Why airplanes taxi

Mxsmanic wrote in
:

terry writes:

Did I say the pressure would rise if you increased the temperature?

If it follows the combined laws, it will. But in the case of the
atmosphere, it doesn't, because the volume of the atmosphere is not
constrained, and the source of atmospheric pressure is gravity, not
the random kinetic energy of air molecules.


Nope

Bertie

Mxsmanic wrote:
writes:

Babbling nonsense.

Current estimates are the universe is about 160 billion light-years
in diameter.

If the universe isn't infinite, nothing in it can be either.

As I've said, we don't know if the universe is infinite or not.

Who is "we"?

Do you have a French rat in your pocket?

It's interesting that anyone would criticize me for making assertions about
aviation when others cheerfully make assertions about the very nature of the
universe.

Cosmologists abandonded the infinite universe theory decades ago.

Try turning off the computer and reading a few real books.

Oh, I forget, you only have real books if someone donates them to
your begging list.


--
Jim Pennino

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Mxsmanic wrote:
writes:

Air molecules don't have altimeters to tell them the altitude.

Air molecules in a tank don't have rulers to tell them the dimensions of the
tank, either.

No, they don't.

Too bad you can't understand why that is irrelevant.

--
Jim Pennino

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Mxsmanic wrote:
terry writes:

Did I say the pressure would rise if you increased the temperature?

If it follows the combined laws, it will. But in the case of the atmosphere,
it doesn't, because the volume of the atmosphere is not constrained, and the
source of atmospheric pressure is gravity, not the random kinetic energy of
air molecules.

Babble.


--
Jim Pennino

Remove .spam.sux to reply.

writes:

Who is "we"?

Mankind as a whole.

Do you have a French rat in your pocket?

No.

Cosmologists abandonded the infinite universe theory decades ago.

Cosmologists regularly change their mind, and a theory is not necessarily
reality.

Mxsmanic wrote in
:

writes:

Who is "we"?

Mankind as a whole.

Translation, you and the fungus on your yoghurt.


Bertie

Mxsmanic wrote:
writes:

Who is "we"?

Mankind as a whole.

Trivially shown to be not true.

Do you have a French rat in your pocket?

No.

Are you sure?

Cosmologists abandonded the infinite universe theory decades ago.

Cosmologists regularly change their mind, and a theory is not necessarily
reality.

A change in theory is caused by observation and measurement; those have
caused the infinite universe theory to be abandonded.

Do you have better observations and measurement?

If not, you are just babbling.

Again.


--
Jim Pennino

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On Feb 6, 5:53*pm, Clark wrote:
"Snowbird" wrote in news:cGqqj.484$aX.475
@read4.inet.fi:







"Mxsmanic" wrote ...

The corollary to that would logically be that any object entering the
atmosphere from outer space would instantly decelerate to zero speed.

Only with infinite friction.

I'm just applying your flavor of logic.

I think the meaning of logic got slighty warped as Mx's spacecraft passed
the most recent black hole. ;-)

The statement that started this thread was fundamentally incorrect. *I've
illustrated why.

Nope. Show me a wheelless airplane taxiing. Skis don't count ;-)

Would a PBY on the water do?

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there should be a "sig" here- Hide quoted text -

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Now, that's a beautiful plane. I fell in love with that plane ever
since I watched Jaque Cousteau. I fell in love with the Hughes 300
helicopter ever since I watched Jack 'what's his name' of Mutual of
Omaha.

If I ever win the lottery, the PBY would be my traveling machine for
sure.

Wil

On Feb 6, 7:53*pm, wrote:
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.

The only thread better than this one was the one where the guy wanted
to get a uniform because he'd just gotten his PPL.

He almost convinced me to want one too. lol NOT! A flight suit and a
pair of NOMEX gloves would be cool though, well maybe an A-2 jacket
and a pilots' Ray Ban.

Wil

On Feb 11, 9:07*am, Mxsmanic wrote:
terry writes:
Did I say the pressure would rise if you increased the temperature?

If it follows the combined laws, it will. *But in the case of the atmosphere,
it doesn't, because the volume of the atmosphere is not constrained, and the
source of atmospheric pressure is gravity, not the random kinetic energy of
air molecules.

For everyone else following this thread, dont worry I am not crazy, I
am just testing a theory that it is possible to teach Msx something.
So far I must admit I am a litte discouraged.
But I will just persevere for a little longer to test my teaching
skills. . Now Mxs before you take off in your simulated Baron,
do you check the takeoff performance figures in the simulated flight
manual versus the lenght of runway at your simulated departure
airport? Have you noticed they are a function of a thing called
density altitude.? Do you know how to work out what your density
altitude is ? Real pilots do this if there is any doubt they might
not have enough distance to clear the runway or any obstacles, and
since you are so obsessed with manufacturing pretended reality I am
sure you would want to be doing this also. If you did this what
you should have realised is that you are relying on the fact that the
density of the atmosphere at the particular point you are at (ie
your simulated airfield at the particular simulated temperature and
pressure conditions ) is determined only by 3 things. 1. the
temperature, 2 the pressure, 3 the chemical compositon of the
atmosphere ( ie the average molecular weight which is generally
assumed to 28.84 except for the extra dilligent who will correct for
humidity ). And the relationship between them? I think I have
already told you about 3 times density = PM/RT and where does this
equation come from? directly from the universal gas law PV=nRT by
substituting m/M for n .
Since you dont have access to a real airplane ( thank god) you could
even calculate the density of the air in your cockpit ( apartment)
with a thermometer and a barometer using the above equation. I
assure you if you do it carefully you can get a very accurate value of
the air density. ( if you must you could even open your window to
simulate an infinite volume! ).
If your answer is not something like 1.22 kg/m3 its probably because
you have underestimated M by not allowing for the methane percentage
in your apartment atmosphere.

You see your probelm is that you have this mistaken belief that the
gas law is only useful to describe a given bunch of molecule in a
balloon, probably something you picked up in grade school. but what
it really does is illustrate the point that gas molecules occupy a
volume of space that is dependant only on their number , pressure and
temperature. The forces that lead to whatever pressure and
temperature conditions exist is another subject, called meterology.
Instead of thinking that increasing the temperature should increase
the pressure ( as it would if you were talking about a fixed number of
molcules in a rigid tank) you could just as easily think that
increasing the temperature reduces the number of molecules per unit
volume, in an atmosphere where the air can expand and thus the
pressure stays relatively constant.. Either example can use the same
equation PV=nRT to describe what is happening.
Terry
PPL Downunder