ULTRA marathon cycling
Douglas Reece
An article in the Arizona Republic recently tells of Michael Secrest's hope to
ride from Los Angeles to Jacksonville, FL in 48 hours. Apparently he
rode 1216 miles in 24 hours in April 1990. This was at Phoenix International
Raceway, riding behind a diesel truck with big plastic shields to deflect air.
Since he has done RAAM successfully before, he figures he could keep up
that pace for two days. The truck would carry 500 gallons of fuel and three
drivers for the cross country trip so it wouldn't have to stop.
All he needs now is cooperation from the state governments along the route,
and money.
Doug
B.J.
>
>An article in the Arizona Republic recently tells of Michael Secrest's hope to
>ride from Los Angeles to Jacksonville, FL in 48 hours. Apparently he
>rode 1216 miles in 24 hours in April 1990. This was at Phoenix International
Wait a sec! According to my trusty calculator, the guy averaged 50.7 mph
non-stop for 24 hours!!! Must have been Superman's brother. I have a hard
time *driving* that far in 24 hours. Something is not right here.
**bj**
Donald A. Varvel
Read carefully the part you deleted.
He was drafting a carefully-constructed truck. At best his
pedalling was overcoming rolling resistance. It was also on
a track, so he didn't have to worry about potholes.
This sort of thing makes a great stunt. Staying upright on a
bicycle for 48 hours is far from trivial. Avoiding potholes
has to be a major concern. Getting up to speed in the first
place is difficult. Coordinating the speed of the truck with
the speed of the rider can be tricky. Emergency stops would
be problematical. That is, I'm not suggesting the whole thing
would be easy.
I *am* suggesting that this sort of thing is not comparable
to a bicycle race or speed record attempt.
-- Don Varvel (var...@cs.utexas.edu)
George Dibos
Your last word is the key--Michael (indeed, all RAAM types) have had to
operate on a shoestring since it all began. I used to live about four
blocks from Mike, and know how he was forced to live to be able to cycle
full time. Writers and painters call it "starving for their art". When
you want to be the greatest ultra-marathon cyclist in the world, it's
just plain starving...
And speaking of RAAM, it starts TOMORROW, you know! Stay tuned--one of my
best friends is in it--Matt Bond--and I'll post the race's progress every
chance I get.
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Steven W Bixby
> to
>>ride from Los Angeles to Jacksonville, FL in 48 hours. Apparently he
>>rode 1216 miles in 24 hours in April 1990. This was at Phoenix
> International
>Wait a sec! According to my trusty calculator, the guy averaged 50.7 mph
>non-stop for 24 hours!!! Must have been Superman's brother. I have a hard
>time *driving* that far in 24 hours. Something is not right here.
I bet I could too, (for a few seconds, anyway) if I was mashing a huge
chainring and drafting an 18 wheeler...... Seems like he could all but sit
back and watch the scenery go by without pedalling....!
-swb-
Dennis Allard
> I bet I could too, (for a few seconds, anyway) if I was mashing a huge
> chainring and drafting an 18 wheeler...... Seems like he could all but sit
> back and watch the scenery go by without pedalling....!
If you think you can beat Secrest, either paced or unpaced for anywhere from
two to eight days, then why don't you give it a try. He currently holds
the unpaced cross continental record of under eight days. (unpaced)
Dennis Allard
all...@isi.edu
George Dibos
I heatily agree, Mr. Bixby... Mike has always been most eager for people
to shoot for his records. By all means, sit back and watch the scenery
go by. You might first check yourself to see how long it takes you to
ride 500 miles, though--if you have the legs and heart to do it in under
24 hours, maybe you have what it takes to go after a couple of them. After
that one's notched, give his transcontinental (unpaced, solo, supported)
record a go: 7 days, 23 hours, 45 minutes. Lots of scenery there!
Steven W Bixby
Oh, don't worry, I wouldn't have a chance in hell of riding anything near like
Secrest, no worry at all.
But what kind of a record is he setting when he rides behind a specially
designed and implemented drafting vehicle? An 18 wheeler, no less? As at
least one other person suggested, motorpacing, as he did, is a sham. I would
think that just about any half-serious rider would be able to get up to a
consistent 50+ mph speed when using a big chainring and a cyclist-sucking
vehicle to propel him/her to high speed with minimum drag. Then the feat
becomes more aerobic exercise than it does high-speed cycling.
Although most of what I know of Secrest I learned through the net, I have a
great deal of respect for what he does. I just think using a big truck as
a specially implemented drafting vehicle makes his latest feat less meaningful.
Finally, my first response was that of jest - I didn't and don't like to flame
people - it's pointless.
-swb- (sbi...@cup.portal.com)
Dennis Allard
Bixby) writes:
> Dennis Allard (and others) take offense at a comment I made....
> >sbi...@cup.portal.com (Steven W Bixby) writes:
> >> chainring and drafting an 18 wheeler...... Seems like he could all
but sit
> >> back and watch the scenery go by without pedalling....!
> >
> >two to eight days, then why don't you give it a try. He currently holds
> >the unpaced cross continental record of under eight days. (unpaced)
>
> Oh, don't worry, I wouldn't have a chance in hell of riding anything
near like
> Secrest, no worry at all.
>
> But what kind of a record is he setting when he rides behind a specially
> designed and implemented drafting vehicle? An 18 wheeler, no less? As at
> least one other person suggested, motorpacing, as he did, is a sham. I would
> think that just about any half-serious rider would be able to get up to a
> consistent 50+ mph speed when using a big chainring and a cyclist-sucking
> vehicle to propel him/her to high speed with minimum drag. Then the feat
> becomes more aerobic exercise than it does high-speed cycling.
>
> Although most of what I know of Secrest I learned through the net, I have a
> great deal of respect for what he does. I just think using a big truck as
> a specially implemented drafting vehicle makes his latest feat less
meaningful.
>
> Finally, my first response was that of jest - I didn't and don't like
to flame
> people - it's pointless.
>
> -swb- (sbi...@cup.portal.com)
Sorry if my retort seemed a flame. Anyway, you and Jobst have me convinced,
pacing behind an 18 wheeler demonstrates nothing.
Dennis
Thomas H. Kunich
you of that BS about the bike being drawn along by the
'wind' from the 18 wheeler? :-)
Don't believe it. As long ago as Mile-a-minute Murphy
that sort of pseudo-scientific garbage has been passed around.
It was proven then and many times since that at the speeds
used for these bicycle records that nothing of the sort exists.
The vehicle has a dead spot behind it where the air is moving at about
the speed of the vehicle. The rider _only_ (ONLY?) has to
overcome the rolling resistance, which is still pretty large.
More problems occur in a long distance challenge since I for
one wouldn't like riding behind something that blocked off view
of 50 mph pot-holes. :-)
Dennis Allard
> You mean to tell me that these guys actaully convinced
> you of that BS about the bike being drawn along by the
> 'wind' from the 18 wheeler? :-)
>
> Don't believe it. As long ago as Mile-a-minute Murphy
> that sort of pseudo-scientific garbage has been passed around.
> It was proven then and many times since that at the speeds
> used for these bicycle records that nothing of the sort exists.
What I believe is that Secrest will be drafting a vehicle which only
elimiates air drag, but does not create the wind effect. I think
his main problem will be local police.
Another related topic is the Bordeaux-Paris classic where cyclists
are paced by motorcycles for the first couple of hundred miles and then
ride the remaining coupld of hundred solo. I think it is no longer being
run, but I'll do some research and post details unless some other
volunteer beats me to it (all volunteers accepted).
Dennis Allard
all...@isi.edu
George Dibos
Well, the guy passing around most of the pseudo-scientific garbage has
a European sounding name, and everyone knows the Euros know more about
things cycling than we United Statesians... so I guess he won the
debate by virtue of FIF (foreign intimidation factor).
You are right, of course: resistance is resistance, no matter what the
source; and removing (most) of the air resistance simply moves rolling
resistance and other mechanical stuff to the head of the line. WHICH
STILL HAS TO BE OVERCOME BY THE RIDER. As I've said in this group
before, I have had significant contact with some of these RAAM guys,
Secrest included, and have SEEN and TRIED what they do... And they
are astonishing athletes. Period. And I am also sick of the Euros
scoffing at their achievements, calling them "neanderthals" and the
like. It's simply arrogance rationalizing ignorance.
Harry Phinney
: You are right, of course: resistance is resistance, no matter what the
: source; and removing (most) of the air resistance simply moves rolling
: resistance and other mechanical stuff to the head of the line. WHICH
: STILL HAS TO BE OVERCOME BY THE RIDER.
