drive has to work in a steady-state for long periods, and a little bit of dispersion (a few degrees) isn't a problem. Having the same device discharge a much more tightly focused pulsed power beam is unlikely. In much the same way, the Kinzi lesson is useless in practice because of how fast the exhaust disperses and how hard it is to do.

Locki:
Neutrino is the name of a brad of laser-ish handguns in Artemis Fowl. Either it's said that they're lasers, or it's left unclear.

Anonymous said...

Byron,

I'm sorry, but this is all wrong. The best way to look at it is to break it down to two dimensions, lateral and line-of-flight. The projectile is moving directly towards the target, so initially there is no lateral velocity. If the target begins to burn laterally, the projectile will have to match it step for step (plus a little bit, to compensate for lag). There's no way to cut the corner.

=====

Nope, in the scenario we were discusing Locki was cutting and running (laterally) early.

It literally was just an open field tackle.

(SA Phil)

Anonymous said...

Byron,

Highly unlikely. The drive has to work in a steady-state for long periods, and a little bit of dispersion (a few degrees) isn't a problem.

========

Why can't the drive pulse instead?

Sir Newton doesn't care.

(SA Phil)

Byron said...

Phil:
Nope, in the scenario we were discusing Locki was cutting and running (laterally) early.

It literally was just an open field tackle.

No, you were wrong. There is a distance advantage, but translating that into a velocity advantage is not correct. Under CBDR guidance, the projectile has to spend as much delta-V as the target does to keep it centered. Otherwise, the target retains lateral velocity, and the projectile misses. Again, we are not dealing with football and displacement, but with spacecraft and velocity.

Why can't the drive pulse instead?

Sir Newton doesn't care.

No, but your engineer does. I've read fairly extensively on the subject, and nothing I've seen has even mentioned pulsing. That indicates that it will probably drive up cost and mass considerably for no gain. Also, I'm not sure that a conventional electric thruster can even put out a beam that would be useful. The velocities involved are orders of magnitude apart.

Byron said...

On a completely unrelated note, this thread now holds the post record.

Anonymous said...

Byron,

No, you were wrong. There is a distance advantage, but translating that into a velocity advantage is not correct.

======

If closing velcoity relative was zero, both start accelerating one laterally one diagnally with a distance advantage.

Given equal accels, the one with the shorter distance to travel wins.

make the closing velocity some high number - are you saying that now the former winner loses? I think it actually becomes easier.

This isnt a chase, the missile knows where the target is going it just aims there.

(SA Phil)

Anonymous said...

Byron,

No, but your engineer does. I've read fairly extensively on the subject, and nothing I've seen has even mentioned pulsing. That indicates that it will probably drive up cost and mass considerably for no gain. Also, I'm not sure that a conventional electric thruster can even put out a beam that would be useful. The velocities involved are orders of magnitude apart.
================

The advantage is the in the dual function nature.

It also would allow you to have higher power for the drive at the cost of sustained output.

You wouldn't have read it because no current design criteria would have used the idea. Trying to design a dual weapon/electric propulsion system isn't very high on anyone's current real world priority list.

Also the particle weapon does not need to be near C. It just is most often discussed that way.

(SA Phil)

Byron said...

Phil:
Moving diagonally is shorter then moving along both sides of the triangle.
Example:
You and I are standing in a field 10 yards apart. I run perpendicular to the line between us, while you try to catch me. The most efficient way is to match my lateral velocity, and use what's left to close the gap. But if you're slower then me, you can't catch me.

My point on the drives is that the requirements are incompatible. A particle beam needs velocities in the thousands of km/s. The drive is maybe 100. I'm not sure if normal electric thrusters even can go that high. Also, the exhaust disperses. There is virtually no commonality between the two, so merging them is probably not a good plan.

Locki said...

Back to the more mundane topics of dodging incoming KKVs.

I'm pretty sure Byron has the correct analysis. Its just easier to pretend its all in a 2D plane and break it down into a perpindicular vector and the closing vector. Its a bit like leading your sniper shot mid-flight. The closing KKV needs to be able to "sidestep" as quickly as the target warship. This will be complicated by the KKV presumably needing to keep its nose (seeker) pointed at the target as long as possible and consequently thrusting along the long axis. The warship knows the vector the KKV is coming in on and begin accellerating perpindicular.

Eg for most of the flight the warship can sidestep laterally using its big beefy main engine whereas the KKV will be trying to match its lateral accelleration with its popcorn manouvering thrusters or the lateral vector component of its main engine.

The defender obviously has several huge advantages here. It can afford to use a high thrust, low ISP chemical engine and just stay in orbit waiting for the attacker to come to it.

If the attacker begins attacking at extreme range with lasers or KKVs the defender can just change orbit and keep the planet between it and the attacker.

If a swarm of KKVs are coming in the defender may even do something clever like abruptly change its vector by bouncing off the atmosphere with an aerobreak. It'll play havoc with the sensors of the KKV and they mightn't be able to match the sudden change in vector anyway

Locki said...

Re Byron: earlier post on defocusing the laser to get accurate targetting information

===========

The wheels turn slowly in my head sometimes.

I don't think this works to help correct your aim either.

Say you defocus your laser to generate a huge 3km spot size at 150,000.

Lets say your alignment is just a touch out and only the very lower quadrant of the laser spot at 5 o'clock hits the target.

This doesn't actually tell you which way to re-aim the laser. Even though a section of my huge laser spot is hitting the target I have no way of knowing if its high, low, left or right.

Assuming real world conditions where alignments always change (flex of superstructure, heat etc) the laser could be horribly inaccurate because of its inability to "correct its aim." Which is in mark contrast to kinectic cannons or KKVs

Anonymous said...

The ABL uses different lasers for targeting and attack. An IR sensor would show you where you hit, but not where you missed. Maybe moving the laser in a pre-planned pattern durning attacks would help.

Ferrell

Thucydides said...

The laser simply has to be focused to a spot equal to the size of the ship to inflict thermal stress/damage (your radiators will become uncomfortably hot) if you think killing shots will be too difficult. Rastering the beam will also give you the ability to put lots of energy on target (and making it harder for countermeasures/damage control).

The shotgun pattern of incoming KKV's (SCoD's or larger size) will force the skipper/control algorithm to make a choice: stand and fight or evade. If the ship is evading, it will be somewhat to totally out of the fight (depending on the capabilities of the ship and systems). Dodging enough incoming clouds could force you totally out of position or use up all your fuel/remass. Even atmospheric dodges like aerobraking will put you well out of position (especially once you are below the planetary horizon WRT the enemy fleet). They can simply track your path, do some calculations and shoot another cloud to meet you as you come over the other limb of the planet as you finish your orbit.

Finally, a treat. Atomic Rockets is a subset of a much larger site, here is some artwork of a semi PMF ship using NTR type propulsion and carrying a brace of missiles. The rest of the site has similarly great artwork: http://www.projectrho.com/warpwar/warpwarCGI06.html

Thucydides said...

And for the totally compulsive, here is the link to the "Orbiter" website; you can download software and simulate spaceflight (and presumably space battles) to your heart's content:

http://orbit.medphys.ucl.ac.uk/index.html

Locki said...

Thucydides said...

The laser simply has to be focused to a spot equal to the size of the ship to inflict thermal stress/damage (your radiators will become uncomfortably hot)

==========

At best the laser has 20% efficiency. With such a low efficiency isn't using a laser to overload someone else's radiators a bit self defeating?

eg you will cook yourself 4 times as fast as the target

Being out of position is a lot better than being dead. Dodging is still viable. You mightn't be that badly out of position anyway. And besides the attacking ship doesn't have an unlimited supply of KKVs - those shots which miss are eating into your mass budget too.

Anonymous said...

Here's an idea on how to dodge KKVs: What if you had pairs of ships which were connected by some kind of tether. The two ships would then begin to rotate around each other. As KKVs closed in the two ships could either extend or retract the cable to very rapidly increase or decrease their rotational velocity, kinda like a ballet dancer.

I imagine it might make hitting the ships very difficult. Same goes for the cable, even though you don't really care that much about the cable anyway because it's not really that critical to the ships' operations.

~~ Samantha

TOM said...

About KKV defence : yes i also had this ideas : descend into atmosphere, although it also impairs the ability of active defence.
Orbital mechanics, if attacker is on high orbit while defender is on low, it can change the course to hide, multiple waves can counter it, but it decrease efficiency anyway.
And you cant just carry torpedo swarms.
If you atacked by a missile bus, you might blind the main bus with beam weapons, blind heat seekers, attack electronics with ionizing beams, then you only have to deal with the smaller warheads.
Fire SHIELD like projectiles to break up the things, then Whipple shield with multiple active armor layers can save you from remaining shrapnels.
If the target is on low orbit, its a possibility to arrange your fighters to attack from multiple directions, then it will be MUCH harder to defend yourself.

Laser protection : i already said jamming, suppress fire to attack the mirrors, while charging ships shutter their lasers (if they have such things) and rotate around axis. Chaff clouds around you, possibly illuminated by lasers to blur your conturs.

Of course no attack or defence is perfect.

I guess, for destroying a single fleet, the battleship will be the best, but theese naval battles will be very rare, mostly you will have shore missions, peacekeeping, anti guerilla, terrorist, etc operations, that calls for mothership and parasites, frigates.

One of my keyword is versatility : it is bad to say, sorry guys political situation has changed, we dont have to ruin that rebel colony, go back to base ASAP for assault boats. Or find out, that you dont really need occupy forces, just leave some patrol boats there to prevent new fightings between mining colony A and B.
Or replace your frigate for torpedos and small craft because if you have to descend, charge, it is better to have multiple small targets /that can be more easily replaced/ then one big.

Of course specialized units and equipments are better for a given situation, but i imagine a game, where you have to remain versatile, when you launch, you dont know exactly what will you have to deal with.
Although superior intelligence can boost your efficiency.

Anonymous said...

Byron,

My point on the drives is that the requirements are incompatible. A particle beam needs velocities in the thousands of km/s. The drive is maybe 100. I'm not sure if normal electric thrusters even can go that high. Also, the exhaust disperses. There is virtually no commonality between the two, so merging them is probably not a good plan.

===============

My point is that all these electric thrusters are essentially steady state particle accelerators.

And all conventional particle accelerators are essentially pulsed electric thrusters.

They are all basically devices that accelerate particles using electrical forces / magnetic fields.

Therefore- it should be possible to design a bimodal system that can do the following:

Mode One - accelerate a larger quantity of particles to a slower velocity.

Mode Two accelerate a smaller quantity of particles to a higher velocity.

The fact that such a system doesn't exist now isn't any more relevant than your 100 MJ laser not existing now.

The question is, is it possible to have a particle source and a linear electrical /magnetic acceleration system of certain capabilities. At this level of basic concept, I would suggest it is.

(SA Phil)

Anonymous said...

Byron,

Moving diagonally is shorter then moving along both sides of the triangle.
=========

Having worked this out in several ways on paper and I realized my mistake.

And it turns out Locki and Byron were right. It will be possible to evade a KKV, and even a KKV cloud if you have a higher acceleration capabilities than the KKVs -- even with high closing velocities.

The higher accelerating evading ship always ends up beyond the interception point. So without adding some kind of weapon to compensate for this to the KKV a high accel target is going to have some distinct advantage in defense.

In fact I think the 77% I came up with was the inverse of the truth. At zero relative closing velocity the evading ship needs only >77% of the acceleration of the missile to escape. This ratio goes up with closing velocity.

(SA Phil)

Anonymous said...

By acceleration in the above comment I mean total Acceleration.

Both max acceleration rate and the amount of time it can accelerate during the encounter.

Thus torch ships are going to be really hard to defeat with KKV clouds (that don't have some kind of torch capability themselves)

(SA Phil)

Anonymous said...

hmm to clarify that would be at a specific range - Where the distance between missile and target was equal to acceleration capability of the missile (constant acceleration till impact) ... at that point if the target takes off laterally with more than 77% of the same accel capacity it will escape.

(SA Phil)

Byron said...

Phil:
My point is that all these electric thrusters are essentially steady state particle accelerators.

And all conventional particle accelerators are essentially pulsed electric thrusters.

They are all basically devices that accelerate particles using electrical forces / magnetic fields.

Therefore- it should be possible to design a bimodal system that can do the following:

Mode One - accelerate a larger quantity of particles to a slower velocity.

Mode Two accelerate a smaller quantity of particles to a higher velocity.

I know exactly what you mean. I just don't think it's possible. They do the same thing only superficially. An ion thruster tops out somewhere around 200 km/s, and is designed to efficiently push particles in the same general direction (a couple of degree cone). A particle beam has to push the particles fast (a significant percentage of c) and in a very tight beam. Claiming that merging the two is possible is like suggesting that designing a combination rifle/grenade launcher (and, yes, I know about rifle grenades, which are not feasible in the case of thrusters) is likely to be significantly lighter then the two separately. After all, one pushes a little projectile quickly, and the other pushes a big one fast, right?
In fact, the only savings are in the external furniture for use on the shoulder, not the weapons themselves.
Also, most particle accelerators (except for electrostatic accelerators) work on completely different principles from ion thrusters. I don't think you could get a weapons-grade beam out of one of those, so it seems like a bad idea.

Locki:
At best the laser has 20% efficiency. With such a low efficiency isn't using a laser to overload someone else's radiators a bit self defeating?
Why do we assume such a low laser efficiency? My spreadsheet uses 60%, which I think I got from Luke.

TOM said...

Well, know i have the idea, what if a cyclotron would be at middle, it could release a beam backward and simply let it scatter, or fire forward and keep it together?
The motor of the systems might be the same.

Tony said...

Locki:

"At best the laser has 20% efficiency. With such a low efficiency isn't using a laser to overload someone else's radiators a bit self defeating?

eg you will cook yourself 4 times as fast as the target"
'

Nope. Let's say you're both shooting at each other. You're hitting him and he's not hitting you. You can manage all the heat you can generate. But he's got to manage all the heat he can generate, plus the heat you're pumping into him. The result is either that he has to shoot less, or dodge. In any case, you degrade his capabilities.

