Simulation Results
Run the calculator to view results.
Model Rocket Flight Report
Review these findings
Velocity versus time
Flight-path velocity and airspeed.
Altitude versus time
Acceleration versus time
Thrust and drag
Dynamic pressure and Mach
Rocket mass
Velocity versus altitude
| Event | Time | Altitude | Velocity |
|---|
| Phase | Start | End | Duration | End altitude | Maximum speed | Maximum acceleration |
|---|
Browser display is limited. CSV retains every returned row.
| Time | Phase | Altitude | Velocity | Airspeed | Acceleration | Mass | Thrust | Drag | Q | Mach | Cd |
|---|
Calculator Inputs
Choose a quick estimate or configure the complete flight model.
Formula Used
The simulator advances the rocket through small time increments.
Forces and acceleration
Fnet = T − D − mg
D = ½ρvair²CdA
a = Fnet / m
Thrust changes with time. Drag opposes air-relative motion. Mass can decrease during the burn.
State integration
vn+1 = vn + aΔt
hn+1 = hn + vΔt + ½aΔt²
q = ½ρvair²
Smaller time steps provide finer numerical resolution.
Static stability
SM = (CP − CG) / body diameter
This simple check does not model dynamic stability or weathercocking.
Parachute terminal velocity
vt = √(2mg / ρCdA)
The estimate assumes a fully inflated parachute.
How to Use This Calculator
Build a reliable estimate by entering measured values first.
- Enter dry mass, payload mass, recovery mass, diameter, and length.
- Select a motor preset or paste certified time-thrust data.
- Set launch altitude, temperature, pressure, humidity, and wind.
- Enter guide length, angle, friction, and an exit-speed threshold.
- Configure parachute size and deployment behavior.
- Choose a smaller time step for finer resolution.
- Run the simulation and inspect warnings before graphs.
- Compare motors with the same rocket configuration.
- Run uncertainty analysis to study input variation.
- Export CSV, JSON, charts, or a printable report.
Detailed Guidance and Model Limits
Interpret results carefully and verify real flight inputs.
Changing acceleration
A model rocket rarely accelerates at one constant rate. Motor thrust changes throughout the burn. Rocket mass also decreases as propellant leaves the motor.
Aerodynamic drag grows approximately with airspeed squared. Gravity acts during every flight phase. These changing forces make time-step simulation useful.
Burnout and maximum velocity
Burnout velocity is recorded when the entered thrust curve finishes. Maximum velocity may occur slightly before burnout. Late-burn drag can exceed the remaining net thrust.
After burnout, the rocket normally coasts upward. Gravity and drag reduce its speed. Vertical velocity reaches zero at estimated apogee.
Guide-exit velocity
The launch guide controls direction before aerodynamic forces become strong. A slow guide exit can increase wind sensitivity. Longer guides provide additional controlled acceleration distance.
The displayed threshold is a user-selected review value. It is not a universal safety guarantee. Stability, wind, rocket size, and applicable rules remain important.
Drag and Mach effects
A single drag coefficient remains an approximation. Surface finish, fins, nose geometry, launch lugs, and base flow all contribute. Drag can rise substantially near transonic speed.
The Mach-sensitive option adds a simplified drag rise. It is not a full compressible-flow solution. Detailed software or measured aerodynamic data may produce better estimates.
Atmospheric effects
Air density generally falls as altitude increases. Lower density reduces drag. Temperature, pressure, and humidity also affect the density estimate.
Wind changes air-relative velocity and estimated ground speed. Horizontal drift is simplified. The model does not calculate full attitude dynamics or layered wind profiles.
Recovery descent
The recovery model changes drag area immediately at deployment. Real parachutes require inflation time. Shock cords, spill holes, canopy oscillation, and opening loads are not modeled.
Terminal velocity assumes a fully developed descent. Actual landing speed can vary. Use established recovery design practices and suitable field procedures.
Uncertainty analysis
Actual thrust, mass, drag, wind, and temperature vary. Monte Carlo analysis repeats flights with randomized inputs. Percentile ranges reveal how output values may spread.
Wide ranges indicate strong sensitivity or uncertain inputs. Better measurements can narrow predictions. Certified motor curves should replace example data.
Important limitation
This is a one-dimensional flight-path model. It does not model tumbling, fin flutter, structural failure, ignition transients, or complete rigid-body motion. It cannot certify any design or launch.
Follow manufacturer instructions and recognized safety codes. Use approved motors and legal launch sites. Obtain qualified supervision whenever required.
Frequently Asked Questions
Common questions about model rocket velocity estimates.
Is maximum velocity always reached at burnout?
No. Strong drag can make velocity peak before thrust ends.
Why does a lighter rocket not always fly better?
It accelerates faster but can lose velocity faster through drag.
What thrust-to-weight ratio should I use?
Requirements vary. Guide length, wind, stability, and rules also matter.
Why is guide-exit velocity important?
Aerodynamic stability requires airflow after leaving directional guidance.
Can average thrust replace a thrust curve?
It provides a rough estimate. Curves produce better acceleration histories.
Does the calculator support Mach effects?
It includes a simplified transonic drag estimate.
What is dynamic pressure?
It is an aerodynamic loading indicator based on density and airspeed.
Can it predict weathercocking?
Not fully. Complete attitude dynamics are outside this model.
Why does parachute size matter?
Larger projected area normally reduces terminal descent velocity.
What time step should I choose?
Start near 0.01 seconds and refine sharp thrust changes.
Can results be exported?
Yes. Export CSV, JSON, chart images, or printable PDF reports.