Must be something in your settings. They work for me.

"Simple Simon" wrote in message ...
Movies don't work.


"jlrogers" wrote in message ...
Maybe this will help everybody:

http://www.wb-sails.fi/news/99_4_Win...ies/Movies.htm

"Simple Simon" wrote:
That's precisely why I give more credence to Venturi.

I like to keep it simple as my name suggests. Why
clutter a good physical reality with extra theories
that may or may not be applicable?

In my opinion the theory:
"air tends to follow the sail (also on the leeward),
and thus deflects the air, and for that deflection you need a force,
and that force is the sailforce"

is easier as explaining:
"the path on the leeward is longer, so the air has to move faster"
continued with
"fast moving air has a lower pressure"
"just like in a venturi in a pipe"

Please note that I do not make air molecules bounce of the sail,
I am deflecting a flow of air.
To check if that flow has not separated from the sail I also reccomend
telltales.

Please read www.sailtheory.com/sail.html for more details.

What might be confusing:
Bernoulli never had a theory for a wing. He had a theory for explaining how
high a fountain would spray.
Newton never had a theory for a wing, his theory was about bouncing balls
and planets etc.
Euler, Kutta and Joukofski, and Prandtl all had some theories about flow
around a wing.
For some strange reasons they are not often mentioned.
(I am promoting Ludwigs Prandtl "lifting line theory" if you want to know)

I quit this discussion, I think the "longer path gives higher speed, and
thus lower pressure" theory really sucks.
If you do not need a theory, please do not use a theory. It is better to use
no theory as to use a stupid one.

Thank you for giving your opinion.

Best Regards,
Pim






--
Posted by news://news.nb.nu

If you use GuardIE, Zone Alarm, and Spybot, you can control all of those very well, though I too removed realplayer and used the
minimal install of Quicktime.(Version 6.3 of Quicktime is easy to control). Guardie allows one to activate it by URL. Using Spybot
allows one to reroute defined internet requests to 127.0.0.0. Real just thinks it's calling home.


"Simple Simon" wrote in message ...
I see the problem. The movies are Quicktime. I removed all that horrible
Quicktime crap from my computer. It made it crash everytime I attempted
to use it and it was constantly trying to load ads and other crap from the
Quicktime server. It's almost as bad as RealPlayer which I also removed
every vestige of.


"jlrogers" wrote in message ...
Must be something in your settings. They work for me.

"Simple Simon" wrote in message ...
Movies don't work.


"jlrogers" wrote in message ...
Maybe this will help everybody:

http://www.wb-sails.fi/news/99_4_Win...ies/Movies.htm

"Simple Simon" wrote in message ...
It does depend on the length difference as stated in the principles
of the venturi effect. The speed of the air is increased when it
is forced through a smaller area. The sail acts like one side of
a venturi in that the air has a smaller area to go through because
of the extra length. The air above that air on the surface of the
foil acts like a venturi also to a small degree. The net effect is
the air moves faster, the molecules become spaced farther apart
and the pressure is decreased. This decreased pressure is a greater
factor causing lift than the air pushing up on the windward side of
the sail.

You might know a lot but you need to learn more when it comes
to the practical application of single-surface foils used on sailboats.

Dear Simple Simon!

NASA Glenn Research shows on their website that you are totally wrong
about Lift due to "Longer pathlenght and Half Venturi lift theory"!:

http://www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html

Professor em. of Physics Weltner shows here how misunderstood
Bernoulli equation can be:

http://www.rz.uni-frankfurt.de/~weltner/Mis6/mis6.html

Aerodynamist Martin Ingelman-Sundberg ownsite with articles :

http://www.marv.nu/undersajtm.html

Jan-Olov Newborg

Comments interspersed.

"Jan-Olov Newborg" wrote in message om...
Dear Simple Simon!

