Yahoo Autos Gordon Murray's McLaren F1 Successor Uses a Fan for Downforce and Drag Reduction
Gordon Murray, designer of the McLaren F1, is hard at work on a successor to the iconic supercar. Called the T.50, this concept revives the F1's signature delta-formation three-seater layout, with power from a new 3.9-liter naturally aspirated Cosworth V-12 producing 650 hp and revving to an outrageous 12,100 rpm. And for his next ultimate road car, Murray is revisiting one of his most extraordinary aerodynamic concepts.
In 1978, Murray designed the Brabham BT46B Formula 1 car. You know it as the "Fan Car," for the huge fan coming off the rear of the car, driven by the gearbox, which evacuated air from under the car to create a vacuum, sucking the car to the track surface. It only competed in a single race; after a dominant showing at the 1978 Swedish Grand Prix, Brabham pulled the car so as not to create a political firestorm with other teams.
"The Brabham fan car that everybody sort of knows... is quite a blunt instrument really," Murray told Road & Track over the phone. "Very effective when it's raced, but not really practical on a road car, and to be really blunt, too crude."
As you can see in the images here—the first renderings officially released by Gordon Murray Automotive—the T.50 has a rear-mounted fan like the BT46B. But it's a much more refined item. The T.50's fan is electric, which allows for infinitely variable speed, something the Brabham was not capable of.
Murray said that the fan on the T.50 is used for boundary layer control, managing the airflow above and beneath the car. "As designers and aerodynamicists, we'd all love to have very steep, aggressive diffusers at the back of the car to expand the air, and therefore, accelerate the air underneath and get more ground effect," he explained. "Unfortunately, air has a mind of its own, and it'll only follow a certain profile before it stalls and breaks away from the surface and causes a vortex, or a series of vortices."
We've done the ideal, very steep, aggressive, diffuser... We have strategically-placed slots in that surface," he said. "What we do when the fan fires up, and we want more downforce at lower speeds, is we open the slots and spool the fan up to maximum, and we remove all the dirty air and the boundary layer, and that means that the air has to follow the surface. It's forced to follow the surface to fill the vacuum that was left there."
The T.50 will have six aerodynamic modes. Automatic mode adjusts fan speed and the two flaps on either side of the fan in real time; Braking mode deploys the aerofoils and uses the fan to increase downforce. Murray claims that stopping distances from 150 mph are 33 feet shorter in this mode.
