How to tell my instructor to increase glidespeed with headwind?

[Nik]

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

[Tobias Schnell]

On 1 Nov 2006 15:22:16 -0800, "Nik" > wrote:

>Do you guys have any ideas

Yes: Run, don't walk away from that instructor.

Tobias

[mike regish]

One simplified way would be to say you want to spend less time in the
headwind. Oversimplified, but it might at least get him to consider it.

Might use some simple math with convenient figures to prove it to him.

Best glide isn't in the books because it varies with weight and, as you can
see, wind conditions.

If you can't get it through to him, take the previous posters advice...run.

mike



"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
>

[Gary Drescher]

"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.
>...
> 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?

You might try pointing him to
http://www.av8n.com/how/htm/power.html#sec-wind-penetration.

Or you might try to convince him to let you fly it both ways and see which
way gets you further.

If that doesn't persuade him, you might decide do it his way when you fly
with him, and do it the right way at other times.

--Gary

[Larry Dighera]

On 1 Nov 2006 15:22:16 -0800, "Nik" > wrote in
om>:

>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.

Go to the Chief Pilot at the FBO, and ask him to explain it to your
CFI.

[[email protected]]

Remember what you're trying to do here: get ready for/pass a checkride!

Barry Schiff recently wrote an article about how he was being checked
out for a rental and he set his speed to 55kts during the engine-out
exercise because that is the "rate of least descent" for an airplane
with a best glide speed of 67 knots. He was trying to set the "least
descent" speed to give him time to choose an adequate landing site at
which time he would have set the nose for the best glide speed. While
Mr. Schiff was right, he got gigged on it and found himself having to
prove himself and educate an instructor instead of getting the sign-off
and an airplane for an afternoon.

He'd have been much better off, for his own purposes, to have been
selfish, done as the instructor expected and then rent the airplane. I
suspect you might want to think the same way since you're not in a
position of credibility as a student and this particular piece of
knowledge is probably not universally taught to instructors of powered
aircraft. I'm also betting you are correct and that the rules of
physics do not change just because you add 300 lbs of dead weight and a
motionless propeller to the front of the glider. 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?

In other words, for what you're trying to get done, please the
professor first. Engage in the debate after you get your license. Odds
are that you'd have the same tough sell in front of you if you attempt
the same argument during your checkride. You can prove you're right
later.

Does that seem sensible?

Humbly,

Greg Chapman



Nik wrote:

>
> Do you guys have any ideas on how I can really convince him? Any good
> sources?
>
> Thanks!
> -Nik

[Mxsmanic]

writes:

> Barry Schiff recently wrote an article about how he was being checked
> out for a rental and he set his speed to 55kts during the engine-out
> exercise because that is the "rate of least descent" for an airplane
> with a best glide speed of 67 knots. He was trying to set the "least
> descent" speed to give him time to choose an adequate landing site at
> which time he would have set the nose for the best glide speed. While
> Mr. Schiff was right, he got gigged on it and found himself having to
> prove himself and educate an instructor instead of getting the sign-off
> and an airplane for an afternoon.
>
> He'd have been much better off, for his own purposes, to have been
> selfish, done as the instructor expected and then rent the airplane. I
> suspect you might want to think the same way since you're not in a
> position of credibility as a student and this particular piece of
> knowledge is probably not universally taught to instructors of powered
> aircraft. I'm also betting you are correct and that the rules of
> physics do not change just because you add 300 lbs of dead weight and a
> motionless propeller to the front of the glider. 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?
>
> In other words, for what you're trying to get done, please the
> professor first. Engage in the debate after you get your license. Odds
> are that you'd have the same tough sell in front of you if you attempt
> the same argument during your checkride. You can prove you're right
> later.
>
> Does that seem sensible?

No, because the same instructor may misinform others who do not have
the benefit of other sources of information, and someone may be
injured or killed as a result of his misinformation.

Correct the instructor if he is wrong. If this creates an obstacle to
attaining your own objectives, find another instructor. But don't
just leave him to put other students in danger.

--
Transpose mxsmanic and gmail to reach me by e-mail.

[Darkwing]

"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

[Judah]

Mxsmanic > wrote in
:

> Correct the instructor if he is wrong. If this creates an obstacle to
> attaining your own objectives, find another instructor.

You're kidding, right?

[Peter Duniho]

> wrote in message
ups.com...
> [...]
> In other words, for what you're trying to get done, please the
> professor first. Engage in the debate after you get your license. Odds
> are that you'd have the same tough sell in front of you if you attempt
> the same argument during your checkride. You can prove you're right
> later.
>
> Does that seem sensible?

That advice makes some sense for someone in Schiff's position. I don't
agree that it makes sense for a student who is actually hiring his
instructor to teach him something.

In this case, the student knows the answer, understands the answer, and is
confident in that knowledge. But what if something else comes up in which
the instructor is *also* mistaken, and in which the instructor refuses to
consider the possibility that he's wrong? If it turns out in that situation
that Nik either doesn't know for sure what the right answer is, or doesn't
even have reason to suspect the instructor is wrong, then Nik will be at a
disadvantage, being taught by an instructor who should not be instructing in
the first place.