"Being out of position is a lot better than being dead. Dodging is still viable. You mightn't be that badly out of position anyway. And besides the attacking ship doesn't have an unlimited supply of KKVs - those shots which miss are eating into your mass budget too."

One doesn't shoot KKVs in series. One shoots them all to overload the enemy's ability to defend/dodge. Same logis as WW2 carier combat.

Tony said...

SA Phil:

"And it turns out Locki and Byron were right. It will be possible to evade a KKV, and even a KKV cloud if you have a higher acceleration capabilities than the KKVs..."

Which is not at all likely. Also, a ship with higher overall delta-v can't dodge based on the delta-v. Unlike the KKV, it can't afford all of its delta-v to successfully conclude a single engagement. Think of it like a WW2 battleship vs attacking aircraft. Yeah, the battleship can steam 12,000 nm on one load of fuel, while the planes can only go 1,000 nm or so. But that doesn't matter, because the planes can move faster. Same thing in space, a ship might be able to change it's velocity by dozens of kps, but only at a few m illigee of acceleration, while the KKV can change it's velocity only a few hundred mps, but at tens of mps per second.

Therefore- it should be possible to design a bimodal system that can do the following:

"Mode One - accelerate a larger quantity of particles to a slower velocity.

Mode Two accelerate a smaller quantity of particles to a higher velocity."


Not likely. It's a question of optimization. You can't have a machine good at both jobs.

Anonymous said...

Byron,

Claiming that merging the two is possible is like suggesting that designing a combination rifle/grenade launcher

-----
Not really, its more like combining a rifle and a low velocity rapid fire shotgun.

I am suggesting rifling the barrel, adding a selectable choke and using two different ammunition feeds.

I don't mean to suggest it would resemble either a modern thruster nor particle accelerator design.

For the simple reason that neither are designed to do what I suggest - and if a project were put in place to develop the concept they would be using a purpose built design.

These are charged particles - there are a lot of ways to manipulate them - that is why there are so many different electric thrusters and particle accelerator designs.

(SA Phil)

Anonymous said...

Tony,

Not likely. It's a question of optimization. You can't have a machine good at both jobs.

------
Sure you can. You are just speaking in generalities.

I can make a Truck that gets good gas mileage and is good at towing.

I can also use that Truck to generate Electrical power.

I could even make it amphibious if I wanted, be seaworthy and get decent speed for a displacement hull.
=============

Now is it excellent at both jobs? As good as specially designed systems? Probably not - but that isn't what I am suggesting.

I am suggesting it can do both jobs requiring less mass than two separate specialized systems.

Those specialized systems which would have to be smaller to have both as separate optimized systems - would actually be less capable than the hybrid system.

(SA Phil)

Anonymous said...

Going back to the rifle and shotgun comparison. A purpose built rifle and a purpose built shotgun would be better than the hybrid - but they would weigh more.

Since any soldier in this comparison can only carry so much weight - he cant carry both a high powered rifle and a rapid fire shotgun - he gets to choose between the hybrid weapon or a less capable small carbine plus a slow firing small shotgun.

Depending on the technology and design of the hybrid it could likely be better than either of the small choices at their jobs.

(SA Phil)

Anonymous said...

Tony,


Which is not at all likely. Also, a ship with higher overall delta-v can't dodge based on the delta-v. Unlike the KKV, it can't afford all of its delta-v to successfully conclude a single engagement. Think of it like a WW2 battleship vs attacking aircraft. Yeah, the battleship can steam 12,000 nm on one load of fuel, while the planes can only go 1,000 nm or so. But that doesn't matter, because the planes can move faster. Same thing in space, a ship might be able to change it's velocity by dozens of kps, but only at a few m illigee of acceleration, while the KKV can change it's velocity only a few hundred mps, but at tens of mps per second.

===========

You are actually talking about something different.

I was figuring out if it were possible for the ship to evade. You are saying it is a bad idea for it (even if capable) to evade due to mission constraints.

It is possible. Given certain performance parameters.

It may be a bad idea. Given certain performance parameters.

The less operatic the drive the most likely the ship cant do either. But with a demi-torch you might be able to do both - it really depends on all the scenario's assumptions.

You have often suggested fusion drives. Those could be demi-torches in many scenarios.

(SA Phil)

Anonymous said...

As an example of a possible hybrid perhaps you could have the following - (I am not saying this one will work, it is an idea) -

You have a really long tube designed to accelerate negatively charged particles. It is fed by large capacitor banks. It can either accelerate at high power mode where it will accelerate electrons to some useful fraction of C.

Or it can fire more often but the acceleration suffers. Some of its capacitor/cooling capability goes unused in this mode. (weapon and thrust power are not the same)

When used as a Weapon it accelerates electrons which are initially introduced by an electron gun at one end of the tube.

When it is used as a Thruster the electron gun is instead used to ionize a gas, the resulting plasma is accelerated instead.

(SA Phil)

Locki said...

Tony said...

One doesn't shoot KKVs in series. One shoots them all to overload the enemy's ability to defend/dodge. Same logic as WW2 carier combat.

================

It seems to me in military history there have always been two approaches to destroying the target.

1. You can use a very small number of precision, high value weapons guaranteed of a hit /kill eg Air to Air Missiles, Torpedoes, Katana

2. Overwhelm the defences with a swarm of cheaper weapons designed to saturate the target eg VLS Aegis Cruiseres, artillary barrage, Longbow arrow storm.

You can choose whichever method you like for your SF setting but both are equally valid. Furthermore considering the mass constraints of a Space Warship I'd suggest the first method is more plausible. It has similar-ish mass issue to warplanes and submarines. Whereas, historically a swarm of missiles is usually used from platforms where mass is not a critical issue (eg surface cruiser. I've never liked the swarm of KKVs scie-fi trope for this reason but I guess an author can choose whichever strategy he likes.


Which is not at all likely. Also, a ship with higher overall delta-v can't dodge based on the delta-v. Unlike the KKV, it can't afford all of its delta-v to successfully conclude a single engagement. Think of it like a WW2 battleship vs attacking aircraft. Yeah, the battleship can steam 12,000 nm on one load of fuel, while the planes can only go 1,000 nm or so. But that doesn't matter, because the planes can move faster. Same thing in space, a ship might be able to change it's velocity by dozens of kps, but only at a few m illigee of acceleration, while the KKV can change it's velocity only a few hundred mps, but at tens of mps per second.

==================

Surely this example just demonstrates it is accelleration (read Thrust) that is critical for evasion rather than Delta-V (read ISP).

eg the battleship can go forever but the planes can accellerate a damn sight faster.

Tony said...

SA Phil:

"Sure you can. You are just speaking in generalities."

I'm speaking in principles. You can optimize for this OR that, or you can have mediocre performance in this AND that.

"I can make a Truck that gets good gas mileage and is good at towing."

But not as good at towing as one that is optimized for it, regardless of fuel efficiency.

"I can also use that Truck to generate Electrical power."

You can get the truck's engine to generate electrical power. And it won't do it very efficiently if you run the generator off of the drive shaft. You gotta take the engine out and hook it up to the generator directly for efficient power generation.

"I could even make it amphibious if I wanted, be seaworthy and get decent speed for a displacement hull."

No you couldn't. You could make it amphibious OR get decent speed for a displacement hull by turning it into a boat.

"Now is it excellent at both jobs? As good as specially designed systems? Probably not - but that isn't what I am suggesting.

I am suggesting it can do both jobs requiring less mass than two separate specialized systems."


And that extra mass buys you both an optimized drive and an optimized weapon.

Which is what you want in combat, not something that is mass efficient. No warship ever has been that, or ever will be.

"Those specialized systems which would have to be smaller to have both as separate optimized systems - would actually be less capable than the hybrid system."

"Capable" in combat, means effective, not efficient.

Tony said...

SA Phil:

"You are actually talking about something different.

I was figuring out if it were possible for the ship to evade. You are saying it is a bad idea for it (even if capable) to evade due to mission constraints."


If the mission constraints restrict how much delta-v you can use for evasive maneuvering, then it is not possible to evade outside of those constraints. It's not optional, unless you decide to turn a sruvivable mission into a suicide mission.

"The less operatic the drive the most likely the ship cant do either. But with a demi-torch you might be able to do both - it really depends on all the scenario's assumptions.

You have often suggested fusion drives. Those could be demi-torches in many scenarios."


A PMF fusion drive might possible be a centi-G drive. That wouldn't even be deci-operatic.

Also, if you have operatic or demi-operatic drives on your ships, there's no reason to suspect that you couldn't also have them on your missiles. And, as always, the missile can use all of its delta-v to accomplish its mission. Ships can't.

Tony said...

Locki:

"It seems to me in military history there have always been two approaches to destroying the target.

1. You can use a very small number of precision, high value weapons guaranteed of a hit /kill eg Air to Air Missiles, Torpedoes, Katana


2. Overwhelm the defences with a swarm of cheaper weapons designed to saturate the target eg VLS Aegis Cruiseres, artillary barrage, Longbow arrow storm.

You can choose whichever method you like for your SF setting but both are equally valid. Furthermore considering the mass constraints of a Space Warship I'd suggest the first method is more plausible. It has similar-ish mass issue to warplanes and submarines. Whereas, historically a swarm of missiles is usually used from platforms where mass is not a critical issue (eg surface cruiser. I've never liked the swarm of KKVs scie-fi trope for this reason but I guess an author can choose whichever strategy he likes."


The choice of weapons is based on what is reliable under a given set of combat conditions. In the hammers and eggshells world of PMF space combat, one would expect many, relatively small ships, with as much firepower as possible per ship. Also, KKVs are not missiles, which I agree there would be relatively few of, but submunitions of missiles. There could literally be hundreds per missile.

"Surely this example just demonstrates it is accelleration (read Thrust) that is critical for evasion rather than Delta-V (read ISP)."

Surely that's what I have been saying.

Locki said...

Tony said:

Also, if you have operatic or demi-operatic drives on your ships, there's no reason to suspect that you couldn't also have them on your missiles. And, as always, the missile can use all of its delta-v to accomplish its mission. Ships can't.

==============

It’s an assumption you could make but not necessarily a true assumption. There aren’t too many nuclear powered torpedoes chasing down our Nuke Subs and Carriers nowadays. Furthermore, it wouldn’t be plausible for a military-techno writer to have these type of systems in it. The engineering and economic challenges make them a non-plausible weapon – even in Tom Clancy’s wildest dreams.



Re: ISP vs Thrust for evasion

Surely that's what I have been saying.

=========

Sorry Tony. I probably got you mixed up with a different poster. Its hard to keep track of this topic sometimes.

Anonymous said...

Tony,

Which is what you want in combat, not something that is mass efficient. No warship ever has been that, or ever will be.
==========

Ha! now I know you are either:

A) making things up to "win"
B) not really thinking your comment through.

Design compromises are made for combat machinery, warships, weapons, etc all the time, throughout history.

All the time.

Sometimes it doesn't work out so well (Sgt York)

Other times it gets fixed (Osprey, M16)

Sometimes it works quite well in the end(Sherman Tank)

(SA Phil)

Tony said...

Locki:

"It’s an assumption you could make but not necessarily a true assumption. There aren’t too many nuclear powered torpedoes chasing down our Nuke Subs and Carriers nowadays. Furthermore, it wouldn’t be plausible for a military-techno writer to have these type of systems in it. The engineering and economic challenges make them a non-plausible weapon – even in Tom Clancy’s wildest dreams."

If you can't have then you have to find some other way to fight. Possibly use the torchships as boosters for very fast kinetics.

Anonymous said...

Tony,

But not as good at towing as one that is optimized for it,
regardless of fuel efficiency.
-----------------

Why not? That is exactly what big trucks are designed to do. Both. At the same time.

==========
==================

You can get the truck's engine to generate electrical power. And it won't do it very efficiently if you run the generator off of the drive shaft. You gotta take the engine out and hook it up to the generator directly for efficient power generation.
----------------

Define efficiently? You could boost electrical generation performance significantly from what you normally see in vehicles if you wanted to. And leave the engine in the truck.

Use a staged turbo set up for a kick up idle speed.

Use a smart clutch that disengages most of the parasitic loads.

===========
================

No you couldn't. You could make it amphibious OR get decent speed for a displacement hull by turning it into a boat.
--------------------

Seaworthy, decent speed and amphibious have all been done before.

You are only talking about 5 to 6 knots here.

------------
==============

Not to bog us down in yet another argument that has nothing to do with the PMF ... but in a round about way this is my point.

We are making assumptions about technologies where the specifics aren't given us.

If the compromises are too harsh - the design doesn't make it past the feasibility stage. Which is completely normal.

But the actual compromises aren't known. How could they be? We don't know them any more than we know the design specifics of 23rd century 100 MJ lasers and SCODs.

(SA Phil)

Anonymous said...

Tony,

If you can't have then you have to find some other way to fight. Possibly use the torchships as boosters for very fast kinetics.

============

There are limits on this. Particularly in the Laser-Star Scenario. The Torchship booster would need to deploy before it is in range of the Laser-Star.

Allowing a Laser-Star to effectively screen Torch Ships "fighters".

(SA Phil)

Tony said...

SA Phil:

"Ha! now I know you are either:

A) making things up to "win"
B) not really thinking your comment through.

Design compromises are made for combat machinery, warships, weapons, etc all the time, throughout history.

All the time.

Sometimes it doesn't work out so well (Sgt York)

Other times it gets fixed (Osprey, M16)

Sometimes it works quite well in the end(Sherman Tank)"


Compromises between this optimized system and that optimized system are not the same thing as compromising two systems -- in this case propulsion and firepower -- so that they can kind of do each other's job. Talk about making things up to win...

WRT mass efficiency, we just got through discussing how that compromises efficiency where power generation is concerned. Also, to take an example I am personally very familiar with, the adoption of the M60A3 machine gun was all about mass efficiency. The only problem is they took most of the mass out of the one place that didn't help -- the barrel. So the barrel had less mass as a heat sink, and less surface area (because less mass equals less circumference) for radiating heat. Suddenly we had guns that were easier to hump around, but couldn't fire two hundred rounds without a barrel change, where we used to have guns that were heavier, but at least could go four hundred rounds before overheating. Subsequently, the adoption of the M240G returned the heavier barrel and greater heat resistance.

