Nimbus 4DT accident 31 July 2000 in Spain.

Good comments, Don.

If the break occurs between the winch and drogue the 'chute will collapse
and pass harmlessly below the glider, releasing automatically from the
glider in most cases.

If the break is between the glider and drogue, (weak link failure) then the
drogue will be open as long as the winch driver maintains power. In this
case, the winch driver is the key. My driving technique is to cut the
throttle and let the drogue collapse and drop to the ground. Comments?

The worst case that is very rarely seen is that somehow the glider gets in
front of the drogue and it overtakes the glider from behind. This is the
equivalent of getting an air tow rope entangled with the glider. Both are
equally rare. This is why once the drogue is on the ground, the winch
driver must not move the cable until he hears that it is safe to do so.

It is very important to point out that almost all the cable breaks were
using the old steel wire. The new Dyneema winch cables rarely break. The
last I heard, Aero Club Landau in Germany had more than 4000 launches on
their 'plastic' cable without a single break. ACL is also getting more than
1200 meters AGL with their winch launches.

Bill Daniels

The pilot is trained not to land on the wire if at all possible.
"Don Johnstone" wrote in
message ...
Just to add to what Bill has said, the really low launch
failure 100 is one of the minor problem areas. If
the launch is flown correctly it can be quite safely
handled. The good point is, as Bill has pointed out
that there is a large amount of airfield still in front
of you. The bad news is that by the time the nose has
been lowered the airspeed may be below the minimum
allowed for the deployment of airbrakes. It may not
be possible to lower the nose any further to increase
the speed because of the proximity to the ground and
therefore a touchdown has to be achieved without using
airbrake. Patience is required as most modern gliders
float a long way even at 50 kts in ground effect. (Grob
103 will travel the length of the 10000ft runway at
Marham from 20ft/60kts) Simulating a launch failure
at this height is not recomended as there is a real
danger that the drogue will inflate as the winch driver
cuts the power and drape itself over the cockpit. The
good news is that such breaks are rare as the strain
on the cable is reducing before increasing again. The
procedure can be simulated by carrying out a faster
than normal approach, pulling up and closing the airbrakes
and then recovering from that situation which puts
the glider in the same situation as a low break but
without the cable in the way.


At 04:30 28 June 2005, Bill Daniels wrote:

'Kilo Charlie' wrote in message
news:9D3we.3579$Qo.3471@fed1read01...
Your input re winch launches is appreciated Bill....esp
for those of us
that
have never done one!

Please don't take this as a criticism of winch launches
but through this
thread there has not been any mention of what happens
at the critical low
level altitude when the cable breaks. There is clearly
also a zone of
real
problems with aerotows too.....esp here in the desert
with few, if any
landing options straight ahead. What do you guys
teach re breaks at 100
feet? It seems like landing ahead would be good but
how much altitude
does
it take to regain the necessary speed to be able to
control the glider for
landing when at a high angle of attack? Sorry if
this is too obvious for
those of you that do it all the time!

Casey


Thanks, Casey.

The climb profile must be such that a safe recovery
with generous margins be
possible from any height that a cable break occurs.
Safety is the product
of airspeed, altitude and attitude - and good training.

If the break happens at 100 feet, then 90%+ of the
runway lies ahead to
receive the glider. At 100 feet, the glider will have
full climb airspeed,
approx. 60 knots, but then pitch attitude will only
be 20 - 30 degrees. A
prompt, gentle pushover to a glide at approach airspeed
is all that is
needed to land straight ahead.

If the break occurs higher, say 300 - 400 feet, then
the straight ahead
landing is still possible with spoilers but a tight
360 pattern is also
possible. The two options overlap by a good amount
of height depending on
the airfield. At this height, the climb attitude will
be about 45 degrees
nose up (although from the cockpit it will feel like
60 degrees) so a more
aggressive pushover is needed.

All these situations will be practiced over and over
until the instructor
feels the student reacts instinctively and correctly
to each. The student
must firmly push the nose down until the airspeed is
observed to be at a
safe value and increasing before establishing a glide
for a straight ahead
landing or a turn for an abbreviated pattern.

I must admit that winch launch LOOKS scary and FEELS
scary to the
uninitiated but the procedures worked out over literally
tens of millions of
launches in Europe and elsewhere make it actually safer
than air tow.

As for releasing over the winch instead of wherever
the tow plane takes you,
I see by looking at a lot of On-Line Contest IGC files,
that most air tow
releases happen within a mile of the takeoff point
and the glider is rarely
in a thermal at release but must glide around looking
for one just like with
a winch launch. If you don't find a thermal, a winch
re-light will cost you
less than $10.

The latest European winches are getting even heavy
gliders to over 1000
meters AGL so finding lift shouldn't be a problem.

Bill Daniels