I have had situations with instructors in which I was only to fly with the
instructor once, for the purpose of showing some competence in an airplane
or type of flight or something like that and in which the instructor said or
did something that I disagreed with (and most of the time, it turned out I
was right :) ). In those situations, you're right...you just go with the
flow, and let the instructor have his way (assuming it's not a safety of
flight issue, of course...I had to terminate an IPC prematurely, because of
an instructor who was so bad, he was interfering with the safety of the
flight).

But for someone with whom you expect to have an on-going relationship, even
if for a few lessons but especially for a primary student, it's important to
a) resolve every single issue to the point of truthful consensus, and b) to
know that you can trust your instructor to not tell you something is
absolutely true when in fact it's known to be absolutely false.

I don't know whether the flight in question was a one-time thing, or is part
of on-going instruction that Nik is taking from the instructor, but in
absence of that knowledge, I think it's important to make sure that no one
thinks it's okay to just let an instructor say wrong things, especially if
one is doing more than just the one flight with that instructor.

Pete

[Kyle Boatright]

"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.

[Peter Duniho]

"Judah" > wrote in message
. ..
> Mxsmanic > wrote in
> :
>
>> Correct the instructor if he is wrong. If this creates an obstacle to
>> attaining your own objectives, find another instructor.
>
> You're kidding, right?

Obviously he's not. Mxsmanic has no qualms about "correcting" his
instructors even when they are already right. Clearly he would have no
problem correcting his instructor if he is wrong.

[Peter Duniho]

"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

[Mxsmanic]

Judah writes:

> You're kidding, right?

No.

--
Transpose mxsmanic and gmail to reach me by e-mail.

[Grumman-581[_1_]]

Peter Duniho wrote:
> Obviously he's not. Mxsmanic has no qualms about "correcting" his
> instructors even when they are already right. Clearly he would have no
> problem correcting his instructor if he is wrong.

Yeah, the ****in' troll would just say, "Well, that's not how it works
in MSFS, so you are wrong"...

[Jim Macklin]

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
|
|

[Judah]

"Peter Duniho" > wrote in news:12kihq1mi75qef1
@corp.supernews.com:

>>> Correct the instructor if he is wrong. If this creates an obstacle to
>>> attaining your own objectives, find another instructor.
>>
>> You're kidding, right?
>
> Obviously he's not. Mxsmanic has no qualms about "correcting" his
> instructors even when they are already right. Clearly he would have no
> problem correcting his instructor if he is wrong.

Yeah, but he's suggesting the OP go find a new instructor if correcting him
doesn't work.

So why does he refuse to do the same?

[Peter Duniho]

"Judah" > wrote in message
. ..
> Yeah, but he's suggesting the OP go find a new instructor if correcting
> him
> doesn't work.

I see what you mean.

> So why does he refuse to do the same?

Where else would he go?

An actual student pilot has the actual option of hiring a different
instructor. Our resident ignoramus is unlikely to find a more responsive,
more enthusiastic group of people to stir up than he's found here.
Obviously, his advice only applies to someone who has available to him a
better instructor.

Besides, it should not be all that surprising that, given his inability to
integrate information offered here into his knowledge, he is also unable to
integrate advice of his own that he offers. Just because he says it, that
doesn't mean he believes it, nor does it mean that even if he did believe,
he is capable of following the advice.

Pete

[Judah]

"Peter Duniho" > wrote in
:

> Where else would he go?
>
> An actual student pilot has the actual option of hiring a different
> instructor. Our resident ignoramus is unlikely to find a more
> responsive, more enthusiastic group of people to stir up than he's found
> here. Obviously, his advice only applies to someone who has available to
> him a better instructor.
>
> Besides, it should not be all that surprising that, given his inability
> to integrate information offered here into his knowledge, he is also
> unable to integrate advice of his own that he offers. Just because he
> says it, that doesn't mean he believes it, nor does it mean that even if
> he did believe, he is capable of following the advice.

It doesn't surprise me - after all it's impossible to fire an instructor
who doesn't charge you for his tutelage...

But then, the beatings he has taken from people calling him a troll (and
worse) would have certainly been enough punishment to seem like a cost.
It's been suggested that he try sim groups or even rec.aviation.student,
but he still refuses to go. Then again, for a guy who spends much of his
time in the alt.support.shyness group, he may have gotten so comfortable
with the regulars in this group, that it's easier for him to take the
beatings than it would be to try to engage new people on another forum.

One can never tell...

[Jay Beckman]

"Judah" > wrote in message
. ..
> "Peter Duniho" > wrote in
> :
>
>> Where else would he go?
>>
>> An actual student pilot has the actual option of hiring a different
>> instructor. Our resident ignoramus is unlikely to find a more
>> responsive, more enthusiastic group of people to stir up than he's found
>> here. Obviously, his advice only applies to someone who has available to
>> him a better instructor.
>>
>> Besides, it should not be all that surprising that, given his inability
>> to integrate information offered here into his knowledge, he is also
>> unable to integrate advice of his own that he offers. Just because he
>> says it, that doesn't mean he believes it, nor does it mean that even if
>> he did believe, he is capable of following the advice.
>
> It doesn't surprise me - after all it's impossible to fire an instructor
> who doesn't charge you for his tutelage...
>
> But then, the beatings he has taken from people calling him a troll (and
> worse) would have certainly been enough punishment to seem like a cost.
> It's been suggested that he try sim groups or even rec.aviation.student,
> but he still refuses to go. Then again, for a guy who spends much of his
> time in the alt.support.shyness group, he may have gotten so comfortable
> with the regulars in this group, that it's easier for him to take the
> beatings than it would be to try to engage new people on another forum.
>
> One can never tell...

