Quote:
Originally Posted by ennored
Something in that series of "buses" doesn't add up.
.88 Cd to .36 by just rounding the front? That doesn't agree with other known Cd's I've seen (NASA and others).
I think the claims of an Airstream being about 30% better than a "normal" trailer are probably close, some from a better Cd, and some from a smaller frontal area. Which is also in the same ballpark as one of the NASA studies where they rounded the front of a boxtruck. 30% better than .88 is .62, way off .36.
Which is all just speculation. No real wind tunnel tests = no real number. Seems like there isn't one out there.
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*I don't have Hucho's book with me.I'll go back and check the numbers.
*Hucho's model has a smooth belly,something NASA's Econoline did not until later.
*Hucho's model had no 'features drag',(cut lines,gaps,ridges,laps,wheel-flop area ),and cooling system.
*Hucho's model had a larger fineness ratio that NASA's van.
*Hucho's model had full wheel covers.
*Hucho's model was @ zero-yaw,compared to some crosswind at Edward's AFB secondary runway.
*Hucho's softened,and boat-tailed model is in good agreement with NASA's belly-panned,boat tailed Cd 0.238.