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Old 05-06-2009, 06:53 PM   #7 (permalink)
aerohead
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low Cds

Ernie,I'm not sure what "category" of vehicle you're interested in.Subaru and GM have developed windtunnel models with Cd0.088 at critical Reynolds Number.Honda took GM's Sunraycer and did the mods Aerovironment knew about,but did not do,to push Cd0.12 down to Cd0.10 with their Dream-2 solar racer.--------- The twin-boom Tarf race car is rated at Cd0.10There is a university-sponsored mileage marathon car claiming around Cd 0.089 or something like that,but this is below critical Reynolds Number and is of dubious value to us,unless we're willing to drive at or below 20 mph.------- Many Bonneville streamliners have forms in Cd0.11-0.12 range( Goldenrod,Pumpkin seed,Ken Lyon's BMW 'liner).------ Ford's PROBE-V concept car was "producible",with Cd0.137.----------- The old-school theoretical limit for a vehicle on the road,in ground-effect,and above critical Reynolds Number is Cd0.10 (like Dream-2).The mileage-marathoner Cd claims may be a bit disingenuous do to their remarkably low velocities .These numbers need to be taken in a proper context.All these cars are "passive".Perhaps "active" aerodynamic cars will evolve with dynamic morphing abilities which can push the envelope a bit.We'll have to see.That's all I have off the top of my head.Good luck with the project,it sounds interesting.If you have access to "Enviromentality" Sierra Club of Dallas' cable-access television series,there are a couple of episodes I did back in the early 90s on aero.Around May/June 1991.
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