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Discussion Starter · #61 ·
AND THEN AFTER ALL THE EFFORT, METICULOUS ATTENTION TO ACCURACY OF H, W, L, ANGLE, SLOPE, OFFSET, AERODYNAMICS TO THE MICROMETER, ETC AND EXQUISITDLY PERFRCTLY ALIGNED INSTALLATION... I DONT SEE THAT SPEEDBUMP JUST ONE TIME AND THAT SOUND FROM MY UNDERBODY IS 100 TIMES WORSE THAN NAILS DOWN A CHALKBOARD...NEXT THING I KNOW THEYRE CHECKING ME INTO BELVUE PSYCH WARD, LOLOLOLOLOLOL!

But liksly more truth to that than Id like to admit were this my project!

AD ASTRA PER ASPERA

From a native Kansan!!!

And the best of success to you realizing the fruition of the dream for all you've invested!!!

Peace
What the hell would I be doing anywhere near a speed bump? If you recall, the second round of testing on V1.0 was driving purposefully over entry/exit driveways and parking lots to determine the strike potential which is why I took 1 inch off for V2.0.
 

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oldmaninsaline said:
back in the 1970s right after we invented the wheel (we need the wheel to move that other thing we invented, fire) Yes, road racing aero can cross over but there's not enough beer in the world to convince me to put a 3 foot lip or a kitchen counter mounted on broomsticks on my Stealth.
Still reading through your thread but got to this and damn near lost it.

oldmaninsaline said:
Which is why when someone opens their pie hole and says it could always be worse they wind up waking up looking at the lights (an old hockey term, think Bob Probert. Good friend of mine is Dave Shand, another enforcer. Man, do I have some stories.). Speaking of which, the night the Wings chased old Roy off the ice and he quit the Canadians was the highlight of my life.
And a hockey fan to boot. Nice.

Eventually I'll aero my car to try to up MPG. Then again, a tune might make my 12-14 MPG get better too.


Sent from my HD1907 using Tapatalk
 

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Discussion Starter · #63 ·
Well, that's weird. The car is in the shop - Larry's going to call when they have it on the lift so I can shoot some video not on my back. And I finished V2.0 up this afternoon.

Later, I'm going to shove some baby powder down my pants and pretend it's coke while channeling Probert. My best sports memory is when the Wings chased Roy off the ice. Epic.
 

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Discussion Starter · #64 · (Edited)
An update on the diffuser V 2.0. The diffuser, at long last, is now on the car. At this point, I'm ready for yet another round of tuft testing and probably some flow vis tests as well now that it's warm enough to do that.

After the two rounds of testing without the strakes and with and without the barge boards, I'm ready to start testing with the strakes and the vortex generators (as far as I know, nobody else has done it quite this way because of sanctioning body rules and whatnot). I'm pretty sure some manufacturer somewhere while building a super or hyper car has used vortex generation in a diffuser but finding information about that is near impossible. There have been, however, scientific papers on the subject. This is called "force enhancement of an underbody diffuser" which as a point of interest related directly to roof vortex generation and wing style spoilers. And that means I get to learn abou the exciting world of "Reynolds Averaged Navier-Stokes equations with a turbulence model and wall functions using the SIMPLE algorithm "


The thing with the strakes that's interesting is not only the vortex generation along the edges but the venturi effect of the strakes and their angles (which is where the thickness of the strakes comes in). What I've learned is that a 5 degree angle on the strakes (end to end not top to bottom) makes all the difference in the world. Most road cars are in the "thereabouts" class when setting up aero so getting into the 5 degree and doing the related math (X angle over Y length) can get sticky. This one worked out to 9/64 of an inch.

Before I can even think about doing the testing I need to noodle out the barge boards to get enough air into the diffuser for it to work correctly. The barge boards need to stand off from the body kit for clearance purposes and that's where the hangup is. For some reason, the material isn't responding to bonding layers together. No matter what I use or how I prep the surfaces, they keep breaking apart. I could take a shortcut called Gorilla Tape and nobody would see it but I'd know it was there and it would bug the shit out of me.

Now I'm thinking riveting instead of bonding the barge board parts together. That would mean finding rivets that will bond 1/4 inch of material.
 

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My other two threads :
First thread:
Second thread:

. My front air dam sure seems to work well. I styled it after the 3000gt active when it's extended. Yeah, it rubs sometimes but I designed it to be flexible. The last time I went to the cabin, 75 all the way, 21 mpg. So it's doing something under there.

What I've learned about diffuser design is overwhelming. I had no idea how much work goes into them. I'd have to see what's under the twin Z. But it's almost simple. The strakes are designed to prevent air from the tire rotation entering the air stream from under the car. Any vortex generation is at the bottom of the strake:
| < strake
^ <vortex

But as far as the strakes go, this is what they do:
  • Strakes don't straighten the flow
  • Strakes aren't vortex generators
  • Tire Squirt and the real reason behind strakes
  • Managing floor vortices
So when you see those diffusers on sites like Carid or Amazon, they're for looks. Unless they're interrupting the air from the tires, they aren't working.

As Kyle has said in his videos, he worked on the Mercedes F1 team and he's run his diffuser information past an "unnamed" F1 aero engineer (I would suppose on the Mercedes team) about what exactly the strakes on the diffuser do and it isn't what I thought at all.

Well, I'm putting this on the first post on all three threads.
The guy that owns Kyle Engineering worked from 2018 to 2020 on the Mercedes F1 team doing aero design. As such:

I have located several 3D 1st gen models of various detail. The best one will cost me a hundred bucks or so.
I've talked with Kyle and he's willing to do CFD work for us!
I've got to have a more in depth conversation with him to add the aero bits I'm working on to the 3D model.
Your your diffuser is first-rate ............ Great job.

Dennis
 

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Discussion Starter · #66 ·
Your your diffuser is first-rate ............ Great job.

Dennis
Thanks Dennis. Right now I've got some deep cycle batteries and 30 gallons of water for the tiny home project so I don't have it on the car - that weight drops the back enough that the thing scrapes a lot. I'll have it on the car next week sometime for the next round of tests.
 
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