For an overview, see Radial
Momentum and Model
address correspondence to RM FAQ at email@example.com
|Tue, 27 Apr 2004
Brilliant work on radial momentum. One quick question though. On your
overview page, you use the equation:
P = [MR2 / 18 m] / V
However, on the radial momentum page, you derive the equation:
P = 1/3 [MR2 / mV]
Where does the extra 1/6 come from (1/3 * 1/6 = 1/18)?
you for being a careful reader and finding an inconsistency.
My current derivation gives 1/3 and
not 1/18. I am unable to find any derivations on my site that show
Perhaps the 1/6 factor is left over
from some earlier work (the area for one side of the cube is 1/6 the area
of all 6 sides). I also recall seeing the 1/18 factor somewhere in
I do not use the formula in any
other derivations, so I have no other checks and balances on it.
I would be interested in any
insights you might have on this or other topics.
Tue, 20 Apr 2004
... an idea for a dramatic demonstration of the concept. One might install
an air hockey table upside down, hanging from the ceiling (or propped up
from the floor.) Have two players hanging from Gravity Boots hooked on
steel tubes on either end of the table play a game of air hockey upside
down. RM, if I understand the levitation experiment correctly, would seem
to keep the puck well attached to the playing surface, would it not?
active region has a radius of about 1/8 inch for each pinhole, so if the
spacing between holes is, say 1 inch, I'd guess your demo might
can test it by attaching a handle to the top of a puck and
"weighing" it with the air pump on and off.
Tue, 20 Apr 2004
Stunning Photo Of Jet Breaking Sound Barrier
You wrote in the RM FAQ: "I'd like to get a url to such photos."
This has photos, details of how they were made, and videos...
Wilk4: Breaking the Sound Barrier
for the url - see the sound barrier link, above.
Thu, 09 Oct 2003
in Moving Fluids
Hi. I just stumbled onto your site and found it quite interesting. I too
have never quite understood how a "pressure drop" can occur, as
it seems to violate the rules of "relativity" - why should a
mass of fluid moving in a pipe have a different pressure to one that is
stationary? What is special about this movement, from the fluid's point of
view, that causes pressure to change in any way? If you stack a lot of
parallel flows side by side, this lower pressure must still exist, so
effects of the walls can be counted out. Pressure doesn't vary along the
length of the flow if it's related to velocity, so you can completely
enclose this fluid with 6 walls and the pressure in that box must still be
the same. If you stop it, then the pressure rises again?
On the other hand, your description of the Bernoulli Principle is the
first time I have had an understanding of what's going on.
obvious, if you have a 2:1 reduction in the flow (say water), then for
conservation of energy (valid if you can expand and reduce and expand it
again for minimal pressure drop) then the pressure head must reduce by the
kinetic energy added. If the end of the pipe is open, then the pressure
added by the constriction will be that necessary to accelerate the water
jet to the exit velocity (in fact this will always be the case).
I knew that, but
that's a pressure gain not a pressure drop; there's no way you can
"harness" the energy of this so called pressure drop, the only
thing you can do is convert kinetic energy back into potential energy - by
slowing down the flow. Slowing an incompressible flow means radial
expansion. I guess this is what you're getting at (you can probably tell
I'm still working it through as I write it!).
Re plane wings, I thought the "fast flow low pressure" thing had
gone by the wayside years ago.
of it is that flow diverges at the top which lowers pressure - that's why
the wing is tapered (maximum possible lift area) and not a "D"
shape (as well as flow separation, which implies you're not getting
divergent flow) - I've kind of also assumed that the pressure front
generated by the thick leading edge pushes some of the flow that was
destined for the top surface underneath, along with the angle of attack
robbing the column of atmosphere above the wing of pressure by slicing it
off and sending it underneath.
If the Bernoulli
Principle simply relates to the conversion/conservation of energy , then I
assume this will work just as well in the analysis, but the whole concept
of a pressure "drop" is totally meaningless unless there is
convergent or divergent flow.
Now I know how a carburetor venturi works. The motor provides the energy
to accelerate the air, the atmosphere provides the pressure.
Well I knew that, but now I know where the pressure drop comes from and
what it means. If there was no venturi, there would be only asmuch
pressure drop present as is required to get the air moving that fast in
the manifold (obviously), and that pressure drop comes from the
"suck" end causing it to move, not the movement itself.
