How to create lift using the underside of your car

[aerohead]

Originally Posted by MazdaMatt

For some particular car, can anybody give an example of the speed at which rolling resistance is equal to aero drag? I know that it takes a LOT longer for my car to go from 10 to 0 than it does to go from 50 to 40.

CAR and DRIVER used to publish road horsepower,broken into aero and friction and tire losses,at 30-50,and 70-mph,for their in-depth road tests.I believe there is a descrepancy do to the optical speed sensor slung off the side of the car.I'm awaiting a return communication from C&D to see if Daytron Messteknik,makers of the speed sensor offered a correction factor.---------------------- The old rule of thumb,was that at about 50-mph,aero and RR were about the same.If I hear back from them,I'll let everyone know.

[JJW]

As someone who has owned a few cars with lift problems, I'd like to say I don't think it's a very desirable property of anything you plan on driving regularly at highway speed. Minimizing drag by shooting for zero downforce, perhaps, but with actual lift, at speed the car begins to lose traction. It also attains an unappealing "dancing" quality in the rear that generally feels unstable. In wet weather and snowy conditions it can get a bit scary, actually. If you notice, VW has had some problems with rear end lift on the new Beetle. There is a warning in the owners manual that if you have the model with the automatically deployed roof spoiler, adding any other aero devices can make the car dangerously unstable.

Also, positive lift would have a detrimental effect in relation to neutral lift. The lift is caused by drag, and so you would be trading drag for a decrease in friction. I'm willing to bet you'd find they cancel each other out. Lift isn't free after all.

[Xringer]

If the car has a high front end and low in rear, (ie; carrying a heavy load in the trunk),
it will have lift. One problem is, as you go faster, you end up with a LOT of lift..
Once those front wheels start floating along and you get hit by a cross-wind,
say hello to the EMTs..

[pablo_ottawa]

Originally Posted by trikkonceptz

The question is simple, Can we create lift by modding the underside of our vehicle? Not enough lift to flip us over, but enough lift that at certain speeds could affect the engine load thereby making our drive more efficient?

At first I was contemplating two ideas, dimpled bellypan, (Mangus effect).

Or some type of wing or spoiler built under the car or near and between the two tires to take advantage of that turbulent air.

Let hear some ideas, or just call me crazy and ignore this thread .. LOL

You're crazy lol...

To generate a relatively efficient means of lift you must have an aerofoil shape. If you look at most cars these days, they come pretty close. Either way, they all contain the same basic ingredients to create a fair amount of lift. These ingredients are to have a flat surface on the bottom and a curved surface on top. Air going over the top of the car creates a low pressure vs. the air going underneath (no change in pressure). This causes an upward force and most of our cars *DO* create a marginal amount of lift albeit nowhere nearly enough to render it airborne HOWEVER!!!!! Make any car go fast enough and it WILL take off. Have you ever driven so fast that the car began to feel very light and bouncy??? I have and it is scary. With this said, I don't think that purposely trying to create additional lift on your car would be a very good idea.

[Otto]

Sorry if this has been already discussed, as I've not read the whole thread.

That said, you'd want to generate negative (i.e., downward) lift, to keep the car firmly planted on the road, or at least reduce positive lift.

Bernoulli's principle being what it is, accelerated flow beneath the car would reduce pressure there, generating negative lift. Think of an inverted airplane wing.

Accelerated flow and reduced drag could best be done via smooth belly panels, often discussed in this forum.