Re: [Paddlewise] PaddleWise [wing theory]

Bob wrote:

>As usual, Peter posts a bunch of meaningless* equations when we get to
this subject.  For those of you who might be awed by such, don't be -
Peter understands equations but not physics, and his gobbledy-gook is
not accepted by anybody here with a real clue about physics or fluid
dynamics.

PC: "As usual" ?  what do you know about what I usually do?  Your rude and
personal attack here is entirely unnecessary and unwarranted. I have not
posted in many months.  If you have disagreements, simple state so, there is
no reason for you to resort to personal insults.  Are you so superior in
your knowledge that you can arrogantly boast that you are the only one with
the "real clue" about physics?  What are your qualifications?  On what basis
do you make such an unwarranted and mean spirited personal attack on me?
Your boastful claims are entirely unsupported.  You do not have to accept
what I wrote, but please be civil.  You have not demonstrated that you have
any "real clue about physics or fluid dynamics", only that you are capable
of being rude.

>(* physical meaningless because they don't apply to the physical
conditions he's talking about)

PC:  how do they not apply?  Please explain.  Again you have not supported
your claim. I have many years of applying just such equations to design very
real and very successful designs that actually work in the real world.
Among others, in 1982 I was one of a handful of areodyanicists that spent
many hours doing conceptual and computational fluid mechanics to design the
Northrop B-2 flying wing bomber.  If we did not have a good understanding of
what we were doing the bomber would not be flying.  It flew on the first
flight uneventfully, which would not have happened if just such equations
were not realistic.  So, what are your qualifications?

>I'll just point out for starters this:
\>
>  efficiency=P-out/P-in = TxV/DxV = T/D    since the velocity cancels
>
Note that the velocity cancels because he says it does - because he uses
the same velocity in both places.  But of course the paddle handle does
not move at the same velocity as the paddle blade, so this is complete
nonsense.

PC: If you would carefully read the text, I stated that the thrust IS
directly related to the velocity of the blade, and also the drag on the
blade through the water IS ALSO directly related to the velocity of the
blade through the water.  The faster you pull a blade through the water, the
more drag you feel, and the more thrust you get, and both are directly
proportional to the blade velocity.  They are the same velocity, if you do
not believe me, draw a force vector diagram of a blade and prove it to
yourself.  Besides even if what you claim is true (which is not how I
described it), the handle moves at a velocity prepositional to the blade
velocity, only different by a constant, so the velocity would still cancel
and the relationship is valid.  So how is this nonsense?  Where is that
incorrect?  What would the relationship between the two velocities be and
how does it affect the equation?  Please offer your "correct" equations and
relationships if you think you what they are.

I have clearly stated my assumptions, indicating where there would be
deviations from actual measured results.  And taking in the whole paddler,
paddle, water, hull system, technique, etc. there are too many variable to
accommodate, so one of the hugely simplifying assumptions are that all
things must be equal (which they NEVER are) with the only difference is in
the aspect ratio.  Since this is not a realistic scenario in a comparison of
real paddles, you can take it for what it is worth.  there are other
functions a paddle performs, and for some people the color would be more
important that anything else.  So there is lots of room for legitimate
disagreement about the "real world", I only offered this up since anything I
might say is always questioned with "oh yeah? prove it".  Okay, I did.  So
where is your proof?

Someone posted a question on paddle theory, and I put together the simplest
comparison I could.  You have not responded with anything meaningful or
helpful,  in fact you seem to relish the opportunity to insult and attack my
efforts for some unimaginable reason [and frankly, based on the way you
posted, I think you need quite a bit more than a lesson in fluid mechanics].
if you want to offer an alternative theory to the person making the request,
be my guest.  But please keep your foul diatribe to yourself.

You have not demonstrated that you have read my post carefully enough to
understand this properly.  Besides, these equations are not MY inventions,
they all come directly from the equations published in the books used for
decades by industry experts for fluid mechanics and propeller design.
Please go read those first, and then come back with some meaningful and
hopefully polite discussions.  And you can also write the expert authors in
the books I referenced and tell them they do not know what they are taking
about since you have a clue about real physics, and obviously they do not.
Imagine that, all the experts in the industry have been wrong all these
years, good thing we have people with superior knowledge like yourself to
set us all strait.  When is your first text book on the subject coming out?
I can hardly wait.


Peter C.

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