IOW, the weapon has to be optimized to meet its duty requirements, no matter how much it weighs. In a battleship, that means you have fully capable guns, but if eight of them weigh too much, you go with six, or you install eight fully capable guns, but of a smaller bore diameter (and thuse lighter per gun and round of ammunition). Same thing with engines -- if steam turbines weigh more than reciprocating engines, then you make a bigger ship, if you want to retain certain ration of firepoer/propulsion/protection.

Locki said...

Tony said:

Also, KKVs are not missiles, which I agree there would be relatively few of, but submunitions of missiles. There could literally be hundreds per missile.

================

Presumably the Missile Bus (of which there are only a few) are using expensive high ISP, low thrust engines (eg laser thermal, NTR).

The KKVs are probably using cheaper, high thrust but low ISP chemical rockets.

Could be an interesting evasion equation for the targetted warship if it has a dual mode drive. (eg high thurst low ISP mode, or high ISP but low thurst mode). It could try to "dodge" early by using high thrust manoevers before the KKVs are released from the Bus or it could use its high ISP to try to out (errrr) delta-V the submunitions.

Anonymous said...

Tony,

Compromises between this optimized system and that optimized system are not the same thing as compromising two systems -- in this case propulsion and firepower -- so that they can kind of do each other's job. Talk about making things up to win...

========

Except that I am not necessarily compromising two systems- In space lower mass influences propulsion optimization.

It would depend on the specifics - but it is possible the mass savings will exceed the initial perceived disadvantage of the actual drive.

The Lower mass might also allow me to carry better cooling capacity, which in turn could improve my weapon performance.

-----------
------------

Besides which compromises are made to propulsion and firepower in real weapon systems too!

The Sherman Tank which I already mentioned not only compromised on both it also compromised on armor!

And it was a success.

(SA Phil)

Tony said...

SA Phil:

"Why not? That is exactly what big trucks are designed to do. Both. At the same time."

They're designed to be as efficient as possible while towing a certain load on a road. They're not designed to be as efficient as they could be if they were driving an electrical generator, or even a boat. That's because they have to be geared to handle grades, plus overcome road friction accelerating and just maintaining speed.

IOW, let's not confuse efficiency within type, with absolute efficiency.

"Define efficiently? You could boost electrical generation performance significantly from what you normally see in vehicles if you wanted to. And leave the engine in the truck."

And get less traction performance while doing so. Also, taking power off with a belt or a chain to drive an alternator is simply not as efficient as driving a generator with the crankshaft.

"Use a staged turbo set up for a kick up idle speed.

Use a smart clutch that disengages most of the parasitic loads. "


Which uses more fuel than a standard idle, no matter how you set it up.

"Seaworthy, decent speed and amphibious have all been done before.

You are only talking about 5 to 6 knots here."


Snort. You're tryin to blow smoke up the ass of someone who worked intimately with those vehicles off and on for ten years.

Seaworthy in this case means Sea State 3 or less. It also means special preparation for swimming, particularly greasing seals and openings. And the feakin' things still leak. In addition, the requirement for a certain interior volume leads to very large vehicles, which make consequently large and valuable targets.

Decent speed comes from either a special drive system and power takeoff -- which are nothing but parasitic weight ashore -- or specially designed tracks, which have compromised ashore performance, particularly on paved roads.

Amphibious is a compromise that leads to minimally adequate performance in two different envoronments, but poor performance compared to land or sea optimized vehicles.

"Not to bog us down in yet another argument that has nothing to do with the PMF ... but in a round about way this is my point.

We are making assumptions about technologies where the specifics aren't given us."


Even if speculative, these propulsion and weapon systems have to live in the real world. The entire history of technology tells us that to work effectively, military systems have to be optimized for their particular functions.

"There are limits on this. Particularly in the Laser-Star Scenario."

Stop right there. I don't think laserstars are plausible in any environment, for reasons we have already extensively explored. If you want to convince me, you'll have to use some other argument.

Tony said...

SA Phil:

"It would depend on the specifics - but it is possible the mass savings will exceed the initial perceived disadvantage of the actual drive.

The Lower mass might also allow me to carry better cooling capacity, which in turn could improve my weapon performance."


You're not listening. Military systems aren't designed to be efficient. They're designed to be effective -- and then as efficient as possible. Given the choice between a maximally effective (within practical constraint) gun/drive combination, or a maximally efficient one, I'll take the former every time. Any rational force designer would.

"Besides which compromises are made to propulsion and firepower in real weapon systems too!

The Sherman Tank which I already mentioned not only compromised on both it also compromised on armor!

And it was a success."


The Sherman tank, when introduced, had a hp-weight ratio of 13.2, 76 mm of sloped armor in front, and a 75 mm, 40 cal gun. The roughly contemporary Panzer IVF2 had a hp-weight ratio of 12.5, 80 mm of vertical armor in front, and a 75 mm, 43 cal gun. The big difference? The Sherman weighed 30.3 tons, allowing for a 400 hp engine and more internal space overall, that simply couldn't be shoehorned into the 23.6 tons of the Panzer IVF2.

The Sherman's early success was entirely in being bigger than the competition. That size allowed for sloped armor and a proportionally large power plant. Allied soldiers believed they had the best tank in absolute terms. And, in late 1942 and early 1943, they objectively did.

What caused the Sherman trouble was the German adoption of the Tiger and Panther, both of which were bigger and therefore could have thicker armor and bigger guns. The Tiger had slightly less power proportionally (12.1 hp-ton). The Panther had substantially more (15.4 hp-ton).

But the point is that nobody had a magic bullet for the necessary tradeoffs. If they wanted more effective tanks, in terms of protection and firepower, they made bigger ones, and tried to keep up on mobility. If you look at the history of warships, you get the same dynamic (except that larger ships actuall had speed advantages, and power systems improved in efficiency over time). If you look at the history of combat aircraft, you see a steady increase in size and power, which has supported increases in speed and payload.

In all cases, you see armies, navies, and air forces making tradeoffs between highly optimized systems of firepower, propulsion, and protection. What you don't see are attempts to make one thing do something else. Well, you did see Fisher claiming that speed was armor, and building ships to meet that ideal -- didn't turn out too well.

Locki said...

Besides which compromises are made to propulsion and firepower in real weapon systems too!

The Sherman Tank which I already mentioned not only compromised on both it also compromised on armor!

And it was a success.

(SA Phil)


=============

I have to agree with Tony here. If military history has taught us anything it is that combination weapons are a terrible idea.
The most infamous examples been the pistol swords and pistol halbeards(!). See the links below for the following travesties.

http://www.collectorebooks.com/gregg01/Lot-66.htm
http://www.flickr.com/photos/chartoo/6968731/

They are just a terrible idea. It’d be like having a M-16 with a permanent fixed bayonet.

I was under the impression the Americans knew the Sherman was hopelessly outclassed by the Panther IV and Tigers but persisted in using it because its was too late to retool for a different tank and you could transport a heap of them compared to more modern tanks (?) Pershing. It helped they were reliable as well.

The better analogy would be an old pre-WWII cruiser tank that was trying to be both anti-infantry and anti-tank vs a modern medium tank (T-34) or MBT which is optimised solely for anti-tank with a few extra weapons thrown in for good measure.

jollyreaper said...

It's entirely possible for missile buses to operate smaller versions of the warship drives. It's also possible they use something else that better suits the mission.

Do we have nuclear-powered torpedoes to attack nuclear-powered carriers? No, but it's also unnecessary. We have jet-powered bombers that launch jet-powered cruise missiles. Same propulsion, different platform.

We use solid rocket motors in many missiles because the performance suits the mission.

One other thought is that closing speed isn't about who put on the KE.

If the Martian war fleet is burning towards Earth at 25km/sec and my SCOD's need a minimum of 30km/sec to make it through the defenses, I only have to thrust them up another 5km/sec.

If the Martian war fleet is in Mars orbit, then I have to give my weapons the full 30km/sec myself.

jollyreaper said...

Not to bog us down in yet another argument that has nothing to do with the PMF ... but in a round about way this is my point.

We are making assumptions about technologies where the specifics aren't given us.
-------------------

That's always been my point. We aren't going to get the answers right but we can at least make the answers seem right-ish, regardless of the imaginary technologies involved.

Just a few rules of thumb:

1. Military hardware is going to be more expensive than civilian hardware.
2. Civilian equipment will more likely be optimized for cheap and reliable and military equipment will be optimized for high-performance which can also make it cost more.
3. Any machine purpose-built for one mission will be more efficient than one that tries to multi-class.
4. The realities of budgeting means a military might be stuck multi-classing anyway.
5. Things don't always go as planned. So some four-star may draw up a battle doctrine, weapons fitting those concepts may be designed and produced, but the doctrine may be bad, it may have become outdated, or the next war is a complete surprise and everyone is making it up as they go.
6. There may be an effective set of tactics for employing a weapon but the top brass doesn't employ them that way, either due to stupidity or sheer necessity.

So, we'd expect that an aircraft with rotating engines meant to fly as fast as an airplane but land vertically like a helicopter will be more complex, more expensive, and more troublesome than a similar helicopter or airplane. And this has proven true.

VTOL is really cool and, if there were no trade-offs, every pilot in the world would love to have it. But there are trade-offs and so Harriers are used because Britain couldn't afford American-style super-carriers. If cost is no object and you are trying to fulfill the carrier mission, you want super-carriers and catapults.

So let's say we have the USS Sitting Duck, a PMF destroyer. It's an 40 year old design and the Duck was laid down 20 years ago. Mission creep has led to more equipment being added over the years and the Duck is 15% over her planned mass allotment. This means her total delta-v and acceleration are below spec.

Her main beam weapons were supposed to be a super-duper advancement over the standard design that would be four times better. A destroyer would have the beam punch of a dreadnaught.(Keeping it vague.) The weapons were great when they worked which was seldom. A maintenance nightmare, they were withdrawn from the fleet. The Duck mounts conventional beam weapons but her reactor was designed with the power requirements of the bigger weapon in mind.

I haven't mentioned a damn thing about specific PMF or operatic technology but everything about the Duck has the ring of plausibility.

Locki said...

jollyreaper said...

Do we have nuclear-powered torpedoes to attack nuclear-powered carriers? No, but it's also unnecessary. We have jet-powered bombers that launch jet-powered cruise missiles. Same propulsion, different platform.

We use solid rocket motors in many missiles because the performance suits the mission.

One other thought is that closing speed isn't about who put on the KE.

If the Martian war fleet is burning towards Earth at 25km/sec and my SCOD's need a minimum of 30km/sec to make it through the defenses, I only have to thrust them up another 5km/sec.


You can choose whatever drive you’d like for a missile bus that makes your story interesting while maintaining the illusion of plausibility. I’m just pointing out its perfectly reasonable the missiles have to use an inferior drive to the starships because of economic or engineering problems. This is backed up by historical precedents.

A better example would be the nuclear powered bombers planned in the 60s. They theoretically could have given you a mach 3+ bomber that could stay airborne for months but it just wasn’t practical economically or from an engineering point of view. It didn’t help the exhaust was radioactive either. The soviets in their paranoia actually made several test flights - sadly the test crews all died horribly months later.

I’d like to point out actually launching a high performance, unshielded, nuclear powered missile bus could be hazardous to the crew! (presumably it needs solid bosster rockets to get it to a safe distance 1st).

Wrt 30km/sec closing speeds. Hitting anything short of Texas at this colossal speed could be optimistic in a near future setting. We can’t even hit things at 3km/sec (NMD is 0 from 7 attempds)with current technology. I assume doubling the closing speed makes things at least 8 times as hard (eg 2 x 2 x 2 b/c it is 3-dimensional).

TOM said...

Well, in an operatic setting, i would say, that warp drives are unviable for missiles, so they needs to be launched from close range - but they can still make big acc for short times.

So i also think, simply outrun a missile that was designed to hit a fighter has got low chance although atmosphere and hide behind in low orbit can help.
But i rather think in attack the main bus, then endure some /hopefully not fatal/ punishments from shrapnels.

However one of my point is : a missile bus can kill a frigate, or a fighter, but you have more fighters, and i find unlikely that the warheads of a missile bus could attack multiple targets, low delta-V, poor aim /calculation of proper course/, no las boost from launch platform etc.
I can hardly imagine battle against PDF without charging ships, they have the more resources, you only have the advantage of gravity well, and agility, you have to rush them with all you got, then deploy occupy forces.

jollyreaper said...


You can choose whatever drive you’d like for a missile bus that makes your story interesting while maintaining the illusion of plausibility. I’m just pointing out its perfectly reasonable the missiles have to use an inferior drive to the starships because of economic or engineering problems. This is backed up by historical precedents.


True. It comes down to just what you can afford to treat as expendable. And we're right back to the original purple/green discussion with a laserstar. If the laserstar costs x and you have to spend close to half of that on kkv buses to saturate the defenses, then that's going to constrain the enemy's flexibility. Laserstars can shoot at anything but KKV's are a one-trick pony.

Comparing it to modern weapons, why do we sail a giant carrier battle-group instead of just fitting out a sub with a hundred cruise missiles? Well, actually we have done the sub thing now but those are fire-once weapons. The carrier can conduct many combat sorties reusing the aircraft.

With current doctrine, if the enemy has ridiculously effective air defense, cruise missiles would be used as stand-off weapons. Let the robots die. Degrade defenses enough, then manned aircraft can finish up. It costs more to kill a target with a cruise missile than a fighter-bomber, though fighter-bombers aren't cheap.

If high-performance drives really are expensive, then bus recovery might be worth the effort, even though it might take months to get them back. You win the battle, you get to collect the buses later. Lose and it doesn't matter.

One of the things I thought was interesting in the Praxis trilogy is that the missiles there had scaled down versions of the operatic torches used by the warships. Missiles were the primary weapon and launched in macross-style swarms. Missiles that didn't hit targets would swing around for recovery after the battle.

