Abstract
A way of making an estimate of the drag area is to model the car as a composite of shape elements which have known drag coefficients. The drag areas of these shape elements are added to give the drag area of the car at a particular speed. This is called the drag build-up method.
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Notes
- 1.
Page 14−3
- 2.
As previously explained: a measure of the goodness of the fit, with 1.0 indicating an exact fit.
- 3.
Fortunately, solar racing cars can take advantage of some options that passenger cars usually cannot. Solar racing cars can use wheels with smaller thickness-to-diameter ratios, and thus smaller drag areas. They can partially enclose the wheels in streamlined fairings or in nearly-sealed wheel housings.
- 4.
The flow would be symmetric with respect to a centered single wheel.
- 5.
The drag coefficient passes through a maximum at β≈ 15° (not shown).
- 6.
Pershing and Maskai also point out that such items may be located in regions of accelerated or locally-separated flow. This will change their drag contributions.
- 7.
The angle of attack is the angle between the chord line and the relative wind.
- 8.
According to Morelli (1983), most automobiles lie between clearance ratios of 0.05 and 0.2.
- 9.
DF was calculated over the laminar and turbulent regions (x = 0 to xC and xC to L, respectively). The results were added and (17.17) applied.
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Thacher, E. (2015). The Drag Build-up Method. In: A Solar Car Primer. Springer, Cham. https://doi.org/10.1007/978-3-319-17494-5_17
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