That's why a paper (or cloth) tube won't collapse, so long as there's a
slight positive pressure feeding one end and it's already flowing, this
provides all the energy needed to the air for it to move as fast as it
does. The air experiences no pressure drop relative to the outside air.
The paper cone collapses because the air wants to keep travelling in a
jet, at the same speed, same pressure, and same diameter. Flow separation
will tend to drag any air that's around this jet away, collapsing the cone
walls. (I say confidently, having just learnt what flow separation
actually is some time last week.)
"Surely" the people who work with this really do understand what
it means, and using the "fast flow low pressure" thing to
explain wing lift is just an attempt to dumb it down for the masses -
catching out many an unaware student along the way. The concepts and maths
are too simple to end up going down different paths, aren't they?
Well, regardless of that, thanks for the explanations on your site and the
opportunity to finally work out for myself another one of those simple but
intriguing questions of basic physics.
A little thinking and some experimentation are very good additions to
memorizing what you find in books, or, for that matter what you find on
Wed, 8 Oct 2003
I just came across your website, and I thought that your theory might be
able to explain a wing phenomenon I've observed over the years.
When flying, I often choose to sit over the wing -- in the seat near the
wing exit, which has more legroom. I regularly see a phenomenon on the
wing which I've never been able to explain: I can see a thin vertical
plane of air coming off the top of the wing, perpendicular to it,
extending the entire length of the wing. This plane seems to be some sort
of refractive effect, as it is somewhat tricky to see, and appears more
clearly when the sun is at the right angle.
The position (front to back) of the plane on the wing is quite dynamic,
moving forward and backward with changes in outside conditions. E.g. when
the airplane is moving very smoothly, the plane is quite stationary; when
the airplane encounters turbulence, the plane shifts -- sometimes
furiously -- back and forth.
The other variable seems to be airspeed. The plane only seems to exist at
high speeds. As the airplane slows for descent, the plane slowly
Have you ever seen this phenomenon? Have you ever heard of it? I'd be
interested in any information you have, or any explanation you might know
of. I look forward to hearing from you.
can see some photos of a similar effect on the sound barrier link, above.
Fri, 25 Jul 2003
Momentum and Potato Chips
First, I am not a trained scientist. This is strictly observation on my
Recently, I stopped at a C-Store and bought gas and a bag of chips. I
proceeded to eat the chips. Not wanting to pollute the roadway, I put the
chip bag on the passenger floor of the vehicle.
I had the driver window rolled down and as I went the highway the empty
chip bag began to hover above the floor of the car. It then proceeded to
gain altitude ( I believe that I was accelerating the car but I was
watching the chip bag and the speedometer).
The interesting part was as far as I could determine with my impromptu
experiment there was not consistent airflow over the surface of the chip
bag that would explain Bernoulli's Principle. In fact the chip bag had
many angles and no established plane uniformity so by my limited
understanding, Bernoulli's Principle could not work, (is that an accurate
Second Bernoulli's Principle requires horizontal motion to function
(correct?). The chip bag hovered with no forward motion. Does Radial
Momentum account for this or I am confusing myself and the theory of
Thanks for any help.
Very Truly Yours,
curvature of your car at the point of your open window induces flow
separation and reduces the presure. You can sometimes feel this
effect on your ears if you open a window while you are driving.
low pressure area likely collects air that enters your car through the
heater port near the passenger floor mat. This flow from the floor
to the window may blow the bag into the air.
Wed, 9 Jul 2003
Air pressure is dependent on volume and temperature as given in the
general gas equation:
P1.V1/T1 = P2.V2/T2
Air molecules are not "paired" - they zip around at random
evidenced by Brownian Motion. ( Atoms may well be paired to form the
molecule- e.g. O2) but they do not break up in air flow. A decrease in
volume will cause an increase in pressure because the same number of
molecules impinge on each other more frequently and probably the force of
repulsion between the molecules increases with decrease in distance
An increase in temperature causes the air molecules to zip around more
rapidly and hence impinge on each other and the container more frequently
causing a pressure rise. At absolute zero the molecules are at rest and
theoretically the pressure might be zero, but all gases liquefy at some
temperature above absolute zero dependent on the pressure and which gas is
If we assume that the temperature change is minimal at low air speeds,
then volume and pressure are interdependent. Considering air flow over an
aircraft wing, the volume can be considered infinite and therefore
pressure is the only likely variable.
If the air
over the top surface has further to go compared with the bottom surface
due to the shape of the wing it may suffer more drag due to the greater
solid surface area.
