Do wheel skirts really work?

[trebuchet03]

Originally Posted by MetroMPG

So your front wheels will be exposed & disc covered? GoOne style?

Yep. Minus the suspension :P


mind you, this is not the most up to date version - but the overall shape has stayed the same.


I really wish I had the money -- I'd buy a model of my car, build a water tunnel (which can be done cheaply with decent flow visualization results) and test :P You can even tackle the cross wind scenarios I didn't even think of those situations until now :P

[rh77]

I'm constantly complaining, with the crosswinds, that I need a rudder.

I've got it -- 4-wheel steering, and you aim the front of the car into the wind, and drive "straight". Gusts, however, would be a problem

RH77

[rh77]

Originally Posted by theclencher

Just have castering rear wheels and toe brakes for each front wheel... and be an alert driver!

I think you just found the next competitive motorsport! It's got to be harder than drifting

[trebuchet03]

Originally Posted by rh77

I'm constantly complaining, with the crosswinds, that I need a rudder.

I've got it -- 4-wheel steering, and you aim the front of the car into the wind, and drive "straight". Gusts, however, would be a problem

RH77

I think this fiat can do that :P

[rh77]

Originally Posted by trebuchet03

I think this fiat can do that :P

Perfect! Where can I get one?

[trebuchet03]

Originally Posted by rh77

Perfect! Where can I get one?

Poland I'm told :P Only a limited number manufactured.... 1

[BeeUU]

Originally Posted by theclencher

I'll take a stab at it although I won't claim to know for sure what the heck is going on there!

It's an exhaust duct and for whatever reason, instead of exhausting air at the rear or top of the bodywork (don't the rest of the cars do that?), the spot in front of the rear tire was chosen, so to promote flow through their "closed" ducting system and also reduce drag from the outlet on back they had to add the skirts. (?)

Generally, during a race the tires are changed often, the skirt would increase the time to change the tire significantly. The gain in speed/mileage with a skirt is less than the loss of time during tire change.

[red91sit]

Originally Posted by MetroMPG

This one throws an interesting twist in the aesthetics vs. style debate:



Nissan R89C with rear wheel skirts

I doubt these are on for styling reasons. That said, if they were useful, why weren't they adopted by every race team? Was the theoretical speed gain offset by the extra time the pit crew needed to remove/reinstall the panel for a wheel change? Brake cooling issues?

Inquiring minds want to know...

I've always had a thing for these vehicles, and therefor have done a little bit of research into them. The rear wheel skirts did increase top speed, but there was not only the problem of having to remove them in the pits, but also the fact the tires would run hotter than if they were exposed, and of course the hot brakes, but I'm sure these had their own cooling ducts. I think one of these cars would make a GREAT FE car if you just remove the massive engine, and the massive cooling ducts. The rear spoiler could go as well, and you'd have a VERY clean car. They share a lot of aerodynamic principles with the insight, radiused front wheel wells, covered rear wheel wells, very little detached flow, No A pillar turbulance. The use of Naca ducts is great too! Super light, carbon fiber bodies, and spaceframe chassis. MMM i bet you could get well over 100 mpg with that setup.

Another strange thing is these cars were basically Unlimited as far as modifications, they were on a fuel ration system. They would generate ridiculous power and top speeds in practice session and qualifying, 1000 hp, +200 mph! So fuel economy was actually important to these racers!

I find that exhaust placement very strange on these cars, I see no benefits to routing it to the side of the cars. My perhaps it's to push the laminar flow away from the turbulant wheels? as it is a feature shared on several other group c cars, skirted, and non.

Wheel skirts are definetly different for every car. Mine are HORRIBLE to begin with. Therefor adding just half wheel skirts in the rear netted me a an avg. of 1-2 mpg better at 60 mph. A whole 10% gain! I think test after test has proven them to be good. I"m a little confused as to this topic?

[MetroMPG]

Cool, info red91. Thanks.

Originally Posted by red91sit

I find that exhaust placement very strange on these cars, I see no benefits to routing it to the side of the cars.

Are you sure those are exhaust and not cooling outlets? I've seen a few photos of these cars racing, and if they were exhaust outlets, I would have expected to see some soot/crud on the bodywork aft of them. But they're clean in the pics I've seen.

[zpiloto]

It's been a cold rain all day today. I noticed looking at the cars as I was driving around that there is significantly more spray from the front then the rear wheels. Which would make me think that some kinda of coverage on the front would decrease drag more than on the aft wheels. Has anyone run across any data that reflects that?