Behold: Future Shock

On 07/04/17 06:03, wrote:
On Monday, April 3, 2017 at 6:44:04 PM UTC-7, James wrote:
https://www.specialized.com/us/en/future-shock

-- JS

Look at it this way - what do you do when you approach a bump? Do you
lift your weight off of the handlebars, the saddle or both?

I don't know about you but I lift off of everything but the pedals.
And I prepare my legs to take total weight off of the pedals as much
as possible.

Thinking that taking one step of four is sufficient isn't really good
thinking in my mind.


We have sections of sealed road that are similar to riding a section of
cobbles. The mine field of patches and holes means a bunny hop isn't
going to help. All you can do is hover over the seat, keep your elbows
bent, pedal harder and avoid the really big holes.

This is fine in a straight line for a short distance, but for kilometre
after kilometre it becomes quite wearing. Not to mention the bike tends
to buck around, and if you had to corner it would not be good.

Bigger softer tyres are the go of course. It's not like the roughness
requires the added weight and complexity of suspended wheels.

I've recently moved to extra thick bar tape. It seems to have helped
reduce the buzz in my hands. If my fork crown allowed for more tyre
clearance, I'd put on a fatter front tyre of course. These rough roads
weren't an issue while I lived elsewhere.

--
JS

On Thu, 06 Apr 2017 08:55:04 -0700, Jeff Liebermann
wrote:

On Thu, 06 Apr 2017 09:29:34 +0700, John B.
wrote:

On Wed, 05 Apr 2017 09:52:56 -0700, Jeff Liebermann
wrote:
Yep. For example, some older wheel tractors do not have any springs
or shocks on the big rear wheels. Older models also didn't have them
on the front wheel. The only real springs and shocks were in the
seat.
https://www.quora.com/Why-does-a-tractor-not-have-a-suspension-system
Since the steering wheel was attached to the frame and therefore the
rear wheels, any bump would be directly coupled to the drivers arms.

Do you search out these weird sites or do they simply fall out of the
sky.

Are those the only two choices available? Falling out of the sky
implies divine inspiration, for which I certainly don't qualify.
Looking for weird sites is closer to the mark. Perhaps if I explain
how it's done, you might find my examples worth emulating.

I start with a simple Google word search and quickly switch to an
image search. I don't look for weird sites, but rather look for weird
pictures. When I see a picture that looks "interesting", I click on
"View Image" and then "Visit Site". If the site and associated weird
image corroborate my allegations, I add it to my Usenet posting. If
not, I try again with another weird image. If I don't find anything,
I simply link to the page full of images, which is more for
entertainment value than corroboration.

Having actually (gasp) driven tractors (even at the early age of 12) I
can assure you that the reason tractors don't incorporated suspension
is that they travel so slow that a "bump" is isn't a "bump" at all, it
is simply an irregularity the ground and the tractor climbs up one
side and down the other.

Well, you certainly have more experience with tractor driving than me.
I'm a city slicker but I went to an agricultural college (Cal Poly,
Pomona). At one point, I took a series of agricultural classes in
tractor driving and mechanics that were amazingly applicable to
engineering. I may have held the record for doing the most damage
with a Caterpillar D6 tractor. I also successfully destroyed about
50ft of chain link fence when I was bounced off a Ford 5000 wheel
tractor by one of your non-bumps and the tractor continued on
autopilot. Notice the total lack of any suspension.

To be honest, this sounds like fiction. Or incredible ignorance.

I might add that Yes, I have driven farm tractors and Yes, I have done
considerable work around D-6's, and even 7's and 8's and 9's. When I
worked at the Freeport copper mine in Irian Jaya (as it was then) they
hired stone age savages who had never seen a mechanical device and
within a month they were running D-9's with no problems.

Of course, at the mine there weren't any fences and missing a turn was
probably avoided. As Sam Johnson said "Depend upon it, sir, when a man
knows he is to be hanged in a fortnight, it concentrates his mind
wonderfully", and I suppose the possibility of driving off a 2,000
cliff would have the same effect.

https://www.google.com/search?q=bicycle&tbm=isch
However, I will agree that bumps and lumps have little effect on the
quality of ride on a wheel tractor, which is cushioned by the fat rear
tires.

Actually the large rubber tires are there to improve traction not to
absorb bumps :-)

I would also comment that I have driven a tractor built from a Model T
Ford that had front suspension and it didn't result in the weird
oscillation your cite talks about.

