Aero Devices diffusers, wings, spoilers, etc

[MichaelD]

Has anyone added an aero device or devices to their car? If so what were the positive and negative effects? What prands or homemade specs?

 

Thanks for sharing.

[MNlotus]

i havent but i have been looking at a diffuser to add to my car. i found this one on reveries sight..... i would have to move my backup lights though if i got this so it would get clean airflow.

[Ian7]

Interesting idea in that photo, but given the 7's high (relative to a race car) ground clearance, and the short axial length and steep angle of the "diffuser", I'd be astounded if this made a measurable difference.

[Kitcat]

Michael:

 

THe se7en in your photo shows you running a full standard windshield.

 

Have you tried substituting a driver's side Brooklands screen or simple wind deflector? My experience w/Brooklands is that it added a bit of top speed as well as improved acceleration. (I left it home for the trip to LOG30/Summit Point as I drove my car there and wanted the added protection on the highway and against the possibility of rain).

 

Mike M.

[Croc]

Diffusers seem to be readily available for Sevens in the UK. Here is Fluke motorsports offerring:

 

http://www.fluke-motorsport.co.uk/newImages/182_2.jpg

 

http://www.fluke-motorsport.co.uk/carbon-fibre-multiplane-contoured-diffuser-p-182.html

 

Fluke claims the following:

 

This has a three-fold effect

• reduced drag from the rear fuel tank area which typically acts as a parachute without underfloor covering
• downforce creation from low pressure area created by aerodynamic profile of the diffuser - increased further as the channels aid the airflow keeping it attached to the contour of the diffuser
  
• cleanliness! - covering the underside rear quarter of the car as such helps to keep the dust, mud and much from coating your suspension, diff and fuel tank!
  

I thought it was interesting that the diffuser has been mounted rearward to effectively lengthen the car for aerodynamic purposes.

 

They also offer undertrays to fill in the open space:

http://www.fluke-motorsport.co.uk/carbon-fibre-undertray-suitable-for-caterhams-p-179.html

 

 

This is the claim, however I am not aware of any technical study that backs this up. Fluke does actively race so there may be some experience they have that justifies their product offerring.

 

The only publicly available study about the aerodynamics of Sevens was the Caterham study when they were developing the CSR. There were 3 key modifications made to reduce lift:

- winglets on the side of the nose

- venting the airflow from the radiator up through the nose

- moving the suspension inboard.

This was posted somewhere on USA7s in the past and probably could be found by search.

[MNlotus]

do they only offer that undertray for the vauxhall motor cars? i didnt see the option for a zetec. also will that diffuser fit pretty much any caterham?

[scannon]

I have the whiskers (winglets) and the CSR chin spoiler on my SV. Scary light front end moved from 110 mph to 135 mph. Well worth it to me.

 

The chin spoiler is hard to see in the photo below but it made a nice place to mount my front license plate.

[MightyMike]

The front end of my birkin is well planted at higher speeds. Not sure if this was the result of the canards (whiskers). I purchased the rear diffuser from Dick at Texas Motor Works. It should fit on most S3 sevens.

 

http://i52.tinypic.com/eqt9ar.jpg

http://i56.tinypic.com/vhdi09.jpg

 

http://www.carbonmods.co.uk/Products/Carbon-Fibre-Kit-Car-Nosecone-Canards__CMNCCSM01.aspx

[Mondo]

Hard to believe those little winglets would make a difference you could feel.

[MNlotus]

mightmike, how do i get a hold of one of those diffusers?

[MightyMike]

Contact Dick Brink at Texas Motor Works. I paid $200 for the piece.

 

http://www.texasmotorworks7.com/

 

Mike

[MichaelD]

Michael M.

 

For the last year I have run with a 5.5" windscreen that is interchangable with a stock windsceen. Since my car has clamshells I added a front splitter attached to 5" wide cannards. This resulted in a new top end od 145-150 mph.

 

I am considering the addition of a full closed engine bay and a diffuser. The one from Fluke seems to look like it will work with a wing.

 

However, it is expensive and I do not know of anyone that hase possibly nd . However

[slomove]

Hard to believe those little winglets would make a difference you could feel.

 

That was my first thought when I saw them on a CSR (compared to all the other bulky suspension hardware protruding from the chassis). Without detail analysis of the aerodynamic efficiency, the dynamic pressure of air at 150 mph is (if I am not mistaken) about 0.4 psi. Given the small horizontally projected area of maybe 2-3 square inches, I suppose the best lift you can get of such a whisker is maybe 1 or 2 pounds which does not strike me as significant. Typical aerodynamic helpers tend to be rather snow-shovel size or bigger.

 

But maybe there is some other aero magic going on and I do not have measurement data to prove otherwise. So who am I to question the believers?

[escondidoron]

the dynamic pressure of air at 150 mph is (if I am not mistaken) about 0.4 psi.

 

Agreed.

[Croc]

The following gives another idea for aerodynamic tinkering - the front wings.

