Reducing the drag of a two element wing through stall

[Giblet]

Well cupidstunt, you like many in this thread seem to be thinking in extremes. The wing I think does not stall completely, it becomes less effective at speed.

If the knee does control the wing, then the moment he brakes (left side snorkel), his knee is off the 'valve' and the wing becomes it's usual strong self. Any driver worth their salt in F1 uses left foot braking. Even Rubens had to convert from his heel toe happiness.

It makes sense in that way, that the moment you want to brake, you want the wing 'on'.

I don't think the wing stalls out completely. If the rear wing is say 10 clicks, maybe it just acts like a 9 click wing at whatever speed it is at. Not enough to send the car into a huge spin. The rear wing is 1/3rd of the downforce, diffuser 1/3rd, front wing 1/3rd and drivers are constantly adjusting the throttle anwyays for slight changes in grip all the time.

If it is a corner that might be too dangerous to risk a knee coming unlodged, they just don't activate it.

[cupidstunt]

I'm still not buying it. I don't think you can convince me that with g-forces and all the other things a driver has to do in the car, they can use it reliably. Surely if they were learning to use this new device, then there would have been a lot of mishaps in testing. I don't remember hearing about Mclarens spinning off a great deal.

Even a 10% decrease in downforce as you suggest is a big deal when you're on the edges of grip surely?

[hollus]

No strong G forces, no split second decisions, no precission needed and virtually no penalty for missing the spot in a straight. If the key element is, say, above the knee, it is perfectly safe, your foot is either at the brake pedal or off it, and we don't hear "I accidentally released the pedal in that corner"...
I am one of the main followers of all this stall (partial!) theory and I still can't get around of how bizarre it is to put the control device more than two meters away from the rear wing. But it is possible and I won't discard it, and in that case, one of the reasons would be driver control.
Cooling, I also find it unlikely and extremely complicated for the function.
Cockpit aerodynamics, possible, but how much air can run through it?
Maybe it is for something completely different that we have no idea about, and maybe it is just a funny decoy.
Imagine it, come bahrain, the FIA unveils its "snorkel camera", and its function is to optimize light conditions for it

Let the season begin! Please!!! [-o<

[bidong]

=D>

it has been a funny winter testing thread with all this knee jerking (both puns intended.) i just dont buy the knee valve shmalve theory/speculation. The cockpit has too little space for lateral leg movement. you can just push and pull, no left and right. The FIA has made sure the cockpit was tight, for safety reasons. Closing a hole while driving an f1 in a straight where there are intense vibrations? i just dont buy it. it feels too farfetched and seems like an aerodynamicist's dream.

I believe that the third hidden rear wing element/slot produces negative lift (up-force in the formula one car) to control wing efficiency at high speed.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Has anyone here discussed the hole behind the drivers helmet? What's a possible difference in function with the one for the engine intake?

[cupidstunt]

your foot is either at the brake pedal or off it, and we don't hear "I accidentally released the pedal in that corner"...

Are you really suggesting that the wing should only be at full strength while breaking? I definately don't buy that! What happens when the driver releases the break and is still going round the corner/starting to apply power?

Serious mid corner oversteer/going backwards would ensue.

[Pup]

I think his point is that the drivers don't seem to have a problem performing a myriad of other tasks during the race.

[Shaddock]

If we assume the switch stalls/partially stalls the rear wing and reduces drag and DF then drivers will enter the braking zone with less overall DF than they would have with a regular rear wing. However, they will still have downforce, just perhaps 20% less at the rear until there speed drops below the threshold level.

As the car slows DF levels drop off anyway, and the driver has to modulate his pressure on the brake pedal. What this might mean in practice, is the driver winds his brake bias forward slightly on a long straight to compensate for reduced DF at the rear.

He will loose some braking performance but the front wing is still giving 100% to the front tires, and this is where most of the braking forces takes place. This is a compromise – but what you gain in top speed should out weigh what you loose in braking.

