Model Rocket Altitude Calculator
Enter your motor's average thrust, burn time and the rocket's loaded mass to estimate burnout velocity and peak altitude. This is a no drag model, so treat the result as an optimistic upper bound. A real flight will reach a lower altitude.
How to estimate your rocket's altitude
- Enter the average thrust in newtons and the burn time in seconds from the motor data sheet.
- Enter the loaded liftoff mass in kilograms or grams.
- Read the burnout velocity and estimated peak altitude in metres and feet.
Examples
Light rocket on a sustained burn
thrust = 10 N, burn = 1.5 s, mass = 0.1 kg
burnout = 135.3 m/s, peak = 1034.7 m (3394.6 ft)
Small motor in a mini rocket
thrust = 5 N, burn = 1 s, mass = 0.05 kg
burnout = 90.2 m/s, peak = 459.9 m
Frequently asked questions
Does this account for air resistance?
No. This is a no drag kinematic model, so it is an optimistic estimate. A real rocket reaches a lower altitude because drag bleeds off speed during boost and coast.
How is the altitude worked out?
In two phases. During boost, net acceleration is (thrust minus weight) over mass, giving burnout velocity and boost height. During coast, gravity alone decelerates the rocket to apogee, adding velocity squared over 2g.
What is burnout velocity?
It is the speed of the rocket at the instant the motor stops thrusting. From there the rocket coasts upward, slowing under gravity until it reaches its peak altitude.
Why does it need thrust greater than weight?
If average thrust does not exceed the rocket's weight, the rocket cannot accelerate upward off the pad, so the model has no valid boost phase and reports an error.
How far off is the no drag estimate?
It depends on the rocket. Sleek, heavy rockets come closest, while light, fast or draggy rockets can reach well under half this figure. Use it as a ceiling, not a prediction.
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