Well, I also don't recall any oscillations, but they certainly can be
created in bicycles. I had one bicycle when I was a juvenile
delinquent that would shimmy violently at one particular speed. I
thought it was normal for bicycles to do that, so I just sped through
the resonance point and rode faster.
https://www.sheldonbrown.com/brandt/shimmy.html

The picture your cite shows to describe how suspension would cause the
tractor to rear up on it's hind legs" (as it were) ignores the point
that the attaching point of the plow is below the rear axle
centerline. Which of course results in a force that tends to rotate
the axle in a direction that forces the body of the tractor toward the
ground.

True. Dragging a plow or other anchor behind the tractor does tend to
stabilize things. Wheel tractors were simply not designed as a
transportation device, but were designed to be dragging something.
Since a wheel tractor has most of its weight over the rear wheels,
there is a tendency for the tractor to lift the front wheels off the
ground when overpowered or one of the rear wheels gets stuck. Dragging
a plow helps.

Even the really, really, old folks knew that.
http://tinyurl.com/mzcyca4

The local steampunk group
http://www.roaringcamp.com
http://kineticsteamworks.org
brings their machines over to Roaring Camp for exhibits. See the
photo of "Pappy". It goes really really really slow. I'll ask them
about the suspension and shimmy issues at the next exhibit.

A Traction Engine, as it was known in England. I've never actually
seen one but my grandfather owned a "gravel pit" and at one time owned
a "Steam Shovel", which (again) I never saw in operation :-)


Actually I doubt very much that
specialized wanted to build a bicycle with a smooth ride. I suggest
that what they actually wanted top do was make a bicycle that they
could convince a lot of people to buy :-)

They said as much on their Future Shock web page:
https://www.specialized.com/us/en/future-shock
See under "Smoother is Faster". However, you're correct that sales is
what drives all such innovation. If it doesn't sell, the money spent
on the innovation is wasted. After smoothness, I presume that
research into which color paint is faster, will follow.

I've always understood that red was the fastest color. Although, come
to think of it, the SR-71's were black.


Your assertion that overloading a truck causes the shock absorbers to
"blow out" seems strange as I've seem a large number of trucks grossly
overloaded that seemed to have no problems.

My 1972 International 1210 3/4ton truck was originally my service
truck when I was in the land mobile radio biz. When the business
collapsed, I ended up with the truck instead of back pay. At the
time, I had switching to engineering and was therefore commuting with
the big truck. The radio sites were on top of mountains serviced by
chronically washed out dirt roads, for which the suspension on the
truck was properly tuned. However, at freeway speeds, the shocks were
too stiff. When it came time to replace the shocks, I installed some
rather light duty shocks to give me a smoother ride on the freeway.
That worked fine, until I had to carry an excessive load, and blew out
all 4 shocks. They were replaced by heavy duty shocks and I installedr
rubber shocks under the bench seat.

Again, this seems, at best illogical. And yes, I've owned, and
presently own. a 3/4 ton pickup. But I never noticed any difference in
driving on rutted dirt roads or smooth freeways that could be
attributed to shock absorbers. Unless, of course, one was driving at
extremely high speeds on the "washed out roads", which seems rather
(well) foolish.

I remember a fleet of
1-1/2 ton trucks that were used to carry cargo from the port of Medan,
North Sumatra to villages north of the city that were so overloaded
that they bolted wooden blocks to the frames to prevent the truck bed
from resting on the tires.

We did much the same with a flat bed truck that we built from junk
parts. It had an excessively wide axle that put the wheel well
directly over the middle of the tires. So, we did some more body
work, gouged out the wheel wells, and extended the wheel wells with
plastic racing imitations. The front wheels never did track correctly
on turns, but that wasn't an issue because the truck never left the
yard.

I'm not sure what you are saying here. The Indonesian trucks were
quite obviously purchased with only the cab and the cargo bed was
locally built with steel cross members and a plank cargo bed bolted on
top. No "wheel wells". In fact this seems to be the norm here too.

--
Cheers,

John B.

On Fri, 7 Apr 2017 08:22:53 +1000, James
wrote:

On 06/04/17 02:52, Jeff Liebermann wrote:
On Wed, 05 Apr 2017 13:23:05 +0700, John B.
wrote:

On Tue, 04 Apr 2017 18:46:24 -0700, Jeff Liebermann
wrote:
Not really. When riding your bicycle, you have 5 points of contact
with the machine. Two arms on the handlebars, two feet on the pedals,
and one posterior on the saddle. If you do anything to take the load
off one or more of these, the load is simply transferred to the
others. If a sprung handlebar were to apply an upward force on the
hands for an extended period of time, the lost upward force would
redistribute itself in additional force on the saddle and feet. You
might get some temporary relief from gravity in the arms from a sprung
handlebar, but when you return to earth from the initial launching,
your arms will feel both the upward return force plus the original
weight of supporting your upper body. That's what you feel when you
jump and land. Sorry, no free lunch today.

