Question to Mxmanic

You really are dense.

The airmass is rising relative to the ground and carrying the wake with it
(minus its sink) so they can cancel out. We (pilots) are maintaining our
altitude relative to the ground-descending relative to the airmass, but not
relative to the ground.

mike

"Mxsmanic" wrote in message
...
mike regish writes:

We have. Rising air. It happens all the time over the plowed cornfields I
fly over. The plane doesn't also rise with the air because we are
maintaining out altitude above the ground.

Therefore you are descending into your wake. QED.

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Not always.

mike

"Mxsmanic" wrote in message
news
Jim Stewart writes:

*Every* pilot (at least in the US) learns steep turns
in the context of the FAA's practical test standard.
That's a steep turn while holding your altitude +/- 100
feet.

If you meet your wake, you're descending.

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writes:

Did you use Microsoft Air Simulator to do this?

You haven't answered my question.

OK, now wave your hand through a real fluid, I'd suggest water.

Did it feel the same as waving your hand through air?

If you look in books on aerodynamics, you'll find that air is effectively an
incompressible fluid at low speeds, such as those encountered in small
aircraft. It isn't until you get to the transonic range that compression
starts to be an issue, and the rules change substantially at and beyond the
speed of sound.

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In rec.aviation.piloting Mxsmanic wrote:
writes:

Did you use Microsoft Air Simulator to do this?

You haven't answered my question.

What question?

OK, now wave your hand through a real fluid, I'd suggest water.

Did it feel the same as waving your hand through air?

If you look in books on aerodynamics, you'll find that air is effectively an
incompressible fluid at low speeds, such as those encountered in small
aircraft. It isn't until you get to the transonic range that compression
starts to be an issue, and the rules change substantially at and beyond the
speed of sound.

Have you ever looked in a book?

--
Jim Pennino

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On Apr 16, 3:59 pm, Tom L. wrote:
The big question is "why does the wake turbulence descend?"
Is the air volume inside the vortices denser than surrounding air?

Found it, Tom. Ref:

http://www.airpower.maxwell.af.mil/a...ug/carten.html

"Cruise altitude vortices usually level off at about 1000 feet below
the altitude of the aircraft as their density comes into equilibrium
with that of the surrounding air. Decay processes then take over. "

Regards, Kev

"Mxsmanic" wrote...
Rip writes:

Please provide a reliable reference for that staement.

Every reference I can find mentions it.

Interestingly, MSFS will simulate this very effect in a C172 or a Baron in a
level 360 degree turn.

I wonder why the software would imitate something that cannot happen in real
life?

BDS

On the other hand, wingtip vortices are a well-researched topic, and
if a Boeing 727's is only 9' in radius,

cite? I remember seeing pictures of wingtip vortices (of fair sized
aircraft) and they looked like they were more than 18 feet across.

Jose
--
Get high on gasoline: fly an airplane.
for Email, make the obvious change in the address.

"Kev" wrote in message
ups.com...
On Apr 16, 3:59 pm, Tom L. wrote:
The big question is "why does the wake turbulence descend?"
Is the air volume inside the vortices denser than surrounding air?

Found it, Tom. Ref:

http://www.airpower.maxwell.af.mil/a...ug/carten.html

"Cruise altitude vortices usually level off at about 1000 feet below
the altitude of the aircraft as their density comes into equilibrium
with that of the surrounding air. Decay processes then take over. "


Don't underestimate the value of the words "usually" and "about" in that
sentence. You are still trying to absolutely describe something that is very
dynamic.

Tim writes:

Interestingly, MSFS will simulate this very effect in a C172 or a Baron in a
level 360 degree turn.

Will it? It doesn't simulate wake turbulence generally, why would it simulate
this?

I wonder why the software would imitate something that cannot happen in real
life?

So do I.

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On Apr 17, 12:02 am, Jose wrote:
On the other hand, wingtip vortices are a well-researched topic, and
if a Boeing 727's is only 9' in radius,

cite? I remember seeing pictures of wingtip vortices (of fair sized
aircraft) and they looked like they were more than 18 feet across.

Sorry was not cited here, but in other posts. To repeat:

http://www.airpower.maxwell.af.mil/a...ug/carten.html

Yes, I would've thought much bigger too, but then they wouldn't be as
much a threat so far behind an aircraft if they expanded quickly in
diameter. Apparently if flaps or spoilers aren't used, the danger
area behind a 747, for example, extends many more miles than we're
usually taught:

http://www.nasa.gov/centers/dryden/a...4-14-DFRC.html

Still haven't found much on really light aircraft ( 26,000 lbs), but
the concept should be the same, albeit at a much smaller amplitude.
There are equations for calculating the vortex, but they seem hard to
get at on the web.

Of interest: wingtip vortices were first formally written about in
1907 (!), and the use of vertical fins to cut down the drag on wings,
dates over a decade before that.

Regards, Kev