Simulation
Tesla Roadster Ramp, Roll and Landing
A 14-degree-of-freedom vehicle model of the new Tesla Roadster, extended with a lumped underbody suction system and ten cold-gas thrusters, simulating one continuous run from a standing start, up an inverted ramp, through a thruster-controlled roll in flight, to a landing absorbed by its own suspension.
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A Road Car with Flight Controls
The new Tesla Roadster carries two systems you do not find on an ordinary road car: cold-gas thrusters and a fan that evacuates the underfloor. The thrusters give it control authority with its wheels off the ground; the fan pulls it against the road with a force independent of speed. The manoeuvre simulated here uses both — up a ramp curving through 170 degrees onto an overhead deck, released inverted from the lip, rolled upright and landed on four wheels. Modelling it takes two things that rarely meet: tyres, suspension and load transfer from lap time simulation, and thrust allocation across fixed nozzles from rocket ascent.
The Vehicle Model
The car is a rigid sprung body on four independent corners with freely spinning wheels: fourteen degrees of freedom — three translations, three rotations, four suspension travels, four wheel spins. Orientation is a quaternion, since the car spends part of the run inverted, and contact comes from projecting the wheels onto a parametric surface: a road turning past vertical has no single-valued height. Tyre forces follow a combined-slip Fiala brush model, so longitudinal and lateral demand share one friction budget. Masses, spring rates and thrust capacities are assumed values sized to the published dimensions: a reconstruction, not a digital twin. The 3D model offered for download is an unofficial fan reconstruction, not affiliated with Tesla.
Suction and Thrusters
The underbody is a lumped air model rather than CFD: one plenum, a fan with 12 kPa of head and 60 m³/s of flow, and leakage that grows as the floor lifts off the deck. Rather than running flat out, the controller requests only the attachment and traction needed, against a 43 kN ceiling; the run peaks at 32 kN. Past the lip the pressure decays on its own.
Ten body-fixed nozzles share one 250 kg cold-gas tank: four rear at 20 kN each, two side at 3 kN, four under the floor at 22.5 kN. None gimbals or reverses, each valve lags its command by 25 ms, and the tank blows down adiabatically, so thrust fades as it empties and cools.
Ramp, Release and Flight
The event is one continuous forward simulation: the controls change between phases, the state carries across untouched. It starts from a standstill, on rear drive and the four rear thrusters; on the ramp, wheel torque is limited by the actual rear normal load, so the car has to hold on, not be placed on the surface. Once clear of the lip a 10 ms feedback loop takes over, allocating the requested wrench across ten non-negative throttles with attitude given priority over lift.
The car leaves the lip at 14.8 s, rotates upright in a little over a second and touches down 3.0 s later at 2.8 m/s vertical and 16.2 m/s forward, having spent about 125 kg of gas in the air. The landing is absorbed, not scripted: 27.7 kN peak corner load and 18 mm of compression.
What Makes It Worth Modelling
As control problems go this one is modest: rotating a car upright over a second of free flight is far smaller than flying a booster back to its pad. The interest is in the coupling. Gimmick or not, the thrusters and the fan each add real control authority and each bring a real limit: a tank that empties, nozzles that cannot be pointed, tyres that still have to carry the load. Those limits act on one another through the same fourteen degrees of freedom — an unusual thing to find under a road car.
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