Rember the intake port texture debates?

[bigblockmopar]

Let's try this again.
Any thoughts on what might be happening here? https://www.youtube.com/watch?v=zl7jk85D2sE

You mean, besides the seamingly perfect streamlined belly @ 0:11 ?

[MadBill]

Well for one thing, they've got the smoke wand in the wrong place when they're checking the front fender air extractors. They should be going into the wheel well to see how well they evacuate the area..
There's a ton of info to be had by watching where the smoke stream goes. For example, being at ~ 0° incidence to the ground, the un-cambered wings would appear to produce zero downforce, but from the smoke path it's clear the air is turning perhaps 10° down over the rear window, so the effective incidence is 10°, probably getting up near the stall point of such a basic airfoil.

[The Radius Kid]

I'm thinking around the 2:20 mark forward.I know if a dummy like me can see it...........

[MadBill]

I believe they're exploring the point at which the airflow down the rear glass detaches from the surface and forms vortices.

[The Radius Kid]

Exactly Bill.It looks like the air is reversing back up the glass to try and fill the void.

[GARY C]

Exactly Bill.It looks like the air is reversing back up the glass to try and fill the void.

I was wondering if that was due to the down force on the deck lid they were trying to create?
I also noticed the front end sits way in the air and wondered if it drops at speed due to down force?
If so I don't think they are getting correct readings without pulling the car down to ride height.

[The Radius Kid]

Exactly Bill.It looks like the air is reversing back up the glass to try and fill the void.

I was wondering if that was due to the down force on the deck lid they were trying to create?
I also noticed the front end sits way in the air and wondered if it drops at speed due to down force?
If so I don't think they are getting correct readings without pulling the car down to ride height.

To be honest Gary,the main thing i was focusing on was the back window part.
That reversing air got me thinking.

[bigblockmopar]

Aside from the 'Daytona'-models, in '69 Dodge brought out their Charger 500-model, which had the rear window 'bulged' inline with the roof, compared to the regular Charger-model, where the rearwindow is recessed way back.




The '71 Plymouth rearwindow angles down to steeply and is too flat for the airflow to stay attached.
I would think if Plymouth had actually brought out a '71 Nascar model, they would/should have mostlikely installed a more bulged window, like the pervious year's Superbirds had.

[Cubic_Cleveland]

Exactly Bill.It looks like the air is reversing back up the glass to try and fill the void.

I wonder what would happen if vortex generators were attached to the roof in front of the rear screen? Would the flow stay more attached on the screen and not reverse

[MadBill]

Like these? http://www.airtab.com/
I'll see if I can dig up the pix, but I fitted them along the back of the roof of a road race Merkur, initially on only one half, and put blobs of hand cleaner down the glass. The half with the tabs smeared the blobs down the slope; the other did not, clearing indicating that they 'steered' the air down the deck. At the time we didn't have the car well enough sorted to know if they helped and when it was repainted they were discarded..

[Cubic_Cleveland]

Like these? http://www.airtab.com/
I'll see if I can dig up the pix, but I fitted them along the back of the roof of a road race Merkur, initially on only one half, and put blobs of hand cleaner down the glass. The half with the tabs smeared the blobs down the slope; the other did not, clearing indicating that they 'steered' the air down the deck. At the time we didn't have the car well enough sorted to know if they helped and when it was repainted they were discarded..

Yes, either like those or the OEM Evo style : https://www.maperformance.com/products/ ... mz380295ex
Would be great to see some pictures, looking at getting some for my mx5. How steep is the Mercur rear screen? Did any of the blobs go up the screen?

[MadBill]

Here's a couple of shots of them*. (and my patented 3D tuft test yarns, which also showed the re-direction of the flow.) *(They're manufactured about 2 hours away from me in Canada, but we had to buy them from Wisconsin. Go figure.. .)

The blobs on the 'un-tabbed' side all stayed where they were placed, but on the side with the tabs the upper row moved down ~ 1", the second row ~1/2" and the lowest not at all.

Merkur Tuft Tests 001.JPG

Merkur Tuft Tests 003.JPG

[Cubic_Cleveland]

Thanks for the pics and explanation Bill, love the low tech aero rake too!! Where should I send the licence fee when I steal your idea?

[MadBill]

The Wright Stuff Home for Former Flyers in Dayton, Ohio would be happy to accept any contributions...