The Praxis setting is what I would call real-ish -- there's a hard, candy shell on the outside but it's all creamy nougat inside, soft SF if you probe too deeply. But for anyone coming from a Star Trek or Star Wars background, it'll seem diamanoid-hard. :)

jollyreaper said...


You can choose whatever drive you’d like for a missile bus that makes your story interesting while maintaining the illusion of plausibility. I’m just pointing out its perfectly reasonable the missiles have to use an inferior drive to the starships because of economic or engineering problems. This is backed up by historical precedents.


True. It comes down to just what you can afford to treat as expendable. And we're right back to the original purple/green discussion with a laserstar. If the laserstar costs x and you have to spend close to half of that on kkv buses to saturate the defenses, then that's going to constrain the enemy's flexibility. Laserstars can shoot at anything but KKV's are a one-trick pony.

Comparing it to modern weapons, why do we sail a giant carrier battle-group instead of just fitting out a sub with a hundred cruise missiles? Well, actually we have done the sub thing now but those are fire-once weapons. The carrier can conduct many combat sorties reusing the aircraft.

With current doctrine, if the enemy has ridiculously effective air defense, cruise missiles would be used as stand-off weapons. Let the robots die. Degrade defenses enough, then manned aircraft can finish up. It costs more to kill a target with a cruise missile than a fighter-bomber, though fighter-bombers aren't cheap.

If high-performance drives really are expensive, then bus recovery might be worth the effort, even though it might take months to get them back. You win the battle, you get to collect the buses later. Lose and it doesn't matter.

One of the things I thought was interesting in the Praxis trilogy is that the missiles there had scaled down versions of the operatic torches used by the warships. Missiles were the primary weapon and launched in macross-style swarms. Missiles that didn't hit targets would swing around for recovery after the battle.

The Praxis setting is what I would call real-ish -- there's a hard, candy shell on the outside but it's all creamy nougat inside, soft SF if you probe too deeply. But for anyone coming from a Star Trek or Star Wars background, it'll seem diamanoid-hard. :)

Anonymous said...

RE: Tony

Slanting all my examples with strawmen is really not applicable to this discussion. There are a lot of incorrect statements in all of that, but they are all off topic.

Regarding optimization - I think you are throwing up a major Red Herring. You don't design for a level of "optimization" - you design for a level of performance.

The hybrid system would also be optimized for its dual role. If its optimization was insufficient to meet its performance requirements compared to two separate alternative systems it would not be used.

Every single piece of military hardware (and non-military) involved multiple compromises.

(SA Phil)

Anonymous said...

Locki,

I have to agree with Tony here. If military history has taught us anything it is that combination weapons are a terrible idea.
The most infamous examples been the pistol swords and pistol halbeards(!). See the links below for the following travesties.

=============

Except this is a bit different.

It is combining a particle beam weapon and an electric drive system. Both of which are specialized systems designed to accelerate charged particles.

Presumably to replace a warship niche that mounted a particle beam weapon and an electric drive.

It isn't a combination weapon - it is commonizing mass intensive parts between two systems designed to do similar things.

If particle beams make no sense in the setting - it doesn't exist.

If electric drives make no sense on warships - it similarly doesn't exist.

(SA Phil)

Anonymous said...

Tony,

You're not listening. Military systems aren't designed to be efficient. They're designed to be effective -- and then as efficient as possible. Given the choice between a maximally effective (within practical constraint) gun/drive combination, or a maximally efficient one, I'll take the former every time. Any rational force designer would

===============

Which one of us isn't actually listening?- I am suggesting they would use the system that would give them closest to the desired performance characteristics.

You are suggesting they would rather stick to "optimized" systems even if the alternative gave a better fit for the target performance.

You can't "know" that the combination system won't do that - There is no data, there isn't even any math. Again you are making assumptions based on generalities.

"principles"? please. There is no principle that says this undefined electrical grid device or that unspecified magnetic field device can't accelerate that undetermined charged particle.

(SA Phil)

Anonymous said...

So .. another concept could utilize a system similar to a Plasma Wakefield accelerator.

http://en.wikipedia.org/wiki/Plasma_wakefield_acceleration

This one is actually rather simple. The drive mode would simply exhaust the plasma at some point of the process using it directly as thrust.

In weapon mode, it would continue to generate the Plasma Wakefield to accelerate the particles.

Since this concept always uses an accelerated plasma anyway - in the interest of a more effective particle accelerator design - all I am suggesting is two different uses for the plasma.

(SA Phil)

Rick said...

Congratulations to everyone for a record breaking thread! Which seems to be headed for the 1000 level ...


It is easy to adapt a propulsion system so that it can function as a weapon: Just run it up to high speed and slam it into a target. :)

Which is another way to say that Tony probably has the best of this particular sub-debate. Though some graciousness wouldn't hurt the argument.

Now, it might turn out that if you can build a torch-level drive at all, or even a sub-torch, tightly focusing the exhaust stream is easy to do.

But I think people have been seduced by Niven and the general fact that torch-level drives put out terawatts of power.

In practice, even the drive and a particle beam weapon operate on the same principles, they would probably have about the same engineering relationship as a diesel engine and a machine gun. (Same principles: hot gas driving a piston, with some power captured to sustain cyclical firing.)

That said, probable != inevitable. And there is at least one exception that has come up in this thread. IF you have laser thermal propulsion, you necessarily have lasers capable of sustained blowtorch zapping, probably out to thousands of km.

This is certainly a laserstar-class installation, and could be readily adapted to serve as a powerful defensive weapon in a pinch. How you would deploy a fully weaponized version is a separate question.

Tony said...

SA Phil:

"Slanting all my examples with strawmen is really not applicable to this discussion. There are a lot of incorrect statements in all of that, but they are all off topic."

There ain't a straw man in there. Phil, and you know it. Nor is there an incorrect statement that I'm aware of. So correct me if I'm wrong -- if you can. Trying to dodge by invocating a desire to avoid derailing the discussion is just cheap.

"Regarding optimization - I think you are throwing up a major Red Herring. You don't design for a level of 'optimization' - you design for a level of performance."

Yes, which leads to highly optimized systems. No red herring there.

"The hybrid system would also be optimized for its dual role. If its optimization was insufficient to meet its performance requirements compared to two separate alternative systems it would not be used."

Pure, unadulterated, doubletalk. There's no such thing as optimizing for a dual role. Making a system work in two different roles involves compromises that go against the whole philosophy of optimization.

"Every single piece of military hardware (and non-military) involved multiple compromises."

Yes. But the compromises are between how much of this or that to put in the final design, not compromises of performance within this or that.

Anonymous said...

Tony,


There ain't a straw man in there. Phil, and you know it. Nor is there an incorrect statement that I'm aware of. So correct me if I'm wrong -- if you can. Trying to dodge by invocating a desire to avoid derailing the discussion is just cheap.

==========

Bla - I typed it all up and clicked publish but it seems to have died in transit - T-storms here. Maybe it is better this way. Maybe it will reappear. Who knows. I will instead respond in a less confrontational manner.

You probably are not aware how snippy and nasty your comment comes across to me. You come off like a bully daring me to knock a block of wood off your shoulder.

===============

Most of your inaccuracies come from assuming I was claiming that you could add features to this example truck without compromising it in some way... if you look back .. you will see I never said that.

The most glaring inaccuracy was about losing fuel economy by developing a "power idle" mode for making electricity. That is exactly the point. You need to burn fuel to make power -- without the power you cant make electricity.

You can always drop back down to a normal idle when not making the power.

==========

There were several shapes and sizes of strawmen in there. You had the part where you invoked a Specification I didn't say anything about and then claimed I couldn't meet it. That is a classic strawman ploy.

You had the part where the truck designed for fuel economy and towing wouldn't be optimized for other things -- things which you added to make your point. Another strawman.

---------

I am not going to type it up point for point again - if you want to continue to play schoolyard bully be my guest.

(SA Phil)

Anonymous said...

Rick,


But I think people have been seduced by Niven and the general fact that torch-level drives put out terawatts of power.

---------

I actually have not read that book. I have read two Niven books Ringworld, and one about a detective with a sort of telekinetic ghost arm.

I think a lot suffered in my presentation - immediately assumptions were made that I thought that you could adapt a current electric propulsion system to fire particle beams. Rather than a system that would be designed to do both from the outset.

My thought is the weapon side would be the more demanding of the two since it would take the most power.

I also wonder at all this drive performance this warship would supposedly lose? Lets say the difference is between 0.010 and 0.015 gees of acceleration - does electric drives lack of performance not automatically give you wiggle room?

Line of Battle Ships were slower than frigates - were they not? They should have been faster given their length. I guess given the nature of their propulsion systems there was some performance wiggle room.

(SA Phil)

Anonymous said...

Now that I think about it - why use nuke-electric at all? Keep your nuclear power-plants on the "ground"

Switch to Laser Thermal across the board. And use Laser Photo Voltaic for power.

You wouldn't need huge solar panels with beamed PV, you could use specially designed semi-conductors that were "optimized" (heh) for conversion efficiency at the Power Laser's wavelength.

Your Laser Thermal Laser could be IR, your Laser Power Laser could be high blue. That keeps heat manageable at all times. Less turbines, less cooling headaches, less vibrations.

Since you could then have multi-megawatt ships with no on-board reactor - you could mount any high energy weapon your tech could manage. Even a Laser.

The ultimate specialist- a Laser-Star which is both driven and powered by lasers.

Of course the invading fleet would have a problem. It doesn't have the equivalent Laser Thermal or Laser Electric capabilities. It is stuck trying to haul massive nuclear reactors around. It is bringing a broken down mule to a horse-race.

Might be better off accelerating hordes of missile busses from home.

(SA Phil)

Anonymous said...

Either that or I suppose the invaders could have Laser-Mega-Stars, which are essentially nuke-electric Laser-Star Propulsion/Power carriers.

They serve as tugs for a fleet of LTLP Laser-Stars and LTLP Scout/Attack craft. They then launch their parasites and then serve as the Laser-Thermal and Laser-Power sources for the invading fleet.

That is no moon .. it is a space station (sort of)

(SA Phil)

Tony said...

SA Phil:

"You probably are not aware how snippy and nasty your comment comes across to me. You come off like a bully daring me to knock a block of wood off your shoulder."

Oh, I'm aware of it...to the same degree that you should be aware how bullying your accusations of straw men are. (Not because it's wrong to point out logical fallacies, but because it's a cheap and passive-aggressive trick to claim them, then not engage them directly.)

"Most of your inaccuracies come from assuming I was claiming that you could add features to this example truck without compromising it in some way... if you look back .. you will see I never said that."

Quite frankly, Phil, it seems to me that you're being deliberately vague and just moving the goalposts. Thanks for the following example:

"The most glaring inaccuracy was about losing fuel economy by developing a 'power idle' mode for making electricity. That is exactly the point. You need to burn fuel to make power -- without the power you cant make electricity.

You can always drop back down to a normal idle when not making the power. "


We were talking about efficiency. Somehow using an idling drive engine is an efficient way of generating electricity. No, it's just an inefficient way to generate electricity using an available power source.

"There were several shapes and sizes of strawmen in there. You had the part where you invoked a Specification I didn't say anything about and then claimed I couldn't meet it. That is a classic strawman ploy."

Wait...what? What specification did I invoke? Where? The only specific design I talked about was amphibious tractors, something I apparently know a lot more about than you do.

If that's what you're talking about, you simply don't know what you're talking about.

If it isn't what you're talking about, you need to explain where you perceived a reference to a specification.

"You had the part where the truck designed for fuel economy and towing wouldn't be optimized for other things -- things which you added to make your point. Another strawman."

I never said anything of the kind. I said that a truck can be optimized for towing, but that it couldn't be optimized for fuel economy, except in comparison to similar towing vehicles.

"I am not going to type it up point for point again - if you want to continue to play schoolyard bully be my guest."

Hey, let's make up our minds right now that I'm not here to bully you or anybody else. If you perceive a challenge, it's a challenge to actually articulate what you're trying to say, instead of throwing around insulting claims when I disagree with you.

"My thought is the weapon side would be the more demanding of the two since it would take the most power.

I also wonder at all this drive performance this warship would supposedly lose? Lets say the difference is between 0.010 and 0.015 gees of acceleration - does electric drives lack of performance not automatically give you wiggle room?"


What I think you're missing is that an electron or proton gun isn't simply an electron or proton gun. When it is optimized to be a weapon, well that's what it behaves like. When it is optimized to be a propulsion system, that's what it behaves like. When it is designed to do both, it does neither well enough to be considered effective in a military sense.

"Line of Battle Ships were slower than frigates - were they not? They should have been faster given their length. I guess given the nature of their propulsion systems there was some performance wiggle room."

Different hull forms, Phil.

Anonymous said...

Tony

(more aggressive crap)

Quite frankly, Phil, it seems to me that you're being deliberately vague and just moving the goalposts. Thanks for the following example:

=========

I was being vague because I am trying to avoid a pedantic discussion about truck design. This isn't the truck design blog.

You have got me like this several times in the past, even where I show you are wrong in this or that assumption -- you will deliberately drag the discussion out until it is beyond absurd. You are like a shark, when you think you smell blood you attack- I am done humoring you. Just call the example pointless and move on.

I went into a lot of detail and the dog ate my homework which I mentioned - but honestly it wasn't worth it.

You are starting it up again - if you feel insulted you should step back find a mirror and look at all the people you insult on a regular basis.

(SA Phil)

Tony said...

SA Phil:

"I was being vague because I am trying to avoid a pedantic discussion about truck design. This isn't the truck design blog."

Sounds like a convenient excuse, Phil. Not that I think you're making excuses -- just want to point out that you're "starting it up again", to borrow a turn of phrase.

"You have got me like this several times in the past, even where I show you are wrong in this or that assumption -- you will deliberately drag the discussion out until it is beyond absurd. You are like a shark, when you think you smell blood you attack- I am done humoring you. Just call the example pointless and move on."

Thing is, Phil, when you think I'm wrong, what it usually is is that we're talking past each other. You seem to be very literal and focussed on just what you want to say, and provide illustrations that work in your mind. They don't always work in other people's minds. Often, they don't even make sense, at least not to me.

