I was going to do a bit of number chrunching, and the thought occured to me, how much downforce is there on a modern F-1 car? How much drag?
I realize that it varies from circuit to circuit, but I'm looking for some 'ballparks'
This is what I have so far...
Frontal Area...
The old 2 metre width gave a frontal area of approx 1.5 square metres. The new 1.8 m width gives about 1.35-1.4 square metres. (my figuring out of FIA min dimensions...)
Downforce...
From McBeath's Downforce book... 'At 200 mph on a high speed circuit (low drag) approaching 4000 lb (in 1996 cars)'
Equates to a CL of over -2.3
Ummmm.... Isn't that a bit high for a low downforce circuit?
From a racetech interview with Eghbal Hamidy (then with Arrows)....
Q: 'How much Downforce?'
EH: 'The cars are now generating the same level of downforce as in 1996'
Q: 'At 150 mph in Monaco trim, just over 3000 lbs? At Monza 2200? At Silverstone 2700?'
EH: 'If anyone has those figures they would be going very fast. They are very optimistic figures.'
From Katz's Race Car Aerodynamics...
Generic 1983 F-1 car CL -0.99 (LOW! The Beginning of flat bottom cars?)
Can't find much else...
An interesting figure...
1991 Penske Pc20, High Downforce CL -3.33. Speedway -2.073.
Quite high.
Other CART figures, this time from a 2000 Reynard.
Just over 5000 lbs at 200 mph on a road course.
In Homestead/Chicago spec around 3000 lbs (no mention of velocity)
On Superspeedway, just under 2000 lbs.
Any ideas as to what are ballpark F-1 downforce figures? Was there a ajor regulation change after 1996? I know there was in 98...
How much Downforce on a modern F-1 car?
Started by
ehagar
, Jun 28 2001 18:09
8 replies to this topic
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#2
nzkarit
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Posted 28 June 2001 - 23:18
Will at 200kmh they can drive upside on the roof.
so at 200 downforce >~650kg
so at 200 downforce >~650kg
#3
Ben
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Posted 29 June 2001 - 14:40
Without really considering whether -2.3 is too high or not it's worth noting that most Cls are calculated using planform area not frontal area.
Ben
Ben
#4
ehagar
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Posted 29 June 2001 - 16:34
Originally posted by Ben
Without really considering whether -2.3 is too high or not it's worth noting that most Cls are calculated using planform area not frontal area.
Ben
On cars it is based on frontal area, on aircraft and wing sections planform area.
Anyone else have any figures?
#5
Ben
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Posted 02 July 2001 - 20:43
Race Car Vehicle Dynamics by the Millikens presents an analysis of ground effect aero and uses the planform area of the car to calculate the Cl.
You might not use planform area but the experts appear to. It's just a reference area and the Cl.A value is always more useful in my opinion.
All I'm saying is that if you use a representative planform area you might get a value for the Cl that you might find more convincing than your original estimate.
Ben
You might not use planform area but the experts appear to. It's just a reference area and the Cl.A value is always more useful in my opinion.
All I'm saying is that if you use a representative planform area you might get a value for the Cl that you might find more convincing than your original estimate.
Ben
#6
ehagar
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Posted 03 July 2001 - 05:24
Don't take this the wrong way, but I really don't care what way you use as a reference....
Yes, planform area is quite acceptable, and I've used it alot for aircraft calculations. The frontal area reference came up because I noticed that the quoted values from Katz's book are based on frontal area, and 2 other automotive downforce books also used it as standard. Since their figures are referenced in this manner, I use their convention. All It generally means that the CL valus are higher. Maybe it is because initially automotive types were only interested in drag, and never thought of wings on cars. So the most important reference would be how wide the car is, a bluff body really.
I view it as quite irrelevant really, because CL is a non-dimensional figure.To me its semantics. You could base you area on whatever you want. I assumed because of three automotive books that I have dealt with, the accepted practice was frontal area. The important part is to be able to realise when a CL is too big make sense.
In the case of McBeath's book he mentioned he was basing it on frontal area, so a figure of -2.3 really is within ballpark. What puzzled me though, was that he said at circuits such as Monza and Hockenheim... I would figure in those cases the downforce would be at a max 2300 lbs, not 4000 as he stated. I'm thinking they would be using a lower downforce set up than that, that's all. So the guy was basing it on frontal area and coming up with a number that was viewed, IMHO as high.
