>>11109832> copying a cold war designwew.
i'm a crazy stranger on the internet, so it's not my fault if you injure yourself.
i'll help your amateur rocket break records and save you a bunch of trouble.
KEEP IT SIMPLE
NO NEW TECH
NO COMPLICATED TECH
NO EXPENSIVE TECH
NOTHING YOU CAN'T BUILD IN YOUR GARAGE IN UNDER 4 HOURS
BE HUMBLE
Get the biggest carbon fiber tube that is available as a COTS item.
Get solid propellant mix that has been used by hobbyists and proven to work.
Get a nozzle that has been used by hobbyists and proven to work.
Don't use any steering, it's too complicated.
Don't use a single thing that hasn't been used successfully by at least 4 unrelated projects.
Use an existing design for a large-scale rocket that's like a scaled-up Estes model (spin stabilized, launch on a launch rail, solid propellant, parachute recovery).
Before buying anything, build a complete model of every key part of the system. originality = mistakes. keep it simple. use equations (for performance calcs) or procedures (for safety) that have been used by at least 3 other successful teams.
Things to consider:
- safety: how far away do you need to be to avoid shrapnel if it fails? how to avoid igniting the propellant during shipping? how to avoid airspace violations? your opinion doesn't matter. the opinion of the regulators is what matters.
- stability: center of gravity ahead of center of pressure.
- maximum pressure of combustion gases, safety factor for your carbon fiber tube including all glue joints. use peel strength, not shear strength.
- exhaust velocity.
- nozzle durability.
- ballistics (range, max. altitude, flight time, etc.)
- verification tests for each component (don't skip this). measure mass and cg. hang from cg and put in air stream to verify it's aerodynamically stable. attach to test fixture and test fire on the ground to verify everything.
- cost to build -- multiply by 2
- time to build (labor) -- multiply by 4
Proceed only if all the above is OK
