Why airplanes taxi

On Feb 11, 6:20*pm, Clark wrote:
terry wrote in news:5f088abd-cbda-4dba-a3dd-
:

[snip happened]

Not to detract from your lecture but up in the northern hemisphere we tend to
use 28.96 as the molecular weight of air. Perhaps some of the lighter
molecules settle out in the south? :-)

I shouldnt have been so precise. its just a number I use frequently in
my work that allows for 0.83 v/v % water.( an average value for my
neck of the woods)

After all is said and done, perhaps someone should ask MX to 'splain why
sonic velocity in the atmosphere depends only on temperature...

good luck with that one!

terry writes:

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?

No. According to the POH (the sim version and the real version are the same),
4500 feet is enough for any situation, so as long as I have at least 4500
feet, I'm fine.

Do you know how to work out what your density altitude is?

I have a calculator and an E6-B to work things out should that really become
necessary.

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.

I stay close enough to the center of the envelope that this is never a factor.
It's a lot easier than pushing the envelope and having to do a truckload of
calculations before every flight just to see if I can squeak by.

On Feb 10, 9:47 am, Mxsmanic wrote:
So, overall,
the air is always warmest at the surface. There are some anomalies higher in
the atmosphere.

Not always. Not at all always. We frequently get inversions where the
air 1000' feet up is much warmer than that on the surface. Inversions
are very common here, and I would imagine they're common most anywhere
away from the equator. We've had days here, in the winter, where we've
left the ground where the temp is -20°C, and found -18°C at 3000' agl.
Often I find the winds howling at 25 or 30 knots just 200 feet above
the surface, while the wind on the ground is zilch and the temp is 25
degrees colder.
"Always" just doesn't deal with reality. Works on a sim, I
suppose.

Parcels of air that rise in the atmosphere will cool as the pressure in the
atmosphere drops, and this is responsible the adiabatic lapse rate.

If you'd ever studied meteorology (Commercial Pilot
groundschool) you'd know that the temp falls with altitude until we
reach the tropopause. Then it starts rising until we reach the
stratopause, where it starts to fall again through the mesosphere, and
once we reach the thermosphere it rises again and keeps on rising,
though the density is so low that the actual heat content is minimal.
See this:
http://www.ux1.eiu.edu/~cfjps/1400/FIG01_019.JPG

In both cases, the correlation is between temperature and altitude, not
temperature and pressure.

If pressure rises, so does temperature. The air coming down
off the Rockies here rises in temperature as its pressure rises in the
descent. This is part of the chinook phenomenon's equation. The rest
of that equation has to do with condensation of the vapor on the west
side of the mountains, which releases the heat of evaporation back to
the atmosphere so that the air's temperature fall is minimal as the
air is forced upward by the terrain. So when it gets to 3000' on this
side, it's MUCH warmer and drier than it was at 3000' on the west
side. The snow evaporates (sublimates) in that warm, dry air. It
doesn't have a chance to melt.
The atmosphere is much more complex than you think.

Dan

On Feb 12, 5:26*am, Mxsmanic wrote:
snip
I stay close enough to the center of the envelope that this is never a factor.
It's a lot easier than pushing the envelope and having to do a truckload of
calculations before every flight just to see if I can squeak by.

come on live a little, push that envelope, you only live once. dont
die wondering
Whats the worst thing that could happen?
Terry

On Feb 12, 5:26*am, Mxsmanic wrote:
terry writes:
snip

Terry wrote a lot of things which you have not commented on in your
reply. Do we take that you have finally realised you were talking
crap about the gas laws not applying in the atmosphere or in space?
Terry

Bertie the Bunyip wrote in
:

Mxsmanic wrote in
:

WingFlaps writes:

So how do you explain the rather well known lapse rate?

It depends on which lapse rate you have in mind.


The one which states that as the temperature rises, the two molecules in
your head take a siesta.

Bertie


When did his intelligence double to two molecules?

Mxsmanic wrote:

I stay close enough to the center of the envelope that this is never a factor.
It's a lot easier than pushing the envelope and having to do a truckload of
calculations before every flight just to see if I can squeak by.

Real pilots do the "truckload of calculations" all the time.


--
Jim Pennino

Remove .spam.sux to reply.

On Feb 11, 12:37 pm, wrote:
We've had days here, in the winter, where we've
left the ground where the temp is -20°C, and found -18°C at 3000' agl.

My mistake. It was -20°C on the ground and +18°C at 3000' agl.
A 38° difference. A difference in the "wrong" direction.


Dan

terry writes:

come on live a little, push that envelope, you only live once.

There are old pilots and bold pilots, but there are no old, bold pilots.

You sound very much like the type of pilot that the FAA warns about.

terry writes:

Terry wrote a lot of things which you have not commented on in your
reply. Do we take that you have finally realised you were talking
crap about the gas laws not applying in the atmosphere or in space?

I didn't bother to read the rest. I'm not sure who "we" might be, but Terry
can certainly take it anyway that Terry wants.