How to tell my instructor to increase glidespeed with headwind?

On Thu, 02 Nov 2006 19:40:16 -0800, Peter Duniho wrote:

You seem to be disagreeing with something else, and not something I
actually wrote.

Okay. I'd missed that you qualified it with "during the flight".

- Andrew

On 1 Nov 2006 16:16:10 -0800, wrote in
. com:

But, what is it you're
trying to do? Prove something he doesn't know? Or are you more
interested in proving your competence by his standards?

I understand what you are saying, but to admire the nude emperor's new
suit of clothes, and thus compromise one's personal standard of truth
and honesty, is repugnant at best, and mendacious in fact. Personally,
I would unable to do that.

"Nik" wrote in message
ups.com...
Ok, my instructor did a simulated engine failure in the pattern; winds
were around 20kts in the air and 13kts on the ground. Did everything
perfectly; however after we took off again, he told me to maintain 65
kts next time, and I totally disagreed.
The manual says 65 kts for best glide speed; however that is in calm
air. As a glider person, I know adding about 1/2 the headwind component
will give the greatest distance.
After the flight I pulled up the Glider Flying handbook online and it
says:

"...it is apparent that flying a faster airspeed as the headwind
increases will result in the greatest distance over the
ground. If this is done for the polar curves from many
gliders, a general rule of thumb is found, namely, add
half the headwind component to the best L/D for the
maximum distance."

But even after telling him that he said that doesn't apply to power
planes, also saying that manuals never give best glide, and there has
to be a reason for that.

Do you guys have any ideas on how I can really convince him? Any good
sources?

Thanks!
-Nik


It has been a while since this happened, but my Instructor when I was going
for my PP-ASEL told me 70 was best glide in the C172 but I knew the manual
said 65, I showed him it one day and he said he was wrong and glad I pointed
it out. So if you show him info "from a higher power" he will listen.

--------------------------------------------------
DW

"Darkwing" theducksmailATyahoo.com wrote in message
...
It has been a while since this happened, but my Instructor when I was
going for my PP-ASEL told me 70 was best glide in the C172 but I knew the
manual said 65, I showed him it one day and he said he was wrong and glad
I pointed it out. So if you show him info "from a higher power" he will
listen.

The problem here is that the POH for the Cessna 172 does not (as far as I
recall) discuss adjusting best glide airspeed for wind. This isn't a
question of using the wrong data for the airplane, but applying the
published data incorrectly.

There are other "higher powers" to refer to, but in this case, Nik already
tried showing the instructor one (the "Glider Flying Handbook"...an FAA
publication, I assume?), and the instructor didn't accept that as a valid
reference.

Pete

Ask the instructor what IAS should be flown with a wind that
is 50 knots? Then do a wind triangle and try the same
calculation with higher IAS. Personally I would fly
zero-wind at best glide plus 5 knots, that allows some
recovery if there is a need.

Also, ask the instructor to explain his theory of the best
glide with a dead engine and how that compares to a glider.
Also ask why gliders often use partial speed brakes on
approach?



"Peter Duniho" wrote in
message ...
| "Darkwing" theducksmailATyahoo.com wrote in message
| ...
| It has been a while since this happened, but my
Instructor when I was
| going for my PP-ASEL told me 70 was best glide in the
C172 but I knew the
| manual said 65, I showed him it one day and he said he
was wrong and glad
| I pointed it out. So if you show him info "from a higher
power" he will
| listen.
|
| The problem here is that the POH for the Cessna 172 does
not (as far as I
| recall) discuss adjusting best glide airspeed for wind.
This isn't a
| question of using the wrong data for the airplane, but
applying the
| published data incorrectly.
|
| There are other "higher powers" to refer to, but in this
case, Nik already
| tried showing the instructor one (the "Glider Flying
Handbook"...an FAA
| publication, I assume?), and the instructor didn't accept
that as a valid
| reference.
|
| Pete
|
|

"Nik" wrote in message
ups.com...
Ok, my instructor did a simulated engine failure in the pattern; winds
were around 20kts in the air and 13kts on the ground. Did everything
perfectly; however after we took off again, he told me to maintain 65
kts next time, and I totally disagreed.
The manual says 65 kts for best glide speed; however that is in calm
air. As a glider person, I know adding about 1/2 the headwind component
will give the greatest distance.
After the flight I pulled up the Glider Flying handbook online and it
says:

"...it is apparent that flying a faster airspeed as the headwind
increases will result in the greatest distance over the
ground. If this is done for the polar curves from many
gliders, a general rule of thumb is found, namely, add
half the headwind component to the best L/D for the
maximum distance."

But even after telling him that he said that doesn't apply to power
planes, also saying that manuals never give best glide, and there has
to be a reason for that.

Do you guys have any ideas on how I can really convince him? Any good
sources?

Thanks!
-Nik

Point out what happens if there is a 65 kt headwind. I.E. you just descend
without any horizontal speed. So, in that case something over 65 knots
would give you more glide range. While that doesn't prove that adding half
the wind velocity is a good rule of thumb, it clearly demonstrates that
"best glide" isn't always the right answer.

