Quote:
Originally Posted by JulianEdgar
I am sorry, but are you seriously suggesting that wind tunnel testing of wheel drag, performed on a 1982 car without its wheels turning, is somehow relevant to modern cars?
Wind tunnels now test cars with a moving floor and spinning wheels. They do this for good reasons. I think this is probably the major reason that the research results have changed so much over the last decade or so.
The airflow patterns under a rough underside car like a 1982 Trans Am Firebird would be completely different to any modern car. The latest tech papers show that car drag can be influenced by how the wheels and under-car airflow interact.
I also note that "Index of Phil Knox Aerodynamic Seminars & Mod-data lists,under, Mod-data Lists: #7", as far as I can see, largely references material from the 1960s. As I said, old info is always interesting, but to apply it to current cars, when in fact current tech papers disagree, is in my opinion, not wise.
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*Perhaps we might establish a cut-off date for 'current' cars,before which,we'd discount published drag coefficients.
* Additionally,so as not to disrespect the best efforts of the top investigators of the day,we might re-test a sampling of specific vehicles,in rolling-road wind tunnels,and publish back-to-back results,highlighting the actual difference in drag measurements,on a case-specific basis.
*Since 'current' vehicles might include drag coefficients upwards of Cd 0.70,it would be very interesting to see drag variability associated with rotating,versus stationary wheels.
*Contemporary aerodynamicists painting with broad-brush commentaries with respect to the inferiority of non-rotating wheel drag measurements have an obligation to provide specificity.Context. It's a slap in the face otherwise.
*I reviewed an online article about the significance of the aero wheels on,I believe,the Tesla Model 3.The conclusion of the investigation would be a 'fail',historically,by SAE metrics,unless considered within a very narrow interpretation of language used by the reporter.
*Wheel drag contributions have been part of the automotive literature since 1922.Advancements and refinements in testing are a natural progression,and welcome,however, contemporary investigators may not want to inadvertently disrespect the very shoulders they stand on.It's matter of simple courtesy.