Why airplanes taxi

writes:

And to answer your next post before you post it:

What molecules?

http://en.wikipedia.org/wiki/Outer_space

"While not being an actual perfect vacuum, outer space contains such sparse
matter that it can be effectively thought of as one. The pressure of
interstellar space is on the order of 10 pPa (1×10-11 Pa)."

So, no molecules. And no friction.

Even if you don't wish to consider the hard vacuum of space as perfect, with a
pressure that is 10,000,000,000,000,000 times lower than that of Earth at sea
level, the friction should be also that much lower, and thus the speed of a
taxi should be trillions of times faster. The speed of light is only fifteen
million times faster than a 40-knot taxi, so nearly the speed of light might
well be achieved long before any residual friction could have any effect.

Robert M. Gary writes:

On Feb 6, 9:24*am, Mxsmanic wrote:
writes:
Fixed-wing aircraft taxi because their wheels reduce friction as they
move forward on the ground.

So, logically, spacecraft in the frictionless environment of outer space
should immediately accelerate to the speed of light.

No, it still takes energy to accelerate a mass, even in a frictionless
environment.

But the original post said that aircraft taxi because their wheels reduce
friction. No mention of energy or force. So if the statement is true,
movement results from a lack of friction alone, so zero friction should
produce infinite speed (or lightspeed if one allows the speed of light as an
absolute upper limit).

However, space (especially near space) is not frictionless.

Nor does friction produce acceleration. QED.

Gee, where would the energy come from to cause the acceleration?

On Feb 6, 2:00*pm, Mxsmanic wrote:
writes:
And to answer your next post before you post it:

What molecules?

http://en.wikipedia.org/wiki/Outer_space

"While not being an actual perfect vacuum, outer space contains such sparse
matter that it can be effectively thought of as one. The pressure of
interstellar space is on the order of 10 pPa (1×10-11 Pa)."

So, no molecules. *And no friction.

Even if you don't wish to consider the hard vacuum of space as perfect, with a
pressure that is 10,000,000,000,000,000 times lower than that of Earth at sea
level, the friction should be also that much lower, and thus the speed of a
taxi should be trillions of times faster. *The speed of light is only fifteen
million times faster than a 40-knot taxi, so nearly the speed of light might
well be achieved long before any residual friction could have any effect.

"Phil J" wrote
...


Wrong. Wrong. Wrong.

Fixed-wing aircraft can only achieve a stable taxi by keeping the CG
between the forward and aft wheel points(WPs). This is why it is so
important in aircraft design that the WPs be placed correctly. In
the early days of aviation some designers placed all the wheels to one
side of the CG, with the result that the aircraft was dynamically
unstable in taxi. Sadly, many lives were lost before this phenomenon
was understood.

If the CG is placed correctly in relation to the WPs, the aircraft
establishes taxi by moving the Earth beneath it. Turns are achieved
by rotating the Earth. Flight is achieved by dropping the Earth down,
and a landing is made by lifting it back up. Aerobatics involve
combinations of lifting, dropping, and rotating.

I hope this clears things up for everyone.

Phil


Hah...hah....
This is called the pilot's perspective: (s)he sits in the cockpit and the
earth performs the requisite manoevers.

Phil, to support your theory, I can tell you the earth weighs 130
pounds in my gravitional field (that's before breakfast. It gains a
little after that.).


On Feb 6, 1:58*pm, Phil J wrote:
On Feb 6, 10:19*am, wrote:

Fixed-wing aircraft taxi because their wheels reduce friction as they
move forward
on the ground.

Wrong. *Wrong. *Wrong.

Fixed-wing aircraft can only achieve a stable taxi by keeping the CG
between the forward and aft wheel points(WPs). * This is why it is so
important in aircraft design that the WPs be placed correctly. * In
the early days of aviation some designers placed all the wheels to one
side of the CG, with the result that the aircraft was dynamically
unstable in taxi. *Sadly, many lives were lost before this phenomenon
was understood.

If the CG is placed correctly in relation to the WPs, the aircraft
establishes taxi by moving the Earth beneath it. *Turns are achieved
by rotating the Earth. *Flight is achieved by dropping the Earth down,
and a landing is made by lifting it back up. *Aerobatics involve
combinations of lifting, dropping, and rotating.

I hope this clears things up for everyone.

Phil

On Feb 6, 11:24*am, Mxsmanic wrote:
writes:
Fixed-wing aircraft taxi because their wheels reduce friction as they
move forward on the ground.

So, logically, spacecraft in the frictionless environment of outer space
should immediately accelerate to the speed of light.

http://en.wikipedia.org/wiki/Inertia
--
Gene Seibel
Gene & Sue's Flying Machine - http://pad39a.com/gene/
Because we fly, we envy no one.

wrote:
Fixed-wing aircraft taxi because their wheels reduce friction as they
move forward
on the ground.

:-) I am feeling profound today...

So - how much was the bet for and how many posts do you need to win it?

Mxsmanic wrote in
:

writes:

Fixed-wing aircraft taxi because their wheels reduce friction as they
move forward on the ground.

So, logically, spacecraft in the frictionless environment of outer space
should immediately accelerate to the speed of light.


No, it takes a few minutes. Don't you watch star trek?

Bertie

Mxsmanic wrote in
:

writes:

Space isn't frictionless dummy.

Where does the friction come from?

Klingons, fjukkwit!


Bertie

Mxsmanic wrote in
:

writes:

And to answer your next post before you post it:

What molecules?

http://en.wikipedia.org/wiki/Outer_space

"While not being an actual perfect vacuum, outer space contains such
sparse matter that it can be effectively thought of as one.


A bit like the inside of your skull.

Bertie