Turning on the Light

Everyone's born with a light bulb hanging in the air over their heads,
just like in the cartoons. Except it's not on. That's our normal
state, fumbling our way through life mostly in the dark. What turns on
the bulb is knowledge -- the stuff you know. Not money. You can spend
a ton of money and a lot of years for a fancy diploma and still be a
pretty dim bulb. And not the stuff you THINK you know. While
Conventional Wisdom is usually based on a kernal of truth, CW itself is
usually dead wrong, even though everyone thinks otherwise.

Kid about ten wearing a wrist-watch with more dials than a steam
locomotive, probably to convince someone he's worth kidnapping. Little
girl orbiting around him like a tearful moth because the catfish ate
Nemo. Abandoned in the office to wait for... something. Wandered into
the hangar because it belongs to his dad, which means it's okay to
pester the hired help.

No, I'm not Santa Claus. To her. Probably because of the beard.

Santa's hangar is north of here and his beard is all white and he's a
lot nicer than I am. Older too. Of course I know him; we were in 'nam
together. And the catfish didn't really eat him, it's just a game fish
play. Why? Because they get bored of being in that tank all the time.
How can they breath under water? Because they don't know it's water;
they think it's just thick air. Can you see the air? Well, you're
swimming in it right now, just like the fish in the tank in the office.
This whole hangar is filled with air but you can't see it. And you
have to hold on to your brother's hand because I don't want him to get
lost.

Air weighs fourteen point seven pounds per square inch. From him, a
bit miffed because she had now latched onto his hand.

Yeah, but that's only for a square INCH. To make an airplane fly you
gotta know how much it weighs by the square FOOT. Which doesn't shut
him up as long as I'd hoped. In less than a minute he says, two
thousand one hundred and sixteen pounds per square FOOT, sounding a bit
surprised. He probably figured it out on that watch of his.

That's right, I tell him. Which is MORE than this airplane weighs. Or
would, if it had an engine and fuel and plex in the windows and stuff
like that. Air is heavy stuff. More than a ton per square foot and
here we are swimming around in it.

But it's... equal, he sez, struggling a bit, although the bulb is
starting to glow.

Yeah. Like the fish. So all you gotta do is make it UNEQUAL and the
plane will fly.

Lift... he starts to chant something else he's memorized without
understanding but I shut him up with a wave of my hand. Lift is just
the name we give to the amount of the inequality; the difference in
pressure.

Lost him.

Basic PA-28, wings got about a hundred and sixty square feet and the
plane weighs about a ton, all up. Lift has to equal the weight, I
hint. The little fart shakes off his sister, whips out a CALCULATOR
and starts punching the buttons! And here I thought he was doing it in
his head.

He comes up with number that sounds about right -- so many pounds per
square foot.

"NOW you can do the square inch thing," I tell him. He eventually
comes up with a figure that I convert to ounces. It's meaningless to
him. I hand him my pounch of Prince Albert. "About that much and we
can fly." He weighs it in his hand. The bulb is lighting up the
whole hangar.

"If we move the wing fast enough..." he sez.

We...

If we move the wing through the air fast enough to create a mere ounce
and a half difference in pressure for each square inch the lift will
exceed the weight and that's called 'flying.'

A woman calls out from the door to the office and the little girl drags
her brother away, his bulb glowing brightly. The little girl abandons
him before they get there, runs ahead saying, "He knows SANTA CLAUS!"

No wave good-bye. No word of thanks. But the 'we' says the
brotherhood of airman had just increased by one.

-R.S.Hoover

wrote in message oups.com...
....

No wave good-bye. No word of thanks. But the 'we' says the
brotherhood of airman had just increased by one.

-R.S.Hoover


Thanks again!
--
Dan DeVillers
http://www.ameritech.net/users/ddevillers/start.html


..

Santa You do come up with some good stories!
John
;-)


No wave good-bye. No word of thanks. But the 'we' says the
brotherhood of airman had just increased by one.

-R.S.Hoover

When I was a kid, I never asked why airplanes fly. I didn't care why. It
was just the nature of airplanes. They flew. I would ride my bicycle down
to the airport and watch them. Sometimes for hours. Never asking why.

Now, decades later, I can talk for hours about those 'why's. I can show you
in the mathmatics the 'why's of it all. It's really elagent if you just
look at it.

Yet, if I twist around and look back at those big old wings, hanging there
seemingly motionless as the world rotates under us, the light comes on.
Suddenly, I KNOW why airplane fly. It's magic.

Rich

wrote:
Air weighs fourteen point seven pounds per square inch.

Grumble

That's air's mean pressure at sea level, not it's "weight". Weight is
measured in units of force or mass, depending on the context.

Air's mean density at sea level is roughly 1.2 kg/m^3, which is the relevant
measure for teaching the rudimentary facts of flight. A plane stays in flight
by pushing air downward. A balloon flies by making the mass within its volume
less dense than the surrounding air. In both lighter than air and heavier
than air flight, air pressure does not directly enter into the calculations -
but air density does. And that's a far smaller quantity - about 1 ounce per
cubic foot at sea level.

No harm done to the kid, though. You appear to have given him some insight
into how powerful small pressure differentials can be. Nice story, otherwise.

Richard Isakson wrote:

When I was a kid, I never asked why airplanes fly. I didn't care why. It
was just the nature of airplanes. They flew. I would ride my bicycle down
to the airport and watch them. Sometimes for hours. Never asking why.

Now, decades later, I can talk for hours about those 'why's. I can show you
in the mathmatics the 'why's of it all. It's really elagent if you just
look at it.

Yet, if I twist around and look back at those big old wings, hanging there
seemingly motionless as the world rotates under us, the light comes on.
Suddenly, I KNOW why airplane fly. It's magic.

Rich



First time I had that thought was in the back of a 727 watching the land pass.

All the aerodynamics, engineering, knowledge of what's happening and why,
simply gets overwhelmed - by the magic of it all.


Hey Rich?
Want to hop on a bike and ride out to the airport?


Richard

"The mind is not a vessle to be filled, but a fire to be lighted".

"Richard Lamb" wrote

First time I had that thought was in the back of a 727 watching the land
pass.

For me, a 707, then shortly after, a C-150, with my sister and her new
ticket. That flight was over way too quickly. g
--
Jim in NC

"Jim Logajan" wrote

A plane stays in flight
by pushing air downward. A balloon flies by making the mass within its
volume
less dense than the surrounding air. In both lighter than air and heavier
than air flight, air pressure does not directly enter into the
calculations -
but air density does.

Oh, here we know again- Bernoulli, or not to Bernoulli.
--
Jim in NC

And, now, the kid's hopes will be dashed when his mother tells him he cannot
fly unless he east his veggies.