No we were all passive on the way up. Anything over a 3 degree angle below 3 km and a 5 degree angle below 8 km caused an abort. We used a simple reaction wheel to stay as vertical as possable. It only sort of worked as it could only handle very minor shift in angle. We had to have a 15m tower and a back yard bungee setup to get the rocket going fast enough to where it was aerodynamically stable. Also surface winds had to be under 8kph. All the practice launches with solid motors and full weight were within limits to 3.5K altitude. Our altitude range was from 16 km (the goal) to around 18.km for a vertical flight. the goal was set way back in 2004 when the highest rocket that had flown successfully at the time was a big N to about 13.4km. Our goal was a peroxide O motor to 16km
Robert At 02:23 AM 11/16/2013, you wrote:
There's definitely a drag loss vs gravity loss trade off. I forget, were you gimbaling or steering with fins, or what? Ben On Saturday, November 16, 2013, wrote:The reason I asked was that the software we first used with the Condor Project spit out a solution to our problem of not building a tank to get to 16+ km, which was the goal, was to throttleable back the motor. As a bonus, it actually gave us a little bit more altitude than going full bore. in the sim, We ran full throttle at 450 lbf for 9 seconds and then went down to 110lbf for the next 60 seconds or so. The sim shows us hitting mach .92 at throttle back and then slowing down to about mach .83 before gaining speed again and going through mach a about 11Km. The rocket using this flight profile was 26% lighter and got 10 to 15% higher than a sim of the same design but full throttle until burn out.I understand the problem with solids but there has got to be a way to keep it under mach in the initial boost stage so that going through mach and heating is just not an issue anymore.Robert At 06:22 PM 11/15/2013, you wrote: On Fri, Nov 15, 2013 at 4:19 PM, <qbert@xxxxxxxxxxxxxxx> wrote: > After going through several space blog updates I ran into a Sugar Shot to> Space blog which then led me to Bens Brokets assessment of heat vs speed and> altitude. The question I have, would it not be better to go slower though > the lower atmosphere, say up to 40,000, or even 60,000 feet until > approaching mach lessening both the dynamic forces and heating. > > Robert If the thought "would it not be better to go slower though the lower atmosphere" is run as far as possible, the usual conclusion is "let's build a rockoon" or "let's build a space elevator". But going hypersonic at 13km isn't impossible, it just takes some attention to materials and design. Ben
