Rear kammback spoiler

[JulianEdgar]

Originally Posted by aerohead

*Until you understand the implications of what the local pressure is at the separation line on top of the Cayenne,and what it would mean to move that separation line all the way back to the rear of the car,there would be no point discussing the degree of lift it can telegraph over the rear of the car.I recommend a brush up on Bernoulli.

What separation on the roof of the Cayenne? Have you looked at the wind tunnel video with smoke streams produced by Porsche? Just as one would expect, it doesn't show any separation on the roof.

[freebeard]

Won't someone think of the OP, eagle, and take it elsewhere? I suggest the form of a rap battle.

Im guessing so the turbulent air can escape

My thought drift to the Merkur XR4Ti with it's biplane spoiler.


https://ecomodder.com/forum/showthre...tml#post267188

Just mounted at the top of the hatch and pancaked somewhat.

I know this is off-topic, but maybe those other two can take it off to another thread. I ran across it looking for a Merkur pic.

Behold, a fastback Porsche coupe with Template conformity, and a Coanda effect from the engine rear mounted heat pump.

[California98Civic]

Originally Posted by freebeard

... My thought drift to the Merkur XR4Ti with it's biplane spoiler.


https://ecomodder.com/forum/showthre...tml#post267188

Just mounted at the top of the hatch and pancaked somewhat....

I love that spoiler. I also suspect that the roof spoiler the OP is describing might not be so much to let air escape as it is for "tuning" the flow in some way. For example, Subaru apparently spent a lot of time and money tuning the position of those silly looking vortex generators you see on the STi from a fee years ago. The goal, I read, was to direct flow to the substantial wing on the rear decklid.

[JulianEdgar]

Originally Posted by California98Civic

Subaru apparently spent a lot of time and money tuning the position of those silly looking vortex generators you see on the STi from a fee years ago. The goal, I read, was to direct flow to the substantial wing on the rear decklid.

That was certainly the goal on the original Evo Lancer, and they did (according to Mitsubishi's modelling) work a bit.

Left with, right without:



It would be interesting to see the modelled pressures under the wing.

[j-c-c]

Originally Posted by freebeard

Won't someone think of the OP, eagle, and take it elsewhere? I suggest the form of a rap battle.


My thought drift to the Merkur XR4Ti with it's biplane spoiler.


https://ecomodder.com/forum/showthre...tml#post267188

Just mounted at the top of the hatch and pancaked somewhat.

"Biplane spoiler" or Hybrid aero device, or Wing supplemented with a spoiler, which can be rather dubious in that one can deduct effectiveness, depending on orientation to each other, from the other, unless cosmetic enhancement is the primary goal, in that it sells cars and earns profits, from the punters, IMO.

And I also don't see a lot of commonality with OP's pictured "guess" example.

[JulianEdgar]

Originally Posted by j-c-c

"Biplane spoiler" or Hybrid aero device, or Wing supplemented with a spoiler, which can be rather dubious in that one can deduct effectiveness, depending on orientation to each other, from the other, unless cosmetic enhancement is the primary goal, in that it sells cars and earns profits, from the punters, IMO.

And I also don't see a lot of commonality with OP's pictured "guess" example.

Yes, I have always wondered how this was supposed to work. Has anyone ever seen a tech paper on this type of design? It would be really interesting to see some tuft testing.

[freebeard]

I'll bet we could/should ask aerohead.

[MHR1294]

To OP

I had a 2001 Volvo V70 T5 which had a high mount spoiler with a "hole/slot" in it.

Interesting thing happened, you could see the giant swirls in the mirror generated when it was raining in the spray. You could see 2 big swirls forming on the rear window coming down from the upper middle an spreading out. So looking from the rear, that's clockwise on the left and anti-clock on the right.

With the hole covered up, the dirt left on the rear window was more uniform spread. Fuel consumption was a little bit worse too, however the scale only reads to the nearest 0.1mpg (imp) so 0.4mpg improvement might not be as significant when you take in other factors.

so, I don't know what it was doing, but it was definitely doing something.

Perhaps it's performing a similar function on the fiesta?

[JulianEdgar]

Originally Posted by MHR1294

To OP

I had a 2001 Volvo V70 T5 which had a high mount spoiler with a "hole/slot" in it.

Interesting thing happened, you could see the giant swirls in the mirror generated when it was raining in the spray. You could see 2 big swirls forming on the rear window coming down from the upper middle an spreading out. So looking from the rear, that's clockwise on the left and anti-clock on the right.

With the hole covered up, the dirt left on the rear window was more uniform spread. Fuel consumption was a little bit worse too, however the scale only reads to the nearest 0.1mpg (imp) so 0.4mpg improvement might not be as significant when you take in other factors.

so, I don't know what it was doing, but it was definitely doing something.

Perhaps it's performing a similar function on the fiesta?

Interesting. Trailing vortices that rotate (viewed from behind) clockwise on the left and anticlockwise on the right are indicative of the body developing lift.

[MHR1294]

Originally Posted by JulianEdgar

Interesting. Trailing vortices that rotate (viewed from behind) clockwise on the left and anticlockwise on the right are indicative of the body developing lift.

I think I got that right, it was in the mirror. If I still had the car I'd love to go and test it.

The droplets would run down from the upper middle of the screen, and spread towards the lower outer edges. So whatever direction that is!

The spoiler did angle down too, I'm sure I've got a picture of it somewhere I'll go have a dig.