Everything you need to go from zero to a completed flight simulation — motor loaded, geometry entered, results in hand.
Navigate to the Simulator page and Project APEX loads immediately. The interface has three main areas: the sidebar on the left for inputs, the summary bar across the top for key metrics, and the chart panel on the right for results.
You have two options for loading a motor:
Option A — Search ThrustCurve: Click the Motor DB button in the top bar. Search by name, impulse class, or manufacturer. Click any result to preview its thrust curve, then click Load . Over 4,700 motors available.
Option B — Drop a .eng file: If you have a RASP .eng file , drag and drop it onto the motor drop zone in the sidebar. The thrust curve is parsed instantly.
Once a motor is loaded, the motor badge in the header shows the motor name, class, total impulse, and burn time. The thrust curve preview appears in the sidebar.
Navigate to the Simulator page and Project APEX loads immediately. The interface has three main areas: the sidebar on the left for inputs, the summary bar across the top for key metrics, and the chart panel on the right for results.
| Parameter | What to enter |
|---|---|
| Airframe diameter | Outer diameter of the body tube |
| Rocket length | Total length from nose tip to base |
| Nosecone shape | Ogive (most common), Von Kármán, conical, or parabolic |
| Nosecone length | Length of nosecone section only |
| Fin root chord | Fin length where it meets the body |
| Fin tip chord | Fin length at the tip (0 for triangular fins) |
| Fin semi-span | Distance from body to fin tip |
| Launch mass | Total mass including motor (with propellant) |
| CG position | Distance from nose tip to centre of gravity |
Click the orange Run Simulation button in the header. The RK4 integrator steps through the full flight at 0.05s intervals from launch through apogee and descent. Results appear immediately.
The summary bar at the top shows your key metrics at a glance: apogee altitude, peak velocity, peak Mach, peak acceleration (G-load), burnout altitude, coast time, and stability margin. Colour coding indicates whether each value is in the expected range.
The chart tabs give you the full flight profile:
Flight tab — altitude, velocity, Mach number, and acceleration vs time. Peak annotations show exact values and timestamps.
Aerodynamics tab — Cd vs Mach curve, drag component breakdown, Reynolds number, and dynamic pressure.
Stability tab — CP and CG positions tracked through the flight, stability margin in calibers, and fin geometry reference.
