In the UK, Holland and Germany about two-thirds of glider launches are done
by winch, so we have a fair bit of experience in this technique. Prior to
about the early 1980s winches were fairly asthmatic things, but the sort
of ideas that Bill is advocating now where tried out as more powerful, big
engined winches such as the Tost and Van Gelder, became available, and
where quickly found to be somewhat dangerous! As the Americans are at last
starting to get into winching, I am just trying to stop them re-inventing a
rather dangerous wheel. All you have to do in reality is to slightly
restrict the power given to those types of glider that can't safely use
it!

Even a fully automated, computerised winch can fall foul of finger trouble
in inputing the launch data, so even there it is best to err slightly on
the size of caution.

Bill has suggested that slowly accelerated launches are more likely to
cause flick spins. That being the case we should have had plenty of these
when we autotowed, where the acceleration is very slow, but we didn't!

If you have a system or a gadget that you can clamp to a winch to directly
measure cable tension, I for one would like to know about it. RLTs seem to
be limited to about 40mph maximum cable speed, which is not enough. The
other approach is to mount a load cell in the glider's hook mount, or at
the glider end of the cable with a radio transmitter to transmit data back
to the winch. The former would be rather expensive for glider owners and
for clubs with a lot of gliders, while the latter would be prone to
breakages when dropped from 2000ft!

Derek Copeland


At 09:59 25 March 2009, bagmaker wrote:

I would support a fair bit of what Bill says, which may be why my
previos post has been ignored.

Many of our sports members fall into the old dogs and new tricks area,
I have a feeling the more experience one has in anything, the more they
push against change, especially as we grow older.

I must disagree with Dereks' statement on measuring tension as well, it
is a simple thing to do. Perhaps it hasnt been done, sure, but its not
hard. (Caveat- I sell loadcells and measurement equipment for a
living)

As I have stated, If we can identify we have a problem (we do, people
have died) why would we not change? Technology is allowing change,
embrace it.
If, with respect of time, we see we were wrong and can change back,
what harm? At least we tried.

We can set up winches to do any damn thing we like, every time,
regardless of wind gusts, temperature changes, altitute differences,
ballast, number of pilots, student requirements, winchperson ability,
emergency airspace violations etc, etc. So lets!

If you dis-agree, dont fly off the new winch, simple!


Bagger




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bagmaker