Quote:
Originally Posted by Bicycle Bob
Could all this discussion of fineness ratios be resolved by differentiating between the most efficient way to move a given cross-section through the air (with no crosswind) vs the most efficient way to move a given Volume through the air? Airfoils, of course, are most concerned with moving a given surface area.
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The car guys always defer to 'drag-factor',or,CdA.And Cds are always in the context of frontal projected area.
Since most modders aren't going to chop the roof off their car or do extreme alterations to frontal area,we've kinda defaulted to drag coefficient as the thing of primary interest.
Jaray got the whole 'Streamlined body of revolution in ground reflection' going back in 1922.
Jaray,Kamm,Lay,and so many others ended up using the body of revolution as their starting point,it seems like the convention with road vehicles.
Hucho used it at Volkswagen and he's the one who cited the L/D 2.5:1 Streamline form,or elliptical form as the 'minimum' for drag.
He chastised Mercedes_Benz for not honoring it with R&D of their C-111 III.
I've been looking for anything which demonstrated the lowest Cd with minimum structure and so far,for something in ground-effect,which cannot benefit from the jet pumping action of a body in free-flight,I've never come across anything "shorter" than L/D 2.5,which would translate to a vehicle with Length,5X it's height.
Al's closing gotta go,will pickup tomorrow.