Today was the day I got impatient with some stuff that I built and haven't had a chance to fly yet. So I loaded up a few rockets, walked them down to the local schoolyard and launched the stupid things already.
It's a small field, and not ideally shaped, so these are all (except one) flying on B6-2 engines when they would probably be better served by Cs.
The Goony Saturn V
I've flown the Loony Module and the Goony Saturn 1B already, but for one reason or another the Saturn V has been just sitting around. It flew basically perfectly:
The USS Orpheus
It flew pretty well, but it's definitely following the rule that the more work you put into the finish, the more damage the rocket will sustain. It managed to find the one bit of asphalt in the grass playground and land on it, breaking off one of the pylons at the fin root. Fortunately it was a clean break on the internal joint so I think it will glue back together.
One thing about rockets like this one where the parachute is held around a spool, it takes about an extra second after ejection for the chute to really deploy (that's if I fold the chute and place it in a C shape around the spool, it would probably take a lot longer if I wrapped the chute all the way around). This can be a good thing because you get less drift with a large parachute, kind of a poor man's dual deploy setup. But here the combination of the low total impulse and the longer delay means the parachute didn't fully open until about 50 feet up or so. The rocket would probably have survived better if I'd flown it higher.
The Quick n Dirty Space Shuttle
I was worried about how this one would perform, because it's a testbed for my first attempt to scratch build a parasite glider. I guess I shouldn't worry, because it flew great. Boost was quite straight, separation at apogee worked properly, and the glider basically glided. The glide slope was pretty steep, maybe as much as 30 degrees, but that's not surprising since it's heavy and draggy and doesn't have a lot of wing area. It could probably benefit from being rebalanced with the CG a little farther back. But a nice stable spiral glide to a safe landing.
I wish I had enough hands to get video of this one.
0FNC
This is part of a series of aerodynamics tests I'm doing. It's a finless rocket with a lot of nose weight flying on a 1/2A3T. It doesn't fly very high, and it landed hard (really shouldn't use streamer recovery on something this heavy) but it flies straight up.
So this confirms, the center of pressure on a (subsonic) rocket body is about 1/4 of the way back, just like the CP of a wing or fin. It's not up at the nose like OpenRocket says. Kind of figured it would be based on theoretical concerns, but it's nice to have data.
To get a rocket like this to have the CG that far forward, you need nose weight about 3x the motor weight, which in this case cam by gluing a 3/8 bolt and some nuts into the nose cone.
It's a small field, and not ideally shaped, so these are all (except one) flying on B6-2 engines when they would probably be better served by Cs.
The Goony Saturn V
I've flown the Loony Module and the Goony Saturn 1B already, but for one reason or another the Saturn V has been just sitting around. It flew basically perfectly:
The USS Orpheus
It flew pretty well, but it's definitely following the rule that the more work you put into the finish, the more damage the rocket will sustain. It managed to find the one bit of asphalt in the grass playground and land on it, breaking off one of the pylons at the fin root. Fortunately it was a clean break on the internal joint so I think it will glue back together.
One thing about rockets like this one where the parachute is held around a spool, it takes about an extra second after ejection for the chute to really deploy (that's if I fold the chute and place it in a C shape around the spool, it would probably take a lot longer if I wrapped the chute all the way around). This can be a good thing because you get less drift with a large parachute, kind of a poor man's dual deploy setup. But here the combination of the low total impulse and the longer delay means the parachute didn't fully open until about 50 feet up or so. The rocket would probably have survived better if I'd flown it higher.
The Quick n Dirty Space Shuttle
I was worried about how this one would perform, because it's a testbed for my first attempt to scratch build a parasite glider. I guess I shouldn't worry, because it flew great. Boost was quite straight, separation at apogee worked properly, and the glider basically glided. The glide slope was pretty steep, maybe as much as 30 degrees, but that's not surprising since it's heavy and draggy and doesn't have a lot of wing area. It could probably benefit from being rebalanced with the CG a little farther back. But a nice stable spiral glide to a safe landing.
I wish I had enough hands to get video of this one.
0FNC
This is part of a series of aerodynamics tests I'm doing. It's a finless rocket with a lot of nose weight flying on a 1/2A3T. It doesn't fly very high, and it landed hard (really shouldn't use streamer recovery on something this heavy) but it flies straight up.
So this confirms, the center of pressure on a (subsonic) rocket body is about 1/4 of the way back, just like the CP of a wing or fin. It's not up at the nose like OpenRocket says. Kind of figured it would be based on theoretical concerns, but it's nice to have data.
To get a rocket like this to have the CG that far forward, you need nose weight about 3x the motor weight, which in this case cam by gluing a 3/8 bolt and some nuts into the nose cone.
