Nimbus 4DT accident 31 July 2000 in Spain.

Chris Reed wrote:

One of my favourite exercises for my annual checkouts as a UK Basic
Instructor is the spin off a simulated winch launch (only try this at
height with an appropriate instructor with you!). Simulate a winch
launch by diving to 90 kt and then pulling up at 45 degrees. As the
speed drops to about 60 kt cry "BANG - cable break", and push over into
the normal flying attitude. The moment normal attitude is reached, begin
a co-ordinated turn.


I've recently been doing this as a student and personally I found it a very
valuable lesson as (a) it required no "forcing" from the instructor to initiate
the spin and (b) it makes you realise how quickly you can transition from an
apparently normal flying attitude into a serious situation.

Chris Gadsby

Bill,

In fact, at least according to US regs, a winch launch IS an aerobatic
manuever. But that wasn't my point. If normal recovery from a normal
operation places the pilot on the ragged edge of a deep stall, then I
think it best to characterize the operation as "ab"normal., requiring
reactions unique to that environment. And thus my toying with the term
aerobatic.

There remains a problem with this argument, however. Maybe the subject
of a different thread.

BTW, have you demonstrated this maneuver without revocery? IE, have you
left the controls in place to let the spin fully develop?

wrote in message
ps.com...
Bill,

In fact, at least according to US regs, a winch launch IS an aerobatic
manuever.

I believe you are referring to the +-30 degrees pitch and +-45 degrees bank
definition of aerobatics. I believe there is an exclusion for aircraft for
which these are normal maneuvers. Gliders routinely exceed these values
thus they are not considered aerobatic for gliders.

But that wasn't my point. If normal recovery from a normal
operation places the pilot on the ragged edge of a deep stall, then I
think it best to characterize the operation as "ab"normal., requiring
reactions unique to that environment. And thus my toying with the term
aerobatic.

Normal winch operation does not place the glider on the ragged edge of a
stall. A normal launch places the max AOA very near that for best L/D. A
wire break handled properly with a prompt pushover is flown at a still lower
AOA with the airspeed not dropping below 1.3 x Vs or so. The margin is even
greater when you consider that the pushover is at less than one G so the
stall airspeed is lower.

The wire break training maneuver described by Chris is to show an instructor
candidate what can happen if the student is allowed to mis-handle the wire
break and is WAY outside normal operation.

The whole point is to drum into the instructors who will then insist that
his students learn that the nose must be promptly lowered well below normal
glide and the airspeed seen to be at a safe value and increasing before any
thought is given to a turn. This is to establish and maintain a large
safety margin. In many cases no turn is necessary and the glider lands on
the remaining runway.


BTW, have you demonstrated this maneuver without recovery? IE, have you
left the controls in place to let the spin fully develop?

Yes, It is a normal spin with a normal recovery at least with the trainers
in common use.

The wire break recovery being discussed here is safer and less dramatic than
the equivalent airtow maneuver consisting of a 200 foot AGL release on
departure and a turn back to the runway.

Bill Daniels

Silly me, playing too loosely with terms.

What interests me is that recovery from a cable break, if misapplied,
appears to place the pilot in a very unusual situation. This flight
condition was presented to put into question the abolutism of some
simple control movements that should keep pilots out of danger of loss
of control. So my question becomes one of instructional emphasis. Since
some problems evolve so quickly that thoughtful consideration isn't
always a best first course, some absolutes are needed. But if you are
flying outside normal flight conditions (IE, aerobatics or cable break
recoveries), those absolutes might not apply. Yanking the stick back to
neutral to fix the horizon on the canopy at the top of a cable break
recovery qualifies as departing from normal flight conditions. But I
certainly see the problem you face. We train pilots to take note of a
stick well aft as one sign of an imminent stall. They might not so
quickly recognize that the glider can be stalled with the stick at
neutral under these conditions. Nor might they realize that
coordination of ailerons and rudder has changed at extremely low
airpseed. Thus the opportunity to enter a wing low stall with your
hands and feet in a position that should normally signal safe flight.