This is not correct. A properly designed fairing on the lead vehicle
can and most certainly does provide a propelling wind for the following
cyclist. As Jobst offered in example, have you ever ridden in a
convertible car and felt the wind blowing your hair forward? This is a
common trait of most convertibles, and amply demonstrates this sort of
propulsion. Even if you assume that Secrest is much more powerful that
Eddy Merckx and Francesco Moser combined, the power he produces is
absolutely negligible compared to the power required to propel a bicycle
and rider at those speeds. The power comes from the lead vehicle, not
from the rider. If the rider were truly forced to overcome rolling
resistance, then a rider going three times Secrest's speed would have to
produce three times the power. Do you really believe that John Howard
cranks out around three times the horsepower of Secrest? Actually,
since Howard did his ride on the salt flats with motorcycle tires his
coefficient of rolling resistance was much higher than Secrest's, so he
must have put out well over three times the power of Secrest. No, I
don't think so.
: As I've said in this group
: before, I have had significant contact with some of these RAAM guys,
: Secrest included, and have SEEN and TRIED what they do... And they
: are astonishing athletes. Period. And I am also sick of the Euros
: scoffing at their achievements, calling them "neanderthals" and the
: like. It's simply arrogance rationalizing ignorance.
Nobody in this discussion has made any disparaging remarks about the
abilities of Secrest or other RAAM participants. What has been stated
is that motor paced records in general are tricky, dangerous stunts
which do not necessarily require great riding strength. I will
certainly admit that I could not equal Secrest's 24 hour motor paced
record, but in this case it is an indication of his ability to operate
better under conditions of sleep deprivation, not his cycling ability.
This is not meant to denigrate his abilities, but rather to point out
that this particular record indicates nothing about his cycling
abilities.
Harry Phinney ha...@hp-pcd.cv.hp.com
Donald A. Varvel
>In article <28nmz#f.t...@netcom.com>, to...@netcom.com (Thomas H. Kunich) writes:
>|> You mean to tell me that these guys actaully convinced
>|> you of that BS about the bike being drawn along by the
>|> 'wind' from the 18 wheeler? :-)
>|> Don't believe it. As long ago as Mile-a-minute Murphy
>|> that sort of pseudo-scientific garbage has been passed around.
>|> It was proven then and many times since that at the speeds
>|> used for these bicycle records that nothing of the sort exists.
that nobody followed up on, but this is getting entirely out of hand.
Note the use of the term "BS". To back up the statement that what
somebody else said is "BS", we have "It was proven then and many
times since ..." The use of the passive voice allows one to omit
mentioning *who* did the action referred to.
I have ridden in a convertible at highway speeds, which are what
we are talking about here, and have *felt* what little hair I have
being blown forward. Thus, I know from my own experience that the
effect referred to *does* exist. I am at least very skeptical of
claims of proof of the nonexistance of a phenomenon I have
experienced.
>|> The vehicle has a dead spot behind it where the air is moving at about
>|> the speed of the vehicle. The rider _only_ (ONLY?) has to
>|> overcome the rolling resistance, which is still pretty large.
>|> More problems occur in a long distance challenge since I for
>|> one wouldn't like riding behind something that blocked off view
>|> of 50 mph pot-holes. :-)
No, the vehicle has an area behind it with a variety of airflows,
depending on location and precise speed and several other factors.
In some places the air swirls forward faster than the vehicle. As
I mentioned in my earlier posting, it is not trivial to stay upright
on a bicycle for 48 hours and road irregularities such as potholes
would indeed be a major problem. That leaves us with an activity
comparable to auto racing. It does *not* leave us with anything
comparable to bicycle racing.
>Well, the guy passing around most of the pseudo-scientific garbage has
>a European sounding name, and everyone knows the Euros know more about
>things cycling than we United Statesians... so I guess he won the
>debate by virtue of FIF (foreign intimidation factor).
I may be a little more difficult to dismiss by means of simple
bigotry. I'm as Middle American as they come.
>You are right, of course: resistance is resistance, no matter what the
>source; and removing (most) of the air resistance simply moves rolling
>resistance and other mechanical stuff to the head of the line. WHICH
>STILL HAS TO BE OVERCOME BY THE RIDER.
If people don't believe you when you shout, try saying it three times.
>As I've said in this group
>before, I have had significant contact with some of these RAAM guys,
>Secrest included, and have SEEN and TRIED what they do... And they
>are astonishing athletes. Period.
No argument here. I'm just curious why one of these fine athletes
feels the need to engage in a blatant and essentially meaningless
publicity stunt. I can imagine several very good answers, mostly
having to do with money. If it brings publicity and sponsorship into
ultra-marathon cycling, fine.
>And I am also sick of the Euros
>scoffing at their achievements, calling them "neanderthals" and the
>like. It's simply arrogance rationalizing ignorance.
Where's the quantifier? "Some" or "All"? When the quantifier is
omitted one should generally assume universal. *All* "Euros" (I
presume "Europeans") do these things? Jobst's position on motor-
pacing is well-known and IMHO correct, but I don't remember his
ever denigrating the real athletic achievements of ultra-marathoners.
A few years ago a European racer was quoted as saying that anyone
in the TdF pack could win the RAAM. Newspapers tend to pick up
that sort of thing, but I doubt that many people take it seriously.
Is there an area of contention here that I'm not aware of?
-- Don Varvel (var...@cs.utexas.edu)
Eric House
>
>What I believe is that Secrest will be drafting a vehicle which only
>elimiates air drag, but does not create the wind effect. I think
>his main problem will be local police.
>
Why on earth would he design a fairing that "only eliminates wind drag" (if
such a thing were possible -- you'd have to know *exaclty* how far the
bike would be from the fairing and then keep it there at all times) when
something that would be even better were possible?
We are talking, after all, about a guy who not only holds the record for
the transcontinental ride but also spends record amounts each time he
does RAAM -- upwards of $35,000 when others are doing well on a tenth of
that. Motor homes, multiple spy vehicles, huge crews -- the guy seems to
believe that you train hard and they buy whatever additional advantages
you can.
Not that there's anything wrong with that per se -- it's part of the game
as it's played -- but it makes it seem unlikely to me that he'd forgo any
obvious advantage in the interest of making things more "fair" in some
undefinable sense.
(And I really hope I've got the right guy here....)
--
****************************************************************************
Eric House "My employer doesn't share its opinions with
me, so I can share only mine with you"
Les Earnest
repeat my earlier observation that I often ride my bike almost
effortlessly at over 66,000 miles/hour by using the Earth to pace me
in its orbit around the Sun.
--
Les Earnest Phone: 415 941-3984
Internet: L...@cs.Stanford.edu USMail: 12769 Dianne Drive
UUCP: . . . decwrl!cs.Stanford.edu!Les Los Altos Hills, CA 94022
BRANDT_JOBS...@hplomg.hpl.hp.com
> You mean to tell me that these guys actually convinced
> you of that BS about the bike being drawn along by the
> 'wind' from the 18 wheeler? :-)
I assume you jest but in the event that you are serious I should ask
whether you ever rode in a convertible car. If you did this at an age
where you had reasonably long hair you must have noticed the strong
forward draft and that at 30 mph it is strong enough, if applied to a
bicyclist, to propel him without assistance. Now, a convertible car
is not designed specifically to do this so you can imagine that if one
were to do some aerodynamic designing, the effect could be substantially
increased. Because these effects increase as the square of velocity
while rolling resistance increases linearly, it should be evident
that at higher speeds pedaling to propel the bicycle goes to zero and
ultimately backpedaling or braking becomes necessary.
As I stated, John Howard was towed to a substantial speed (100+ mph if
I recall correctly) before "cutting loose". At speed his 20 inch wheels
were turning about 2500 rpm and with a cadence of 200 that would require
a gear ratio of 12.5:1 with a double reduction chain (as he had). I don't
recall the ratio but it was in this magnitude. At this speed and a foot
to road ratio of 1:19, a 10 pound pressure that a rider might exert on the
pedals at this speed becomes less than one pound forward propulsion. The
10 pound estimate is most likely high since pedal force goes to zero at
the limit of spin as is apparent from riding rollers in a small gear at
such a cadence.
That controlling a bicycle in turbulent air behind a wind screen is
difficult and dangerous is not disputed. My point is that the rider in
these events does not contribute to propulsion and that the pedals are
merely a device to make the concept of someone "riding a bicycle" at such
speeds palpable.
Jim Moore
>Regarding the claims that paced records have some significance, let me
>repeat my earlier observation that I often ride my bike almost
>effortlessly at over 66,000 miles/hour by using the Earth to pace me
>in its orbit around the Sun.
Most other riders do this as well - the penalty for getting dropped
is very severe.
jim
Dennis Allard
> Why on earth would he design a fairing that "only eliminates wind drag"
> We are talking, after all, about a guy who not only holds the record for
> the transcontinental ride but also spends record amounts each time he
> ...
> Not that there's anything wrong with that per se ...
OK, let's keep this ridiculous thread going for awhile.
