Quote:
Originally Posted by BabyDiesel
Aerohead, what effect do you guesstimate the decklid extension had on Cd reduction? I find it odd that it was not included in the report Cd posted in post #3.
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I have no conclusions,only thoughts.A number of LSR cars have run them,and no reported findings so far.
*In Hucho's book he talked of 'saturation',at which,say,when the decklid was long 'enough',any additional length would return zero benefit.
*The extension would affect the downwash off the backlight allowing it to exit the car parallel to the ground which is preferred by some designers.
*The extension also has capping plates which could allow the device to act like a half-box cavity,which would help with pressure recovery and higher base pressure.
*The capping plates themselves move the center of pressure rearwards,helping to keep the car straight on the track.
*Also,the wake is underneath the decklid,giving a vertical force vector,which could help mitigate wheelspin which could cause a wreck at high speed.
*Finally,the improved flow would aid drag chute deployment.
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*The USFRA and SCTA don't allow drag reducing mods in non-Lakester/Streamliner classes,so it implies that the decklid mod is about safety,like the deep airdams and air fences.