Please do not, DO NOT, suggest he come over and spend more time in
r.a.student (he already crossposts there.)

Sure as hell, some student pilot will believe his increadible bull**** and
go get themselves killed.

Of course numbnuts would proably tell him he didn't die correctly because
that's not how it happens in MSFS.

Jay Beckman

[[email protected]]

Oh, I agree wholeheartedly and have been lucky enough to have an
instructor who would work that way with me.

However, and this is the biggie, the piece of knowledge we're talking
about...simply ain't taught if you're in a 172, for instance!!

If the POH has a published best glide speed, the instructor and the
examiner expect you to know that value and fly it. If you can explain a
variation, great! Go for it! You're still going to be asked to fly the
airplane to the POH spec. So perhaps my assumption is the fault in my
reasoning: I assumed an airplane where the POH publishes a value and,
as you examine the curriculum, it becomes apparent that the POH and the
candidates familiarity and observance of the data seem to be treated as
paramount. Check out the PPL knowledge guides for the written exam and
you'll note that this subject isn't even part of the curriculum!

I was once on a check out flight in a 172 over water next to Paine
field. Winds at altitude were gusting to speeds higher than the
published best glide. Instructor pulls the throttle, predictably, and I
react using the published data. He notes this and I observe to him, "We
aren't going to make that field upwind and 2 miles from us because
we're going backward."

"So what are you going to do?", he says.

"I'm going to trade altitude for speed to make that field as there are
no other clear areas reachable from this altitude including downwind.",
I reply.

"Fine, do it.", says he.

Same theory, same issue.

I think it would be good for Nik to chase that data down and teach his
instructor something he might need to know. But I don't think it will
do him much good if his examiner has a similar hole in knowledge. So
I'm suggesting should the situation repeat itself, he should
demonstrate competence in the expected manner and then consider a
conversation on the topic later. Should save him some trouble and he'll
still have useful knoweldge he can exercise should he really need it at
some point.

No instructor's knoweldge is perfectly complete, similarly, the same is
true for examiners, students or any other pilot. The situation of one
knowing something the other doesn't is normal. Attempting to share that
knowledge is good and commendable. But if doing so is going to cost
you, suppress it, get through the exercise, achieve your goal, teach
later.

That is, unless you enjoy arguing it...like we obviously do! ;)

Greg Chapman


Peter Duniho wrote:
> > wrote in message
> ups.com...
> > [...]
> > In other words, for what you're trying to get done, please the
> > professor first. Engage in the debate after you get your license. Odds
> > are that you'd have the same tough sell in front of you if you attempt
> > the same argument during your checkride. You can prove you're right
> > later.
> >
> > Does that seem sensible?
>
> That advice makes some sense for someone in Schiff's position. I don't
> agree that it makes sense for a student who is actually hiring his
> instructor to teach him something.
>
> In this case, the student knows the answer, understands the answer, and is
> confident in that knowledge. But what if something else comes up in which
> the instructor is *also* mistaken, and in which the instructor refuses to
> consider the possibility that he's wrong? If it turns out in that situation
> that Nik either doesn't know for sure what the right answer is, or doesn't
> even have reason to suspect the instructor is wrong, then Nik will be at a
> disadvantage, being taught by an instructor who should not be instructing in
> the first place.
>
> I have had situations with instructors in which I was only to fly with the
> instructor once, for the purpose of showing some competence in an airplane
> or type of flight or something like that and in which the instructor said or
> did something that I disagreed with (and most of the time, it turned out I
> was right :) ). In those situations, you're right...you just go with the
> flow, and let the instructor have his way (assuming it's not a safety of
> flight issue, of course...I had to terminate an IPC prematurely, because of
> an instructor who was so bad, he was interfering with the safety of the
> flight).
>
> But for someone with whom you expect to have an on-going relationship, even
> if for a few lessons but especially for a primary student, it's important to
> a) resolve every single issue to the point of truthful consensus, and b) to
> know that you can trust your instructor to not tell you something is
> absolutely true when in fact it's known to be absolutely false.
>
> I don't know whether the flight in question was a one-time thing, or is part
> of on-going instruction that Nik is taking from the instructor, but in
> absence of that knowledge, I think it's important to make sure that no one
> thinks it's okay to just let an instructor say wrong things, especially if
> one is doing more than just the one flight with that instructor.
>
> Pete

[[email protected]]

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.

[BT]

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
>

[BT]

I'll bet that instructor will get dizzy looking at that web page and stick
to his guns... even though he's carrying blanks.

BT

"Gary Drescher" > wrote in message
...
> "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.
>>...
>> 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?
>
> You might try pointing him to
> http://www.av8n.com/how/htm/power.html#sec-wind-penetration.
>
> Or you might try to convince him to let you fly it both ways and see which
> way gets you further.
>
> If that doesn't persuade him, you might decide do it his way when you fly
> with him, and do it the right way at other times.
>
> --Gary
>
>

[The Visitor]

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
>

[Andrew Sarangan[_1_]]

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.

