The Impossibility of Flying Heavy Aircraft Without Training

Two years ago when I was in college I used to read science journals for
fun... One particular, just published within the past two years
(spring '04?) caught me.

It discussed the Bernuolli theory of flight- and (if I recall) quite
conclusively proved that one of the _fundamental_ assumptions of the
Bernuolli theory- that air that travels path over the top of the wing
is flowing appreciably faster than air that flows over the bottom- is
simply incorrect in a compressible fluid....

Obviously, you should take this with a grain of salt because A- this is
my first post on this board and B- I can't remember either the journal
or the exact date... but take it for what its worth

Most aerodynamic equations dealing with low subsonic speeds treat air as an
incompressible fluid because compressibility doesn't have a significant
effect until you approach sonic speeds.

Isn't compressiblity what causes pressure changes (absent temperature
changes)?

Jose
--
Money: what you need when you run out of brains.
for Email, make the obvious change in the address.

On 2006-03-01 20:42, Jose wrote:
-snip-
When you consider how hard gremlins are, and how soft feathers are, it's
a natural that feathers repel gremlins, and lift is sometimes
erroniously attributed to feathers. Many researchers have been down
this path, and there is a large body of accepted literature in support
of the feathers theory. At low speeds, the feather theory and the
gremlin theory give pretty much the same answers, but at high enough
speeds the relationship breaks down and the feather theory gives
erronious answers. This is where gremlin theory shines (it should be
noted that lift fairies are just gremlins gone bad).

Gremlin theory holds the potential for explaining a lot of aviation that
is otherwise unexplainable, but experiments are difficult and fraught
with peril. However, I would be happy to conduct the appropriate
research. Send grant money to Jose, care of Usenet.

Jose

I'm with you on the gremlins theory; since the feathers theory can be
proven to work or not in at least two disparate ways:

1. Why is is that a feathered prop does not provide more lift than an
unfeathered one? If the feather theory was correct, it would make sense
to feather all props to increase lift.

2. Manned flight would have been possible long ago, by just applying
feathers to the human body; while some think this is difficult to
achieve, I've read several successfull reports using tar for this
purpose. (It is the removing thereof that is the difficult part.)
None of the tarred aviators seemed to fly wery well afterwards, so the
feathers have been demonstrated not to work in this case.

(I note that the excact mass of feathers may have been too small,
according to calculations in this group, so I invite anyone to try this
method for themselves, to prove or disprove it.)

/Rolf

wrote:
Greg Esres wrote:
The disk is constantly transferring momentum to the air below it,
which is transferring it right back after bouncing off of the floor.


There is no momentum change here because there is no *net* force on
either the air or the disk. The molecules next to the disk have a
pressure equal to the weight of the disk below it and the actual disk
above it. There is no net force and thus no momentum change.

Pressure never equals weight for the same reason that voltage
never equals power.

To be precise, the upward force the disk is the difference
in the pressure below the disk less the pressure above, multiplied
by the area of the disk. The downward force is the weight of
the disk which is the product of the mass of the disk times
the local acceleartion due to gravity. The disk stops moving when
the two forces are equal.


Momentum = mass * velocity, and the vertical velocity of the air and
the disk are zero.

Force is defined as the time rate of change of momentum. Therefor
when the disk is neither accelerating nor changing mass there is
no force acting on it.

So what holds it up? ;-)


Lift pixies !

On Wed, 22 Feb 2006 06:15:59 -0600, Immanuel Goldstein
wrote:

The Impossibility of Flying Heavy Aircraft Without Training

Nila Sagadevan | February 21 2006

Nila Sagadevan is an aeronautical engineer and a qualified pilot of heavy aircraft.

And absolutely no common sense, but being this has to be a troll what
would you expect.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

On Fri, 24 Feb 2006 02:35:13 -0600, Immanuel Goldstein
wrote:

On 2/22/2006 11:07 AM, Robert M. Gary wrote:
A local pilot at our airport who owns a small Cessna 210 went to Boeing
737 school a few years back. He was able to shoot approaches to mins
and fly quite nicely without any heavy iron training outside of some
books and manuals he picked up. Of course, the work gets harder when
the instructor starts to simulate things failing. Airline pilots are
grossly over paid 99% of the time and grossly under paid 1% of the
time. As long as everything is working its pretty easy.


Thank you, Robert. This is exactly the reason I chose these groups for my
_original_ post. I have a couple of follow-up questions.

The local pilot you mentioned was already _quite_ capable of flying a Cessna
210, before attempting a 737. Would someone with little or no flight experience
be able to fly a 737, 747, or 757, and also make steep dives and sharp turns?

The *big* mistake here is making some wild assumptions.
1. Assuming the pilot is worried about exceeding some or any of the
aircraft's limitations. (afraid of breaking it)
2. Afraid of injury. (He plans on dying.)
3. That all maneuvers are performed according to the book.

So, steep dives and sharp turns are indeed easy once you have
determined the pilot does not care what happens to the airplane, the
passengers, what every they might hit, or himself.

