On Jul 12, 12:45*pm, Andreas Maurer wrote:
On Sun, 12 Jul 2009 12:45:08 +0200, Marian Aldenhövel

wrote:
... yet thousands of clubs in Europe with much, much more winch
experience than any club in the US don't see the need for such a
system.

Some do.

Indceed some do - but very, very few.
If there really was an urgent need we'd have more than a couple of
such winches in Europe by now, don't you agree?

When I was trained as a winch driver I was taught to judge cable tension
and use that as the input parameter to the control loop. The only way of
doing that without special sensors is to look at the cable sag. Works
during the main portion of the launch, but is not very accurate of course.

But sufficiently accurate, isn't it?
Contrary to the believe of some people here it doesn't matter if the
speed during the winch launch is 5 kts faster or slower (although the
perfect speed certainly increases launch height).

I think if the winch, or winch driver, has the means to control tension
and the pilot controls airspeed winch launches become more efficient and
even safer. Reports suggest that, I have no experience of my own.

Efficiency? Definitely.
Safety? I doubt it.
I havent't been able to find even one accident report that was caused
by inappropriate power setting by the winch driver, yet there are
comparably many accidents caused by rope breaks or complete power
losses of the winch - things that cannot be prevented by tension
controlled speed.

Also you would propably get much more consistent launch performance
across different conditions and much more important, different drivers.

Indeed. Nice to have.

Today we get launches like being shot from a carrier deck and the
lumbering wingrunner-testing type all in the same day depending on who
is manning the winch. The first launches of the day, or after a driver
swap, or when conditions change would no longer need to be different
than those by a well-adapted driver.

Typical problem of winch driver training. Once we started to re-train
our winch drivers who had problem scontroling the speed, we got rid of
this problem.

Viele Grüße
Andreas

By those standards, starting cars with hand cranks was 'adequate' and
electric starters would be 'nice to have'.

In fact, tension control is relatively new technology based on vastly
increased knowledge of winch launch dynamics. It certainly has the
potential to increase safety in those cases where unexpected weather
or a human winch operator creates unexpected conditions.