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Old 11-08-2008, 03:11 PM   #1 (permalink)
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various front skirt ideas

There seem to be a bunch of different ways possible to make front skirts. I'd like to divide them up between skirts with moving parts and those with no moving parts.

No moving parts: In this case you need to bulge the front fender out far enough to make room for the tire when you turn. You can limit the steering angle, narrow the tire, or narrow the track to make more room.

Moving parts: Guys on here have made one-piece top-hinged covers. Ford has tried inner fenders that push against a fabric cover. So far I haven't seen 2-piece or vertically hinged covers.

Ideas: Why not put the whole front fender on a hinge and/or space it outboard 2 inches? Front fenders usually only bolt on with a few M6 bolts. If you build a special hinged bracket (or spacer) where the fenders bolt up by the top of the strut towers and leave the rest of the bolts out, the whole fender should move. If you space it enough, you might not even need a hinge. Once the whole fender becomes the skirt, filling in the wheel well arch becomes simple.

Passive or active: The rollers that Basjoos used were great, but they take away clearance. They're a passive system, too. An active system would be to connect the hinged skirts to the knuckle or steering tie rod.

Other cars: As far as I know, they don't make a one-piece fiberglass drag racing front end for the Geo Metro. They do for some Honda Civics. Since the Metro is narrower...Why not put that w-i-d-e Civic front end on and fiberglass the wheel wells? The cowl and front edges of the doors might not match up perfectly...but who cares? Those are now vents!

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Old 11-08-2008, 03:54 PM   #2 (permalink)
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various

Quote:
Originally Posted by aspera View Post
There seem to be a bunch of different ways possible to make front skirts. I'd like to divide them up between skirts with moving parts and those with no moving parts.

No moving parts: In this case you need to bulge the front fender out far enough to make room for the tire when you turn. You can limit the steering angle, narrow the tire, or narrow the track to make more room.

Moving parts: Guys on here have made one-piece top-hinged covers. Ford has tried inner fenders that push against a fabric cover. So far I haven't seen 2-piece or vertically hinged covers.

Ideas: Why not put the whole front fender on a hinge and/or space it outboard 2 inches? Front fenders usually only bolt on with a few M6 bolts. If you build a special hinged bracket (or spacer) where the fenders bolt up by the top of the strut towers and leave the rest of the bolts out, the whole fender should move. If you space it enough, you might not even need a hinge. Once the whole fender becomes the skirt, filling in the wheel well arch becomes simple.

Passive or active: The rollers that Basjoos used were great, but they take away clearance. They're a passive system, too. An active system would be to connect the hinged skirts to the knuckle or steering tie rod.

Other cars: As far as I know, they don't make a one-piece fiberglass drag racing front end for the Geo Metro. They do for some Honda Civics. Since the Metro is narrower...Why not put that w-i-d-e Civic front end on and fiberglass the wheel wells? The cowl and front edges of the doors might not match up perfectly...but who cares? Those are now vents!
The movable skirts offer the potential for zero added frontal area,something experts laud the merits of.They also promise a "no-vent" architecture,which in the case of Trans-Am Firebirds and perhaps Corvettes tend to increase drag. --------- With respect to clearance,rollers need not encroach here,as they can be a single roller also,which contacts the wheel instead of tire,placed lower in the arch,"looking" into the void of the rim at each "end" of the wheel.-------------------- Also,by not "bulging" or "blistering" the skirt,the aft portion of the skirt can avoid the steep convergent angles which can trigger separated flow,the whole point of the skirt!---------------------- The only caveat I might concede to,is that a gentle bulging could create a "Whitcomb-wasting" or "Coke-bottling" or "high sectional-density" which could conceivably abbreviate pressure spikes along the path of the car between the nose and windshield area,something that would require thousands of pressure-tap readings to verify and practically outside the scope of ecomodding.--------------------------- Certainly,there are a multitude of solutions,however if you want a safe bet,follow Basjoos' and MetroMPG's lead,as I believe they have a water-tight design you'd be hard-pressed to improve upon at the gas pump.
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Old 11-08-2008, 04:31 PM   #3 (permalink)
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I do not think any of us have tuft tested this solution, but someone should know the answer.

While a full front skirt may be ideal, how much benefit would we get from a fender flare made out of rubber that would be a perfect contour to the curve of the tire which eliminates the gap of air between the tire and fender.

This allows for full suspension clearance and if made from rubber or other durable plastic any friction made by contacting the tire would just slowly wear the rubber or plastic away.

Would eliminating the turbulent air between the tire and fender be as beneficial as a full skirt if paired with moon disk caps?
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Old 11-09-2008, 11:18 PM   #4 (permalink)
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trik: I'd think it would have to be pretty close. You'd still have the tire sidewall dragging some air up and forward, messing things up, but not likely as much as the tread, which would be enclosed, no longer interacting with the air flowing down the side of the vehicle.
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Old 11-10-2008, 09:58 AM   #5 (permalink)
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I just remembered another one that I forgot about. You could go all "Thrust SSC" and steer with a (single in this case) rear wheel mounted far behind the car.

The Thrust SSC solution solves several problems. First, it allows the front wheel wells to be covered because the front wheels are no longer steered. Second, it allows the rear wheel wells to be covered because they no longer house wheels. Third, it turns the car into a reverse trike (2F,1R) by mounting a wheel several feet behind the car. This very long wheelbase FWD rear steer car would be very unusual...but based on a proven design used on the fastest car on Earth.

http://www.thrustssc.com/thrustssc/D..._the_Mini.html

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