There is no real
reason why the air should speed up. Intuitively I would think it would be
slowed, because it has further to travel over the wing surface. Air does
not speed up just because it has further to travel - the air molecules
above and below the wing are completely independent of each other.
Your idea that the deflected air also undergoes side spread over the top
of the wing may be correct. On various jet aircraft I see spoilers on the
wing to prevent this happening - probably an admission of imperfect wing
Trust this is helpful.
With kindest regards,
the "longer path" theory somehow assumes that molecules somehow
notice each other at the leading edge of the wing, remember their friends,
and somehow speed up or slow down so they can join up with the same ones
at the end of the trip.
Tue, 8 Jul 2003
I came across this interesting site www.howstuffworks.com
which discusses aerodynamic lift in the engineering section.
good summary of the state-of-the-art thinking on the topic - it concedes
there are problems with the Bernoulli and "longer path" models
Mon, 30 Jun 2003
Is this correct.
The separation point, just behind the crest of the wind has relatively low
pressure and attracts flow from the trailing edge of the wing.
Mon, 30 Jun 2003
I am imagining what is happening as I study the picture of the wing a
tornado and some of your experiments.
Please correct me so I can picture the movement of the molecules in a more
My imagination seems to think that velocity is causing a compression then
expansion as well as a spinning motion on the molecules which causes some
centrifugal forced radial expansion as well as upward spinning on the back
top of the wing.
spinning could also be causing some of the lift on the downward sloping
top left of the wing where the air hits the second time. If the air
movement is left to right or wing movement is right to left.
For some reason centrifugal spinning forced radial expansion and then
contraction seems to be involved when I think about it.
In the Bernoulli pictures I do not see an accounting for the suction or a
vacuum around the back top second half of the wing from the wing
displacing the air.
I am going to attempt sending a quick drawing so you can correct any
misconceptions I may have as a layman.
These are some links that may help explain what I mean.
lift is a function on angle of attack. Wing shape facilitates lift by
entraining the air into laminar flow, rather that turbulent flow.
This saves energy, so the whole operation becomes more efficient, and so
behind the crest in the top on the wing, you can find a point of
separation, that has low pressure, and may actually attract a back-flow
from the rear of the wing.
Thu, 26 Jun 2003
Dear Ed Seykota,
I just wanted to say I read through your cool web-site today. The reason I
found it is because I have had this interesting idea for a
lifting-device for the last 25 years or so which I have been mulling
over in my mind.
And recently I
was thinking about it again and I realized that this stupid Bernoulli
effect might put a damper on its effectiveness.
So I was
thinking about the Bernoulli effect, and I was thinking this Bernoulli
principal is total nonsense (anyway, I hoped so). Anyway I was looking
through all these websites to see if they were right or not. Then I came
upon yours which I initially took to be some screwy guy who goes to a
science demo place and decides he knows better than the people who wrote
But by the time
I finished I was going, god, this guy is bright and I think he is correct.
I am afraid I'm no physicist and couldn't really follow all your
equations, though. Anyway, here is why I don't believe in Bernoulli.
Let's say you
are in a car driving down the highway at 70MPH with your windows closed (I
noticed you have a similar idea on your website called "The moving
jar experiment") and let's say your car is totally airtight.
According to this Bernoulli principal, the air rushing by outside of the
car is now at a lower air pressure than inside the car. My idea for a test
for this is ... well here's one. Measure the air pressure outside
before you start moving. Then bring the barometer into the car and as you
are moving 70MPH, open the windows. If the pressure of the air streaming
by is less, then the air-pressure in the car should immediately drop.
Another way to
do this is, make a small circular hole in the window say on the passenger
side, like about 1 to 2 inches in diameter. Cover it with rubber from a
balloon. If the air pressure outside decreases as you move faster, the
balloon should deflect to show it. I'm afraid I am not interested enough
to actually do this experiment on my car :), but I think it would show
that Bernoulli is bogus.
experiment I thought of. Say you get onto a train and that train then
takes off going at a good clip. Lets say the windows were made of some
flexible material. Then they should bulge out as you are moving, right?
Well, this is basically the same as the last idea. But here's another
angle with the train that I haven't worked out completely so that is shows
the utter absurdity of Bernoulli. If you are on the train, the air outside
is going by at the same speed you are moving, so its pressure according to
Bernoulli is less than the pressure in the train.
