How to tell my instructor to increase glidespeed with headwind?

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).

"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

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?

"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

Back to the drawing board Dunc!

Karl
"Curator" N185KG


"Dave Doe" wrote in message
z...
In article . com,
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

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 GS0 ??
"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

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

"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

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

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