Question to Mxmanic

mike regish writes:

A sign of a well executed 360 is to encounter your own wake turbulence,
although the vortex generally sinks some in the intervening time and the
turbulence is usually no more than a slight bump.

From my back-of-envelope calculations, if it's a two-minute turn, the downwash
and vortices would have descended by some 2000 feet or so by the time you
close the circle (depending on various factors). I'm surprised that there
would be anything to feel if you are maintaining the same altitude, which is
why I didn't consider this. However, if it has actually happened to you, I'll
have to review my calculations.

Anyway, while it might be interesting in real life, it would be horrifically
CPU-intensive to simulate, since it would require modeling of large chunks of
air away from the aircraft, which is as compute-bound as weather reporting.

Indeed, modeling any sort of wake turbulence would be this way, unless the
simulation were canned and provided as a couple of fixed scenarios that
wouldn't require calculation of air movements. But then you have to wonder if
it would be worthwhile, either, since it's a really bad idea to fly through
another aircraft's wake turbulence. If it's mild there's not much to
simulate; if it's heavy it's too dangerous to approach.

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

A sign of a well executed 360 is to encounter your own wake turbulence,
although the vortex generally sinks some in the intervening time and the
turbulence is usually no more than a slight bump.

From my back-of-envelope calculations, if it's a two-minute turn, the
downwash
and vortices would have descended by some 2000 feet or so by the time you
close the circle (depending on various factors). I'm surprised that there
would be anything to feel if you are maintaining the same altitude, which
is
why I didn't consider this. However, if it has actually happened to you,
I'll
have to review my calculations.

Anyway, while it might be interesting in real life, it would be
horrifically
CPU-intensive to simulate, since it would require modeling of large chunks
of
air away from the aircraft, which is as compute-bound as weather
reporting.

Indeed, modeling any sort of wake turbulence would be this way, unless the
simulation were canned and provided as a couple of fixed scenarios that
wouldn't require calculation of air movements. But then you have to
wonder if
it would be worthwhile, either, since it's a really bad idea to fly
through
another aircraft's wake turbulence. If it's mild there's not much to
simulate; if it's heavy it's too dangerous to approach.

--
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That's a keeper.

This is actually a maneuver that's demonstrated and practiced very
early in flight training, so I'm sure all pilots and student pilots
have experienced this. But your calculations are fairly correnct--a 2
minute turn won't cut it. It's usually demonstrated with a 60 degree
bank turn. I'm not sure of the timing, but i'd guess 30 sec or less.

On Apr 14, 7:11 am, Mxsmanic wrote:
mike regish writes:
A sign of a well executed 360 is to encounter your own wake turbulence,
although the vortex generally sinks some in the intervening time and the
turbulence is usually no more than a slight bump.

From my back-of-envelope calculations, if it's a two-minute turn, the downwash
and vortices would have descended by some 2000 feet or so by the time you
close the circle (depending on various factors). I'm surprised that there
would be anything to feel if you are maintaining the same altitude, which is
why I didn't consider this. However, if it has actually happened to you, I'll
have to review my calculations.

Anyway, while it might be interesting in real life, it would be horrifically
CPU-intensive to simulate, since it would require modeling of large chunks of
air away from the aircraft, which is as compute-bound as weather reporting.

Indeed, modeling any sort of wake turbulence would be this way, unless the
simulation were canned and provided as a couple of fixed scenarios that
wouldn't require calculation of air movements. But then you have to wonder if
it would be worthwhile, either, since it's a really bad idea to fly through
another aircraft's wake turbulence. If it's mild there's not much to
simulate; if it's heavy it's too dangerous to approach.

--
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"swag" wrote in
ups.com:

This is actually a maneuver that's demonstrated and practiced very
early in flight training, so I'm sure all pilots and student pilots
have experienced this. But your calculations are fairly correnct--a 2
minute turn won't cut it. It's usually demonstrated with a 60 degree
bank turn. I'm not sure of the timing, but i'd guess 30 sec or less.

You meant 45 degree bank. A 60 degree steep turn would require a parachute.

no it wouldn't

mike


You meant 45 degree bank. A 60 degree steep turn would require a
parachute.

mike regish writes:

no it wouldn't

If it's exactly 60 degrees, it wouldn't. Beyond 60 degrees, however, a
parachute is required. See FAR 91.307(c)(1).

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we weren't talking about beyond 60 degrees.

mike

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

no it wouldn't

If it's exactly 60 degrees, it wouldn't. Beyond 60 degrees, however, a
parachute is required. See FAR 91.307(c)(1).

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swag writes:

This is actually a maneuver that's demonstrated and practiced very
early in flight training, so I'm sure all pilots and student pilots
have experienced this. But your calculations are fairly correnct--a 2
minute turn won't cut it. It's usually demonstrated with a 60 degree
bank turn. I'm not sure of the timing, but i'd guess 30 sec or less.

Don't you have to descend to catch the wake? Downwash should be moving
downward at a few knots and IIRC the vortices do as well, so after two minutes
at, say, 12 knots, the turbulence would be almost 2500 feet below you, if you
are staying at altitude. I don't see how you could run into it.

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In rec.aviation.piloting Mxsmanic wrote:
swag writes:

This is actually a maneuver that's demonstrated and practiced very
early in flight training, so I'm sure all pilots and student pilots
have experienced this. But your calculations are fairly correnct--a 2
minute turn won't cut it. It's usually demonstrated with a 60 degree
bank turn. I'm not sure of the timing, but i'd guess 30 sec or less.

Don't you have to descend to catch the wake? Downwash should be moving
downward at a few knots and IIRC the vortices do as well, so after two minutes
at, say, 12 knots, the turbulence would be almost 2500 feet below you, if you
are staying at altitude. I don't see how you could run into it.

Real people in real airplanes training to become real pilots do real
45 degree bank, constant altitude turns on a regular basis and run into
their real wake.

It is just another thing you don't understand because you have no
context.

--
Jim Pennino

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writes:

Real people in real airplanes training to become real pilots do real
45 degree bank, constant altitude turns on a regular basis and run into
their real wake.

My research indicates that this is not possible. The wake sinks at a rate
between 150 and 500 feet per minute (roughly). Thus, it would always be well
below the airplane by the time it closes its own circle, unless the airplane
is also descending.

I've seen reports of pilots descending in a 360-degree turn and running into
their own wakes. If they can descend and encounter their own wake, then they
cannot remain at the same altitude and encounter it. It cannot be in two
places at once.

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