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Main
Date: 26 Sep 2007 15:56:50
From:
Subject: Details of Howard 1985 Land Speed Record
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The first 212 pages of John Howard's 1993 biography "Pushing the
Limits," written with Peter Nye, are of absolutely no interest to RBT,
being merely a detailed account of an Olympic and international
bicycle champion riding and often winning races of every kind, all
around the world.
We certainly don't care about that sort of thing.
Chapter 14, however, is devoted to Howard's land speed record. The
book is out of print, but you can get a used copy by going to
www.bookfinder.com and putting in his name and the title. Prices
include shipping. My copy arrived in 6 days.
***
"His research quickly showed that he needed a leather suit for
protection in case he fell. Motorcyclists recommended Bates Leathers
in Long Beach, where he was fitted with full-length motorcyclist's
leathers. They were made of red and yellow leather, featuring Lycra
expansion joints to allow movement, and weighed 12 pounds."
--p. 213
[It may be worth explaining to bicyclists that with leathers you tend
to slide on pavement rather than spinning and breaking bones, plus the
suit takes most of the road rash, which is considerably worse at 100+
mph racing speeds. Weight weenies may ponder the fact that the
12-pound suit of leathers, plus the heavy boots, gloves, and helmet,
weigh about as much as the UCI bicycle weight minimum. Some RBT
posters may be pleased to know that "Campagnolo" was emblazoned on
each arm of Howard's leathers.]
***
"It had one brake, a cantilever rear brake taken from a tandem.
Jutting from the front fork was a vertical bar that Howard was to use
to bump against the back of Rick Vesco's race car to slow down below
100 MPH."
--p. 213
[From what I can tell, the brake took care of the rest of the stopping
problem, from 100 MPH downward. you can see the bike and car bumper
bars at http://www.canosoarus.com/08LSRbicycle/LSR%20Bike01.htm ]
***
[The first Bonneville salt flat tests--don't get excited yet.]
"Howard tested the 46-pound prototype on the road to see how it
handled. 'We did some test runs on the Texas World Speedway in College
Station,' he said. 'I pedaled behind a hot-rod Dodge van and we got up
to 75 mph. I felt we had a suitable design.'"
"After returning the bicycle for some adjustments, he did one more
test run. 'The last one was on a highway near Katy, Texas. We cranked
it up to 100 MPH behind the Dodge van.' He laughed at the
recollection. 'We broke 100 MPH on a public highway, like Alfred
Letourner did.'"
--p. 214
[The book mentions on page 5 that Schwinn-sponsored Alfred Letourner
took "three miles to get up to 100 MPH, then he officially clocked
108.92, dashing through the mile in 33.05 seconds. He needed four
miles to slow down." That four-mile slowdown from 109 mph helps to
explain Howard's odd bumper-banging braking tactics.]
"A crucial component in Howard's effort was a special Plexiglass
fairing--a device that fitted over the back of Vesco's low-slung car
and shielded Howard from the wind so he could pedal in the draft. The
fairing was 5 feet tall and 4 1/2 feet wide, and fitted on the back.
Facing Howard on the fairing was a speedometer. He looked through the
fairing with a windshield. In case he needed a reminder, a sign below
the windshield read, 'Faster, you fool.'"
--p. 214
"Because Howard was turning over such a big gear, which carried him
111 feet with every revolution of the pedals, he and his bicycle were
towed by a cable up to 60 MPH. That saved him taking the four miles he
would need under his own power to build to that speed. Vesco
accelerated smoothly. Approachihg 60, Howard disengaged the towline
and started pedaling on his own."
"Howard's bicycle started to wobble. Granules of salt whirled up,
white rain against his visor. Some granules were sucked up uner the
visor and stung his face and eyes. Yet he pedaled carefully in the
protective slipstream, which extended to about seven feet behind the
car, and the bicycle became more stable."
"For three miles, Howard and Vesco accelerated before they started the
timed mile, a section marked for an official 1,760 yards surveyed by
the Bureau of Land Management. Electronic eyes at the beginning and
end of the mile mark the timing trap."
"Howard chased after Vesco's car, careful to stay within the shelter
of the fairing. If he fell behind it, wind would rush at himm with as
much force as smashing into a wall. If he veered outside the breadth
of the slipstream, he would suffer the same smash of air. If he
accelerated too fast, he would hit the bumper bar on the fairing.
