How Aircraft Stay In The Air

"Sarah Hotdesking" wrote in message ...
I received this today:-

There are still people in this company who think we weigh aircraft to find
out how much they weigh, not to calculate stresses. Of course we need to
know how much the thing weighs. How are we ever going to know how many
Thrust Pixies we need to get the thing off the ground if we don't know the
weight? Or should that be "Lift Demons"? Pixies have largely fallen into
disrepute - something about Bernoulli not being representative in unbounded
conditions and cause and effect being transposed in the Newtonian model.

In fact the use of Lift Demons on civil aircraft programmes is generally not
that good an idea. The Demon binding contract tends to specify payment in
blood or souls. This is readily achievable with aircraft of military
function, but frowned upon in civilian circles as they may attempt to
acquire payment outside of the terms of their binding contract. Lift Demons
are not used on Elf bombers. We don't talk about Lift Pixies too often as it
seems to upset the self-loading cargo.

Pixies require payment in cakes, flowers or nice thoughts. These are readily
sourced either from the in-flight catering, or provided cost-free by the
passengers. Clearly this would not work well within an operational military
environment. Air force cooking is not renowned for the "light and fluffy
texture" that Thrust Pixies demand, the availability of flowers might be
problematic in desert operations, and nice thoughts may also be hard to find
during times of active operations.

There is also a scalability issue. While one rampant Lift Demon would have
few problems supporting a fighter aircraft (particularly if there is an
immediate prospect of blood), it'll struggle to achieve level controlled
flight of a 560tonne Airbus A380. Use of more than one Lift Demon on the
same flight vehicle is contra-indicated (they squabble and eat each other).
Communities of Thrust Pixies can be encouraged to work together on the same
aircraft by the provision of advanced technologies such as Lemon fondant
icing, variegated tulips or in-flight romantic comedies.

Ryanair once requested Leprachauns be installed in place of Lift Pixies, but
leprechauns have a mission statement which indicates their desire for
monetary gain, and their willingness to search all over the world for it.
This makes Lift Leprechauns expensive to keep (gold vs lemon fondant icing),
and makes it difficult to establish a regular route network as the Lift
Leprechauns don't like to continuously visit the same locations. By law,
aircraft also have to have a full complement of In-Flight Gremlins, but
these are generally not a problem unless you feed the Wingtip Vortex Faeries
after midnight.

A better link to new Non Lift Demon Article:

http://www.iop.org/EJ/abstract/0031-9120/38/6/001/


Jan-Olov Newborg

Gernot Hassenpflug wrote in message ...
(Jack Linthicum) writes:

For those lucky enough to find theselves in Tokyo and in need of a
real spicy food fix may I recommend the Restaurant Ajanta? Try the dry
minced curry (Called Chicken Korma in the rest of the world) and be
very careful if you are offered what appears to be an innocent
marinated vegetable salad. http://www.ajanta.co.jp/index-e.html They
used to be in a little hole-in-the wall near the Indian Embassy but
from their ad now seem to have gone high-rise.

Aha, wonderful! Thanks for that. Are you in Japan occasionally then?
Let me know...

Not recently, I got the recipe for Dry Mince Curry from Mr. Murti the
Younger. Mr. Murti Senior used to pull the free salad routine on those
who thought they could handle hot foods. Unfortunately beer doesn't
help, although a liter bottle can make you feel like it doesn't
matter.

I have it on fair authority that current research in the field of
inertia
free propulsion has shown great promise through the use of properly
modified felines.

There seem to be some modified felines at www.messybeast.com/winged-cats.htm
and even some reports of flightworthiness!

There was some research into the theory of falling toast, and it was
discovered that the toast did not always land with the buttered side
down. Further investigation showed that this was because the wrong side
had been buttered.

I don't have the URL for this, unfortunately, so does anyone know what
methods are used to ensure that the correct side is buttered?
--
Peter

Ying tong iddle-i po!

There was some research into the theory of falling toast, and it was
discovered that the toast did not always land with the buttered side
down. Further investigation showed that this was because the wrong side
had been buttered.

