Are you ready to have a competition?
I've performed many competitions and the safest is down range distance like at a football field using limited air pressure.
Any apogee competition will likely fall way short of using a recovery system. The likely nosecone of choice will be sharp. The likely result will be fast falling pointed objects coming back your way. Been there, dodged that. Requiring a recovery system is a valid way to deal with the problem.
Rules will be the biggest deal for the competition. I would recommend these basic rules:
1) must use a soda bottle (you could even specify the volume)
2) no cutting or changing the shape of the soda bottle (for safety reasons and time constraints. modified pressure containment needs hydrostatic testing) (glues to the pressure vessel should be compatible with PETE)
3) no modified nozzles (saves from having to dodge corkscrew flights)
Rules like that will force students to work with aerodynamics, rocket stability, and power to weight ratio.
How far could you make a rocket go with only 50psi using a 22oz soda bottle?
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