"Graeme Cant" wrote in message
...
Exactly. You equated no cable breaks to no launch failures.

The discussion was about a field where cable breaks couldn't be
practiced. Simulated cable break is how winch operations train their
pilots to handle ALL premature terminations of the launch - weak link
failure, engine failure, failure of the laying gear, jams in the feed
rollers, even the drum falling off because of fatigue cracking of the
hub, even sometimes, the Dyneema failing.

OK, I see your point. Launch failures can occur for other reasons than
cable break. However, those that you mention can be largely eliminated by
good design and mantenance. The most common reason for launch failures I
have seen other than cable break is the winch running out of gas. That's
pretty easy to deal with.

Replacing steel wire with Dyneema/Spectra itself eliminates a lot of failure
modes since the stuff really doesn't want to tangle or jam. Reducing the
rotating mass of the drum helps too. 5000 feet of 3/16 inch wire rope
weighs about 300 pounds. The same amount of Spectra weighs about 50 pounds.


The reliability of the cable is the straw man in this argument. I don't
care if the Dyneema never breaks, if there's no way of practising
premature termination of the launch skills and procedures, the field is
unsuitable as a base for winching.

Absolutely agree. If you can't practice launch failures, the field is
unsuitable.

There was some scepticism expressed that it would be suitable for
aerotow if it wasn't suitable for a winch. I think that's a good
question but neither of us have seen the field so there's nothing useful
we can say on that.

If a launch failure of air tow or winch would put the pilot at risk, there
needs to be some serious thinking about proceedures.

Bill Daniels