Is downforce linear?

[raymondu999]

Hey all. Just a point of curiosity. Is downforce linear? So for example, let's say at x speed, a car generates about 1 ton of downforce. Does that mean at 2x speed, it generates 2 tons? How does it work? Thanks

[Saribro]

Downforce is related to velocity squared, IIRC. At least at racecar speeds (not sure about beyond that).

[Mystery Steve]

An airfoil's lift is related to velocity squared. An entire vehicle may be another story. It depends.

[Ogami musashi]

As far as we speak about the concept of downforce, it is effectively Velocity squared because it is an energy variation over time, on a wing, body where ever you want.

But, that principle is spoiled as soon as some velocity effects namely compressibility or heat transferts start to appear.


however on the whole for race cars we can say downforce is a function of x².

[alexbarwell]

There are rule of thumb aspects like the square-law, but remember that a wing in the ground-effect layer will have a disproportionate effect as a greater pressure differential can be derived with exponential effects as the distance from the ground diminishes. Remember the older racers with 'planks' rear wings about 4ft up in the air?

[Belatti]

Now thats a kind of "Wikipediable" question

[riff_raff]

raymondu999,

With regards to F1, I don't know of any mathematical relationship that is linear. Aero downforce is for the most part a product of the square of velocity. Other factors such as cost are cubic functions or higher (deltaV=$^3).

Aero lift, in its most simplistic terms is 1/2rhoV^2. So, all other things being equal, lift (or downforce) increases at the square of the speed.

Of course, you should take that explanation for what it's worth. I'm a mechanical guy with no aero background.

Good luck.
riff_raff

[xpensive]

Everything in aerodynamics revolves around dynamic pressure, why we should follow Belatti's advice;

http://en.wikipedia.org/wiki/Dynamic_pressure