Rivals feverishly working to copy F-duct

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Days before the first Grand Prix of the season, McLaren's MP4/25 grew an air inlet on top of the chassis. It turned out to be a feeder for its F-duct system. An air channel is contructed through the chassis, along the driver's legs and through the shark fin into the rear wing. By carefully controlling the airflow with his knee, the driver can now cause the rear wing to stall, allowing up to 10km/h advantage on a straight.

When Jenson or Lewis put their knee onto the channel, they force the airflow to continue through the car and sharkfin and to exit on the rear side of the rear wing. This additional airflow disrupts the laminar flow along the underside of the rear wing, causing it to detach and effectively stalling the rear wing. This process momentarily reduces rear downforce and drag until the driver releases his knee and allows the air into the cockpit again.

As the system is obviously efficient, Sauber has already introduced their own version, while Red Bull Racing and the Scuderia have declared to be looking into a solution. Renault said 7 days ago it wasn't going to develop a similar system, but they might just have to if they want to keep up with the quick boys.


By one_o_six on 15-04-2010 at 12:26

Hi, Given the system is operated by the driver, having a opening/closing device, shouldn’t it be considered a moving aerodynamic device, and thus be illegal?
I remember Renault passive shock absorbers being banned, for having been considered moving aerodynamic devices. Regards, J

By keener427 on 16-04-2010 at 04:13

The ingenuity of the solution is the drivers knee is rumored to cover a hole to effect the stall. There is nothing in the car that moves at all, the only moving part is the drivers knee. While genius given the wording of the rules against tuneable aero, it does certainly seem to go against the spirit. Since it appears to be allowed it will be interesting to see the other solutions given the tub is already set, McLaren designed theirs in from the start. Can't wait to see how the others compare...

By mx_tifoso on 16-04-2010 at 07:23

I fail to see how someone can effectively and safely cover the hole while racing and sustaining frequent 3-5 g's in multiple ways; corners, acceleration, braking.

By Herr_Koos on 16-04-2010 at 13:01


Read the article again. The drivers cover the hole to stall the wing, thus they only have to do this while on the straights. The rest of the time they sit in a normal position.

By manchild on 17-04-2010 at 00:00

Stalling of wing would reduce downforce but increase turbulence in the same time. So, the benefits could only come from increased ride height on straights as it would enable air to flow more easily under the car's floor, thus increasing ride height trough limiting functionality of the diffuser.

However, I'm not convinced that it's the way it works.

I think those systems are completely passive, and that driver has no control at all. F-ducts are so small that they get choked at high straight speeds all by themselves. By my opinion, F-ducts feed the wing to produce more downforce, and once car reaches close to top speed at straight, they choke thus reducing downforce. Basicaly, that would enable teams to run rear wing on slightly lower angle than teams with no F-duct, which considers less drag with identical downforce level apart from straight.

By mx_tifoso on 17-04-2010 at 04:21

Thank you, Herr Koos.

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