First of all, just because I have tail wind does not mean I get a free
ride. I've ridden in damn strong tail winds and still was able to
spin fast enough that I was going anerobic.
Could we change this into a thread on "The effects of tail wind"? Does
anyone care enough to dredge up the facts about what power output you
need to maintain a given road speed on the flat, given different
tail wind velocities? (Jobst spent at least three paragraphs worth of
time typing into this thread, so maybe he has some data like that handy
which he could paste in and share with us, for example).
Dennis Allard
all...@isi.edu
Thomas H. Kunich
negligable in these record attempts. I think that the
figures I saw showed that a rider would have to be up
around 200 mph before he started being limited by
rolling resistance alone.
The turbulent flow of the air around the windshield of
a convertable is hardly of the order of magnitude to
give any substantial assistance to a bicyclist and "correctly"
designed fairings are worse in this respect, not better.
The limitations of speed by motorpacing are in the vehicles
that are pacing, not in the rider per se'.
You are quite correct that motor-paced records are tricky
and don't prove much.
Thomas H. Kunich
that had to do with turbulent flow effects and the
vortices formed from it. Believe me that there is no
such thing as a stable vortex in the regimes discussed
here.
Daavid Turnbull
is an average of about 50kph.... maybe what he was riding wasn't person
powered.
--
Daavid Turnbull
daa...@bohra.cpg.oz +61 3 823 0222 (fax) +61 3 824 8068
uunet!munnari!bohra.cpg.oz!daavid
CP Software Export Pty Ltd ACN 006 640 133
BRANDT_JOBS...@hplomg.hpl.hp.com
< Harry -- the rolling resistance of a bicycle tire is negligible in these
< record attempts. I think that the figures I saw showed that a rider would
< have to be up around 200 mph before he started being limited by rolling
< resistance alone.
{you mean 100, I assume}
Rolling resistance may be negligible at pedestrian speeds but the power goes
up as the velocity and is about 1/2 HP at 150 mph (220 ft/sec).
< The turbulent flow of the air around the windshield of a convertible is hardly
< of the order of magnitude to give any substantial assistance to a bicyclist
< and "correctly" designed fairings are worse in this respect, not better.
My example was intended more to demonstrate that forward airflow can be
generated even by a wind screen that is not intended to do so more than to
imply that one could set a world record that way. However, if the wind
force produced by a car windshield were applied to the entire back of a
bicyclist, it would probably suffice to propel him at high speed. The force
of this wind increases with the speed of the car.
What do you mean by "correctly"? When I say correctly I mean a wind screen
that is designed to aid in the propulsion of the bicyclist with suitably
mixed air to avoid wave motion and upsetting instabilities.
Your line of argumentation reminds me of the writers who also argued that
tires on a road cannot exceed a friction coefficient of 1.0 in spite of
pictures of motorcycles leaning at 2 G's and bicyclists leaning at 1 G.
I can assure you that just making still air relative to the pace car's
speed is not enough to allow bicycle speeds of even 100 mph, much less
150+ mph. Maybe you should restate what your contention is about paced
bicycling instead of suggesting others are wrong about it. I for one do
not know what it is you proposed.
Thomas H. Kunich
have gotten the gist of my meaning:
You _cannot_ (as in can NOT) maintain a constant vortex behind
a wind screen of the sort necessary to allow a vehicle to
drive up to and above 100 mph or even 50 mph.
Although I forget all of the proper terminology, the vortices behind
the fairings are formed in alternating pairs and peel off
to form a votex "street" behind the moving object. The forward
moving air is a _very_ small percentage of the passing air velocity
because the power is coupled through viscous drag of the air, which
as you know is notoriously inefficient (if it wasn't wind would
blow everywhere all of the time!)
The effect on a cyclist that was in the vortex forming region would
be to feel turbulent wind alternating from one side then the other.
The buffeting would be rather serious and no rider would be able to
maintain control at higher speeds.
Since these vortices form _behind_ the moving object there
is a boundary layer of _dead_ air directly behind the object and
the vortices form behind this dead air space. As speed increases
(and if the fairing is "streamlined") the vortex energy will
grow enough to begin spawning vortices theirselves further in.
These vortices are normally trapped between the fairing and
the trailing vortex structures.
The power in the portion of the vortex moving forward is infinitesimal
compaired to the energy required to propel the rider, overcome
the rolling resistance and allow the rider to keep control during
the turbulence inevitably leaking around the fairing.
Believe me when I tell you that I am perfectly aware of the physics
of this problem. I just spent five months working out a flow lab
that dealt with exactly this problem.
Les Earnest
>You _cannot_ (as in can NOT) maintain a constant vortex behind
>a wind screen of the sort necessary to allow a vehicle to
>drive up to and above 100 mph or even 50 mph.
Gee, I wonder how they do it then? Will someone in Berzerkely please
give Tom a ride in a convertible so that he can figure this out?
. . .
>Believe me when I tell you that I am perfectly aware of the physics
>of this problem. I just spent five months working out a flow lab
>that dealt with exactly this problem.
Sure, Tom, we believe you. ;-)
Thomas H. Kunich
of your convertible and see if it passes you up as you drive sedately
down the street.
Since you and Jobst think that setting motor-paced records
requires no energy from the rider at all then I suggest that
you set a few world records.
What I'm reading is people who appear to be saying that since
their hair gets blown around in a convertible and it doesn't
fly straight back, then there must be enough power here to
drive a bicycle to _any_ speed that the pace vehicle can achieve.
OK, let's see some of this. Motor-paced records are popular in Europe.
But I guess those Europeans are so stupid that they can't get it right
because it took John Howard to break the speed record.
Let's see you guys break it. I've got $1,000 that says that Brandt
can't do it.
George Dibos
This is more like it. Thanks for cutting to the chase, Tom. I dropped
out of this thread when it turned into religious pseudo science, but this
will take care of that.
Well, Mr. Brandt? And I think Tom will agree with me that we'd like to
see you do it WITHOUT pedals, too, since they were put there "only so
it would bear more of a resemblance to cycling", or however it was that
you described John Howard's record.
I think I'll call Mike S. tonight, to see what he thinks of all this, as
well.
BRANDT_JOBS...@hplomg.hpl.hp.com
> Although I forget all of the proper terminology, the vortices behind
> the fairings are formed in alternating pairs and peel off
> to form a votex "street" behind the moving object. The forward
> moving air is a _very_ small percentage of the passing air velocity
> because the power is coupled through viscous drag of the air, which
> as you know is notoriously inefficient (if it wasn't wind would
> blow everywhere all of the time!)
In spite of forgetting "proper terminology" the rest of the item is
filled with more than enough obfuscating jargon to "blow away" the
aerodynamic illiteracy of the rest of us net readers. I am not
impressed. Paraphrasing Feynman, "If you can't explain it in plain
English you probably don't understand it yourself", probably fits
here especially well.
I also don't care what problem Tom has worked on for weeks, be that
rocket propulsion or detecting neutrinos, it doesn't have anything to
do with wind screens for motorpacing.
A wind screen can be made that directs substantial forward air with
respect to the moving vehicle and this air can be disturbed by
directed vanes so that it cannot buffet the rider with large waves
if unstable currents. Typically, riding behind a tractor and trailer
combination, the turbulent air from under the vehicle mixes with
the eddies from around the sides to produce a fairly comfortable
bicycling environment. This is not a dead air space but rather a
zone with forward moving air that circulates in swirls behind the
truck. It mixes at the edges with incoming air as can be observed
from behind when pieces of paper get caught in it. The paper often
takes several laps in the swirling air before escaping.
Of course there are many other ways of showing that there is more
then dead air behind John Howard's wind screen. I have never heard
anyone riding rollers at 150 mph with or without disk wheels.
Howard's wheels were not disks.
Dennis Allard
> I think I'll call Mike S. tonight, to see what he thinks of all this ...
Oh please do. It would be wonderful to post his opinion about all
this. Read him one of Jobst's postings.
(After intially falling prey to Jobst et. al's arguements, I am now
ununconvinced as to the merits of paced records.)
Dennis
David Olson
An excuse to mention a really cool picture book about fluid flow!
Look at *An Album of Fluid Motion* compiled by Milton Van Dyke.
Fabulous pictures! You can get it from Parabolic Press,
PO Box 3032, Stanford, CA 94305-0030.
to...@netcom.com (Thomas H. Kunich) writes:
>Although I forget all of the proper terminology, the vortices behind
>the fairings are formed in alternating pairs and peel off
>to form a vo[r]tex "street" behind the moving object. ...
I presume you are referring to a "Karman vortex street." That's a 2D
flow where swirls shed off alternating sides of a cylinder. I'm
already skeptical of the relevance to a motor-paced bicycle.
I think you need to be more exact in describing which situation you
studied. 2D or 3D? Reynolds numbers? Mach number? Shapes of the
objects? etc.