All that said, I spent about 15 minutes on Sunday afternoon
experimenting with this maneuver. The results weren't as previously
published, so I'll need to take some time to write up the results. I'll
start this as a new thread.

Bill Daniels wrote:
wrote in message
ps.com...
Bill,

In fact, at least according to US regs, a winch launch IS an aerobatic
manuever.

I believe you are referring to the +-30 degrees pitch and +-45 degrees bank
definition of aerobatics. I believe there is an exclusion for aircraft for
which these are normal maneuvers. Gliders routinely exceed these values
thus they are not considered aerobatic for gliders.

But that wasn't my point. If normal recovery from a normal
operation places the pilot on the ragged edge of a deep stall, then I
think it best to characterize the operation as "ab"normal., requiring
reactions unique to that environment. And thus my toying with the term
aerobatic.

Normal winch operation does not place the glider on the ragged edge of a
stall. A normal launch places the max AOA very near that for best L/D. A
wire break handled properly with a prompt pushover is flown at a still lower
AOA with the airspeed not dropping below 1.3 x Vs or so. The margin is even
greater when you consider that the pushover is at less than one G so the
stall airspeed is lower.

The wire break training maneuver described by Chris is to show an instructor
candidate what can happen if the student is allowed to mis-handle the wire
break and is WAY outside normal operation.

The whole point is to drum into the instructors who will then insist that
his students learn that the nose must be promptly lowered well below normal
glide and the airspeed seen to be at a safe value and increasing before any
thought is given to a turn. This is to establish and maintain a large
safety margin. In many cases no turn is necessary and the glider lands on
the remaining runway.


BTW, have you demonstrated this maneuver without recovery? IE, have you
left the controls in place to let the spin fully develop?

Yes, It is a normal spin with a normal recovery at least with the trainers
in common use.

The wire break recovery being discussed here is safer and less dramatic than
the equivalent airtow maneuver consisting of a 200 foot AGL release on
departure and a turn back to the runway.

Bill Daniels

wrote:

But if you are
flying outside normal flight conditions (IE, aerobatics or cable break
recoveries),

A cable brake during a winch launch is a perfectly normal flight
condition, and as such, is regulariliy trained. Maybe I'm wrong, but it
seems you didn't do many winch launches, did you?

Stefan

Sorry I do not see that finding yourself in a condition
where the nose is well up above the horizon, airspeed
rapidly decaying with the possibility of increase wing
load from hanging cable can be described as 'normal'.
It is a situation we train pilots to recover from but
it also goes against the normal training in that the
reference to the horizon means less than normal.
During the launch the attitude to of the glider to
the relative airflow is within the normal parameters.
As soon as the launch fails, for whatever reason, the
situation becomes abnormal. Lowering the nose to an
attitude relative to the horizon will not result in
instant recovery.
My way of teaching was for the student to carry out
the corrective action and then ask a simple questions.
Do I have the approach attitude? Answer no, correct,
answer yes then 'Do I have the approach airspeed? answer
no, check response to answer yes, if that is still
yes then wait until the answer to the airspeed question
is yes. When the answer to both questions is yes, then
and only then decide on the most appropriate course
of action and implement.

Works for me and I have survived 10000 winch launches

At 12:18 27 June 2005, Stefan wrote:
wrote:

But if you are
flying outside normal flight conditions (IE, aerobatics
or cable break
recoveries),

A cable brake during a winch launch is a perfectly
normal flight
condition, and as such, is regulariliy trained. Maybe
I'm wrong, but it
seems you didn't do many winch launches, did you?

Stefan

wrote in message
oups.com...
Yanking the stick back to
neutral to fix the horizon on the canopy at the top of a cable break
recovery qualifies as departing from normal flight conditions.

We agree. This is the reason for the training scenario which teaches
avoidance of this situation.

But I certainly see the problem you face. We train pilots to take note of
a
stick well aft as one sign of an imminent stall. They might not so
quickly recognize that the glider can be stalled with the stick at
neutral under these conditions.

