Designing/building front wheel skirts v.1.0 (Geo Metro)

[aerohead]

Please,don't anyone attempt to do the skirt w/o hinges.The one I did for the T-100,even though blistered out to allow reduced turning radius,rubs at the slightest provocation and is a constant source of stress and displeasure! ------------------------- I'm going to do a double-articulated linkage for mounting the skirt,as it will move like a parallelogram,away and up simultaneously,the skirt always parallel to the side of the car.------------------------------ No benefit aerodynamically,but it will let me play with this mechanism,which I intend to also use for the canopy on the hyper-mini.

[Cd]

Bassjoos : Just curious : what does it sound like when they make contact ?

Metro : Dont't mean to hijack. Care to comment on the rubbing issue and how you will handle it ?

[basjoos]

They sound very similar to the noise produced by a TIE fighter in Star Wars. The aluminum sheet covering picks up and transmits the noise produced by the rollers. The earlier coroplast covered version was a bit quieter.

[MetroMPG]

Metro : Dont't mean to hijack. Care to comment on the rubbing issue and how you will handle it ?

I'm thinking of attaching some teflon sheet or other slippery plastic where the tire will contact things. It'll be mounted to the metal frame behind the skirt.

Originally Posted by basjoos

They only make contact during a sharp turn, like turning into a driveway.

I think mine will be more sensitive than that. Not enough to contact in a lane change or gentle bend in the road (less than 1/4 turn of the wheel), but I'm going to try to get them fairly close to the tire to minimize frontal area and try to keep attached flow on the aft side of the skirt.

---

I worked on things a bit today - flattened a length of copper pipe to form the bracket that I'll mount the hinges on. I jacked up the a rear corner of the car to compress the front suspension on the opposite corner to double-check clearance to where I was going to run the bracket. Decided to position it up higher than I showed here:



I've got it positioned at the halfway point between the bracket drawn above and the top of the wheel arch.

I also picked up some steel bar stock (fairly light) to make the frame. I'll work on that tomorrow and take some pics.

[Blue Bomber Man]

What about just filling in the gap between the wheel and the wheel well, make it solid, and leave the minimum clearance for turning. Then put some sort of rubber stripping around the rest that can basically seal it when the wheel is straight but will flex enough for the wheel to pass through it.

At first you might think it wont be nearly as effective because it doesnt cover the spinning side walls of the tire, but I bet most of the turbulence created from the spinning tire is actually from the tread part of the tire that is perpendicular to air flow.

This coupled with some hub covers should be very effective, and possibly even more then a full cover because it wont increase frontal area and might have better laminar air flow.

Could do another tuft test with a cardboard cutout to see

[MetroMPG]

It's not a bad idea.

Couple of issues: Don't forget the cutout has to accomodate the movement of the wheel with suspension travel too. So it can't just be a simple circle.

Also, the wheel cover/tire on my car isn't flush with the surrounding bodywork. It's recessed at the top & sticks out relative to the bodywork below the center of the wheel. Makes it more complicated to design a gap filler with smooth lines.

Ever see the "bristles" on transport trucks above the trailer wheels to keep spray down? Maybe that could work as the "gasket" bit that has to permit the tire to pass through when turning.

[BrianAbington]

very interesting. I like the hinge bracket.

[MetroMPG]

Much more refining yet to do, but I got the hinges mounted on the flat copper pipe that uses existing screws in the wheel well lip. Need to drill one more screw hole in the forward part, but I can do that in the plastic bumper, so no rust issues there.

Need to trim the copper, and I may replace it with stainless if I don't think it's sturdy enough with the full weight of the completed frame & skirt:



Below: side view. The frame is just tacked together at this point. Going to add some triangulation for strength.



Below: view from above... There's about a 1 inch gap between the tire/hub cap and the frame. Accomodates 1/4 turn of the steering wheel before contact.



Front view:

[gascort]

Aside from the hinge being slightly front-mounted (you are still doing that, right?), you could add something on the front bumper right in front of the skirt to divert air around it to make sure air doesn't get under there and lift the skirt away from the car.
As for the slippery material backing or conveyor roller, what about using a layer of coroplast? I'm assuming you have lots of extra laying around like some of us do..

[Tango Charlie]

Very nice, MetroMPG. You mentioned using teflon instead of rollers. I've heard of the rock crawler guys making skid plates with the slick plastic stuff they make cutting boards out of. Maybe that'd work for ya. It'd be cheap and easy to cut/drill.