>...Since these vortices form _behind_ the moving object there
>is a boundary layer of _dead_ air directly behind the object and
>the vortices form behind this dead air space. As speed increases
>(and if the fairing is "streamlined") the vortex energy will
>grow enough to begin spawning vortices theirselves further in. ...
Sounds confused. You call a wake a boundary layer? That doesn't
exactly buttress your claim to Superior Knowledge. Since "streamlined"
appears to be one of your assumptions, don't you worry that not so
streamlined objects might lead to different flows?
david
Thomas H. Kunich
>
>An excuse to mention a really cool picture book about fluid flow!
>Look at *An Album of Fluid Motion* compiled by Milton Van Dyke.
>Fabulous pictures! You can get it from Parabolic Press,
>PO Box 3032, Stanford, CA 94305-0030.
Ah! That was one of my sources. Careful examination of the pictures
will reveal that at most reynolds numbers the fluid flow behaves
essentially identical.
>I presume you are referring to a "Karman vortex street." That's a 2D
>flow where swirls shed off alternating sides of a cylinder. I'm
>already skeptical of the relevance to a motor-paced bicycle.
For some reason I seemed to remember von Karman vortex street. You
seem to have the idea that there is a distinction between between
2D and 3D vortices in these tests. Can you tell me how they developed
these vortices in two dimensions?
>
>Sounds confused. You call a wake a boundary layer? That doesn't
>exactly buttress your claim to Superior Knowledge. Since "streamlined"
>appears to be one of your assumptions, don't you worry that not so
>streamlined objects might lead to different flows?
>
I don't claim "Superior Knowledge" at all. I am disputing the
preposterous claims of Jobst and Les that motor-pacing requires
no strength or skill on the part of the bicyclist.
Exactly what would you can the dead air space behind _any_ shape
in three dimensions? If you want to quibble that it isn't part of
the boundary layer, go right ahead.
BTW there are some pretty good photos of spheroid objects in the
flow that reveal that the more streamlined the object the less
dead air space there is behind. My direct measurements of the
fluid speed showed that there was esentially no power in this
vortex area.
So, like Jobst and Les, I'll bet you $1,000 that you can't break the
world bicycle speed record without pedalling. Since you are all
convinced that motor-pacing is done with mirrors and smoke this
should be very easy for you to accomplish and a quick and easy 1 G.
Gregg Mack
> [...] I have never heard
>anyone riding rollers at 150 mph with or without disk wheels.
>Howard's wheels were not disks.
>
>jobst_...@hplabs.hp.com
Jobst,
Could the gear ratios have anything to do with this?
--
Gregg Mack --------- __o __o __o __o
gm...@hobbes.sps.mot.com ------- _`\<,_ _`\<,_ _`\<,_ _`\<,_
Motorola RISC uProcessors ------ (*)/ (*) (*)/ (*) (*)/ (*) (*)/ (*)
Austin, TX USA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Harry Phinney
: no strength or skill on the part of the bicyclist.
Then you are disputing a claim which neither of the referenced authors
made. What they claimed was that there is no correlation between the
speed a cyclist achieves in a motorpaced attempt and the strength of
the rider. I have not seen anyone denigrate the skill necessary for
such an attempt.
I personally find it _very_ difficult to believe that professional
cyclist Jose Meiffret (sp?) was significantly weaker than former
motorcycle racer Dr Allan Abbott, who broke Meiffret's record by about
15 mph. I also sincerely doubt that even John Howard could produce
enough power, while wearing full motorcycle leathers and full face
helmet, to overcome the rolling resistance of his motorcycle tires on
the salt flats at 150 mph, not to mention the drag of the wire spoked
motorcycle wheels running 150 mph in "dead air". As someone (Jobst?)
pointed out, people have not done 150 mph on rollers, which undoubtably
have less rolling resistance than did Howard's bike.
: So, like Jobst and Les, I'll bet you $1,000 that you can't break the
: world bicycle speed record without pedalling. Since you are all
: convinced that motor-pacing is done with mirrors and smoke this
: should be very easy for you to accomplish and a quick and easy 1 G.
A quick 1G? Only if you already have a vehicle capable of pushing a
very large fairing at 150+ mph safely, and can pay for the use of the
salt flats, and the use of the timing equipment, and the observing
officials, etc. No, it's not a quick way to make 1G. It's at best a
daring way to spend tens of thousands of dollars.
Harry Phinney ha...@hp-pcd.cv.hp.com
BRANDT_JOBS...@hplomg.hpl.hp.com
> Tell you what Les, try laying a 5 lb. lead brick on the back seat
> of your convertible and see if it passes you up as you drive sedately
> down the street.
This kind of technical talk is about as deep as you can expect from a
sophist like Tom who tries, with a flood of jargon, to convince us of
his expertise in this field. Besides lead bricks weigh 26.3 lbs.
There is a standard for these things and they are 2x4x8 inches and
have a density of 11.35 gm/cc.
> Since you and Jobst think that setting motor-paced records
> requires no energy from the rider at all then I suggest that
> you set a few world records.
This is a common ploy. Take the words out of context and add some
words of your own and attribute it to the opposing point of view.
No one said it takes NO energy. But propulsion energy by the rider
is not used to achieve any of his speed.
> What I'm reading is people who appear to be saying that since
> their hair gets blown around in a convertible and it doesn't
> fly straight back, then there must be enough power here to
> drive a bicycle to _any_ speed that the pace vehicle can achieve.
Either you have no hair or no convertible in which to experience this.
I didn't say "blown around". I said blown forward. If you sit in the
back seat you will see the people in front as having a bald spot at the
center of pressure (depending on the car). The hair is blown straight
forward.
> OK, let's see some of this. Motor-paced records are popular in Europe.
> But I guess those Europeans are so stupid that they can't get it right
> because it took John Howard to break the speed record.
I don't know what this means. It seems like a gratuitous insult to
Europeans.
> Let's see you guys break it. I've got $1,000 that says that Brandt
> can't do it.
Oh great, now the music critics must be able to conduct and write
symphonies, the referees must play the game and the gymnastics judges
must earn gold medals. Great logic. As children often say "let's see
you do any better" when they disagree with a critic. Besides, I am not
claiming the motor-paced events didn't take place. I am explaining how
the results are achieved.
So let's look at some easily calculated numbers. If we assume that
the bicycle is moving at 150 mph (220 feet/sec) the thrust of 1/2 hp
equals 1/2 hp/220 ft/sec or (275 ft lb/sec)/(220 ft/sec = 1.25 lbs force
assuming no losses. Taking off 0.5 lbs for RR that leaves 3/4 lbs for
propulsion. With the gearing used, this is not enough to accelerate
from 100 to 150 mph in the length of the speedway. Something had to be
pushing.
David Olson
>In article <olson.713066349@acf9> ol...@acf9.nyu.edu (David Olson) writes:
I notice you didn't answer questions about your experimental set up--why?
Think a little bit and see if you can come up with a fairing design
that will drive energy into a recirculating wake using pressure
instead of viscosity. If nothing else, Jobst ought to have convinced you
that a motor paced rider (e.g. Howard) must have another source of energy
other than pedalling.
>You seem to have the idea that there is a distinction between between
>2D and 3D vortices in these tests. Can you tell me how they developed
>these vortices in two dimensions?
The most recent method I've seen used a long cylinder, with clever things
done near the ends to keep the flow essentially two dimensional for a
lot longer than earlier work. The whole point of this work is to study
the vortex street, which is a 2D phenomenon. Your bringing up the term
in connection with 3D flows is essentially "name-dropping," I talked to
LeMond about it, and he thought it was rather obvious and shallow.
>Exactly what would you can the dead air space behind _any_ shape
>in three dimensions? If you want to quibble that it isn't part of
>the boundary layer, go right ahead.
:^) The popular term is "wake."
Thomas H. Kunich
>
>Then you are disputing a claim which neither of the referenced authors
>made. What they claimed was that there is no correlation between the
>speed a cyclist achieves in a motorpaced attempt and the strength of
>the rider. I have not seen anyone denigrate the skill necessary for
>such an attempt.
Then you haven't been reading Harry. Jobst said that there was no
need for pedals since there was no need for pedaling.
Thomas H. Kunich
>
>The most recent method I've seen used a long cylinder, with clever things
>done near the ends to keep the flow essentially two dimensional for a
>lot longer than earlier work. The whole point of this work is to study
>the vortex street, which is a 2D phenomenon. Your bringing up the term
>in connection with 3D flows is essentially "name-dropping," I talked to
>LeMond about it, and he thought it was rather obvious and shallow.
If you think tha there is such a thing as a 2D liquid flow then I suppose
anything could be possible. And since you consider the idea of the
vortices alternately dropping off to be unimportant to the conditions
behind the fairing I suggest that you are wrong. And by the way, I didn't
mention the name, I said vortex street. Your attempt to obfusticate
the subject isn't working very well.
