Am I not right in remembering that one of the pre flight checks is the cable release by pulling backwards on the cable to check it comes off cleanly?

Usually done at first flight of day. Cable on-release with cockpit release under no tension. Cable on- back release. Cable on-release with cockpit release under tension.

Interesting reading this thread, unlike a power question everyone seems to be more or less in agreement!

unlike a power question everyone seems to be more or less in agreement...

Darwin?

Well of course glider pilots are higher up the evolutionary scale...:)

The pilot needs a bit of (re)training to lay off for the x-wind, then. That amount of drift shouldn't be tolerated.

FBW

On my first day of gliding with the ATC I actually witnessed a Tutor glider come straight down from the top of a winch launch. The outer section of one wing broke away as it fell. As far as recall, it was thought that the cable did not release. Sadly the pilot was killed.

Spectra is Lovely
 

Just make sure you get it thick enough.

We had lots of practice with cable breaks with the thin stuff. Our winch went back to the manufacturer for upgrade -- which took two years -- and is just back with thicker Spectra.

There is an automatic cable tension control with airspeed transmitted from the hookup.

Now we get to see how it works.

50+ years ago, when Aberdeen Gliding Club operated at Aberdeen Airport, I saw a solo pilot allow enough crosswind drift to drop the cable over a Tiger Moth towing a glider off the main runway. It caught round the propellor.The teenage winch operator had no guillotine - just an axe. He hacked through the cable as it tightened. The ex-Spitfire pilot released the glider, and successfully landed, with the cut winch cable attached to the prop. There were no injuries. I think that cable was the stranded stuff we used before pianowire. Instructors didn't need to do simulated cable breaks - they were too common.

All so familiar, good to see the amount of agreement by everyone involved in gliding.

If the cable is guillotined and the cable hung up, then the procedure is to fly a tight spiral over the field aiming to land in the centre. I know someone who did it for real once, he says it was no big drama.

Once, I did see the cable get struck by lightning before the glider released. The glider pilots were aware what had happened, but the winch driver just thought it was a cable break. However, the cable couldn't be found. It had vapourised!

Going back to the original question of the risk of the glider being unable to release the winch cable.

Clearly that would be a pretty serious situation even given the presence of cable guillotines on the winch etc.

The automatically releasing hook ("back releasing" hook) was invented pre WW II to counter this risk and as has been said, its action should be checked daily before the first flight. It's a very reliable system even if (say) the cable release knob comes off in the pilot's hand.

The remaining risk of a winch cable "hang up" these days is if at the start of a launch, after a slightly enthusiastic taking up of the slack in the cable, the glider rolls forward, runs over the cable and picks it up around the mainwheel.

This risk is countered by the last few metres of the cable ("the strop") near the glider being encased in a relatively stiff length of plastic hose. Also the launch should be aborted by the signaller if the glider is seen to overrun the cable at all prior to the "all out" signal being given to the winch driver

All these security systems have evolved over the last 90-odd years since the gliding movement took hold. The risk of a "hang up" is one of the first things an onlooker thinks about when he first sees a winch launch, but in reality the risk is now tiny (never say never)

Many years ago, I was doing a 80 nm cross-country tow with a two-seat Lark (IS-28B2) behind me. We were parallel to and about 10 miles down-wind of the Canadian Rocky Mountain Front Ranges on a wave day.

It was quite rough, so we were using a long rope. About half-way, our CFI, who was flying from the back seat of the Lark, called me up and said incredulously "We're off tow!". Sufficient slack had developed to cause the Tost hook to back-release.

I'll draw a veil of the subsequent field landing and takeoff, other than to say there was no damage, except for grass stains on the belly of the tow-plane - a C182 Lawnmower. :E

The moral of the story was that we subsequently disabled the back-release, since we only aero-towed.

A lot of gliders have two hooks. They are all made these days (and for many years) with a CoG hook for winching, some have an extra hook added further forwards for aerotow as a/t on a CoG hook can be 'interesting'. (in some cases the a/t hook is right in the nose)

Some older gliders have a compromise hook which does neither that well.

The a/t hooks usually don't have a back release, though the one in my glider does.

Was there no training at all for a winch driver!? True, a glider pilot can abort the launch by dumping the cable if he is unhappy, but will a student pilot reliably do so? Also, one can do a little bit of damage driving a winch beside that. I have heard about bicyclists on a road beside the glider strip getting caught straight off their bike by the cable parachute after the winch driver failed to pull in the falling rope sufficiently fast; another one removed a fence post or two. So there surely must be some insurance requirement around. Also, who teaches the winch driver to splice a broken cable, handle the various malfunctions and - not to forget - drive the often rather rustic truck the winch is mounted upon? A 1960s truck with a non-synchronized gearbox and pneumatic brakes is a bit different from todays cars most people are used to: an uninitiated person would likely not even get the engine started or stopped.