To stop the nose at the normal gliding attitude after a wire break requires
a powerful elevator and full back stick. This is definitely a pilot induced
stall resulting from a mis-use of the elevator. However, accident records
show that this has occasionally been the cause of a spin accident so the
training scenario was added. To repeat what I wrote earlier, this is merely
a slight variant of an accelerated stall. If the stick were held neutral,
the nose would fall through to a steep nose down attitude. This is not the
best technique but it wouldn't result in a deep stall.

Bill Daniels

On 26 Jun 2005 04:57:20 -0700, wrote:


In fact, at least according to US regs, a winch launch IS an aerobatic
manuever. But that wasn't my point. If normal recovery from a normal
operation places the pilot on the ragged edge of a deep stall, then I
think it best to characterize the operation as "ab"normal., requiring
reactions unique to that environment. And thus my toying with the term
aerobatic.

LMAO.


Bye
Andreas

Don Johnstone wrote:

Sorry I do not see that finding yourself in a condition
where the nose is well up above the horizon, airspeed
rapidly decaying with the possibility of increase wing
load from hanging cable can be described as 'normal'.

We can argue the meaning of the word normal. For me, everything which
happens from time to time and is no surprize is normal. In winch
launches, cable breakes do occur and are to be expected. So they are
normal me, just a variant. But there's no need to argue about this word.

It is a situation we train pilots to recover from but
it also goes against the normal training in that the
reference to the horizon means less than normal.

Again, what is normal? In flat land, during normal flight, the horizon
is the reference, so that's normal. In mountains, having no natural
horizon but only an imaginary one is normal. And in a winch launch, not
referring to the horizon is normal, at least to me.

Lowering the nose to an
attitude relative to the horizon will not result in
instant recovery.

Exactly, that's why, after a cable break (or after "normal" release, for
that matter), ist "normal" not to refer to the horizon in the same way
as during free flight. Different conditions, different techniques.
Nothing abnormal.

My way of teaching was for the student to carry out

I'm sure you instruct your students correctly. The only thing I jumped
on was the statement that there was something "abnormal" in a winch
launch. Again, different conditions require different techniques, which
means different normalities.

This is the approach I take: Normality depends on cirumstance, so
broaden your view and your repertoire of techniques.

Stefan

No. Several dozen.

BTW,

For the purposes of this section, aerobatic flight means an intentional
maneuver involving an abrupt change in an aircraft's attitude, an
abnormal attitude, or abnormal acceleration, not necessary for normal
flight. This is from the US FARs. While we can discuss ad nauseum
whether a winch launch is an aerobatic maneuver... (and really it
isn't), it clearly requries control motions that constitute aerobatic
flight, and as such represent a "special" set of circumstances.

Note that Chris introduced me to a manuever which can be accurately
described as outside the parameters of normal flight (IE, abrupt change
in aircraft attitude). In preparing to defend the efficacy of winch
launching, you're missing my point. There is a disconnect between the
control actions required for safe recovery from a cable break and the
correction of a stall and/or dropping wing during normal flight. My
point is that the cable break recovery is a special case and needs to
be discussed in depth, and differentiated from the "normal" control
movements to establish and maintain controlled flight. But I digress.
This is the subject of new thread.

BTW, I learned to winch launch under the tutelage of a BGA instructor
in Britain. This concern of the snap spin was never discussed. Recovery
of airspeed, certainly, but no warning against starting a turn.

Per the particulars of earlier notes in this thread, I'll offer some
opinions at length based on what I experienced in my glider yesterday,
but it'll be a few days before I can take the time to document them.

Stefan wrote:
wrote:

But if you are
flying outside normal flight conditions (IE, aerobatics or cable break
recoveries),

A cable brake during a winch launch is a perfectly normal flight
condition, and as such, is regulariliy trained. Maybe I'm wrong, but it
seems you didn't do many winch launches, did you?

Stefan