Now lets say you
are on the platform watching the train go by. THE AIR IN THE TRAIN IS
MOVING, RIGHT, RELATIVE TO YOU, SO THE AIR PRESSURE IN THE TRAIN IS LESS
THAT THE AMBIENT AIR PRESSURE. Seems kind of contradictory, doesn't it.
The only problem with this is, I can't have a port between the train and
the outside which isn't attached to the train. So the example from within
the train is the only one that makes sense to think about. I mean of
course we know that the air pressure in the train will be the ambient air
It's how it
relates to air moving by that is the question. But lets say theoretically
that we have a stream of air the shape of a train moving by at the speed
of a train. Now the thing is, what is to say that the ambient stationary
air is considered the frame of reference rather than the moving
train-shaped air. As Einstein knew, all physics is relative. To someone
moving along with the train-shaped air, that air is still and the ambient
outside air is moving. So Bernoulli says that air is of lower pressure.
But to someone standing still outside of the train-shaped air, the
train-shaped air is moving and has lower pressure. Well, it can't be both
ways! So doesn't that prove that the idea that moving air has less
pressure than stationary air cannot be valid? The mere fact that either
the moving air or the stationary (or less rapidly moving) air can be
considered the frame of reference. The physics has to work regardless of
which frame of reference you use. In your moving jar experiment, which
I've copied here, you seem like you almost were going in the same
direction as I have above.
The moving jar experiment
Take an empty jar and put the lid on it so as to seal in some air. Now get
in a car and take the jar for a fast ride on the highway. Scientists say
that Bernoulli's Principle predicts that fast moving air has lower
pressure. Do you really think the pressure in the jar changes when you go
Your website mostly seems to say that Bernoulli principal does not explain
flight and floating ping-pong balls etc. But you never seem to say what
I want to say, and that is that the Bernoulli principal is simply wrong!
But I guess you can't say that because under the strict limits you have
set out, incompressible fluid, etc., then it does work. Oh well...
I really like people who try to go up against the wall of what is
generally accepted as truth.
Good luck fighting the establishment!
And good luck getting your Radial Momentum theory published!
ps - it was damn difficult finding your web address, assuming the one I am
sending this to is correct! Otherwise, it was impossible.
do not claim that Bernoulli's Principle is incorrect ... it is simply an
energy balance equation ... I claim that the standard application of the
principle to lift phenomena is incorrect.
is, it's a good tool ... just doesn't fit the problem.
you open a hole in a very flat surface of your vehicle, parallel to the
air flow, you experience no pressure phenomenon.
you open a driver seat window just a crack, up near the point where the
windshield radially deflects the oncoming wind, you can feel the decrease
in pressure in the car.
you build an air scoop and stick it out the window to collect air and
deflect it into the car, you can get an increase in pressure.
Sat, 21 Jun 2003
One more part to my question I just sent you on the tornadoes. I don't
know if you know this or even care but here I go.
Where is the greatest suction on the disk in your experiments ? If the
tube was bigger would the greatest suction be in the middle or a side or
the outer rim of the tube or is the greatest suction somewhere on the disk
away from the tube? Just thinking about tornadoes as air approaches the
I will try a paper disk or possibly a wet cloth to try to figure this out.
minimum pressure between the disks occurs in the "active
region," slightly past the input tube. See
Sat, 21 Jun 2003
This site on Radial Momentum is very interesting. Please excuse me for not
being a Super scientist or Mathematician but I have some questions.
I always hear about how tornados are such a mystery. Could Radial Momentum
be the explanation? Could this be why there are videos of air sucking up
18 wheel trucks hundreds of feet into the air. Is there some kind of
compression and expansion occurring in the upper atmosphere?
I wonder what the cone and disk experiment would look like with smoke and
a digital camera or video camera to capture what is happening? Great! An
excuse for me to get that digital camera I wanted.
Does Radial Momentum and/or The Bernoulli Approach fit into how a hot air
balloon works? Could a combination of your and Bernoulli's theories be the
Maybe a possible Radial Velocity or orbiting of molecules bouncing off
each other as well as Radial momentum could fit in somehow? Maybe the
molecules just bounce off each other haphazardly?
Is there a temperature change occurring in your experiments causing an
increase in the velocity of the molecules or atoms of air? Could the
original cause of velocity in fluid cause or contain friction or
compression of air that causes a temperature change? Does hot air vs. cold
air without momentum or velocity fit in to the theory?
raise some interesting questions. You can observe a cavitation ring
by using water in the levitator.
do not at this time have extensions of Radial Momentum Theory for hot air
balloons or tornadoes.
