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 Post subject: Re: Streamline tubing
PostPosted: Thu Jul 14, 2011 12:48 am 
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Thanks for putting in some numbers, OrangeCrusader. My old FF was about 5 HP down on the good competition. Hmmm....

So is that change in drag true for airfolis even with a %50 section? That aero tubing doesn't seem super aero. I think some of the formula cars I've looked at just used tube flattened almost completely, I was surprised it doesn't buckle...

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 Post subject: Re: Streamline tubing
PostPosted: Thu Jul 14, 2011 1:13 am 
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horizenjob wrote:
Thanks for putting in some numbers, OrangeCrusader. My old FF was about 5 HP down on the good competition. Hmmm....

So is that change in drag true for airfolis even with a %50 section? That aero tubing doesn't seem super aero. I think some of the formula cars I've looked at just used tube flattened almost completely, I was surprised it doesn't buckle...


Just a matter of knowing the forces involved and giving yourself a reasonable Fos, those fsae cars do weigh 1/3 of most locosts, and you can bet most parts and sizes used wouldn't work well in anything much larger, Fos's of 1.2-1.5 approach 'too much' where every gram removed counts, you do see the odd components fail since they're being pushed to their limits, the margins get quite narrow.

For those #'s, the tubing would present the same area to the wind, but the round tube turns out to be kinda messy aero-wise, so the gains are notable when the shape changes to one that simply smooths the airflow coming off of it somewhat, even if it's not ideally aerofoil-shaped. Same reason that a locost has such an awful Cd, it can break through the air reasonably well, but the low pressure area it creates due to the shape tumbling the air coming off of the back literally sucks the car back at speed. Those Lola bits would likely see almost all the gain that a true aero shape would see, but are much easier to produce and more predictable and reliable in their performance than an asymmetric aerofoil, both important advantages as well.


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 Post subject: Re: Streamline tubing
PostPosted: Sun Nov 27, 2011 7:21 pm 
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Due to the high price of the aero tubing, why not just take the rectangle tubing, split some round, weld the half round to the front of the rectangle? ([]) ([]> You could weld the other to the back, but according to the Kamm theory, it probably wouldn't do much difference. The other idea would be half round on the front and a slightly squashed half-square tubing for the rear taper. I plan on trying it out if I have some extra 1" tubing lying around.

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 Post subject: Re: Streamline tubing
PostPosted: Mon Nov 28, 2011 8:13 pm 
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SteyrTMP wrote:
Due to the high price of the aero tubing, why not just take the rectangle tubing, split some round, weld the half round to the front of the rectangle? ([]) ([]> You could weld the other to the back, but according to the Kamm theory, it probably wouldn't do much difference. The other idea would be half round on the front and a slightly squashed half-square tubing for the rear taper. I plan on trying it out if I have some extra 1" tubing lying around.

...which kind of brings us back to the first page of this thread and ideas to "beautify" Jack's otherwise excellant LCA design. :)
It would be great to have an aesthetic improvement to square or rectangular sections that improved aero performance and didn't impact cost and weight significantly.
Please post pics of your test sections.

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