On Friday, May 10, 2013 7:11:07 AM UTC-5, Don Johnstone wrote:
At 02:45 10 May 2013, Bob Kuykendall wrote:

Don, I can respect that you have reservations about the method in

question. But it would be a lot more constructive if you'd provide

specific examples of why the method in question is inadvisable, and

are prepared to tell us how it can go wrong. Otherwise, when you call

people "foolhardy" and tell them flat out to "stop it," you mostly

just come across as a disagreeable curmudgeon.



Furthermore, I think that anybody who has used a winch but decries the

"complexity" of other ground launch methods does not really understand

how complex a good winch is, and how many points of failure there

really are.



Thanks, Bob K.



Fair point Bob



If we consider the simplest winch where the engine is connected to a

transmission via a gearbox of some kind. In this type of winch the driver

is seated and controls the throttle to control the speed of cable

retrieval.



What can go wrong? Three basic things as regards the operation of the

winch.



1. A break in the cable

2. A mechanical failure of the winch

3. Winch driver error or incapitation.



All of these eventualities are dealt with by practising launch failures or

launch abandonment. As far as mechanical failure of the winch is concerned

there are only two main components to fail, the engine (Uncommon but not

unknown) and the transmission. In all cases the winch driver is seated with

a good view of what is going on and can react to problems as they arise, in

particular using the guillotine if required in a timely manner.

The first winch I drove was of this time, a 3 litre petrol engine driving a

winch drum through a conventional 4 speed gearbox.

The most complex winch I have driven was a Munster Van Gelder winch with a

ginormous turbo diesel engine providing power for 6 seperate drums through

a torque converter. The engine control, transmission and drum select

functions were complex but once the transmission was connected to the power

module the principle was the same as for the simple Eagle winch described

above. Failure of either winch by mechanical failure of the

engine/transmission during launching was very rare. The MVG winch was

however less reliable in that faults within the more complex system meant

that it was U/s far more often than the simple winch, and took longer to

fix. Having said that the components making up the MVG winch were of top

quality and specifcally designed or adapted to provide the proper function,

it was just that there were more components to go wrong. In both cases the

winch was fixed, the driver had control and could see the glider at all

times and take the appropriate action.



The payout winch provides an additional level of complexity and reduces the

ability of the operator to control the launch. Some aspects of the launch

rely totally on unsupervised mechanical/electrical operations, the payout

part of the operation. The system is really a combination of two launch

methods, an auto tow and a winch launch and is just one level of complexity

too much when the proven technology already exists to provide a good

launch without introducing more complex procedures, especially ones which

rely totally on a mechanical/electrical function with no human input or

control.

During an auto tow the driver is facing the wrong way or is peering over

his shoulder so his ability to offer proper control or reaction to an

emergency is compromised, add to that the fact that cable payout is taking

place while the vehicle is moving in the opposite direction and while the

glider is on the cable and the things that can go wrong increases

exponentially.

Winch launching has hazards, no denying that, some of them completely

outside the control of the winch operator. A fixed winch with the operator

in a good position to observe the launch provides the best and safest

solution.

I have of course assumed that the launch is contolled by one person, the

implications of having two people controlling a launch (or not) are too

horrible to consider. I cannot see that anyone would be daft enough to do

that.

I can see that the payout winch launch is dangerous, I have said so. I may

or may not be believed. Like all human activity it will continue until

something goes wrong. If god forbid someone is killed then many people will

pipe up saying they knew it was dangerous, I am just saying it in the vain

hope that people will look at what they are doing and see that however

attractive it might seem it is not woth the risks, before it ends in

tears.

Bottom line, a vehicle driving down a runway with a glider on tow and a

winch paying out cable while the launch is taking place is not something

that I would ever be involved in. Been gliding and winching for 50 years

and would like to continue for a few more years.

Interesting dichotomy between the European and American viewpoint. Being trained on the winch learning to soar and having 3,000 winch launches done from the winch driver seat I tend to agree with Don. To add to his points: A winch launch (1 km cable length) gets you to 1,300 - 1,600' altitude safely and cheaply. You learn to climb away from that altitude even in poor weather, or you land and do it again. I just don't see the need for winching to 2-3k feet in a glider and if you disagree you probably have some thermaling to learn. I witnessed a hang glider accident with a payout winch on a pick-up truck and it was not pretty. We asked the hang glider group to not fly from our site any more...
Herb