>
>:^) The popular term is "wake."
A wake is the entire disturbed structure behind a moving body, not
the portion of dead space directly behind that body.
I you think that you can ride a bike at 150 mph behind a fairing
which supplies _all_ of the necessary power and doesn't require
pedal input power then I suggest you try it.
Some other person suggested that it was expensive to have a vehicle that
could do 150 mph. OK let's see you do 100. You don't need the salt flats
nor an official timer and vehicles that can push a bicycle fairing through
the air at 100 mph are readily available.
Thomas H. Kunich
since the invention of the motor vehicle. Now we find out
from you that the guys who can hardly achieve and hold 45 mph
for hours on end don't need to even pedal. In fact, contrary
to your last message, you have stated catagorically that John
Howard and the other attempts didn't even need pedals!
What I want to know is how you can construct such a fairing
while all this time those stupid europeans who could make
a lot of money doing this haven't been able to.
Is it because of your superior knowledge of aerodynamics or
is it that you are saying that all of these riders have been faking
the pain and exhaustion?
gregory adkins
>
(technical stuff about vortices and liquid flow deleted)
>
>I you think that you can ride a bike at 150 mph behind a fairing
>which supplies _all_ of the necessary power and doesn't require
>pedal input power then I suggest you try it.
>
>Some other person suggested that it was expensive to have a vehicle that
>could do 150 mph. OK let's see you do 100. You don't need the salt flats
>nor an official timer and vehicles that can push a bicycle fairing through
>the air at 100 mph are readily available.
150 sounds like more fun. I'll tie some plywood behind my
motorcyle and we can all go for a nice Sunday ride.
----------------------------------------------------------------------------
Greg Akins | "Life may be not only meaningless,
ak...@cis.ohio-state.edu | but absurd." -Thomas Nagel
____O __O "Saturn Floats"
_`___\-' / /\_, |
(')\/(`) ___/\ |
/_ |
--------------------------------------
Chris Moll
>I also sincerely doubt that even John Howard could produce
>enough power, while wearing full motorcycle leathers and full face
>helmet, to overcome the rolling resistance of his motorcycle tires on
>the salt flats at 150 mph, not to mention the drag of the wire spoked
>motorcycle wheels running 150 mph in "dead air". As someone (Jobst?)
>pointed out, people have not done 150 mph on rollers, which undoubtably
>have less rolling resistance than did Howard's bike.
Rollers may not produce more power loss at the tire/roller junction,
but what about losses in the rollers themselves? The rubber belt
between front and rear clearly disipates substantial energy, since it
gets hot if you do sprints. Imagine what would happen to the belt if you
tried to reach 150 mph.
It's a fair amount of work to ride rollers at 30 mph indicated -
significantly more, I would guess, than is needed solely to overcome
rolling resistance at 30 mph actual.
Shouldn't it be pretty easy to figure this out? What is the rolling
resistance of two motorcycle tires at 150 mph? Surely someone can come
up with real numbers as opposed to speculation about fluid models that
may or may not be relavent.
--
Chris Moll (510)486-7891
---
"Blessed are they who Go Around in Circles, for they Shall
be Known as Wheels."
BRANDT_JOBS...@hplomg.hpl.hp.com
> Could the gear ratios have anything to do with this?
[about no one ever riding 150 mph on rollers]
No! And no one has even gone 100 mph. Now that you mention it, I think
it would be a great idea to see how fast Howard's bike could be ridden
on rollers. I suspect, not at all, because the gear is so high that no
one could get it moving enough to stay up.
George Dibos
under the subject "Aerodynamics & Motorpacing" (or something similiar),
for the sake of clarity.
The only connection this originally had with ultra marathoning was
that a noted ultra marathoner also held some motorpaced records.
I would like to contact other ultra marathoners, and don't want to
"lose" them via kill file to an esoteric debate (though I am interested
in it myself).
Thanx
Harry Phinney
: while all this time those stupid europeans who could make
: a lot of money doing this haven't been able to.
This point shows quite well that the speed attained in motor pacing is
in the very least heavily dependent on the aerodynamic characteristics
of the lead vehicle. The motor paced track events use dernies of
specified dimensions, with no fairing, and with the trailing rollers
positioned a specified distance from the dernie rider. These rules are
in place specifically to limit the speeds attainable to keep the events
reasonably safe on existing velodromes. They are far from being "run
what ya brung" events.
Harry Phinney ha...@hp-pcd.cv.hp.com
Thomas H. Kunich
>They are far from being "run
>what ya brung" events.
Maybe you ought to direct this message to Alfa Romeo who
sponsored several LSR (bicycle) attempts using all of their
formidable technology.
Bicycle speed records have been heavily sponsored and much
money has been expended in them. Now we find out from
Jobst and Les Ernest that there isn't even any need for
pedals. Obviously these people need the True Experts (tm)
to run these projects.
Or maybe you don't recall Jobst telling us that the reason that
Howard was using a fixed gear was because he didn't want anyone
to see him freewheeling at high speed and finding out that he
didn't need to pedal at all. We won't mention that it was probably
much easier for him to build a gigantic gear set with a fixed
gear. Nope, this gear was used to fool us mere childish idiots
into believing that it actually takes strength, endurance and
skill to achieve a world land speed record.
And if you read Jobst previous post about the numbers I think
that the slightest reflection would have shown you that there
was an excess of power at 150 mph -- that would be the power to
overcome the rolling resistance and the slight turbulence behind
the fairing. So Jobst actually proved my point. (One has to wonder
what he meant by accelerating though since his figures were for
steady state of a body _already_ at 150 mph.) Or in other words;
Jobst showed that the rider would have to be generating about
1/2 horsepower for the duration of the run. This is no mean task.
Bruce Hildenbrand
>Tom Kunich writes:
>
>> What I'm reading is people who appear to be saying that since
>> their hair gets blown around in a convertible and it doesn't
>> fly straight back, then there must be enough power here to
>> drive a bicycle to _any_ speed that the pace vehicle can achieve.
>
>Either you have no hair or no convertible in which to experience this.
>I didn't say "blown around". I said blown forward. If you sit in the
>back seat you will see the people in front as having a bald spot at the
>center of pressure (depending on the car). The hair is blown straight
>forward.
>
I would like to add to Jobst's observations and say that I used to do
a lot of motorpacing and I was extremely suprised when I noticed that
the sweat dripping off my forehead traveled forward, towards the
rear of the car I was drafting, instead of flying back behind me as one
would expect at 40mph. Clearly, something was pushing the sweat
forward, I assumed(correctly or otherwise) that it was the wind vortices
coming off the back of the car.
A few weeks back, I took Jobst to task for several of his postings, but
at times like this, I am glad he is on the net.
I don't think anyone is saying that John Howard is a wimp and doesn't
deserve any credit/respect for his efforts. IMHO, it took great skill
and courage to draft that dragster at 150mph knowing that one little
bobble or mistake could potentially cost you your life. Way to go,
Howie!
Bruce
Harry Phinney
: sponsored several LSR (bicycle) attempts using all of their
: formidable technology.
The only serious attempts I am aware of since John Howard's ride have
been made by a European rider (whose name escapes me) with John Howard's
assistance. These record attempts depend heavily on outside factors
such as the condition of the salt flats (which varies a lot seasonally
and year-to-year), weather, and luck. As I remember, the current
contender took an extremely high speed fall which set back his plans a
bit. Nobody here has claimed that setting this record is technically
easy, or safe. There is a hell of a lot of work that goes into such a
record run, but most of it concerns the lead car, the course, and
control of the two vehicles, not the rider's fitness.
: We won't mention that it was probably
: much easier for him to build a gigantic gear set with a fixed
: gear.
He assembled custom built bike with motorcycle geometry and wheels, with
an intermediate gearing jack shaft, but a freewheel is too complex? I
don't think so. I personally don't know why Howard chose to use a fixed
gear, but I don't believe ease of construction played a significant
role.
: Or in other words;
: Jobst showed that the rider would have to be generating about
: 1/2 horsepower for the duration of the run. This is no mean task.
I haven't checked his numbers, but I believe what he was attempting to
show was that 1/2 horsepower was insufficient to accelerate Howard and
his bike from 100 mph to 150 mph within the length of the run at
Bonneville.
Harry Phinney ha...@hp-pcd.cv.hp.com
Thomas H. Kunich
> Nobody here has claimed that setting this record is technically
>easy, or safe.
I guess you think that saying that the rider doesn't even need to pedal
doesn't qualify as saying that it was technically easy?
.
>I haven't checked his numbers, but I believe what he was attempting to
>show was that 1/2 horsepower was insufficient to accelerate Howard and
>his bike from 100 mph to 150 mph within the length of the run at
>Bonneville.
