tow rope brake practice crash, what can we learn...

On Jul 12, 3:11*am, Tony V wrote:
snip

Forgot point number 3. You can't just point the nose down and start your
turn back to the airport. You have to wait until you have enough
airspeed to pull that off. Something that gets drilled into every winch
student (I hope).

Interesting. In my own glider a typical tow speed is somewhat above
best l/d speed so the first things would be to lift the nose slightly
and trim for approach speed. It's a typical 15m unflapped glass
glider so 60 knots is fine, typical tow speeds are 70-80 knots.

On Jul 13, 3:01*am, Cats wrote:
On Jul 12, 3:11*am, Tony V wrote:
snip



Forgot point number 3. You can't just point the nose down and start your
turn back to the airport. You have to wait until you have enough
airspeed to pull that off. Something that gets drilled into every winch
student (I hope).

Interesting. *In my own glider a typical tow speed is somewhat above
best l/d speed so the first things would be to lift the nose slightly
and trim for approach speed. *It's a typical 15m unflapped glass
glider so 60 knots is fine, typical tow speeds are 70-80 knots.

Yes, tow speeds are usually greater than approach speeds.....this
means simply that you have "energy" in speed....

In practice at altitude, we often make a 180 degree turn off of tow,
with no loss of altitude.....and just a slight loss of speed...as you
say, staying at or above best l/d speed..We can even do a gently
climbing turn off tow, at altitude, and gain maybe 100' while slowing
from tow speed to best l/d or even slow to min sink. But I would not
recommend this near the ground.

Another point to consider, the faster the speed in a turn, the larger
the radius of turn......there may be some benefit to a slightly slower
turn (but not too slow).

We know that angle of attack is the concern in stall avoidance....any
stall spin accident off of low rope break has to have had too much
angle of attack, one way or another....This means too much stick back
pressure....This is why I like to see an obvious stick forward and
nose pitch down reaction upon rope break.....also smooth control
inputs....

But speed (suffecient speed) is also necessary for good control,
handling, dealing with gusts etc.

I think you did miss one slight concept however, that when we are on
tow, our attitude is slightly more nose up at a given speed, than what
the nose attidude would be at the same speed while not on
tow.......thrust is the variable ....

Most gliders tow with a slight nose up attitude....So if you release
from tow, and maintain the same nose attitude, or even raise the nose
further as you suggest, I think you will find a rapid decrease in
airspeed...not to mention that the thought of raising the nose while
turning, while low, just sends shivers down my spine.....

On a rope break, I instruct my students to establish the same nose
down attitude that would be used in a "normal" pattern. I find that
making the turn seems to work out well for most pilots, but the
decision making after the completion of the 180 is often
lacking......they do not recognize the problems associated with a down
wind landing...(use of spoiler and need for slip for instance)

Cookie

" wrote:

On Jul 13, 3:01*am, Cats wrote:
On Jul 12, 3:11*am, Tony V wrote:
snip

Another point to consider, the faster the speed in a turn, the larger
the radius of turn......there may be some benefit to a slightly slower
turn (but not too slow).

Have you ever considered a steeply banked side slipping turn ?
You may have a high rate of descent, but the radius of turn is so
small that the duration is very short, making the height loss small,
and you do not need to increase airspeed to do it.


We know that angle of attack is the concern in stall avoidance....any
stall spin accident off of low rope break has to have had too much
angle of attack, one way or another....This means too much stick back
pressure....This is why I like to see an obvious stick forward and
nose pitch down reaction upon rope break.....also smooth control
inputs....

Gilbert

Have you ever considered a steeply banked side slipping turn ?
You may have a high rate of descent, but the radius of turn is so
small that the duration is very short, making the height loss small,
and you do not need to increase airspeed to do it.


Gilbert

Slipping turn on low rope break???? (We are talking "just a bit above
200' rope break" right?)

No, I have never considered this........I see no benefit and some
serious problems.......

Steep turn (about 45 degrees bank)...yes......if you consider the
two major factors in the 180 turn, time and sink ......you come out
with around 45 degree bank as the optimum combination.....It will
yield the least loss of altitude......remember that you need to "roll
up" to 45 degrees and "roll out" to level....so its steep only in the
middle portion of the turn.

Airspeed should be approx the same as a "normal" pattern.....but no
time to be looking at the indicator, (has too much delay anyway) so
simply establish the "normal" nose slightly down attitude....and
coordinated turn...

But a slipping turn???? I don't want to loose excess altitude in the
turn......I want to complete the turn with the least possible loss of
altitude......once I "know I can make it" I reach for spoilers...
(like 3/4 the way thru the 180) then, on (downwind) final, use
spoiler as nesessary, and add slip if necessary....but no slip in the
turn!


Cookie

In article ,
Gilbert Smith wrote:


Have you ever considered a steeply banked side slipping turn ?
You may have a high rate of descent, but the radius of turn is so
small that the duration is very short, making the height loss small,
and you do not need to increase airspeed to do it.