Sat, 21 Jun 2003
expansion chambers and radial momentum
I had an hour free today so I looked on the net to see if I could find any
useful articles that might help you with your theory validation. I used to
know a fellow who made expansion chambers professionally for racing bikes.
I remember him telling me about a man he knew who worked for Lotus, he
remarked that this man was a genius, which coming from him was a bold
statement considering his intelligence level was very high.
If you want to look into this area and need to talk to a professor type
about how the pressure behaved inside the expansion chamber, I can try and
find out his contact details for you.
refer him to this site.
One thing that stuck in my mind, was that when noise restrictions were
introduced in UK, my friend explained that the method he used for reducing
noise was to "double skin the pipe" meaning it was made of two
pipes with one tightly fitting inside the other.
I could readily understand why the pipe would make less noise, but not why
this reduced the power output by around 5-10%.
The pipes were made from steel sheet approx .030"-.035" thick,
and after looking at your cone collapsing experiment, I think the reason
for the power loss was caused by the secondary skin, restricting the
movement of the inner pipe, because it had created a vacuum between the
Correct me if I am wrong but this seems to indicate that the pipes were
actually expanding and collapsing slightly as the pressure pulses ran
through them? If pressure pulses can deform steel sheet, then surely this
helps to prove your theory on radial momentum.
can observe this phenomenon with a strobe lamp.
When I was deeply involved in this subject, the manufacturers who had the
best expansion chamber designs were Suzuki, Yamaha and Rotax. If you were
to contact them, I am sure you would find someone to help you.
Here's a link to a website that shows a very simple diagram of how these
This site sells software to aid expansion chamber and engine design.
The number of the book I referred to is ISBN 0-85429-329-9
I am assuming that this is related to your work in radial momentum, and
hence maybe of help to you in some way. If it is not please let me know.
comments in red.
cone-shape for exhaust takes advantage of some of the properties of
radial-expansion induction of pressure drop.
the efficiency increase has to do with reclaiming some of the exhaust
energy ... as intake compression for the next stroke. (Just a hunch.)
Sat, 21 Jun 2003
momentum & exhaust pipes
I was reading your experiments on radial momentum and some ideas came to
mind, while looking at your cone experiment that made the cone collapse.
If you were to take a look at the design of the exhaust pipe of a
two stroke racing engine, known as an expansion chamber, you would see it
consists basically of two cones, one expanding away from the exhaust port
and one contracting, the effect of this is to create a PARTIAL VACUUM as
low as 6 psi, which aids the suction of fuel air mixture up from the
crankcase through the transfer ports and into the cylinder.
I am not certain about this, but I think it may add some weight to your
like to see a diagram of the apparatus, with pressure profiles.
Several years ago I was developed a healthy obsession for the tuning of
two stroke engines, and every time I got a new motorbike, I would
immediately begin to take the engine apart and try to “think how the
gases would behave” while flying around inside the air-box, carburetors,
inlet manifolds, reed/disc valves, crankcase, transfer, boost and exhaust
ports and EASILY THE MOST INFLUENTIAL COMPONENT, the expansion chamber.
also also liked to perform such "Gedanken" or thought
Changes in the dimensions of the expansion chamber yield drastic
differences in engine characteristics, such as horsepower, torque, power
band width, maximum rpms.
Reducing the length of the header pipe (the first part of the pipe to
leave the cylinder) would normally cause the engine to
1. Produce more horsepower
2. Make its peak horse power output at approx 1000 rpm higher.
3. Reach peak volumetric efficiency at approx 1000 rpm higher (the point
of maximum torque, and where the engine makes its most beautiful wasp like
noise, also the best rpm to get wheelies)
Increasing the large end diameter of the cones (Therefore increasing its
angle) would increase torque and reduce horsepower. It might be
interesting to see if there is a direct correlation between these types of
forces/powers/energies and the "rate of collapse" of the cones
in your tests. What I mean by this is the ratios between :
1. The wall thickness of the cones
2. The angle of the cones
3 .The psi needed to collapse the cones.
Decreasing the diameter and/or increasing the length of the tailpipe (the
final tube that the exhaust gases leave the expansion chamber from) would
cause the engine to make more power (up to a point) at the expense of
running hotter (constricting the outlet of hot gases, and increasing
If the tailpipe was simply joined at the end of the last cone the noise
level would be very high.