[d&tm]

"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?
>
Without trying to second guess your instructor, I am not convinced from your
discussion that this represents a lack of knowledge on the part of your
instructor. He may simply be trying to keep things as simple as possible.
The idea of frequent practiced forced landings without power is to hopefully
give you the skills to do it without thinking in the event that it happens
to you in real life when you will likely be racked with shear terror.
Practicing at the published best glide speed , roughly gives you a constant
attitude "picture" that enables you to focus more outside the aircraft than
on the airspeed indicator. You could have a similar argument about weight
as the best glide speed will be significantly lower if you are flying solo
and especially if the reason for engine failure was no fuel! But are you
going to get out the calculator and calculate the weight corrected best
glide speed when the noise stops? Should an instructor tell you that flying
a Warrior solo would have a best glide speed closer to 65 kts than the
published 73kts? There is enough to learn already without over finessing
things too early in the learning. After all we know the learning really
starts after you get the license.
terry

[Dave Doe]

In article om>,
says...
> 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.

Yes, the greatest *distance* - if you *need* it. Otherwise, I think
he's right - fly at 65kts, and you get the longest time in the air
(something you're short of usually, when the fan dies).

But yep, you're right, *if* you need to get the distance to make the
field.

--
Duncan

[Mxsmanic]

Jay Beckman writes:

> Sure as hell, some student pilot will believe his increadible bull**** and
> go get themselves killed.

That is far less likely than a student pilot being killed by his
unquestioning acceptance of misinformation from a flight instructor
whom he has been told not to question.

It amazes me that students are being advised here to accept
misinformation and inaccuracy just for a piece of paper. However, it
does explain the misdeeds of some pilots. And it does resemble the
credentialism that afflicts society in general--a belief that the
paper is more important than what it putatively represents (because
restrictions address the paper, not the qualities it is supposed to
document).

--
Transpose mxsmanic and gmail to reach me by e-mail.

[Larry Dighera]

On 1 Nov 2006 16:16:10 -0800, wrote in
om>:

>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.

[Larry Dighera]

On Thu, 2 Nov 2006 22:02:09 +1300, Dave Doe > wrote in
>:

>fly at 65kts, and you get the longest time in the air

That is incorrect. Flying at best glide speed will give you the
maximum (no wind) distance over the ground just as Vy (velocity along
the Y axis: best rate of climb) does. Flying at minimum sink speed
will give you the most time before landing just as Vx (velocity along
the X axis: best angle of climb speed) provides the maximum height in
the shortest time (regardless of wind).

[Gary Drescher]

"Mxsmanic" > wrote in message
...
> It amazes me that students are being advised here to accept
> misinformation and inaccuracy just for a piece of paper.

They're not; your characterization is misinformed and inaccurate. The advice
was to make a substantial effort to persuade the instructor, and (if
unsuccessful) to show the instructor that yes, you are able to fly the
procedure as he wishes (which is not hazardous in a practice situation, and
does not require conceding error).

--Gary

[Judah]

Mxsmanic > wrote in
:

> That is far less likely than a student pilot being killed by his
> unquestioning acceptance of misinformation from a flight instructor
> whom he has been told not to question.
>
> It amazes me that students are being advised here to accept
> misinformation and inaccuracy just for a piece of paper. However, it
> does explain the misdeeds of some pilots. And it does resemble the
> credentialism that afflicts society in general--a belief that the
> paper is more important than what it putatively represents (because
> restrictions address the paper, not the qualities it is supposed to
> document).

Are you reading the same thread as everyone else here? Where did you come up
with this crap?

[Gary Drescher]

"d&tm" > wrote in message
...
> You could have a similar argument about weight
> as the best glide speed will be significantly lower if you are flying solo
> and especially if the reason for engine failure was no fuel! But are you
> going to get out the calculator and calculate the weight corrected best
> glide speed when the noise stops? Should an instructor tell you that
> flying
> a Warrior solo would have a best glide speed closer to 65 kts than the
> published 73kts?

Yes, students should definitely be taught which V-speeds need to be
weight-adjusted and which do not (and why). If you're 30% below gross
weight, the required 15% speed adjustment is nonnegligible. (Adjust Vs, Vs1,
Vl/d, Vx, Vy, Va. Do not adjust Vne, Vno, Vfe, Vle. See
http://www.av8n.com/how/htm/aoa.html#sec-ias-aoa for a detailed
explanation.)

But no, you don't do the calculation when an emergency arises. You should do
it in advance, as part of your W&B calculation. If you precompute the
adjustment factor, you can easily apply it in real time.

--Gary

[karl gruber[_1_]]

Back to the drawing board Dunc!

Karl
"Curator" N185KG


"Dave Doe" > wrote in message
z...
> In article om>,
> says...
>> 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.
>
> Yes, the greatest *distance* - if you *need* it. Otherwise, I think
> he's right - fly at 65kts, and you get the longest time in the air
> (something you're short of usually, when the fan dies).
>
> But yep, you're right, *if* you need to get the distance to make the
> field.
>
> --
> Duncan

[pgbnh]

To prove the point to your instructor.