Standard Boeing commercial aircraft have locks on the cockpit doors. How
difficult would it be break one down?

Before 9/11 they often stood open whether they were supposed to be
shut or not.


What are the chances that 8 trained pilots and co-pilots, with military
backgrounds, could be physically overpowered by a few thugs with box-cutters?

Quite good when you consider back then the training was to try and
keep the hijacker calm and reason with them, particularly if they have
a hostage. The rule was, "don't make waves" as we might get sued if
any passengers get hurt through your actions.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

On Mon, 27 Feb 2006 21:28:52 -0500, Bryan Martin
wrote:

I don't know if it was the first time, but it happened once back in the
early '80s in, I think, Arizona. I believe it was a PSA DC-9. A disgruntled
ex-employee snuck a gun on board and forced his way into the cockpit and
shot the flight crew and then dove the plane into the ground. Of course in
that case the hijacker had a real weapon and about the only thing that might
have stopped him was someone else with a gun. Then of course there is the
case of the FedEx DC-10 where the crew barely managed to prevent a nut case
soon to be ex-employee from doing the same.

The 9-11 hijackers weren't even armed. No mater what anybody says, a box
cutter is not a weapon. The only way you can do any serious damage with one
is if your victim stands there and lets you do it. Real weapons in the hands
of the crew could have stopped them cold. The passengers could have rushed
them and put a stop to it. This last scenario has happened at least twice
since 9-11. The "shoe bomber' was subdued by passengers. In another case a
drunk passenger tried to force his way onto the flight deck and was stopped
by several passengers who damn near beat him to death.

He was DOA at the airport. Said his heart failed as I recall.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

in article ,
at wrote on 2/27/06 12:10
PM:


Bryan Martin wrote:
...
Now we all know just how stupid this policy
was. They should have known it before, 9-11 is not the first time a hijacker
has taken over an airliner and deliberately crashed it.

When was the first time a hijacker took over an airliner and
deliberately crashed it?

That particular scenario had been considered plausible since
at least eh early 1960's and was one of the design criteria
for the outermost containment domes at nuclear power plants.

Dan wrote:
Richard Lamb wrote:
Bryan Martin wrote:


Bryan,

Ex-nay!

Or wander over to alt.politics to feed the loons...

I brought up this whole Bernouli mess just to get
rid of these guys.

It worked quite well.

Now don't screw it up again!

Richard

Isn't a Bernouli what an Arab wears?

under his theorum :-)

On Tue, 28 Feb 2006 at 07:42:32 in message
. com,
wrote:

For a fan in open air the momentum of the air moving through the
fan is equal and opposite to the momentum of the air moving around
the fan to replace the air removed from the front of the fan. There is
no net momentum change in the air. For ducted flow that returns the
air to the front fo the fan, the net momentum is also zero. Net flow
and
net momentum through any closed loop is zero--else the 'loop'
is not 'closed'.

Followjng a wing in level flight, the downward momentum of the
air in the downwash is equal and opposite to the upward momentum
of the air to either side that moves up to replace the air that washes
down. There is no net momentum change in the air.

This whole discussion is becoming weird. The power required to drive a
fan goes somewhere. There is and must be a net increase in the air
velocity across the fan so there is a change of momentum from the air
entering to the air leaving. The power input results in a momentum
change. This principle applies to fans, helicopters, wings and other
things - even rowing! The air that leaves the driven fan, jet engine,
ducted fan, wing is the result of the thrust or vice versa, how ever you
like to think of it.

However, that speeded up air dissipates itself in the atmosphere
gradually giving up energy to the surrounding air as it all eventually
steadies down again. What does that do? Well in the ultimate I guess it
raises the temperature of the atmosphere slightly!

An airscrew does much the same. It captures air from a tube somewhat
larger that its diameter, speeds it up and it goes out the back faster
then it came in. if you had a closed circuit like a wind tunnel it still
requires power to accelerate the air to the required speed. Less than an
open system though a carefully shaped return duct will slow the air down
again ready to be accelerated again. In that cases the losses have to be
made up.

What is a wing but a kind of linear fan?
--
David CL Francis

On Mon, 27 Feb 2006 at 09:29:48 in message
.com,
wrote:

Conservation of angular momemtum causes the air to continue swirling
after the aircraft has passed. Once the pressure changes caused by
the passage of the aircraft have died out and the pressure restored to

ambient the net downward flow from the entire aircraft is equal to net
upward flow from the entire aircraft, provided the aircraft is in level
flight.
The point missed her is that the pressure changes and velocity changes
to the air after the wing has passed only die away because energy is
lost far away from the wing's immediate influence. Making a big deal
about the fact that the disturbance disappears and thus the atmosphere
stays much as it was before (only a bit hotter) seems to suggest that
there is no momentum change as the wing does its work. Perhaps this is
what is meant but it cannot be used as proving in any sense that the
wing has no net effect.

The same argument would not be very convincing in demonstrating that the
air going into a fan dissipating 1000s of HP is the same going out as it
was coming in!
--
David CL Francis