If the same length/ diameter tailpipe was pushed INSIDE the last cone into
its widest point, the power level would remain the same but the noise
would be reduced by approximately 30-50% because the tailpipe end was in a
low pressure area.
Oval-ising of the cones impedes engine performance.
If you would like to read some literature on this subject I can recommend
a book entitled Performance tuning in theory and practice: Two strokes
by Graham A. Bell
Published by Haynes books. Its a very good read and extremely well
explained, as are your experiments. (See chapter 4, The exhaust)
I think you would have already tested this Ed, but if you haven't, it
might be an idea to suspend weights underneath the plastic discs, to see
which pattern of disc can hold the most weight.
have suspended weights and measured inter-plate gaps as one of the ways to
obtain confirming metrics for my model. The experimental results
confirm the theory. See: Model
My guess is that the plain flat one would be the winner, as it has no two
dimensional restrictions to the expansion of radial airflow.
Did you observe that increasing the air or water pressure increased or
decreased the holding force of the discs? I would expect a greater psi
would increase the weight they could hold.
Also I was also curious as the whether or not a slightly convex (such as a
magnifying glass lens) shape or even concave disc would adhere to the
does not work ... acts like a balloon ... no initial creation of radial
flow. Convex is similar to flat, since the active region in very close to
One part of my brain has an inkling that a completely spherical object
like a table tennis ball, would allow 3D expansion of the air/water and
therefore hold the most weight, but another part tells me that it would
not hold in place at all.
ping-pong ball sticks in a funnel.
I am very curious to learn if it does or not.
Another interesting shape to try must surely be a cone, of course testing
It might be an idea to speak to Stephen Hawking about your theory, who I
believe has an IQ of 280 possibly making him the most intelligent person
I wish you luck with your research, and I find it refreshing to see
someone with guts to go up against the so called traditional methods of
doing things, I know what you are up against Ed, as I wrote letters the
Suzuki, Yamaha, Honda, Rotax, Kawasaki, trying to explain the benefits of
my "opposite exhaust port engine" that I designed and built, but
that's another story ...
comments in red.
17 Jun 2003
University Physicist Responds
for your letter.
we have fundamental disagreements; I have seen them before our meeting,
and tried to smooth them. First, let us exclude use of words "radial
expansion". It comprises two things: radial flow, and expansion of
liquid/gas with decrease of density. These are quite different
things actually occur … that is one of my concepts … I am open to
hearing any scientific arguments about the concepts that proceed from
basic physics. Your attempt to restrict language is not really a
you mentioned to me, all conventional scientists thought that the
compressibility of the liquid is not important. The correction
compressibility introduces into velocity profile is proportional to
(v/c)^2 - mathematically speaking. (v is typical speed of the liquid, c is
the sound speed in the liquid). We got the same result - intuitively -
that the correction to the velocity introduced by compressibility is very
small. The velocity is measurable quantity; the correction is small; this
is why nobody cares about that ...
fluid mechanics solutions that derive from Navier Stokes traditionally use
incompressibility to simplify the math. In this case, compressibility is
at the heart of the phenomenon so the simplification is inappropriate.
Your first sentence lacks context and may not apply to the situation at
all. You show no foundation
for your assertion for a velocity profile correction.
You are unable to duplicate my profiles. You are unable to compute
a correction term. You are
posting unnamed peoples’ feeling as a proxy for hard science.
some reason, you want to multiply the correction on bulk modulus. Then, of
course, you will get something of order 1. Why you want to multiply ? I
Modulus (ratio of pressure to change in volume) is the inverse of
compressibility. Your previous argument is that compressibility does not
matter since it is so small. Actually,
for very small compressibility, bulk modulus is very large and explains
the effect. Since I am explaining a pressure change, high bulk modulus
would predict a greater effect, as is true. Incidentally, and consistent
with my theory, the effect is greater for water than for air.
understand it is not easy for you to accept the idea. Unfortunately, this
is the way things are. Forget about me; say I am wrong. Is the correction
do not see you proposing any ideas for me to either accept or
am not saying that the small effect is non-existent. I am just saying
that, being small, it is not very interesting, and this is why nobody
cares (including me; then you also will join). On contrary, the cavitation
is NOT a small effect, and this is why it is interesting.
cavitation effect that I recall predicting and later noticing for water,
is the direct result of radial momentum. So far, I do not see you presenting any alternative
explanations that account for the pressure and velocity profiles -- and
that also have the correct interfaces at fluid entry and exit.
anything could be done about cavitation, we should agree on principles.
