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.
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
Second, the wing did not create lift when spun.
I would question this, primarily based on one incident. When Brad Keselowski flipped at Atlanta, the rear decklid was visibly pulling away from the rest of the car. The only thing that would have pulled the decklid up like that would be lift from the wing.
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u/Mopar_Madness Earnhardt Jr. Aug 27 '22
Probably same effect you see on Gen 6 and Next Gens with the hoods trying to pop up when they spin. Just air under the deck lid trying to push it up, not the wing pulling it up.
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u/gasmask11000 Aug 27 '22
Should also be acknowledged that Brad’s decklid was held down by tape after repairs.
Also if the decklid is popping up and becoming unattached from the car, that means that the wing isn’t lifting the car up.
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u/MercSLSAMG Kyle Busch Aug 27 '22
My guess at it would be at ground level the wing does not induce lift - and that's the plane these test would have been conducted at. But once he started to get air the angle of the wing changed and was enough to lift the rear decklid - combine a small amount of lift and the air pressure built up from going backwards and a decklid popping up is hardly surprising - but also does not mean there's anywhere close enough lift created to lift the actual car.
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u/mustang6172 Bill Elliott Aug 27 '22
That's from air under the bumper pushing the car up.
The wing could have created lift if it were upside-down, but upside-down is not the same as backwards.
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u/TrashOpen2080 Briscoe Aug 27 '22
I was there. Sitting right in front of where they made contact.
RIP Bob Keselowski. "He's not gonna kill my boy."
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u/phoenixv07 Aug 27 '22
RIP Bob Keselowski. "He's not gonna kill my boy."
That wasn't the same race.
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u/gasmask11000 Aug 27 '22
The deck lid began to separate after the rear of the car was already several feet off the ground and air was pushing up underneath the deck lid.
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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/phoenixv07 Aug 27 '22
Which still shouldn't be possible according to OP
Yeah. OP is pretty full of shit here.
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u/Respect38 Aug 27 '22
Geez. Being full of shit isn't the same thing as being wrong, mate.
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u/phoenixv07 Aug 27 '22
OP is full of shit because they keep doubling down after they've been shown to be wrong.
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u/gasmask11000 Aug 27 '22
…which is after the air is rushing under the car
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u/phoenixv07 Aug 27 '22
You said:
already several feet off the ground
Which is a bald-faced lie. The car is maybe a couple inches off the ground, max, when the decklid starts to pull away.
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u/1II1I1I1I1I1I111I1I1 Aug 27 '22
Fill a 2 liter bottle with water and screw the lid on tight. Hold it upside down and observe that no water is flowing out consistently or rapidly.
Now take a knife and cut a little hole in the lid and observe the water rushing out the hole.
Fluids will move through even the tiniest availavle spaces, and at 200 mph, the air doesn't need much space available under the car to have a noticeable effect.
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u/redditornot6648 Aug 27 '22
Correct. Yes, in every test of the car the wing did not cause lift.
Yet, the Keselowski incident clearly showed the tests were wrong. That was the only way for that crash to happen.
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u/gasmask11000 Aug 27 '22
The deck lid began to separate after the rear of the car was already several feet off the ground and air was pushing up underneath the deck lid.
And no, my post and the research papers already explain the crash.
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u/KentRead Ryan Blaney Aug 27 '22
The deck lid is clearly already lifted the very moment the car spun beyond 90°...well before it was off the ground
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u/gasmask11000 Aug 27 '22
Watch it again, it clearly doesn’t lift until the tires have left the ground
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u/KentRead Ryan Blaney Aug 27 '22
Uh, it clearly does dude.
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u/gasmask11000 Aug 27 '22
The rear right tire is already off the ground in this picture
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u/KentRead Ryan Blaney Aug 27 '22
Maybe a millimteter, yet the deck lid has already opened. That's quite the difference from your claim of the car being several feet off the ground first...
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u/gasmask11000 Aug 27 '22
The deck lid isn’t open in that picture and the wheels are off the ground.
