Mxsmanic , IFR sensations, and some other stuff

Mxsmanic wrote:

Jim Stewart writes:

So then that makes you both rude and dishonest.

You're entitled to your opinion, and I'm entitled to mine.

Your rudeness and dishonsty are facts, not opinions. So is the
fact that you are an obstinate cretin unable (and too dishonest)
to grasp such simple concepts as applying to yourself. HTH.

Michael Ash wrote:

At sea level the atmosphere pushes down with about 14.7 pounds of force
for every square inch of exposed surface. On the average man, this works
out to about 43,000 pounds, all the time. Why aren't your crushed by this?

I'm too emotionally stable to be crushed by such a trivial thing.

Besides, I push back with equal force.

"Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way D0t C0m wrote

Sorry, but, at most speeds the air "over the top" gets there well before
the
air flowing under. Do the math. It's not that hard.
Circulation is a good way to model the effects.

You're right - I had that sdrawkcab...

BDS

Interesting phrase, "pushes down". Why would you think atmospheric
pressure pushes down?






On May 22, 11:52 am, Michael Ash wrote:
In rec.aviation.student Gig 601Xl Builder wrote:



Mxsmanic wrote:
Stealth Pilot writes:

aeroplanes fly because of lift generated by pressure differences on
the wing surfaces.

Airplanes fly because the wings divert the air through which they pass
downwards, creating a downwash and exerting a force in doing so that engenders
an opposite force that is lift.

... these pressure differences are caused by the shape
of the aerofoil of the wing ...

The air is diverted because the wing has a positve angle of attack. It can be
perfectly flat and it will still generate lift.

If that were the case a 747 would have to be producing over 250,000
pounds of force straight down. Why then am I not crushed when a 747
flies over me?

At sea level the atmosphere pushes down with about 14.7 pounds of force
for every square inch of exposed surface. On the average man, this works
out to about 43,000 pounds, all the time. Why aren't your crushed by this?

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

BDS wrote:
There is an interesting article in Flying magazine by Peter Garrison that
talks about lift theory.

I thought that one of the most interesting points he made was that the
lift force generated by an airfoil is greater at the optimum angle of
attack than would be the force imparted to it if you were to move it
through the air perpendicular to the air flow at the same speed.

I first experienced this as a kid, sticking my hand out the car window with
the thumb as a leading edge, forming a crude airfoil.

When at the right shape and angle of attack, the lift is amazingly strong.
I always found it remarkable that when my hand was completely
perpendicular to the wind, the force didn't seem as strong.

Definitely a visceral lesson in lifting versus stalling.

Steve Foley wrote:

http://en.wikipedia.org/wiki/User:Agateller

Seriously: Have any of you guys read "A Confederacy of Dunces"? Add
this stuff to the Wikipedia page above:

"I mingle with my peers or no one-and since Ihave no peers, I mingle
with no one..."

"I dust a bit...in addition, I am at the moment writing a lengthy
indictment against our century. When my brain begins to reel from my
literary labors, I make an occasional cheese dip."

"I have succeeded in in initiating several work-saving methods. I have
taken to arriving at the office one hour later than I am expected. ... I
find that in arriving later, the work which I do perform is of a much
higher quality. My innovation in connection with the filing system must
remain secret for the moment, for it is rather revolutionary..." -
Ignatius J. Reilly


-c
"My life is a rather grim one. One day I shall perhaps describe it to
you in great detail."

On May 22, 5:36 pm, Some Other Guy wrote:
BDS wrote:
There is an interesting article in Flying magazine by Peter Garrison that
talks about lift theory.

I thought that one of the most interesting points he made was that the
lift force generated by an airfoil is greater at the optimum angle of
attack than would be the force imparted to it if you were to move it
through the air perpendicular to the air flow at the same speed.

I first experienced this as a kid, sticking my hand out the car window with
the thumb as a leading edge, forming a crude airfoil.

When at the right shape and angle of attack, the lift is amazingly strong.
I always found it remarkable that when my hand was completely
perpendicular to the wind, the force didn't seem as strong.

Definitely a visceral lesson in lifting versus stalling.

I have a copy of that article here. Very, very good. The
coefficient of lift, as he described it, was a ratio related to the
lift generated by a unit area of wing compared to the flat-plate drag
created by the same unit area perpendicular to the airflow. The Wright
brothers did this in their wind tunnel, so they were able to develop
efficient airfoils. A common airfoil (NACA 23012, IIRC) has a max lift
coefficient of 1.8 , which means that it generates 1.8 times the lift
as the drag of the perpendicular surface of the same area.
He made things really clear when he pointed out that this is why
boats and ships no longer use paddlewheels. The wheel will produce
forward thrust equivalent to the power required to force the paddle
back through the water, while the propeller (they call it a "screw")
will produce much more forward thrust for the same torque required by
the paddlewheel.
So it's a process to cause the air to exert a force in a
direction perpendicular to the airflow. It fools the air, if you like,
which is why we call it an "air foil." A foil is a device to deceive.
Bernoulli is right, and so is Newton. There's a pressure
difference because of the difference in airspeeds between top and
bottom, and there's a movement of air downward to which there's an
upward reaction. The equal-transit time theory is bogus, since the
airfoil is much more efficient than that theory would imply. See this
page:
http://www.av8n.com/how/htm/airfoils.html
And, again, Mxmanic has declared, for about the 12th time, that
positive AOA is necessary for lift. If this was so, and it isn't, and
he has been shown many times that it isn't, then airfoils like the
Clark Y wouldn't generate lift at AOAs as low as -4 degrees. That's
negative 4 degrees, airfoil chord pointing downward. A graph can be
found a third of the way down this page: http://lpmpjogja.diknas.go.id/kc/a/air/airplane.htm
That page also deals properly with both Newton and Bernoulli.

Dan

On May 22, 5:25*pm, Tina wrote:
Interesting phrase, "pushes down". Why would you think atmospheric
pressure pushes down?

At sea level the atmosphere pushes down with about 14.7 pounds of force
for every square inch of exposed surface. On the average man, this works
out to about 43,000 pounds, all the time. Why aren't your crushed by this?
Mike Ash

He probably picked down since down is as good a direction as any,
unless, of course, he was thinking of someone with a big head whose
top surface area measures 4.5 feet x 4.5 feet.

-Le Chaud Lapin-

I think you asserted one time or the other you had technical
training. Why then in terms of static fluid pressure would one
specify a direction?



On May 22, 9:06 pm, Le Chaud Lapin wrote:
On May 22, 5:25 pm, Tina wrote:

Interesting phrase, "pushes down". Why would you think atmospheric
pressure pushes down?
At sea level the atmosphere pushes down with about 14.7 pounds of force
for every square inch of exposed surface. On the average man, this works
out to about 43,000 pounds, all the time. Why aren't your crushed by this?
Mike Ash

He probably picked down since down is as good a direction as any,
unless, of course, he was thinking of someone with a big head whose
top surface area measures 4.5 feet x 4.5 feet.

-Le Chaud Lapin-

On May 22, 8:16*pm, Tina wrote:
I think you asserted one time or the other you had technical
training. *Why then in terms of static fluid pressure would one
specify a direction?

The fluid presses in all direction.

I was merely pointing out the fact that, if he, or the source of the
"43,000" in his post, actually thought that the fluid only presses
downward, then "43,000" would have been a much smaller value.

-Le Chaud Lapin-