His effort required precision handling."
"After they whizzed through the first timed mile, Vesco slowed the
car. Howard decelerated by banging against the bumper bar of Vesco's
car--steel against steel. He had to hit the bar repeatedly rather than
use his hand brake, which would melt from the friction created by
braking at such high speed."
"'It was a tricky process,'" Howard said. 'I slammed into the bumper
bar. I had to be very careful. It was really violent. I put dents in
the back of the bumper bar. Paint cracked and peeled on the bumper and
the bike. But after a while I got used to it.'"
"That afternoon they made five such runs, each as physically demanding
on Howard as a pursuit race. His heart sped up to 195 beats a minute,
and his legs spun like an egg beater."
"'It was a tremendous trhill,' Howard said. 'But it also was
terrifying because we were doing something dangerous. I could feel the
power of the vortex behind me. Let me tell you, that power was
tremendous. The margin for error when riding behind Rick's car was so
small. We had to do everything just right."
"A timer gave Howard a slip of paper stating that he had clocked 114.9
MPH."
p. 215-6
***
[On the next test runs on the San Felipe highway in Baja, Mexico,
considerable problems ensued with head winds, cross-winds, and the
pace car being launched into the air at over 110 mph on the invisible
dips, blasting Howard with paint, dust, and debris as the 2-inch car
clearance suddenly increased. But Howard can be seen raising his speed
to 124.189 MPH in this youtube video:
http://www.youtube.com/watch?v=Py94okBKDU0It
It doesn't show the near-crash where Howard dug a pedal into the
pavement as the pace car bounded into the air off a tiny rise in the
apparently level highway.]
***
[Rain on the Bonneville salt flats and other commitments delayed
things for years.]
"Over the three years that Howard had worked fitfully on the speed
record, he had made minor changes on the bicycle. He covered the
spokes of the rear wheel with Mylar disks, which reduced drag.
Specialized supplied custom tires for his motorcycle wheels, made of
Akront alloy rims. Man and machine were ready."
[This picture may show clear Mylar covering the rear wheel:
http://www.canosoarus.com/08LSRbicycle/LSR%20Bike02.htm
I originally thought that it was the spokes blurring as Howard pedaled
on the test stand, but it could be sun on Mylar, or both at once. In
any case, the picture shows the bump bar nicely. As an aside, there's
nothing special about Akront alloy rims, which were common as dirt in
the motorcycle world by 1974, even on trials machines. They're just
aluminum, strong enough to use, but lighter than steel.]
[The day before the record . . .]
"On Friday, July 19, Howard and Vesco went through six practice runs
to get back in sync as they increased their speed. Each run had Howard
pedaling hard for three miles as they accelerated past mile signposts.
Accelerating strained Howard because the tempo went up constantly.
Then he would pedal furiously through the timed mile, exerting himself
to the limit of his ability. Afterward, he would slam into the back of
Vesco's rear bumper as they slowed."
"At 125 MPH, Howard discovered weird turbulence called Von Karman
Vortex Shedding. 'It kicked me violently forward if I began to fall
back from the pace vehicle's slipstream,' he explained. At that speed,
he was in a narrow bubble of air pressure that was highly sensitive to
any position change. Fortunately, his Mylar covering of the rear wheel
helped the wheel to act as a rudder, and made the bicycle more
stable."
--p. 224
***
[The next day, Howard sets the record . . .]
"But on the fourth run, around noon, Howard was smoothly pedaling past
140 MPH when suddenly he had to fight to control his handlebars. They
jerked in his grip as the rear wheel fishtailed wildly. He was forced
to fall behind the car's slipstream."
"'I felt as though I was being sand-blasted,' he said. 'A wave of air
punched me.' He put his head down and squeezed the handlebars to keep
from being pulled off the bicycle.'"
--p.224-5
[That's how Howard learned that Schrader valves need caps at over 140
MPH. His front tire had a valve cap. The rear didn't. Probably a local
bike shop had stolen it and later sold it at a profit.]
"'That flat only served to boost my confidence,' Howard said."
--p. 225
[It's nice that Howard survived the flat, but his logic suggests that
not all of his screws were properly tightened at the factory.]