Otherwise, it will end not well.
base my argument on science, particularly basic physics.
Your arguments show a lack of connection to any scientific
may think that this tendency to idealization and neglect of small features
of the reality in the favor of clarity and simplicity is just my personal
trait. First of all, this is indeed my trait, and I am happy about
do not say what features you are neglecting.
If you are choosing to ignore compressibility, or bulk modulus, you
are, in effect simply ignoring the central thesis.
this is the very essence of science. The scientist who can do this
idealization and abstraction from non-essential features the best - is the
best scientist (the same in trading). This is not just my personal view, but, rather, I would
think, view of scientific community (though you may argue with that). You
may not like it, but this is the way things are; and I think this is
present no science, essential or otherwise, to which I can respond.
idealization is not easy though since requires understanding, and deep
penetration into subject, and ability to see the essence.
post no evidence of understanding or penetration into the subject matter
– indeed, you do not mention the physics at all, other than in the
context of your feelings.
me I understand how painful is to find that the problem on which you
worked has been done. I know. But - it has been done. Cut the loss. Move
further. Otherwise, you will stretch psychological loss too far.
see no such work. I repeatedly ask you for a solution that explains
the essential velocity, pressure and density profiles, so we may compare
with my solutions. So far you fail to produce such.
I do not feel pain, so much as frustration and disappointment that
a professor of physics would argue a point in physics without citing basic
by the way, I fully appreciate now your words about psychological
compatibility with the trading model, and understanding of personal risk
profile. This part of my personality has not been developed. I'll do a
couple of things with that. I learned a lot from you. Thanks. I indeed
am open to receive any scientific discussion about my theory of Radial
letter on the left is from a physicist who works at a well-known
university ... my comments are in red.
interchange seems typical of others with the academic establishment.
Tue, 20 May 2003
And a physics question: in your levitator, if you remove the ceiling or
lower the air output, so that the air can expand even more freely, do the
plates still levitate?
ceiling is one of the plates, so removing it changes the fundamental
can run the test yourself with a thread spool and a playing card.
Mon, 21 Apr 2003
Just found your
web site on Trading Tribes from the TurtleTrader web site and saw your
response to the FAQ dated April 14, 2003 (subj.: Lift Theory, in the
Physics section) about URLs for the picture of the jet braking the sound
barrier. If you haven't been to the StrangeCosmos www.strangecosmos.com/
web site they have a plethora of pictures (go to the PICTURES section)
from all walks of life. There are a couple military sections. If you go
through the pictures you might find what you're looking for.
Hope this helps you out.
PS - Great story in Market Wizards.
Sat, 19 Apr 2003
I was wondering if you would be so kind and please help me. I was
the web and ran across an article that you had written and it seems to be
closely related to the problem I am trying to figure out. As seen in this
attached, I am trying to predict the pressure drop between two orifices.
One being a fixed size, the other being variable. I have found several
p-drop across a single orifice, but nothing for two.
I know it will
probably take two different formulas because of the flow reaching sonic
velocity. I usually don't email strangers when I can't figure out a
problem, but I can't seem to find
anyone who knows about this subject. Any help at all would be greatly
problem is like trying to blow up a balloon with a hole in it - or trying
to take living expenses out of your trading account.
both cases, the less you withdraw, the better you float. See FAQ
page on www.tradingtribe.com.
Figures 1 and 2 at the bottom of this page. You can simplify your problem
somewhat: assume for 100 psig, that flow is supersonic, and choked. Then
flow is roughly proportional to the product of aperture and pressure drop.
(for subsonic flow, it's proportional to the square root of the pressure
= k * P1 * A1 and
= k * P2 * A2
the flows are equal so
from the problem,
+ P2 = 100 psig
= 100 / (1 + A2/A1)
Figures 1 & 2, below
So for very
large A2 pressure is small, for very small A2
pressure is about 100 psig and for A2 = A1 the
pressure is 50 psig.
Wed, 16 Apr 2003
Thank you for
the quick response.
I did not know,
that the lift is generated mainly near the entry orifice. If so, then
everything looks fine. My curiosity overcame my laziness and I
decided to perform the experiment I described before. It was not perfect,
but I spent half an hour totally absorbed in the project and
I enjoyed it.
I used two
stripes of paper hinged on paper clips between the table and a plexiglass
board parallel to the table.
