Quote:
Originally Posted by JulianEdgar
I don't understand. The K value doesn't appear to have thing to do with Cd for flat plates.
"Drag coefficients are shown as 'K', which is in lb sq feet (mph)^2"
Why aren't they talking of the frontal area of the car? ie lbs drag per square foot of frontal area * (mph)^2.
I am no mathematician but I would have thought the conversion of that to Cd would be fairly straightforward.
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Aeronautical engineers don't typically use projected frontal area-based drag coefficients.
* They may use wetted-area-based coefficients.
* They may use volumetric displacement-based coefficients.
* All components of an aircraft can be calculated individually, then added together, plus an estimated interference drag component.
* Typically, they resolve total aerodynamic drag into that of an equivalent flat plate, flat into the 'wind.'
* Sometimes they've used flat plate area sliding parallel to the streamlines, both sides.
* All calculations are for 'flight conditions,' maybe cruising at 41,000-feet altitude Above Ground Level/ Above Sea Level.
It's a nightmare!