Ye Olde Rocket Forum - View Single Post - A case of overstability?

Quote:

Originally Posted by teflonrocketry1

The pictures in your post are named Cubix. I have created simulations from pictures hundreds of times, one of the reasons my avatar is the #1 certified RockSim user. The drawing you posted doesn't seem to be accurate; what is meant by #20 tubing? I used BT-70 for the main body. I based the measurements I made on the fact the picture shows a C11-3 motor installed (with igniter!). What is the distance of the upper fins from one end of the body tube? If you remove the upper box fins, (should be an easy fix) you get a cool looking tractor design that will fly stable see attached files.

BEC is correct, it's a Centuri #20 from eRockets, 2.042" OD | 2.0" ID | 0.21" thickness. Motor tube is a #9 (basically a 24mm) 0.998" OD | 0.950" ID | 0.024" thickness. Centering ring: Semroc CR-9-20, nose cone: Semroc BC-2025. IIRC the front of the body tube was 2.5" from the leading edge of the upper "fins". The end of the tube was about 0.5" below the trailing edge and the motor protruded another 0.5" beyond that (the pic wasn't to scale, just my initial sketch, which is why I put dimension callouts to remind myself).

Quote:

Originally Posted by teflonrocketry1

A box kite does not fly with its box panels at the angle of attack you used in your design, it fly's with the wind hitting the panels close to a right angle and from their corners.

I just wanted it to look like a box kite and launch straight and safely. In reality it almost DID fly like a kite when it would get sideways, which was never the intention of course.

Can I get a copy of your Rocksim file? (Just started learning how to use OpenRocket and I believe it can read Rocksim files). It would really help me end up with a stable, flyable design.