5,4,3,2,1 and ignition!
Liftoff! The little rocket really jumped off the pad, it's hard to see, but over half of what you see in the above picture is flame.
Click Here for a short video of the flight, in Divx 3.95 MB.
Just about at motor burn out, the rocket lost something and a puff of smoke was seen behind the rocket. If you watch the video you hear me ask what was lost. Not sure what if was, I watched the loose part of the rocket fall, then went back to see where the rocket was heading. The rocket appeared to still be in normal flight. Right at apogee the deployment charge went off and the single chute deployed.
Here's another capture from the video. Not a great picture but as you can see, deployment was perfect.
After the rocket touched down, John and I went to look for the part the rocket had shed, while Joel went out to find the rocket. What John and I found, was the nice shinny aluminum motor, with a small burn through hole near the forward bulkhead. That explained the puff of smoke behind the rocket.
Here is the recovered rocket and motor. I enlarged the burn through area on the motor for better detail.
The motor was such a tight fit in the centering rings, that when the burn through occurred it pressurized the body tube, causing the motor to be forced outward, bending the motor retainer clip and ejecting the motor. This casing material is so thin (.045") there is no margin for error in the thermal liner. I suppose it's possible the motor had some heat damage from the first test that went unnoticed. With an epoxy plug for a forward closure, it's hard to see what goes on up there. It also makes it hard to be sure the thermal liner is in place up there. I had considered making these as single use motors, and perhaps that would be best. Better yet, I think I'll make a real forward closure out of aluminum with o-ring seals.
All in all it was a nice flight, sims put the flight at 2,500'+. The rocket suffered no damage from the burn through, and held up well to the very fast flight and high g forces. So the quickly built, no frills rocket did fine. Even the 6 minute epoxy/surface mounted fins stayed in place. Which, honestly, I wasn't so sure about.
Just in case you're wondering, yes, the motor produced an incredibly long flame trail, longer than the rocket itself. The reason is the fairly high aluminum content in the propellant. In a motor this small, a lot of the aluminum doesn't have a chance to burn inside the motor. So the result is a lot of flame outside the motor. Evidence of this is on the nozzle too, as you can see bright aluminum deposits on the divergent cone. Most motors this small use no, or very low amounts of metals in the propellant formula. I decided to stick with just one APCP formula for the time being, and the 10% aluminum is still giving me better Isp than a lower percent would. Oh, and the big flame/little rocket is fun to watch when you're accustomed to sugar propellants with no visible flame.