=scratch= Two Stager, the Twin Shark

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Jan 18, 2009
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Houston, TX
Apparently I like to start projects but have a hard time completing them, because even though I have at least 5 rockets in the build queue right now...

I'm working on a 2-stage model that my son Thomas drew on a piece of posterboard, called the Twin Shark. The fins on the booster and sustainer, three fins on each, will be shaped like a shark's dorsal fin. I'm planning to build it from BT-60 tube with a Big Bertha style nose cone. This will be the first 2-stage rocket that I've built, but I have done a decent amount of reading on getting staging to work with a gap between the booster and sustainer motors. As things stand now, the booster motor tube will reach almost to the end of the sustainer motor, and there will be vent holes in the booster to keep it from popping off prematurely. The stages are held together by a coupler.

According to the Rocksim v5 demo that I'm still using, the best motor combinations are: B6-0/A8-3, max. altitude of 341 ft, deployment speed of 11.85 ft/sec
B6-0/B6-4, max. altitude of 471 ft, deployment speed of 10.65 ft/sec
C6-0/A8-3, max. altitude of 532 ft, deployment speed of 21.71 ft/sec
C6-0/B6-4, max. altitude of 649 ft, deployment speed of 6.05 ft/sec

A8-3, B6-4, and C6-3 are the best motors to use for single-stage flights.

My son, who is 9 years old, asked me if he could sell his rockets and make money from them, and I told him we might be able to do that at some point, in really small quantities.

He's also the designer of the Demon Rider, a BT-60 rocket with a black ogive nose cone, a red paint job, and 4 fins shaped like the arrowheads on the end of a devil's tail. I've flown that one at past Challenger club launches, at NARAM-50 last summer, and at Cub Scout day camp this summer, when our local Mr. Rocket Andy Berger did his rocket demonstration for the Cub Scouts.