tag:blogger.com,1999:blog-7494544263897150929.post7487475649173539558..comments2024-03-28T00:36:19.403-07:00Comments on Rocketpunk Manifesto: Tough Guide: ElevatorsRickhttp://www.blogger.com/profile/16932015378213238346noreply@blogger.comBlogger43125tag:blogger.com,1999:blog-7494544263897150929.post-12758516410798814452011-04-23T09:57:13.339-07:002011-04-23T09:57:13.339-07:00If say the external structure starts breaking up, ...<i>If say the external structure starts breaking up, you apply the brakes, slowing the flywheel, spinning the struture until is stays in orbit</i><br /><br />I think failure would propagate much faster than you could spin the thing up!<br /><br />And this seems to require non-orbiting bridge span structures up to thousands of km long!<br /><br />All in all this seems at least as technically demanding as a conventional elevator, plus all sorts of spectacular failure modes. :-(Rickhttps://www.blogger.com/profile/16932015378213238346noreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-51187826545449195762011-04-23T01:20:41.928-07:002011-04-23T01:20:41.928-07:00Here's a concept for a space elevator, an orbi...Here's a concept for a space elevator, an orbital ring.<br /><br />We set 12 or more even number of stations into space, in a stable low orbit. They are then attached by wires to form a ring, with little tension in the wires. We then start constructing the giant flywheel. It is seembled in curved sections, starting from one orbiting station to another, and doing so symetrically. The first layer is simply a tube made of struts. The second is an assembly of electric motors, pulleys, wheels and water tanks that can be pumped full or empty between each other (make them extensible bladders). Finally comes the flywheel itself. It as a ring of carbon encircling the whole of the station's orbit. It is spun up to orbital velocity, matching with the structure surrounding it. Then, it is spun up faster, and the surrounding structure is slowed down to zero relative to the ground. They compensate for each other, and the ring's strength absorbs irregularities, centifugal force does the rest. Depending on the strength needed, carbon may not be necessary, and a cheper filler can be added. <br />The external structure is then attached by guy wires to the ground, followed space elevators. The elevator cars pull on the structure, the main electric engine provinding the lifting force is on the ground, but it runs a loop over one of the aforementioned station. To balance this force (and avoid catastrophic oscillations in the ring) water is pumped to the opposite end. If this is not enough, I'm sure the guy wires can be reinforced to support extra loads. <br /><br />The advatanges of this system is that<br />a)it is in low orbit so accessible and easy to reach for maintenance and such<br />b)it only requires short lengths of supermaterial, if at all<br />c) we can start building one tomorrow, no passing asteroid required<br />d)no chance of catastropic failure or it falling to the ground. If say the external structure starts breaking up, you apply the brakes, slowing the flywheel, spinning the struture until is stays in orbit<br />e)the only exposed parts are still relative to the ground, meaning you can go straight up or down<br />f)oscillations are easily counteracted by pumping water throught the pipes, and if all fails, you open all valves and let everything die down <br /><br />Disadvantages include maintaining balance every part of the way, and the wear and tear of a fast spinning, massive flywheel with corresponding moving parts. <br /><br />Comments?KraKonhttps://www.blogger.com/profile/16247562094101986439noreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-17623200021981557872010-12-29T07:47:20.090-08:002010-12-29T07:47:20.090-08:00That's one way to get back down! But I would g...That's one way to get back down! But I would guess that by the time we have the tech and traffic demand for elevators, there will be alternate ways of rescuing stuck cars.Rickhttps://www.blogger.com/profile/16932015378213238346noreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-57389514849374203592010-12-22T16:23:53.981-08:002010-12-22T16:23:53.981-08:00One possibility for rescue is to make each car als...One possibility for rescue is to make each car also a reentry capsule. Aerobraking is probably cheaper than inching the cargo down, and if there are people aboard when a car gets stuck, all it has to do is release whatever is holding it to the cable (and probably fire maneuvering rockets to get to a safe distance).Danielhttps://www.blogger.com/profile/03150243938040644775noreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-2845421221907898212009-07-30T20:44:58.504-07:002009-07-30T20:44:58.504-07:00But you don't hoist the cable, you hoist the c...But you don't hoist the cable, you hoist the counterweight. The counterweight, being beyond geosync, has lifting power which transmits through the cable to the car. The cable itself ends up being neutrally buoyant. <br /><br />But like you said, this all hinges on the ability to make full strength cables of the appropriate lengths.Citizen Joenoreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-30181793840265435402009-07-30T16:02:52.468-07:002009-07-30T16:02:52.468-07:00I was sort of thinking of getting power the same w...I was sort of thinking of getting power the same way electric trains do - but as you say, 40,000 km is a lot of transmission line.