A Dummy's Guide to Safe Winch Launching

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A Dummy's Guide to Safe Winch Launching

• Cape Gliding Club

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Safety on the Ground

• Safety at the launch point
• Safety at the landing area
• Safety at the winch

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Launch point prior to launch
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Launch point during launch
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Landing Area
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Landing Area touchdown
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Safety at the Winch
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Safety Through Equipment

• Critical equipment should be manufactured and
  maintained to aircraft standards.
• Safety critical items (from the glider to the
  winch)?
• Release
• Rings
• Snake
• Weak link set
• Guillotine

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Release

• 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.

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Rings

• 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).

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Snake (or strop)?

• 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
• 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.
• (Thick rope, weak links mid way down strop)?

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Weak links

• Coded by color and number
• 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.

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Weak links (continued)?

• 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.

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Guillotine

• Must work when needed
• Proven design.
• Quality manufacture.
• Properly maintained.
• Regularly tested.
• Keep cable cutter at hand in winch during
  launching as emergency backup.

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Safety in the Air4 Key Aspects to Safe Winch
Launching

• Wing drop during ground run
• Rotation
• Launch profile
• Emergencies

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Wing Drop During Ground RunThe Cartwheel
Accident

• HOLD the release (but don't pull it) during
  launch.
• If the wing touches the ground RELEASE
  IMEDIATELY.
• Procedure
• 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.

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Six Seconds to Near Disaster

• 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).

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Why hold the release instead of keeping your hand
near it ?

• Photos taken from a report on the investigation
  of a fatal wing drop cartwheel accident.

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ASW 20 (Release on Left)?
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Position of stick and release with full left
aileron (to correct right wing down).
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Can you locate and operate release with left hand
while holding stick in this position with right
hand?
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Another Launch

• 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.

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Correct Rotation(Avoiding a snap stall)?

• 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
• 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.

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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.

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Emergency Procedure in Event of a Cable Break

• 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.

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Doing it Right

• From the Water Front in Cape Town
• To above Lion's Head
• In about 45 seconds.

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