Question to Mxmanic

Mxsmanic wrote in
:

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.

I'm not a physicist, but I suspect your calculations are missing several
factors, including (but not limited to) some that I can point out:

1) At a 45 degree bank, the wings are not actually pointed directly down.

2) In the typical trainer plane flying 100 knots, a 45 degree bank turn
will take far less than 2 minutes to go 360 degrees.

3) Wind can blow the wake in any number of directions, including up, and
including into the path of the 360 degree turn.

The bottom line is that the Practical Test Standards call for pilots to
perform a manuever called a Steep Turn of 360 degrees at a bank angle of 45
degrees. Every certificated pilot practices this, and demonstrates it to an
examiner, and frequently demonstrates it again during his or her Biannual
Flight Review.

Do you think it is more likely that the pilots on this newsgroup who
express that they have flown through their own wake while performing this
manuever are just lying to you?

Or perhaps you have miscalculated or omitted something from your
calculations.

Judah writes:

1) At a 45 degree bank, the wings are not actually pointed directly down.

Even at a 45-degree bank, the wake will still descend (and it will also move
outward, making it hard to catch as well).

3) Wind can blow the wake in any number of directions, including up, and
including into the path of the 360 degree turn.

But it will blow the aircraft in the same direction. The wake will still
descend relative to the aircraft.

Do you think it is more likely that the pilots on this newsgroup who
express that they have flown through their own wake while performing this
manuever are just lying to you?

No. I think they just don't realize that they were descending when they
caught their own wakes.

Or perhaps you have miscalculated or omitted something from your
calculations.

I didn't calculate much; I just looked things up. Without exception, every
source says that the wake descends. And it has to, since that's the only way
to keep the aircraft flying.

--
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Mxsmanic wrote in
:

Even at a 45-degree bank, the wake will still descend (and it will also
move outward, making it hard to catch as well).

What is the wingspan of the aircraft?

But it will blow the aircraft in the same direction. The wake will
still descend relative to the aircraft.

The aircraft is powered. It need not follow the wind alone.

No. I think they just don't realize that they were descending when they
caught their own wakes.

Altimeters make this less likely than you might believe. Perhaps you are the
one that doesn't realize something. As you admit below, you didn't put much
thought into your determination.

I didn't calculate much; I just looked things up. Without exception,
every source says that the wake descends. And it has to, since that's
the only way to keep the aircraft flying.

Judah writes:

What is the wingspan of the aircraft?

The wingspan shouldn't matter.

Altimeters make this less likely than you might believe. Perhaps you are the
one that doesn't realize something. As you admit below, you didn't put much
thought into your determination.

To convince me, I need an explanation of why wakes descend universally except
by some magic exception when someone is doing a 360-degree turn.

--
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Mxsmanic,

To convince me,


What, exactly, do you think this group could possibly gain by even
trying to convince you?

--
Thomas Borchert (EDDH)

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

What is the wingspan of the aircraft?

The wingspan shouldn't matter.

Altimeters make this less likely than you might believe. Perhaps you are the
one that doesn't realize something. As you admit below, you didn't put much
thought into your determination.

To convince me, I need an explanation of why wakes descend universally except
by some magic exception when someone is doing a 360-degree turn.

Why in the world would anyone bother to do anything other than to tell
you it has, in fact, happened to them?

If you feel some need to be convinced you are full of crap, turn off the
computer, get off your ass, and go fly in a real airplane and observe
it for yourself.

--
Jim Pennino

Remove .spam.sux to reply.

Mxsmanic wrote in
:

The wingspan shouldn't matter.

I haven't studied geometry in a long time, but simple geometry would dictate
that at a 45 degree angle, vortices generated by the higher wing would
naturally need to fall some distance before they could not be intercepted by
the lower wing.

To convince me, I need an explanation of why wakes descend universally
except by some magic exception when someone is doing a 360-degree turn.

I am not able to explain to you the scientific principles behind why I have
observed what I have observed. I can only tell you that I have observed it,
as have numerous other pilots, and the fact that you don't believe me is your
problem, not mine.

Judah, one of his problems is that he fixates on insufficient
information, and then gets frustrated when his assumptions are
incorrect. Obviously, MX can only concieve of downwash generated by the
wings as they create lift. Apparently, he can't concieve of the UPWASH
created by the tail surfaces pushing DOWN, nor the potential for
interaction between the two, or other turbulence that may be created in
the air mass merely because a large object is plowing through it at a
high rate of speed.

Rip

"Rip" wrote in message
et...
Judah, one of his problems is that he fixates on insufficient information,
and then gets frustrated when his assumptions are incorrect. Obviously, MX
can only concieve of downwash generated by the wings as they create lift.
Apparently, he can't concieve of the UPWASH created by the tail surfaces
pushing DOWN, nor the potential for interaction between the two, or other
turbulence that may be created in the air mass merely because a large
object is plowing through it at a high rate of speed.

Rip

Or that the wake of a Cessna 150 might not sink as fast as the wake of a
fully loaded 747...

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

Rip wrote in news:AIvUh.10078$YL5.3718
@newssvr29.news.prodigy.net:

Judah, one of his problems is that he fixates on insufficient
information, and then gets frustrated when his assumptions are
incorrect.

He doesn't get frustrated. He simply denies the possibility that he is wrong
by changing the scope of the original question so he can claim he was right
all along. His ego simply won't allow him to be wrong.

It's like a disease.

Obviously, MX can only concieve of downwash generated by the
wings as they create lift. Apparently, he can't concieve of the UPWASH
created by the tail surfaces pushing DOWN, nor the potential for
interaction between the two, or other turbulence that may be created in
the air mass merely because a large object is plowing through it at a
high rate of speed.

I didn't think of this myself, but it certainly makes sense to me. I suspect
it will make sense to MX too, and then he will try to convince us all that
this doesn't qualify as Wake Turbulence or that he was only referring to
downwash from the wings to begin with or some other change in the scope of
his comments to make him right (at least in his own mind).