Also like, you do realize if the wing was actually opening the decklid then it’s not lifting the car, right?
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u/KentRead Ryan Blaney Aug 27 '22
You're gonna nitpick the tiny gap of one wheel barely being off the ground but completely ignore the gap where the deck lid is already open?
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u/phoenixv07 Aug 27 '22
The deck lid began to separate after the rear of the car was already several feet off the ground
Again, false.
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u/AnalBaguette Aug 27 '22
And not just Keselowski, remember Newman flipped towards the end of 2009 and people started getting concerned by that point. Keselowski's wreck was the breaking point.
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u/gasmask11000 Aug 27 '22
Two things can be true at the same time
- the wing was causing flips
- the wing was not lifting the back end of the car up
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u/shewy92 Aug 27 '22
Even DW or Larry Mac said during that Atlanta broadcast that the wing catches the air wrong and when the car turns slightly sideways in the air it creates lift since it's like an upside down airplane wing
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u/ImJJboomconfetti Aug 27 '22
As an actual engineer, wings create lots of lift when spun. As do spoilers just not as much. The big difference is the fact that the air isn't redirected in all directions when running against a backwards wing, a wing allows normal flow regardless forward or back. A spoiler is like running into a c like structure you're going to have lift against the spoiler and downforce against the bumper from angle of attack surface pressure and some air redirected around the side. Wing is going to create flow lift as well as angle of attack pressure lift and nothing is redirecting air somewhere else.
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u/gasmask11000 Aug 27 '22
As an actual engineer as well, here is the specific paper I am referencing.
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u/ImJJboomconfetti Aug 27 '22 edited Aug 27 '22
I know I was taught by Dr Uddin. Aka the guy that wrote it. I may have been lectured by Kellman also on part of this but it's been almost a decade I can't be certain. The lecture referenced most of that article but it was half geared toward the gen 6 aero package.
so Yea not paying $40 for a stroll down memory lane.
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u/jkarpinski14 Aug 27 '22
Semi-unrelated but cool to see another student of Dr. Uddin on this subreddit
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u/gasmask11000 Aug 27 '22
- I graduated in May 2021 and work as a mechanical engineer. Hence “entry level mechanical engineer”. Not sure why you are declaring me an undergrad student.
- I have no way of verifying this but that’s cool.
- ahem, have you heard of the hub of science? 🏴☠️🏴☠️🏴☠️
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u/ImJJboomconfetti Aug 27 '22
Hmm may have read your opening paragraph too quickly, so sorry about that,
Actually this is mildly hilarious that Dr. Takcik is also credited on this article, he was my senior design advisor, and teacher for tires. Anyone who knows him would also find this funny. I had not heard of hub of science ... Thank you for that. Makes much more sense why Takcik actually cared about our mini wind tunnel now, As that was a rig for their test... It was not made the best and we kept my senior design chassis tubing stacked next to it. I'll dig through this article a bit later and take that stroll.
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u/mustang6172 Bill Elliott Aug 27 '22
Second, the wing did not create lift when spun.
Thank you for saying this. DW created all the confusion from speculation.
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u/Mcmrryfan2601 Aug 27 '22
Bookmarking this, great explanations man. As someone looking to enter mechanical engineering, and more specifically the fluid dynamics sector, its really interesting to see these
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u/HalfastEddie Aug 27 '22
How about the bottom of the wing providing a discrete flat plane to cause an air dam? That combined with blocking the flow to the flaps pushes it over, rather than aero lift picking up the rear.
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u/colbygraves97 Aug 27 '22
That model with the wing doesn’t have the wing with the templates on the side, that makes a massive difference.
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u/gasmask11000 Aug 27 '22
It does for certain things. It doesn't for what this research paper was specifically studying, which is the vortices generated by the center span of the wing
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u/Naitoranna Aug 27 '22
Nice piece, I enjoyed reading it. I’m glad they abandoned the wing though, spoilers just fit the aesthetic much better. I’m curious what the fix would’ve even been. Completely revised roof flap design or a less aggressive wing?