<br /><br />On the other hand, keeping a hoisting cable aligned over 40,000 km is also a challenge! I also have a vague feeling that the hoisting cable would weigh much more than the trains, meaning you'd be using most of your power just to move the cable.<br /><br />But anyway, all this is assuming we're able to make long cables with the full strength of carbon nanotubes. Currently (I was reading this in my day job) they spin nanotube fibers into 'yarn,' which - currently - has only 10 percent of the strength of the individual tubes.Rickhttps://www.blogger.com/profile/16932015378213238346noreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-63644662601572166472009-07-30T05:07:56.999-07:002009-07-30T05:07:56.999-07:00The typical idea of the elevator is stationary tra...The typical idea of the elevator is stationary track with moving cars. Actual (building type) elevators use spools and/or counterweights with emergency brakes to grab the guide tracks. If you're using 'crawlers' to climb a stationary cable, they put wear and tear on the cable with every accent/descent. 'Beaming' energy 40,000 km through the atmosphere isn't really feasible either. Transmitting power through the cable has problems as well, line degradation, heat dissipation, etc. and you still need a big honkin' motor to lift your payload. <br /><br />The advantage to the spooling system is that the very large wheel used for the spools is more gradual and thus less damaging to the cable. Since the cable is moving by a stationary point, it can be inspected for damage and repaired as needed. There is no need for a large motor on the cars, since they just hook on to the cable and get pulled up/down. Even the lift motor isn't really needed since it relies on centripetal force. Additionally, the mass for any motors/reactors/power supplies is where it is needed, at the counterweight. With the counterweight extended, it could also produce artificial gravity for those living there. It could be an acclimatizing site. So go all the way up to the counterweight, where gravity is half or less of Earth. When you get used to low gravity (and even varying gravity as the counterweight does its work) you can then move the the GeoSync station and eventually off in space ships.<br /><br />Tangling is a big problem though.Citizen Joenoreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-71999477307104705392009-07-29T18:30:25.666-07:002009-07-29T18:30:25.666-07:00"The toughest rescue problem arises if someth..."The toughest rescue problem arises if something immobilizes a train - a broken wheel, or damage to the track structure (as distinct from the primary strength cable it is attached to). Then you'd have to bring a train on the other track to transfer passengers.<br /><br />This also rules out a simple funicular style system with a car/train on each end of the moving cable. In that system (which is what I thought you had in mind) if one train is immobilized, so is the other. But you speak of spooling up cables, implying that each track runs independently. But I'd be very worried about tangling/jamming with any cable-hauled system!"<br /><br />Wait: doesn't the concept of the Space Elevator is that the cable doesn't move; the cars do. They are either powered by external beamed energy from the ground to the car, or they are powered by a current comming through the cable itself. If a cable is damaged, it may be repaired by 'reweaving' it; if it is broken, then you have to re-string it; the lower part would fall to the ground and the upper part would be drawn up into higher orbit.<br /><br />FerrellAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-89021011415663479612009-07-29T08:22:31.350-07:002009-07-29T08:22:31.350-07:00The toughest rescue problem arises if something im...The toughest rescue problem arises if something immobilizes a train - a broken wheel, or damage to the track structure (as distinct from the primary strength cable it is attached to). Then you'd have to bring a train on the other track to transfer passengers.