A Dummy's Guide to Safe Winch
Launching
Cape Gliding Club
Safety on the Ground
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Safety at the launch point
Safety at the landing area
Safety at the winch
Launch point – prior to launch
Launch point: during launch
Landing Area
Landing Area: touchdown
Safety at the Winch
Safety Through Equipment
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Critical equipment should be manufactured
and maintained to aircraft standards.
Safety critical items (from the glider to the
winch)
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Release
Rings
“Snake”
Weak link set
Guillotine
Release
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Tension load with winching is much higher
than with aerotow – (similar to all up mass
of the glider).
Must hold tension.
Must release reliably, without excessive
operational force – even when under high
tension.
Back release must hold until the correct
angle is achieved – even under high
tension.
Hand tests cannot simulate actual operation
conditions.
Rings
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Must not be cracked.
Must not be distorted.
Dimension and shape of small ring critical in
ensuring correct operation of release.
If overloaded the large ring will distort
before the small one.
“Welded” rings work for aerotow but not for
winching. We must use imported forged
rings (Don't loose them - 28 Euro's per set).
Snake (or “strop”)
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Must be stiff so that it cannot get hooked up
in the main wheel or elsewhere on glider.
Must long so that the glider will not fly into
the chute after a cable break.
Must be light:
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Prevent damage when snake springs into glider
after weak link break.
Should not fall into and upset cable chute after
release.
Different countries use different designs.
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(Thick rope, weak links mid way down strop)
Weak links
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Coded by color and number
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#1 Black (DG 500 22m)
#2 Brown (Twin Astir, flown dual)
#3 Red (ASK13)
#4 Blue (LS3, LS4, ASW20)
#5 White (Standard Cirrus, Single Astir)
Check glider flight manual for correct weak
link and maximum winch launch speed.
Weak links (continued)
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Main link has round holes, always takes
load
Reserve link has slotted holes, is only
loaded after main link has failed. (Optional)
Main and reserve have different center
holes.
NEVER fit two main, or two reserve links at
the same time, this will double the breaking
load.
Weak link protector has a slot and a hole.
Install with slot facing glider – protector
must stay with the cable.
Guillotine
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Must work when needed:
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Proven design.
Quality manufacture.
Properly maintained.
Regularly tested.
Keep cable cutter at hand in winch during
launching as emergency backup.
Safety in the Air
4 Key Aspects to Safe Winch
Launching
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Wing drop during ground run
Rotation
Launch profile
Emergencies
Wing Drop During Ground Run
“The Cartwheel Accident”
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HOLD the release (but don't pull it) during
launch.
If the wing touches the ground RELEASE
IMEDIATELY.
Procedure:
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Complete all checks and radio call before
accepting cable.
Keep your hand on the release after hook up.
No hand signals – wing runner is in control of
launch.
Six Seconds to Near Disaster
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From and article in Sailplane and Gliding.
Lasham Gliding Society, UK.
Instructor was wearing gloves and hand
slipped off release.
Take note where the glider comes to rest.
Take note of the traffic cone (defines “start
line”).
Why hold the release instead of
keeping your hand near it ?
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Photos taken from a report on the
investigation of a fatal “wing drop” cartwheel
accident.
ASW 20: (Release on Left)
Position of stick and release with full left
aileron (to correct right wing down).
Can you locate and operate release with left
hand while holding stick in this position
with right hand?
Another Launch
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Clap your left leg when you think it is time to
release.
Instructors: How much time do you give
your pupil before you release?
Note how far the glider moves off the center
line of the runway.
Correct Rotation
(Avoiding a snap stall)
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Rotation during launch is similar to an
aerobatic pull-up maneuver – like an entry
into a loop. (A loop can pull 4 G's)
Typical Stalling speed:
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Level Flight 65 km/h
While pulling 2G's, 92 km/h
Rotation must be limited to a nominal “7
degrees per second” to ensure excessive
G's not pulled.
5 seconds from beginning to end of rotation.
Typical winch launch profile
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Do not “force” the glider to take off.
Do not rotate too soon.
Do not rotate too rapidly.
Ensure you can recover safely from any
point on the winch launch.
Emergency Procedure in Event of a
Cable Break:
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Lower the nose – to the attitude you would
use for a landing approach from your
current position
Release the (remaining) cable.
Wait for the airspeed to recover – check
your ASI.
Do not use controls (aileron, rudder or
airbrakes) before you have recoverd flying
speed.
If you have enough runway to land ahead
then land ahead.
Otherwise make and execute another plan.
Doing it Right
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From the Water Front in Cape Town
To above Lion's Head
In about 45 seconds.