Tommy Cookers wrote:I've done some checking .........
at AoAs beyond max Lift Coefficient ('Stall') the Drag Coefficient rises rapidly and continually (with AoA)
similarly the LC falls continually but much more slowly
Unfortunately you checked for something which is pretty irrelevant for the discussion at hand.
There is no stall mechanism due to increased AoA in the F1 wing case, so this comparison to an aircraft regime is pretty mood.
As you increase AoA on a flat plate/barn door or wing, you change the form(drag) of this object, quite significantly, which
adds for the increase in drag.
There is a reason that aircraft wings get tested for drag at zero lift.
So, if you look for anything remotely wing related, you would look for a wing at or close to max lift position and then see what happens, to lift and drag when you increase velocity (freesteam).
No change of AoA comes into play in the F-duct / VD wing example.
DRS is a different matter, because you change the form/shape frontal area of the wing, is closer to reducing flaps on a aircraft after take off etc. But I think any direct comparisons to aircraft's operational conditions will not bring us much further, because they are just to different.
An aircraft, does not have any "need" to produce excess lift in level flight, it just needs to produce enough upwards force (lift) to overcome it's own mass (weight) to not "fall out of the sky".
I read an interview yesterday, in which one of the Sauber engineers said, that there car is optimized (aerodynamics) to ~200 km/h, which I would take as to say, that they have there best L/D at this speed.
Anyway, a couple of years ago, it was quite "in fashion" to "........." a wing (make it shed drag & downforce) by letting the upper element (flap) bend under load and close the gap, between the main plane and the flap.
If this technique would have been counterproductive, then I doubt that the FIA would have stepped in to mandate the slotgap separators, which are mandatory now.
On a slightly related note, some F3000 teams used to mount the beam wing upside down in Monza couple of years ago, and found a increase in top speed, during a test. ( due to the rules, you could not run without wings/flaps/beam wings etc., you had to have them on the cars in one of the predefined positions).
FIA did not like it too much, and issued a bulletin, saying that cars running this during the following race weekend would be excluded - one team was later excluded after the race for this.
Just look at the formula for induced drag on a wing, that pretty much gives you the answer:
As you increase lift, you increase drag, all other things being the same
The total drag coefficient is equal to the drag coefficient at zero lift (Cdo), plus the induced drag coefficient.
Cd = Cd0 + Cl^2 / ( pi * Ar * e)
As normal cars, don't normally generate large amounts of lift or downforce, Cdi is often ignored, and Cd is only made up from Form/Pressure drag and skin frictional drag etc.
But for and F1 or race car which produces large amounts of downforce it can't (should not be ignored)
Now on a "normal"/fixed wing, to increase Cl you increase AoA, until the critical AoA, but if you find a way to increase Cl
by other means (CC wing etc.) you still have the dependency of Cdi from Cl even if you take AoA out of the picture.
Don't get fouled by diagrams like this:
which seem to show, that induced drag reduces with speed, while form drag and parasitic drag increases with speed.
This diagram, shows the contributions of the different forms of drag, on a operational aircraft under normal operational conditions. And because the aircraft has no need/use for any excess lift, it will reduce Cl from the wings as it flights faster.
Because it is not concerned with Cl, it only needs Lift (a force) to maintain level flight, as it fly's faster a given wing with a given Cl will produce more lift (force), but also more drag.
Because the extra lift (force) is not needed (in level flight) the pilot will try to reduce Cl from the wing, and by doing so, he reduces induced drag as well.
But this has nothing to do with a F1 car at increasing speeds, where AoA does not change and where the Cl of the wing is more or less fixed.
Furthermore, they , want to produce "excessive" lift/downforce as faster as they go ,until they come onto the straights.
Last edited by gato azul on Mon Aug 13, 2012 5:17 pm, edited 2 times in total.