Question to Mxmanic

On a bumpy day you wouldn't be able to tell the wake from the overall
turbulence.

On an otherwise smooth day you can.

It can be done, Tony.

mike

"Mxsmanic" wrote in message
...
writes:

You do a 360 and run into a bump when, and only when, you complete
the 360.

Or you run into bumps but only notice the one that you hit when you
complete
the 360.

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On Apr 14, 4:27 pm, "george" wrote:
I always maintained altitude and rate of turn in steep turns with the
end result being hitting my own slipstream.

As have we all on nice days, and students like to brag about it. Yet
Mx is correct, in theory we should not be able to do this.

I seem to recall recent magazine (web?) articles where the idea that
you can hit your own wake while actually holding altitude, should be
downplayed nowadays. You _have_ to descend a little bit to do so,
which means that, while you might be within the +/- 100' test
scenario, you are NOT holding the same exact altitude.

Hmm. Or else it means that the wake doesn't necessarily descend as
we're taught. On a warm clear day (which is when I've hit my own
wake), I betcha that the wake is being held upward a tiny bit by the
heat from the ground.

Cheers, Kev

I seem to recall recent magazine (web?) articles where the idea that
you can hit your own wake while actually holding altitude, should be
downplayed nowadays. You _have_ to descend a little bit to do so,

How tall is the wake?

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

You do a 360 and run into a bump when, and only when, you complete
the 360.

Or you run into bumps but only notice the one that you hit when you complete
the 360.

Yeah, sure.

The first time it happened to me was early in training when I was
very aware of every little bump or noise from the airplane.

As I was rolling out of the turn there was a ka-bump and my startled
reaction was a loud "What the hell was that?" which amused the
instuctor to no end.

Just because you have never experienced it and can't understand it
from your many hours of playing the Flight Simulator game doesn't
mean it doesn't exist.

It just means you don't know a whole lot about real flying or what
happens in a real airplane.

Have you ever done a short field take off in your Flight Simulator
Cessna with the springy gear and had the mains vibrate for a few
seconds shaking the airplane? It is disconserting as hell for a
low time student ready to chop power and abort take off at any
sign of a problem. Again, the instructor was amused.

--
Jim Pennino

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On Apr 16, 9:41 am, Jose wrote:
I seem to recall recent magazine (web?) articles where the idea that
you can hit your own wake while actually holding altitude, should be
downplayed nowadays. You _have_ to descend a little bit to do so,

How tall is the wake?

Good point. Still, using the calculator at:

http://www.csgnetwork.com/aircraftturninfocalc.html

It's going to take about 30 seconds to fly a 360 steep turn at
100kts. My wake _should_ descend about 150' during that time (300
fpm). I can't imagine a C172 wake being tall enough to stay in my
way unless something else is ocurring (me descending, or the wake
staying up).

Would love to hear a decent explanation. Kev

My wake _should_ descend about 150' during that time (300
fpm). I can't imagine a C172 wake being tall enough to stay in my
way...

I can. 150 feet is not tall at all for a wake. Remember, the air
around the wake is also being dragged by the wake vortex.

You're going to bump into something.

Jose
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In rec.aviation.piloting Kev wrote:
On Apr 16, 9:41 am, Jose wrote:
I seem to recall recent magazine (web?) articles where the idea that
you can hit your own wake while actually holding altitude, should be
downplayed nowadays. You _have_ to descend a little bit to do so,

How tall is the wake?

Good point. Still, using the calculator at:

http://www.csgnetwork.com/aircraftturninfocalc.html

It's going to take about 30 seconds to fly a 360 steep turn at
100kts. My wake _should_ descend about 150' during that time (300
fpm). I can't imagine a C172 wake being tall enough to stay in my
way unless something else is ocurring (me descending, or the wake
staying up).

Would love to hear a decent explanation. Kev

Upon what do you base the assumption your wake should decend 150'?

I have never heard of any study of the wake properties of GA aircraft
and the wake of a C172 is very different than the wake of a 747 so
to extrapolate from studies of transport catagory wakes is pointless.

--
Jim Pennino

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Kev writes:

On a warm clear day (which is when I've hit my own
wake), I betcha that the wake is being held upward a tiny bit by the
heat from the ground.

Then you must be descending through the rising column of air.

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Jose writes:

How tall is the wake?

The downwash is at least equal in height to the total wingspan of the
aircraft. Downwash is a large mass of air moving slowly. Still, you should
not be hitting your own wake in a 360-degree turn unless you are descending to
catch it. Oddly enough, if you are descending, the wake moves more slowly
(because you are generating less lift).

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Jose writes:

I can. 150 feet is not tall at all for a wake.

It's extremely tall for a small aircraft. The wake would probably be about 50
feet high.

Remember, the air around the wake is also being dragged by the wake vortex.

But at very slow speed. Even the downwash itself is moving slowly, only a few
knots. Any of the winds that one often encounters at altitude would be enough
to rapidly disperse it.

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