Teams protest McLaren's rear wing

If I understand the dynamics of a "Blown Wing" the air flow over the wing isn't effected as much as the interaction between the flow of air and the wing surface. It's a method of stalling the wing without changing the wings angle of attack.

I think it's a given that within the next 3 months, every car on the grid will be fitted with a similar system.
For those of us who didn't major in fluid dynamics here's a nice simple explanation of how and why a wing stalls and, to some extent, explains why you would want to do it on an F1 car.

Renault aren't happy: McLaren legality 'a complete joke' - Renault

Renault technical director Bob Bell has slammed the FIA's decision to allow McLaren's innovative rear wing.
"It is a complete joke," he told BBC Sport. "It has driven a horse and cart straight through the rule that teams cannot use moveable aerodynamic devices on their cars. It is fundamentally illegally. At a time when we are trying to cut costs, this will just start a new arms race. The FIA have acted irresponsibly. It's going to cost everybody a lot of money. The governing body needs to be a lot stronger with these things.
By "moveable aerodynamic devices" he presumably means the driver's knee?
He's wrong of course, although he could use the Renault Mass Damper ruling as a precedent...

Perhaps it's time to change the wording to 'variable-input aerodynamic device'?

One other thing - Most reports are concentrating on the funnel on top of the leg area. Now, I'm no scientist or aerodynamics expert, nor am I an employee of McLaren, but wouldn't they be getting more air to the wingflap from the air into the airbox? Clearly they can't stop/allow this flow with their knee, as is the suggestion with the funnel, but with the funnel one blocked off, you'd still be getting the blown wing effect from the airbox when cornering, which would reduce the benefit, no?

Part of me is thinking the funnel is a decoy :dunno:
Thanks Snowy, that explains quite a bit. So the driver's leg/knee is acting as a valve, changing the airflow from the airbox to the wing/below the wing.

1) It looks legal
2) It's very clever
3) How much has been spent to gain just a few kph on the straight?

It has now emerged from comments by Martin Whitmarsh to that McLaren do indeed have a link between their rear wing and the snorkel on the top of the chassis. While a link between the two parts emerged during testing as they were both fitted with the same aero testing set up, it is only now that the full picture has emerged. Using the driver to interact with the snorkel feeding the rear wing and its attendant slot, the wing can ’stall’ increasing straightline speed when the driver needs it.

How its done…

The snorkel on the top of the chassis feeds a duct passing down inside the footwell, its position is some where around the pedals, most probably it runs down alongside the brake pedal\footrest so as to avoid the mandatory padding inside the cockpit. This duct has a ‘hole’ in it to ‘cool’ the driver inside the cockpit. However the duct continues inside the chassis, past the fuel tank and up and over the airbox (probably passing by the hatch fitted high up on the engine cover), then through the shark fin and into the rear wing flap.

When the driver places his foot\leg over the ‘hole’ the flow is diverted into the rest of the duct and this feeds the slot on the rear wing flap. There is enough airflow through the convoluted duct to disrupt the airflow under the rear of the wing, effectively breaking up the flow around the wing. This is what F1 aerodynamicists term a ’stalled’ condition, although this is different to the term ’stall’ used in aeronautical aerodynamics. In this ’stalled’ state, the strong spiralling flows coming off the wing, that lead to the huge drag penalty a highly loaded F1 wing incurs, break up. With out these flows and their resulting drag penalty, the car is able to get to a higher top speed, by around 3-4kph.

When the driver is ready to brake for the next corner, he releases foot\leg and the airflow passes back into the cockpit and the rear wing flow reattaches, creating downforce and its attendant drag. In this format the car can lap normally with its wings delivering maximum downforce.

This set up is legal as the rear wing slot in itself is legal (used by McLaren, BMW Sauber last year). There is no specific working to prevent wing stalling in the rules. There are no moving aerodynamic parts, except perhaps for the drivers foot\leg. It’s a piece of interpretive genius, but perhaps as far removed from the spirit of the rules as you can get.

What now

Of course now its deemed legal, teams can either formally protest it or adopt it themselves. Doing the the latter is possible for most teams, as they have apertures in the footwell area to fit a snorkel, while the shark fin and rear wing are easily created. But, finding a route for the duct out of the tub might prove the headache, as the monocoque may not have any openings sufficiently large enough. This year the monocoque is also is subject to homologation and hence cannot be altered until the 2011 season. Of course ‘where there’s a will, there’s a way’, teams will not want to lose a straight line speed advantage.
Thanks people! Especially the vid from FB and the last link/quote from Snowy. I now understand it!* :)
For a non-techno type person like me, this is quite an achievement! :)

I was watching the practice today, feeling baffled by the comments about stalling. Now though, I'm a de-facto stalling expert*.

* Amendment - I mostly understand it, from a layman's point of view. If you asked me to make a working model to demonstrate this, I'd fall flat on my face!
Another season of gang up on McLaren and its not even the first race yet.

At one time when one team developed a technical advantage, come the next grand prix the other top teams would have developed their own take on it.

Now it seems that there's a lot of finger pointing and cries of 'cheat'.
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