I see. You are telling me that the rather elaborate springs and shock
absorbers under my wife's car are a waste of money? After all there
are always just those four tires carrying all the weight?

Yep. For example, some older wheel tractors do not have any springs
or shocks on the big rear wheels. Older models also didn't have them
on the front wheel. The only real springs and shocks were in the
seat.
https://www.quora.com/Why-does-a-tractor-not-have-a-suspension-system
Since the steering wheel was attached to the frame and therefore the
rear wheels, any bump would be directly coupled to the drivers arms.


I thought that was standard practise for tractors. My Kubota tractor is
certainly like that, as is my ride on mower!

Even with horses the attaching point is below the center of gravity
(as one might call it).
https://en.wikipedia.org/wiki/File:Sledge_2.JPG
--
Cheers,

John B.

On Fri, 07 Apr 2017 08:59:16 +0700, John B.
wrote:

To be honest, this sounds like fiction. Or incredible ignorance.

Inexperience, going too fast, not watching where I was going, debris
on the field, and twisting one ankle so that I couldn't run after the
tractor. Unfortunately, that was about 1967, before digital cameras
became common, so I didn't take any photos. I might find one of me
with crutches. It's also difficult for me to remember incidents from
50 years ago, but if there's something specific that seems lacking,
I'll try to recall the details.

Incidentally, notice the throttle on the Ford 5000 tractor:
http://www.tractordata.com/photos/F000/266/266-td4-b02.jpg
It's the lever to the right of the steering wheel. Let go of the
throttle lever and it just keeps going and going and going.

Here's a rear view of the tractor:
https://www.tractorpartsasap.net/eqphotos/EQ-18052-D.jpg
No suspension. I bounced over the low back of the seat, bounced off
the left fender, and came down on an auxiliary hydraulic pump that was
attached to the PTO (power takeoff). The hydraulic lift cylinders in
the photos were not present. Looks like the seat was replaced in this
photo:
http://en.visonerv.com/cgi-bin/md/M11646/s3.pl

I might add that Yes, I have driven farm tractors and Yes, I have done
considerable work around D-6's, and even 7's and 8's and 9's. When I
worked at the Freeport copper mine in Irian Jaya (as it was then) they
hired stone age savages who had never seen a mechanical device and
within a month they were running D-9's with no problems.

As I previously mentioned, the few classes I took in tractor driving
and mechanics at Cal Poly were the sum total of my experience with
tractors. Add in a little dirty work over the years with a backhoe
and small skip loader, but those don't really count.

At Cal Poly, we had our own equivalent of stone age savages. They
were foreign exchange students, mostly from Iran (before Shah Pahlavi
was deposed). Being the sons of Iran's elite, they were not expected
to do any manual labor or tasks that were deemed to be menial. A few
brought their servants with them to do these things. Few had every
operated a screwdriver, much less a complicated machine. Teaching
them basic mechanical skills was challenging but most survived.
Looking back, I think we could have done better with your stone age
savages.

Of course, at the mine there weren't any fences and missing a turn was
probably avoided. As Sam Johnson said "Depend upon it, sir, when a man
knows he is to be hanged in a fortnight, it concentrates his mind
wonderfully", and I suppose the possibility of driving off a 2,000
cliff would have the same effect.

We had the equivalent of the 2,000 ft cliff available. It was the
nearby San Bernardino Freeway (I-10). One wrong turn from the
practice field and the tractor would be climbing a short onramp into
traffic. The school probably deduced that nobody would be dumb enough
to try driving a tractor on the freeway, and therefore did provide any
protective measures. Well, someone did try, survived, and was the
inspiration for the chain link fence that I partially mangled.

Actually the large rubber tires are there to improve traction not to
absorb bumps :-)

True. The tire pressure varied depending on what we were doing with
the tractor. Quite a bit of classroom time was spent to the topic. As
I vaguely recall, we used 17 psi on a wheel tractor with zero load on
the hitch. I could see the tire bounce a little from the weight of
the tractor, but nothing that would be considered a shock absorber.

