n_anirudh wrote:Idea would be to change damper settings to adjust the ride height in the wind tunnel, and do a parameter study to find DF vs. ride height. (considering the change in fuel load as well over the course of race distance)
Mapping those parameters and then set the ride height to a given range. The variation curve might still resemble a normal distribution curve..
maybe I am stating the obvious here..looking forward to more opinions..
the tire guru's when pressed will admit the same problem exists with tire data, the nice smooth force vs slip curves are a result of massive data reduction and assumptions
stolenmojo wrote:you've tripped over a big problem with aero testing in general here - regardless of scale of testing. typically you articulate the model to a given position and hold there for a certain set time to collect samples of data from the balance and then smooth that data for a result. you do this for multiple heave, pitch, yaw, and roll positions to build an aeromap. there's big assumptions and data reduction involved and this always leads to opinions.
obviously air isn't that well behaved and there's significant dynamic issues when the position of the car is varying. it's difficult to quantify in a test, it's difficult to study in cfd and it's one of the hidden attributes that can make a gain in car design not show up in lap time. one method is to study the derivative of aero loads between two positions - in an ideal car you would drive this to zero for constant aero load regardless of position. pitch sensitivity gets thrown around a lot and that's simply the derivative wrt pitch change, but what about roll or yaw as well. F1 race engineers try to make this a minimal effect by running bare minimum wheel travels in their setups but the tires (tyres) move a lot more than the torsion bars do and you can't change that much.
the tire guru's when pressed will admit the same problem exists with tire data, the nice smooth force vs slip curves are a result of massive data reduction and assumptions.
scarbs wrote:I recall listening to a Racetech Symposium lecture by RUAG (http://www.ruag.com/en/Aviation/Innovation/Wind_Tunnel) who did some work on dynamic ride height measurements, with a Porsche sportscar IIRC. Like all things with aero, the more you try recreate real life situations, the harder you make life for yourself. Not surprisingly they found the lift curve differed for the same ride height depending curve depending if ride height was raising or lowering, as I recall this was still at low frequencies, the high frequency we saw on the McLaren at Silverstone must produce some very strange aero effects.
See page three http://www.ruag.com/de/Aviation/Innovat ... _Emmen.pdf
May be the next step for F1 teams is to run a full lap aero simulation based on real-time chassis attitudes, much like they do for the chassis on a four\seven post rig.
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