"You are starting it up again - if you feel insulted you should step back find a mirror and look at all the people you insult on a regular basis."

Of course. Tony is always wrong, Phil is just misunderstood.

Thucydides said...

The argument about multi purpose trucks was just silly; we have real life examples like the DUKW or LVTP-7. They exist to fit special niche roles, but a 6X6 truck of the same period had better load carriage and performance than the DUKW, and in a stand up fight, the LVTP with its barn like proportions and limited fire power would be chewed up by any modern IFV. Of course, you still have to deal with a platoon of dismounted Marines...

I really can't think of any circumstance or niche that would make a dual mode drive/particle beam weapon useful; amphibious vehicles have utility in special circumstances, and the more they tend towards boats, the less they are useful outside the water. Canadian Forces LAV's never swam very well (being designed as wheeled fighting vehicles), and the swim modifications were removed a long time ago to add more protection and fuel.

Locki said...

I think a lot suffered in my presentation - immediately assumptions were made that I thought that you could adapt a current electric propulsion system to fire particle beams. Rather than a system that would be designed to do both from the outset.
My thought is the weapon side would be the more demanding of the two since it would take the most power.
(SA Phil)


====================

I have to admit whenever I hear words like "dual use propulsion and beam weapon" Intuitively I assume dual purpose is an engineering compromise of nightmare proportions. For propulsion and weaponary the purposes are vastly different and the compromises too high.

I will grant you a particle beam designed primarily as a weapon may give you a small boost in propulsion if it is fired at very low power. It may work. I think a particle beam designed primarily as an engine would be an absolutely terrible weapon.

Besides, I was also put further offside, since from my reading of it particle beam weapons are just terrible weapons in general. I'd rather wage battle with my neutrino cannons, japanese pop songs or my light-sabre weilding space Jesus.

I'll accept if someone can create a good particle beam cannon it may give you a small, relatively efficient boost as a propulsion engine. And its kinda mass free since you are already hauling around a giant-ass synchotron or whatever.

Now that I think about it - why use nuke-electric at all? Keep your nuclear power-plants on the "ground"

Switch to Laser Thermal across the board. And use Laser Photo Voltaic for power.

You wouldn't need huge solar panels with beamed PV, you could use specially designed semi-conductors that were "optimized" (heh) for conversion efficiency at the Power Laser's wavelength.


======

Now this I can live with :).

This brings me to the 2nd question. How efficient is laser thermal supposed to be? Experimentally we've never done much with it. Will it only work if we assume we have unlimited free energy (solar, nuclear) and don't care about efficiencies?

The targetting issues we discussed earlier are also going to apply to laser thermal. Its going to be a pain hitting your own craft continuously past about 150,000km. Practically impossible in fact.

From an engineering point of view low mass, high efficiency, zero-G nuclear reactors that can operate in a vacuum have never been proven in any size either. It could be a serious pain.

Some problems off the top of my head

a. Large nuclear reactors are probably the one element of our PMF warships that doesn't really lend itself to modular, zero-G assembly. You'll have to boost it up in one go. So the size of your laserstar is constricted by your lift capacity back on earth. I guess you could send up multiple small reactors but this is going to make hitting that 1kw/kg magic threshold a really huge challenge.

b. I ain't going to be in the same state as the rocket boosting an unsheilded, super high performance nuclear reactor

c. The nuclear jet engine programs basically all failed for a whole variety of social/political/miltiary/environmental reasons. And they effectively had unlimited propellent (air) and a free radiator. Its more than plausible nuclear reactors in spaaaace will never be worth developing either.

d. How do you safely boost an unshielded super high performance reactor into space anyway? Presumably its sent up there "cold" but the radiactivity is still going to be a pain.

TOM said...

"In practice, even the drive and a particle beam weapon operate on the same principles, they would probably have about the same engineering relationship as a diesel engine and a machine gun. (Same principles: hot gas driving a piston, with some power captured to sustain cyclical firing.)"

How about comparing them to flamethrower and gasoline engine?
Or water cannon and water-jet engine?
Maybe they could have the same motor, although focusing the beam is more difficult than simply exhaust it.

Tony said...

TOM:

"How about comparing them to flamethrower and gasoline engine?
Or water cannon and water-jet engine?
Maybe they could have the same motor, although focusing the beam is more difficult than simply exhaust it."


I think the problem is scale. A propulsion engine is a large machine, optimized for a moderate level of work over long time periods, while a weapon is a relatively small one optimized for very high levels of work over a very short time periods.

Tony said...

Thucydides:

"...in a stand up fight, the LVTP with its barn like proportions and limited fire power would be chewed up by any modern IFV. Of course, you still have to deal with a platoon of dismounted Marines..."

Which is why you don't use an AAV (Armored Amphibious Vehicle, which is the 90s-forward nomenclature of the LVTP) in a stand up fight against IFVs. It's optimized to be an amphibious transport, to get the troops ashore, then transportthem around. In combat you dismount the troops and let them do the fighting. In the context of the US Marine Corps, you also have air support, TOW missiles on HMMWVs, and artillery to fight enemy IFVs.

The relevance to the conversation in general is that when you optimize for one thing, you can't expect it do something else very well. Staying with the infantry carrier example, and IFV is almost an anti-AAV in terms of optimization. It's designed to be a light AFV killer first, and an infantry carrier second. So, while an AAV can carry up to 20 passengers, it would have to get very lucky to kill an enemy IFV with its machine guns. And IFV, on the other hand, can deal with enemy IFVs, but can only carry up to 8 dsimounts, and many carry only 6 or 7.

jollyreaper said...

I really can't think of any circumstance or niche that would make a dual mode drive/particle beam weapon useful;

I think the real question is whether a drive can have an efficient cruise mode and a tactically-useful afterburner mode for dodging.

My gut feeling is that the warship will expend proportionately more fuel than the KKV to change position -- in other words, KKV can follow every move. So you weigh the mass of whatever is necessary to provide "afterburner" mode, plus the mass of fuel burned, plus required number of jinks to defeat a KKV swarm and compare all that AGAINST the cost of active defense systems to defeat the swarm.

My gut feel on this is that there's no such thing as evasive action. That sort of thing was really cool in WWII, though, where a ship could "comb" the tracks of incoming torpedoes. That's really cinematic and dramatic, especially with the ship heeling over hard and seeing the crew leaning against a 30 degree list.

A point raised in TSTS is that a hit on a warship might not be an insta-kill. What most people are thinking of right now is test footage of modern-day cruise missiles and torpedoes literally ripping ships in half. Youtube has the videos. The rule of thumb seems to be if any weapon hits home, you are mission-killed if you are lucky -- out of the fight, limp back to base for repairs -- and if you aren't lucky the ship's gone under in five minutes.

If the shrapnel can't deliver energy efficiently, it might poke a hole through the ship without disabling it.

For drama's sake it's certainly better for ships to be able to take a few hits while remaining in the fight. But I think this might even be something we could answer, generally speaking. If a PMF warship is going to have more than half it's mass as reaction mass, is gangly and spindly... the other question is the shield. If most shots are going to be coming from the front, the whipple shield does double duty, both for navigation and combat.

TOM said...

I wondered on the possibility, that the thrusters of the ship could fire ions with very high speeds, at the magnitude of ten or hundred thousand km/s, so it can drag less amount of propellant.
/Sorry i am not an engineer, i dont know how much amount of magitech is needed to do that/
So there would a central cyclotron to accelerate the ions. Then the particle cannon strips a bit of this ion stream, and pumps it into a small focusing barrel.
A river can be faster in a tight canyon, while slower in wide open, so the pressure would accelerate a small number of ions to relativistic speeds.

Maybe i got too much fantasy, but again, i could compare it to a mechanism, that pumps (part of) a ship's water jet stream through a tight pipe, to make a water cannon.

Tony said...

TOM:

"I wondered on the possibility, that the thrusters of the ship could fire ions with very high speeds, at the magnitude of ten or hundred thousand km/s, so it can drag less amount of propellant.
/Sorry i am not an engineer, i dont know how much amount of magitech is needed to do that/
So there would a central cyclotron to accelerate the ions. Then the particle cannon strips a bit of this ion stream, and pumps it into a small focusing barrel.
A river can be faster in a tight canyon, while slower in wide open, so the pressure would accelerate a small number of ions to relativistic speeds.

Maybe i got too much fantasy, but again, i could compare it to a mechanism, that pumps (part of) a ship's water jet stream through a tight pipe, to make a water cannon."


Well, you could take some relatively hp water off the downstream side of the impeller, but you wouldn't be using the waterjet as a gun, and you decrease the reliability of the waterjet mechanism. (More stuff = more stuff that can go wrong.) What you really want is a dedicated seawater pump, feeding a dedicated hp water circuit, like on a fire boat.

WRT high exhaust velocity, yes, in principle it would be a good thing, but the rule of thumb is that higher velocities equal lower thrust. This isn't for fundamental reasons but for engineering ones. Given a certain amount of gigawatt hours of power, you can move a lot of stuff relatively slowly, but with a lot of immediate force (chemical rocket engine), or you can move a little stuff really fast, but with little immediate force (electric rockets). If you want to move a lot of stuff very fast, you have to have a whole bunch of energy. That's when you get inot magitech.

Tony said...

jollyreaper:

"A point raised in TSTS is that a hit on a warship might not be an insta-kill. What most people are thinking of right now is test footage of modern-day cruise missiles and torpedoes literally ripping ships in half. Youtube has the videos. The rule of thumb seems to be if any weapon hits home, you are mission-killed if you are lucky -- out of the fight, limp back to base for repairs -- and if you aren't lucky the ship's gone under in five minutes.

If the shrapnel can't deliver energy efficiently, it might poke a hole through the ship without disabling it."


Even if a hit isn't an insta-kill, when you're talking about the pmf hammers and eggshells-verse, any hit is very likely to be a mission kill. We have to remember that a SCOD is not actually a soda can. It probably masses a few kilograms, even dry. At even 5 kps of relative velocity, that's like setting off 2.5 kg of TNT within the target for every kilogram of SCOD mass.

That might not destroy the ship outright, but it would definitely take out any critical systems in the vicinity of the hit. Ando n a PMF ship, every system is critical, or it wouldn't be there.

"For drama's sake..."

For drama's sake, the realistic consequences of surviving a hit is how are we going to get home with our (pick one) propulsion, power, life support, airtight integrity, weapons catastrophically compromised?

TOM said...

Yeah good argument against manned fighters, although i wonder that in orbital combat, maybe some squadron leaders should be manned to be prepared for any surprises, espacially on the other side.
I think the best option is that only the front is ruined with the weapons systems, and some manuevering thrusters, then it is a waste to execute a disabled fighter.
Well if the enemy would use laser for defence, most times, mission kill would only mean blindening, and injury of delicate electronics, better chance for return.

TOM said...

Back to manned fighters from a writer's perspective, i wondered on the following : what people really like in fighting?
Duels. Not die from a barrage or a guided missile, sniper, but duel is the form of fight, that can be said to be somewhat noble.
How it can be possible to bring back duels, if not by the actions of aces??

Maybe mechas duel in a city?

In Hyperion they found out a codex called new Bushido, that armies should duel on a location, that spares civil lives.

Maybe there could be some ritualized combat between noble enemies, while lowly enemies who dont respect this, should be blasted away?

jollyreaper said...

Ritual combat is a way to keep swords and starships. And you are right, swashbuckling is romantic while getting cut down in an artillery barrage is not. So you have flower wars with internal rivals and total war against external threats. But that sort of situation falls apart when the flower war loser does not concede gracefully.

Nick P. said...

Blogger is whining at me, so I'm splitting this up.


a. Large nuclear reactors are probably the one element of our PMF warships that doesn't really lend itself to modular, zero-G assembly.

You'll have to boost it up in one go. So the size of your laserstar is constricted by your lift capacity back on earth. I guess you could send up multiple small reactors but this is going to make hitting that 1kw/kg magic threshold a really huge challenge.


That would entirely depend on what kind of reactor we're talking about. If I was designing a space based reactor the absolute LAST place I would start is trying to space-ify a pressurized water reactor.

Personally, I'd go with a fast reactor cooled by something like sodium or NaK. That would give you a much, MUCH more reasonable vapor pressure to work with. Then rather than a giant foot thick solid pressure vessel you could assemble the thing out of comparatively thin plates and what-have-you.

Stainless steel, carbon composite nano-whatsit, take your pick.

You also get the bonus of pumping the sodium (or NaK) electromagnetically, meaning your reactor coolant loop has virtually no moving parts and the reactor itself very few (pretty much just the reactivity controls).


b. I ain't going to be in the same state as the rocket boosting an unsheilded, super high performance nuclear reactor


If you say so, more commentary further down.

Nick P. said...

Continued:


c. The nuclear jet engine programs basically all failed for a whole variety of social/political/miltiary/environmental reasons. And they effectively had unlimited propellent (air) and a free radiator. Its more than plausible nuclear reactors in spaaaace will never be worth developing either.


A few drive-by points, if I may.

First we already have built and launched space reactors before and there's talk of it being done again. Granted nothing near as large as what we're talking about but the concept isn't the naive mistake of the 60's relegated to the dustbin.

Space nuclear reactors and nuclear jet engines are two different things and should be treated as such.

Second, you do need them if you want to get anything done in the outer solar system. Now granted we can argue back and forth all day till we're blue in the face about where most activity will be in the PMF and if the issue will even come up, but if a setting or story involves the mighty Solar Empire Planet Cruiser Agamemnon going out to stomp on the unruly miscreants of Titan then it's going to be a problem.

Third, it's still not cut-and-dried to me that a giant gossamer array of paper thin solar cells is going to be more reliable and survivable than radiators. You sure as hell aren't going to be trying to dodge KKV's on a ship equipped with them.

...or CHEAPER for that matter. When we start talking about the exorbitant costs of reactors on Earth you run smack dab into protesters and activist groups stretching out planned construction from the planned on two years...to five...or ten...and so on so forth. When you've borrowed a couple billion dollars, hired a construction crew of thousands and are jumping through regulatory hoops (Fun fact: NRC regulator time is billed at more than $200 an hour and there is no upper limit to how much dithering they can charge you for!) then any delay with this sort of barratry will rapidly cause costs to balloon.