>
I only looked briefly at his numbers and thought about it later.
It appeared to me like he was giving the power needs for a steady
state of 150 mph and then began talking about there being insufficient
power to accelerate from there. I agreed with that.
Let's get the conversation straight here. I agree with Jobst that
there is nothing significant proven by motor-paced World Land
Speed Record attempts successful or not. This is more of a technical
exercise in building a motor vehicle, not the bicycle.
But motor-pacing is an old form of racing in this world and the
laws of physics that control it are well known. You cannot build
a fairing that doesn't require the bicyclist to input considerable
energy at those high speeds.
Again, this exact conversation went on between scientists far more
talented than us as far back as 1895 when Mile-a-minute Murphy set
his "astounding" record. Why is this being rehashed?
I'm not sure, but I seem to recall that the 'roller' speed record
is some preposterously high speed like 220 mph. So this would
pretty much indicate the rolling resistance of a bike is pretty small
compared to the power output of the rider.
sidd...@austin.ibm.com
Yawn....
Derick Siddoway
David Olson
>In article <olson.713155890@acf9> ol...@acf9.nyu.edu (David Olson) writes:
>>
>>The most recent method I've seen used a long cylinder, with clever things
>>done near the ends to keep the flow essentially two dimensional for a
>>lot longer than earlier work. The whole point of this work is to study
>>the vortex street, which is a 2D phenomenon. Your bringing up the term
>>in connection with 3D flows is essentially "name-dropping," I talked to
>>LeMond about it, and he thought it was rather obvious and shallow.
>If you think tha there is such a thing as a 2D liquid flow then I suppose
>anything could be possible. ...
OK. Now I'm convinced that you're a fluid tourist, not an expert.
Just checking.
>And by the way, I didn't mention the name, I said vortex street.
That's name dropping.
toodles. I have to move today.
Timothy Smith
>Let's get the conversation straight here. I agree with Jobst that
>there is nothing significant proven by motor-paced World Land
>Speed Record attempts successful or not. This is more of a technical
>exercise in building a motor vehicle, not the bicycle.
FINALY! An end is near for this thread...
>But motor-pacing is an old form of racing in this world and the
>laws of physics that control it are well known. You cannot build
>a fairing that doesn't require the bicyclist to input considerable
>energy at those high speeds.
NOT! It is very possible to build a fairing which requires NO power
input at a critical speed, and negative power input at higher speeds.
I have Emailed you the reasoning, and you ignore it. Well, here it is
for the net:
Point one:
Building a fairing which has significant recirculation is a trivial
excercize for any COMPETENT aero engineer. Actualy, the hard task is
building a fairing which has dead air behind it. (As Jobst has pointed
out, the convertible manufacturers haven't figured this out out yet.
Wouldn't a convertible which didn't muss hair be technicaly superior?)
Point two:
Aero resistance scales with the square of the air velocity. Rolling
resistance is more or less constant. The thrust required at speed is
equal to the sum of the rolling resistance and the aero resistance.
If there is recirculation in the fairing then the aero resistance is
negative. So, assuming recirculation;
Thrust required = RR - Const*V^2
So, the thrust required is zero when the speed reaches
V_critical = sqrt(RR/Const)
At speeds higher than V_critical the thrust required is NEGATIVE!
The rider would have to use his brakes to keep from hitting the pace
car. (Perhaps that's why Howard used a fixed gear...so that he could
control his position WRT the pace car AT SPEED.)
>Again, this exact conversation went on between scientists far more
>talented than us as far back as 1895 when Mile-a-minute Murphy set
^^
>his "astounding" record. Why is this being rehashed?
Speak for yourself - white boy!
As for why it is being rehashed, well I don't know. Perhaps it's
because YOU keep posting technical garbage as fact, and those of US
who know better have to respond.
Tim Smith
Tim Moore
In rec.bicycles, to...@netcom.com (Thomas H. Kunich) writes:
>But motor-pacing is an old form of racing in this world and the
>laws of physics that control it are well known. You cannot build
>a fairing that doesn't require the bicyclist to input considerable
>energy at those high speeds.
NOT! It is very possible to build a fairing which requires NO power
input at a critical speed, and negative power input at higher speeds.
I have Emailed you the reasoning, and you ignore it. Well, here it is
for the net:
Here we go again.
To inject some data into this amazing thread, I looked up the
stationary roller record in a 1986 Guiness Book of World Records this
weekend. As of that edition the record, set in 1979 by an Englishman
whose name escapes me, was 102 mph for 200 meters. I doubt the record
has been improved since then.
With the disclaimer that rollers may impart more rolling resistance
than salt flats, this would seem to be an approximate upper bound for
bicycle speed in "still" air.
--
Tim Moore mo...@cs.utah.edu {bellcore,hplabs}!utah-cs!moore
"Wind in my hair - Shifting and drifting - Mechanical music - Adrenaline surge"
- Rush
Thomas H. Kunich
>input at a critical speed, and negative power input at higher speeds.
Tim, this is very easy to prove. There are all sorts of sponsors
out there waiting for these "competent aerodynamics engineers" that
you speak so highly of. Let's see it.
I want some real world proof and not some theorizing by someone
that hasn't done it.
Les Earnest
>A wake is the entire disturbed structure behind a moving body, not
>the portion of dead space directly behind that body.
Actually, a wake is a gathering to pay tribute to a formerly moving
body that recently became dead.
>Some other person suggested that it was expensive to have a vehicle that
>could do 150 mph. OK let's see you do 100. You don't need the salt flats
>nor an official timer and vehicles that can push a bicycle fairing through
>the air at 100 mph are readily available.
I guess that Tom refuses to recognize the 66,000+ mph speed that we
achieve each time we ride. It appears that he considers it OK to take
pace behind a racing car with a windscreen but not to take pace from
the earth.
I propose that we hold a wake for the silly discussion of paced records,
then take an oath of silence on this topic.
--
Les Earnest Phone: 415 941-3984
Internet: L...@cs.Stanford.edu USMail: 12769 Dianne Drive
UUCP: . . . decwrl!cs.Stanford.edu!Les Los Altos Hills, CA 94022
BRANDT_JOBS...@hplomg.hpl.hp.com
> Jobst, there have been motor-paced events in Europe almost
> since the invention of the motor vehicle. Now we find out
> from you that the guys who can hardly achieve and hold 45 mph
> for hours on end don't need to even pedal. In fact, contrary
> to your last message, you have stated catagorically that John
> Howard and the other attempts didn't even need pedals!
True to form. You change the subject and as a true sophist proceed
to draw in irrelevant matter. It was never stated that motor-paced
racing required no skills and no pedaling or any other far fetched
idea of the usual Kunich style. We are talking about land speed
records for bicyclists behind specially constructed "wind screens".
Wind screens that are specifically designed to assist the bicyclist
to achieve a speed that exceeds any conceivable power that a human
can produce, even for a short burst let alone the time and distances
of a record attempt.
> What I want to know is how you can construct such a fairing
> while all this time those stupid europeans who could make
> a lot of money doing this haven't been able to.
I don't know what you have against Europeans, Tom, but I don't find
them less intelligent than inhabitants of other continents. You also
fail to see that you can't make "a lot of money doing this". In fact
it *costs* much money, and advertising sponsors are not as generous
in Europe as in the USA. Besides, Howard is not a rich man for his
efforts.
> Is it because of your superior knowledge of aerodynamics or
> is it that you are saying that all of these riders have been faking
> the pain and exhaustion?
Your insulting style is tiring. The conclusions you draw from what I
and others have written bear little resemblance to what was said.
Your diversions have a pointedly insincere inquisitive tone that with
repetition exceed the bounds of courteous discourse. You find no
problem with name calling for which you will probably receive the
same from others if you persist.
BRANDT_JOBS...@hplomg.hpl.hp.com
> I'm not sure, but I seem to recall that the 'roller' speed record
> is some preposterously high speed like 220 mph. So this would
> pretty much indicate the rolling resistance of a bike is pretty small
> compared to the power output of the rider.
Well I was foolishly thinking of conventional bikes on so-called racing
rollers. No doubt a roller and wheel combination can be and probably has
been built that allows even higher speeds than the number Tom quotes.
A special roller bike with 10 inch diameter metal disks having a thin
rubber tread running on rollers with light weight oil and a shaft drive
to the front roller could, with little effort reach these speeds. As
motor paced land speed records, such a roller record has little athletic
significance. Technically it may be a challenge but the word
"preposterous" fits.
BRANDT_JOBS...@hplomg.hpl.hp.com
> Shouldn't it be pretty easy to figure this out? What is the rolling
> resistance of two motorcycle tires at 150 mph? Surely someone can come
> up with real numbers as opposed to speculation about fluid models that
> may or may not be relevant.