Then you know also of the experiment of fastening a piece of buttered toast
(which always lands buttered-side-down) to the back of a cat (which always
lands feet-down). Drop the combination from a reasonable height and it will
hover in mid-air while the paradox is being resolved.
--
Bruce B. Reynolds, Trailing Edge Technologies, Glenside PA

Peter Twydell wrote in message ...
There was some research into the theory of falling toast, and it was
discovered that the toast did not always land with the buttered side
down. Further investigation showed that this was because the wrong side
had been buttered.

I don't have the URL for this, unfortunately, so does anyone know what
methods are used to ensure that the correct side is buttered?

That is an easy one. The side on the plate that is downward is NOT the
to be buttered side.
To create a machine of great simplicity just butter BOTH sides and
drop the slice of toast toward the floor.
:-)

Sarah Hotdesking wrote:


Probability of carpet impact is determined by the following simple
formula:

p = s * t(t)/t?



'p' is the probability of carpet impact,

's' is the "stain" value of the toast-covering substance - an
indicator of the effectiveness of the toast topping in permanently
staining the carpet. Chicken Tikka Masala, for example, has a very
high s value, while the s value of water is zero.

t? and t(t) indicate the tone of the carpet and topping - the value of
p being strongly related to the relationship between the colour of the
carpet and topping, as even Chicken Tikka Masala won't cause a
permanent and obvious stain if the carpet is the same colour.

I think you missed the important factor 'v' in the above equation. 'v'
is the value of the carpet.

Syiad
--
Live every life as if it were your last.

On Fri, 27 Feb 2004 20:09:29 GMT, Mike Lechnar
wrote:

How did this secret information make it into the public domain? I've
been a practicing Aircraft Performance Engineer for the past 26 years
and have always tried to explain how airplanes fly by using the official
public explanations regarding Bernoulli, airfoils and other such rot.
Civilians just weren't ready for the truth. In fact, we generally don't
speak about the magic directly. Most of our plans and estimates usually
end with the phrase "and then a miracle happens".

I let the cat out of the bag over a decade ago.

Here, in a sci.aeronautics posting from 1994, is the explanation of
lift demons. It has since been elaborated a bit.

Subject: Lift demons

Mary Shafer ) explains lift:

OK, here it is--the real, intuitively-obvious-even-to-the-lay-person
explanation of lift.

People, lift is caused by lift demons. These little, invisible demons
hold on to the leading and trailing edges of the aircraft and lift it
into the air by flapping their wings (so, in a reductionist sense,
lift is actually caused by feathers). Some of the demons are a little
confused and they hold on backwards, causing drag.

The reason that planes stall at high alpha is that the leading edge
demons get scared and let go when they can't see the ground anymore.

Lift demons have good taste and don't like to look at ugly aircraft,
so they hold on backwards on ugly planes. That's why gliders have
so much lift and so little drag and why F-4s have lots of drag.

John Wolter ) asked:

What I would like is a simple *intuitive* explanation of what
causes lift
on a lift demon's wing. (Here we go again... ;-)

Mary Shafer ) replied:

Feathers. The multiple filaments on feathers trap the air molecules
and they struggle to escape, which causes the action-reaction that we
call lift. Bat wings don't have feathers but they're hairy and that
works just about as well (air molecules are a little claustrophobic).

And Richard Winterstein ) suggested another
mechanism:

It was originally believed smaller lift demons, who had their lift
produced by even smaller lift demons, etc., as proposed by the great
Greek philosopher/scientist Miasma. However, with the revival of
scientific knowledge that eventually ended the Dark Ages, it was
realized that this situation was unresolvable according to Zeno's
paradox.

Of course, the 'infinite demons' theory works in many problems of
engineering significance, but a real understanding requires that the
ether be introduced into the analysis at some point. The ether
concept, of course, explains why planes fly more efficiently at higher
altitudes, and, of course, is an absolute necessity when studying
orbital and interplanetary travel, where (it is believed) many of the
lift demons are unable to breathe. Hope that settles the question.

