Quote:
Originally Posted by hat_man
Sorry for a confusing title but my simple mind couldn't figure out a better wording.
I guess what I am wondering about is, is it (to an extent) as beneficial to direct airflow unattached as it is attached?
The example I am seeing is this. We know an aerpcap on a pick up it the best for aero. Airflow stays attached and is "shaped" for lack of a better term. But the cab spoiler/half tonneau is rather close in benefit, but seems unattached so that flow is maybe more "influenced".
If this is the case, then could the same principle apply to say the underbody of the same pickup. Rather than a full belly pan (attached or "shaped") but rather a fin arrangement, directing or "influencing" the flow outward as opposed to directly under.
We know that an air dam is the way to go, so this isn't a real world application. Just a mental exercise I guess so I can try and learn something.
Thanks for any insight.
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1) The 'wing/ half-tonneau' values you quote are only for a circa-1988, half-ton, Ford F-150, long-bed, of Cd 0.535, and 31.6-sq-ft frontal area.
2) Any later evolution of the F-150, or other legacy maker 1/2-ton would be an unknown quantity.
3) The 2012 F-150 received Brett Herndon's patented 'Aerolid' and it registered a delta Cd 0.067.
4) We have no wing / half-tonneau data for that truck.
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5) As to the underbody, no one has officially tested a specific truck, back-to-back, comparing the difference between an airdam, and full belly pan with diffuser.
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6) Successful operation of a 'fin' is predicated upon 'clean' air. Clean air does not exist downstream of an airdam. Clean air would only exist along a proper belly pan.
7) There would be some clean air 'below' the elevation of the airdam, although fins would add frontal area, drag, and interference drag, not appreciably improving anything, as they cannot undo the damage from the turbulence 'above.'