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-   -   Ford Sierra XR4i Bi-Wing Spoiler? (https://ecomodder.com/forum/showthread.php/ford-sierra-xr4i-bi-wing-spoiler-39215.html)

JacobLeSann 03-20-2021 10:00 AM

Ford Sierra XR4i Bi-Wing Spoiler?
 
Hey all, do any of you have info/explanations of the aerodynamics behind the Bi-wing spoiler on the Ford Sierra/Probe III concept. I’ve read that it reduces drag, but I’ve also heard that it’s a measure for creating downforce. I’ve not found a concrete answer yet.

Snax 03-20-2021 11:26 AM

Just off-hand, looking at the angle of the back glass, the spoiler more than likely does reduce drag primarily by reducing lift. I've never seen an analysis of it on that car specifically however.

freebeard 03-20-2021 12:27 PM

Here is a site-wide Google search for bi-wing. https://ecomodder.com/forum/google_s...5679j6676099j7

It's not helpful to me because I have Prefs set to max number of posts per page instead of 20, and Google's search is page oriented.

Maybe you'll find something there. F1 front wings have gone away beyond bi-planar.

JulianEdgar 03-20-2021 11:43 PM

Quote:

Originally Posted by JacobLeSann (Post 644435)
Hey all, do any of you have info/explanations of the aerodynamics behind the Bi-wing spoiler on the Ford Sierra/Probe III concept. I’ve read that it reduces drag, but I’ve also heard that it’s a measure for creating downforce. I’ve not found a concrete answer yet.

It reduces pressure under the wing, so causing better flow attachment and allowing the rear spoiler to work better.

kach22i 03-22-2021 02:26 PM

Not the vehicle you requested, but adjacent?

Porsche 911 Ducktail - Study/Alternate
https://ecomodder.com/forum/showthre...e-36229-3.html
Quote:

Originally Posted by kach22i (Post 566227)
Below similar to the TV show Wheeler Dealer episode with the 1985 Ford Escort RS - Cosworth.

Was this:
VWVortex.com - So who didn't catch the Escort RS Cosworth episode?
https://res.cloudinary.com/carsguide...pa-%286%29.jpg

Now this:
Wheeler Dealers: S14 E1
http://www.motoringbox.com/wp-conten...t-cosworth.jpg

That middle wing shown above added 25 lbs of down-force in the wind tunnel, no idea how much drag it added though.


https://www.topgearbox.com/cars/ente...t-rs-cosworth/
http://forums.pelicanparts.com/uploa...1616437886.jpg

I don't remember if the "25 lbs of down-force" comment was from a video or post in that thread.

I do recall finding the Escort RS Cosworth when doing a search on the XR4i, so there may be common material in videos and articles floating around the Internet.

Piotrsko 03-22-2021 05:10 PM

Bet it's turbulent as sin back there.

aerohead 03-24-2021 11:34 AM

Cosworth
 
I think I posted on this car a decade or so ago. I suspect it's in my lectures.
From memory, it was a homologation special for rally racing. The rear addition provided downforce at the expense of lower top speed. 20- to-30 counts extra drag. Two-to-three miles per hour slower.
I'll try and find it.

19bonestock88 03-24-2021 11:58 AM

Interesting that this come up, I’ve considered a version of this for drag reduction on my Ion. Everything angled to reduce drag though

aerohead 03-24-2021 12:14 PM

explanations
 
Quote:

Originally Posted by JacobLeSann (Post 644435)
Hey all, do any of you have info/explanations of the aerodynamics behind the Bi-wing spoiler on the Ford Sierra/Probe III concept. I’ve read that it reduces drag, but I’ve also heard that it’s a measure for creating downforce. I’ve not found a concrete answer yet.

Lutz J. Janssen & Friedl W. W'u'lfing were the co-inventers.
If you can find a copy of United States Patent No 4,533,168, it has their full explanation.
I got mine off micro-film at the Dallas Public Library. It could be available online.

JacobLeSann 03-24-2021 04:32 PM

Thanks all. I’m still in search of a boat tail alternative, then. Still very interesting, and visually surreal.


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