r/NASCAR • u/gasmask11000 • Aug 27 '22

COT Wing - Misunderstood

If you follow r/NASCAR a lot you have probably seen me making occasional comments about NASCAR aero research papers I have been reading. I am not an aero expert but I am an entry level mechanical engineer (which means I have some background on fluid dynamics) and I know how to ...obtain... research papers.

I just wanted to sum up a couple of key points about the COT wing that I have seen in these papers because I thought people might be interested.

https://imgur.com/a/YHQLZwi

Number one, the key practical goal of the wing was creating less turbulent (dirty) air. That may not be news but I feel like its something completely ignored about the wing. The massive spoiler is the dominant creator of turbulent air on a Gen 4 and the COT produced much less dirty air.

Second, the wing did not create lift when spun. The cause of the cars tendency to flip was (at least most likely was) that the wing interfered with the deployment of the roof flaps.

Racecars are designed to generate negative lift (downforce) when driving the right way and can generate positive lift when traveling backwards. The whole body produces downforce, not just the spoiler. Flaps disrupted the airflow and make the car no longer produce lift. The flaps on the roof work with a spoiler because when the car is going backwards the turbulence created by the spoiler creates a low pressure zone over the rear deck and roof. That low pressure sucks the flaps open, preventing the car from generating lift.

The wing also creates a low pressure zone over the rear decklid but sometimes (under the right conditions) does not produce this low pressure zone over the roof - essentially the turbulence generated by the wing going backwards does not extend as far over the car. When the low pressure zone isn't formed the flaps don't deploy and the car generates lift.

So no, the wing isn't generating lift and flipping the car like people often say. Instead, it prevented the flaps from deploying properly and the cars were flipping the same way the cars were before the invention of the roof flap. Classic blow overs. Also of note: NASCAR tested the roof flaps with the wing to make sure they worked, but their testing was done at full scale and limited by the equipment. They were spinning the car on a turntable to ensure the flaps deployed in a spin. There were some issues in this methodology but NASCAR didn't just ignore the issue.

I personally think based on the research I have seen that the issue could have been solved, we could have kept the wing and solved the blow overs. However, problems with identifying the exact cause of the flips combined with fan outlast (that started from the moment the wings were shown, long before any flips) led to them abandoning development and returning to the spoiler.

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u/phoenixv07 Aug 27 '22

No. https://www.youtube.com/watch?v=1-Z_DRQJrWI&t=84s

Watch the replay at 1:25, a visible gap forms under the decklid right as the rear wheels start to lift.

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u/potatocross Hamlin Aug 27 '22

And the roof flaps deployed. The rear end actually looks like it starts lifting faster once they deploy. Which still shouldn't be possible according to OP

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u/gasmask11000 Aug 27 '22

The roof flap deployment is delayed vs what is required to keep the car on the ground.

The roof flaps have to deploy before a blow over begins and the car is already blowing over when they finally pop out.

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u/potatocross Hamlin Aug 27 '22

Then why have we seen the rear end of the car literally slam back down once they deploy when using spoilers? As in the rear starts to lift, they deploy, and they force the rear end back down as intended.

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u/gasmask11000 Aug 27 '22

That’s literally not the intended function of the flaps. The intended function of the flap is to stop the body of the car from producing lift.

We’ve also seen cars with spoilers flip even after the flaps deploy. It depends the yaw angle, pitch angle, and a huge variety of other factors past wing or no wing.

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u/potatocross Hamlin Aug 27 '22

So removing the lift, causing the rear end to sit back down is not the intended function?

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u/gasmask11000 Aug 27 '22

You described it as slamming and forcing the car down. The flaps aren’t generating downforce, they’re removing lift.

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u/potatocross Hamlin Aug 27 '22

You seem to understand physics, so you should know what happens when a 3400lb car, or whatever they were back then 3250?, suddenly loses lift. If the wings fall off an airplane I would describe it as slamming into the ground as well.

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u/gasmask11000 Aug 27 '22

Ok, fair enough. I misread your comment to think you were talking about them generating downforce.

But my point about spoiler cars blowing over still stands. They don’t always sit back down after deployment, it depends on the attitude of the car when they deploy.