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Flight & control · Interactive Simulation

Cold-Gas Car Flight Simulator

Tank pressure · Thrust authority · Landing reserve

Tesla flew a Roadster on cold-gas thrusters on 15 October 2026. The obvious question — how long can it actually stay up — has a calculable answer, and it is not the one the tank capacity suggests.

Interactive simulation Every assumption is an input No registration Runs in your browser

Climbs through 7 m and rolls once about its long axis, as Tesla showed it, in a 10 m/s crosswind — then catches itself and lands.

600L

Reported as 200 L in the Thrust trim, with a further 400 L in place of the second seat.

690bar

10,000 psi is the figure in circulation. At that pressure air is about half as dense as the ideal gas law would claim.

20mm

One of four, at the corners of the floor. 20 mm gives about five times the car's weight on a full tank — the class of the 80 kN reported for the launch. Narrower nozzles run out of authority sooner; wider ones draw the tank further down.

1700kg

Without the air. Reported as under 1,700 kg.

10.0m

How high it climbs — or, in the roll, where it starts to turn over. Every metre is paid for twice.

Advanced parameters4
27°C

A warm fill stores less air in the same bottle.

70s

Cold air through a well-shaped nozzle at 300 K. It falls with the square root of temperature as the tank chills.

0.00m

How far forward the centre of mass sits. The mixer has to trim it out with uneven valves.

5m/s

Steady, from the left, across the car. The waist pair of attitude ports holds it sideways; past about 20 m/s they are flat out and the car leans into the rest.

Ready

Pneumatic system

TANK A TANK B — bar · — °C · — kg MANIFOLD — kg/s FL —% — kN FR —% — kN RL —% — kN RR —% — kN LIFT · — kN each wide open NOSE — · —% WAIST · SIDEWAYS — · —% TAIL — · —% ATTITUDE · — kN each wide open · side push — kN 4 MAIN THRUSTERS · SHUT — not used in a hover ⋈ solenoid valve · fill = average duty · dashes move with the flow
  • —mAltitude
  • —sFlight time
  • —barTank pressure
  • —kgAir remaining
  • —°CTank temperature
  • —kNThrust
  • —Thrust / weight
  • —Available / weight
  • —kg/sMass flow
  • —sSpecific impulse
  • —°Tilt
  • —mDrift from the pad
  • —°Roll, counted round

This is a model, not a specification. Tesla has published no figures for the system, so every number below is an input with a stated default — change one and the flight changes with it.

Try this

  1. Run Hop with a roll and watch the roll counter go round 360°. Upside down, every newton the lift nozzles make pushes the car at the ground — which is why the roll starts while it is still climbing.
  2. Run Fly until it falls and watch the two bars from 12 m. The air bar still has a third left when the margin crosses 1 and the car stops flying.
  3. Narrow the lift nozzles from 20 mm to 16 mm and run the 10 m hop. The tank still has air, but at the bottom the nozzles no longer have the pressure to brake with.
  4. Set the crosswind to 12 m/s, then 25. At 12 the waist port facing you fires and the car stays level; at 25 it is flat out and the car leans into the wind.

What is on the machine

  1. Two COPV tanksComposite-overwrapped vessels lying fore and aft, 600 litres between them at 690 bar — about 267 kg of air, not the 480 kg the ideal gas law would promise. Both feed one manifold, and both frost over as they empty.
  2. Four lift nozzlesAt the corners of the floor, in the overhangs clear of the wheels, exhaust down. Between them they carry lift, roll and pitch — the same three jobs a quadrotor's four rotors share. These are the ones the model fires, and their positions are the arms the mixer uses.
  3. Four main thrustersIn a row across the diffuser, exhaust aft, fed by one header behind the tail. They are what the car launches on; in a hover they do nothing, and the model keeps them shut.
  4. Six attitude thrustersAround the body. The pair at the nose is the only authority the car has about the vertical axis — four downward jets cannot turn it. The model fires that pair and leaves the rest dark.
  5. Suction fans and skirtsFour fans in the floor pull the air out from under it while skirts seal the edge against the road — downforce for cornering, at a standstill as well as at speed. Drawn because it is on the car; it takes no part in a flight and the model leaves it off.
  6. Solenoid valvesOn or shut, never in between, and never open for less than 8 ms. The demand is banked and spent in pulses, which is why the bars chatter.
  7. Inertial unitAttitude and rates for the loops. The model assumes it is perfect — real noise and lag would cost margin, and that is a demo of its own.
  8. Landing padMarked at 3.4 and 4.7 m. The drift reading is the distance from its centre, which is what the position loop works to keep at zero.

What this model computes

The physics
behind the picture

The model is a rigid body with ten working nozzles: four at the corners of the floor for lift, roll and pitch, and six attitude ports in three pairs — the waist pair to push the car sideways, the nose and tail pairs firing against each other to turn it. Thrust comes from choked flow through each throat, so it follows tank pressure directly.

The tank is the part most back-of-envelope answers get wrong. At 690 bar air is not an ideal gas — the ideal law would promise twice the air the bottle holds. The model uses the Abel–Noble equation of state, which puts 600 litres at 267 kg, and empties the tank isentropically, so it cools as it drains.

That cooling is why the flight ends early. Thrust falls with pressure, and pressure falls faster than mass does. The car loses the ability to hold itself up with a third of its air still on board.

The roll is a moving target handed to the attitude loop: a reference that turns about the car's long axis on a smooth schedule, its rate and acceleration fed forward so the loop only corrects what the schedule did not predict. Thrust is eased off while the car is upside down, because there every newton the lift nozzles make pushes it at the ground.

The autopilot is the cascade a multirotor flies, with a reaction-control system added: a position loop that decides where the car should go, side ports that take the sideways part of that first, an attitude loop that delivers the lean for the rest, a least-squares mixer that shares the work across four nozzles, and pulse-frequency modulation because solenoid valves cannot be throttled.

Tank pressure, volumes, nozzle placement and vehicle mass are taken from press coverage of the 15 October 2026 demonstration. Tesla has published no specification; nothing here is a claim about the vehicle. Figures from Electrek — a technical look at the next-gen Roadster.

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