Quote:
Originally Posted by Vman455
I wouldn't make a blanket statement like that; Hucho would probably say, "It depends on your goals and stipulations." Here's an excerpt from "The Aerodynamic Drag of Cars: Current Understanding, Unresolved Problems, and Future Prospects" (W-H Hucho, in Aerodynamic Drag Mechanisms of Bluff Bodies and Road Vehicles, Plenum Press 1978, pp. 32-34):
"A front spoiler reduces the velocity through the underbody region. Velocity profiles underneath a car which have been measured by Kramer et al. and which are reproduced in Fig. 28 clearly indicate this effect. By reducing the velocity adjacent to the extremely rough underside surface, the friction drag of the underbody region is reduced. If the front spoiler is properly matched to the car, this drag reduction can overcompensate for the additional drag originating from the spoiler itself.
Additionally, a front spoiler causes a reduction in pressure on the front underbody panel, see Fig. 29, and under the engine compartment's hood. The latter effect is welcome when the engine-cooling air flow has to be increased. In general, these reductions in pressure help to reduce the front-axle lift. In Fig. 30 the results from an actual spoiler optimization are compiled. The height of the spoiler is increased in steps. Very often, but not in the present example, if lowest drag is desired, a shorter spoiler results than when maximum lift reduction is the target."
I'll see if I can post the figures when I get home.
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The Jetta already embodies the 'ideal' nose Hucho tested when he ran the wind tunnel.The airdam would already be optimized.
It was Hucho that said that contemporary cars of the 1980s already had good enough forebodies,and that by definition,the purpose of streamlining was to reduce or eliminate flow separation at the back of the vehicle,and it's attendant pressure drag.I was just loosely quoting him.And I contextualized my comment by saying 'meaningful' drag reduction,which cannot be accomplished without aft-body modifications,specifically boat-tailing.
Belly and wheels would allow a a more quality flow to the rear,a prerequisite for full benefit.