Will this be a problem or not for space reactors? That again depends on your setting, if people in the future are as radiophobic and sue happy as they are now it might be. If they've gotten over that then maybe not.

It's also worth note that while commercial power plant construction has stalled here in the US at least the military has been happily continuing to produce nuclear powered ships and submarines. I could also plausibly believe that holding true in the future, where civilian vessels are solar powered and the military builds whatever-the-hell it wants.

Nick P. said...

Finally:


d. How do you safely boost an unshielded super high performance reactor into space anyway? Presumably its sent up there "cold" but the radiactivity is still going to be a pain.


I'd send the reactor up unfueled, and later on or mixed in with other component shipments during construction send the fuel up bit by bit. In the example reactor I outlined above the fuel would be highly enriched uranium, so if we're launching a fuel bundle or two at a time it would be in a nice sturdy box so that if the cargo rocket does go tits-up then it'll land in the ocean in one piece.

Oh well, send a boat, fish it out, move on.

As far as radioactivity goes U235 is a mild alpha emitter with a half-life of more than 700 million years (which is to say, not very radioactive at all). Unless you ingest it there's not much threat from radioactivity and even then I'd probably be more worried about the fact it's a somehwhat toxic heavy metal.

If somehow our sturdy box fails and the fuel element breaks up then you take advantage of the fact that radioactive materials are nice enough to tell you where they are and go pick up the larger peices.

Having said all of that, from an engineering and saftey perspective I don't really see what the problem is. From the political and social side of things that's a question I can't answer, as it depends on the attitudes, beliefs and knowledge base of the population in question within your story setting.

Nick P. said...

And one post doubled, of course.

Rick said...

The duplicate post has been zapped.

I think that, given politics that support sending it up at all, the reactor core could probably go up safely as one heavy lift payload. Even if you need a launch site in the middle of nowhere.

But it is hard to imagine that it would be cheaper than solar electric, which essentially has no moving parts. Nuke electric is, fundamentally, a steam engine in SPAAACE !!!

Unfortunately it is pretty much the only way to get past Mars, or best the asteroid belt.

Tony said...

TOM:

"Back to manned fighters from a writer's perspective, i wondered on the following : what people really like in fighting?"

The question has to be asked -- are we talking about real combatants, or the readers of fiction? Real combatants, except for the few adrenaline junkies out there, really like fighting to be over with as quickly as possible, preferably without them dead or severaly injured. Readers of fiction like long, drawn-out action sequences.

"Duels. Not die from a barrage or a guided missile, sniper, but duel is the form of fight, that can be said to be somewhat noble.
How it can be possible to bring back duels, if not by the actions of aces??"


The duel is a trope that, oddly enough, has survived into industrialized warfare. But it has morphed into the "artillery duel", or "tank duel" or "battleship duel" or (everyone's favorite) the dogfight. The porblem for storytellers is that these so-called duels are really the acts of organizations squaring off symmetrically against other organizations -- even a tank is fought by its crew, with crew organization and training often a decisive factor; even single seat aircraft are projected into the air by large organization -- without the interference, at least temporarily, of complementary forces that actually do exist.

So, for example, when tanks duel, we don't want infantry, artillery, or antitank weapons intervening. When battleships duel, the destroyers and cruisers should be happy to fight each other, and aircraft and submarines should be far away. When artillery duels, let's not have aircraft or major ground actions screwing up the environment. When fighter pilots duel, there should not be antiaircraft shells or missiles flying around, nor should one side be grossly outnumberd by the other. (Even if the planes have substantiall different capabilities, the strengths and weaknesses should be complementary, so that pilot skill is still an issue.)

So the duel still exists, kind of, under the right circumstances, without having to invoke any unlikely or implauible constraints. The writer and reader just have to accustom themselves to the fact that the story is told from the viewpoint of a unit commander, a tank crew, or a ship's captain, with maybe insterspersed vignettes of how the artillery crews fight, how each crewman acts and reacts to the changing situation, or how different departments on the ship deal with the circumstances of battle.

"Maybe mechas duel in a city?"

Yeah, that's never been done...

"In Hyperion they found out a codex called new Bushido, that armies should duel on a location, that spares civil lives.

Maybe there could be some ritualized combat between noble enemies, while lowly enemies who dont respect this, should be blasted away?"


As jollyreaper pointed out, that only works up to the point that somebody decides it's too his best advantage to break the convention. Also, as noted recently several antrhopoligists and military historians, underneath the ritualistic combat of flower wars, there is always a culture of ambush, raid, and individual murder.

TOM said...

"The question has to be asked -- are we talking about real combatants, or the readers of fiction? "

I talked about writer's perspective.
(Well i knew a guy, behind their back others joked that he goes to Iraq, because there, ha gets a medal for killing someone... )

Of course i am aware if one dont respect the ritual, there will be normal war, but it could be an interesting plot, that for a century, there is only peacekeeping, patrol jobs, ritual fighting, then someone breaks the convention, and people will be shocked to experience a total war.

Otherwise, you are very right, SF writers should focus to every aspect instead of just "dogfights".

Although it can be still a problem, that if we analyze BSG for example, people liked admiral Adama, the president, the engineer, etc, but there were also demand for a younger warrior/pilot type, Starbuck.
Again i dont say that only the last ones can be heroes, but replace them with compus means one less color.

Tony said...

TOM:

"I talked about writer's perspective."

Well, what I would say about that is that the writer has to divine what the readers' preferences are, because he has to sell books. But that has to be ballanced very carefully against having something interesting to say, because you don't want to cater totally to the reader. (You can, but then you're just writing another Harlequin romance or StarTrekWars novelization.)

"(Well i knew a guy, behind their back others joked that he goes to Iraq, because there, ha gets a medal for killing someone... )"

Uh-huh. Even if he did, he would have to be a total nincompoop to maintain that attitude. Also, IME people that say things like that don't know what they're talking about to begin with.

"Of course i am aware if one dont respect the ritual, there will be normal war, but it could be an interesting plot, that for a century, there is only peacekeeping, patrol jobs, ritual fighting, then someone breaks the convention, and people will be shocked to experience a total war."

Every story emerging out of WWI had that general background, except that instead of ritual warfare, there was colonial warfare.

"Otherwise, you are very right, SF writers should focus to every aspect instead of just "dogfights".

Although it can be still a problem, that if we analyze BSG for example, people liked admiral Adama, the president, the engineer, etc, but there were also demand for a younger warrior/pilot type, Starbuck.
Again i dont say that only the last ones can be heroes, but replace them with compus means one less color."


The ideal of the individual as a stand-alone hero is a very Western cultural trope. But so is Romantic novelizing. Eastern traditions tend to be interested in moralistic tales and the individual as a culture hero.

In any case, the duel as honorable combat is, I think, somewhat discredited by the context of its last real-world incarnation, the dogfight. Yes, the Western world went gaga over fighter pilots in WW1 and WW2. But sober reflection about what ends they were actually serving kind of irremediably tarnishes things. In WW1, the fighter pilot got in dogfights in while trying to prey on or protect balloon observers and photo-recon planes. In WW2 (and Vietnam) dogfights were about intercepting or protecting strikes against surface targets -- often cities full of civilians. There really wasn't any honor in any of it.

TOM said...

Well, OFF, as i could see, eastern people also like vigilant action hero types, but yeah even in an anime, we can see the colors are different, affected by old samurai traditions.
Hmm I can recall Space Battleship Yamato now. (the new movie version)

Thucydides said...

For a real spacecraft operating in deep space, the crew hab will actually be better protected than any battleship ever built or conceived.

Consider a balloon with the crewmember inside. For full protection against cosmic radiation and solar flares there needs to be a second balloon surrounding the first, and the interspace filled with a minimum of 5 metres of water. (Obviously a real spaceship would use engineering materials like steel and concrete, but you get the idea of the scale of things).

Since the crew, control electronics and life support would probably be inside a heavily protected hab or series of habs, the SCoDs will not directly damage the crew, but strip away all the systems outside the hab (including the engine, radiators, external weapons mounts and so on. Even the RBoD would need to stay focused on the crew hab for a considerable amount of time to burn through.

This suggests a warship's design might actually have the crew hab at or near the front of the ship in order to provide protection to the systems behind, any enemy weapon would need to blast through metres of radiation shielding before it gets to the soft underbelly of the ship. This is amplified if the ship has an aeroshell mounted on the nose to perform aerobrakeing manoeuvres when it reaches a planetary atmosphere. Laser mirrors or missile and torpedo tubes would need to be able to deploy "around" the rim of the crew hab.

A space warship would look like a mushroom or golf tee in profile to present the maximum shield profile to oncoming weapons fire.

Tony said...

Won't work that way, T. Solid engineering materials would experience spalling and fracturing. The spalling would destroy stuff inside the hab, while the fracturing would compromise airtight integrity.

jollyreaper said...

Both sides can't truly be right and good in a war or else they would settle things peacefully. At best you can have worthy opponents on opposite sides.

A war of defense against an opponent immune to reason is pretty much the closet you get to a noble war, or defending someone else against such a threat.

Things do get murky when you have two reasonable men with families and just enough food for a single family. Do the men kill themselves and one wife ro leave enough food for the kids or do they try to kill each other?

The kicker is when reasonable people think they're in that kind of situation and are blind to the alternatives.

I do think wars can be blundered into as a failure of human systems, the same way a company filled with smart people who mean well can blunder into failure and bankruptcy. There may be no evil intent, just tragic incompetence. In such a situation everyone is a victim.

Tony said...

jollyreaper:

"I do think wars can be blundered into as a failure of human systems, the same way a company filled with smart people who mean well can blunder into failure and bankruptcy. There may be no evil intent, just tragic incompetence. In such a situation everyone is a victim."

The tragic incompetence theory of a war is only adduced in hindsight and often extremely subjectively, in the sense of, "I would have known better than to try that!" When people are actually making a decision to go to war, they may be making a bad choice, but making war is not something that incompetents can do. It takes too much organization and political support.

jollyreaper said...

Potentially a lumpy golf tea. There's no reason to put an aero shell over the rest of the ship except for aesthetics so all the necessary bits would be lumping out wherever they need be.

But the other question I raised before, how likely would other-aspect attacks be? The running fight would leave a fleeing warship at a huge disadvantage unless the engines are such that it could thrust backwards just as easily and point the front at the enemy -- a very strong reverse gear! Engineering nightmare?

The other alternative is that there's a back shield just like the front shield and the engines are offset or something, firing around it.

In bombers it turned out that all-aspect defense wasn't as required and the two weakest points were front and back. By the jet age only the tail gun remained.

Maybe if there is an attack in passing, the engines are cut and the strongest surviving shield is rotated towards the enemy.

Locki said...

Rick said...

I think that, given politics that support sending it up at all, the reactor core could probably go up safely as one heavy lift payload. Even if you need a launch site in the middle of nowhere.

Even at the magic 1kg/kw barrier the reactor for a 500mw Laserstar is going to be 500 tonnes. Even if you are launching from Timbuctoo you'll have to convince the natives an Orion type rocket is not that bad anyway.

I've always thought the biggest limit on any PMF starship is radiating away waste heat. Even at impossible high efficiencies of 40% a 500mw reactor needs to radiate away 3 x 10(8) joules per second. For ease of calculations lets say the water is circulating fast enough so it can be magically heated from 0C to 100C every second. You'd still need to circulate 718kg of water every second through the reactor and then through your football fields of fragile radiators just to carry away its waste heat. And thats not counting all the computers, life support, drive, or even worse the lasers(!) etc etc adding to the waste heat load.

If the radiators die everyone dies. The radiator needs to be as light as possible, it needs big pumps, its needs to be huge and its carrying super high pressure water/sodium/whatever. And its dreadfully vulnerable to damage and loosing all of the coolent.

In engineering terms its a single point of catastrophic failure which has the added negatives of being very large and by necessity very exposed.

It doesn't sound like the sort of thing you really want to be lugging around if reliability is one of your key performance parameters.

It sounds like an absolutely terrible thing to be lugging around on a militarised vehicle.

Locki said...

Tony said...

The ideal of the individual as a stand-alone hero is a very Western cultural trope. But so is Romantic novelizing. Eastern traditions tend to be interested in moralistic tales and the individual as a culture hero.

In any case, the duel as honorable combat is, I think, somewhat discredited by the context of its last real-world incarnation, the dogfight. Yes, the Western world went gaga over fighter pilots in WW1 and WW2. But sober reflection about what ends they were actually serving kind of irremediably tarnishes things. In WW1, the fighter pilot got in dogfights in while trying to prey on or protect balloon observers and photo-recon planes. In WW2 (and Vietnam) dogfights were about intercepting or protecting strikes against surface targets -- often cities full of civilians. There really wasn't any honor in any of it.


=====================

Or to cite a more recent example The Falklands War. Popular opinion is the relatively slow Sea Harriers used their VIFFING, super training and maneouverability to destroy the much faster supersonic Mirages for 20+ kills with no losses.in air-to-air combat. The reality was not one of the Argentinians even knew they were under attack before the sidwinder blew them out of the air.

Even in WWI the Red Baron and other aces were famous for seeking out and preying on the novice pilots.

Its why the Americans are using so many drones even today. Its not even remotely fair for the illiterate tribesmen who can't shoot back but it means more of your young men and women come home.

The idea of war is to win not to engage in a fair fight. Make the other bastard die for his country and all that.

I think its arguable the idea of having a professional military which then cleanly engages the other nations professional military in a decisive engagement/war to resolve a dispute is a western tradition.

More anecdotes. I had a asian mate who lived in a suburb with a lot of Vietnamese migrants/refugees. This guy was one of the most skillful fighter I have met. Fit and strong. Boxing, Kickboxing, Karate and submission wrestling back before UFC was all the rage. A good all round fighter. Yet he'd tell that when it came to a real fight he couldn't understand why White People insisted on fighting one on one to prove a point. If its a real fight he wasn't going to show up alone, he just wanted to win. He'd bring all of his friends/cousins/relatives/neighbours etc and just make sure they'd win.

jollyreaper said...

