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Old 05-28-2009, 06:01 AM   #46
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I had a set of front diffusers that had atteched to the front A-arms and also tried something that went under the front bumper, but I found that anything put on the front of the car causes understeer. As for the rear, it is more traditional style for touring cars with the upkick and canards,but they are not set to 0-degrees (strait in line with the chassis) They are angled slightly. I will be posting pics again in a few days after I have had a time to revise and do some more testing.
Thanks rcfoolz, Im really looking forward to the pics and want to give it a try at BumodGP next week, I read the efra book and there is nothing about underbody aerodynamics.

Do you make those diffusers from pieces of a lexan body?
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Old 05-28-2009, 02:50 PM   #47
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Thanks rcfoolz, Im really looking forward to the pics and want to give it a try at BumodGP next week, I read the efra book and there is nothing about underbody aerodynamics.

Do you make those diffusers from pieces of a lexan body?
The diffusers are made from flat lexan sheets.
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Old 05-29-2009, 01:50 PM   #48
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How does more downforce decrease tire wear? Doesn't more downforce mean more friction and more wear?
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Old 05-29-2009, 01:56 PM   #49
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How does more downforce decrease tire wear? Doesn't more downforce mean more friction and more wear?
If the car is loose, all that sliding will cause more tire wear. In this case, increasing rear downforce will reduce the sliding and reduce tire wear.

If the car was perfectly balanced in both a low and high downforce configuration, the low downforce set-up would usually have the lower tire wear due to lower corner speeds and less vertical load on the tire.
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Old 05-30-2009, 01:23 AM   #50
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When I was living in South Carolina, the local Red Necks talked me into running oval.

Back then I built an complete underbody cover from lexan with integrated diffusor.
It wokred great, I was actually able to remove the rear wing from the truck body.

The problem was, that this aero package was very hard to maintain.
I had the body and the cover connected with velcro and when everything was in place, it worked great but if anything came loose, the car was undrivable.

For this to work, you have to keep the air that goes under the car from circulating inside the body, but force it to stay under the chassis and go through the diffusor.
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Old 05-30-2009, 02:19 AM   #51
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When I was living in South Carolina, the local Red Necks talked me into running oval.
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Not to get off topic, but where did you race oval and when? I was in South Carolina up till about 2001 and was running Oval at The Grove, Carolina Connection, and 17A raceway (Racin Fools).. and sometimes we would go to Augusta.
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Old 05-30-2009, 02:47 AM   #52
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Not to get off topic, but where did you race oval and when? I was in South Carolina up till about 2001 and was running Oval at The Grove, Carolina Connection, and 17A raceway (Racin Fools).. and sometimes we would go to Augusta.
I raced in Easley (close to Greenville) from 1996 to 2004.
I also went to the Grove for sedan quite often and raced Nitro at the Sugarbowl near Atlanta.

So, do you know Jeff Helms and Chris Pace?
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Old 05-30-2009, 04:03 AM   #53
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If the car is loose, all that sliding will cause more tire wear. In this case, increasing rear downforce will reduce the sliding and reduce tire wear.

If the car was perfectly balanced in both a low and high downforce configuration, the low downforce set-up would usually have the lower tire wear due to lower corner speeds and less vertical load on the tire.
perfect explainantion for the first paragraph.

I don't agree with the 2nd paragraph. I think a high downforce setup would increase the life span of tires due to tire less sliding, and perhaps a little bit of less cornering speed. ...... maybe it's typo error ?
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Old 05-30-2009, 05:43 AM   #54
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OK let me change the question to make it more clear

Assume that you have almost the same traction without loosing grip. In terms of tire wear, do you want to get that traction with mechanical grip or aerodynamically? I mean which one will be harder on tyres? Lets say cornering high speed sweepers.

Lets say average race speed is 50kph in a wide-fast track. How much downforce can we get at 40kph? I don't think it will pass 25-30 grams.
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Old 05-30-2009, 05:49 AM   #55
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Mechanical traction is partly done by setting camber and toe-in. Both settings will create friction on the tires.

With aerodynamic grip you can keep these settings almost straight so the tires will have less friction.
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Old 05-30-2009, 05:59 AM   #56
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Mechanical traction is partly done by setting camber and toe-in. Both settings will create friction on the tires.

With aerodynamic grip you can keep these settings almost straight so the tires will have less friction.
Downforce creates weight. More weight makes more tire wear. To get the same results compared to mechanical grip tuned car, lots of downforce will be needed.

On the other hand less weight and more camber-toe.

I just wanna know which one will be easier on tires.
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Old 05-31-2009, 05:23 PM   #57
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james rcfoolz put one on my car today and let me tell you
IT WORKS and the tire wear was less with it then with out
it. on a loose track it's like night and day IT WORKS and if
everything goes well for james you guys may have it to try
on your car KEEP UP THE GOOD WORK JAMES RCFOOLZ


IT WORKS
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Old 05-31-2009, 07:22 PM   #58
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I don't agree with the 2nd paragraph. I think a high downforce setup would increase the life span of tires due to tire less sliding, and perhaps a little bit of less cornering speed. ...... maybe it's typo error ?
No typo, again I said with a perfectly balanced car and I would assume perfect driving. Lower downforce means less grip and (if driven appropriately) lower corner speeds, less vertical load on the tire and therefore less tire wear. If you overdrive the car and slide it around like crazy your tire wear will go through the roof. So yes, in the real world of RC racing, more downforce will probably reduce tire wear but with proper driving, theoretically it should be opposite.
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Old 06-01-2009, 05:47 PM   #59
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Wanted to give some actual data on 3 racers running the Diffuser:
Manny Cosmo
quals without the device, 17laps 5:16.660 with a fast lap of 16.933.....
with it 17lap 5:06.456 and a fast lap of: 16.321.
The week before, we did the same test, again, the results were: fastest lap without 17.864 to a 17.307
ran 10.2 seconds faster and a faster lap by .609 seconds

Randy Smooth:
fastest lap with out the diffuser:17.167 fastest lap with: 16.668
qualifier with was an 18lap 5:12.504 and without it: 17laps 5:04.057
ran 8.43 seconds faster and a faster lap by .499 seconds

myself:
fastest lap without it: 16.018 with: 15.626
qualifier was with: 19laps 5:08.294 and without it was 19laps 5:15.972
ran 7.678 seconds faster and fastest lap by .392 seconds

This test was done with using 2 devices between 3 cars. Different setups, different driving styles and different times thought the day, so it was about as fair as I could get it.
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Old 06-01-2009, 06:02 PM   #60
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Was looking at something here: In the results, I took the time difference between fastest laps and mulitplied them by the total number of laps in the fastest qualifier: Justthought that the results were a little supprizing:

Manny had a difference of .609 seconds X 17 laps = 10.353 seconds
His faster qualifier was by 10.2 seconds

Randy had a difference of .499 seconds X 18 Laps = 8.982 seconds
His faster qualifier was by 8.43 seconds

My difference was .392 seconds X 19 laps = 7.448 seconds
my faster qualifier was by 7.678 seconds
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