***
"At 4:00 p.m., on the sixth run of the day, Howard and Vesco knitted
everything together. Howard worked hard to stay close to the car's
rear bar as they accelerated from 65 MPH to 80 adn then 100. At 110
MPH, he heard the roar of the wind around him, but felt comfortable
with this familiar distraction. Then, past 120 MPH, he hit the Van
Karman effect. He drifted back two feet from the bumper bar, then was
thrown forward hard."
"As he entered the timed mile, his heart was pounding 195 beats a
minute and his legs were spinning at 140 RPM. But now, past the Van
Karman zone, his bicycle felt lighter and shorter."
--p. 225
[Blah, blah, blah, 152.284 MPH, 1985. It sounds as if Howard needed
his pedals and chain.]
Cheers,
Carl Fogel
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Date: 27 Sep 2007 16:27:17
From:
Subject: Re: Details of Howard 1985 Land Speed Record
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On Wed, 26 Sep 2007 15:56:50 -0600, carlfogel@comcast.net wrote:
[snip]
>"Over the three years that Howard had worked fitfully on the speed
>record, he had made minor changes on the bicycle. He covered the
>spokes of the rear wheel with Mylar disks, which reduced drag.
>Specialized supplied custom tires for his motorcycle wheels, made of
>Akront alloy rims. Man and machine were ready."
>
>[This picture may show clear Mylar covering the rear wheel:
>
> http://www.canosoarus.com/08LSRbicycle/LSR%20Bike02.htm
>
>I originally thought that it was the spokes blurring as Howard pedaled
>on the test stand, but it could be sun on Mylar, or both at once.
[snip]
Nope, the closer I look, the more that test-stand picture looks like a
no-Mylar-cover rear wheel:
http://www.canosoarus.com/08LSRbicycle/LSR%20Bike02.htm
You can see the shadow of the rear tire on the ground through the
probably whirling spokes.
This salt-flats picture shows that the rear Mylar cover reflected
things like a convex mirror when photographed from a slight angle:
http://www.canosoarus.com/08LSRbicycle/LSR%20Bike01.htm
Here's the same picture, enlarged from the better-resolution version
on the book cover:
http://i24.tinypic.com/10ztiu0.jpg
In the enlargement, the reflection on the rear Mylar-covered-wheel
shows a white cloud in the blue Utah sky, with the horizon slightly
tilted.
Notice the black line trailing from the heavy flange behind the
headset, extending back toward Howard's yellow right knee?
It's a doohickey, not a shadow on the ground.
The doohickey is also visible in the test-stand picture, where again
it's clearly not a shadow on the ground and extends back toward
Howard's red left leg:
http://www.canosoarus.com/08LSRbicycle/LSR%20Bike02.htm
I wonder if the doohickey is the antenna for the radio-control for the
pace-car throttle, which may be housed in the flanged area behind the
headset. The radio-control is mentioned elsewhere, but not in the
book.
The big dingus below the window in the pace screen may be a camera or
the speedometer mentioned in the book.
The curious round hole in the lower back of the shield is not a
shadow. It may serve some aerodynamic purpose.
Cheers,
Carl Fogel
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Date: 27 Sep 2007 23:51:27
From:
Subject: Re: Details of Howard 1985 Land Speed Record
|
On Thu, 27 Sep 2007 16:27:17 -0600, carlfogel@comcast.net wrote:
>On Wed, 26 Sep 2007 15:56:50 -0600, carlfogel@comcast.net wrote:
>
>[snip]
>
>>"Over the three years that Howard had worked fitfully on the speed
>>record, he had made minor changes on the bicycle. He covered the
>>spokes of the rear wheel with Mylar disks, which reduced drag.
>>Specialized supplied custom tires for his motorcycle wheels, made of
>>Akront alloy rims. Man and machine were ready."
>>
>>[This picture may show clear Mylar covering the rear wheel:
>>
>> http://www.canosoarus.com/08LSRbicycle/LSR%20Bike02.htm
>>
>>I originally thought that it was the spokes blurring as Howard pedaled
>>on the test stand, but it could be sun on Mylar, or both at once.
>
>[snip]
>
>Nope, the closer I look, the more that test-stand picture looks like a
>no-Mylar-cover rear wheel:
>
> http://www.canosoarus.com/08LSRbicycle/LSR%20Bike02.htm
>
>You can see the shadow of the rear tire on the ground through the
>probably whirling spokes.
