John, there are some basic rules I've learned about this.
1) It's easy to poke a hole in air.
2) It's almost impossible to CLEANLY un-poke the hole.
(Look at the front and back of a 747.)
3) Once you poke a hole, if you try to change the hole you can't win.
The best you can do is break even.
4) Moving air takes energy. The energy comes from ambient air pressure
or the car.
And I couldn't agree more with mayf. Especially frontal area.
Each square inch is VERY, VERY important on a streamliner.
It's very difficult and time consuming to build a small car.
It's easier to build a bigger car and buy zillion HP pro built
motors.
Jack goes 250 MPH with less than 250 HP. Ron Main went faster,
but I bet Main spent more on gaskets than Jack did on the
whole motor. I'm serious.
Just my opinion John,
Bryan
john robinson wrote:
>
> Howdy,
> One of the questions I have is about the Red Head , if you know
> the car, it was swoopy, kinda exaggerated coke bottle Corvette shape. I was
> wondering about the drag behind the wheel humps, if it would go up due to
> turbulence and flow separation behind the hump?
>
> At 04:10 PM 11/5/01, you wrote:
> >John, I assume you wanted a real answer to you question and not just chit
> >chat. First keep the car on the ground, allow very little space for air to
> >get under the car. Air under the car has to be sheared because the air is
> >attached to the car and the ground. This eats up quite a bit of power. Next,
> >smooth swoopy corners are better than rectangular ones. Rectanglear set up
> >bad air flow problems causing drag from interference of the various flows.
> >Next minimize the frontal area. Do everything you can to reduce it because
> >it is a direct multiplier for power required ( double the area, double the
> >power at any given speed). If you can reduce the frontal area by making the
> >body lower between the wqheels, it is a good thing to do, as along as the
> >panel intersections are not angular corners. Given all that, I wouldn't be
> >doing a front driver. Asking the tire contact patch to do to many things:
> >forward traction, steering, etc. Anyhoo, good luck...send me a jpg when it
> >looks good...
> >
> >mayf
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