FoxHound wrote:But I have to repeat, I still see no evidence to suggest that Rake will not create more drag at speed.
There are five different diffusers (or angles) plotted on the graph, and they're represented by curves that depict downforce coefficient as a function of both increasing ride height and decreasing ride height.FoxHound wrote:There's a tidy explanation which still points to higher rake meaning higher drag. I dunno if we going round in circles yet, but it does seem this point has not been surmounted.
Maximising the downforce of the diffuser is, however, a subtle issue. The downforce generated by a diffuser is a function of two variables: (i) the angle of the diffuser, and (ii) the height above the ground. Generally speaking, the peak downforce of the diffuser increases with the angle of the diffuser. Then, for a fixed diffuser angle, the downforce generated will increase according to an exponential curve as the height reduces, until a first critical point is reached (see diagram above, taken from Ground Effect Aerodynamics of Race Cars, Zhang, Toet and Zerihan, Applied Mechanics Reviews, January 2006, Vol 59, pp33-49). As the height is reduced further, the downforce will increase again, but according to a linear slope, until a second critical point is reached, after which the downforce falls off a cliff.
In line with your tidy explanation, please identify the diffusers (or angles) for which any deviation from optimal ride height - indicated by their respective points of peak downforce - results in an increased downforce coefficient, thus an increased drag coefficient.

And yes, we're definitely chasing our tails here.
