Friday, December 23, 2011

The full story of Stig-A from Armadillo Aerospace

"On Sunday morning, 4 December 2011, Armadillo Aerospace launched the tube rocket "Stiga" (aka STIG-A) to approximately 140,000 feet above sea level from Spaceport America. The rocket took just under 2 minutes to reach apogee and landed twelve and a half minutes after the launch. The landing point was 2.87 miles away from the launch pad and conveniently on a road, well within the 4.35 mile range established before the launch."

How great is this rocket? Only mach 2.87 and 140,000 feet! The efficiency of a slow burning rocket with active guidance is very clear. The rocket shut down more than 10 seconds early because it had passed a pre-arranged downrange distance. That is a great safety feature, and also means that it could have broken mach 3 and gotten closer to 200,000 feet if it burnt the tanks dry. (The last 10 seconds would, assuming no throttle or great loss in motor isp at high altitude, be the best 10 seconds of all.) In fact, with a bit of optimization, this rocket could carry payloads to space. That could be as simple as a slightly lighter air frame, a bit more fuel, or a better ISP.

This would be an idea booster stage to a dumb solid rocket motor, say a Q, if they are interested in getting payload to 500,000 feet + at some point. Lighting a Q at 90,000 feet and mach 2 would be more than enough to get 10kg of cameras to 500,000 feet. But that is just my gut reaction, always being obsessed with altitude. It is quite possible that they have other things in mind (such as larger payloads.)

The recovery worked well enough (damage was noticeable but not fatal) but the parachute systems are going to be redesigned in future. The drogue stage is based on a large ballute. Ballutes are ideal for high-mach conditions, but in this case the drogue was damaged, resulting in a high speed deployment for the main chute, also resulting in damage. For my 2 cents, I suggest a 6 ft rocketman kevlar 'chute or the 8 foot ballistic mach II 'chute for this purpose.


1 comment:

Dick said...

Nice summary and commentary. And, thanks for the link back.