^^ Did you read the Mitsu technical paper about vortex generators yet? Interesting stuff..
http://www.mitsubishi-motors.com/cor...004/16E_03.pdf

APR & Seibon have off-set angled fins like the UK OEM VG.. it's the Chargespeed, and it's replicas (Rexpeed, Spec-D, VIS) that have the larger fins that aren't angled properly.

And it's odd.. the OEM vortex generator is a factory option for any Evo X in the UK, not just the FQ400 (#SR012023), but it's not listed in the catalogs for JDM & USDM..

http://www.mitsubishi-cars.co.uk/evo...pe=56&group=29

 

Just to be clear: that's a paper on VGs for an 8/9. Those cars do gain from VGs on the roof, as shown. We need to find the paper for an X. It shows why VGs are not needed with the new roofline.

Why Mitsu offers them for UK cars is beyond me, but I do have a guess: it rains there more often and the VGs could very well help clear the rear window (since no X has a rear wiper).

 

^^ Yup. 2004 article was for 8/9 not X.

How about I buy an authentic UK VG, and you try and score me some tunnel time at Ames Research Center.. not sure which would be more difficult to accomplish

It would be nice if the VG actually helped clear rain from the rear windshield.. not even Rain-X seems to help that much in my experience.

 

I know that you were joking, but that actually isn't far-fetched. I'm a consultant for the National Advanced Driving Simulator here in Iowa City and my PhD advisor did his post-doc at Ames. And it would be more accurate than my normal approach: taping 50 little bits of string to the car and then driving around with a buddy filming me from another car. That's how I did the 2G DSM and I swore: never again.

 

^^ So it is easier to get into NASA, than to buy a part from the UK.. figured

From the other vids I've seen with tape & strings/streamers, they usually just have a passenger film the effect from inside. Seems easier than having a chase car.

 

[IMG][/IMG] [IMG][/IMG]

 

^That looks beast.

 

mine is rexspeed . Hold up well and i think looks good. i just love VG for the weird look they give for a car.

 

Does look good

Can't remember if I asked you before, but what CF rear spoiler is that?

 

This

(thanks, you saved me a lot of typing there!)

 

Sorry, my mistake!

You can just about see the off-set fins of the OEM VG in this photo:

 

I'm not one to pick on somebody, but I don’t want people to get the wrong end of the stick here.... so I have to let you know that you've got that a bit wrong.

The idea of the VG or to be more accurate, the turbulator, is to mitigate the production of a large vortex, by intentionally creating a series of smaller vortex. The net effect of multiple small vortex is significantly less than the drag effect of a large vortex.

 

While we clearly agree on what a VG does - i.e., by adding a small amount of turbulence now, you can delay when full-fledged flow separation happens later - from there our flows seems to separate, as it were. You are mixing in one of the possible net indirect effects with the one and only direct effect.

As I agreed earlier, one of the possible net effects of adding VGs can be to reduce drag. When truckers add VGs in front of their front wheel-wells, for example, that's what they're after. But there are times and places when and where adding VGs will actually increase total drag and there are reasons to put VGs on a surface that have nothing to do with drag. The best example of the latter is on small planes. Cessna's testing showed that adding VGs to the top side of the wings, near the leading edge, added drag, but the gains in airflow across the control surfaces - also known as not crashing the bloody plane - more than made up for this.

 

fair comment ....

PS just so you don't think I am a complete tool (that's the correct Americanism I believe), the upper deck on my diffuser is not an active part of the aerofloor on my car. Its actually for ACY and differential cooling, as well a method of achieving the correct angle at the lower deck.

 

No worries. I'm just happy to have a technical discussion. And you've caused me to think this issue through more carefully and moved me a bit from my previous position. For example, to the extent that you can decrease the velocity of the air moving down the rear window, you'll decrease drag. In some cases, that might be worth a small loss in the effectiveness of the wing.