How could suction and thrusters help a car grip and launch?

Air presses on every surface, about 10 newtons on each square centimeter at sea level. A fan under a sealed skirt pulls air from beneath the car. Now the pressure underneath is lower than the pressure on top.

That difference, multiplied by the area, is a force pressing the car down. Small differences add up. Lower the pressure by 1% under an illustrative 4 m² floor, and air pushes down with about 4,000 newtons. That is roughly the weight of 400 kg.

Why does pressing down help? A tire’s grip grows with how hard it is pressed onto the road. More push means more friction for braking, cornering and launching. Unlike a wing, a fan works even when the car stands still.

Not the air behind it. A thruster forces gas out of a nozzle, and the gas pushes back on the thruster. NASA Glenn’s rocket principles use a balloon to show it: air rushes out one way, and the balloon flies the other.

That push is thrust, and it needs no traction. A cold-gas thruster releases stored compressed gas instead of burning fuel, so it pushes only while the gas lasts.

Where a force acts matters as much as how strong it is. A push in line with the car’s center of mass speeds it up without turning it. Move the same push off that line, and it also creates torque, a twisting effect that starts rotation.

OpenStax University Physics writes torque as τ = r × F: force times its lever arm. A thruster mounted low would try to lift the nose. Mounted high, it would try to tip the car forward.

The car’s own weight twists back only while its tires touch the road or a ramp. There, the car lifts its nose by pivoting on its rear tires. Weight pulls down through the center of mass, ahead of that pivot, and holds the nose down. The low thruster’s twist must beat that to start a tip. Once airborne, the car turns about its center of mass. Weight acts right through that point, so it adds no twist to beat.

Beating weight starts a tip, but it does not guarantee a flip. Twist multiplied by how long it lasts, the angular impulse, sets how much spin builds. A car with more rotational inertia turns more slowly for the same impulse. Counter-thrust can slow or stop the turn, and the flip still has to end in a landing. This is a generic teaching example, not a description of Tesla hardware.

1. Pressure

   Press a suction cup onto a smooth tile and pull. Outside air holds it on. Lift one edge with a fingernail, and it lets go.

2. Thrust

   Blow up a balloon and let it go. Air rushes out backward, and the balloon shoots forward with nothing behind it to push on.

3. Torque

   Push a book across a table through its middle, and it slides straight. Push the same way near one corner, and it turns.

Rocket Nozzle Lab, by Ryan Sael, takes thrust further. Change the nozzle’s throat, the throttle and the surroundings to see how hot gas becomes a push.

Suction needs a seal. The skirt must stay close to a surface so outside air cannot rush in. Over a bump, a ramp lip or a jump, the seal breaks and the hold fades. Once the car leaves the ground, there is no surface left to pull against.

Thrust keeps working in the air, but only while the gas lasts. Every number on this page is a generic illustration. Claims about the Roadster are Tesla’s, and we have not tested them.