Apexline is an offline flight computer for model rocketry. Enter your rocket, pick a motor — or import its measured thrust curve — and see predicted apogee, the ejection delay to install, rod-exit speed, stability and recovery before you go to the field.
NEW IN 4.0
• Import measured thrust curves: open RASP .eng files from ThrustCurve.org or a manufacturer and Apexline flies the measured curve in every calculator.
• Launch Day: go/hold checks for your rocket and planned motor, a prep checklist saved per rocket, and a printable PDF flight card for the range safety officer.
• Flight log vs prediction: log altimeter apogees and Apexline fits your rocket's drag coefficient to every logged flight, then applies it in one tap.
• Motor comparison: fill a comparison with motors that fit your rocket's mount and rank them by apogee, thrust-to-weight, rod-exit speed or delay match.
• Stability at liftoff and burnout, with the motor's mass placed at the tail.
• Backup & restore of rockets, flights, imported motors and checklist progress in one file.
• Motor catalog re-checked against ThrustCurve.org, and launch-site sizes updated to the NAR safety-code table.
PREDICT THE FLIGHT
RK4 flight simulation with ISA air density for your site altitude and temperature. Apogee, optimum and recommended ejection delay, max velocity, peak G, burnout altitude, thrust-to-weight and rod-exit speed, with altitude and thrust-curve charts. The physics is checked by unit tests against closed-form flight solutions.
MOTORS
Built-in catalog of Estes, Quest, Klima, Apogee and AeroTech motors from 1/4A to J, a motor-code decoder, and your own imported motors.
STABILITY
Barrowman center of pressure from your nose and fin geometry, static margin in calibers with the motor loaded and at burnout, and a CP/CG diagram.
RECOVERY AND FIELD
Descent rate, chute size for a target descent, landing energy, drift from the predicted apogee, dual deployment, and safety-code field size.
MORE TOOLS
Two-stage and cluster planner, flight-duration planner, fin flutter check, wind and launch angle, target-altitude ballast solver, Cd calibration, guides and glossary.
PRIVATE BY DESIGN
No account, no subscription, no ads, no network. Your rockets and flights stay on your device. Share designs, flight cards, CSV logs and backups as files when you choose.
Predictions are estimates. Always follow the safety code, the motor instructions and your range safety officer.
iPhone and iPad.
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