jon wrote in
ups.com:

On 27 Okt, 17:10, Bertie the Bunyip wrote:
jon wrote
innews:1193496270.442636.260090@d55g2000hs
g.googlegroups.com:





On 26 Okt, 08:24, Bertie the Bunyip wrote:
jon wrote
innews:1193336318.130848.213230@i13g2000pr
f.googlegroups.com:

On 17 Okt, 01:48, Le Chaud Lapin wrote:
On Oct 16, 3:31 pm, Thomas wrote:

On 16 Oct, 19:41, Jim Logajan wrote:

Thomas wrote:
You may want to check out my web pages
http://www.physicsmyths.org.uk/bernoulli.htmand

http://www.physicsmyths.org.uk/drag....oserexaminatio
n of
the physics behind the aerodynamicliftand drag.

You might want to actually _include_Bernoulli'stheorem
somewhere in y
our
pages. You talk
aboutBernoulli'sequation,Bernoulli'sprinciple,
and
Bernoulli'slaw. And yet none of them are actually presented.
Are you
saying they all the same or all different? Why not use the
terminolog
y used
by the professionals and stick with "Bernoulli'stheorem"?
How about including references to relevant texts on your
pages? It's not like s
erious
texts and lab experiments haven't been done on the subject
for a zill
ion
years. It helps to show you know what you're talking about
by showing you've first read the professional literature on
the subject and done
your
own relevant research.

You might also want to redraw your figures so they include
vertical l
abeled
arrows. Then present the assumptions and math needed to
show your wor
k and
why you think the vertical magnitudes sum to zero. Just
saying they d
o, or
they only yield a torque, isn't good enough. It is more
useful to _sh
ow_ -
not pontificate and hand-wave.

P.S. Chapter section 40-3 in volume 2 of Feynman's Lectures
on Physic
s is
as good a place as any to start.

Bernoulli'stheorem is not a fundamental physical law and thus
not
required to understand the principle behind the
aerodynamiclift. And its misinterpretation and misapplication
quite evidently leads to incorrect physical conclusions, like
the claim that a moving gas would inherently have a lower
static pressure than a stationary one. The net flow velocity
of a gas has per se nothing to do with the static pressure.

I so agree. The amout of hand-waving that goes on when
(presumably technically-inclined) individuals invokeBernoulliis
perplexing. Oddly, my college physics book is almost as guilty
- after chapters and chapters of Newtonian mechanics that are
quite clear, they seem to imply just that.

As a thought experiment, consider a large tank containing gas
with a pipe attached to it which leads into a vacuum space.
Assume first this pipe is closed at the end; then the flow
velocity in the pipe is zero because the molecules heading
outwards will be reflected at the end and reverse their
velocity (assume for simplicity that the molecules do not
collide with each other but only with the walls of the pipe
and the tank). If one now opens the pipe, the only thing that
changes is that the molecules heading outwards will not be
reflected anymore at the end but simply carry on heading into
the vacuum space (with the corresponding loss of molecules
being replaced from the large tank). So we now have a net
flow velocity within the pipe without that either the density
nor the speed of the molecules has changed in any way. This
means that the pressure exerted on the inside wall of the
pipe is unchanged despite the fact that we now have a net
flow velocity within it. SoBernoulli'stheorem would quite
evidently give a wrong result here.

Hmmm...technically, someone could argue that, in the vicinity
of the exit hole of the tank, there would be resulting decrease
in pressure, which would be true.

The misapplication, I think, results from too much hand-waving
and not being very specific about what pressure decreases over
what. A venturi apparutus, for example, very clearly
demonstrates a drop in pressure, and that drop is real, but the
points chosen to measure the pressure in the apparutus is very
specific.

-Le Chaud Lapin-- Dölj citerad text -

- Visa citerad text -- Dölj citerad text -

- Visa citerad text -

The venturi pipe is mostly misunderstood. To get through the
narrow section, the fluid must be pressed against the convergent
part with a higher pressure. The Coanda effect forces the fluid
to follow the walls in the divergent part.

All early speed sensors in 1920 used only the divergent part of
the venturi pipe.

Look att Bleriot and other planes. Look at Piper Colt 1953 model
with its backpart venturi. The front convergent part was not
needed.

Piper Colt 1953 model?

Unh unh. First flew in 1960 you fjukkwit.

Backpart Venturi?

Bwawhahwhahwhahwhahwhahwha!

Changing the airflow direction over and under the wing, creates
the local pressure gradients + or - .

Nope.

Bertie

- Dölj citerad text -

- Visa citerad text -- Dölj citerad text -

- Visa citerad text -

The backpart of a venturi is sitting also on the Piper Colt 1960-64
models, like it does on the 1953 TriPacer of the same family.

They didn't make the colt from 60-64, fjukkwit.

One does not need the convergent entrance part, to measure the
airspeed.

One doesn't need a venturi to measure airspeed either, fjukkktard.

OH, BTW, we met real life once. the other pilots in the room nearly
****ed their pants laughing about you in the bar afterwards.

Why don't you tell he bois and gurls here what you do for a living?

Bertie- Dölj citerad text -

- Visa citerad text -

Since you are such a superexpert Bertie, Bombardier needs your help to
fix the landinggear problem!

Now 9 incidents happened with failed landinggear!

So?


We can not block more runways with Q400 anymore and we need your help
Bertie, since you know everything in the

aviation world.


Well, they need to make the gear stronger and more reliable.


happy?



And you still believe the aircrafts are sucked up in the sky, like
Apollo went to the moon?




God I love usenet.


Bertie