Front skirts in production
 

Found out there are some beautiful aerodynamic buses in production with front wheel skirts. Turning photos reveal a lot.


http://i148.photobucket.com/albums/s...b/IMG_2613.jpg

http://www.ssfoto.net/images/lvb44.jpg

http://www.ssfoto.net/images/lvb64.jpg

http://www.ssfoto.net/images/lvb55.jpg

http://www.rapidtransit-press.com/apta-nabi01.jpg

http://i54.photobucket.com/albums/g1...s/IMG_7675.jpg

http://i54.photobucket.com/albums/g1...s/IMG_8431.jpg

Great find! Last picture seems to indicate that the front wheel skirts are mounted to the non-rotating portion of the wheel hub... would be interesting to get some detailed information about the mounting mechanism.

Seems like that could be mimicked on a car using a mounting system similar to the Lotus / Locost 7 front fenders, like so:

http://ecomodder.com/forum/attachmen...1&d=1278997732

Unlike the Lotus 7 fender, it wouldnt be necessary to provide coverage over the top of the tire, only along the face of the wheel... so it could be made for "relatively" easy removal for access to the wheel & tire itself.

:thumbup:

XJguy -

Pretty cool. In the LA Metro case, I have read that the secondary (or first-ee-air-ee?!?!) purpose is to protect people from getting caught in the wheels.

CarloSW2

NachtRitter -

Yeah, but that cover could reused as part of the mounting structure. I think you could lower it down to the diameter of the wheel (but not the tire).

CarloSW2

When I saw that, my first thought was "WOW, I've got to try that!" But my second thought was "And how am I going to get snow chains on that?"

Those buses look simply awesome, not just the wheel cover part..The second picture especially reminds me a lot of trams (streetcars) I guess they figured out aerodynamics does make a difference, even in slower moving buses

http://jfi.uchicago.edu/~rschroll/france/00126.jpg

uhh....there's a word for that. It's called "Primary." :thumbup::turtle:

:D Funny how words escape the mind sometimes!

I realize one issue with my suggestion is that you'd have to account for suspension travel within the wheel well... Might be able to mitigate that by limiting the "height" of the cover (so it doesn't extend much beyond the top of the wheel) and maximizing the "width" (front to back of wheel well). I would draw it, but my drawing skills are worse than a 2 year old's :p . Anyway, then the gap from top of wheel well to wheel cover could be closed using a short flexible skirt ("mini-skirt").

This is just arm-chair designing, of course... no idea if it would actually work in real life. Maybe a basjoos style front wheel skirt would be significantly easier to implement...

Thanks that is a solution for the front wheel that i had not thought about and the Lotus 7 pic helps for another way to mount it. I really need to make some wheel skirts.

1984 probe iv
 

I'm not sure if GOOGLE IMAGES has any photos,but the Ford concept had the complete inner wheelcover.
4-season performance might limit these to areas outside the snow-belt.Don't know.
P.S. The French 'Dauphin',circa 1934 had virtually an identical setup.Back to the future!

The issue with having the skirt attached to the kingpin is that it adds to the sprung weight. (This probably doesn't matter much on a bus!) I'm hoping to attach it to the inner fender and only connect the steering tie rod move the skirt.

It is interesting that it would seem to worth doing this on a local metro bus.

Neil -

Seems like it does make more sense to mount the skirt "support structure" to the body of the car rather than to the wheel itself. Might be able to use the top of the shock tower and the control arm mounts as the three attachment points for the swivel at the top? I think the issue there is that swivel piece would need to be relatively beefy to hold up over time.

On the other hand, the heaviest part of the support structure would be the frame... that wouldn't be more than a pound or two, would it? The skirt material itself can be relatively light. So even if it were mounted on the wheel, it isn't much unsprung weight.

It probably comes down to the ease of construction and maintenance vs the ideal.

I would love to do something like this but how would you change a flat tire?

You would have to undo the fasteners on the skirt, to get access to the wheel and lug nuts?

what happens if that bus hits a bump while turning i dont see much of a gap between the skirt and the top of the fender.

Many of the Delahayes have front wheel skirts, but I have not been able to find anything showing how they function.

http://www.webkits.com.br/news/artic...3-Delahaye.jpg

Or hits a bump at any time! Ya, I was wondering that too... I'd be very interested in seeing the mount mechanism.

From the pic, it seems like the front fenders are wide enough to allow the front wheels to space to turn... so they sacrificed frontal area for the ability to completely cover the wheels.

A reference from a reproduction house indicates that (see Delahaye USA - Bugnotti).

Neil -

Thought about your idea (of a front wheel skirt with a vertical hinge so that only the half that needs to get out of the way moves during a turn) some more and I would agree that is an excellent approach... not that you need my approval or anything ;) It could be done really simply (I think) using a basjoos-style interference approach (no need to tie into the steering rod necessarily). Getting the proper support framework in place would be the trick.

OK, found a few better pix...

