Landracing Forum
Tech Information => Aerodynamics => Topic started by: av8ford on September 05, 2012, 08:05:06 PM
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I'm not new to LSR racing nor new to motorcycle racing. I am new to LSR motorcycle racing, however, and have tons of questions, one of which I've expressed on another thread about rear suspension. So far, the responses there, pro and con, are about evenly mixed.
I'm looking for the wherewithal to calculate the CD of my proposed plot, a very low APS configuration parked behind a '92 Honda RS125 road-race fairing whose area calculates, roughly, to 4.5 sq-ft. The front wheel and forks are a bit "dirty," but I'm using the correct factory front fender to clean up that area a bit. In my preliminary design, I'm looking at a longish wheelbase that will put the rider well down behind the windscreen with backside about level with the top of a faired tail over the rear tire (in contrast to the normal road-race plot where the rider becomes an aero element above the top of the windscreen).
I don't anticipate a quick and easy answer, although that would be a pleasant surprise; I am willing to do my homework and provide any additional information that may be required.
Mike Bishop
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There are two ways to do this:
Wind tunnel and if you are close enough A2 in NC is the place to go. They are on here time to time under the aero section.
Other way is coast down testing which can give you rolling as well as aero drag coefficients. Try here:
http://www.precisionautoresearch.com/RDP/RDP_Samples/Aero-Forces.xls#CoastDown!A1
Tells you how to do it and an excel spreadsheet for the calcs.