Apoapsis

A 3D rocket-flight and orbital-mechanics simulator that runs in your browser. Build from four rockets (Sounding, Orbital, Heavy, MunShip), fly the ascent by hand or with the autopilot, then work the orbit:

Prograde and retrograde burns, maneuver nodes, Hohmann transfers, and a landing on the Mun.

The physics is real, not scripted. Thrust, Isp, and staging follow the Tsiolkovsky rocket equation, drag depends on altitude and dynamic pressure, and the equations of motion are integrated every tick. The map view shows your live orbit, periapsis and apoapsis, and the Mun's sphere of influence.

Controls: W/S throttle, A/D pitch, Q/E yaw, Space to stage, 0-9 for SAS modes, M for map, L for autopilot.

Rocket Equation: The Δv math behind the sim is at https://pe-calc.com/tools/tsiolkovsky-rocket-equation.html