To Alan Larson.

I tried to reply to your questions directly, but your spam filter doesn't
seem to like my tiscali email address. So the answers a

1) How high you get depends on the length of the run, the power of the
winch (ours are Skylaunches with plenty of power and good control) and the
headwind component. At my club we typically get about 1600ft in no wind and
2000ft launching into a 10 knot headwind. Our standard aerotows are 2000ft,
but you can go as high as you like, depending on your needs and the depth
of your wallet.

2) A wingtip touching the ground during an aerotow ground run is not
normally an issue for aerotowing, provided that it's on a smooth surface
or very short grass. Having said that I once did £5.5k's worth of damage
to my glider trying to aerotow out of a cowfield with rather clumpy grass,
when I caught a wingtip in a particularly lush clump before I could get the
wing up and groundlooped violently. With a winch launch, because you are
putting in a lot of energy very quickly, a cartwheel can develop very
quickly; hence the need to abort the launch if a wing drops.

You also have to fly the glider in such a way that you can always recover
from a launch failure, which basically involves a short initial safety
climb and controlling the rate of rotation. If you pull up like a Saturn
rocket taking off, you are in severe danger or either flick spinning on
the cable, or stalling heavily into the ground if the cable breaks or the
winch fails early on!

3) It's surprising how often you find a thermal straight off the top of a
winch launch. I suppose this is because the heat generated by the winch
engine triggers off a thermal. Otherwise you head off to the nearest
cumulus cloud, or look for birds or other gliders circling. It is
considered polite to move out of the way before the next glider is ready
to launch and not to circle low down in the base leg area, but that often
allows 5 minutes or so in which to climb, by which time you may be high
enough not to conflict.

4) When training new members we normally start them off with aerotows to
get them used to being in the air and to learn how to control the glider
before transferring to the winch. Having said that, many UK clubs do all
their training by winch.

5) For obvious reasons you have to have a system in place that prevents
aerotows and other aircraft from taking off at the same time as a winch
launch is taking place. We have an appointed 'launch point controller'
whose job it is to coordinate all movements by radio. We also place the
winch launch point about 500 yards in from the downwind boundary and on a
grass area away from the main runway, so most gliders, tugs and light
aircraft can land short of there without conflicting with the cables.
Unfortunately this costs us some potential launch launch height. If we use
the full length of the airfield (1900yards) we can get 2500ft winch
launches even in nil wind. We sometimes do this when things are quiet, but
then you have to stop launching whenever there is an aircraft or glider on
approach. Also the higher you take the cables, the more likely they are to
drift over something expensive after a cable break.

Regards,
Derek Copeland






At 13:30 09 July 2009, Del C wrote:
Pros and Cons of winch launching:

PROS:

1) A new professionally built winch will probably cost less than a new
towing aircraft. If you build your own from scrap automobile/truck parts
it will cost considerably less.

2) A winch doesn't require a highly qualified and certificated driver,
Certificates of Airworthiness, 50 hour checks, etc, etc. Some routine
maintenance is required though.

3) Low carbon footprint. A winch launch consumes less than a fifth of
the
fuel required for an aerotow

4) No aircraft noise complaints.

5) Given proper training and pilot awareness, it's pretty safe.

6) Winch launching is cheap; at our club less than a third of the cost
of
a 2000ft aerotow, even with professional winch drivers. So ideal for
training and circuit bashing. A decent soaring pilot can usually get
away
from the sort of heights achieved, in the right conditions.

7) You don't have to learn accurate formation flying behind a tug.

8) You are unlikely to kill the winch operator, as opposed to a tug
pilot
who can be killed if you get too high or too out of position.

9) Above all IT'S FUN.

CONS:

1) Launch height is limited by by the length of the cable run and the
headwind component. On a still day you will at best get about 45% of the
cable run. Launching directly into a headwind will improve this.

2) You can't get towed to a source of lift, such as a cumulus cloud or
a
ridge. You always end up right over the winch.

3) Pilots need to be fairly well trained and switched on to deal with
launch failures and cable breaks.

4) Winch Cables may conflict with power flying at a mixed operation
site.

Derek Copeland