de Laval nozzle

When that Roadster hit zero to sixty in zero point eight one seconds, it wasn't just spinning its tires.

It engaged a ten-nozzle reaction control array developed in collaboration with SpaceX's Falcon Nine rocket team.

We are talking about convergent-divergent De Laval nozzles firing pressurized cold nitrogen out of composite overwrapped pressure vessels, COPVs, at nearly seven hundred bar.

That's ten thousand pounds per square inch.

How fast is that gas moving? Argon modeled the isentropic expansion of diatomic nitrogen gas exiting those nozzles.

When high-pressure gas expands through a rocket nozzle at supersonic speeds, its temperature plummets instantly due to Joule-Thomson cooling and adiabatic blowdown.

If there is even a trace of ambient humidity in that gas, that water vapor doesn't just condense, it flash freezes into microscopic ice bullets at minus fifty degrees Celsius.

Those ice crystals instantly clog the high-speed solenoid valves and choke the de Laval nozzles.