And in a follow-up:

Do shock waves act like cattle prods and make the lift deamons
try to escape? Is why supersonic aircraft are so fast and so
noisy. Why do blimps work? -D

[Moderator's note: Blimps work because the lift demons can cling to
the seams in the envelope and the wires for the advertising lights, of
course. And there are specialized supersonic lift demons (they hang
around Harley-Davidsons when there's nothing flying) that are a little
noisy. Transonic drag rise/lift reduction is caused by the subsonic
lift demons handing off to the supersonic lift demons, since there are
only so many places for the demon to grab on. I'd never thought about
the shock waves--any ideas out there? MFS]
--
Mary Shafer Retired aerospace research engineer

actually, it is a very simple answer,
Money
the more you throw at a plane, the faster/higher it goes.

Matt Gunsch,
A&P,IA,Private Pilot
Riding member of the
2003 world champion drill team
Arizona Precision Motorcycle Drill Team
GWRRA,NRA,GOA

On Sun, 14 Mar 2004 21:38:31 -0800, Mary Shafer wrote:

On Fri, 27 Feb 2004 20:09:29 GMT, Mike Lechnar
wrote:

How did this secret information make it into the public domain? I've
been a practicing Aircraft Performance Engineer for the past 26 years
and have always tried to explain how airplanes fly by using the official
public explanations regarding Bernoulli, airfoils and other such rot.
Civilians just weren't ready for the truth. In fact, we generally don't
speak about the magic directly. Most of our plans and estimates usually
end with the phrase "and then a miracle happens".

I let the cat out of the bag over a decade ago.

Here, in a sci.aeronautics posting from 1994, is the explanation of
lift demons. It has since been elaborated a bit.

Subject: Lift demons

Mary Shafer ) explains lift:

OK, here it is--the real, intuitively-obvious-even-to-the-lay-person
explanation of lift.

People, lift is caused by lift demons. These little, invisible demons
hold on to the leading and trailing edges of the aircraft and lift it
into the air by flapping their wings (so, in a reductionist sense,
lift is actually caused by feathers). Some of the demons are a little
confused and they hold on backwards, causing drag.

The reason that planes stall at high alpha is that the leading edge
demons get scared and let go when they can't see the ground anymore.

Lift demons have good taste and don't like to look at ugly aircraft,
so they hold on backwards on ugly planes. That's why gliders have
so much lift and so little drag and why F-4s have lots of drag.

John Wolter ) asked:

What I would like is a simple *intuitive* explanation of what
causes lift
on a lift demon's wing. (Here we go again... ;-)

Mary Shafer ) replied:

Feathers. The multiple filaments on feathers trap the air molecules
and they struggle to escape, which causes the action-reaction that we
call lift. Bat wings don't have feathers but they're hairy and that
works just about as well (air molecules are a little claustrophobic).

And Richard Winterstein ) suggested another
mechanism:

It was originally believed smaller lift demons, who had their lift
produced by even smaller lift demons, etc., as proposed by the great
Greek philosopher/scientist Miasma. However, with the revival of
scientific knowledge that eventually ended the Dark Ages, it was
realized that this situation was unresolvable according to Zeno's
paradox.

Of course, the 'infinite demons' theory works in many problems of
engineering significance, but a real understanding requires that the
ether be introduced into the analysis at some point. The ether
concept, of course, explains why planes fly more efficiently at higher
altitudes, and, of course, is an absolute necessity when studying
orbital and interplanetary travel, where (it is believed) many of the
lift demons are unable to breathe. Hope that settles the question.

And in a follow-up:

Do shock waves act like cattle prods and make the lift deamons
try to escape? Is why supersonic aircraft are so fast and so
noisy. Why do blimps work? -D

[Moderator's note: Blimps work because the lift demons can cling to
the seams in the envelope and the wires for the advertising lights, of
course. And there are specialized supersonic lift demons (they hang
around Harley-Davidsons when there's nothing flying) that are a little
noisy. Transonic drag rise/lift reduction is caused by the subsonic
lift demons handing off to the supersonic lift demons, since there are
only so many places for the demon to grab on. I'd never thought about
the shock waves--any ideas out there? MFS]

But according to that theory, how do bees manage to fly, having no feathers or
hairs on their wings?
;-)

--
__________ ____---____ Marco Antonio Checa Funcke
\_________D /-/---_----' Santiago de Surco, Lima, Peru
_H__/_/ http://machf.tripod.com
'-_____|(

remove the "no_me_j." and "sons.of." parts before replying