Turning on the Light

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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

[.Blueskies.]

> 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


..

[UltraJohn]

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

[Richard Isakson]

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

[Jim Logajan]

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 Lamb]

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

[Richard Lamb]

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

[Morgans]

"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

[Morgans]

"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

[COLIN LAMB]

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

[J.Kahn]

wrote:
> 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
>

One day if you want to get a book for a teenager interested in the
science of aviation get them this one called The Miracle of Flight:

http://www.amazon.com/gp/product/1552979822/qid=1138640552/sr=2-1/ref=pd_bbs_b_2_1/102-5177975-8168159?s=books&v=glance&n=283155

It's basically an explanation of aerodynamics and flight mechanics up
the Reynolds Number scale from insects to birds to jets. Beautiful
photos and written more or less for the interested layman. Very simple
and effective explanation of Reynolds Number and how air viscosity is
the secret behind insect flight, along with flapping wing mechanics. It
shows how the aerodynamic tools of airplanes like slats and vortex
generators are already used by nature of one species of bird or other.
My favorite aviation book.

John