The most stable
position for the stripes is parallel. No mater what you do with them at
the beginning, they tend to end up parallel If the free-moving ends
are at the same distance as the hinged ones - after blowing air between
the stripes, they remain parallel. If the free-moving ends are at a
greater distance than the hinged ones- the air blown between the stripes
brings them together to parallel.
If the free ends are closer than the hinged ones - the air flow opens them
- to parallel.
If one of the stripes is curved to the outside, making a
"bubbled" channel, the air brings it back, straightens it and
the stripes stay parallel.
I did not try to curve the paper to the inside.
As I mentioned the experiment was not perfect, but I was able to see the
effect of just velocity applied in the situation.
Tue, 15 Apr 2003
I like your radial momentum model.
Although I did not educate myself in physics as much as many others, I
enjoy thinking about different topics and analyzing. Like George Castanza
put it during one of his job interviews , " I enjoy
understanding". I will be happy, if I can contribute anything to the
Seems like radial expansion has something to do with the lift. The most
convincing experiments seem to be the ones with the levitators. The tube
and cone - the tube of a smaller diameter may be stiffer than the cone,
even if made of the same material and thickness -as the radius of the cone
increases, the surface becomes more and more flat, hence easier to fold
The flaw, that I see with the levitators is that the parallel channel
has a smaller surface than the ones allowing for expansion. Whatever
causes the difference in pressure, if is applied to a smaller surface will
result in smaller force.
I have thought of an experiment. It is very simple and probably somebody
has done it before. As you mentioned on your web site, if you blow air
above a stripe of paper, the paper is being lifted. Also if you have two
stripes of paper parallel to each other and blow air in between them,
while holding the ends, the other ends will come closer.
But I do not
know if it is because of velocity or air expansion. Both are happening at
the same time. It would be nice to eliminate one of the factors , to see
if the other has any effect.
We can limit the air flow to the sides ,thus eliminating the expansion, by
two larger planes perpendicular to the surfaces of the paper stripes.
We will then
have a channel with perpendicular walls, two opposite walls made of paper
and two other of stiff material.
The stiff walls
material is transparent, so we can see what is happening. The paper walls
can move at the ends between the stiff walls. The other ends of paper are
being held in place. Even better if we can replace the paper with a stiff
, light , low friction material and fix it on pins going perpendicular to
the stiff, immobile larger planes, so in it is hinged allowing the light
boards to change angle.
The boards will
not flutter like the paper stripes would, but they can still move and
change angles. Now, if we arrange the light boards, that have replaced the
two stripes of paper , parallel and blow air between them, we may see an
interesting effect. I do not know what will happen, but it may be
If the small boards move closer - forget the expansion , they moved
because of velocity. The channel was parallel at the beginning.
If they do not move at all - all is left is radial expansion, velocity has
I cannot foresee them moving apart further than parallel, unless... the
velocity actually increases pressure and the radial expansion
If they move as far as 180 degrees (theoretically, but in practice the
friction would prevent it), then the velocity increases the pressure and
the radial expansion does not compensate.
The last two possibilities are unlikely, in my view,
The main concept here is to have a channel that is parallel at the
beginning and can change the diameter , without changing the resistance
against the implied pressure, like a garden hose or flattened cone would
The whole setup can be tried in different angles , depending on the
desired effect of gravity on the small boards. Maybe laying the large
planes horizontally would be the best.
Also convincing would be making a levitator with a parallel channel of an
identical area as the expanding channels or making the expanding channels
with sharper angles , so they have the same area as the previously built
I am curious if you find my thoughts and ideas interesting or if they can
be of any use. Please, let me know.
Wish you success.
seem to have a good grasp of the theory.
your observation about surface area: see levitator
table. The V plate adheres, although the area between the guides is
about the same as the area between the guides on the parallel plate. The
difference in lift is quite apparent.
V plate lifts and the parallel plate does not.
unrestricted plates with total area much smaller than the parallel area on
the parallel plate show considerable lift.
active lift region is relatively close to the entry orifice.
suggestion for a double strip paper experiment is similar to the long-slit
experiment I ran, in which a business card rests against a smooth
the card sticks to the levitator, it does not stick to the device that
entrains parallel flow.
Mon, 14 Apr 2003
This makes a great deal of intuitive sense if you've ever seen a picture
of the Concorde landing. The curved delta wing of the aircraft generates
twin vortices with the axes of rotation parallel to the
like to get a url to such photos.
ring is analogous to the cavitation ring in the liquid levitator. As the air
expands radially, in a cone extending from the nose of the plane, the
temperature drops and water drops precipitate.