>
>This salt-flats picture shows that the rear Mylar cover reflected
>things like a convex mirror when photographed from a slight angle:
>
> http://www.canosoarus.com/08LSRbicycle/LSR%20Bike01.htm
>
>Here's the same picture, enlarged from the better-resolution version
>on the book cover:
>
> http://i24.tinypic.com/10ztiu0.jpg
>
>In the enlargement, the reflection on the rear Mylar-covered-wheel
>shows a white cloud in the blue Utah sky, with the horizon slightly
>tilted.
>
>Notice the black line trailing from the heavy flange behind the
>headset, extending back toward Howard's yellow right knee?
>
>It's a doohickey, not a shadow on the ground.
>
>The doohickey is also visible in the test-stand picture, where again
>it's clearly not a shadow on the ground and extends back toward
>Howard's red left leg:
>
> http://www.canosoarus.com/08LSRbicycle/LSR%20Bike02.htm
>
>I wonder if the doohickey is the antenna for the radio-control for the
>pace-car throttle, which may be housed in the flanged area behind the
>headset. The radio-control is mentioned elsewhere, but not in the
>book.
>
>The big dingus below the window in the pace screen may be a camera or
>the speedometer mentioned in the book.
>
>The curious round hole in the lower back of the shield is not a
>shadow. It may serve some aerodynamic purpose.
>
>Cheers,
>
>Carl Fogel
A black and white picture of John Howard on the test stand, showing
the black doohickey trailing from the headset flange:
http://www.bikecult.com/works/chainring/jhoward.jpg
Cheers,
Carl Fogel
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Date: 27 Sep 2007 19:04:06
From: joseph.santaniello@gmail.com
Subject: Re: Details of Howard 1985 Land Speed Record
|
On Sep 27, 7:36 pm, Ben C <spams...@spam.eggs > wrote:
> On 2007-09-27, joseph.santanie...@gmail.com <joseph.santanie...@gmail.com> wrote:
>
>
>
> > On Sep 27, 6:13 pm, Ben C <spams...@spam.eggs> wrote:
> >> On 2007-09-27, Tim McNamara <tim...@bitstream.net> wrote:
>
> >> > In article <mbjlf39qslt0bu7o63i97jt5tcd3lfr...@4ax.com>,
> >> > carlfo...@comcast.net wrote:
>
> >> >> "At 125 MPH, Howard discovered weird turbulence called Von Karman
> >> >> Vortex Shedding. 'It kicked me violently forward if I began to fall
> >> >> back from the pace vehicle's slipstream,' he explained.
>
> >> > Isn't that what Jobst was writing about in the other thread?
>
> >> I think Jobst was proposing that the riders actually use the force from
> >> the turbulent air behind to propel the bicycle along and that they
> >> therefore don't need cranks except for show.
>
> >> It seems clear now that he was mistaken about that.
>
> >> In any case he seemed to be basing his view mostly only on the very
> >> questionable assumption that it is not humanly possible to overcome RR
> >> and spoke windage at 166mph.
>
> > What other thread is this? Sounds interesting.
>
> I think it was mostly in this one (subject "Speed Record")
>
> http://groups.google.co.uk/group/rec.bicycles.tech/browse_thread/thre...
>
> orhttp://tinyurl.com/yr7qr9
>
> Actually that seems to be "A new use for Spokes". I think the subject
> changed during the thread. Around the 25th post it changed to land speed
> record attempts.
>
> Watch out for my bad math: I said in earlier posts that it needed 1300W
> to ride at 166mph with no wind resistance. That was based on my
> confusing the units. The correct estimate was < 400W as Ron Ruff pointed
> out.
That was a good read!
A few days ago I had a brilliant motor-pacing ride. A road I ride
regularly has a slight rise over a blind curve into a semi-steep
downhill that has a reduced 50kmh speed limit. This means that cars
behind me on the rise have to wait until we get to the downhill to
pass me. They do so invariably because they have just sat behind me at
30kmh or so for a few seconds, they can't imagine that within a few
seconds I will be exceeding the posted speed limit. So they end up
passing me at 70kmh or so. This time I was passed by a big flat-bed
truck with some lumber piled up on the rear of the bed. Trucks are
prefect to anonymously motor-pace because they do not accelerate hard,
and their drivers are allergic to jumping on the brakes. So this truck
rolled by giving me the perfect oppurtunity for almost 10km of monster
speed. I ended up getting dropped on a hill, still spinning my 53x12.
It was pouring rain and behind this truck is was an absolute
maelstrom! I couldn't see the road, I just kept myself centered
between the lights at about 2m distance. Not exactly that nutter
almost kissing the railroad ties, but more than exciting enough.
Unfortunately I wasn't going fast enough to just be able to
coast... ;-)
Joseph
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Date: 27 Sep 2007 16:49:46
From: joseph.santaniello@gmail.com
Subject: Re: Details of Howard 1985 Land Speed Record
|
On Sep 27, 6:13 pm, Ben C <spams...@spam.eggs > wrote:
> On 2007-09-27, Tim McNamara <tim...@bitstream.net> wrote:
>
> > In article <mbjlf39qslt0bu7o63i97jt5tcd3lfr...@4ax.com>,
> > carlfo...@comcast.net wrote:
>
> >> "At 125 MPH, Howard discovered weird turbulence called Von Karman
> >> Vortex Shedding. 'It kicked me violently forward if I began to fall
> >> back from the pace vehicle's slipstream,' he explained.
>
> > Isn't that what Jobst was writing about in the other thread?
>
> I think Jobst was proposing that the riders actually use the force from
> the turbulent air behind to propel the bicycle along and that they
> therefore don't need cranks except for show.
>
> It seems clear now that he was mistaken about that.
>
> In any case he seemed to be basing his view mostly only on the very
> questionable assumption that it is not humanly possible to overcome RR
> and spoke windage at 166mph.
What other thread is this? Sounds interesting.
Joseph
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Date: 27 Sep 2007 12:36:28
From: Ben C
Subject: Re: Details of Howard 1985 Land Speed Record
|
On 2007-09-27, joseph.santaniello@gmail.com <joseph.santaniello@gmail.com > wrote:
> On Sep 27, 6:13 pm, Ben C <spams...@spam.eggs> wrote:
>> On 2007-09-27, Tim McNamara <tim...@bitstream.net> wrote:
>>
>> > In article <mbjlf39qslt0bu7o63i97jt5tcd3lfr...@4ax.com>,
>> > carlfo...@comcast.net wrote:
>>
>> >> "At 125 MPH, Howard discovered weird turbulence called Von Karman
>> >> Vortex Shedding. 'It kicked me violently forward if I began to fall
>> >> back from the pace vehicle's slipstream,' he explained.
>>
>> > Isn't that what Jobst was writing about in the other thread?
>>
>> I think Jobst was proposing that the riders actually use the force from
>> the turbulent air behind to propel the bicycle along and that they
>> therefore don't need cranks except for show.
>>
>> It seems clear now that he was mistaken about that.
>>
>> In any case he seemed to be basing his view mostly only on the very
>> questionable assumption that it is not humanly possible to overcome RR
>> and spoke windage at 166mph.
>
> What other thread is this? Sounds interesting.
I think it was mostly in this one (subject "Speed Record")
http://groups.google.co.uk/group/rec.bicycles.tech/browse_thread/thread/26a92b800c862143/b8d318b2690c92ef?hl=en&#
or http://tinyurl.com/yr7qr9
Actually that seems to be "A new use for Spokes". I think the subject
changed during the thread. Around the 25th post it changed to land speed
record attempts.
Watch out for my bad math: I said in earlier posts that it needed 1300W
to ride at 166mph with no wind resistance. That was based on my
confusing the units. The correct estimate was < 400W as Ron Ruff pointed
out.
|
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Date: 27 Sep 2007 10:09:52
From: Ben C
Subject: Re: Details of Howard 1985 Land Speed Record
|
On 2007-09-26, carlfogel@comcast.net <carlfogel@comcast.net > wrote:
[...]
> "Howard chased after Vesco's car, careful to stay within the shelter
> of the fairing. If he fell behind it, wind would rush at himm with as
> much force as smashing into a wall.
[...]
> "At 125 MPH, Howard discovered weird turbulence called Von Karman
> Vortex Shedding. 'It kicked me violently forward if I began to fall
> back from the pace vehicle's slipstream,' he explained. At that speed,
> he was in a narrow bubble of air pressure that was highly sensitive to
> any position change.
[...]
> [Blah, blah, blah, 152.284 MPH, 1985. It sounds as if Howard needed
> his pedals and chain.]
All most interesting.
It looks like Ron Ruff's educated guess was spot on-- he had to pedal in
the "bubble" where he _wasn't_ being pushed by the vortex.
The force from the vortex behind sounds like it's more than big enough
to propel a rider at 166mph in theory (which is sort of what we thought)
but far too turbulent.
|
| | |
Date: 27 Sep 2007 13:37:46
From:
Subject: Re: Details of Howard 1985 Land Speed Record
|
On Thu, 27 Sep 2007 10:09:52 -0500, Ben C <spamspam@spam.eggs > wrote:
>On 2007-09-26, carlfogel@comcast.net <carlfogel@comcast.net> wrote:
>[...]
>> "Howard chased after Vesco's car, careful to stay within the shelter
>> of the fairing. If he fell behind it, wind would rush at himm with as
>> much force as smashing into a wall.
>[...]
>> "At 125 MPH, Howard discovered weird turbulence called Von Karman
>> Vortex Shedding. 'It kicked me violently forward if I began to fall
>> back from the pace vehicle's slipstream,' he explained. At that speed,
>> he was in a narrow bubble of air pressure that was highly sensitive to
>> any position change.
>[...]
>> [Blah, blah, blah, 152.284 MPH, 1985. It sounds as if Howard needed
>> his pedals and chain.]
>
>All most interesting.
>
>It looks like Ron Ruff's educated guess was spot on-- he had to pedal in
>the "bubble" where he _wasn't_ being pushed by the vortex.
>
>The force from the vortex behind sounds like it's more than big enough
>to propel a rider at 166mph in theory (which is sort of what we thought)
>but far too turbulent.
Dear Ben,
Yes, that was what I kept wondering.
Posters seemed to be assuming some sort of unknown vortices that
somehow provided a steady pressure that would push a bicyclist forward
like a pleasant wind.
But the only vortices that I knew of that would apply were Von Karman
vortices, which are violently alternating mini-hurricane eddies.
So I had to find an account from one of the two men who have actually
been on a bicycle at 150+ mph to see what a rider noticed.
Von Karman vortices are by their very nature violent alternating kicks
from swirling eddies from each side, with as much sideways as forward
component. The wiki page gives a fair idea of the side-to-side and
intermittent nature of the slaps that you'd get if you slipped back
into the VK area behind the ordinary draft zone:
http://en.wikipedia.org/wiki/Von_K%C3%A1rm%C3%A1n_vortex_street
For Howard's particular setup, the VK vortices were noticeable only
between 125 and 140 mph--his first test runs involved pedalling up
from 60 mph after he dropped the tow to 110 mph, so there was no
problem.
Only at 125 mph did he notice the violent kicking if he slipped too
far back from the pace car, where the VK vortices were swirling. To
avoid disaster, he pedalled back into the "quiet" draft zone ahead of
the vortices--a howling mess, but quite placid compared to the
nightmare where the VK vortices were eddying.
At 140 mph, things smoothed out, either because the VK eddies vanished
or because they formed too far back for Howard to notice, and he
pedalled on up to 150 mph.
Cheers,
Carl Fogel
|
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Date: 27 Sep 2007 09:51:31
From: Tim McNamara
Subject: Re: Details of Howard 1985 Land Speed Record
|
In article <mbjlf39qslt0bu7o63i97jt5tcd3lfr0em@4ax.com >,
carlfogel@comcast.net wrote:
> "At 125 MPH, Howard discovered weird turbulence called Von Karman
> Vortex Shedding. 'It kicked me violently forward if I began to fall
> back from the pace vehicle's slipstream,' he explained.
Isn't that what Jobst was writing about in the other thread?
|
| | |
Date: 27 Sep 2007 13:25:05
From:
Subject: Re: Details of Howard 1985 Land Speed Record
|
On Thu, 27 Sep 2007 09:51:31 -0500, Tim McNamara
<timmcn@bitstream.net > wrote:
>In article <mbjlf39qslt0bu7o63i97jt5tcd3lfr0em@4ax.com>,
> carlfogel@comcast.net wrote:
>
>> "At 125 MPH, Howard discovered weird turbulence called Von Karman
>> Vortex Shedding. 'It kicked me violently forward if I began to fall
>> back from the pace vehicle's slipstream,' he explained.