A Traction Engine, as it was known in England. I've never actually
seen one but my grandfather owned a "gravel pit" and at one time owned
a "Steam Shovel", which (again) I never saw in operation :-)

I've had a little experience with steam engines. Mostly dirty work in
trade for getting free rides and helping a college friend build a
working steam car.

After smoothness, I presume that
research into which color paint is faster, will follow.

I've always understood that red was the fastest color. Although, come
to think of it, the SR-71's were black.

There's been quite a bit of work on optimizing aerodynamic surfaces on
anything that is expected to move rapidly. In theory, the ideal
aerodynamic surface would look like a golf ball.
https://www.google.com/search?q=mythbusters+golf+ball+car&tbm=isch
The idea is to maintain laminar (non-turbulent) flow over the largest
surface area. Color plays a small part by heating the air near the
surface. Hot air is less dense than cold air, so hot air means
slightly less air friction and wind resistance. The black SR-71 color
was no accident where at Mach 3, little things like surface heating
become important. The ideal bicycle frame would be dimpled and black.
I'm sure Specialized has considered the possibilities, and immediately
discarded them as unsellable.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Thu, 6 Apr 2017 13:40:46 -0700 (PDT), Doug Landau
wrote:
Thanks all! I would like to add that before asking, I did google.
Here is what I found: https://www.google.com/patents/US20060051227
Unfortunately reading that felt like a setback. Could someone please
interpret that page for me?

No. I can't understand anything in the patent or what it has to do
with bicycle tires.

Rewind. The original article sorta, kinda, maybe, explained it:
https://www.specialized.com/us/en/future-shock

Not All Compliance is Created Equal

When it comes to compliance, there are two competing schools
of thought. In one corner, there's splay. In the other,
there's axial compliance. Essentially, splay is the fore
& aft movement of the front axle, relative to the frame,
as a result of any bending of the frame and fork. Meanwhile,
axial (or vertical compliance) can be characterized as the
movement of the handlebars, relative to the front axle, as
a result of fork, frame, and stem compliance.

We tested both along all of the critical performance metrics,
and what we found is that, while splay certainly excels
in the comfort department, it's neither the smoothest or
fastest. Vertical compliance, however, was off the charts
in relation to all of the aforementioned criteria, and thus,
we had a runway to create a revolution in compliance: The
all-new Future Shock.

Reading between the lines of marketing gibberish, it would seem that
compliance has something to do with the bending of the frame and fork.
Decoding the buzzwords, my non-authoritative guess(tm) is that:
1. Radial compliance is the opposite of splay, which is the change in
wheelbase length caused by the bending of the front forks.
2. Axial compliance is the opposite of the change in distance between
the handlebars and the front axle caused by bending in the fork,
frame, and stem.

Note that I'm assuming that "compliance" is the same as "stiffness"
which is the opposite of "bending". The mention of "revolution in
compliance" seems to really mean "more stiffness".

Duz this help?


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Fri, 07 Apr 2017 09:37:15 -0700, Jeff Liebermann
wrote:

On Fri, 07 Apr 2017 08:59:16 +0700, John B.
wrote:

To be honest, this sounds like fiction. Or incredible ignorance.

Inexperience, going too fast, not watching where I was going, debris
on the field, and twisting one ankle so that I couldn't run after the
tractor. Unfortunately, that was about 1967, before digital cameras
became common, so I didn't take any photos. I might find one of me
with crutches. It's also difficult for me to remember incidents from
50 years ago, but if there's something specific that seems lacking,
I'll try to recall the details.

Incidentally, notice the throttle on the Ford 5000 tractor:
http://www.tractordata.com/photos/F000/266/266-td4-b02.jpg
It's the lever to the right of the steering wheel. Let go of the
throttle lever and it just keeps going and going and going.

Hand throttles were/are pretty common on tractors. But I never saw one
that required the operator to maintain a death grip on it. Just
pull/push to get the right RPM and you could work all day without
touching it again.


Here's a rear view of the tractor:
https://www.tractorpartsasap.net/eqphotos/EQ-18052-D.jpg
No suspension. I bounced over the low back of the seat, bounced off
the left fender, and came down on an auxiliary hydraulic pump that was
attached to the PTO (power takeoff). The hydraulic lift cylinders in
the photos were not present. Looks like the seat was replaced in this
photo:
http://en.visonerv.com/cgi-bin/md/M11646/s3.pl



At Cal Poly, we had our own equivalent of stone age savages. They
were foreign exchange students, mostly from Iran (before Shah Pahlavi
was deposed). Being the sons of Iran's elite, they were not expected
to do any manual labor or tasks that were deemed to be menial. A few
brought their servants with them to do these things. Few had every
operated a screwdriver, much less a complicated machine. Teaching
them basic mechanical skills was challenging but most survived.
Looking back, I think we could have done better with your stone age
savages.

