wind tunnel

[Bill C]

On Mar 30, 7:07 pm, John Forrest Tomlinson >
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

[John Forrest Tomlinson]

http://www.nyvelocity.com/content.php?id=1300
--
JT
****************************
Remove "remove" to reply
Visit http://www.jt10000.com
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[Robert Chung]

John Forrest Tomlinson wrote:
> http://www.nyvelocity.com/content.php?id=1300

It's remarkably cool what some guys will go through to avoid doing a little
math.

[Bill C]

On Mar 31, 2:11 am, "Robert Chung" > wrote:
> John Forrest Tomlinson wrote:
> >http://www.nyvelocity.com/content.php?id=1300
>
> It's remarkably 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

[Fred Fredburger]

John Forrest Tomlinson wrote:
> http://www.nyvelocity.com/content.php?id=1300

Where can I order one?

[Kurgan Gringioni]

On Mar 30, 10:11 pm, "Robert Chung" > wrote:
> John Forrest Tomlinson wrote:
> >http://www.nyvelocity.com/content.php?id=1300
>
> It's remarkably 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.

[Robert Chung]

Kurgan Gringioni wrote:
> On Mar 30, 10:11 pm, "Robert Chung" > wrote:
>> John Forrest Tomlinson wrote:
>>> http://www.nyvelocity.com/content.php?id=1300
>>
>> It's remarkably 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.

[Dan Connelly]

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

[Robert Chung]

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.

[Dan Connelly]

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

[Robert Chung]

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.

[Dan Connelly]

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

[Robert Chung]

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.

[Curtis L. Russell]

On 31 Mar 2007 08:20:10 -0700, "Bill C" >
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...

[Bill C]

On Apr 2, 10:53 am, Curtis L. Russell > wrote:
> On 31 Mar 2007 08:20:10 -0700, "Bill C" >
> 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

[Robert Chung]

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

[Andy Coggan]

On Apr 1, 1:22 am, "Robert Chung" > 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

[Howard Kveck]

In article >,
Curtis L. Russell > wrote:

> On 31 Mar 2007 08:20:10 -0700, "Bill C" >
> 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?

[Qui si parla Campagnolo]

On Mar 31, 9:20 am, "Bill C" > wrote:
> On Mar 31, 2:11 am, "Robert Chung" > wrote:
>
> > John Forrest Tomlinson wrote:
> > >http://www.nyvelocity.com/content.php?id=1300
>
> > It's remarkably 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.....

[Kevin Tuttle]

On Mar 31, 11:49 am, Fred Fredburger
> 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.