Landracing Forum
Tech Information => Aerodynamics => Topic started by: Jack Gifford on April 18, 2019, 01:35:08 AM
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To heck with wind tunnels. Let's just spend some time up on Mt. Washington, where the record wind velocity is two-hundred-thirty-something MPH. :roll:
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You guys haven't forgotten Woody, have you? He can do a few things with CFD you can not get from a wind tunnel. I benefitted greatly from the Darko tunnel but given the closest one (A2) is now over 1200 miles from me (in the wrong direction from Bonneville), cost of towing, meals, hotel and tunnel fees are far greater than what Woody charges.
John
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It took me twelve years to develop a good shape by trial and error, book learning, and finally wind tunnel testing. Pretty much all of the records are now unobtainable in the classes the bike can run. My method is not recommended. It takes too long.
There were conversations with expert racers during those years with some listening on my part. This is what I would do if I did it again. First would be to use a laser printer or similar to make a scale model of the bike. One of those GI Joe dolls would be dressed up to resemble me. The bike would be scaled to match the doll.
The bike with doll on it would be wanded to make a digital model. Virtual aerodynamics would be used to analyze the shape and this would be done as many times as needed to make it optimum. Then the bike with doll would be sent back east for tunnel testing. Finally the bike would be made and the final tunnel testing done with me in the seat.
This is a heck of a lot less work than the way I did it and much faster.
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Coast down times and a pocket calculator tell you the combined rolling and aero drag . 2 wooden models on a parallelogram linkage mounted ahead of a car would tell which is aerodynamically better .
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Only problem with coast down is it doesn't point to where you need to make changes. But absent a full scale wind tunnel or Woody's CFD services, coast down is OK to test comparative changes that affect Cd.
John
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You guys haven't forgotten Woody, have you? He can do a few things with CFD you can not get from a wind tunnel. I benefitted greatly from the Darko tunnel but given the closest one (A2) is now over 1200 miles from me (in the wrong direction from Bonneville), cost of towing, meals, hotel and tunnel fees are far greater than what Woody charges.
John
In the 1960s, Chrysler did some scale model testing at the Wichita State University wind tunnel. I don't know much about that tunnel but I'm sure that it is still operational. Since it must close to you it's worth a look.
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Wichita State has several wind tunnels... One was big enough for a 50cc Motorcycle sidecar.. but it had to be lowered in with crane thru a panel in the ceiling... they are designed to be aircraft and airfoil model testing tunnels.
If you had a model and could convince a class that it would be a great croup project you might have a chance. Ross and I talked to a guy that will be a senior next year.... he said he would pitch a motorcycle project to his classmates...
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If you guys are into scale model, there's a place in Indianapolis. Moving ground too!
If anyone is looking for serious consultation on this stuff message me.
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Who is it in Indy?
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Auto Research Center. Used to be Reynard North America many years ago. They still have a moving ground scale tunnel, 7 post shaker rig and gearbox dyno. They also have their own version of the cfd software open foam (which in one form or another is industry standard now) as well as their own computer clusters to run it on.
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https://jalopnik.com/the-ford-f-250-trunnel-is-for-those-who-want-to-do-aero-1842492987