<br /><br />This also rules out a simple funicular style system with a car/train on each end of the moving cable. In that system (which is what I thought you had in mind) if one train is immobilized, so is the other. But you speak of spooling up cables, implying that each track runs independently. But I'd be very worried about tangling/jamming with any cable-hauled system!Rickhttps://www.blogger.com/profile/16932015378213238346noreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-29930704779161422162009-07-28T10:32:52.243-07:002009-07-28T10:32:52.243-07:00I was thinking multiple km diameter pulleys or spo...I was thinking multiple km diameter pulleys or spools rather. They WOULD have to coil up about 40Kkm of cable. <br /><br />A rescue mechanism for a passenger car could simply be releasing the brake/clamp and letting gravity pull you down the cable to 'safety'. That trip could take weeks though.<br /><br />Multiple tracks/cables could use the same guide tether, but there's issues with the lines tangling. <br /><br />Additionally, since the cables that support the payloads are moving, they can be continually inspected as they pass the various stations. If needed, they can be repaired at the stations as well.Citizen Joenoreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-52022303748007775202009-07-28T09:41:26.470-07:002009-07-28T09:41:26.470-07:00The longer cable isn't a problem, but if it is...The longer cable isn't a problem, but if it is the size of a suspension bridge cable it won't go around the pulley at the top very easily, and probably has much more mass than the trains.<br /><br />Otherwise, as to whether individual cars are powered depends on several things, including whether you're running multi-car trains. In electric railroading, the choice between locomotive hauled trains and self propelled MU cars (like a subway train) depends on lots of secondary operating considerations.<br /><br />If passengers are carried, one important consideration will be rescue from stalled trains. Along most of the line the only way to reach them is another train.Rickhttps://www.blogger.com/profile/16932015378213238346noreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-82596532730355505732009-07-28T05:34:25.881-07:002009-07-28T05:34:25.881-07:00The cars themselves don't need to be powered a...The cars themselves don't need to be powered any more than the cars of an actual railroad. So box cars may have some sort of battery operated lighting and transponders, but nothing significant. Passenger cars need life support, but the payload is the car, not really the people in that case. I suspect however, that people would be transported up by some other technique, leaving the elevator for heavy lift of material.<br /><br />Of course, I'm asking for three times the length of cable/tether. But if we assume we can make 40Kkm of cable, making three times that amount shouldn't be a problem.Citizen Joenoreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-67233311112992860132009-07-27T21:23:54.679-07:002009-07-27T21:23:54.679-07:00qwert - I agree that normal inspection and mainten...qwert - I agree that normal inspection and maintenance would be done by trains. That is how railroads do it, or used to. Repairing a damaged cable is problematic, though. I suspect you'd have to replace it, then winch the damaged one up.<br /><br />Citizen Joe - The technical term for what you describe is a funicular. (Or at least when it's inclined; I don't know if the term is used when the lift is vertical.) But I suspect that these are big, heavy cables, like suspension bridge cables, so alas the arrangement wouldn't work.<br /><br />But you might be able to use regenerative braking of descending trains to recover most of their potential energy. Though that gets into the whole question of how you power the trains, emergency braking, etc.Rickhttps://www.blogger.com/profile/16932015378213238346noreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-19747890564276706242009-07-27T18:46:27.079-07:002009-07-27T18:46:27.079-07:00I figured out a work around for the trains needing...I figured out a work around for the trains needing to have engines on them.<br /><br />Step 1: build the beanstalk with some sort of station at Geosync. This cable only needs to support itself, no weight. It is just a guide cable. <br />Step 2: build a cable three times as long where one third is spooled on the ground, and one third is spooled into the counterweight.<br />Step 3: install the heavy engines/reactors/motors in the counterweight and on the ground station. <br />Step 4: attach payload to grapple point on tow tether. <br />Step 5: counterweight starts reeling out cable allowing itself to drift further away from geosync and thus have more lift capacity. <br />Step 6: when the counterweight has enough lift to pull up the payload, it stops reeling out the cable and lets the centripetal force lift the payload and whole cable upwards. The ground station plays out cable at the same time (acting as a brake as needed). <br />Step 7: Counterweight reels in cable faster and faster as the payload leaves the atmosphere. Maybe a hundred or so km/hr in the atmosphere and then accelerating to ten times that when clear of air resistance. Probably a little under two days to reach geosync. <br /><br />What I did there was change from a railroad to the cable car system. The heavy weight of the machinery is where it is needed and helpful, meanwhile the payloads can remain light without the need for heavy motors.Citizen Joenoreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-76498979222515263592009-07-27T13:56:06.650-07:002009-07-27T13:56:06.650-07:00Maintaining a Space elevator:
