Maximum Recommended Liftoff Weight

Why doesn’t Roadrunner provide a maximum recommended liftoff weight for each motor-delay combination as some motor manufacturers do?

Well, it is really pretty simple – maximum recommended liftoff weight is complicated! Apogee Rockets has a great technical article on this very subject at

Simply put, for a given motor-delay combination there is no one maximum recommended liftoff weight that applies to all rockets and launch conditions. Accordingly, providing a maximum recommended liftoff weight would either be misleading, or calculated so conservatively that it would preclude launches that should work fine.

Instead, Roadrunner believes rocketeers should use available tools to educate themselves and determine the appropriateness of a motor for a particular flight. There are numerous resources available to rocketeers including flight simulators, the kit manufacturer’s motor recommendations, rocket related web sites, and EMRR reviews ( among others.