Rocket Launch Trajectory Simulator — How it works

An interactive 2D physics simulation of orbital mechanics and rocket launches from Earth. Realistic atmosphere, variable thrust, drag, and a closed-loop guidance system.

Game modes

Choose a mode from MENU before launching.

• Manual control — You control pitch with W/S (or on-screen buttons). Guidance shows recommended pitch in cyan. Good for learning.
• Guided launch — Set a target altitude (150–2000 km). The guidance system flies the rocket and circularizes the orbit automatically.
• Orbital mode — Start already in orbit (200–800 km presets). Practice prograde, retrograde, normal, anti-normal, radial, and anti-radial burns. Use REFUEL to add propellant.

Controls

Vehicle Hangar (custom rocket)

Open the Vehicle Hangar to design a two-stage rocket: stages, payload, fairing, thrust, and mass. Your design is saved in the browser and applies the next time you start a mission from the launch pad. Use BUILD › in Mission Control or the Hangar link at the top of the simulator.

Telemetry

Real-time data: T+, stage, altitude, downrange, velocity (vertical/horizontal), acceleration, Max Q, dynamic pressure, drag coefficient, Mach, mass, propellant, thrust, pitch, gimbal, turn rate, apoapsis, periapsis.

Physics & model

• Orbital mechanics — Two-body problem, vis-viva, Kepler. Symplectic Euler integration.
• Atmosphere — US Standard Atmosphere 1976, 7 layers, geopotential altitude.
• Drag — Velocity-relative, Mach-dependent drag coefficient (subsonic → transonic → supersonic → hypersonic).
• Rocket — Falcon 9–like: two stages, variable thrust (SL/vac), variable Isp, gimbal dynamics.

Guidance (Guided launch)

Closed-loop, priority-based. In atmosphere: vertical ascent → gravity turn, Max-Q protection, turn-rate limits. In vacuum: raise apoapsis, keep periapsis safe, circularize at target altitude.

For more detail, see the project README on (a star would be appreciated if you like it!) GitHub.

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