Flyers are REQUIRED to insure a safe flight profile for their rockets.
NOTE: The RSO will have final say whether the rocket can fly with the installed motors! If you select a motor that will give an unsafe flight profile (too little thrust for rocket weight), or is judged to be in danger of exceeding our waiver, you will NOT be allowed to fly. If you have questions, please consult the METRA Prefect or President.
Acceptable Thrust to weight(rocket and installed motors) ratio:
A minimum ratio of 5:1 is typically required. This can be as low as 3:1 at the RSO’s discretion. This decision will require low ground level winds and stable design (Cg more than 1 caliber ahead of Cp).
A 5:1 ratio is determined simply by taking the rocket weight(loaded with motors) in pounds and multiplying by 22.25 to get minimum required motor thrust in Newtons (N). Note this is the motor thrust off the pad, not the motor total thrust. Minimum required thrust can be read off these charts: