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Old 07-28-2022, 10:13 PM   #11
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The world wouldn’t be in the state it is if they still printed sport compact car and grassroots motorsports. I miss how those magazines would consistently answer questions I was too dumb to think about asking.
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Old 07-28-2022, 10:26 PM   #12
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Originally Posted by street_rulerr View Post
one of my favorite quotes comes from dave coleman, engineer at mazda and former editor of sport compact car magazine...it goes something like

"air is generally invisible and impossible to predict. so we spent hours having uninformed conversations about whether or not this would work.

my personal take on predicting air movement, you can analyze it by the molecule or the cloud but whatever approach you take its gonna be wrong."
...and this is why we have a REV2, REV3, REV4, ect...

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Originally Posted by Deerhurst
What he is saying is the aerodynamics of a D21 is a brick in the wind.
Probably at least as bad as a Jeep so worse than a cow.
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Old 07-29-2022, 01:13 AM   #13
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...and this is why we have a REV2, REV3, REV4, ect...
With my budget enjoying the vehicle is priority #1 but making people who spent $80k on a car question their life choices is a close second though
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Old 07-29-2022, 06:18 PM   #14
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Just thinking it through I don't think it would be any advantage to have the wing mounted directly on the axle. It's going to make the same amount of downforce no matter where it's mounted. On top of that you're adding lots of unsprung weight to the rear which is going to do all sorts of negative things when hitting bumps. Think about having 500+ lbs of weight directly on your axle and you hit a bump. No imagine that happening when going around a curve...
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Old 07-30-2022, 03:07 AM   #15
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Just thinking it through I don't think it would be any advantage to have the wing mounted directly on the axle. It's going to make the same amount of downforce no matter where it's mounted. On top of that you're adding lots of unsprung weight to the rear which is going to do all sorts of negative things when hitting bumps. Think about having 500+ lbs of weight directly on your axle and you hit a bump. No imagine that happening when going around a curve...
You’re not wrong. I’ll see if I can work something out frame mounted but not set too far back, I’m not planning to go too deep into the suspension and I don’t want to do anything that’ll make the front end feel any more loose or disconnected. I have a front splitter/lip planned, and I’m prepared for some trial and error but the closer I get to good enough on the first try the more work I can save myself.
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Old 07-30-2022, 07:56 PM   #16
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...but the closer I get to good enough on the first try the more work I can save myself.
What, no version 2?

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Quote:
Originally Posted by Deerhurst
What he is saying is the aerodynamics of a D21 is a brick in the wind.
Probably at least as bad as a Jeep so worse than a cow.
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Old 07-30-2022, 10:08 PM   #17
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The difference is whether or not the suspension springs are loaded or the tires directly. the downforce when applied directly to the axke, is "un sprung" putting all the load into the tires. which if you cold balance the downforce (crazy ass front wing like a hill climb car + axle mounted wing) it would work well. youd need less downforce and therefore less drag to get the same force on the tire/tarmac.





I presume race teams dont do this because none of the suspension components on a modern design can handle that kind of force without breaking. picture a a-arm for a sec and imagine 500lbs chillin on one of those wee arms. you hear that sound? its the sound of metal snapping at 145mph on the back straight.
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Old 08-04-2022, 04:00 PM   #18
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Quote:
Originally Posted by 89'HBV6 View Post
What, no version 2?
There might be a “version 2” for specific parts but the whole truck is a proof of concept for my funky ideas so I figure upon completion it’ll still technically be “version 1” and the sooner I can say “done” the better because there’s a ‘65 ford f100, a Toyota fj40, 4 air cooled vw’s and a golf kart out back waiting for their attention.


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Originally Posted by street_rulerr View Post
The difference is whether or not the suspension springs are loaded or the tires directly. the downforce when applied directly to the axke, is "un sprung" putting all the load into the tires. which if you cold balance the downforce (crazy ass front wing like a hill climb car + axle mounted wing) it would work well. youd need less downforce and therefore less drag to get the same force on the tire/tarmac.

I presume race teams dont do this because none of the suspension components on a modern design can handle that kind of force without breaking. picture a a-arm for a sec and imagine 500lbs chillin on one of those wee arms. you hear that sound? its the sound of metal snapping at 145mph on the back straight.
Excellent insight thank you! I won’t abandon the axle mount idea just yet, but
I can’t rule out what PaulC said either so for now I can at least plan out a few different tests and see what happens.
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Old 08-04-2022, 08:00 PM   #19
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500lbs on an a arm? Probably more like 50,000lbs when you hit a pothole at 70MPH.
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Old 08-04-2022, 09:47 PM   #20
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Quote:
Originally Posted by Deerhurst View Post
500lbs on an a arm? Probably more like 50,000lbs when you hit a pothole at 70MPH.
Took this quote from a guy with degrees in aeronautics:

”To add appreciable amounts of grip to one end of a car, it would take an extra 10 percent of downforce relative to the weight of the car to notice any benefit at all. For a 3000 pound car (which is rather light for a street car) with a rear wing with a 2 square foot area (which would be a rather large wing on a car) generating an effective lift coefficient of 1 (which represents a nearly stalled wing at high angle of attack with a good amount of camber), it takes about 63 feet per second or about 42 miles per hour to get to 300 pounds of downforce, so I would consider that to be the absolute theoretical minimum effective speed. However, since most cars with wings are heavier, and have much smaller, less aggressive wings, you’re probably looking more along the lines of 80–100 miles per hour before you start seeing any benefit.”

The truck will be under 2k lbs (I think) when done, so the amount of downforce I -need- will be reduced and if I keep it on the track (like I’m supposed to) I won’t have to worry too much about potholes
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