In my club, every aspiring winch driver had to do 150 tows on at least 10 days under supervision of one of the nominated trainers, then pass a test consisting of 10 tows, a theoretical examination and two splices (a broken cable and an eye) with an examiner. Then, one would receive the winch license. From that moment on, one would spend half a flying day on the winch every 4-6 weeks according to schedule, and be allowed to fly not only K13 and K8, but also the plastic types.

This is what a modern glider winch looks like. Made by Skylaunch whose advertising strap-line is, 'Its like going up on rails.'

http://www.skylaunchuk.com/images/evo1.jpg

And it taught me not to stick my tongue out during take off.

Bitten tongue bleeds a lot.

Aerotow on CG Hook
 

It does require just as much attention behind a towplane as a winch when close to the ground as a cartwheel is very bad news.

Once you have 50' I find it easier in my 27 (70% CG) with a CG hook than the K-21, even when the towpilot takes a thermal. A forward hook produces a yaw couple in turns that requires compensation with rudder.

The 20 with 80% CG is considerably more frisky;)

RBF
Agree that aerotow also requires attention. I have a '20' which does not have a nose hook, so aerotowing is a little tricky, particularly in the initial ground run as there is not a lot of aileron authority. I use full, negative flap up to 25 kts which gives a bit more authority but she still wants to drop a wing especially in nil-wind conditions - much course stick input needed. At 25kts, flaps are brought back (carefully) to zero and off we go. I think the big difference in wing drop on winch is the rapidity at which it can occur if you get a snatched launch.

I had a K6E that has an offset to the left belly hook. Aerotows could be very interesting! It would attempt to ground loop as soon as the tug moved, lots of left everything and stay awake!!

Definitely BEWARE when accepting a winch cable in your glider, your hand MUST be on the release because if a wing drops and the glider cartwheels there have been fatalities and the poor basket never even got off the ground.

Winch cables are bloody dangerous. To spectators, passersby, and to power planes that ignorantly fly over a gliding site. One power pilot departed our airfield after visiting (we think) a local pub, and he flew through the wire as a glider was being launched; why his wing didn't get sawed off I will never know. The pillock should have landed immediately. Instead of which he blithely flew back to Wellesbourne. I wonder how he explained the damage to the flying club?

Neighbouring our gliding site is a very active karting circuit. Wind may blow cables over the track....so we have to choose a different runway and accept a crosswind.

I learned to fly at Booker, on aerotow, then moved to Shenington near Banbury and used to be totally freaked out by winch launching. The acceleration is astonishing. But I did get used to it, and ended up as an instructor having to teach winch launching. This never fails to bring out the sadist in the instructor (me too!) because when the pupil is getting near solo, he will have a LOT of practice winch failures. The instructor tries to be as sneaky as possible before pulling the release.

My favorite way of making the pupil suffer was to tell him that on the next launch we would have a practice launch failure.

And then I wouldn't. All the way to the top of the launch, maybe 1,200 or 1,400 feet, the poor guy is expecting the "BANG!" of the simulated cable break, most likely at the most awkward height for what do you do next! and it doesn't happen.

The lesson is it COULD happen at any moment, so one should be ready and have a plan of action ahead of time.

We used to winch using piano wire, and that was horrid for the poor winch driver, it frequently broke, and descended over the cab of the winch like spaghetti. Best thing for the pilot to do in this case was to soar for at least an hour until he got over it!

I was a towplane pilot, so declined to learn to drive the winch, at my age I shouldn't be having to wrestle splicing the braided steel cable we use now. We considered using the fancy new plastic line called Dynema, but it lays out on the top of the grass when taken to the glider, and is much more likely to be picked up if a glider or car or whatever has to cross over the wire. Which you do not do if it is at all likely to be suddenly in use.

The new winches are very simple, I am told. We used to employ a retired and possibly classic German Fire Engine converted into a winch that served us well for years.

Some clubs use a light signal. We use radio to the winch; once the glider lifts into the air, the winch driver is keeping an eye on it, and if you need to call STOP (anyone can do this if they see danger) he would not be looking at the light. Paddles were used in the olden days.

The drill for the wingtip holder, who MUST be trained and alert, is to carefully look around above and behind and in front in case there are gliders soaring over the winch. If OK to go, he levels the wings. Then naming which cable is being used, he says
"Launch to winch, K13, Take up Slack!" The winch driver stops reading his magazine, starts the engine, and slowly draws in the cable until the wingtip holder (or whoever is doing the radio) says and signals with his OTHER arm
"ALL OUT ALL OUT!!" The winch driver floors the throttle and the glider accelerates incredibly fast, rotates when it is safe to do so, and goes for the ride up the wire.

We know the back release works, we test it first launch every day. There are different weak links on the cable according to the weight of the glider.
Red, Blue, or Black. And we hope that the winch driver knows how to use the guilllotine......

though I know of no time when it has been used! except by mistake.

If the glider is then dragging the cable, and can't drop it, it probably wont make all that difference to the performance if he keeps his speed up when turning toward the pre-selected landing spot. If it drags over a fence or trees, that probably won't yank very much....I've done it with a tow plane.

Any questions?