pitot tubes on race cars

Louis-Alain Richard laraa at sympatico.ca
Fri Jul 23 00:18:29 EDT 2004

Louis-Alain_Richard wrote:

>>From the position of the tube, I guess its for measuring the actual 
>undisturbed air speed. The reason must be linked to the "flying Mercedes" 
>of  LeMans 1998.
>These cars took off because, after getting closer from behind to another 
>slower car, their front downforce was impaired to the point of being nil.
>I guess the driver wants to know when the air speed is way slower than 
>road speed.
Then Ado Sigal wrote:

I believe it is to confirm the trust and discrepancy shown with CFD test 
method. All three Mercedes actually flew, not when approaching the car, 
but the fast straitline crest before the down slope and facing the wind, 
all of which where extensively simulation and real time tested, and 
still flew. DF wasn't nil, if it was, the car would be still on the 
ground, it was actually a positive lift force big enough to lift the 
car, which flew quite the distance. 

Then Louis-Alain writes:


>From what I read at the moment, the problem was that the CLK-GTR was a short
wheelbase car with huge overhangs; the rear wing was so far behind the rear
axle, it's rear downforce was only balanced by the front splitter own
downforce. So in 2 occasions rear downforce would tilt the nose of the car
upward when following another car. On another occasion, the nose got light
when the car crested that little bump on the Mulsanne straight. And after
the nose is up just a little, you have a flying and flipping MB.

So I think we are both right. Don't forget that no less than 3 MB CLK-GTR
flew that year, 1 in the weeks before, 1 one the Thursday's practice and 1
during the race, each in its own circumstances. 


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