Yes, planform area is quite acceptable, and I've used it alot for aircraft calculations. The frontal area reference came up because I noticed that the quoted values from Katz's book are based on frontal area, and 2 other automotive downforce books also used it as standard. Since their figures are referenced in this manner, I use their convention. All It generally means that the CL valus are higher. Maybe it is because initially automotive types were only interested in drag, and never thought of wings on cars. So the most important reference would be how wide the car is, a bluff body really.
I view it as quite irrelevant really, because CL is a non-dimensional figure.To me its semantics. You could base you area on whatever you want. I assumed because of three automotive books that I have dealt with, the accepted practice was frontal area. The important part is to be able to realise when a CL is too big make sense.
In the case of McBeath's book he mentioned he was basing it on frontal area, so a figure of -2.3 really is within ballpark. What puzzled me though, was that he said at circuits such as Monza and Hockenheim... I would figure in those cases the downforce would be at a max 2300 lbs, not 4000 as he stated. I'm thinking they would be using a lower downforce set up than that, that's all. So the guy was basing it on frontal area and coming up with a number that was viewed, IMHO as high.
#7
AndersF1
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Posted 03 July 2001 - 15:59
A short, maybe unnecessary, remark:
The "typical" reference area should be choosen as the area that affects CL and CD the most, if changed. On aeroplanes it's of course the wing plane area, as that has much more effect on the lift and drag than the frontal area has. When dealing with pipe flow, the frontal(pipe diameter) area is usually used and the same goes for cars. There are of course a lot of cases when you don't know what to choose, like for a F1-car maybe, but the main thing is to use the same for all comparisons and preferably the "typical" reference area, if there is one. I guess the frontal area is used in F1 due to the resemblance of cars.
When you look at old F1:s, like 30 years and more ago, then I think there were no question about which area to use as the drag was much more important than the lift, but nowadays you should maybe use wing- and also body-plane area as reference area. With increasing lift the drag will also be less dependent on the zero-drag and more dependent on the part of the drag that is approximately proportional to the square of the lift, the lift induced drag.
The "typical" reference area should be choosen as the area that affects CL and CD the most, if changed. On aeroplanes it's of course the wing plane area, as that has much more effect on the lift and drag than the frontal area has. When dealing with pipe flow, the frontal(pipe diameter) area is usually used and the same goes for cars. There are of course a lot of cases when you don't know what to choose, like for a F1-car maybe, but the main thing is to use the same for all comparisons and preferably the "typical" reference area, if there is one. I guess the frontal area is used in F1 due to the resemblance of cars.
When you look at old F1:s, like 30 years and more ago, then I think there were no question about which area to use as the drag was much more important than the lift, but nowadays you should maybe use wing- and also body-plane area as reference area. With increasing lift the drag will also be less dependent on the zero-drag and more dependent on the part of the drag that is approximately proportional to the square of the lift, the lift induced drag.
#8
ehagar
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Posted 03 July 2001 - 20:44
Kind of what I was getting at I guess. Drag ws more important in the old days with cars. With road cars, drag is still the most important consideration for reduced fuel economy (well, I guess considering the number truck and SUV's maybe not...). Hence the bluff body analysis in he automotive books I guess.
It really doesn't make any difference, because it just changes you coefficient of lift. The problem is, if you don't know what the reference is. Using frontal areas the CL is quite higher than A/C CL's
No biggy. But back to my original question.
About what downforce values do F1 cars get. 2200 @ 200 mph @ Monza? 3000 at 150 mph @ Monaco? 2700 lbs @ 150 at Silverstone?
It really doesn't make any difference, because it just changes you coefficient of lift. The problem is, if you don't know what the reference is. Using frontal areas the CL is quite higher than A/C CL's
No biggy. But back to my original question.
About what downforce values do F1 cars get. 2200 @ 200 mph @ Monza? 3000 at 150 mph @ Monaco? 2700 lbs @ 150 at Silverstone?
#9
The Rock
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Posted 06 July 2001 - 18:24
i heard some where that an F1 car produces some much downforce its possible to drive the car up side say going through a tunnell at speeds around 190mph.