Nik wrote:
Ok, my instructor did a simulated engine failure in the pattern; winds
were around 20kts in the air and 13kts on the ground. Did everything
perfectly; however after we took off again, he told me to maintain 65
kts next time, and I totally disagreed.
The manual says 65 kts for best glide speed; however that is in calm
air. As a glider person, I know adding about 1/2 the headwind component
will give the greatest distance.
After the flight I pulled up the Glider Flying handbook online and it
says:

"...it is apparent that flying a faster airspeed as the headwind
increases will result in the greatest distance over the
ground. If this is done for the polar curves from many
gliders, a general rule of thumb is found, namely, add
half the headwind component to the best L/D for the
maximum distance."

But even after telling him that he said that doesn't apply to power
planes, also saying that manuals never give best glide, and there has
to be a reason for that.

Do you guys have any ideas on how I can really convince him? Any good
sources?

Thanks!
-Nik

Once the engine quits, the power plane is a glider, albeit one with a
really sucky glide ratio. As someone else pointed out, ask the
instructor what the best glide speed is if there is a headwind that
equals the POH recommended glide speed.

This is just one area in which I have come to believe that pilots with
glider experience have an edge over power pilots. I truly believe that
glider pilots have to know a lot more about their airplanes,
micro-weather, etc.

Instructors are people. Sometimes they are wrong. Since they are in
something of an authority position, there is a tendency to defend an
idea. Attempting to teach them something can be a learning
experience--the student will gain some experience in diplomacy, and
might find out that HE is wrong himself. Usually, I've found that the
instructor and student are looking at two slightly different things,
and that continuing a rational conversation will iron things out.

If not, there are lots of instructors out there. Avoid getting bent
out of shape.

well.. glide speed adjustments into a headwind applies to every thing that
moves through the air.. just ask the birds. do the math.. what is his
effective L/d over the ground if he does not increase speed

and.. my New C-182T POD does give "best glide" speed.

"Nik" wrote in message
ups.com...
Ok, my instructor did a simulated engine failure in the pattern; winds
were around 20kts in the air and 13kts on the ground. Did everything
perfectly; however after we took off again, he told me to maintain 65
kts next time, and I totally disagreed.
The manual says 65 kts for best glide speed; however that is in calm
air. As a glider person, I know adding about 1/2 the headwind component
will give the greatest distance.
After the flight I pulled up the Glider Flying handbook online and it
says:

"...it is apparent that flying a faster airspeed as the headwind
increases will result in the greatest distance over the
ground. If this is done for the polar curves from many
gliders, a general rule of thumb is found, namely, add
half the headwind component to the best L/D for the
maximum distance."

But even after telling him that he said that doesn't apply to power
planes, also saying that manuals never give best glide, and there has
to be a reason for that.

Do you guys have any ideas on how I can really convince him? Any good
sources?

Thanks!
-Nik

That rule of thumb doesn't quite work, as the wing loading is different.
I would guess 4 to 6 knots but I've not the time for the maths right now.

Nik wrote:
Ok, my instructor did a simulated engine failure in the pattern; winds
were around 20kts in the air and 13kts on the ground. Did everything
perfectly; however after we took off again, he told me to maintain 65
kts next time, and I totally disagreed.
The manual says 65 kts for best glide speed; however that is in calm
air. As a glider person, I know adding about 1/2 the headwind component
will give the greatest distance.
After the flight I pulled up the Glider Flying handbook online and it
says:

"...it is apparent that flying a faster airspeed as the headwind
increases will result in the greatest distance over the
ground. If this is done for the polar curves from many
gliders, a general rule of thumb is found, namely, add
half the headwind component to the best L/D for the
maximum distance."

But even after telling him that he said that doesn't apply to power
planes, also saying that manuals never give best glide, and there has
to be a reason for that.

Do you guys have any ideas on how I can really convince him? Any good
sources?

Richard Collins.

Thanks!
-Nik

Nik wrote:
Ok, my instructor did a simulated engine failure in the pattern; winds
were around 20kts in the air and 13kts on the ground. Did everything
perfectly; however after we took off again, he told me to maintain 65
kts next time, and I totally disagreed.
The manual says 65 kts for best glide speed; however that is in calm
air. As a glider person, I know adding about 1/2 the headwind component
will give the greatest distance.
After the flight I pulled up the Glider Flying handbook online and it
says:

"...it is apparent that flying a faster airspeed as the headwind
increases will result in the greatest distance over the
ground. If this is done for the polar curves from many
gliders, a general rule of thumb is found, namely, add
half the headwind component to the best L/D for the
maximum distance."

But even after telling him that he said that doesn't apply to power
planes, also saying that manuals never give best glide, and there has
to be a reason for that.

Do you guys have any ideas on how I can really convince him? Any good
sources?

Thanks!
-Nik


Most airplane training books don't discuss this concept, and POH rarely
ever mention this. We are taught by a system that enforces the view
that we should follow the POH exactly and not improvise anything. So it
is not unreasonable that this instructor never gave much thought to
this concept until you challenged him. However, most intelligent people
will realize this as soon as you point it out. You owe him at least
that much. If he doesn't turn around, then you have to start wondering
what other uncorrected misconceptions that he is passing on to you.

Everyone makes and has misconceptions, but stubbornly holding on to
them in the face of opposing evidence is what distinguishes an
intellect from others.