Wednesday, July 15, 2009

Still More Speeeed!

Via Atomic Rockets, from Wired, this footage of a Falcon I rocket on its way to orbit with a Malaysian satellite.



The Monday launch was carried out by SpaceX, a private company looking to carve out a place in the commercial space launch market. I will bloviate about the public and private sectors in space at some other time. For now, just strap on and enjoy the ride.

The view shifts to an onboard camera just after launch. Note what happens to water droplets on the camera lens as the vehicle passes through Mach 1, and what I assume is the red-hot glow of the second stage engine nozzle throat.

14 comments:

Anonymous said...

Okay, forget the high-speed train. I want one of these.

It would be entirely practical for my morning commute.

Ian_M

Rick said...

You commute to orbit?! :-)

Calsir said...

There is at least one field where they already beat NASA: they give readouts in the SI :D. Ok, I don't mean to begin a flame war or anything, I am just ranting.

Rick said...

I don't think even us 'Murricans will give you a flame war about NASA's use of medieval units. Especially since NASA uses feet per second, not an everyday measurement.

All I can guess is that it is a 'legacy' thing. The engineers actually involved are accustomed to it, at any given moment all the documentation uses it, so changing over would be a hassle.

Of course we remember what happened to that Mars mission ...

Anonymous said...

Rick - No, but I'm pretty sure I could land a capsule somewhere near downtown without killing too many people. Entirely practical, I say.

The US still uses 'customary units' because right now the US is (Still, kinda sorta) in a position to force the rest of the world to adapt to US practices. Want to do business with the US? You have to go to the extra cost to translate your measurements into foots (Feets?) and pounds. At some point that virtual tariff will reverse effect, and the US will have to pay an extra cost to do business with the rest of the world.

Or switch to metric. Counting by tens is easy. Join us. Don't be afraid...

Ian_M

Rick said...

It certainly would put the 'rapid' in rapid transit! (The town of San Luis Obispo, near here, actually labels its buses SLO Transit.)

Oh, we'll eventually go metric, perhaps even in this millennium. Just don't expect us ever to start calling soccer 'football.'

I do space related calculations routinely in metric - it helps that 1 g is so close to 10 m/s/s. But when I wrote the SpringStyle battleship design sim, and a plane sim, I actually did internal calculations in metric, but converted them to 'Murrican units for I/O. Spacecraft dimensions in metric seem entirely right and natural, but I'm accustomed to ship and plane dimensions in feet!

Calsir said...

"I actually did internal calculations in metric, but converted them to 'Murrican units for I/O. Spacecraft dimensions in metric seem entirely right and natural, but I'm accustomed to ship and plane dimensions in feet!"

Well, I am used to psf (pounds per square foot) when dealing with wing loading (it is a pressure).

Also, I don't personally like the definition of the metre (1e-7 of the quadrant of a meridian) since it uses the centesimal degree, which was used by French artillerists. I would personally have preferred something based on the nautical mile, which uses the sexagesimal degree system. That is, 360*60 nmi form (more or less, due to current definition) the whole meridian.

Of course, neither measure is more "rational", as the partition of a circle in "degrees" is fairly arbitrary. I do think that the knot (kt, nmi/h) is a "better" unit to measure velocities on earth, rather than kph or mph, since it is more closely related on how we express locations on Earth surface. Of course, it would make no sense on Mars :). Besides, when you are in an atmosphere, Mach and Reynolds number are much more interesting.

Rick said...

With wing loading, as with ship/plane dimensions, it is largely a matter of familiar benchmarks.

Interesting point about distance measurement. Had the designers of the metric system chosen to go with angular measure, the choices would then presumably have been either to make the base unit 1/1000 of a minute of arc, about 1.8 m (a 'metric fathom'), or 1/100 of a second of arc, about 0.3 m (a 'metric foot').

Calsir said...

"With wing loading, as with ship/plane dimensions, it is largely a matter of familiar benchmarks."

Still, I should be a good metric euroboy.

"Interesting point about distance measurement. Had the designers of the metric system chosen to go with angular measure, the choices would then presumably have been either to make the base unit 1/1000 of a minute of arc, about 1.8 m (a 'metric fathom'), or 1/100 of a second of arc, about 0.3 m (a 'metric foot')."

Actually, they did use an angular measure: the decimal degree (grad or gon), that puts 400 gon in a circle, or 100 gon in a quadrant. A kilometre is nothing more than the 100th part of a gon. I supposed they liked it better because it was more "rational", as in more decimal :). Besides, I'd call 1/1000 of a minute of arc the "nautical metre", since the nautical mile is defined as equal to the length a prime of arc (at a certain latitude).

Of course, there is also the reason that I am allergic to "foot" and "fathom" ;-). When I have to give directions to Americans, I think in metres and speak in yards, with a conversion ratio of 1:1 :).

Rick said...

Handy benchmarks trump theoretical principles! That's why the hard core SI zealots will have a hard time getting rid of AUs and light years / parsecs.

I've heard of grads, but 'gon' is a new one to me. We'd all be in a real mess if they'd metricized time - well, they did, some, for longer units, but everyone still has the good old second.

And yes, yards and meters provide a handy approximate equivalence!

Jean Remy said...

The metric system (or SI) has its origins in the French Revolution (before that it was league and foot and the like) But the revolutionaries were so fanatical they wanted to revamp everything into metric. Success has been, suffice to say, uneven. Meters, liters, grams, and degrees (centigrade a.k.a. Celsius: temperature not arc measurement) have not only survived but thrived, and are now (nearly) universally adopted. Grad degrees seem to have an uneasy truce with their non-decimal brethren. However decimal time, (yes they did try to introduce a decimal clock) and their calendar (who still knows what 3 Thermidor means?) have been all but forgotten.

Rick said...

Oddly enough, Thermidor (I assume it corresponded roughly to August?) is the one Revolutionary month whose name is still at all familiar, because of the 'Thermidor period' of moderation after Robespierre had his face-up encounter with Mme Guillotine. Whence it has become a standard term for similar phases in other revolutions.

Jean Remy said...

To be honest I really just used Thermidor off the top of my head without realizing that it actually was the one month whose name had indeed survived. Pluviose or Germinal might have been better examples.

It was actually mid-July to mid-August roughly. Every month was a 30 day period split into three ten day periods called "decades" rather than the 7 day week, named Primdi to Decadi, (not to be confused with what we call a decade: 10 years) Five or six "Compensatory Days" were tacked on to the end to make it catch up with the solar year. Because there was also an attempt at overthrowing the Catholic Church days were stripped of their saint's names and given common noun names, and the day of rest was Decadi rather than Sunday. (reducing the number of rest days by a significant margin. An unkind soul might suggest perhaps one of the reason it was rejected?)

When the Roman Catholic Church reasserted its power the structure of weeks was one of the first things to come back, and the whole of the calendar would not survive for much longer. It was in use for a grand total of twelve years.

Rick said...

Reducing the number of rest days was not much of a grace note on the part of the calendar's designers!

Another bit of calendric trivia. When England switched over to the Gregorian calendar in the 18th century there were riots by workmen saying 'Give us back our eleven days!'

But they had good reason to riot - rents were not pro-rated for the shortened month, so they had to pay a full month's rent, while their income for that month was reduced by more than a third.