Areo

[VPT]

http://img138.imageshack.us/img138/8297/areoplate020.jpg

http://img413.imageshack.us/img413/3778/areoplate027.jpg

http://img534.imageshack.us/img534/1719/areoplate028.jpg

http://img12.imageshack.us/img12/7344/areoplate032.jpg

http://img294.imageshack.us/img294/9680/areoplate033.jpg



You have to bring the car back sometime So I can tack on the VPT tag.

[Getsideways]

will do thanks for doing the work didnt make any noise at low speed in town so we should be good there ,,.
I'll try to make it blow off at the track this weekend

[VPT]

Sounds good! I want to hear that you made a valiant effort to make it blow off too!

[thatguy]

very nice... and why havnt i gotten a vpt tag

[VPT]

very nice... and why havnt i gotten a vpt tag

I haven't had the steel/stainless ones made yet.

[mrslysly]

Looks good. Isn't it aero? Areo sounds like the chevy aveo. One question about this, why the fins? You created the flat plate to reduce the air drag/turbulence from the lower valance but you didn't create a zone to create a vacuum. Which is usually the reason that the fins are required, to smooth out the turbulence generated by vacuum.

This is my thinking on everything that I've seen and read about the aerodynamics of go-fast cars. You remove as much air from going underneath the front of the car. You then create air channel(s) underneath the car to direct the air that is underneath the car thru said channels, which are designed to reduce turblence/drag and speed up the air's velocity. This air then exits behind the car. The exit area is design to expand that airflow creating a vacuum which pulls more air thru the channels underneath the car, creating a vacuum underneath the car, thereby helping it generate downforce. Which in the end generates more pressure on the tires and better grip all without having to increase wing angles which increases drag.

[ragdoll]

What material was used?

Reusing my photo from the picture thread...

http://www.pbase.com/cdandar/image/102523631/original.jpg

Seems to be the same idea as this here? Although this is carbon fiber. This is under my RS4 as well but is plastic. My S4 has just a sheet of plastic to the bumpers to keep out any drag, no fins in rear on that car though.

[Dizmm]

the overall goal it to block off the front and sides of the car from air getting underneath it, and open then up the back end of the car.

[mrslysly]

Notice how its not the entire rear area open on the RS4. The sides still go all the way down. This is to help create that tunnel effect with a larger opening at the end.

Not like it has a drastic effect on our cars as they still suck enough air under the front and sides. Most of the ones on the cars that I have seen are more for looks than anything else. Even the Mazdaspeed rear skirt for the Rx8 was mostly looks. A quick glance at it and you could tell it really wasn't for aero effect.

[VPT]

Looks good. Isn't it aero?




Yes Aero, I was in a hurry.

[VPT]

What material was used?




6061 aircraft aluminum and as you can see in one picture it is .063".

[Getsideways]

Looks good. Isn't it aero? Areo sounds like the chevy aveo. One question about this, why the fins? You created the flat plate to reduce the air drag/turbulence from the lower valance but you didn't create a zone to create a vacuum. Which is usually the reason that the fins are required, to smooth out the turbulence generated by vacuum.

This is my thinking on everything that I've seen and read about the aerodynamics of go-fast cars. You remove as much air from going underneath the front of the car. You then create air channel(s) underneath the car to direct the air that is underneath the car thru said channels, which are designed to reduce turblence/drag and speed up the air's velocity. This air then exits behind the car. The exit area is design to expand that airflow creating a vacuum which pulls more air thru the channels underneath the car, creating a vacuum underneath the car, thereby helping it generate downforce. Which in the end generates more pressure on the tires and better grip all without having to increase wing angles which increases drag.

you answered your own question the fins speed up the air negating as much lift as possible. so why wouldnt they be used?
the goal is next year or late this year to finish the rest of the underbody anyways , but i want more research behind that first

[TomKat]

I think you should have gone with the JDM EVO rear bumper for maximum effect.

[ragdoll]

I think you should have gone with the JDM EVO rear bumper for maximum effect.

What's better on that design?

[ragdoll]

Notice how its not the entire rear area open on the RS4. The sides still go all the way down. This is to help create that tunnel effect with a larger opening at the end.

Not like it has a drastic effect on our cars as they still suck enough air under the front and sides. Most of the ones on the cars that I have seen are more for looks than anything else. Even the Mazdaspeed rear skirt for the Rx8 was mostly looks. A quick glance at it and you could tell it really wasn't for aero effect.

Although its more comprehesive on the RS4, my RS4/S4 both come stock with a "skid plate" under the entire engine bay area and wrap around the sideskirt/rockerpanel areas of the car as well(along with in the rear as stated above. Although VPT's setup is more comprehensive than either of my cars). Am I off my rocker? I could have sworn the Evo comes with a similar setup stock? At least under the engine bay and sideskirts?

[Pointdsm]

My 1982 Mazda Rx7 also has this under the front of the vehicle, going from axle to axle and rear to the firewall. Very well designed.

[JamesHell]

That is actually preventing the air from "catching" the bumper cover on the way out more than creating a vacuum. The fins are almost always relevent. Anytime you have a large flat surface the air has a tendency to eddy off of the edge. The theory is that by reducing the size of the eddies by slicing them it reduces the drag force created by the eddy.
BTW this is all only going to make a difference at high speeds. Just guessing since all situations are different but I would say around 120 mph or more.

Nice work either way.

