Flappy Endplate for Sideways Downforce?

The really fast guys in rally tend to point out that a lot of the aero grip goes away if you get too sideways- recent ARA rule changes have really clamped down on diffusers and side winglets and such, so I thought of this idea for the rear wing endplates.  Please try to ignore the actual geometry here, it's just a quick sketch.

Straight line or minimal slip angle, everything normal:

But with a little hinged panel, maybe when you get sideways it works like one of those Z shaped sprint car wings?

I assume this doesn't work or I would have seen it somewhere.

Maybe the reason you don't see it it most sanctioning bodies have rules against "moveable aero devices".

The idea is not crazy. One thing that is not included in your discussion is the aerodynamic effect of sideforce, basically the same sort of restoring force for yaw that you see with downforce. It is something that has been part of the calculations for a few decades.

In reply to stafford1500 :

Presently, "movable" is legal but "cockpit adjustable" isn't, which is part of what led to this concept.

I assume the dumbed down way to maximize sideforce would just be giant endplates and maybe mid-width shark fin type things?

In reply to stafford1500 :

Depending on the rules, I wonder if something similar to radiator shroud flaps would be permissible.

You'd have to come up with a reason as to why those weren't aero parts, though

My concern would be if the panel ever accidentally lifted when driving with a little yaw. Saw a stray flutter causes the air over the top of the wing to catch the bottom of the flap and lift it up, you'd have a massive and sudden loss of downforce. Not just from the missing endplate but now the big, flat panel sitting across the top of the wing.  You'd need a pretty hefty spring holding it shut, but the slightest opening would go all the way open. Get the spring too stiff, and the flap won't open until it is too late to do anything. If it doesn't open until the car is beyond catching, it is no bueno. Getting that just right would be very, very hard. 

The other negative (and I'm not trying to be negative other than to brainstorm an answer to "why have I not seen this before"), is that large endplates can fight yaw as stafford said. When the flap opens, I am not sure which is better - the yaw-fighting ability of large endplate or the poor airflow diagonally over a wing. End plates can  help straighten the airflow a little, so even at small yaw angles, that opening may make things worse than better. Sprint cars operate at yaw angles way higher than any track car will, so their wing tech doesn't carry over 1:1 

This best shows what drift cars *were* doing for endplates to help with high speed stability. This picture best shows them since the made large clear endplates.

Full article here: BEE*R Drift Skyline

Maybe pulling some ideas from other motorsports couldn't hurt? Especially one designed in being sideways and changing directions at speed. I don't know if this is still done, but being clear wouldn't be easy to see in most photographs and tire smoke. 

In reply to DjGreggieP :

Interesting- I wonder how much of that is the tailfin sort of effect of just having more surface area for air to hit, vs. actually trying to keep extra air coming over the side of the car from sneaking under the wing.

In reply to ¯\_(ツ)_/¯ :

I *think* in the 'Outsiders: Japan' video (youtube linky) they explain the why better than the article, but I haven't watched my DVD in a long time, just remembered seeing it all that time ago. 

Bumps. Flaps have inertia, so whatever effect might be pretty unstable over anything uneven, right?

Might be worth looking into bike aero wheel and frame design. Lots of effort at minimizing drag from off-center air flow. Cliffs from what I remember is that maybe your uprights should be more of a rounded profile in plan.

Wheel profiles:

¯\_(ツ)_/¯ said:

In reply to stafford1500 :

Presently, "movable" is legal but "cockpit adjustable" isn't, which is part of what led to this concept.

I assume the dumbed down way to maximize sideforce would just be giant endplates and maybe mid-width shark fin type things?

What if the wing moved with the steering wheel, like bmw headlights?

Is that cockpit adjustable?

All joking aside, remember that air moved in 3d. The "side view" airflow may actually be less important than the "top view".

What about a wing shaped like a v instead of a straight wing? Yes you'd lose area when sliding but you could work the angles so you gain angle of attack. Then maybe at the center use your hinge idea on a vertical "endplate" that makes an endplate at the nose of the v when sliding?

Here's a question - Do you need the top half of the endplates?

I ask because most of the downforce from your rear wing comes from the underside. That and top level rally teams have been migrating to a wing design that droops down gently on the sides and has a long, flat bill underneath it. Kind of like this: 

If you look closely, the endplates are wider at the rear of the car than they are towards the front. That will help keep the wing working even when the car is in yaw.

Alternatively, do the ARA rulemakers care if you force the point? Because you can go the other way and put a lot of vertical strakes on your wing to straighten the flow. The solution worked reasonably well on the Subarus in the mid-2000's, and it's made a comeback this year on the Rally1 cars:

I know some ARA cars already have these quad strakes (e.g. the Subarus), but they're only on the top side of the wing. The Rally1 Toyota does this using four, very wide swan neck mounts, which act to forcibly straighten the flow as it goes back there.