Of course. After all a "gentleman" cannot be expected to actually
perform physical labour. Can he? Labour is preformed by them. Not US!
This is noticeable in many societies. The Irians I mentioned were all
"po folks". The Upper Class had large numbers of pigs and a sufficient
number of wives to care for them :-)

In fact, the mine caused an upheaval in the local societies that were
effectively pre stone age as I never saw any of them with a stone or
metal tool.

The mine paid in cash but of course cash has no value in the mountains
of Irian Jaya so there was a "company store" where one could exchange
one's cash for material goods like Levi's and steel knives and axes.
Can you imagine being the only one in a village with a steel axe? More
better than a Cadillac Car!


A Traction Engine, as it was known in England. I've never actually
seen one but my grandfather owned a "gravel pit" and at one time owned
a "Steam Shovel", which (again) I never saw in operation :-)

I've had a little experience with steam engines. Mostly dirty work in
trade for getting free rides and helping a college friend build a
working steam car.

After smoothness, I presume that
research into which color paint is faster, will follow.

I've always understood that red was the fastest color. Although, come
to think of it, the SR-71's were black.

There's been quite a bit of work on optimizing aerodynamic surfaces on
anything that is expected to move rapidly. In theory, the ideal
aerodynamic surface would look like a golf ball.
https://www.google.com/search?q=mythbusters+golf+ball+car&tbm=isch
The idea is to maintain laminar (non-turbulent) flow over the largest
surface area. Color plays a small part by heating the air near the
surface. Hot air is less dense than cold air, so hot air means
slightly less air friction and wind resistance. The black SR-71 color
was no accident where at Mach 3, little things like surface heating
become important. The ideal bicycle frame would be dimpled and black.
I'm sure Specialized has considered the possibilities, and immediately
discarded them as unsellable.

Actually the dimples in a golf ball aren't the whole story. Years ago,
when I played golf, I came across an article in a British golfing
magazine about a bloke who had done considerable experimenting with
golf balls. The dimpled balls have to spin to increase the range. He
had concocted a muzzle loading mortar to launch balls with and without
spin and proved that a ball without spin wouldn't fly far. Something,
I'm sure, that the golf ball manufacturers already knew :-)

By the way, the SR's leaked fuel when on the ground. Not a downpour
but a sort of drip, drip. We did a little work on them when I was in
SAC prior to them being fully manned and according to their people
once they got up to speed, or operating temperature one might say,
they expanded and stopped leaking.
--
Cheers,

John B.

On Sat, 08 Apr 2017 08:18:23 +0700, John B.
wrote:

Of course. After all a "gentleman" cannot be expected to actually
perform physical labour.

It was a bit more complexicated than that. The exchange students were
all sons of VIP's, government ministers, and the wealthy upper class.
In the middle east, they were not expected to do any real work.
However, their fathers seemed to consider this a bad thing, which is
one reason they were sent to the US to get an education. To prevent
the students from doing much besides studying, the fathers would
drastically restrict the how much spending money they sent their sons.
While they appeared obviously well off, they were also chronically
short on cash. At the time, I was the local loan shark, loaning money
exclusively to these students. That worked very well as they knew
that they might get sent home if the fathers ever found out.

Can he? Labour is preformed by them. Not US!
This is noticeable in many societies. The Irians I mentioned were all
"po folks". The Upper Class had large numbers of pigs and a sufficient
number of wives to care for them :-)

Different societies have different ideas of what constitutes wealth.
In the US, wealth is marked by the number of coulombs of charge, saved
in a rather volatile computer storage system, that represents the
quantity of government paper that a person has accumulated. Pigs and
wives would seem like a better and more reliable alternative.

In fact, the mine caused an upheaval in the local societies that were
effectively pre stone age as I never saw any of them with a stone or
metal tool.

One of my former friends (never loan a friend money) has a problem
that might also appear in your pre-stone age workers. His father was
an automobile mechanic and didn't want his son to grow up also being a
mechanic. Every time his son tried to use a tool, his father would
take it away. Predictably, his son grew up with absolutely no
mechanical abilities and literally could not operate a screwdriver or
hammer. I had always thought such skills were instinctive or easily
learned, but apparently not. Did something similar happen with the
pre-stone age workers when they tried to use metal tools?

