[ODE] [off-topic] Modelling aerodynamics

[Nate W]

On Tue, 10 Dec 2002, Thomas Harte wrote:

> I looked it up, apparently the correct formula to work out the aerodynamic drag on a 
> vehicle is :
> 
> Fd = 0.5*rho*Cd*A*V^2
> 
> Lift is then defined, using the same variables as :
> 
> Cl = 0.5*rho*Cl*A*V^2

Also note that Cd and Cl will change as the car's local airspeed vector
changes.  In other words, the Cd and Cl for a car rolling forward will be
different for a car sliding sideways.  

The relationships are probably nontrivial, but you could probably fake it
reasonably well. :-)  My earlier suggestion of using vector projection
might be more trouble than it's worth...  But basically I think you'll be
in the ballpark if you figure Cd and Cl for both forward and sideways
motion, and use a simple method to "scale" them for the vehicle's
orientation (e.g. vector projection or sin & cos or even just linear
functions), and sum the results.  Probably be good to do the same for
backward travel travel, in case your players spin out. :-)

-- 

Nate Waddoups
Redmond WA USA
http://www.natew.com