So...we're getting ideas from Pixar now?
Maverick Pentagon crazytech agency DARPA has awarded itself a firm pat on the back after a detailed examination of its second HTV-2 test flight last year, in which the high-tech Mach 20 glider was destroyed 9 minutes into the trial and crashed into the Pacific. Concept art showing the HTV-2's fairing opening after ascent …
So...we're getting ideas from Pixar now?
I would have said David Braben .
(...) hypersonic technology (...) could be useful for (...) truly re-usable and economical orbital spaceplanes.
I can't see how.
I mean, if the thing still has to be launched from a rocket, how is it any better than current launcher vehicles and the retired space shuttle?
The test plane has to be launched from a rocket but, so what? The first supersonic plane the Americans flew was just a rocket with wings.
They're learning the aerodynamics first. There's no point in developing the engines for a hypersonic craft if it's going to fall apart when you turn them on.
The retired Space Shuttle was far from economical and barely reusable. It relied on thick and very expensive heat tiles to protect it during reentry. If (and when) these fail, the result, as we sadly have all seen, is catastrophic. Research into alternative materials which can withstand the rigours of hypersonic flight may well yield something both cheaper and hardier.
The test plane has to be launched from a rocket but, so what?
So... It hasn't brought anything new to the table, as far as escaping the gravity well is concerned.
And if what you want to do is just send stuff around the Earth real fast, sub-orbital rockets can already do that; why don't go the extra sub-orbital step, if you're going to use a rocket anyway? What bothering with "gliding" on the higher atmosphere and all related problems (heat etc.) buys you?
This is an honest question. If there are economical / tactic advantages to gliders over sub-orbital launchers, I'd like someone to enlighten me.
The goal is a self-propelled aircraft that can get from point A to point B in a very short period without leaving the atmosphere. A sub-orbital rocket can get from A to B pretty fast but once you know where it's from and what it's trajectory is, you can make a fairly accurate guess of where it will go and take countermeasures. An aircraft that can move at a significant chunk of the speed of a ballistic missile yet which is capable of changing direction would negate that completely. Its target would be unpredictable.
Like I said, they're testing the aerodynamics of the vehicle, not the actual vehicle itself. The eventual goal is a hypersonic jet aircraft, manned or unmanned, that can get to anywhere on the planet in just a couple of hours.
A hypersonic plane could also theoretically get most of the way out of the atmosphere without using much fuel. Scramjets could take it to the edge of space, then a rocket could take over from there. It would save the entire first stage of a launch system in theory. That's a huge saving.
Can't do any of that unless you know it's going to actually fly, hence the rocket-launched drones.
We blew it up, Hooray :D
I have a framed copy of this: http://wondermark.com/634/ on my desk. So excellent.
DARPA, finding new ways to con... err convince the U.S government to fund research by saying it's for bombs!
And I suppose other governments around the planet aren't funding research for bombs?
A control system that can cope with bits breaking off at mk20 is epic. I for one think this is actually a huge advancement of aerodynamics that just cant be recreated in a wind tunnel. I hope they get to do more launches. It pains me that people forget recent history, how many attempts did it take to get just a rocket into space? This is really complex stuff that's pushing the boundaries of what we know, what we can simulate. If we can crack hypersonic aerodynamics scram-jets can become a reality and that will make concord seem as quick as an airship...
Shame good science has to hide behind bombs.. but so is the American way and who else has the budget and expertise to do this kind of work?
> the US military would like to be able to deliver a warhead to any spot around the planet in less than an hour.
Whereas most other global purveyors of firey death would be happy to wait an extra day or two and send it by a more traditional means: DHL, anonymous shipping container, back of a Transit, etc.
Still, I suppose when you simply have to make the 6 o'clock news, extreme measures are necessary
basically we are guilty of exactly what we criticize N.Korea's space program for, right?
So what about "delivering a warhead to any spot"? Can the US military research "delivering a warhead to the correct spot" instead?
to get from airport queue to airport queue really fast.
Just for comparison – how fast was the shuttle going in similar atmosphere? How high up was DARPA's glider?
Sorry if I missed something.
a quick check of wikipedia says this about reentry: "The vehicle started encountering more significant air density in the lower thermosphere at about 400,000 ft (120 km), at around Mach 25..." But that was while drastically slowing down, unlike the DARPA thing which continued to haul ass for a while.
I think that going that fast is pointless anyway. The view won't last anything like long enough for the trip to be worthwhile. Far better to get up into orbit and stay there for a few revolutions at least, and spend a whole lot more time looking out the window.
The view being of Alpha Centuri getting ever larger...
Hard to tell- what version of speed are you using? True air speed is hard to calculate, ground speed isn't really the most relevant to AEROdynamics, and mach speed varies with air pressure and other factors.
Mach speed is the most relevant to the physics involved, but Indicated Air Speed would be best. It's just impossible to measure without a pitot tube, which itself breaks hypersonic aerodynamics.