How much is a "point" of downforce?

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raymondu999
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Joined: 04 Feb 2010, 07:31

Re: How much is a "point" of downforce?

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From Pat Symonds' tech column in F1 Racing magazine:
Pat Symonds wrote:When engineers refer to points of downforce, what do they mean?
When we discuss downforce or drag, we try to normalise results so that ambient conditions are irrelevant. If we simply talked about how many newtons of downforce were produced at, say, 200mph, this would vary between a hot day when air density is low, and a cool day when air density is high. Aircraft pilots know about this and adjust take-off speeds depending on ambient conditions as the lift their craft experiences also varies with temperature and air pressure.

To eliminate this ambiguity, we express downforce by means of a term we name the "lift coefficient." Of course, since it is downforce we are interested in, the number is negative. This coefficient is a number that, when multiplied by air density and the square of the speed as well as a reference area, will tell us the actual downforce. The reference area is generally the frontal area of the car but, although many teams express this as 1.5 square metres, there is no hard and fast rule and so the way one team expresses the lift coefficient may be slightly different to another.

Let's say a car has a lift coefficient of -3.50. The gains made in the windtunnel will often be of a magnitude shown only by the second decimal place of that coefficient and, for convenience, aerodynamicsists talk about this being a point. Therefore if we improved our downforce by one point we would increase the coefficient from -3.50 to -3.51. In fact, downforce gains are so hard to come by that we often use the third decimal place as well and this increment is termed a "unit."

So a point is really nothing?
It's true that it is a small percentage and the effect of a gain of one point will vary from circuit to circuit, but, as a rule of thumb, a gain of three points will represent a lap-time improvement of 0.1 seconds. Given how close racing is these days, that can be very significant.
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F1aero
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Re: How much is a "point" of downforce?

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Typically around 8lbs/point for a current F1 car

marcush.
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Re: How much is a "point" of downforce?

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Rules of thumb can be very misleading .....a gain in downforce is usualy also a gain in Drag....so as You Win You lose as well.its easy to crank on a few degrees of angle of attack, no?
WHO Said More is always better? There is always convergeance .this is why in Monza You do not run Monaco style wings.

shelly
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Re: How much is a "point" of downforce?

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F1aero wrote:Typically around 8lbs/point for a current F1 car
At what speed? 60 m/s?
twitter: @armchair_aero

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raymondu999
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Re: How much is a "point" of downforce?

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marcush. wrote:WHO Said More is always better? There is always convergeance .this is why in Monza You do not run Monaco style wings.
More downforce is always better. The added drag is a different matter. I get what you're saying - but when viewed in isolation, added downforce is always a plus
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F1aero
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Re: How much is a "point" of downforce?

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shelly wrote:
F1aero wrote:Typically around 8lbs/point for a current F1 car
At what speed? 60 m/s?[/quote

Teams will run a series of run sequences in the tunnel, be it different air vel, yaw, ride height etc.

Which leads on to
raymondu999 wrote:
marcush. wrote:WHO Said More is always better? There is always convergeance .this is why in Monza You do not run Monaco style wings.
More downforce is always better. The added drag is a different matter. I get what you're saying - but when viewed in isolation, added downforce is always a plus
This will produce some values which will take into account a rebalanced figure against drag ect.

So an aero device is not "better" if it produces more Cl and creates more drag giving a lower rebalanced value

shelly
shelly
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Re: How much is a "point" of downforce?

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@F1aero: do you confirm that for most teams 1 point = 0,01 S*CL?
twitter: @armchair_aero

bobby
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Re: How much is a "point" of downforce?

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https://www.f1technical.net/features/21963

is as good an explanation as anything else.

In other words a point/unit is only relative for any given speed, but fir F1 will be measured at/for the wind tunnel Vmax. Generally anything less than 1 point (10 units) is not worth putting into production for f/size.
There's usually be a couple of screens collecting data from a number of ride-heights, say >15, which come through on rolling/dynamic spreadsheet.

And if a team is lucky, a couple of aero bods who atcually understand what they're looking at...

garygph
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Re: How much is a "point" of downforce?

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Is Shelly around anymore?