I don’t think you w...Maintaining a Space elevator:<br /><br />I don’t think you would need any type of airships or space trucks, like Ian_M says, in order to maintain and repair an elevator, all you need is to have at least two separate tracks (this means, two routes along which two trains can drive simultaneously).<br /><br />Regular maintenance could be done in a similar way to how it’s done today in the offshore oil industry: Different damage control sensors built inside the cables would transmit data about the state of the track. Additional sensors (presumably those which require more space) on each train would provide additional information on every trip.<br />Periodically (every week, month, year, day?) you can send a train with technicians and more advanced equipment for a more detailed inspection.<br /><br />If a defect is found you can have two options: to repair the cable in place or to replace it. If it is possible to drive along the damaged track (a redundant cable for each track would be a help), you can put a train just in the affected area and let the technicians to repair it from inside the train. Otherwise it will have to be done from the adjacent track.<br /><br />I think however that it will be easier to replace it and repair it on ground. (is it even possible to repair a carbon nanotube cable?)<br />In order to replace a cable, for example track 1, you can use the train at track 2 to bring the cable to the ground. After that you use track 2 again to drive a second train to lay a second cable from ground to orbit, not unlike a ship which lays a deep ocean telephone cable (if that’s not possible then you use the train to supply the orbital station with enough material to bring a cable down, assisted by construction crew and equipment from the train if necessary).<br /><br />This way, the only vehicle needed to maintain the elevator in normal conditions would be the trains of the elevator itself. Additional tracks would allow to conduct maintenance operations without any need to interrupt traffic. <br />If I am correct supposing that the most difficult part of building an elevator would be to put the required structure in orbit and to send down ( I am right supposing you would build such a thing from orbit to ground, not?) the first track (for additional tracks you can assist yourself with the trains), could such a scheme work?Hhttps://www.blogger.com/profile/16142184728794858358noreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-42193112691307608812009-07-27T11:32:20.586-07:002009-07-27T11:32:20.586-07:00Ian - Yes, we could build expendable SSTOs. Signif...Ian - Yes, we could build expendable SSTOs. Significantly, the preference has been for 2-stage vehicles, to get a larger payload fraction. (The first generation US and Russian orbiters were 'one and a half stage' so that all engines could be started on the pad.<br /><br />As you note, alternative launch techs from laser launch to beanstalks try workarounds, but they all encounter some form of the challenge - in the case of beanstalks, the extreme tensile strenth required; for laser launch, the challenge of beaming the needed power though the atmosphere, and hassles of launch geometry.<br /><br /><br />Citizen Joe - <i>What if you had tow counter rotating rings around Earth with multiple pinion gears between them.</i><br /><br />My head explodes just thinking about this. :-)Rickhttps://www.blogger.com/profile/16932015378213238346noreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-21591868082927346802009-07-26T17:13:00.067-07:002009-07-26T17:13:00.067-07:00What if you had tow counter rotating rings around ...What if you had tow counter rotating rings around Earth with multiple pinion gears between them. The pinion gears would remain stationary while the centripetal force of the spinning rings would give lift. Now you have the beanstalk but it is only 300 km long instead of 32000. Once you reach orbital altitude, you slide out from the center of the pinion, accelerating to orbital speed.<br /><br />You know... if we're positing all these break through in megaconstructions, maybe we should just build a 200 km tower. Spread it out over 120,000 square km at the base (mostly guy wires) and build up layer by layer until you get out of the atmosphere. Then its just an elevator lift into position followed by a precision rotovator boost to orbital speed.Citizen Joenoreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-77918864460889759062009-07-26T15:17:08.482-07:002009-07-26T15:17:08.482-07:00It should be pointed out that we can build single-...It should be pointed out that we can build single-stage-to-orbit launchers now. It's 1960s-era technology. It's just that they're not reusable SSTOs. The launcher goes up... And it stays up. It's when we start getting into trying to build reusable launchers that we start running into problems.