First, I realized that the picture of the white NABI BRT bus shows it after it has settled down on it's air suspension, so the gap on the front wheel skirt is less than it would be while driving... a bit deceptive:
http://www.rapidtransit-press.com/apta-nabi01.jpg

The actual gap when the suspension is at driving height is a bit more noticeable:
http://ecomodder.com/forum/attachmen...1&d=1279177327

Second, a good side shot of the Las Vegas bus (the StreetCar RTV by the Wright Group) shows very well what I meant when I said: http://ecomodder.com/forum/attachmen...1&d=1279177329

Now that I look at the original pics of the StreetCar posted by XJGuy, I notice the gap on the top of the front skirts a lot more.

NachtRitter -

This reminds me of the capads, aka a weighted floating cover, except they are extending the "cap" outside the diameter of the wheel :

CarloSW2

I think those are mostly for looks. I read somewhere that adding a 'bulge' just to get a better shape is not worth while. The increase in FA outweighs the reduction of Cd. Maybe adding a bulge and covering the front wheels breaks even?

Re verticle hinge: if the wheels turn left then the rear opens on the right side and the front on the left, am I correct? Something like the suicide doors in the Panhard Dyna Z?

http://ecomodder.com/forum/attachmen...1&d=1279178642

Could this cause a parachute effect on one side when turning above a certain speed?

Nevyn -

Ha ha, I know egg-zactly what happened. I was thinking "first, second(ary), third", so my stoopeed brain evicted primary as an option.

CarloSW2

Westfield's iRACER car does exactly this. I saw it at Goodwood last week and the wheel covers are unsprung weight but made of very lightweight plastic. It also has flexible bodywork!

Do these around-the-tire skirts reduce drag by A: partly blocking the wheel-well opening or B: reducing the drag of the wheel/tire or C: both?

Piwoslaw...

Ya, kinda like that... The idea is that at high speeds you're not going to be turning all that much anyway... and the cover should have a little bit of a lip to avoid "catching the wind" at speed.

Carlos...

Pretty cool... somewhat ironic that the wheel bearings allow the wheel to turn, and then another set of bearings are needed to keep the cover from turning... :rolleyes: Too bad it isn't easier to mount something like that on the spindle from the outside of the wheel.

David...

The goal is to allow air to flow past the entire body of the car with minimal disturbance. The covers essentially allow smooth air flow across an area that is typically very turbulent. Sooo... I guess that would be option "C"? :)

Looks like the front skirts may be mounted directly to an axle sleeve that extends through the center of the wheel. The skirts look too large and heavy to be attached from the inside only to me.

@ bike4miles - perhaps you are right, but it could just be that they're fibreglass and they're professionally made, thus I assume actually quite light. If you just attach that skirt at the front, back and top, it should be quite sturdy, especially if in plan your front, back and top mounts form a triangle shape too where connected on the suspension.

This should be more than sturdy enough for a lightweight fibreglass / plastic part.

function
 

I think that the wheels are inset far enough that at full lock,the tire runs just short of bumping into the skirt.
Porsche's 60K10 was like this,and the 356 Panamerican racer.Nash Aeroflyte also I think.Metropolitan?
Sounds like we need to dedicate a thread to skirts,past and present.

This got me wondering why a fully-enclosed front fender like the Delahaye wouldn't be a a reasonable proposition for an ecomod. Properly shaped, the small increase in frontal area would (should?) be more than offset by the large reduction in drag. Overall vehicle width shouldn't be an issue - if the full-size dually pickups fit in a lane, so should bulbous front fenders. It would also eliminate all those complex mounting and articulation problems.

Negative-offset front wheels would help, as long as one doesn't try to emulate Messrs. Vettel and Button.

curb-finders
 

I like the simplicity of the bulbous fender/skirt.The added frontal area would eat into the gains and parking alongside a curb could spell destruction if you forgot they were down there.
Simple curb-finders might help as a 'reminder.'

1934 Dubonnet Dolphin
 

Let's try this:
http://m.blog.hu/au/autohistory/image/Dubonnet Dolphin_01.jpg
This computer wouldn't allow the link.
If you want to see it,just GOOGLE IMAGES 1934 Dubonnet Dolphin
Sorry!

Here you go:

http://m.blog.hu/au/autohistory/imag...Dolphin_01.jpg

Very interesting approach... Those front skirts also look like they are attached to the hub (or some part of the spindle assembly) so that they can turne as the wheels are steered... I'd also guess there is little or no suspension to worry about.

Another view of the Dubonnet Dolphin

http://i13.servimg.com/u/f13/10/09/09/35/dubonn10.jpg


Ironically, Ecomodder is the first hit I get when I search for "Dubonnet Dolphin" ... :cool:

hub
 

If I had to guess,I would think that the spindle is stepped and that after the section for the castelated pre-load nut and cotter-pin,there is a second section,perhaps with a square section to which the outer fender support is attached and locked in where it cannot dance around.
Thanks again for photos!

Cool! OK, anyone plan to build one of these? I think it's important to clean up the front aero flow to maximize the impact of boat tails, side skirts, and rear wheel skirts.