Apexline: Rocket Simulator

Model rocketry throws the same questions at you on every launch: how high will it go, which ejection delay to use, will it fly straight, and what parachute it needs. Apexline is a flight computer for answering them out on the launch field, whether you fly Estes kits with your kids or build your own designs.

Enter a rocket's mass, diameter, and drag, pick a motor, and it simulates the boost, coast, and climb to apogee, factoring in your field altitude and the air temperature. It works out the optimum ejection delay so the chute deploys near the top rather than too early or too late, and it uses the Barrowman equations to find the center of pressure and report your stability margin in calibers.

There is a built-in catalog of common Estes, Quest, AeroTech, and Klima motors, a decoder for reading a code like C6-5, a parachute sizer that estimates descent rate and downwind drift, and a launch readiness card that folds everything into a single go, caution, or hold check. Twelve illustrated guides and a glossary cover the hobby from motor codes to recovery.

Apexline runs entirely offline, with no account and no ads. It is a planning and estimation tool: always confirm against the certified motor data and follow the Model Rocket Safety Code.