Ask him/her to consider a headwind of 65kts. What are the chances of
reaching the field with a GS=0 ?? What are the chances if GS>0 ??
"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
>

[Brian[_1_]]

Ask him if 65kts is the best glide speed to get to the airport into a
65kt head wind.

I myself would use at least 90 as I am sure you would as well.

Brian
CFIIG/ASEL


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

[d&tm]

"Gary Drescher" > wrote in message
snip
> Yes, students should definitely be taught which V-speeds need to be
> weight-adjusted and which do not (and why). If you're 30% below gross
> weight, the required 15% speed adjustment is nonnegligible. (Adjust Vs,
Vs1,
> Vl/d, Vx, Vy, Va. Do not adjust Vne, Vno, Vfe, Vle. See
> http://www.av8n.com/how/htm/aoa.html#sec-ias-aoa for a detailed
> explanation.)
>
> But no, you don't do the calculation when an emergency arises. You should
do
> it in advance, as part of your W&B calculation. If you precompute the
> adjustment factor, you can easily apply it in real time.
>
Gary , I dont disagree with you . I do actually have a best glide speed wt
adjustment in my Excel wt and balance spreadhseet but as a student we were
not taught to adjust these speeds for weight, although we understood they
change with wt. and we certainly knew the non -negotiable ones like Vne and
Vfe etc. Again I figure their reason was to keep things simple, better
to overstimate than underestimate stall speeds. . although in hindsight it
had a lot to do with my early landing problems in the Warrior where it just
seemed to want to float for ever. I did actually post about this on this
group some years ago, because I thought the approach speeds I was being
taught were too high relative to the stall speed for the wt I was carrying
The 12 hour formal theoretical training I recieved for PPL was typical of
what seems to be happening with science education in our schools and
Australian society in general at the moment... a dumbing down to take maths
out of everything. But being a scientist myself I believe in the Lord
Kelvin theory. " if you cant explain what you know with numbers, your
knowledge is of a meagre and unsatisfactory kind" .. or something like that.
I have probably gone the other way now having set up spreadsheets to do my
Navigational wind triangle calculations ,great circle distance calculations,
calculating wt adusted stall speeds , wt and balance, turn physics ( radius
and time) , load and stall speed increase in turns , and my latest additon
is my energy balance to answer the question of how much ht I can actually
gain by turning speed to height. ( not much in a Warrior - 250 ft from
cruise to best glide speed after engine failure . but I havent allowed for
drag so it will be a bit less.). You know that Count character in Sesame
Street.. he's my hero.
terry

[Kev]

Judah wrote:
> Mxsmanic > wrote in
> :
> > It amazes me that students are being advised here to accept
> > misinformation and inaccuracy just for a piece of paper. [...]
>
> Are you reading the same thread as everyone else here? Where did you come up
> with this crap?

Eh? What he said is _exactly_ what the thread was about. I.e.
letting the instructor's misinformation slide just long enough to get
the license more easily, and then perhaps arguing the point later.

Is it the right thing to do? No. Does everyone have to do it?
Probably, unless you had one amazingly knowledgable CFI.

I suspect most people here have some story about a fact they knew was
true, but their instructor didn't believe it right away. Whether you
should change instructors or not depends on how dangerous or obvious
the error is, and whether he's willing to accept evidence to the
contrary. Inexperienced CFIs aren't going to know everything, but
they should know they don't.

Kev

[Dave Doe]

In article >,
says...
> On Thu, 2 Nov 2006 22:02:09 +1300, Dave Doe > wrote in
> >:
>
> >fly at 65kts, and you get the longest time in the air
>
> That is incorrect. Flying at best glide speed will give you the
> maximum (no wind) distance over the ground just as Vy (velocity along
> the Y axis: best rate of climb) does. Flying at minimum sink speed
> will give you the most time before landing just as Vx (velocity along
> the X axis: best angle of climb speed) provides the maximum height in
> the shortest time (regardless of wind).

If the best glide speed is 65kts in a C172, what is the best min. sink
speed?

--
Duncan

[Dave Doe]

In article >,
says...
> Back to the drawing board Dunc!

bloody top poster! :)

--
Duncan

[Judah]

"Kev" > wrote in
oups.com:

> Eh? What he said is _exactly_ what the thread was about. I.e.
> letting the instructor's misinformation slide just long enough to get
> the license more easily, and then perhaps arguing the point later.

That's not how I read it - "a student being killed by his unquestioning
acceptance of misinformation from a flight instructor" is not the same as
what you said.

None of the postings in this thread suggested that the student should ACCEPT
the instructor's misinformation as being accurate.

Manic's comment is the EXACT OPPOSITE of what was advised in the thread, and
I believe it was stated in an inflammatory manner in order to entice an
argument just like this one...

[Peter Duniho]

"Kev" > wrote in message
oups.com...
>> > It amazes me that students are being advised here to accept
>> > misinformation and inaccuracy just for a piece of paper. [...]
>>
>> Are you reading the same thread as everyone else here? Where did you come
>> up
>> with this crap?
>
> Eh? What he said is _exactly_ what the thread was about. I.e.
> letting the instructor's misinformation slide just long enough to get
> the license more easily, and then perhaps arguing the point later.

