Ye Olde Rocket Forum - View Single Post

Quote:

Originally Posted by CPMcGraw

In the simulation drawing, I used a 6" motor mount, but installed the motor block at 3.5" from the rear of the tube.

The E15-7 is one of the motors I used in the list. The simulator hit 1518', and reached speed at 36.25". Still needs the 48" rod.

Best altitude was with the F24-7, with 1719'. Speed was reached at 27.2", meaning you can squeak by with a 36" rod here. I'd still use the 48" rod for the additional speed before free-flight.

Craig McGraw

Hmm.. I noticed on a couple of my D12 flights that my previous 'Roc seemed to "hang" momentarily just off the rod. I wonder if rockets like this and the Mean Machine may actually have such long moments on their CG that they have a bit of "inertial stability" that resists changing direction even if they haven't quite reached aerodynamic stablility off the rod. Not that I wouldn't use a 48" rod just to be safe, but wonder what your thoughts are on this.

The reason I started considering this idea in the first place is because the Thunder Roc would be easy to see at higher altitudes, with a better chance of recovery. Still, a calm day is a must if it's going to 1500'. I went with dual 18" chutes on the last one and never broke a fin, though I DID walk a quarter mile to recover one day with 10 MPH winds. (Where's the emoticon for "exhausted"?)