Aerodynamic Aids - What a drag, What’s your drag? Options

[chris914]

Have you made changes to your 914 body or are you thinking of it?

Here are a number of computer models comparing different body modifications to the 914 and the effects that they have on the cars aerodynamic drag.

http://www.cassidy-online.com/porsche914/aerodynamic_aids

[Mikey914]

I agree, the wing must be suited for the application. In aircraft design, low speed 45-70mph the chord of the mean camber or thickness of the wing is on a curve that the slower it is effective, the thicker it will need to be. The real problem is that when lift is created (negative lift for this application) you also create Parasitic drag, now decreasing your top end speed.

If you were to use a wing it would have to be tuned specifically for the application for optimum benefit. Hence the $$$$$.

The real solution would be to have a variable camber wing that was controlled by air pressure. This would be the easiest way to regulate the mean camber. The Helio courier is an excellent example of simple application of this concept, it is low tech, yet does some really incredible things. This aircraft has slats that drop down below 55 and when the air pressure is greater than 55 they roll back, buy airpressure. This allows the aircraft a minimum speed of about 30 mph, and it can cruse at 165 mph. With the exception of the top end these are the speeds that you would be operating at, and I bet the benefit of the changing geometry at about 55mph would also benefit.


http://www.stolaircraft.com/
http://www.bush-planes.com/helio-courier.html

For what it's worth.

[chris914]

The real solution would be to have a variable camber wing that was controlled by air pressure. This would be the easiest way to regulate the mean camber. The Helio courier is an excellent example of simple application of this concept, it is low tech, yet does some really incredible things. This aircraft has slats that drop down below 55 and when the air pressure is greater than 55 they roll back, buy airpressure. This allows the aircraft a minimum speed of about 30 mph, and it can cruse at 165 mph. With the exception of the top end these are the speeds that you would be operating at, and I bet the benefit of the changing geometry at about 55mph would also benefit.

Hmm, now that might make a good fluids and controls project for the students.

[alpha434]

The real solution would be to have a variable camber wing that was controlled by air pressure. This would be the easiest way to regulate the mean camber. The Helio courier is an excellent example of simple application of this concept, it is low tech, yet does some really incredible things. This aircraft has slats that drop down below 55 and when the air pressure is greater than 55 they roll back, buy airpressure. This allows the aircraft a minimum speed of about 30 mph, and it can cruse at 165 mph. With the exception of the top end these are the speeds that you would be operating at, and I bet the benefit of the changing geometry at about 55mph would also benefit.

Hmm, now that might make a good fluids and controls project for the students.

Early race car wings were actuated by the brakes. Hit the brakes, and the wing flopped down. Let off, and the wing went straight. Easy.

Also, I have pictures of 356s in the 60s with wings mounted on the front trailing arms and tied to the body. When the suspension moved up (the wheel starts to leave the ground,) the wing exposes more surface area and holds the wheel to the ground. Easy.

[Mugs914]

Early race car wings were actuated by the brakes. Hit the brakes, and the wing flopped down. Let off, and the wing went straight. Easy.

Not quite so easy... I don't know of any that worked off of the brake. One reason is that the wing going "straight" when you let off the brake minimizes the downforce just when you need it most; right when you're trying to accelerate through the corner.

Mercedes had an air brake mounted behind the cockpit of their LeMans cars in 1955 but it was hinged at the rear and operated only as a brake and not in any kind of (intentional) downforce producing capacity. A couple of cars in the original Can-Am experimented with aero braking, but all of the ones I'm aware of used a separate panel rather than the wing itself.

The wings on the various Chaparrals were connected to a pedal on the left side of the floor where the clutch would normally be (They used an "automatic" transmission with no clutch). The driver controlled the wing using high angle for braking and cornering and flattening it out for the straights.

Most of the movable wings were connected directly to the suspension and were designed to increase angle of attack as the suspension extended, just like you described on the 356.

Sorry to go on so. One of my favorite subjects!

Also, I have pictures of 356s in the 60s with wings mounted on the front trailing arms and tied to the body. When the suspension moved up (the wheel starts to leave the ground,) the wing exposes more surface area and holds the wheel to the ground. Easy.

I'd like to see those. Post 'em!