Only one person has suggested that. Characterizing the thread as being full
of such responses is absurd. Most correctly (IMHO) point out that not
pushing such a point is occasionally the right response, but generally is
not.

[Gary Drescher]

"Larry Dighera" > wrote in message
...
> On Thu, 2 Nov 2006 22:02:09 +1300, Dave Doe > wrote in
> >:
>
>>fly at 65kts, and you get the longest time in the air
>
> That is incorrect. Flying at best glide speed will give you the
> maximum (no wind) distance over the ground just as Vy (velocity along
> the Y axis: best rate of climb) does. Flying at minimum sink speed
> will give you the most time before landing just as Vx (velocity along
> the X axis: best angle of climb speed) provides the maximum height in
> the shortest time (regardless of wind).

Larry, you said that backwards. Best-glide speed is analogous to Vx: it
gives you the best (most positive) angle of flight. Minimum-sink speed is
analogous to Vy. It's Vy, not Vx, that gives you the maximum height in the
shortest time; Vx instead gives you the maximum height in the shortest
lateral distance. (And Vx and Vy do not refer to velocity along an x or y
axis.)

--Gary

[Al G[_1_]]

"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
>

Give your instructor the benefit of your background. As an instructor
for thirty years, I can say that i have learned a lot from my students. Some
of them had Mach 2+ experience and I was to solo them in a C-150.

Bet him a beer that you can outglide him under those circumstances.

Get him an introductory ride at a glider port...

Al G

[Don Byrer]

O
>No, because the same instructor may misinform others who do not have
>the benefit of other sources of information, and someone may be
>injured or killed as a result of his misinformation.
>
>Correct the instructor if he is wrong. If this creates an obstacle to
>attaining your own objectives, find another instructor. But don't
>just leave him to put other students in danger.


Go take the PPL or Glider written and maybe the FOI...then you can
make comments like that.
Don Byrer KJ5KB
Radar Tech & Smilin' Commercial Pilot Guy
Glider & CFI wannabe
kj5kb-at-hotmail.com

"I have slipped the surly bonds of earth; now if I can just land without bending the gear..."
"Watch out for those doves...<smack-smack-smack-smack...>"

[Andrew Gideon]

On Wed, 01 Nov 2006 19:35:01 -0700, Jay Beckman wrote:

> Of course numbnuts would proably tell him he didn't die correctly because
> that's not how it happens in MSFS.

<Heh> That's my long term goal: to fail to die correctly.

- Andrew

[Andrew Gideon]

On Wed, 01 Nov 2006 17:14:42 -0800, Peter Duniho wrote:

> That advice makes some sense for someone in Schiff's position.

I don't agree even there.

Others have already pointed out the benefit of educating the instructor.
In fact, if I recall that story correctly, the instructor did come away
with more knowledge than he'd before. That's a gain for all of us.

The reason I've not seen mentioned is that he [Schiff] could be sure about
something that does happen to be wrong. "Correcting" the CFI isn't just a
chance to teach the CFI something. It also confirms that the correction
is accurate.

Admittedly, after numerous corrections of the same misconception, I could
absolutely see the motivation on Schiff's part to just let it glide by
<laugh>. It's to his credit, I believe, that he hasn't.

- Andrew

[Larry Dighera]

On Thu, 2 Nov 2006 13:38:41 -0800, "Peter Duniho"
> wrote in
>:

> Most correctly (IMHO) point out that not pushing such a point is
>occasionally the right response, but generally is not.

I don't recall anyone advising Nik to contact a FSDO inspector, and
quizzing him about the FAA's point of view on this particular issue.
That should settle the argument, but I wouldn't be too hopeful.

[[email protected]]

Dave Doe wrote:
> In article >,
> says...
> > On Thu, 2 Nov 2006 22:02:09 +1300, Dave Doe > wrote in
> > >:
> >
> > >fly at 65kts, and you get the longest time in the air
> >
> > That is incorrect. Flying at best glide speed will give you the
> > maximum (no wind) distance over the ground just as Vy (velocity along
> > the Y axis: best rate of climb) does. Flying at minimum sink speed
> > will give you the most time before landing just as Vx (velocity along
> > the X axis: best angle of climb speed) provides the maximum height in
> > the shortest time (regardless of wind).
>
> If the best glide speed is 65kts in a C172, what is the best min. sink
> speed?

According to Kerschner, best glide speed (for distance) will be
around 1.3 Vs and minimum sink speed will be around 1.1 Vs. If the
airplane stalls clean at 50 kt, the minimum sink will be 55 kt and best
glide 65 kt.
But pay attention to the calibrated/indicated airspeed chart in
the POH. Airspeed indications are usually off quite a bit near the
stall.
One could go to altitude and do some gliding at various
stabilized airspeeds and find the one with the lowest rate of descent
on the VSI.

Dan

[karl gruber[_1_]]

"Larry Dighera" > wrote in message
...
> On Thu, 2 Nov 2006 13:38:41 -0800, "Peter Duniho"
> > wrote in
> >:
>
>> Most correctly (IMHO) point out that not pushing such a point is
>>occasionally the right response, but generally is not.
>
> I don't recall anyone advising Nik to contact a FSDO inspector, and
> quizzing him about the FAA's point of view on this particular issue.
> That should settle the argument, but I wouldn't be too hopeful.
>

What would the average FSDO insector possibly know about a FLYING issue?