[Pup]

I may be wrong, but it seems that the cars generate excess downforce for the end-of-straight turns anyway. That is, it's rare to see them lock up the brakes immediately. Locking usually occurs at the end of the braking zone, where they are trying to feather the brakes as downforce comes off. Or am I being selective in my memory?

[simoncm]

Verdict: SLC is the better aero engineer, but simoncm is a far better artist.

I'm not really sure what's going on in this diagram! I'm assuming it is attempting to depict the load vectors, but I'm not entirely sure simoncm has them clear in his head.

SLC, I think the biggest difference between our diagrams (apart from the artistic merit, thanks Pup ) is that you are treating the wings as a single entity, with one set of force vectors, while I am trying to separate the wings.

We could debate the merits of my approach, but I think it serves its purpose. That is to show why a stalled wing (bad in aeroplane terms) is good in F1 terms. In particular, the right hand images are identical to the left hand ones (copy paste etc...), just rotated and inverted and with the forward wing removed so that the remaining, rearward wing looks more like an aeroplane wing.

For clarity, here's an updated image with the drag included in both scenarios.
.

The arrows are force vectors, and show the lift of the wing (vertical in the aeroplane pictures) and the drag of the wing (horizontal in the aeroplane pictures).

When these force vectors are rotated along with the wing to provide the left hand, F1 pictures, it can seen that the the overall force in the rearward direction has reduced for the F1 car, despite the drag of the rearward wing increasing. This is mainly due to the loss of lift from the rearward wing which has a component which extends in the rearward direction. (Which is basically the same point you made with your MS Paint drawing).

Of course, my force vectors are pure guesses. There are all sorts of subtle changes which would occur if you stall a fixed wing by altering the blowing (as I believe we are assuming McL are doing).

[autogyro]

It does not need a drivers knee to have a control flow of air that negates the slot effect at a set speed.
Just an adjustable intake for the control flow that can be adjusted during stops by the driver.
I wonder if Schumaker got the Merc one sorted at Rockingham?

[ISLAMATRON]

There is a whole in the nose of the 25 right there.

And all you guys shooting down the knee switch idea have never used an air switch in a hot tub... same principle... use the left knee because it does nothing going down the straight and the driver will get off the "switch" when they go for the brakes. And using the driver would be the only legal way of having a "switch"

Not saying that is definatly what is going on, but it is a plausable idea.

[Giblet]

your foot is either at the brake pedal or off it, and we don't hear "I accidentally released the pedal in that corner"...

Are you really suggesting that the wing should only be at full strength while breaking? I definately don't buy that! What happens when the driver releases the break and is still going round the corner/starting to apply power?

Serious mid corner oversteer/going backwards would ensue.

I think the suggestion is more like the driver can have it on or off whenever he feels like it, but at the end of a straight, when he lifts the throttle and hits the brake, and possibly removes his knee from the alleged knee hole.

[Just_a_fan]

And all you guys shooting down the knee switch idea have never used an air switch in a hot tub...

And all you guys (and me as well, sadly) have never driven an F1 car at 180mph+ with our arses an inch off the ground. Every little ripple in the track is transmitted to the driver and could easily lead to his knee moving on and off the "switch" which might have interesting effects on the rear wing's performance.

I walked around Silverstone with Justin Wilson (when he was racing with Minardi). As we walked around Maggotts, he commented about a really viscious bump near the apex which meant one had to be very precise with the car's position to avoid a big jolt. "What bump?" I asked, looking at the smooth tarmac. The reply was along the lines of "Trust me, at 180mph the slightest ripple feels like a pothole in these things".

[ISLAMATRON]

You obviously dont know the level of bumping going on in hot tubs

if they turn all those knobs and switches with "inside out" gloves and reach down and change the brake bias, a knee bump aint a big deal

[Ciro Pabón]

Well, we have to wait and see, then. Those air intakes has been used in previous models for something as prosaic as cooling the driver.

Using the body of the driver sounds a little ridiculous and I find understandable that some members dismiss the idea: please, guys, sure you can understand that idea too, even if you don't agree with it.

Please, don't look for fights in this new thread. Don't look for what you haven't lost, would say my grandaunt.