alt 0.0 km
v 0 m/s
a 0.0 g
Ready — press Launch
A side-view multi-stage rocket ascent that is genuinely computed, not animated: real mass depletion from thrust and specific impulse, altitude-varying gravity and atmospheric drag, and real staging that jettisons dead structural mass mid-flight. A live Tsiolkovsky delta-v budget tracks the ideal speed each stage should deliver against what the numerical integrator actually achieves once gravity and drag losses are subtracted, alongside a live altitude/velocity trace of the whole climb.
This is a real numerical rocket-ascent integrator, not a scripted animation. Every frame, it computes thrust, current vehicle mass, altitude-varying gravity and atmospheric drag, then integrates F = ma forward in small substeps — the same way an actual trajectory solver would, just simplified to one dimension (straight up). The multi-stage Tsiolkovsky delta-v budget it displays is calculated properly, including every stage still stacked above the one currently burning.
Real mass depletion (ṁ = thrust / (I_sp·g₀)), real staging (dead structural mass is jettisoned the instant a stage's tank empties), gravity that weakens with altitude, and drag from an exponential atmosphere. A live graph traces altitude and velocity as the flight unfolds.
Pick a preset or set your own vehicle: specific impulse, stage wet mass, propellant fraction, thrust per stage, number of stages and payload mass. Press Launch, then Pause/Resume; Reset restarts with the current design.
The "achieved Δv" readout is smaller than the "ideal Δv" from the Tsiolkovsky equation for every real flight — the gap is exactly the gravity and drag loss accumulated while the engines were firing, typically 1–2 km/s for a real orbital launch.
Nothing here is precomputed or interpolated. Each simulated frame recalculates the vehicle's current mass from how much propellant has actually burned, then integrates Newton's second law with real gravity and drag terms to get the next velocity and altitude. The flight path is a genuine output of that integration.
Ideal Δv comes straight from the Tsiolkovsky rocket equation applied to each stage's mass ratio — it is the delta-v you'd get in a vacuum with no gravity to fight. Achieved Δv is what the physics integrator actually delivers once gravity (pulling down the whole burn) and aerodynamic drag are subtracted in real time.
Each stage carries its own propellant and dry (structural) mass. As soon as a stage's propellant reaches zero, its dry mass is jettisoned from the vehicle's total mass and the next stage ignites — visible on screen as the rocket getting visually shorter and a piece of debris falling away.
Newton's law of gravitation falls off with the square of distance from Earth's center: g(h) = g₀·(R⊕/(R⊕+h))². At a few hundred kilometres up this is a small but real effect, included here so the physics stays consistent rather than assuming a constant g all the way to orbit.
No — a real orbital insertion needs most of its delta-v sideways to achieve orbital velocity, not vertical altitude. This simulator simplifies to a 1D vertical climb so the mass, thrust and staging physics stay clear and controllable; it uses the commonly cited ~9.4 km/s delta-v figure as a stand-in target for "orbit-capable," not a literal vertical trajectory to orbit.