Real fighting vs story fights:

Yeah, if you find yourself in a fair fight you're doing something wrong. The guy who starts the fight has the option to not even go there if the opposition looks stronger than him.

Bruce Lee may have had skills but for personal defense he carried a gun. He wasn't trying to prove anything, he wanted serious defense when he had no idea what an attacker might try and his reputation meant people could come after him to prove something.

I think the idea of one-on-one fights is cultural baggage from religion and chivalry like the idea of trial by combat, god deciding the victor.

We like the idea of beauty = good and right = victory. Good will win because evil is stinky. These ideas continue to be promulgated in our popular culture and are hard to stamp out. The only cultural reaction to that is grimdark crapack stories where hope is doomed.

It's hard to write a pragmatic and moral character without falling into cliches. Fighting to win including taking the cheap shot easily devolves into sociopathic anti-hero crap with the 24 guy torturing mooks for info.

Thucydides said...

The idea of a stand up fight, shock battle and resolutionon the battlefield are very distinctly Western cultural tropes. Victor Davis Hansen suggests these were developed in Classical Greece and we are carrying that as part of our cultural inheritance.

Space is actually a great place for these tropes, since it is very hard to stage ambushes, use hit and run tactics and other guerrilla war tactics. Even so called 4GW, which seeks to attack the will of the enemy population and decision makers through every available channel will be difficult to pull off in a PMF setting in space (although any ground installation and off duty service members and their families will most certainly be at risk).

WRT power reactors, there are a lot of considerations that will push R&D towards unconventional solutions. Non Carnot cycle energy extraction systems, vapour core reactors, "dusty plasma" reactors, power beaming and even aneutronic fusion will be heavily investigated in order to develop very compact and lightweight systems. Things with fewer moving parts, higher efficiencies, smaller radiators or high power/weight ratios will be in great demand, and lots of resources will be expended to try to pull the rabbit out of the hat.

Locki said...

Thucydides said...

The idea of a stand up fight, shock battle and resolutionon the battlefield are very distinctly Western cultural tropes. Victor Davis Hansen suggests these were developed in Classical Greece and we are carrying that as part of our cultural inheritance.

We're closing in on that 1000 post mark ...

But I agree wholeheartedly. Virtually every military history book I have ever read begins with a discussion of the Iliad when analysing the western way of war.

Which could be an interesting comment on western story telling itself. The oldest story in our culture is a war story and has influenced our way of war for (?) 4000 years.

Maybe Rick shouldn't feel too bad his most popular Rocketpunk topics are always about Battles in Spaaaace!

Afterall the most memorable stories have been about war for over 4000 years.

TOM said...

Well, what can be tactic and strategy in space, to make a captain a more interesting character?

Ok, gravity wells are good things.

Otherwise i think mainly about priorization, what to attack at first, second, with how much power.

Maybe decisions, whether a fighter should duck into atmosphere against KKV, should it try to protect its squadron mate, enter into a dogfight with point range cannons, maybe if the situation is really bad, expend some as missiles.

Tony said...

I think Victor Davis Hanson and his accolytes have wa-a-ay oversold the "Western Way of War" trope. Certainly the Chinese have always been aware of and have engaged in decisive stand up battle. The Japanese and Koreans fought that way as well. As did the various Muslim Conquest armies. Rather than a "Western" way of war, it's more a civilized way of war.

TOM said...

Western Way of War" trope...

West won because they had the big guns...
Although an over regulated society with supressed individualism can hinder development.

Tony said...

TOM:

"West won because they had the big guns...
Although an over regulated society with supressed individualism can hinder development."


If the West "won" anything, it was by default. There were no real competitors during the critical 500 years just gone by. Even Islam was more of a fringe problem, which was adequately dealt with by the Austrians, Italians, and Spanish, mostly out of their own resources.

Thucydides said...

To follow the Hansonite argument further, the West had the "big guns" because Western culture was ultimately more flexible and innovative, and allowed people the opportunities to innovate and prosper or fail because of these innovations. Other cultures simply could not innovate fast enough to keep up.

The point about "shock action" is not properly understood IMO; no one should doubt that almost every culture indulged in stand up battles but Hanson's point is that Western cultures seek the ultimate decision in decisive battle; the victor walks away with the laurels and the defeated slink home and accept the outcome.

Even this is a radical overstatement, the defeated usually go home, lick their wounds and plot to achieve vengeance "next time" even in the West; this is one of VDH's weaker arguments.

WRT space warfare, while it is technically very complex and only a sophisticated society could afford to indulge in it, the rather simplified setting, lack of stealth, limited force to space ratios and long timelines really make it analogous to sea warfare in the age of sail, and could be considered "2GW" (war of attrition) or "3GW" (war of manoeuvre). This is probably why it is a very popular trope in literature and film, it is relatively easy to understand and the dynamics are familiar for most audiences, immersed as they are in countless war movies, books and video games.

If space war had analogues to roadside IED's, suicide bombers, Al Jezzera, children throwing rocks at tanks, the Al Qaeda network and so on, it would be much messier and more difficult to depict, and it would also be much more ambiguous in character.

jollyreaper said...


If space war had analogues to roadside IED's, suicide bombers, Al Jezzera, children throwing rocks at tanks, the Al Qaeda network and so on, it would be much messier and more difficult to depict, and it would also be much more ambiguous in character.


So in the inhabited solar system you have Earthsphere, the Jovian Cooperative, and the Saturnian Soviet all with RKV's pointed at each other with Armageddon the result of open hostilities and so the real fighting happens in the belter colonies where a war of assassins is carried out between secret agents, cloak and vibro-dagger spy games.

That's certainly another possibility.

TOM said...

"so the real fighting happens in the belter colonies where a war of assassins is carried out between secret agents, cloak and vibro-dagger spy games. "

Yeah i also think so, that can be the room of "warrior" type individual characters.

Anything could add something to my list about possible tactics and strategy in space?
A captain needs to bring hard and significant decisions to make him interesting.

Tony said...

Thucydides:

"To follow the Hansonite argument further, the West had the 'big guns' because Western culture was ultimately more flexible and innovative, and allowed people the opportunities to innovate and prosper or fail because of these innovations. Other cultures simply could not innovate fast enough to keep up."

I know a lot of people don't want to hear this, but the biggest factor may in fact have been Christianity, from which we get the concepts of individual worth and a rational universe. With those as philosophical starting points, it's hard not to be competitive and innovative over the long run.

"The point about 'shock action' is not properly understood IMO; no one should doubt that almost every culture indulged in stand up battles but Hanson's point is that Western cultures seek the ultimate decision in decisive battle; the victor walks away with the laurels and the defeated slink home and accept the outcome."

Actually, decisive battle in the form of settling arguments but leaving both parties independent is indeed western. But it's a voluntary constraint. In Eastern warfare, and in the the West vs East, or West vs "barbarians" (in quotes because that word can be very subjectively defined), the objective is dominance and/or conquest.

"Even this is a radical overstatement, the defeated usually go home, lick their wounds and plot to achieve vengeance 'next time' even in the West; this is one of VDH's weaker arguments."

See above -- limited, intra-communal war may in fact be the key contribution of the West, not decisive war.

"WRT space warfare, while it is technically very complex and only a sophisticated society could afford to indulge in it, the rather simplified setting, lack of stealth, limited force to space ratios and long timelines really make it analogous to sea warfare in the age of sail, and could be considered '2GW' (war of attrition) or '3GW' (war of manoeuvre). This is probably why it is a very popular trope in literature and film, it is relatively easy to understand and the dynamics are familiar for most audiences, immersed as they are in countless war movies, books and video games."

Making a distinction between maneuver and attrition is glaring error to begin with. The whole point of maneuver is not to avoid attrition, but to gain an advantage in applying attrition. Unlimited maneuver with little decisive fighting is the consequence of very low force to space ratios, while purely attritional warfare along defined fronts (WW1 Western Front) or within defined zones (WW1 && WW2 submarine and aerial warfare) is the result of way too much force to space.

IMO in space, in the pmf, one would find a lot of maneuver, in the form of jockeying for position, punctuated by high rates of attrition over very short timespans, when one side or the other perceives and advantage and attacks.

"If space war had analogues to roadside IED's, suicide bombers, Al Jezzera, children throwing rocks at tanks, the Al Qaeda network and so on, it would be much messier and more difficult to depict, and it would also be much more ambiguous in character."

I think that's something one would see in long periods of "peacetime", because nobody wants to fight a shotguns across the dining table war very often.

Locki said...

Tony said...

I know a lot of people don't want to hear this, but the biggest factor may in fact have been Christianity, from which we get the concepts of individual worth and a rational universe. With those as philosophical starting points, it's hard not to be competitive and innovative over the long run.

=============

I'm a firm agnostic leaning towards the atheist but you'd be pretty silly to ignore Christianity's key role in the development of western society.

In fact many of the big conflicts would be a lot less adversarial if the Dawkin-ish atheist acknowledge the debt the West-liberal societies owe to Christianity - a religion which emphasises the individual.



Making a distinction between maneuver and attrition is glaring error to begin with. The whole point of maneuver is not to avoid attrition, but to gain an advantage in applying attrition. Unlimited maneuver with little decisive fighting is the consequence of very low force to space ratios, while purely attritional warfare along defined fronts (WW1 Western Front) or within defined zones (WW1 && WW2 submarine and aerial warfare) is the result of way too much force to space.

=====================

I'm leaving myself wayyyyy open to accusations of pedantic hair splitting here but my readings of the definitions of maneuver warfare vs attrition warfare are subtly but significant different to your's Tony.

Attrition warfare is not simply throwing more men at the trenches until the other side gets ground down.

Maneuvering to bring greater force/weight/shock to bear and blow a hole throught the line (eg Ulysseus Grant's get the most men there the first-est) is attrition warfare. The point of maneuvering is to apply a superior amount of force.

Maneuver warfare's aim is to get inside the decision tree of the opponent and make them feel off balance and like they have lost the initiative through the use of maneuver. Now obviously you have to have enough force to blow shi* up when you get there and not just dance around like an agile fairy but the aim of the maneuvering becomes the end in itself.

I've got an old dusty cold war summary handbook at home and I'll post the definitions here in a few hours. It was a big transition the US army went through from the late 70s (attrition warfare) to maneuver warfare in the mid 80s and the definitions are wonderfully concise and elegent.

Locki said...

TOM said...

Well, what can be tactic and strategy in space, to make a captain a more interesting character?

===============

There's a great 3 paragraphs in Arthur C Clarke's 2010 where the Russian-American crew in the Alexei Leonov are considering firing their communications laser at the Chinese Tsien to stop them illegally inspecting the Discovery 1 and ransacking all of its information about the Monolith.

They then dismiss the possibility as impractical, unethical etc etc. Those few paragraphs were probably more suspensful than the entire Star Wars war against the evil empire (TM).

If you are writing trully hard SF with interesting characters I've always thought this was the better model.

The drama and suspense and technical challenge is around the actual voyage to Jupiter (A Space Odysey style) and there may be a few incidental episodes of violence along the voyage.

Designing a ship purely for violence seems to be be mostly magitect/handwavium given near future levels of technology.

You virtually need handwavium just to get enough delta-V, radiation protection, life support tetc to get a human safely to Jupiter and back. To transport humans AND haul around enough firepower to level the eastern seaboard AND carry enough defences to stay in the fight will take at least an order of magnitude jump in our technology. IMHO it probably also requires some of the fundamental things we believe about physics to be wrong. The universe's natural laws don't seem to want us to zip around blasting evil do-ers with derring do.

TOM said...

"I know a lot of people don't want to hear this, but the biggest factor may in fact have been Christianity, from which we get the concepts of individual worth and a rational universe. With those as philosophical starting points, it's hard not to be competitive and innovative over the long run. "

Tony : im not the religious type, but i certainly dont mind such sentences. :)
I would also note the good enviromental factors, for example American natives lacked the horse, the cow, corn require more work than wheat...


Otherwise i wondered, that space warfare could be like to a game of chess, you can see every movement of the enemy, but there are still strategy.
In this crude analogy, the mothership is the queen /tender and logistic ship for your fleet, mobile operation base for frigates, it can occupy colonies, it can secure them by deploying its parasites, unloaded, it can outrun battlecruisers/.
Battlecruisers are bastions, cruisers are runners, frigates are houssars, fighters are footmen.


"There's a great 3 paragraphs in Arthur C Clarke's 2010"

Interesting :), although i didnt really liked the Space_Odyssey film.
But yeah, i guess, instead of old cliches, hard SF should focus on heavy decision making and things like that in space.

Thucydides said...

The Christian component of Western civilization is indeed a key part of our cultural inheritance, and we ignore or dispose of it at our peril. To pull another book out of the library; Niall Ferguson suggests that other civilizations have deciphered the “Killer Apps” of Western civilization, and now we are at risk of being overtaken.

Since *we* created the "killer apps", it seems more likely that other civilizations have learned to copy the “killer apps” but will still be behind the curve in terms of finding new applications and updating them. Our cultural inheritance of individualism and free markets not only promotes the development of civilizational “killer apps”, but also the efficient use of them.

WRT the distinction between attrition warfare and manoeuvre warfare, the general “rule” is that the decisive action in 2GW is predicted on the destruction of enemy forces while the decisive action in 3GW is predicted on collapsing the enemy’s military will by attacking his weak points faster than he can counter and reconstitute. There are elements of manoeuvre in 2GW (massing forces for the decisive battle) and attrition in 3GW (moving in for the kill before the enemy knows you are there).

WRT Locki’s point, a spaceship moving at interplanetary speeds is a pretty potent weapon all by itself (simply releasing the shuttle at that speed on an intersecting orbit is the equivalent of dropping a JDAM or firing a missile), so if someone suddenly decides to engage in PMF space war, they don’t have to go very far. Similarly, if laser thermal power becomes the main method of launching and manoeuvring spacecraft, then the technical and economic basis of laser weaponry has been established.

TOM said...

