Mike Borgelt wrote in message . ..
On Sat, 25 Oct 2003 12:43:35 -0700, "Gary Boggs"
wrote:

Someone must have already compared the safety of these tow launch methods.
What do the statistics show is the safer method of launch? Aero tow seems
to involve more inherent dangers to me. For one thing, there is just more
time for things to go wrong. What could be more dangerous than to tie tow
airplanes together and try to fly?

Gary Boggs


I've only done about two winch launches but have done several hundred
car tows and driven several hundred also.

Two winch launches. Helps to understand why you say what you say later
on.


Ground launches involve lots of wire, rope etc. It is probably a good
observation that the more rope you have the more trouble you can get
into! With one exception below.

I've had the glider run over the wire and tangle in the wheel well.
Not good as you now cannot release and depend on the tow driver..

Pilot reactions to a low altitude winch launch failure are utterly
critical. I suspect we've killed dozens if not hundreds over the years
this way around the world.

Yes, the reaction is critical. But even more important is the correct
attitude corresponding to airspeed and altitude at all times. This
does make the reaction when something goes wrong a quite a bit less
critical.
I guess we have about 0.5 cable breaks and 2 or 3 weak link breaks per
1000 launches. We do about 3500 winch launches a year. It can happen
and if the pilot is properly instructed he knows this and is prepared.
I do not consider cable break or engine failure to be a _problem_ when
launching even when it happens.


You may need more than one launch to get away(rare with aerotow).

Normally not.

Someone mentioned the stresses in the wire and the glider. Both are
much lower in properly executed arotow.

Stresses are normally higher, but where's the problem in that? The
glider is built to easily take those stresses and we change the wire
once a year anyway.


Aero tow may have a higher exposure to an off airport landing in
unsuitable terrain but the failures seem to be much more rare than
winch wire breaks. If you don't use toy towplanes(less than 180HP)
then any place suitable for winching probably gives you the
opportunity to do a 180 or land straight ahead from an aerotow.

Definite 'No' on the 'probably gives you' bit.
From a winch launch you should _always_ be able to land on the
runwyay. I know lots of airfields where you have a certain time,
sometimes only two or three seconds, sometimes ages, in the aero tow
when you definitely do _not_ want _anything_ to go wrong. The
suitability of the airfield for whinch launching has no relevance
here.


If you want gliding to be popular aerotow involves less running around
on the ground per flight hour.

Don't see why. Only thing to do additionally is retrieveing the winch
cable. And the guy drives, he doesn't run.
And: If you want gliding to be more popular among the people living
near the airfield you should stop making such a racket with those
ancient technology fuel to noise converters. Instead we do 80% of our
launches with 0.4 litres of Diesel.


Flying towplanes is more fun than driving a winch or tow
car.(Allegedly - I last sat in a towplane in 1971 writing down CHT's
for the cooling test for 4 tows in a row and haven't felt motivated to
get into a towplane since despite the aquisition of a PPL 9 years ago)

Aerotowing danger can be reduced by using a longer rope. One of the
local clubs around here tried it and liked it so much the towpilots
won't fly with short ropes. The long rope gives everyone more time to
handle upsets. I suspect the rise of the towplane upset accident
coincided with using shorter ropes.

Agree to all that.

Regards
Marcel