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PostPosted: Wed Feb 20, 2013 5:50 pm 
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Joined: Mon Jul 30, 2012 10:33 pm
Posts: 39
I'm enjoying this discussion, as I'm looking for a race wheel for crits and flatish road races. I have been focusing on the 60mm +/- profile. Zipp, Enve, etc are out of my price range. Also considering the Williams System 58. Any other alternatives would be greatly appreciated. It would seem most in this class are in the 1600g+ range?


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PostPosted: Thu Feb 21, 2013 1:18 am 
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in the industry

Joined: Wed Oct 31, 2007 10:45 pm
Posts: 339
Location: Indianapolis
BobDopolina wrote:
So ZIPP says that anything that varies from their patented shape by even a fraction of a mm isn't worth the effort?

I wonder what NASA thinks?


There's a reason our CFD iterations and subsequent wind tunnel prototypes often vary in width or location of maximum width by .25-.5mm, and it's not because we like spending a bunch of money on prototypes and days waiting on CFD solutions. :roll:

Radii similarly vary by small amounts as well.

As we were moving to what became the Firecrest and before our CFD development was fully fleshed out, I had an 808 profile that was quite close to where we our now. I was pretty proud of it, but in the tunnel it was within 5 grams of the old 808 at every data point. :oops:

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ENVE contract engineer | Former Zipp test engineer


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PostPosted: Thu Feb 21, 2013 2:07 am 
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Shop Owner / Manufacturer

Joined: Thu Jan 24, 2013 8:48 am
Posts: 103
Location: Taiwan
Waldo wrote:
There's a reason our CFD iterations and subsequent wind tunnel prototypes often vary in width or location of maximum width by .25-.5mm, and it's not because we like spending a bunch of money on prototypes and days waiting on CFD solutions. :roll:

Radii similarly vary by small amounts as well.


Right, because we all know there is only one answer http://www.ae.illinois.edu/m-selig/ads/coord_database.html to any question.

_________________
BDop Cycling Co., Ltd.
www.bdopcycling.com


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PostPosted: Thu Feb 21, 2013 2:55 am 
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in the industry

Joined: Wed Oct 31, 2007 10:45 pm
Posts: 339
Location: Indianapolis
There's lots of answers, particularly when you consider drag, side force, center of pressure, and shedding frequency, among others (not to mention that the rim profile needs to function as a leading edge as well as a trailing edge). Some answers happen to be much better than others. Hence the iterative process I mentioned. :D

There's also some much more useful sites for examining the more well-known airfoil options, particularly those that are demonstrably more appropriate for the Reynolds numbers typical of the flow regime in which we operate. Here's one that's much more searchable if you know what you're after:
http://www.worldofkrauss.com/foils/search" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

In the meantime, perhaps we should let this thread return to topic...

_________________
ENVE contract engineer | Former Zipp test engineer


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PostPosted: Thu Feb 21, 2013 4:52 am 
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Joined: Mon May 30, 2005 7:13 am
Posts: 1536
This looks like a decent one to try with a process I talked about earlier:
http://www.worldofkrauss.com/foils/1340

My half baked wheel design process:
viewtopic.php?f=3&t=103936&start=30#p949126

What do you think Waldo, care to hire me? haha


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PostPosted: Thu Feb 21, 2013 5:09 am 
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Shop Owner / Manufacturer

Joined: Thu Jan 24, 2013 8:48 am
Posts: 103
Location: Taiwan
Waldo wrote:
In the meantime, perhaps we should let this thread return to topic...


Agreed.

BTW, thanks for the link. I'm familiar with that site but I used the one I posted because it was far more dramatic - like the black marble slab in 2001...

I think it's pretty clear who sets the bar in the industry and thanks for being a sport while I bust your chops about it. smilie face.

_________________
BDop Cycling Co., Ltd.
www.bdopcycling.com


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