The Physics Behind Tesla's Flying Roadster 2 Prototype

Tesla's Roadster 2 prototype, unveiled by Elon Musk last week, can drive up a vertical wall, leap over the company's vehicle lineup, and accelerate from 0 to 60 mph in under a second. Its wall-climbing trick works by using fans and side flaps to lower air pressure beneath the car, mimicking a vacuum cleaner and boosting the normal force that generates friction. With a target weight of 1,700 kilograms and roughly 2 square meters of contact area, the required underbody pressure comes to about 86 percent of atmospheric pressure. A conventional car limited by a rubber-on-asphalt friction coefficient of 0.6 tops out at an incline of about 31 degrees, or 42 degrees at a coefficient of 0.9. The same suction improves right-side-up performance by increasing frictional force for faster acceleration, braking, and sharper turns. For its sub-one-second sprint, the Roadster 2 fires compressed air out the back, relying on Newton's third law much as a balloon-propelled toy car does. Its brief airborne hops use the same compressed-air thrust, though tank pressure drops quickly. Video analysis of the jump over a roughly 4-meter-tall Tesla Semi yields an estimated vertical acceleration near 98 meters per second squared, about 10 g's, which humans can survive briefly but not comfortably. A robot, not a person, was behind the wheel for that demo.