NASA Glenn Research shows on their website that you are totally wrong
about Lift due to "Longer pathlenght and Half Venturi lift theory"!:

http://www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html

Not a good example. The simulator uses a symetrical, double-surface
wing and talks of powered flight.

We are talking about a sail which is a single-surface foil here.
Proof that the Venturi effect is what provides the lion's share
of the lift in the system is the fact that the sail is shaped
by the pressures on either side. Because the sail's convex side is
always facing the area of lowest pressure proves the venturi effect
is in action. (This is not true only on a dead run where the shape is
caused by wind action on the windward side of the sail)


Professor em. of Physics Weltner shows here how misunderstood
Bernoulli equation can be:

http://www.rz.uni-frankfurt.de/~weltner/Mis6/mis6.html

The good professor is confusing a descriptive term (longer path)
for a causative agent (lower pressure). The longer path is not the
cause of the lower pressure. The lower pressure is caused by the
speeding up of the air molecules because of the SHAPE of the path.
Use the wrong shape and you will not get lowered pressure. The
shape is the key to lowering the pressure efficiently and without
excess drag - not the longer path.

Because the shape confers a longer path does not mean it is the longer
path that is the cause. The shape of the foil is important not the longer
path. The so-called longer path descriptor is ONLY a descriptor.
This seems to go over the heads of so many professorial types who
are all too involved with nomenclature.


Aerodynamist Martin Ingelman-Sundberg ownsite with articles :

http://www.marv.nu/undersajtm.html

And, this chap is talking only of airplanes and probably has never
sailed in his life and is also unfamiliar with single-sided foils that
are shaped by the wind.

Thanks for the links but I still know I'm right when it comes to
sailboats.

Capt. Neal
http://www.homestead.com/captneal/index.html

~~~~~~~~~~~~~

Donal.

Your reasoning is FLAWED. You are using two different sails, which
cancel out your statement.

However, there is a easier proof that holds true. Use a performance
curve and you will see that your statement may be correct, with the
exception off the wind "Bernoulli" is much more logical.
Off the wind we are getting greater lift from a looser, baggier sail and
the tell-tales streaming back as indicating Bernoulli's description of
flow and recovery area. I know you have seen this while reaching. That
is if you are using leech tell-tales. If not, why not?

Newton's 1st & 3rd laws say the tell-tales shouldn't be streaming to
windward and if Pim Example of the blown paper is correct, the Coanda
Effect should be curling the tell-tales back around the to the windward
side of the sail

Again, If I'm wrong and my eyes are deceiving me, please explain and
give an example.

Ole Thom

I think poor PIM has bowed out of the discussion or at least
that is what he said in another thread. He probablY thought
he could come in here and cherry pick but he quickly found
there are some fine minds at work here. We may carry on
like a bunch of drunks the majority of the time but we know
our sailing!!!


"Thomas Stewart" wrote in message ...
Pim,

Your example of Coanda on the paper, if true, Should wrap the tel-tales
around the sail rather than let them stream back.

I find fault with your reasoning


Ole Thom

Donal.

On your measurement; gain flawed. The measurement should be reflexing
the dymanics of the moving sail. If the sail's measurement of the convex
side thru the air is measured as compared to the distance across the
moving sides of the concave side there would be a great difference. The
faster the movement the greater the delta length

Again I'm open to any example that makes sense

Ole Thom

Forget all the other stuff, this is all you need to know.
Dowra.

U'll remember that next time I Hoover down the lake....
--
katysails
s/v Chanteuse
Kirie Elite 32
Ad eundum quo nemo ante iit.
http://katysails.tripod.com

"Women and cats will do as they please, and men and dogs should relax
and get used to the idea." - Robert A. Heinlein

Hoover? Like the vacuum cleaner?

Katy, I'm shocked that you would admit it.
But, it does make for better fantasies!


"katysails" wrote in message ...

Forget all the other stuff, this is all you need to know.
Dowra.

U'll remember that next time I Hoover down the lake....