This should make most power pilots have kittens...

Don Tuite wrote:
Ok I'm trying to visualize a winch sucking up cable at 88 feet/second
(60 mph) and 2000 feet of cable accelerating toward the ground at 32
ft/sec^2. And I'm thinking of my experience fishing with cheap
bait-casting reels. Does it ever get interesting?

you bet. Cable breaks are something quite interesting to start
with (especially if you were tempted to pull to a steep climb
too early -- 45 degrees nose up, no engine, and low, is
what I'd called interesting); that's why it is a part of the
training which is emphasized; I have known of accidents that
involved bad ground handling as well: in a place with a multiple
drums winch: only one cable winched at a time, but multiple
cables can be made ready to increase the rate of launches; the
guy I knew got into trouble when the cable he used got
entangled with another cable laying on the ground...

--Sylvain

I was watching a guy launch his R/C sailplane using a winch.


He got a little aggressive and pulled the wings off. G

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html

On Mon, 14 Nov 2005 16:15:01 -0000, Dylan Smith
wrote in
::

At our glider club, we can either use the tow plane or the winch to get
the gliders in the air. Not many power pilots have come across the idea
of flinging an aircraft airborne on the best part of a mile of steel
piano wire, but we do this crazy thing. [Power pilots - whenever you see
the glider port symbol on your chart, remember that there may be a winch
there. They are less common in the US than over here, but they are used
in the US, and the 1/8th inch steel cable will not be kind to you if you
run into it. Never directly overfly gliderports below 3000' without
talking to their radio operator].

We (the Southern California Soaring Society) used to auto-tow gliders
off the dry lake north of El Mirage field in the Mojave Desert with a
1,500' wire attached to an old Buick. There was a lot of other sport
activity taking place on the dry lake at the same time, sand-sailors,
motorcycles, gyrocopters, ... One day a fellow and his girlfriend in
an Aircoup ran into the steel tow wire. The wire imbedded itself in
the wing leading edge up to the spar, and broke, fortunately. The
pilot landed on the field, and inspected the damage, then took off.

Larry Dighera wrote:

an Aircoup ran into the steel tow wire. The wire imbedded itself in
the wing leading edge up to the spar, and broke, fortunately. The
pilot landed on the field, and inspected the damage, then took off.

Ah, they still exist, the real men!

Stefan

On 2005-11-14, Don Tuite wrote:
Ok I'm trying to visualize a winch sucking up cable at 88 feet/second
(60 mph) and 2000 feet of cable accelerating toward the ground at 32
ft/sec^2. And I'm thinking of my experience fishing with cheap
bait-casting reels. Does it ever get interesting? Anybody on the
ground ever lose significant body parts?

Well, there is a small parachute that retards its descent. The cable
doesn't really accelerate much at all when the glider releases - the
speedo on the winch shows about 30mph when we reel it in (but I don't
know what that translates to on cable speed, 30mph would be what the
engine/transmission would be propelling the donor Jaguar XJ6 at!)

It *does* get interesting especially when the cable breaks. Being
pitched up at 45 degrees nose up and perhaps 55 knots indicated and
maybe only 200ft AGL is not a naturally tenable location for a glider
when the power abruptly ceases. It involves a zero-g pushover, then a
dive towards the very terror firma to regain flying speed,
psychologically difficult when all of a sudden you can see every blade
of grass rushing up to smite you.

But generally, so long as you don't 'pole' it too early, you recover
with plenty of time to get your breath back and land. But there have
been incidents where pilots haven't waited for a safe height to pitch
the glider fully up, with a similar outcome to a power plane climbing
out at Vx and losing the motor at 50 feet.

Other interesting things are just with the operation of the winch and
cable. Since we are on a hard surfaced runway (in fairly poor condition)
we use piano wire. A release under tension can create a 'birds nest' -
the wire snarls up on itself, and it's a real bugger to get it
untangled. It's very stiff. Usually we have to resort to cutting the
cable in a couple of strategic places, then tying it (we have tools to
make knots in the cable).

The cable also has a weak link so you don't overstress the glider and
pull the wings off. The Slingsby Swallow, for example, has a different
weak link to the Blanik, being a much lighter ship. Occasionally, a weak
link will get broken when someone gets a bit aggressive on the launch.
There's also a guillotine that chops the cable in case the glider can't
release. Just like pilots are taught a 200-ft turn back to the runway
when being towed by a plane, we also teach launch failures. At sites
with stranded cable or synthetic, the instructor pulls the release
handle on a launch. With piano wire, we simulate it by doing a dive and
a pull up and then the instructor shouts 'BANG!' because when it breaks,
it goes with a bang. (releasing for real on piano wire tends to cause a
birds nest so we avoid it unless we have to!)

How is the behavior of
synthetic rope going to differ from metal cable?

It's a fraction of the weight. The synthetic winch cable for our run (we
have about a mile of cable) weighs something like 25kg, wheras the steel
piano wire probably weighs around 80-100kg. The weight saving translates
into a good couple of hundred extra feet on the launch. Trials at other
clubs shows it's longer lasting than steel (although we have to see how
it goes with our hard surfaced runway) and unlike the piano wire we use
now, it won't snarl up.

Of course, when we get the new winch cable, we're moving from the
carburetted, mechanical points and condenser ignition 6 cylinder engine
to an electronic ignition/electronic fuel injection V12 engine too...

--
Dylan Smith, Port St Mary, Isle of Man
Flying: http://www.dylansmith.net
Oolite-Linux: an Elite tribute: http://oolite-linux.berlios.de
Frontier Elite Universe: http://www.alioth.net

On 2005-11-14, T o d d P a t t i s t wrote:
Dale wrote:

I was watching a guy launch his R/C sailplane using a winch.
He got a little aggressive and pulled the wings off. G

You might find it interesting to know that the gliders have
a winching limit to prevent pulling the wings off when a
human is aboard.

And there's also a weak link on the glider end of the cable in case the
pilot forgets about this limit!

--
Dylan Smith, Port St Mary, Isle of Man
Flying: http://www.dylansmith.net
Oolite-Linux: an Elite tribute: http://oolite-linux.berlios.de
Frontier Elite Universe: http://www.alioth.net

In article ,
Dylan Smith wrote:

Never directly overfly gliderports below 3000' without
talking to their radio operator].

I trust that gliders always announce take-offs...

--
Bob Noel
no one likes an educated mule

Our next winch....... will also be powered by an electronic fuel injected Jaguar
V12 engine which came courtesy of last year's hurricane force storm
which collapsed a garage on top of the donor car, completely flattening
the roof and cabin area of the car, but leaving all the running gear
completely intact :-)

A HA! An Ill wind that blew good!

vince norris

On 2005-11-15, Bob Noel wrote:
Never directly overfly gliderports below 3000' without
talking to their radio operator].

I trust that gliders always announce take-offs...

More importantly, the ground crew give a good look around the sky before
giving the take up slack signal. The rate of climb is phenomenal - we
don't want to launch if it looks like anyone's about to fly over, it'd
be like the Space Shuttle making a take off call just before blindly
launching into whatever might be overflying the field.

But sometimes mistakes are made, or a plane blends into the sky or... so
really, it's best not to directly overfly the field.

--
Dylan Smith, Port St Mary, Isle of Man
Flying: http://www.dylansmith.net
Oolite-Linux: an Elite tribute: http://oolite-linux.berlios.de
Frontier Elite Universe: http://www.alioth.net

Bob Noel wrote:

I trust that gliders always announce take-offs...

Credo #1 in safty seminars: "Never assume!"

Stefan