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Main
Date: 30 Mar 2007 18:07:19
From: John Forrest Tomlinson
Subject: wind tunnel
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http://www.nyvelocity.com/content.php?id=1300
--
JT
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Remove "remove" to reply
Visit http://www.jt10000.com
****************************
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Date: 03 Apr 2007 07:52:47
From: Kevin Tuttle
Subject: Re: wind tunnel
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On 31, 11:49 am, Fred Fredburger
<FredFredbur...@WhereAreTheNachos.huh > wrote:
> John Forrest Tomlinson wrote:
> >http://www.nyvelocity.com/content.php?id=1300
>
> Where can I order one?
Did you guys ever hear of Photoshop? Why does the structure have to
be off the ground and can the supports really support it? Look a
little closer at the imagery.
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Date: 03 Apr 2007 05:32:55
From: Qui si parla Campagnolo
Subject: Re: wind tunnel
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On 31, 9:20 am, "Bill C" <tritonri...@verizon.net > wrote:
> On 31, 2:11 am, "Robert Chung" <m...@address.invalid> wrote:
>
> > John Forrest Tomlinson wrote:
> > >http://www.nyvelocity.com/content.php?id=1300
>
> > It's rekably cool what some guys will go through to avoid doing a little
> > math.
>
> Ya know for some people out here when you run out of fingers and toes
> the answer becomes "Many" or "A whole bunch.".
> Bill C
Most guys can only count to 20, 21 when naked.....
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Date: 02 Apr 2007 11:22:54
From: Andy Coggan
Subject: Re: wind tunnel
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On Apr 1, 1:22 am, "Robert Chung" <m...@address.invalid > wrote:
> Dan Connelly wrote:
> >> I think Coggan talked about doing something like that in the past.
> >> IIRC, he seemed to think the precision was poor.
>
> > Allen & Coggan is pre-IBike, but discusses using power for
> > aerodynamics without a wind gauge: just after dawn, to minimize wind,
> > ride a route in each direction, and do a regression of power/v versus
> > v, with intercept Crr, and slope CdA/2, with power measured with a
> > PowerTap to avoid drivetrain losses.
>
> Yeah, and I have my doubts about that method. Windless is important, but I
> think you'll get poor precision unless you take into account accelerations.
That point is discussed in the book (as is the need to start and end
each run on a banked track on the straight and not in the turn).
> However, I was referring to something else: Andy wrote somewhere or other
> that when the iBike came out it reminded him of an experiment he'd done with
> an on-bike wind gauge and on-bike power meter sometime before in an attempt
> to estimate CdA.
We never got our device working well enough to ascertain the
"workability" of the approach itself.
Andy Coggan
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Date: 02 Apr 2007 08:01:41
From: Bill C
Subject: Re: wind tunnel
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On Apr 2, 10:53 am, Curtis L. Russell <cur...@md-bicycling.org > wrote:
> On 31 2007 08:20:10 -0700, "Bill C" <tritonri...@verizon.net>
> wrote:
>
> >Ya know for some people out here when you run out of fingers and toes
> >the answer becomes "Many" or "A whole bunch.".
> > Bill C
>
> And some make up a number and then argue to the death defending it.
>
> Curtis L. Russell
> Odenton, MD (USA)
> Just someone on two wheels...
Is that why we don't see more pictures of Bush with his shoes off??
(Joke! Alert for theHumor impaired )
Bill C
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Date: 02 Apr 2007 17:18:57
From: Robert Chung
Subject: Re: wind tunnel
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Bill C wrote:
>> And some make up a number and then argue to the death defending it.
>
> Is that why we don't see more pictures of Bush with his shoes off??
Here he is trying to count to 21:
http://static.crooksandliars.com/2007/03/bush-carrot.jpg
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Date: 31 Mar 2007 09:23:56
From: Kurgan Gringioni
Subject: Re: wind tunnel
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On 30, 10:11 pm, "Robert Chung" <m...@address.invalid > wrote:
> John Forrest Tomlinson wrote:
> >http://www.nyvelocity.com/content.php?id=1300
>
> It's rekably cool what some guys will go through to avoid doing a little
> math.
Fluids calculations that have any resolution whatsoever for a
relatively complicated setup such as a bike/rider is more than a
little math.
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Date: 31 Mar 2007 19:35:00
From: Robert Chung
Subject: Re: wind tunnel
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Kurgan Gringioni wrote:
> On 30, 10:11 pm, "Robert Chung" <m...@address.invalid> wrote:
>> John Forrest Tomlinson wrote:
>>> http://www.nyvelocity.com/content.php?id=1300
>>
>> It's rekably cool what some guys will go through to avoid doing a
>> little math.
>
> Fluids calculations that have any resolution whatsoever for a
> relatively complicated setup such as a bike/rider is more than a
> little math.
Right, but the cross-section of that tunnel is so small that he can't hope
to get an absolute value for CdA; the most he can hope for is an estimate of
relative CdA. In that case, he can get the same level of (im)precision from
an on-bike power meter, which he appears to have.
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Date: 31 Mar 2007 18:32:27
From: Dan Connelly
Subject: Re: wind tunnel
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Robert Chung wrote:
> Right, but the cross-section of that tunnel is so small that he can't hope
> to get an absolute value for CdA; the most he can hope for is an estimate of
> relative CdA. In that case, he can get the same level of (im)precision from
> an on-bike power meter, which he appears to have.
>
>
I think he claims to have precision -- it's accuracy he lacks.
Dan
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Date: 31 Mar 2007 21:08:47
From: Robert Chung
Subject: Re: wind tunnel
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Dan Connelly wrote:
> I think he claims to have precision -- it's accuracy he lacks.
I'd be surprised if he had much precision. Not only is he going to get
turbulence off the walls, but I'm guessing the vanes aren't tuned.
