Metro aerodynamics

[Compaq888]

Originally Posted by SVOboy

I just think that the design is too prone to catching wind under it, and I have a feeling that even if it would stay flat I'd hit the off ramp or a curve in the highway and it'd go out and not stop. At 55mph it might take a piece of my fender with it.

I'm thinking of a design in my head that should work and it will open up thank to the tires but it won't do anything to it. Too bad I suck at drawing.

It involves some magnets and ball bearings.

[SVOboy]

Well draw it up then, or just do it.

[Compaq888]

Originally Posted by SVOboy

Well draw it up then, or just do it.

I'm too broke to do something of that nature. I think the materials alone will be $100 for both sides.

I'll draw it up later.

[Compaq888]

here is the design.

[Mighty Mira]

Compaq888, now THAT is a cool idea, FAR better than mine. Kudos! That's what's so great about forums, you can approach the best ideas so well because everyone can critique and improve upon each other's designs.

With some rare earth magnets (Neodymium Iron Boron (or NdFeb)), it would work perfectly. Any idea for what to use to attach the rod to the skirt? It would be best if it hooked on to the underside of the skirt, that way it wouldn't be visible. Perhaps just welding some sort of disc on top. I have drawn a diagram.


One thing you'd want to do is maximize the distance between the brackets to minimize the play in any other dimensions other than the desired axis of rotation.

Also, I was thinking that some simple rollers would work just as well as ball bearings.

The other thing is, you will want silent rollers, and you also want there to be some sort of force that either acts to return the swivelling skirt to the original position, or at least retards the motion somehow. The last thing you want is it oscillating and banging away in the wind. The magnets would work great - once the tray was remotely near them. But the effective range of magnets is very limited. So either the rod needs to be attached to the skirt with brackets that are tight enough to have a bit of friction, or there should be some sort of spring (or just a length of thin spring steel) attached to the rod to get it to want to recenter after the wheels have gone back to their original position. (Of course, this would all need to be worked out to see if these concerns are valid.)

Of course, the closer the swivelling skirt is to the wheel, the less this would be an issue.

Advantages of the swivelling skirt being close to the wheel:
1. Lower frontal area, the whole purpose of having a skirt in the first place.
2. Less room to oscillate.
3. Skirt is closer to the magnets, so that when it is near the original position, it would bite without any other force necessary.

Advantages of the swivelling skirt being further out:
1. Less use of rollers, and hence less chance of the skirt being anywhere other than aligned where it is supposed to be at speed.

I think the magnets should grabbing at around 20mm.

Unfortunately, you can still see the wheel with full skirts, so it's difficult to get away with the dubious asthetics of pizza trays. Although if you lowered the car, they would be less visible. Spray paint them a matte grey or match the color of the car, it could work better. The trouble with lowering the car is that you might damage your skirts inadvertently. The other thing is, if you already have a full undertray that minimizes drag under the car, why would you even need to bother adding in an air dam to route air somewhere else? It doesn't make sense to me. The only reason after a full undertray that you'd want to lower it would be aesthetics.

Anyway, great thinking and great work.

[GasSavers_katman]

You could attach a rod to the steering linkage and your green disk so that as you turn the wheel the disk follows. So now no rollers or magnets. This also eliminates road grim, snow, mud, etc. from causing problems with your rollers. What are you going to fill the gap in front of the tire with? This is going to be a big air scoop. However you don't turn the wheels that far at higher speeds so it might not mater.

[Mighty Mira]

Originally Posted by katman

You could attach a rod to the steering linkage and your green disk so that as you turn the wheel the disk follows. So now no rollers or magnets. This also eliminates road grim, snow, mud, etc. from causing problems with your rollers. What are you going to fill the gap in front of the tire with? This is going to be a big air scoop. However you don't turn the wheels that far at higher speeds so it might not mater.

I think it would be best to allow a little play such that there was no scoop effect unless it was a largish turn, at which point it can be assumed that the car is not going fast enough for the drag hit to matter. Two rods to the steering linkage would work best IMO. Note that these rods are pictured either side. They could be closer together and above the tire, in fact, that would probably work better. The magnets would still be desireable, IMO.

[The Toecutter]

That tandem Metro is pretty damn slick.

Ever consider electrifying it? With two seats removed, there is a LOT of battery room and freed up weight to keep you from going over GVWR.

A 1,500 pound pack of lead acid batteries might take that car 150-180 miles per charge at 65 mph. About 2/3 the range of most gas cars.

[95metro]

Okay guys, how about this for some serious aero-mods?



I've been drawing this up over the past while to see what the Metro would look like. I think it actually looks pretty cool like this.

The wing would be difficult and would take a lot of testing, but the idea comes from http://www.max-mpg.com/html/tech/main.htm

[GasSavers_katman]

I'd cruise Sonic in it!