A Dummy's Guide to Safe Winch Launching

Cape Gliding Club

Safety on the Ground

➲ 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

➲ 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

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.

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).

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)

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.

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.

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.

Safety in the Air4 Key Aspects to Safe Winch

Launching

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

Wing Drop During Ground Run“The 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.

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”).

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.

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

➲ 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)

➲ 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.

Typical winch launch profile

➲ 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:

➲ 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

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