wheel airdam - deflector - strake? design questions

[aerohead]

Ford did a lot of work on these with the Probe-IV concept car.They had them in front of the front wheels (but not behind!) and before and after the rears.The Probe also had active suspension so they could get away with stuff we can't.In addition to directing the air,the structures also improved the "sectional density" of the car,which softened pressure spikes in the areas where the wheels "erupt" from the body.The things we see on the Insight and Prius are probably a compromise for real world cars that must negotiate curbs,driveways,roadkill,tire "alligators",etc.,with a fixed suspension.The best example to feast your eyes on is the M.G. EX-181.Check it out at GOOGLE Images.

[lunarhighway]

that probe IV is one sweet car... looks like something from back to the future... or a family porche 944... a 0.15Cd and not much frontal area by the looks of it.
the EX-181 is realy nice, but i find it a little less interesting as it's, well little short of perfect...not much i could borrow for my car.

i've just cut up two 50CD-r spindle lids....I carefully cut off the top and unfolded them to form two 8.5x40 cm strips wich i plan to attach before the front wheels and suspention arm to the wheel well wall... it should project about 2.5 cm below the original bumper fairing. they'll curve in towards the inside so theyll direct some air to the center of the car... later i plan to install a partial bellypan there so i think that will be a good thing.

[bwilson4web]

Hi,

Originally Posted by lunarhighway

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this autospeed article has some info that might be usefull but it's not that complete that it can be used as an exact guide

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I did some work last summer to fabricate tow clamps for my NHW11 Prius, the version that followed the NHW10 model. This photo shows how Toyota replaced the two, short, flat, former wheel dams by a full length, ~2 inch, air dam:


As background, I needed to cut a gap in this short shield for prototype tow clamps. What is impressive is how small the air dam is in the production NHW11 Prius. The two small gaps in OEM air dam imposed no detectable loss of mileage.

What this suggests is an air dam only needs to keep the high speed air from impinging directly against the under body parts of the car. However, the next model NHW20 Prius put in more under body panels. The 2010 Prius has complete, under body panels.

Bob Wilson

[aerohead]

My thought is that the wheel pants on an aircraft with fixed landing gear would present ideal forms,with the cod-head leading edge and mackerel tail strake/fairing behind.---------------------------------- The trouble with automobiles is the clearance when we park,and go up and down ramped driveways.------------------------------------------------------------- I think the simple structures we see on late model cars are there to guide the air away from a head-on collision with the face of the tire traveling vertically down towards the road surface at road velocity.Kind of like running into a waterfall,with great turbulence.The simple panel steers the air around the face of the tire and is close enough to the tire face that it isn't torn off the car when it pulls up to a curb when parking.Ideally,the forward structure would be more like that on the airplane,it's just that airplanes don't have to park at a curb,so I think these simple panels are just a compromise to the practical necessities of driving.

[OfficeLinebacker]

Have any of you guys looked into airdams mounted to the control arms? The mounting would be a major PITA but if you can get it to move with the unsprung mass you can make it cover much more of the tire. You could really mold it well so on compression it would just move up into the wheel well.

I follow motor racing and I know in F1 where aero is King the single biggest contributor to drag is the open wheels. So I know there are gains to be had from protecting the things, especially with them turning as aerohead noted.

Cheers!