We know that angle of attack is the concern in stall avoidance....any
stall spin accident off of low rope break has to have had too much
angle of attack, one way or another....This means too much stick back
pressure....This is why I like to see an obvious stick forward and
nose pitch down reaction upon rope break.....also smooth control
inputs....

Gilbert

What is the benefit of slipping?


On the topic of a non-coordinated turn at low altitude:

This happened at the Auburn-Opelika Airport (AUO). I was present when an
old-timer CFI was instructing a friend of mine to do this or I wouldn't
have believed it. His advice for making a turn back at low altitude
after an engine failure (aircraft was a Piper Warrior):

"Keep the wings level and turn as tight as you can with just the
rudder".


That has to be the scariest thing I have ever heard an instructor say.
Far worse than the CFI-G in our club who was constantly warning students
about loss of airspeed due to turning downwind...

On Jul 14, 8:43*am, Berry wrote:
Far worse than the CFI-G in our club who was constantly warning students
about loss of airspeed due to turning downwind...


Many people argue that this is not real and base their argument on the
fact that the glider is moving in the air so the glider does not see
the wind speed difference. While that's true it ignors the very
important point that a pilot will, particularly at low altitude, and
particularly if not monitoring the ASI and yaw string, tend to make
control inputs based on the observed movement of the glider over the
ground.

The effect is real. If you haven't experienced it be thankful. The
two fatal accident after rope breaks in strong wing conditions may be
related to this.

Andy

In article
,
Andy wrote:

On Jul 14, 8:43*am, Berry wrote:
Far worse than the CFI-G in our club who was constantly warning students
about loss of airspeed due to turning downwind...


Many people argue that this is not real and base their argument on the
fact that the glider is moving in the air so the glider does not see
the wind speed difference. While that's true it ignors the very
important point that a pilot will, particularly at low altitude, and
particularly if not monitoring the ASI and yaw string, tend to make
control inputs based on the observed movement of the glider over the
ground.

The effect is real. If you haven't experienced it be thankful. The
two fatal accident after rope breaks in strong wing conditions may be
related to this.

Andy

Slaps head: I knew I should not have mentioned the "downwind turn".

On Jul 15, 4:43*am, Andy wrote:
While that's true it ignors the very
important point that a pilot will, particularly at low altitude, and
particularly if not monitoring the ASI and yaw string, *tend to make
control inputs based on the observed movement of the glider over the
ground.

The effect is real. *If you haven't experienced it be thankful. *The
two fatal accident after rope breaks in strong wing conditions may be
related to this.

Don't you people have ridges?

I don't think anyone would be likely to get to solo here without being
very aware that the direction the glider is pointing has little to do
with the direction it is moving, and having experienced this a number
of times in 20+ knots winds, at low level, while doing a lot of 180
degree turns, with the instructor pointing it out if the string didn't
stay in the middle.

It was noted...

While that's true it ignores the very
important point that a pilot will, particularly at low altitude, and
particularly if not monitoring the ASI and yaw string, tend to make
control inputs based on the observed movement of the glider over the
ground.

Not to whip a wounded horse, but this particular form of Darwinism (i.e.
"...not monitoring the ASI and yaw string") - apparently real enough per U.S.
accident lore/history - ought to serve as another reminder to
experienced/complacent/concerned pilots as to the conceptual soundness of
internalizing the fundamental thought, "This sort of accident *could* happen
to me...if I don't [do whatever] properly."

Inertial and vertical-wind-gradient effects noted, the plane does NOT know or
care what the wind-field is doing.

Bob - I believe mindset matters - W.

P.S. No need to quibble over what 'monitoring' means; if you have
useful/usable data available, using it is better than not using it when not
using it increases your chances of dying.


The effect is real. If you haven't experienced it be thankful. The
two fatal accident after rope breaks in strong wing conditions may be
related to this.

Don't you people have ridges?

I don't think anyone would be likely to get to solo here without being
very aware that the direction the glider is pointing has little to do
with the direction it is moving, and having experienced this a number
of times in 20+ knots winds, at low level, while doing a lot of 180
degree turns, with the instructor pointing it out if the string didn't
stay in the middle.

Berry wrote:
In article ,
Gilbert Smith wrote:


Have you ever considered a steeply banked side slipping turn ?
You may have a high rate of descent, but the radius of turn is so
small that the duration is very short, making the height loss small,
and you do not need to increase airspeed to do it.


We know that angle of attack is the concern in stall avoidance....any
stall spin accident off of low rope break has to have had too much
angle of attack, one way or another....This means too much stick back
pressure....This is why I like to see an obvious stick forward and
nose pitch down reaction upon rope break.....also smooth control
inputs....

Gilbert

What is the benefit of slipping?



To keep the inside wing from stalling during the turn? I have read a few
articles which recommend "slightly" slipping in a turn to prevent a tip
stall. A few other articles which pointed out that for the yaw string to
be straight in a turn, too much rudder needed to be input (because addition
of thr the sink rate shows the yaw string offset to the outside)