<br /><br />There are launch technologies that work around the problem, leaving the launcher on the ground while only payload goes up. These launch-stations can be as bulky as they need to be, and they can be high-maintenance facilities, because they don't move and it's easy to get a crew to them.<br /><br />Beanstalks take a different approach. They make 'launch' a permanent condition. They're always up and they're always in use. They don't move, but they're not easy to maintain. If anything goes wrong you need to send crews out on blimps and helicopters to repair the lower end, and at the higher end you need spacecraft as repair trucks.<br /><br />The more I think about them, the less practical they seem. But it's hard to compare anything when all you have is study papers and 1/100-scale tests.<br /><br />Ian_MAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-25384724900351091012009-07-26T12:53:52.985-07:002009-07-26T12:53:52.985-07:00As Citizen Joe noted, once you are in orbit, getti...As Citizen Joe noted, once you are in orbit, getting around becomes much easier. (Not <i>easy,</i> but much less difficult than orbit lift!) Low accelerations allow use of high specific impulse drives, or at least smaller rocket engines.<br /><br />The basic problem of surface to orbit lift is that the requirement is so extreme - about 32 megajoules per kg placed in orbit. The result is that any vehicle capable of reaching orbit has to be an extreme design, lacking robustness, therefore expensive and delicate.<br /><br />And there is no real way around this, short of magitech. Which is a real problem for spaceflight.Rickhttps://www.blogger.com/profile/16932015378213238346noreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-47821493275231131022009-07-26T10:56:11.261-07:002009-07-26T10:56:11.261-07:00If we ignore re-entry (maybe some sort of lifting ...If we ignore re-entry (maybe some sort of lifting body design) then the two stage heavy lift vehicle with launch from high altitude can alleviate some problems (maybe). Launching from sufficiently high altitudes (up to 20km) may lower the resistance enough that an accelerating launch vehicle wouldn't need so much heat shielding. Once clear of the atmosphere, a rotovator can do its job and accelerate you up to orbital speeds without the nastiness of air turbulence and mach 20 heat buildup. Once in orbit, various tugs or Jacob's Ladder style rotovators can get you around. Perhaps to the orbiting assembly facility where your dedicated space only vessel gets assembled from parts shipped up. On the way back down, a rotovator can chuck you backwards so that your velocity upon re-entry is subsonic and you basically plummet with braking chutes and glide in. I find the idea fascinating from a mathematical perspective, but terrifying in practice. That almost sounds like an extreme sport, where you time your lift off from the grapple end, then parachute down the 100 km or more to earth. Probably need some sort of ablative emergency escape bubble for at least part of the run.Citizen Joenoreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-82113267050921293162009-07-26T08:14:09.893-07:002009-07-26T08:14:09.893-07:00The US Air Force has been in lust with the idea of...The US Air Force has been in lust with the idea of spaceplanes since the middle of the last century, and before that I think it was the Navy pushing the idea.<br /><br />As far as I can tell, the main problem is that cost-wise it combines the worst of two worlds: A high-performance high-altitude aircraft and a spacecraft/re-entry vehicle. Trying to meet both requirements has so far been impossible and is likely to be expensive even with improvements in the required technologies.<br /><br />Ian_MAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-86910248087184003292009-07-26T06:55:07.358-07:002009-07-26T06:55:07.358-07:00Well I took the speed numbers from diferent source...Well I took the speed numbers from diferent sources found from google. No idea if they are thrustworthy.<br />Althoug the idea of being able to change an object from one orbit to another is a good one. This way orbital vehicles would not need on board engines, reducing launch weight.<br /><br /><br />About lunar elvators:<br />Well, I suppose that if there is already enough traffic in lunar orbit to build an elevator, then an elevator around Earth would already have paid for itself. <br />Not to speak that if there is not an self-sustainable advanced colony in the Moon, a space elevator there would be far more expensive than on Earth (unless take off becomes much cheaper, in this case an elevator would not make much sense).