D-400 Purger Missile

This is a recoverable rocket with folding fins. It was a lot of fun building this thing. I would like to warn you though about hairline fractures developing in the airframe if you print too fast. Also to make sure that cracks don't develop around the screws and tail fins, you're going to want to heat stake all of the holes on the outer airframe then you can screw the body together using the stakes you just seated. The rocket motor is a class E motor at 29mm with a total impulse of about 20 to 40 newton seconds (burn time). Do the string test to make sure the rocket is balanced. Have enough wadding to protect your piston. Keep a close eye on the fins. You don't want them breaking from the sudden inertia. (stake holes in the fins too)