 

Extracted from this article:

http://www.insideline.com/caterham/csr/2005/european-first-drive-2005-caterham-csr.html

 

Caterham chucked the regular Seven's De Dion rear suspension into the garbage to give the CSR fully independent double wishbones. New F1-style inboard dampers live up front, where suspension refinements sharpen the steering and reduce aerodynamic drag. Believe it or not, the CSR was tested in a wind tunnel, a place which Caterham's technical director, Jez Coates, admits no one would expect to find the coffinlike profile of the Seven.

 

During testing, it was discovered that the car had 100 pounds of front-end lift at 100 mph. The dilemma was eliminating the lift, without messing up the traditional look of the car — Porsche 911 stylists can relate to this quandary. Reprofiled front wings that sit closer to the tires reduced 35 pounds of lift. A chin spoiler, air ducting for the front radiator exiting out the top of the nose cone, and tiny, nearly invisible winglets clawed back about 7-10 pounds each. The net result: lift of 38 pounds at 100 mph.

 

Then again you may not want to go away from the clams - I do like that look and can understand some people preferring them.

[Kitcat]

Hijack:

 

Mighty Mike, everytime I see a photo of your car I am blown away by how perfect it is.

 

Mike M

[escondidoron]

nearly invisible winglets clawed back about 7-10 pounds each

 

Its pretty hard to believe that the winglets produce 7# negative lift each just looking at pictures of them. They are so tiny! It sure seems like the much larger chin spoiler and internal radiator ducting would have a much larger contribution to overall lift reduction than the winglets. Even taking into account the airspeed reduction due to the drag of the radiator.

 

The dynamic pressure at 100 mph is only about 0.12psi. However, if the little winglets are 5" by 12" each (60 sq.in) with 100% effectiveness (coefficient of lift equal to 1) they could produce the stated ~7# negative lift. Their overall contribution to lift reduction could be accentuated by cleaning up the airflow around the sides of the nose a bit by reducing drag where the front suspension enters the body work. Another consideration is the blunt nose shape. It likely makes quite a large boundary layer disturbance that continues well back along the sides of the nose before the airflow is reattached to the body work. This would decrease their potential effectiveness by not being fully exposed to clean airflow. But if they stick out far enough to catch the undisturbed airflow they could help to reattach the boundary layer sooner which could also increase effectiveness.

 

Anyhow, its a pretty good job by the aerodynamicist to reduce the lift by 2/3 especially if the winglets really do provide 7# lift reduction per side!

[Sean]

Its pretty hard to believe that the winglets produce 7# negative lift each...

 

I read it as 7-10 lbs. for the two winglets combined, so: chin 7-10; ducting 7-10; winglets 7-10. Seems about right to me, and it adds up.

35 for front wings

+9 for chin

+9 for duct

+9 for whiskers

62 total, leaving 38 remaining from the original 100 lbs.

 

Here is a photo of the Freestyle diffuser-type thing, with go-fast coating (dust):

 

http://i321.photobucket.com/albums/nn384/BBL-Sean/2009-01-01_4.jpg

Edited December 1, 2010 by Sean

[Alaskossie]

I wish Caterham would offer the ducted nose and the chin spoiler for the Series 3 -- there is no reason why the earlier, narrower Caterham should not also be able to take advantage of these anti-lift improvements.

 

Now that I think of it, I believe the S3 R500 Superlight does have the ducted nose.....now if someone could just solve the problem of excessive heat buildup in the engine bay caused by the redirected airflow through the nose and not through the bay, a ducted nose would be all gain and no pain.

 

As far as rear diffusers go, this looks like an area where a beginner in the art of carbon fiber fabrication could hone his skills, without any mistakes being too visible to the hoi polloi.

 

I'd like to try my hand at it, after I re-profile a new custom gas tank for more capacity....

 

So some photos of seven rear diffusers not installed on the car would be helpful.

[supersportsp]

Now that I think of it, I believe the S3 R500 Superlight does have the ducted nose.....now if someone could just solve the problem of excessive heat buildup in the engine bay caused by the redirected airflow through the nose and not through the bay, a ducted nose would be all gain and no pain.

 

That is correct. It has the ducted nose and the winglets of the CSR. I would have thought they would have used the CSR style cycle fenders as well on this car. Obviously, it is a little more difficult to fit the inboard suspension on the S3 chassis.

 

http://farm4.static.flickr.com/3459/3363594410_36f873b54c.jpg?v=0

 

I imagine if you wanted to go whole hog on an S3 chassis you could do the following:

 

-R500 ducted nose

-Winglets

-CSR style cycle fenders

-Aero wishbones

-Lowered and/or smaller headlights

-Wind deflector vs. windshield

-Freestyle inboard suspension for S3 chassis

-Rear diffuser

-Hard tonneau cover for passenger space and half door on driver side

-CSR front splitter (shortened width wise to fit S3 nose)

-Underside engine bay cover

-Rear diffuser

-Hard boot cover

 

As Se7ens go, that is probably about as slippery as you can get.

Edited December 1, 2010 by supersportsp