This is an errand suggested by someone else and can be estimated by pulling
a BMX bike with smooth tires with a fish scale. This has been done and it
runs in the order of 1/2 to 3/4 pounds force. RR remains essentially
constant but power goes up with speed because power is the product of drag
and speed. What is more convincing is that Howard's bike could not be
propelled by the rider at bicycle speeds because its drag is too great
for the gear ratio used so that when the pedals reach TDC the rider
loses balance. That is, you can't ride this bike. This, I believe, helps
put this into perspective. No doubt there are people who could balance the
bike but Howard is not an accomplished stunt or trials rider.
To understand how powerless a rider is at high speed one needs to coast
down a highway like Conway Summit where 50 mph is relatively safe and
easy. With a 52-11 you can see that all the effort you can put out
barely increases your speed over another rider coasting next to you. The
point is that when your propulsion power is in the range of several horse
power, your measly input is meaningless.
Gordon Lee Powell Jr
I can recall reading an account of one of Howard's speed attempts
in a bike mag. about eight years ago. He clearly was having the problem
of fighting the strong recirculation in the flow.
He had to keep a very steady position because of the unanticipated
recirculation flow. He recounted how there was a spot behind the car
with especially strong recirculation, and if he drifted back into it
it would throw him into the back end of the vehicle. He rebounded off
the back of the vehicle and hit the strong recirculation again to be
thrown into the pacer once again. I don't remember how long he
pogo'ed back and forth.
Mr. Smith is right, it is a difficult thing to come up with a fairing
that allows a large area of truly "dead" air behind the pacer.
Gordon L. Powell, Jr. '89 glp...@zeus.tamu.edu (VMS on VAX 9000)
Aero Engr Texas A&M Univ. gor...@aero.tamu.edu (D. U. on S. C.)
Oh well, some people can flame in a nitrogen environment.--Les Earnest
Timothy Smith
>In article <23...@oasys.dt.navy.mil> tds...@oasys.dt.navy.mil (Timothy Smith)
>writes:
>> NOT! It is very possible to build a fairing which requires NO power
>
>Tim, this is very easy to prove.
Well, I don't know what YOU consider a proof, Tom, but to most of
us real world evidence, along with a reasonably watertight mathematical
theory is sufficient.
I think the proof lies with you to give a theory on why the energy
of the freestream flow CANNOT wind up in the wake. What law of physics
prevents momentum exchange with the wake? What law of physics causes
the wake to experience exactly the same pressure on all boundaries?
>There are all sorts of sponsors
>out there waiting for these "competent aerodynamics engineers" that
>you speak so highly of. Let's see it.
Ahh, the "Thomas H. Kunich" proof by intimidation. Who could ask
for more?
let me turn this around to you: If there are "all sorts of sponsors"
out there (for a recirculation enhancing fairing) then where are they?
I would LOVE to get some bucks for my lab to study this problem.
Why don't you get one of them to call me?
I can't think of a quicker and more profitable aerodynamic study.
>I want some real world proof and not some theorizing by someone
>that hasn't done it.
Take a look in the mirror, Tom.
First you claim that recirculation is impossible. Then people post
examples where recirculation definately exists. Then you pull strange
theories out of your A**, er, HAT. When these theories are disputed
by competent aerodynamicists you resort to "proof by intimidation."
What's next, the "NYE NYE I told you so!" argument?
The bottom line is that you were an electronic technition on an
aerodynamics project you didn't understand. Now you claim to be an
aerodynamics expert. Wise up and quit while you are behind - stick
to electronics.
Tim Smith
P.S. This thread is going into my kill file. I've spent enough time
arguing with Mr. Kunich.
Thomas H. Kunich
>
>He clearly was having the problem
>of fighting the strong recirculation in the flow.
I doh't deny that there is power added by the vortices that are present.
I have been arguing that Jobst statements that these records could be
set without resort to any power input by the rider whatsoever is a
great overstatement.
My position has been that the _main_ addition of the fairing is dead air
not additional power. And history certainly bears this out.
>
>Mr. Smith is right, it is a difficult thing to come up with a fairing
>that allows a large area of truly "dead" air behind the pacer.
I'm quite sure that he is right. I cannot see any way of designing
abody that doesn't generate vortices of some sort. The question is
whether or not they can add sufficient power to overcome the rolling
resistance. History says no.
Look, there appears to be enough agreement of a select group here
on this subject that you ought to be able to get together and build
a World Land Speed Record bicycle without pedals. I suggest you all try.
>
Harry Phinney
: whether or not they can add sufficient power to overcome the rolling
: resistance. History says no.
I have seen no such history. History has given us former motorcycle
racer Dr. Alan Abbott shattering the record held by a professional
bicycle racer. I have seen no correlation between the record speed and
the potential power output of the riders involved.
: Look, there appears to be enough agreement of a select group here
: on this subject that you ought to be able to get together and build
: a World Land Speed Record bicycle without pedals. I suggest you all try.
Your suggestion that such an attempt is simple and easily undertaken by
a random group of people is ludicrous. It literally takes tens of
thousands of dollars to make a serious effort to set such a record.
These costs have nothing to do with the bicycle itself or the rider, but
involve the lead vehicle, the course, the timing, and the officiating.
I have a much cheaper suggestion. Why don't you try motor pacing behind
a large vehicle (e.g. a van) at speeds around 50 mph, and try riding
in different areas behind the vehicle. I am quite confident that you
can find a region which provides a significant tail wind. Assuming this
to be the case, you would have to admit that you are, at that point, not
having to overcome all of the rolling resistance of the bike.
Harry Phinney ha...@hp-pcd.cv.hp.com
Mark Drela
That sounded like a dare. Well, go check out
"Flow over Surface-Mounted Semi-Bluff Bodies", P. Handford and P. Bradshaw,
in proceedings of 3rd Symposium on Numerical and Physical Aspects of Aerodynamic
Flows, Cal-State Long Beach, Jan 1985.
It presents detailed velocity measurements behind a body shaped like a half-bullet
(split lengthwise) and mounted flush on a surface. The maximum _backflow_
velocity measured is 25% of the freestream speed. If John Howard used this
shape for his pace car, he would have felt a 38 mph tailwind at the "sweet spot".
Assuming a drag area of 3.5 ft^2 (from Bicycling Science), this translates
to a forward push of about 13 lb. This is maybe 5x more than is needed to
overcome the rolling resistance of the small fat tires he used. Even with
spoke drag, most of the power delivered to Howard by the backflow probably
went into heating up his brake pads as Jobst theorized.
So there.
Can we give this a rest now?
Mark Drela
(aerodynamics engineer)
_______________________________
o/LO .'
O .' Gravity-Powered Technologies Lab
.' MIT Aero-Astro Department 33-214
'
John Kim
aerodynamics. However, I ask if it's possible that the people
who build such fairings, or who ride behind such trucks or race
cars, would prefer that the fairing not result in the rider
having to produce negative power input? After all, it seems from
Timothy Smiths logic that any such sucessfully fairing would
have some speed at which the rider did not have to pedal, and at
any higher truck speed the rider would have to apply the brakes or
backpressure on the pedasl. This would be annoying, in the least
for the long rides, and embarassing to be seen squeezing the
brakes for 400 miles, no? Besides, teh resulting pad wear
and heat buildup might cause problems.
Therefore I prpose that if I were steady enough to attempt
a 400-500 mile ride (or more) at over 50mph behind a large vehicle,
I would ask my "competent aerodynamics engineer" to try to
hold down the turbulence but also to make sure that at the
expected travelling speed I had to put in some small amount of
power to keep up with the truck. It seems to be (not having
tried it myself) that I would rather pedal in a really high
gear at an easy effort for hours on end while dodging potholes
and eating stuff rather than hanging onto the brakes for
hours on end (can't eat if both hands are on the brakes).
No bad reflection on teh guys who do this stuff. I
probably wouldn't be able to keep up such motorpacing at
even 40mph for more than an hour.
-J. Case Kim, no engineer
Thomas H. Kunich
>
> Well, I don't know what YOU consider a proof, Tom, but to most of
>us real world evidence, along with a reasonably watertight mathematical
>theory is sufficient.
I think that you might find that most people would consider actual
evidence to be the proof we're looking for. Not blind theorizing.
> Ahh, the "Thomas H. Kunich" proof by intimidation. Who could ask
>for more?
No, Tim, if you think that disagreement with a theory and asking for
hard evidence is intimidation then you should see real science at work.
> First you claim that recirculation is impossible.
This grows more and more preposterous. Not only have I never claimed
that recirculation is impossible, I originally started the conversation
about the vortices behind a moving body. You appear to be confusing
all of the string with something that I wrote alone.
>P.S. This thread is going into my kill file. I've spent enough time
>arguing with Mr. Kunich.
The strange part is that directly before this Tim was accusing me of
using the "NYAH, NYAH, I'm right and you're wrong" method of
arguing. I guess it takes all kinds.