Karl
"Curator" N185KG
40 check rides with the FAA

[mike regish]

I must be reading the same crap, because that's exactly what I've seen in a
number of replies.

mike

"Judah" > wrote in message
. ..
>
> Are you reading the same thread as everyone else here? Where did you come
> up
> with this crap?

[Mxsmanic]

Judah writes:

> None of the postings in this thread suggested that the student should ACCEPT
> the instructor's misinformation as being accurate.

Saying nothing about it is accepting it. And when the instructor's
misinformation is passed on to another student who doesn't have the
benefit of other independent sources of correct information, it is
taken as gospel, and sometimes bad things happen. My conscience would
not allow me to do that, but some people don't have much of a
conscience.

--
Transpose mxsmanic and gmail to reach me by e-mail.

[Mxsmanic]

Don Byrer writes:

> Go take the PPL or Glider written and maybe the FOI...then you can
> make comments like that.

I can make that comment without any exam of any kind. It's a question
of ethics, morals, and conscience, not acquired knowledge. Hurting
other people isn't good in my book. But not everyone uses the same
book.

--
Transpose mxsmanic and gmail to reach me by e-mail.

[Peter Duniho]

"Andrew Gideon" > wrote in message
...
> On Wed, 01 Nov 2006 17:14:42 -0800, Peter Duniho wrote:
>
>> That advice makes some sense for someone in Schiff's position.
>
> I don't agree even there.

I doubt that's true. My point isn't that one just never revists the issue.
It's that in mid-flight, getting into an argument with someone about
something that's not directly related to the safety of the flight isn't
worthwhile.

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

[zatatime]

On Wed, 01 Nov 2006 23:53:05 GMT, Larry Dighera >
wrote:

>Go to the Chief Pilot at the FBO, and ask him to explain it to your
>CFI.


Hey, I like this idea!

Then go find another instructor.

z

[mike regish]

That's wrong, too. Flying at minimum sink will get you the longest time in
the air-like you'd want if you had a tailwind and needed the distance.
Minimum sink is slower than best glide.

mike

----- Original Message -----
From: "Dave Doe" >
Newsgroups: rec.aviation.piloting
Sent: Thursday, November 02, 2006 4:02 AM
Subject: Re: How to tell my instructor to increase glidespeed with headwind?


>
> Yes, the greatest *distance* - if you *need* it. Otherwise, I think
> he's right - fly at 65kts, and you get the longest time in the air
> (something you're short of usually, when the fan dies).
>
> But yep, you're right, *if* you need to get the distance to make the
> field.
>
> --
> Duncan

[Judah]

Mxsmanic > wrote in
:

> Judah writes:
>
>> None of the postings in this thread suggested that the student should
>> ACCEPT the instructor's misinformation as being accurate.
>
> Saying nothing about it is accepting it. And when the instructor's

From the original post:

> 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.

So he had already told the instructor he was wrong, and had not accepted the
instructor's misinformation.

[Larry Dighera]

On Thu, 2 Nov 2006 16:49:24 -0800, "karl gruber"
> wrote in >:

>
>"Larry Dighera" > wrote in message
...
>> On Thu, 2 Nov 2006 13:38:41 -0800, "Peter Duniho"
>> > wrote in
>> >:
>>
>>> Most correctly (IMHO) point out that not pushing such a point is
>>>occasionally the right response, but generally is not.
>>
>> I don't recall anyone advising Nik to contact a FSDO inspector, and
>> quizzing him about the FAA's point of view on this particular issue.
>> That should settle the argument, but I wouldn't be too hopeful.
>>
>
>What would the average FSDO insector possibly know about a FLYING issue?
>

Right. It might be more appropriate for Nic to contact the Designated
Examiner he intends to use, and quiz him for what he expects to see.

[Gary Drescher]

"T o d d P a t t i s t" > wrote in message
...
> "Gary Drescher" > wrote:
>>Best-glide speed is analogous to Vx: it
>>gives you the best (most positive) angle of flight. Minimum-sink speed is
>>analogous to Vy. It's Vy, not Vx, that gives you the maximum height in the
>>shortest time; Vx instead gives you the maximum height in the shortest
>>lateral distance.
>
> These relationships and analogies between min sink/best
> glide and Vx/Vy are always giving trouble. On the one hand,
> the comment above is right. Min sink and Vy both relate to
> climb/descent rates and excess power. Best glide and Vx
> both relate to angle of climb/descent, excess thrust and
> force.
>
> On the other hand, Vy is faster than Vx while Vy's
> correlated speed, min sink, is SLOWER than Vx's correlated
> speed, best glide.
>
> The difference is that min sink/best glide numbers relate
> only to airframe/airfoil performance while the Vx/Vy numbers
> add in the engine/propeller performance.

John Denker's explanation of the relations among Vx, Vy, min sink, and best
glide is the clearest I've encountered:
http://www.av8n.com/how/htm/power.html#sec-power-curve. Sec. 7.5.4 makes it
geometrically evident at a glance why Vy is greater than Vx but min sink is
less than best glide. Lowering the power curve from full power to zero power
shifts the point at which a line through the origin is tangent to the curve:
the tangent point is prior to the maximum point when the curve is high, but
after the maximum point when the curve is low. (Engine/prop performance
factors mean that the curve gets deformed somewhat as it's raised and
lowered [sec. 7.5.6], but that's a secondary factor.)

