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Old 03-22-2016, 05:48 PM   #55 (permalink)
aerohead
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without tires

Quote:
Originally Posted by gumby79 View Post
Just called darko they said :
"A full size pickup is to large for our tunnel as well as A2 wee have the same tunnel. The only tunnel that i know of that is large enoughfor an full size PU is Lockheed Martin in Atlanta Georgia for $3,000 per hour. This is ware GM took their production vehicles for Aero testing until they built their own WindTunnel. Darko test cell is 13'x9' " He asked for pics to do some math and figure out , if we take the wheels / tires off and put it on blocks , if it will fit. He said they have a 5000lbs limits per axel . He estimated 3-4 hr @500usd
Aerohead: if it fits without tires will this negate the reliability of the test?
Freebeard: the accuracy of a creek or stream would not be available the flow speed and volume is constantly changing and would negate any results as a steady speed could not be maintained this is why I was going the route of trying to get a model tested in a water channel where controlled conditions exist. But a good idea
*Yeah,without the wheels we'd have no clue as to what was going on.
*Tesla claims that the wheels on their S model contribute 20% of the overall drag.
*Hucho reported up to a 50% drag increase when wheels were added to low drag bodies.Here you can see what happened to Buchheim et al.' model at VW's tunnel

*Even if we had a wheels-off baseline on your truck,we wouldn't necessarily know if that relationship would hold as your streamlining brought the drag down.
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CAR and DRIVER used to do fee testing which included SAE-protocol coastdowns at the Chrysler Proving Grounds near Ann Arbor,Michigan.They tested my Honda back in 1991 for $500.Since Csaba Csere left as Technical Editor,I'm unsure if any of the current staff are even acquainted with the procedure.C&D hasn't included coastdown data since the 1990s.
It wouldn't hurt to call them or email.They'd also do top speed on the Chrysler oval test track and we DO have a drag relationship for this where we could reverse-engineer drag coefficients.Gearing can be an issue though,as basically all USA vehicles are using gears are a speed governor.
*Forget about Bonneville.The rolling resistance is so high,and the 1-mile track to short to allow for terminal velocity.You'd never make it to top speed.
*I don't even think that the 2-mile at Mojave Airport,California is long enough.
*El Mirage Dry Lake isn't any better,and we have rolling resistance issues there as well.
*we amateurs have a tough time getting lab quality data.
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Last edited by aerohead; 03-22-2016 at 05:53 PM.. Reason: add data
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