Thomas H. Kunich
>I have seen no such history. History has given us former motorcycle
>racer Dr. Alan Abbott shattering the record held by a professional
>bicycle racer. I have seen no correlation between the record speed and
>the potential power output of the riders involved.
Hmm, Harry, I think that I have already written many times that
the _motor_vehicle_ is the significant variable below the point
at which rolling resistance is less than the power generated by
the rider. I agree with you completely that less than optimal power
is generated by the riders involved in these contests. Whether
because Dr. Abbott simply didn't have the legs or because John
Howard was handicapped by using a motorcycle helmet and racing
leathers is pretty inconsequencial compared to that vehicle.
>
>I have a much cheaper suggestion. Why don't you try motor pacing behind
>a large vehicle (e.g. a van) at speeds around 50 mph, and try riding
>in different areas behind the vehicle. I am quite confident that you
>can find a region which provides a significant tail wind. Assuming this
>to be the case, you would have to admit that you are, at that point, not
>having to overcome all of the rolling resistance of the bike.
Harry, I'm quite willing to believe that there is some power
input from the vortices formed behind a moving body. This entire
subject was started because Jobst told us that these record
attempt didn't even require the input of any power whatsoever
from the rider.
Look, you don't even need to set a world record, you don't need
a single official timer, you don't need the Bonneville flats.
Just design a fairing behind which a rider can go a significant
distance -- say a couple of miles -- without pedalling. To prove
this you should remove the chain.
Look, I'm easy to please. I don't have any ego problems with saying
that I'm wrong if I'm proven wrong. What I'm saying is that you can't
do this thing that Jobst stated and his supporters are saying that
he was correct and that my insisting that, if so, show me some
hard evidence, is unfair.
BRANDT_JOBS...@hplomg.hpl.hp.com
> Look, there appears to be enough agreement of a select group here
> on this subject that you ought to be able to get together and build
> a World Land Speed Record bicycle without pedals. I suggest you all try.
I'm glad you are looking out for us Tom, otherwise we might not have
any ideas on what to do. As your arrogant and condescending blurbs
continue to appear, I have become curious. From what real or imagined
defects do you suffer that make you feel inferior enough to piss on
anyone in this newsgroup.
> I think that you might find that most people would consider actual
> evidence to be the proof we're looking for. Not blind theorizing.
You don't seem to have much respect for science either by calling
anything that is not measured and recorded to be irrelevant, or worse
yet, theory. You probably don't believe in mathematics either unless
you can count the results on your fingers. In the event that the direct
approach might appeal to your nature, I'll suggest you take a trip to
the toilet and relieve yourself of the fecal matter that seems to be at
a level that interferes with your vision and speech.
Carl Gooch
As opposed to _your_ theorizing? I honestly have to wonder about your
credentials in fluid mechanics if you are unaware of the presence of a
recirculating region downstream of a blunt body. As an example, look
in Van Dyke's Album of Fluid Mechanics (which has been mentioned here
before) at flow over a backward-facing step. Behold, recirculation!
A square-backed fairing would have the same basic flow pattern. Since
the separation points are fixed by the corners of the body, unsteady
motion of the separation points (which for some other geometries leads
to a vortex street) never develops.
On the other hand, if you're entertaining yourself by watching
people's reactions to your posts, I'm sure you're having a great time.
Carl
--
------------------------------------------------------------------------------
Carl Gooch | Why am I inside at a keyboard when
go...@leland.stanford.edu | I could be outside riding bike?
------------------------------------------------------------------------------
Harry Phinney
: at which rolling resistance is less than the power generated by
: the rider.
Later in the same posting you write:
: Harry, I'm quite willing to believe that there is some power
: input from the vortices formed behind a moving body.
OK. You're willing to grant that there is some power input from the
vortices behind the fairing. This means that in the very least you
agree that the rider does not have to overcome _all_ of the rolling
resistance. Do you agree or disagree with Tim Smith's assertion that
the available power from the vortices will increase with the square of
the speed? Do you agree or disagree that the power needed to overcome
the rolling resistance increases linearly? If you agree with these two
points, you must agree with Tim's conclusion that there is a critical
speed above which there is surplus power to overcome the rolling
resistance.
Harry Phinney ha...@hp-pcd.cv.hp.com
Thomas H. Kunich
30 mph or more. Go out with your bike to a road that is
dead down wind. Come to a stop and wait to see how fast the
wind will blow you.
I've tried it. I didn't move. Rolling resistance was minimum at this
time, not the rolling resistance of 150 mph. I tried rolling
at 15 mph and coasting. I came to a stop.
I'm sure that you could get considerable power out of a 100 mph
wind or even a 60 mph wind. But how much that is is probably still
pretty small compared to the rolling resistance at 150 mph.
Remember, even though the recirculating flow may have a fairly
large percentage of the external airstream (did the guy say 25%?)
you would still have to couple it to the bicycle and a rider isn't
exactly a perfect drag body.
Harry Phinney
: 30 mph or more.
It'll be a long wait. We simply don't get steady 30 mph winds here. If
the winds are that high they are invariably quite gusty with variable
direction.
: I'm sure that you could get considerable power out of a 100 mph
: wind or even a 60 mph wind. But how much that is is probably still
: pretty small compared to the rolling resistance at 150 mph.
The rolling resistance, in terms of force (e.g. lbf, newtons) is
approximately constant versus speed. It does not increase much
(if any) between 1 mph and 150 mph. Tim Smith corrected my last posting
via email, pointing out that the _force_ (not power) from the wind
increases by the square of the wind speed. This results in a linear
increase in rolling resistance power consumption, and a cubic increase
in the power supplied by the "backflow" wind.
: Remember, even though the recirculating flow may have a fairly
: large percentage of the external airstream (did the guy say 25%?)
: you would still have to couple it to the bicycle and a rider isn't
: exactly a perfect drag body.
Yes, Mark Drela said that a particular body shape showed a backflow
velocity of 25% the freestream velocity. He also said the following:
<Mark Drela's words follow>
If John Howard used this shape for his pace car, he would
have felt a 38 mph tailwind at the "sweet spot". Assuming a drag
area of 3.5 ft^2 (from Bicycling Science), this translates to a
forward push of about 13 lb. This is maybe 5x more than is needed
to overcome the rolling resistance of the small fat tires he used.
You appear to agree with his assertion of a 25% backflow velocity, so
with which part of his analysis do you disagree? Jobst has stated that
small diameter (20") tires on pavement have a rolling resistance force
under 1 pound. While Howard's motorcycle tires on salt surely had
greater resistance, I doubt it was more than 13 times that of bicycle
slicks on pavement. This means that the rolling resistance and backflow
wind combined result in a net _forward_ force on the rider. In the
absence of a braking force (e.g. the rider back pedaling against a
fixed gear), the bike and rider will accelerate.
To look at it another way, if Mark's estimate of a forward force of 13
lb is close, this results in:
(150 miles/hr)(5280 ft/mile)(1/60 hr/min) = 16,200 ft/min
(16,200 ft/min)(13 lb) = 172,000 ft*lb/min = 5.2 hp
So the wind supplies about 5 horsepower to the bike/rider combination.
Conversely, if we (very generously, I believe) assume John cranked out
5 hp, we get a tire/ground force of around 1 pound at 150 mph. That's
enough to overcome the rolling resistance of bicycle slicks on pavement,
but likely not enough to overcome the rolling resistance of his
motorcycle tires on salt.
Harry Phinney ha...@hp-pcd.cv.hp.com
Ralph Smith
>Gregg Mack writes:
>
>> Could the gear ratios have anything to do with this?
> [about no one ever riding 150 mph on rollers]
>
>No! And no one has even gone 100 mph. Now that you mention it, I think
>it would be a great idea to see how fast Howard's bike could be ridden
>on rollers. I suspect, not at all, because the gear is so high that no
>one could get it moving enough to stay up.
>
>jobst_...@hplabs.hp.com
That makes ME wonder ... How did Howard ever get that bike rolling on the
salt flats?
--
Gregg Mack
He used a tether line to the vehicle to get him up to 60 mph at which time he released
it. He was in radio contact with the vehicle driver and used this to help him acceler-
ate at the same rate as the vehicle. BTW, he did use those pedals! ;-)
--
Gregg Mack --------- __o __o __o __o
gm...@oakhill.sps.mot.com ------- _`\<,_ _`\<,_ _`\<,_ _`\<,_
Motorola RISC uProcessors ------ (*)/ (*) (*)/ (*) (*)/ (*) (*)/ (*)
Austin, TX USA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Timothy Smith
>That makes ME wonder ... How did Howard ever get that bike rolling on the
>salt flats?
He had a rope to tow him up to 60 mph. The pedals wouldn't turn
over at slower speeds. At 60 he probably had 40-50 rpm.
Tim Smith