[Dizmm]

i have a great aero book i can barrow you. it goes in very good detail on undertray design.

The JDM rear would maybe leave a bit larger opening in the rear creating more vacuum. Also cutting the stock rear bumper is something lots of the standing mile guys will do. it adds downforce without adding more drag.

The 06 STi’s have near a complete undertray throughout.

[Pointdsm]

The only reason for the fins are to tiddy up the air exiting the car. The fins can be parallel or slightly divergent. The purpose of this diffuser is to continue the low-pressure made by air being compressed under the car (Bernoulli's rule). Ride height plays a huge roll in this setup, as the lower the car, the better it will work. It would be better to have this undertray connected to the floor of the car, and slowly divert the air exiting the car at a slight angle, eliminating turbulence and allowing the pressure change to be slower. Without fins on the outside of the undertray, the effect will not be near as great as I could be. You are simply not letting the air be caught by the bumper, instead of directing the pressure out of the car, maintaining low pressure under the car further and creating downforce.

[Dizmm]

a real undertray:

http://www.lambopower.com/forum/uploads/monthly_11_2008/post-14091-1227424928.jpg


VPT, i want one like this: how much?
http://www.lotustalk.com/forums/attachments/f92/135358d1254619988-new-side-sills-flat-undertray-gigantor-diffuser-large-pics-dsc01264.jpg

[VPT]

Thats a photoshopped skate ramp.

[Pointdsm]

The Ferrari pictured, very correct dizmm.

[SgtRauksauff]

Porsches have a very nice undertray also. even has little NACA ducts where the fuel lines do 90° turns, to help cool the fuel down.

What effect, though, does putting the tray up inside the bumper cover like that? Doesn't that kinda defeat some of the gains to be had, putting an interruption into the laminar flow like that?

--sarge

[VPT]

What effect, though, does putting the tray up inside the bumper cover like that? Doesn't that kinda defeat some of the gains to be had, putting an interruption into the laminar flow like that?

--sarge


Because it looks gay on the outside of the bumper and it already will do minuscule amounts of improvement so that little tiny bit of bumper overhang will mean less than almost nothing at all.

[ragdoll]

Riduculously limited production Lotus Exige S 240 at the local Lotus dealer

http://www.pbase.com/cdandar/image/116251083/original.jpg

[mrslysly]

you answered your own question the fins speed up the air negating as much lift as possible. so why wouldnt they be used?
the goal is next year or late this year to finish the rest of the underbody anyways , but i want more research behind that first

The way you have the fins setup on your car there is no tunnel or any real channel so those fins do not help speed up the air stream, just simple smooth out a little of the turbulence. Honestly, the fins seem moot as there isn't any other aero piece in place to utilize them.

[mrslysly]

My 1982 Mazda Rx7 also has this under the front of the vehicle, going from axle to axle and rear to the firewall. Very well designed.

The Rx cars had this panel under the engine bay for splash reduction as the rotaries didn't respond well to direct large amounts of water on hot rotor housings and also to help force air down the exhaust tunnel.

[ragdoll]

http://www.youtube.com/watch?v=CMNry4PE93Y

[mrslysly]

http://www.youtube.com/watch?v=CMNry4PE93Y


Well said.

Miackhahaahkakff, you should have VPT fab up a quick release dragger front air dam and side skirts. Get ultimate vacuum generation under the car.

Is there a windtunnel nearby we could rent??

[ragdoll]

Well said.

Miackhahaahkakff, you should have VPT fab up a quick release dragger front air dam and side skirts. Get ultimate vacuum generation under the car.

Is there a windtunnel nearby we could rent??

I think Tom has a box fan. Frank can blow a cigarette into the fan to monitor aerodynamics over the car.

[05Saab]

I think Tom has a box fan. Frank can blow a cigarette into the fan to monitor aerodynamics over the car.

Perfect R&D! :cool:

[VPT]

The way you have the fins setup on your car there is no tunnel or any real channel so those fins do not help speed up the air stream, just simple smooth out a little of the turbulence. Honestly, the fins seem moot as there isn't any other aero piece in place to utilize them.




It is moot like you said because the rest of the car doesn't have panels. The air is already broken up and turbulent before it gets to the rear undertray. So this things basic job it to keep air from getting caught in the massive cavity in front of the rear bumper and straiten in out just a tad before it exits to the rear low pressure zone behind the vehicle.

A whole car undertray would be needed to utilize any kind of actual air control.

[Getsideways]

The way you have the fins setup on your car there is no tunnel or any real channel so those fins do not help speed up the air stream, just simple smooth out a little of the turbulence. Honestly, the fins seem moot as there isn't any other aero piece in place to utilize them.

There is still turbulent air exiting the back of the car It DOES smooth it no matter how little the effect and like i said in my previous post this piece is just the first there will be more added eventually but not right now i have other things to focus on first ,,

[VPT]

^ HA, same time.

[mrslysly]

Looks like its a good start then. Sparky time come speed bumps and steep slopes.

[DirtyBird]

Steep Slopes?

























http://www.cameronmcneish.co.uk/wp-content/gallery/moroccos-mt-toubkal-in-winter/on-steep-slopes.jpg

[devlish]

Steep Slopes?

http://www.cameronmcneish.co.uk/wp-content/gallery/moroccos-mt-toubkal-in-winter/on-steep-slopes.jpg

I've skiied steeper