Actually the dimples in a golf ball aren't the whole story. Years ago,
when I played golf, I came across an article in a British golfing
magazine about a bloke who had done considerable experimenting with
golf balls. The dimpled balls have to spin to increase the range. He
had concocted a muzzle loading mortar to launch balls with and without
spin and proved that a ball without spin wouldn't fly far. Something,
I'm sure, that the golf ball manufacturers already knew :-)

Yep. It would seem that the laminar flow would improve as the golf
ball velocity increased. With rotation, it would also provide a more
even distribution of air flow near the surface and eliminate stagnant
air at the leading and trailing ends of the ball. I'm guessing, but
spin does seem to be a good idea. Unfortunately, a spinning bicycle
frame might be a little impractical.

By the way, the SR's leaked fuel when on the ground. Not a downpour
but a sort of drip, drip. We did a little work on them when I was in
SAC prior to them being fully manned and according to their people
once they got up to speed, or operating temperature one might say,
they expanded and stopped leaking.

http://www.historyinorbit.com/15-fascinating-facts-about-the-sr-71-blackbird-the-fastest-plane-on-earth/10/
So it is written, so it must be.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Saturday, April 8, 2017 at 12:40:19 PM UTC-4, Jeff Liebermann wrote:
Snippeed
http://www.historyinorbit.com/15-fascinating-facts-about-the-sr-71-blackbird-the-fastest-plane-on-earth/10/
So it is written, so it must be.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Shouldn't that be the fastest manned plane above the earth? LOL VBEG

Cheers

On 4/8/2017 12:40 PM, Jeff Liebermann wrote:
On Sat, 08 Apr 2017 08:18:23 +0700, John B.
wrote:

In fact, the mine caused an upheaval in the local societies that were
effectively pre stone age as I never saw any of them with a stone or
metal tool.

One of my former friends (never loan a friend money) has a problem
that might also appear in your pre-stone age workers. His father was
an automobile mechanic and didn't want his son to grow up also being a
mechanic. Every time his son tried to use a tool, his father would
take it away. Predictably, his son grew up with absolutely no
mechanical abilities and literally could not operate a screwdriver or
hammer. I had always thought such skills were instinctive or easily
learned, but apparently not. Did something similar happen with the
pre-stone age workers when they tried to use metal tools?

I think there's a lot of individual variation. My favorite photo of my
grandson was taken when he was, oh, maybe 1 year old. IIRC it was an
age where he could walk, but not yet talk. Anyway, his non-mechanical
dad and I were working on something outside. The little guy walked over
to the open tool box, took out a Phillips screwdriver, toddled over to a
bike that was parked nearby, and plugged the screwdriver into a Phillips
screw on the fork blade and tried to turn it.

And for a while, his favorite toy was a power screwdriver. His mom
mentioned taking a shower while he was in the bedroom, coming out of the
shower and finding one of the bathroom door hinges had been partly removed.


Actually the dimples in a golf ball aren't the whole story. Years ago,
when I played golf, I came across an article in a British golfing
magazine about a bloke who had done considerable experimenting with
golf balls. The dimpled balls have to spin to increase the range. He
had concocted a muzzle loading mortar to launch balls with and without
spin and proved that a ball without spin wouldn't fly far. Something,
I'm sure, that the golf ball manufacturers already knew :-)

Supposedly the purpose of the dimples is to add energy to the boundary
layer, which allows it to stay attached further around the perimeter of
the ball. IOW they delay flow separation. The detached low pressure
area behind the ball is thus smaller, so aero drag is less.

This works with other objects as well, independent of spin. Some
airplane wings and some race car bodies have little "vortex generators"
installed for the same purpose.

Yep. It would seem that the laminar flow would improve as the golf
ball velocity increased. With rotation, it would also provide a more
even distribution of air flow near the surface and eliminate stagnant
air at the leading and trailing ends of the ball. I'm guessing, but
spin does seem to be a good idea. Unfortunately, a spinning bicycle
frame might be a little impractical.

I suspect that the big effect of spin is to increase lift, keeping the
golf ball in the air longer. Backspin has a lifting effect by slightly
speeding relative air velocity over the top, slightly reducing air
velocity on the bottom. As Bernoulli predicts, the result is a net
upward pressure. This action is obvious when (for example) playing
table tennis.


--
- Frank Krygowski