Central Otago Flying Club

Letter from Central Otago Flying Club Winch Rope

Hi Jonas
Thought I'd drop a line to let you know that we have used our new winch rope (4mm Dynex) for the about 30 launches.
I can report great success.

Release Height
We now get consistently good launches of 1,800ft in our two-seater. This is 300ft higher than with the Polyester braid and wire combination we used previously.
This was 800mtrs steel wire on the drum end, and 1,000mtrs 8mm polyester at the glider end.
When we used only steel wire (6mm), winch heights were 800-900ft.

Winch Power
An unexpected benefit is that the winch requires approx 20% less power to launch a glider. Previously in nil wind 100% power was often not enough for the two-seater.
Engine revs are also reduced. We had expected that we may have had to replace the engine with a more powerful model. It now seems unnecessary.

Connections & Joins
Almost any type of a knot seems ok to connect to rings etc, and a simple type of fisherman's knot to the nylon shock cord.
We'll use an inline splice in the event we need to join two pieces.

Only 4mtrs is ok for shock cord. I did a launch without the nylon, and found there was some vibration coming from the rope winding on the drum.

Safety
Safety is greatly improved. In the past using steel wire was a risky operation. Large tangled masses of wire could occasionally be moving toward and around the drum at high speeds, after a cable break. The wire was sometimes shattered against the winch framework, sending pieces of wire in all direction. A strand of wire was once punched straight through the back hatch door of my car. It can be difficult for the driver to be certain that there are no bystanders closer than they should be. Long lengths of wire could fall from the sky in an aborted launch, or if the parachute did not operate.

Cost savings
The club has a prepay package to solo which includes all launches. The increased launch height is great for training students on nil wind days.
Reducing the number of aerotows for prepay students will save the club considerable funds.
More launches can be done in a day. A lot of time was taken repairing wire breaks, with gliders waiting and not earning.
Last year we used about 100 wire joining crimps at $2.50.

Reliability
With no wire, we are expecting to have very few problems. The 30 launches so far without a cable break is probably a record for our winch.
If you or any of your staff are in the area, we would be very pleased for you to experience a winch launch for your self's and fly with us.

Cheers
Pete McKenzie