<br /><br /><br />Scramjets:<br />Yes heat would be an important problem. Advanced materials (like titanium aleations and others already used in hypersonic aircraft) could help, but that would increase unit costs, not to speak about reliability problems (like the Shuttle).<br />It seems that space vehicles will have to play with the dilema of unit costs vs. reusability. <br />Maybe the best solution could be something in between like a vehicle designed for a specific number of space fligths which should latter be replaced.Hhttps://www.blogger.com/profile/16142184728794858358noreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-74724441847534833522009-07-25T16:57:09.629-07:002009-07-25T16:57:09.629-07:00I think that the very nature of the rotovator requ...I think that the very nature of the rotovator requires that the end dipping into the atmosphere can't be hypersonic... I'm not even sure if supersonic would work. As it dips into the atmosphere, the turbulence would be too much. A controlled lifting body could probably work at subsonic speeds. They are probably better used for getting stuff already orbiting into higher orbits. Of course, at this point, we've got VASIMR already tested and likely suitable for the orbit changes. So we still need some sort of heavy lift vehicle to get into orbit in the first place.Citizen Joenoreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-38829195116462886082009-07-25T13:59:56.941-07:002009-07-25T13:59:56.941-07:00It's been mentioned that elevators might be bu...It's been mentioned that elevators might be built on the Moon or Mars before Earth, which would (somewhat) get around the issue of scaling the technology up. But obviously that puts the whole thing well into the future, when there is enough traffic at those places to justify less demanding but still pretty spectacular structures.<br /><br />Docking to a rotovator could indeed be tricky. In principle no horizontal motion needs to be involved at the docking point, the rotary motion of the lower end just compensating for the orbital motion, so the hook appears to come straight down, then go straight back up. But that leaves a very short time window to hook on!<br /><br />(The 'flying aircraft carrier' tests with both airships and the B-36 were way cool - too bad they were never able to get it to work very well!)<br /><br />Aerospace planes as an orbit lift solution are very elegant in principle, but scramjets do not seem to have panned out very well. I'd guess that one problem is that if you're flying in dense enough air to provide useful thrust at speeds above Mach 6, the airframe is subjected to a really severe heat bath.Rickhttps://www.blogger.com/profile/16932015378213238346noreply@blogger.comtag:blogger.com,1999:blog-7494544263897150929.post-42260147513319140232009-07-25T07:52:33.714-07:002009-07-25T07:52:33.714-07:00Just some thoughs on elevators and rotovators:
El...Just some thoughs on elevators and rotovators:<br /><br />Elevators: <br />If you look at many recent big infrastructure programs, you can see most of them come gradually. Railroads, for example, started first as short routes which were gradually expanded if they were effective while highways were after all "upgraded roads" and made sense if the volume of road traffic was allready high.<br /><br />A space elevator however would be something totally new that would have to be constructed entirely from zero, there is no possibility to just build half an elevator and later upgrade, it will have to go directly to Geostationary orbit.<br />So it will be a huge initial investment for something that has never before been tested.<br /><br /><br />About rotovators: This has been the first time I have heard about this, and have to say its quite and interesting concept. However if people is worried about the effect an elevator would cause on orbital traffic, then it should be even worse with such a long rotating cable, not?<br /><br />The other problem with a rotovator would be docking in mid-air. <br />There have been multiple attemps in the development of "flying aircraft carriers", and the main dificulty has always been to dock the aircraft on the "Mothership" no matter if it was an Airship or a B-36. <br />If the speeds I have read for a rotovator are fiable, i simply see it highly dificult to dock a plane at speeds between Mach8-Mach12 to a fliying hook midair.<br /><br />As a question: There have been from time to time sugestions of space-aircraft. Vehicles wich take off as regular aircraft and use scramjets to reach the upper stages of the atmosphere, where they use rockets to finaly reach orbit. Would such a system be a reliable replacement for today´s rocket-boosters?Hhttps://www.blogger.com/profile/16142184728794858358noreply@blogger.com