Some simuv2 aerodynamics questions

Dear folks,

I've been browsing aero.cpp in simuv2 (CVS torcs), and I've seen a couple 
of things that intrigue me, so maybe you'll be able to provide some 
answers. Please keep in mind that my knowledge in aero is pretty limited. 
Also, book and article references would be appreciated too.

1) I've got some mix-and-match in the units side. The code seems to be 
working mostly with SI units. However, the xml files have milimetres, 
imperial (springs) and some others. Is there any list of what isn't SI in 
the code? I'm basically doubting ride_height.

2) Drag due to yaw =/=0 seems not implemented. See line 87. How much this 
affects drifting? Would it be worth to run a couple of tests adding the 
lateral area of the car into account or would I be wasting my time?

3) On line 87, the drag reduction due to slipstreaming (dragK) is squared. 
Is there any easy explanation for that?

4) Christos explains in his site that ground effect goes like
       F_i= C_i*v²*exp(-b*h)
It struck me to see ride height fully averaged instead of "axis averaged". 
Is this intended for ease-of-setup? (balance is thus fully determined by 
front and rear Clift).

5) The actual ground effect formula seems to have the average height at the 
fourth power. This differs from what is stated here, 
http://www.idiap.ch/~dimitrak/torcs/carsetup.html but, again, simuv2 is 
supposed to provide four times too much downforce. Is this the cause?

6) Wing efficiency L/D = wing->Kz / wing->Kx is 4.0. Is this high? Low? 
I've been googling a short time, and the closest I've seen is a L/D list of 
airplane wings and birds in wikipedia, and 4 is on the low side.

Finally, I'm sure all of you have noticed how even small amount of damage 
has a large impact in laptimes in fast ovals and e-track 4, while one can 
lap within 1 second or so in e-track 1 and g-track 2 and the other slow 
tracks with damage upwards of 2000. Would it be very silly to implement a 
bodywork downforce penalty similar to the drag penalty? The most obvious 
effect I see is that robots might be penalised by not accounting for 
downforce correctly.

Thanks a lot for your answers and your patiente if you made it this far. 
Regards,

Miguel

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