Porsche explains what the most aerodynamic car would look like
Porsche’s clever engineers have revealed that if a car was to be built as aerodynamically efficient as possible, it would be in the shape of a teardrop.
Aerodynamic optimisation is the chief goal for automotive designers as each improvement made in this arena makes a vehicle use less energy and travel further.
“If vehicles were designed solely with this aspect in mind, they would probably have the shape of a teardrop,” said Marcel Straub, lead engineer of aerodynamics and thermal management at Porsche Engineering.
The ideal shape
The unique shape of a teardrop, round at the front and tapered at the rear, is as close to ideal as can get for a machine that still needs to transport passengers.
It allows air to flow freely around the exterior with particularly low resistance so there’s no “drag” against the direction of travel and no “wake” formed at the back.
Expressed in numbers, the teardrop has a drag coefficient (Cd) of 0.05. The lower the Cd, the lower the amount of force an external power such as wind exerts on the car’s body while moving.
The below diagram shows how the size of a wake formed behind a vehicle is influenced by its Cd value.
Practical implementation remains elusive
Although designers already know the most ideal shape for a car, it’s unfortunately quite tricky to implement.
The teardrop shell presents major challenges in terms of housing the engine, passengers, and luggage compartment, and the wheels that will need to be installed will cause turbulence and energy-sapping contours.
An “air cushion” or “magnetic levitation” might be able solve the problem, said Straub, though with the vehicle driving so close to the tarmac there’s another issue.
The shell only being a few centimetres above the surface results in a less-than-optimal airflow and to reap the true benefits of the teardrop body it would have to be suspended a few metres above the ground.
As such, “practical implementation has proved elusive so far,” said the Porsche engineer.
“Tilted horizontally, and with a Cd value of 0.03, the penguin would make for an aerodynamically optimized car paired with an unmistakable shape.”