>
>Isn't that what Jobst was writing about in the other thread?
Dear Tim,
The account shows what's wrong with Jobst's theory that land speed
riders can just be towed up to speed while riding chainless bicycles
and then coast happily behind the pacer while being blown forward by
the draft.
First, the tow was dropped at about 60 mph and Howard then pedalled on
up 90 more mph to 150+ mph. He wasn't towed up to 150 mph.
Howard noticed no Von Karman vortex effect below 125 mph, and the
effect vanished at about 140 mph. They seem to have appeared abruptly
at 125 mph. The sudden appearance as speed increases is typical.
The Von Karman vortices may have existed over a wider range of speeds
than Howard noticed, but they were so far back or so weak that he
didn't notice them. Like many aerodynamic effects, they appear in
certain speed ranges, according to the shape of the airfoil and the
nature of the fluid.
But the violent "kicking" effect was noticeable only between 125 and
140 mph, leaving Howard to provide the power from 60 to 125 mph and
the crucial 140 to 152 mph ranges.
And the vortices were no help in their apparent 125 to 140 mph range.
Howard found that he had to keep pedalling to stay in the ordinary
draft _ahead_ of the vortices because the VK vortices provide only
violent kicks or slaps from alternate sides, with as much sideways
motion as forward motion.
Drop back into the VK turbulence, and you're leaving the low-pressure
draft familiar to the peloton and entering the area analogous to where
a flag begins to ripple violently from side to side.
The wiki page gives a well-known animation of VK turbulence:
http://en.wikipedia.org/wiki/Von_K%C3%A1rm%C3%A1n_vortex_street
Drop back into the VK zone, and the swirling from each side will beat
you to death, if you don't fall over sideways first. For the speeds,
fluid, and airfoil involved, the danger zone is awfully close to the
back of the pace car, but the ordinary drafting zone still exists.
Cheers,
Carl Fogel
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Date: 27 Sep 2007 11:13:37
From: Ben C
Subject: Re: Details of Howard 1985 Land Speed Record
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On 2007-09-27, Tim McNamara <timmcn@bitstream.net > wrote:
> In article <mbjlf39qslt0bu7o63i97jt5tcd3lfr0em@4ax.com>,
> carlfogel@comcast.net wrote:
>
>> "At 125 MPH, Howard discovered weird turbulence called Von Karman
>> Vortex Shedding. 'It kicked me violently forward if I began to fall
>> back from the pace vehicle's slipstream,' he explained.
>
> Isn't that what Jobst was writing about in the other thread?
I think Jobst was proposing that the riders actually use the force from
the turbulent air behind to propel the bicycle along and that they
therefore don't need cranks except for show.
It seems clear now that he was mistaken about that.
In any case he seemed to be basing his view mostly only on the very
questionable assumption that it is not humanly possible to overcome RR
and spoke windage at 166mph.
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Date: 27 Sep 2007 10:04:20
From: joseph.santaniello@gmail.com
Subject: Re: Details of Howard 1985 Land Speed Record
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On Sep 26, 11:56 pm, carlfo...@comcast.net wrote:
> [It's nice that Howard survived the flat, but his logic suggests that
> not all of his screws were properly tightened at the factory.]
And the rest of this narrative would suggest otherwise?
Joseph
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Date: 26 Sep 2007 17:53:10
From: futrino
Subject: Re: Details of Howard 1985 Land Speed Record
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carlfogel@comcast.net wrote:
> The first 212 pages of John Howard's 1993 biography "Pushing the
> Limits," written with Peter Nye, are of absolutely no interest to RBT,
> being merely a detailed account of an Olympic and international
> bicycle champion riding and often winning races of every kind, all
> around the world.
>
> We certainly don't care about that sort of thing.
>
> Chapter 14, however, is devoted to Howard's land speed record. The
> book is out of print, but you can get a used copy by going to
> www.bookfinder.com and putting in his name and the title. Prices
> include shipping. My copy arrived in 6 days.
>
etc
http://www.youtube.com/watch?v=Py94okBKDU0
corrected youtube url
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