"Since *we* created the "killer apps", it seems more likely that other civilizations have learned to copy the “killer apps” but will still be behind the curve in terms of finding new applications and updating them. Our cultural inheritance of individualism and free markets not only promotes the development of civilizational “killer apps”, but also the efficient use of them. "

That is a possibility, although i would note, now every society aware about the power of invention, that they has to become nuclear and space power, coupled with their traditional ability to organise monumental buildings... China's space program less likely to be hindered by politicans only care about short term goals, reelection.

Yeah lasers can be more useful in PDF, better waste heat treatment and power supply.
Although laser-aiding rockets to orbit only requires short-range IR lasers, or possibly microwave generators, microwaves scatter more, but generating them also more efficient.

Tony said...

WRT "Maneuver Warfare" -- in quotes, capitalized -- I think it's important to understand that it's a brand, not a real thing. All war involves maneuver and attrition. "Maneuver Warfare" is just a theortetical construct that claims the maneuver can always be applied, and attrition minimized as a consequence.

The problem is that it's intellectually dishonest. No, maneuver could not be applied on the Western Front in WW1, because the force-to-space ratio was too high, and there was nothing anybody was going to do to change it. All of the maneuver that both Napoleon and Wellington did was designed to force the enemy into an unfavorable position for the attritional struggle of battle. All Mongolian maneuver had one aim -- to put the enemy in an ufavorable posture when the final, highly attritional, attack came.

Even in the campaigns of WW2 that "Maneuver War" theorists love to quote, there was all sorts of attrition going on all of the time. That was certainly the case in North Africa, where a few days of maneuvering was punctuated by weeks of attack and counterattack, as supplies were accumulated for the next big operation. That went on for three years, almost, at huge cost in lives and resources. The great maneuver campaigns in the East in 1941-42 devloved into hyper-attritional stuggles aroung Moscow and within Stalingrad. (The latter at times referred to as "Verdun on the Volga".) The great operational maneuver in 1940 in france was bought at the cost of heavy attrition during the Meuse crossing operations, and among the units sent into Holland and Belgium to distract Allied attention.

In fact, maybe the truest thing ever said about maneuver -- either by William DePuy or Don Starry, I can't remember which -- was that it is, in reality a benefit of attrition. That means that you get to maneuver once you have fought your way free of enemy encumbrances. YOu don't get to maneuver simply because you want to. I think pretty much all of military history bears that out.

Rick said...

I'm at least a little bit skeptical of single-factor explanations for the industrial revolution and the West's military advantages. Especially when they come wrapped in a neat ideological package.

I suspect it was a variety of factors, plus some plain good luck.

For example, the Amsterdam-London intensive commercial region happened to use coal as 'firewood,' making the Newcomen steam engine a practical tool, worth developing and improving on. Compare to Hero of Alexandria's aeolipile, which had only gimmick uses and so inspired no further development.

Christianity has certainly had an enormous impact - or, really, multiple enormous impacts, working in various directions. But I'm not sure that it stresses the dignity of the individual believer more than Islam does; Islam stresses it very heavily indeed.

Something I would call attention to is mainstream orthodox Christianity's rejection of gnosticism, and the corollary celebration of the physical universe as God's handiwork, not a fraud perpetrated by a demiurge.


Otherwise i wondered, that space warfare could be like to a game of chess, you can see every movement of the enemy, but there are still strategy.

+ 10

A very good point that I am guilty of forgetting.

The adage that amateurs study tactics, professionals study logistics, could be even more true in space, especially PMF space, than in other domains.

I see a pervasive tendency in these discussions to overestimate delta v and mission flexibility. As noted before, space operations 'run on rails.' Once you make a substantial orbit change, you are committed to it.

This could make the distinction between 'maneuver' and 'attrition' a delicate one indeed. The main purpose of weapon fire, kinetics or zaps, may not be to inflict damage, but to use the threat of (hammer on eggshell!) damage to force the enemy to burn *very* precious delta v.

TOM said...

I wonder on the usage of magsails (maybe pushed by particle beams), the low acc. makes them unable for "tactical" use, but can have a strategic use the change orbit, so your fleets can threat more targets.

Locki said...

Re: Tony's analysis on Maneuver warfare

I'll admit to being the very worst kind of armchair general but your analysis seems to make sense from a common sense point of view. I did think some of the discussion on the aim of maneuver warfare smells of sophistry and even worse some political correctness to cover up the fact your armies are killing people and blowing shi* up.

History seems to indicate maneuver warfare only becomes possible or even desirable where one side enjoys a significant qualititate edge (and quantitative disadvantage). Re: Mongols, Germans early WWII etc etc.

Its a way of thinking to try to stop your small but elite army getting ground down by a lesser foe.

Where quality is similar you are better off using the time honoured KISS (keep it simple) and grinding them down. See the USN battleplan at Midway vs Yamamoto's elaborate double ruse. Hell the entire allied campaign was essentially grinding down the japanese and germans.


Tom said:
Interesting :), although i didnt really liked the Space_Odyssey film.
But yeah, i guess, instead of old cliches, hard SF should focus on heavy decision making and things like that in space.


===============

The book was vastly superior to the movie (a strict 2.5 star out 5 effort) and is IMHO one of Clarke's best, most imaginative works.

Clarke's was terrible at characterisation but some of his ideas were fascinating. AFAIK it was one of the very first to discuss life in the complex atmospheres of Jupiter and the oceans of Europa. They are the two most memorable visually and emotionally evocative chapters but were cut for the movie. "There is life on Europa, I repeat there is life on Europa ..."

Locki said...

Rick said ...

I see a pervasive tendency in these discussions to overestimate delta v and mission flexibility. As noted before, space operations 'run on rails.' Once you make a substantial orbit change, you are committed to it.

Me too. Just to get enough delta-V to safely haul a couple of human's to Jupiter/Saturn and back in a timeframe where zero-G and cosmic rays don't do irreparable harm to your astronauts practically uses up all of your free magitech passes by the time you have finished your introduction.

2010 was one of the very first novels I ever read so it influences me disproportionally. But even with its setting featuring near impossible tech like its Sakharov drives and 200m long nuclear thermal rockets and centrifuge artificial-G habitats (Discovery)felt the need to also include suspended animation as one of the main plot points. The delta-V on the twin nuclear bad boys (Discovery and Alexei Leonov)is so crappy 80% of the crew is put to handwavium sleep just so there's enough supplies for them at the end of their 2yr one way journey.

And suspended animation just isn't going to work given are advanving knowledge in medical science.

Tony said...

Locki:

"History seems to indicate maneuver warfare only becomes possible or even desirable where one side enjoys a significant qualititate edge (and quantitative disadvantage). Re: Mongols, Germans early WWII etc etc.

Its a way of thinking to try to stop your small but elite army getting ground down by a lesser foe."


Except that the Mongol armiesoften outnumbered their enemies in numbers of armed men, even if as a society they were realtively low in population. Their idea of logistics was to overwhelm the enemy then subsist on his stuff.

Also, being numerically and materially superior doesn't preclude maneuver, if the opportunity presents itself. Look at the operations of the Western Allies in August, 1944, once they had broken out of their beachhead. Or, even after blasting the Iraqis into smithereens with six weeks of air attacks, the Coalition forces still maneuvered around them in 1991, rather than simply push them out of Kuwait. Or Grant, during the Vicksburg campaign, having a numerically superior army, but a rotten operational situation, abandoning his logistics base and maneuvering into the enemy rear in order to break up a strategic stalemate.

Maneuver is something you do when you can or you have to -- provided, of course, you can shake yourself free of enemy interference.

"Hell the entire allied campaign was essentially grinding down the japanese and germans."

In the history of WW2, there were levels at wich the same campaign can be both maneuver and attrition. Both the strategic air and submarine campaigns were ruthlessly attritional at the strategic level. But operations were often designed to maneuver both forces and technologies to achieve surprise, both strategic (technological advances) and tactical. And tactical combat in the air and at sea was and is all about maneuvering firepower into an advantageous position before shooting.

The previously mentioned campaign in North Africa, on the other hand, was ruthlessly attritional at the tactical level -- on the open desert, when you got in range of the enemy, your options were to shoot it out, shoot it out, and...shoot it out. Also, maneuvering within sight of the enemy was an invitation to artillery shelling with as many guns as were in range. Operationally, on the other hand, the armies were constantly trying to maneuver around each other. But strategically, it was all about shovelling men and equipment into the furnace until one side was worn out.

The same strategic approach was used in the Solomons campaign in the second half of 1942. Men, planes, and ships were fed into the battle (described as "Neptune's Inferno" in the title of Eric Hammel's book) as they became available, until the US forces proved they could out-suffer the Japanese.

The long and the short of it is that, in modern industrial warfare, maneuver and attrition often appear, disappear, and change places, depending on the phase of the battle and one's level of percption or interest.

Anonymous said...

OK, I'm back from vacation and have spent hours going through the new posts.
1.) While it may be possible to use common components for both a plasma drive and a particle beam weapon, I still think that they would be seperate systems for effectiveness.

2.) Manuover/dodging/escape...you might design a ship that had two propulsion systems (a high-ISP/low thrust and a low-ISP/High thrust); however, it would have to sacrifice something major(firepower, armor,shielding, sensors, or C&C),and have a very specific mission, like KineticStar-Killer; however, it wouldn't have much use outside of that one mission.
3.) All the manuover and attrition would take place in the battle zone (probably in orbit), but getting your combat force from one orbit to another would be logistics. Most people put in charge of planing, say for a couple of examples; putting down a revolt on Titan, or invading an enemy country's colony on Europa, would look at the capablities of the targets, their own capabilities and limitations, and the objectives of the operations. On Europa, you'd need troop landers, transports with lots of hab capasity, ships that can support ground troops, and a blocking/protective force for that large group of ships; for Titan, you'd need all the above, but also Titan-capable aircraft, maybe light armor, some artilliery, and a LOT more C&C/sensors/communications and EW. In both cases, the planner must take into account how much distruction and/or civilian deaths to be avoided (or tolarated). Oh, and if you're not 100% sure what those colonies have in the way of combat capabilities, you need to add in some sort of "anti-surprise" capabilities.

Lastly, for now; a military high endurance spacecraft would need a lot of power and the ability to mount various modules for different missions. I can see combat spacecraft being rated by size and endurance, rather than by specific mission or role (except for like that example I used earlier), or even by the type of weapons it mounts; alternately, I can also see some nation or colonial organization going the other way and classifing combat spaceships by weapon types or mission or role.

Ferrell

jollyreaper said...

Cryosleep probably won't happen but we have one hibernating primate and scientists believe they can induce it in humans. The primary purpose at the moment WLAN be stabilization for surgery.

A secondary use would be space emergencies. (looking ahead a bit, I know.) Low on air? Our surplus personnel in hibernation and you might just stretch your supplies. Evacuating a station with insufficient numbers is transports? Hibernation allows you to double-stack for short periods.

Locki said...

Geez. I just read back through the last few posts and realised how I old I sound when I talk about a novel titled "2010" as a science fiction book. Time goes too fast.

A couple of quick points. I got a mate who just finished up staff college but I still have trouble wrapping my head around the concepts. Here's a couple of definitions as promised earlier:

1. Definition of Manoeuvre pre-1980 = "forces are manoueuvted to gain an advantage over the enemy, to close with him and destroy him>"

2. Definition Manouevere post 3GW = "is the dynamic elemnt of combat, the means of concentrating forces in critical areas to gain and to use the advantages of surprise, psychological shock, position and momentum which enable smaller forces to defeat larger ones."

3. Closing speed of KKVs
- I finally got around to doing a couple of quick sums in my head. The closing speed of a bog standard chemical missile is going to be really really fast.If I were to haul one of today's SM-3 missiles into orbit its closing speed would be astronomical in a vacuum. That missile can attain Mach 4-5 (1-2km/sec)in an atmosphere (eg drag) and sustain that speed for minutes for about 500km range. In a vacuum if it expended all of that energy just accellerating (no drag) it'll hit .... god only knows what speed. 100+ km/sec ??? Why are we even talking about lasers? Ditto armour or any sort of passive defence. Even a dinky 15kg Stinger missile will hit you at 4-8km/sec.

This makes relatively short ranged particle beams with a range of 10-30km utterly useless even for point defence. Even today the supersonic Sunburn missile with a mere closing speed of 1km/sec has rendered the old 20mm Phalanx obsolete. Even if you do hit the missile at max 1.5km range the flaming wreckage will still impact your ship, kill your radars and electronics and mission kill your warship. The USN has completely replaced Phalanx with the much longer ranged Sea Ram.

If missiles are closing in that fast you are going to want to shoot them down well ahead of time.

TOM said...

Locki : maybe i'm terribly wrong, but i think, air pressure isnt only hinder acc. but can also help it, bigger pressure at the end of thrusters.
Also there are much bigger distances in space, missiles have to provide big delta-V, they will need MUCH more fuel.
Although with shield like projectiles, defence against them might be also easier.
I still think, it might be not that bad idea to dodge at least the main missile bus, after it mission killed, so you only have to endure the shrapnels of smaller warheads.

Locki said...

TOM said...

Locki : maybe i'm terribly wrong, but i think, air pressure isnt only hinder acc. but can also help it, bigger pressure at the end of thrusters.

Now I'm an even less worse rocket scientist than I am theoretical sub-atomic particle physicist but anecdotally ...

One of the big engineering issues with air-breathing scramjets is that they are more efficient at low altitude (air thicker for the scramjet) but rapidly drop off in efficiency as the air thins at high altitude.

Conventional rockets on the other hand are inefficient at atmospheric pressures but rapidly gain in efficiency as you get higher and the air thins. At a certain height the conventional rocket exceeds the efficiency of the air-breathing scramjet - even though it has to lug around its own oxidiser.

I read an analysis wayyyyyy back on rec.arts.sf.science (am I the oldest guy here except for Rick?) which basically pointed to scramjets never being a viable single stage to orbit solution because of its inherent inefficiency at high altitudes.

One of the engineering types may correct me (Phil? Byron? Tony?) but I think chemical rockets work even better in a vacuum.

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