Raptor Engine Anatomy

Raptor engine anatomy

SpaceX's full-flow staged combustion engine, as a 3D assembly you can take apart and a flattened 2D schematic that shows how propellant flows. Selecting a part in either view highlights it in both.

Propellants CH₄ + LOXCycle full-flow staged combustionChamber pressure ~350 bar (Raptor 3)Thrust ~280 tf (Raptor 3, sea level)

3D assembly

Drag to orbit, scroll or pinch to zoom. Click any part to select it, then use Isolate to see it alone or the X-ray slider to look through everything around it. The geometry is a proportional, representative model: SpaceX hasn't published Raptor's detailed plumbing, so pipe routes and valve positions show where things connect, not exact CAD.

Combustion chamber
Drag to orbit · right-drag to pan
100%
0%
Raptor engine schematic Methane and oxygen pumps, two preburners driving two turbines, a gas-gas injector, regeneratively cooled chamber and nozzle, gimbal and steering actuator. Gimbal TVC actuator Fuel pump Turbine LOX pump Turbine Fuel-rich preburner Ox-rich preburner Main injector CH₄ in LOX in Combustion chamber Throat Nozzle Cooling jacket Exhaust ~3.3 km/s

Why the nozzle doesn't melt

The gas in the chamber is around 3,500 K. Copper alloys melt near 1,350 K. The wall survives because heat is pulled out of it faster than the flame can push it in.

Cross-section of the chamber wall Hot gas ~3,500 K Film Copper liner Methane channels Steel jacket Heat flows right, into cold methane. Methane flows along the channels, then on to the preburner.

Not to scale. The liner is only a few millimetres thick, which is the point: a thin, highly conductive wall can't build up much heat.

1

Regenerative cooling

Cryogenic methane runs through hundreds of small channels milled into the chamber and nozzle wall before it is burned. The fuel soaks up the heat, and that heat isn't wasted: it warms the methane on its way to the preburner.

2

Film cooling

The injector sprays extra fuel along the inside of the wall. It forms a cooler boundary layer so the hottest gas never touches the metal directly.

3

Copper that conducts fast

The liner is a copper alloy. Copper moves heat so quickly that the hot face stays close to the coolant temperature on the other side. A steel jacket outside carries the pressure loads.

The throat is the hardest spot: the gas is densest and fastest there, so heat flux peaks. Cooling channels are packed tightest around it.

Design your own Raptor

Every control below is a free design variable; everything else is computed from them. It starts at Raptor 3's published sea-level figures. Choose whether you set the thrust and let the throat size follow, or set the throat and let the thrust follow. You can't set both: they are tied together by chamber pressure.

Force at the ambient pressure below. The throat is resized to deliver it.
The narrowest point of the nozzle. It sets how much gas can get out.
Higher means a smaller engine for the same thrust, but more pump power and heat.
Kilograms of oxygen per kilogram of methane. Stoichiometric is ~4.0; engines run fuel-rich for cooler, lighter exhaust.
Exit area ÷ throat area. Bigger bells win in vacuum but separate at sea level.
Pressure lost in cooling channels, preburners, turbines and injector. More losses, more pump power.

How the variables connect

You set thisComputedAffected by what you're touching

Thrust from sea level to vacuum

Nozzle to scale

Model: ideal 1-D nozzle flow with a fixed γ = 1.2, curve-fitted methane/oxygen combustion data, and a 99% nozzle efficiency. It is tuned to Raptor 3's published 250 tf, 330 bar, O/F 3.6 and expansion ratio 34.3, and lands near the family's ~327 s sea-level Isp. Pump power and heat load are rough estimates, good for trends rather than absolute values.