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

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.
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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