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Date: 31 Mar 2007 20:00:53
From: Dan Connelly
Subject: Re: wind tunnel
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Robert Chung wrote:
> Dan Connelly wrote:
>
>> I think he claims to have precision -- it's accuracy he lacks.
>
> I'd be surprised if he had much precision. Not only is he going to get
> turbulence off the walls, but I'm guessing the vanes aren't tuned.
>
A trivial demonstration is theory says the wind resistance on a 3'3" radius sphere should have around the same drag as a 1'7.5" radius sphere at twice the wind speed.
But I still wonder...
A decent wind resistance test, which I saw first mentioned by Robin Horowitz, should be to run a powertap in conjunction with an iBike. If Crr is right, the single fitting parameter to get agreement is CdA, assuming negligible cross-winds.
Dan
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Date: 31 Mar 2007 22:42:41
From: Robert Chung
Subject: Re: wind tunnel
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Dan Connelly wrote:
> A decent wind resistance test, which I saw first mentioned by Robin
> Horowitz, should be to run a powertap in conjunction with an iBike. If Crr
> is right, the single fitting parameter to get agreement is
> CdA, assuming negligible cross-winds.
I think Coggan talked about doing something like that in the past. IIRC, he
seemed to think the precision was poor.
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Date: 01 Apr 2007 00:17:26
From: Dan Connelly
Subject: Re: wind tunnel
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Robert Chung wrote:
> Dan Connelly wrote:
>
>> A decent wind resistance test, which I saw first mentioned by Robin
>> Horowitz, should be to run a powertap in conjunction with an iBike. If Crr
>> is right, the single fitting parameter to get agreement is
>> CdA, assuming negligible cross-winds.
>
> I think Coggan talked about doing something like that in the past. IIRC, he
> seemed to think the precision was poor.
>
>
Allen & Coggan is pre-IBike, but discusses using power for aerodynamics without a wind gauge: just after dawn, to minimize wind, ride a route in each direction, and do a regression of power/v versus v, with intercept Crr, and slope CdA/2, with power measured with a PowerTap to avoid drivetrain losses.
Dan
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Date: 01 Apr 2007 08:22:59
From: Robert Chung
Subject: Re: wind tunnel
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Dan Connelly wrote:
>> I think Coggan talked about doing something like that in the past.
>> IIRC, he seemed to think the precision was poor.
>
> Allen & Coggan is pre-IBike, but discusses using power for
> aerodynamics without a wind gauge: just after dawn, to minimize wind,
> ride a route in each direction, and do a regression of power/v versus
> v, with intercept Crr, and slope CdA/2, with power measured with a
> PowerTap to avoid drivetrain losses.
Yeah, and I have my doubts about that method. Windless is important, but I
think you'll get poor precision unless you take into account accelerations.
However, I was referring to something else: Andy wrote somewhere or other
that when the iBike came out it reminded him of an experiment he'd done with
an on-bike wind gauge and on-bike power meter sometime before in an attempt
to estimate CdA.
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Date: 31 Mar 2007 08:49:21
From: Fred Fredburger
Subject: Re: wind tunnel
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John Forrest Tomlinson wrote:
> http://www.nyvelocity.com/content.php?id=1300
Where can I order one?
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Date: 31 Mar 2007 08:20:10
From: Bill C
Subject: Re: wind tunnel
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On 31, 2:11 am, "Robert Chung" <m...@address.invalid > wrote:
> John Forrest Tomlinson wrote:
> >http://www.nyvelocity.com/content.php?id=1300
>
> It's rekably cool what some guys will go through to avoid doing a little
> math.
Ya know for some people out here when you run out of fingers and toes
the answer becomes "Many" or "A whole bunch.".
Bill C
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Date: 02 Apr 2007 10:53:06
From: Curtis L. Russell
Subject: Re: wind tunnel
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On 31 2007 08:20:10 -0700, "Bill C" <tritonrider@verizon.net >
wrote:
>Ya know for some people out here when you run out of fingers and toes
>the answer becomes "Many" or "A whole bunch.".
> Bill C
And some make up a number and then argue to the death defending it.
Curtis L. Russell
Odenton, MD (USA)
Just someone on two wheels...
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Date: 02 Apr 2007 19:35:28
From: Howard Kveck
Subject: Re: wind tunnel
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In article <556213d1lfulhr1g7te4iocqohqi8s5got@4ax.com >,
Curtis L. Russell <curtis@md-bicycling.org > wrote:
> On 31 2007 08:20:10 -0700, "Bill C" <tritonrider@verizon.net>
> wrote:
>
> >Ya know for some people out here when you run out of fingers and toes
> >the answer becomes "Many" or "A whole bunch.".
> > Bill C
>
> And some make up a number and then argue to the death defending it.
Could there also be a bit of "accusing everyone else of being stupid / fools /
suckers / Liberals" involved here?
--
tanx,
Howard
Never take a tenant with a monkey.
remove YOUR SHOES to reply, ok?
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Date: 31 Mar 2007 08:11:36
From: Robert Chung
Subject: Re: wind tunnel
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John Forrest Tomlinson wrote:
> http://www.nyvelocity.com/content.php?id=1300
It's rekably cool what some guys will go through to avoid doing a little
math.
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Date: 30 Mar 2007 15:47:09
From: Bill C
Subject: Re: wind tunnel
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On 30, 7:07 pm, John Forrest Tomlinson <usenetrem...@jt10000.com >
wrote:
> http://www.nyvelocity.com/content.php?id=1300
> --
> JT
> ****************************
> Remove "remove" to reply
> Visithttp://www.jt10000.com
> ****************************
That's some really cool stuff. That's gotta be the ultimate cycling
gadget. I love it.
Bill C
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