--Gary

[d&tm]

"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?


I found this link very helpful
http://www.auf.asn.au/emergencies/aircraft.html
terry

[d&tm]

"T o d d P a t t i s t" > wrote in message
...
> "mike regish" > wrote:
> >That's wrong, too. Flying at minimum sink will get you the longest time
in
> >the air-like you'd want if you had a tailwind and needed the distance.
> >Minimum sink is slower than best glide.
>
> You only fly at min sink for better distance when the
> tailwind is infinite. At any slower tailwind speed, you fly
> somewhat faster than min sink, but not as fast as best
> glide. Generally, if you turn downwind, you will be able to
> glide quite far and will have more fields you can reach, so
> getting the absolute maximum distance is less important than
> picking a good field and setting up a good pattern.
>
I could think of other reasons to fly minimum sink
1. More time to get the engine restarted
2. If flying over tiger country .. you get to live longer :>)
terry

[d&tm]

> wrote in message
ups.com...
>
> Dave Doe wrote:
> > In article >,
> > says...
> > > On Thu, 2 Nov 2006 22:02:09 +1300, Dave Doe > wrote in
> > > >:
> > >
> > > >fly at 65kts, and you get the longest time in the air
> > >
> > > That is incorrect. Flying at best glide speed will give you the
> > > maximum (no wind) distance over the ground just as Vy (velocity along
> > > the Y axis: best rate of climb) does. Flying at minimum sink speed
> > > will give you the most time before landing just as Vx (velocity along
> > > the X axis: best angle of climb speed) provides the maximum height in
> > > the shortest time (regardless of wind).
> >
> > If the best glide speed is 65kts in a C172, what is the best min. sink
> > speed?
>
> According to Kerschner, best glide speed (for distance) will be
> around 1.3 Vs and minimum sink speed will be around 1.1 Vs. If the
> airplane stalls clean at 50 kt, the minimum sink will be 55 kt and best
> glide 65 kt.
> But pay attention to the calibrated/indicated airspeed chart in
> the POH. Airspeed indications are usually off quite a bit near the
> stall.
> One could go to altitude and do some gliding at various
> stabilized airspeeds and find the one with the lowest rate of descent
> on the VSI.
>
Another rule of thumb is lowest sink speed is 90% of best glide speed. So
for the C172
best glide 65 best sink 58.5
terry

[Grumman-581[_1_]]

d&tm wrote:
> I could think of other reasons to fly minimum sink
> 1. More time to get the engine restarted
> 2. If flying over tiger country .. you get to live longer :>)

Flying over water, but so far away from land or any visible ships that
where you fly to will not really made a difference... What you need is
more time in the air to broadcast a Mayday for as long as possible...
And possibly more time to get your survival gear ready...

[Andrew Gideon]

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

[Larry Dighera]

On 3 Nov 2006 10:45:01 -0600, T o d d P a t t i s t
> wrote in
>:


>You only fly at min sink for better distance when the
>tailwind is infinite. At any slower tailwind speed, you fly
>somewhat faster than min sink, but not as fast as best
>glide.

http://www.glidingmagazine.com/CommDetail.asp?ParentId=178&RootId=0
McCready theory usually uses the formula

Sink rate = a x V^2 - b x V + c

where a, b and c are the parameters to fit. This formula has the
advantage that it makes the math much nicer, but the disadvantage that
it is just plain wrong, in the sense that it says that sink rate
increases like V^2 at high speeds, which it doesn't - it increases
like V^3, which is much faster!

[Dave Doe]

In article >,
says...
>
> > wrote in message
> ups.com...
> >
> > Dave Doe wrote:
> > > In article >,
> > > says...
> > > > On Thu, 2 Nov 2006 22:02:09 +1300, Dave Doe > wrote in
> > > > >:
> > > >
> > > > >fly at 65kts, and you get the longest time in the air
> > > >
> > > > That is incorrect. Flying at best glide speed will give you the
> > > > maximum (no wind) distance over the ground just as Vy (velocity along
> > > > the Y axis: best rate of climb) does. Flying at minimum sink speed
> > > > will give you the most time before landing just as Vx (velocity along
> > > > the X axis: best angle of climb speed) provides the maximum height in
> > > > the shortest time (regardless of wind).
> > >
> > > If the best glide speed is 65kts in a C172, what is the best min. sink
> > > speed?
> >
> > According to Kerschner, best glide speed (for distance) will be
> > around 1.3 Vs and minimum sink speed will be around 1.1 Vs. If the
> > airplane stalls clean at 50 kt, the minimum sink will be 55 kt and best
> > glide 65 kt.
> > But pay attention to the calibrated/indicated airspeed chart in
> > the POH. Airspeed indications are usually off quite a bit near the
> > stall.
> > One could go to altitude and do some gliding at various
> > stabilized airspeeds and find the one with the lowest rate of descent
> > on the VSI.
> >
> Another rule of thumb is lowest sink speed is 90% of best glide speed. So
> for the C172
> best glide 65 best sink 58.5
> terry

Thanks guys.

--
Duncan