Reducing the drag of a two element wing through stall

[bill shoe]

Thank you to everyone who has done 100+ pages of discussion on the McLaren and its wing. I've followed almost all of it. I don't have anything to add, I just appreciate the discussion.

[Blackout]

I haven't red all previous pages, sorry, but I'll will ask a (dumb) question:
Why don't they use a simple button on the steering wheel to control the air ?

[higgi91]

I haven't red all previous pages, sorry, but I'll will ask a (dumb) question:
Why don't they use a simple button on the steering wheel to control the air ?

Not dumb ...Becasue then it would be a movable device or something like that where as if the driver operated it, it is ok because he is not part of the machinery.

Woop 1st post, hi guys

Dan.

[vinuneuro]

This is good news. If Ferrari won't protest, there's a good chance it'll stick as legal.

"Ferrari sources have confirmed to AUTOSPORT that the team has no intention of taking the matter further, and have ruled out the possibility of it lodging a protest."

[volarchico]

But he has explained it. I've explained it. Others have explained it. It was explained on the 2nd post of this thread. It's explained on this very page twice.

The induced drag that is lost in a stall is greater than the form drag that is increased in stall.

There it is. That's it. That's the theory.

Not satisfied without numbers? Me either. Want to disprove it? Be my guest.

Yeah, perhaps it was explained before, but my hard-headedness would not believe something so counter-intuitive compared to aircraft aero. What I really meant to ask was the part you allude to at the end. I wanted someone to show me some numbers or some proof that the induced drag loss really is greater. That is all. I also got side-tracked in my thinking when people started indicating that the blown-slot was actually meant to create the stall. I've already said this before, but it seems more likely that when the air is flowing through the slot (from the airbox) it's keeping the flow attached. When they "flip the knee switch" the blown-slot stops blowing and the wing stalls.

[Just_a_fan]

This is good news. If Ferrari won't protest, there's a good chance it'll stick as legal.

"Ferrari sources have confirmed to AUTOSPORT that the team has no intention of taking the matter further, and have ruled out the possibility of it lodging a protest."

Maybe the FIA gave them a very quick clarification: "Hello Mr di Montezemolo, Mr Todt says 'pffff!' "

[vall]

This is good news. If Ferrari won't protest, there's a good chance it'll stick as legal.

"Ferrari sources have confirmed to AUTOSPORT that the team has no intention of taking the matter further, and have ruled out the possibility of it lodging a protest."

Maybe the FIA gave them a very quick clarification: "Hello Mr di Montezemolo, Mr Todt says 'pffff!' "

I think the wording was "asked for clarification", not protest. Sometimes they use this approach to ask if something is legal or not

[SLC]

Excuse the horrific MS Paint skills but this is effectively what is going on in terms of drag reduction (and ignore the exact magnitude, direction, centre of pressure of the load vectors, and dear god, the wing profiles, this is just an example).

IMAGE ON LEFT IS FULLY ATTACHED WING.............................................IMAGE ON RIGHT IS STALLED WING


The dispute over the McLaren wing (or the "clarifications" that whatever teams have supposedly asked the FIA about) will not be about the legality of stalling the rear wing (because this is completely legal in itself), but its about the driver control over the system (the driver effectively becomes a giant moveable aerodynamic device).

[ringo]

Another consideration is that F1 wings have gurneys on their trailing edge, low aspect raito and end plates this does have an effect vortex formation and i think the slot is addressing the Vortex street and wake behind the car.

It isn't.

The stalling does effectively change the wake, the vortices are ascociated with it.

[horse]

The dispute over the McLaren wing (or the "clarifications" that whatever teams have supposedly asked the FIA about) will not be about the legality of stalling the rear wing (because this is completely legal in itself)

I know this is off topic, but I'm surprised that the legality of stalling the wing is not in question. Wasn't that the point of introducing the spacers in order to stop this happening (or similar effect from altering the AoA)? Or was it because a flexible wing was deemed not to be strong enough? Even if this is the case, is there still a possibility that the downforce may not return to normal, say if the blowing does not turn back on, posing a danger of an accident?

[SLC]

The slot gap separators were introduced to make sure the wing elements had no degrees of freedom.

There is nothing in the tech regs which states that stalling the wing is illegal. All the FIA did was make sure the wing elements themselves were not allowed to flex as at the time this was how the teams were introducing the stall.

However, the teams may argue that the current McLaren implementation is "unsafe" as there is a degree of uncertainty/instability to the exact state of the wing at any point around the track (which might lead to a driver losing control of the car).

By the way, scarbs has posted an excellent article covering all this on his blog.

http://scarbsf1.wordpress.com/2010/03/0 ... -stalling/

This was my comment there and I'll repeat it here:

People need to stop thinking about this as a classical aerofoil example that you saw in Aero 101. This is a heavily loaded, highly cambered two element wing. The resultant load vector has a significant horizontal component which is acts as the main contributor to the drag.

This whole issue is not related to induced drag or skin friction type drag (which is my way of saying it’s not related to anything particularly fancy aero wise). 90% of a Top Rear Wing’s drag is pressure drag – or just the horizontal component of the wing’s load vector.

Stalling the wing leads to a large reduction in the resultant load vector – and this also means a large reduction in the vector’s horizontal component. Drag is reduced.

Also, if teams do complain about this to the FIA it won’t really be regarding the fact that they are stalling the wing (that, in itself, is perfectly legal – or rather, there are no rules outlawing this). What they will be questioning is the driver’s involvement in the activation of the pressure switch (almost certainly located along the left hand side of the cockpit and operated by the driver’s knee) required to control the wing’s state.

[Pup]

This whole issue is not related to induced drag or skin friction type drag (which is my way of saying it’s not related to anything particularly fancy aero wise). 90% of a Top Rear Wing’s drag is pressure drag – or just the horizontal component of the wing’s load vector.

SLC, I think your terminology might confuse some people who are using the wikipedia articles on drag to follow along. What you're calling 'pressure drag' is in fact referred to on wikipedia as 'induced drag': induced drag; and I think what you call 'induced drag' is the same as what they call 'form drag': form drag

[Pup]

I think the rules against moveable aero devices came about after some failures of early flexible wings. So yes, the rule isn't there to outlaw stalling - it's really a safety issue.

[horse]

Aye, I'm just thinking that, if SLC is correct in the process reducing lift and drag significantly, then there is an inherent danger of the effect happening at a time when DF is critical, like a fast corner. I think SLC is right, it's not illegal, but it may contravene the idea of the rules in such a way as to reduce safety, which i think needs to be looked at. If I were the FIA I would have liked McLaren to confirm it's safety, and perhaps they already have.

Semantics are difficult in this discussion, ay? Perhaps we should do a glossary?

[Pup]

If McLaren's system is designed to default to an unstalled state, then I guess I'd be comfortable with it if I were the FIA. I mean, things could still go wrong, but then there's a whole lot of things on an F1 car that can end in disaster if they go wrong.