Glider towing limitations question
Join Date: Jan 2009
Location: Oxford, UK
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John Mariott has written a fairly comprehensive book on tugging, I recommend it (as he asked my advice while writing it!}
In the UK the weaker link is at the glider, the slightly stronger one at the tug.
I found myself pushing a rope once that hadn't been correctly fastened to the tug, while flying with a student; this happened about 220 feet on a nil wind day climbout, so we were fairly far from the airfield already, so I took control (when in doubt there is no doubt), turned and had a look and we managed to return and land in a corner of the airfield; dropped the rope before crossing the hedge, and it took 5 hours to find the blame thing - kept imagining it all wound up in the combine harvester....
The student grumbled, he said HE could have done the return! I said, yes, but I wasn't sure I could do it!
We think it quaint that the Australians insist on flying the curious low tow, giving another set of problems early in the launch. Here in the UK, the glider lifts off gently with flying speed, waits for the tug to begin the climb, and then with the TUG POSITIONED CORRECTLY ON THE CANOPY OF THE GLIDER, carries on following NOT TOO HIGH, but above the slipstream. Low tow and boxing the wake are exercises in skill and recovering from oscillation, etc.
Reason we teach tug position on the canopy, rather than the picture of the tug wings on the horizon, Backpacker, is that we sometimes fly in mountains, or possibly with clouds etc obscuring the picture. Flying up into a nice big ridge at Talgarth, in Wales, how on earth could you check your relative position by tug wings on the horizon?
But the big no no is DON'T PULL UP HIS TAIL! That's how to kill a tug pilot. Brian Spreckley and Chris Rollings practiced upsetting tugs at 6,000 feet or so, and it takes the tug at LEAST 2,000 feet to recover. Trouble is, especially with a belly hook on the glider, or too short a rope or too stupid a glider pilot, is that it is likely to happen lower than that. The tug plane is in effect suspended from the glider until the rope breaks, WITH NO FORWARD SPEED AT ALL! It is not in a dive, it is STALLED!
So first of all, training new pilots to fly the glider on airtow, make sure they can hold position correctly, recover from every kind of oscillation, and when in doubt, let go. Tuggies, your left hand should be very very near the rope release handle. And if in doubt, dump him!
New tug pilot at our field forgot he had a rope on the back, and pulled up 3 fenceposts with barb wire attached. Didn't damage the aircraft. The farmer - who always turned up when somebody did something stupid, presented him with a post hole digger and he had to spend the rest of the afternoon mending the fence......
In the UK the weaker link is at the glider, the slightly stronger one at the tug.
I found myself pushing a rope once that hadn't been correctly fastened to the tug, while flying with a student; this happened about 220 feet on a nil wind day climbout, so we were fairly far from the airfield already, so I took control (when in doubt there is no doubt), turned and had a look and we managed to return and land in a corner of the airfield; dropped the rope before crossing the hedge, and it took 5 hours to find the blame thing - kept imagining it all wound up in the combine harvester....
The student grumbled, he said HE could have done the return! I said, yes, but I wasn't sure I could do it!
We think it quaint that the Australians insist on flying the curious low tow, giving another set of problems early in the launch. Here in the UK, the glider lifts off gently with flying speed, waits for the tug to begin the climb, and then with the TUG POSITIONED CORRECTLY ON THE CANOPY OF THE GLIDER, carries on following NOT TOO HIGH, but above the slipstream. Low tow and boxing the wake are exercises in skill and recovering from oscillation, etc.
Reason we teach tug position on the canopy, rather than the picture of the tug wings on the horizon, Backpacker, is that we sometimes fly in mountains, or possibly with clouds etc obscuring the picture. Flying up into a nice big ridge at Talgarth, in Wales, how on earth could you check your relative position by tug wings on the horizon?
But the big no no is DON'T PULL UP HIS TAIL! That's how to kill a tug pilot. Brian Spreckley and Chris Rollings practiced upsetting tugs at 6,000 feet or so, and it takes the tug at LEAST 2,000 feet to recover. Trouble is, especially with a belly hook on the glider, or too short a rope or too stupid a glider pilot, is that it is likely to happen lower than that. The tug plane is in effect suspended from the glider until the rope breaks, WITH NO FORWARD SPEED AT ALL! It is not in a dive, it is STALLED!
So first of all, training new pilots to fly the glider on airtow, make sure they can hold position correctly, recover from every kind of oscillation, and when in doubt, let go. Tuggies, your left hand should be very very near the rope release handle. And if in doubt, dump him!
New tug pilot at our field forgot he had a rope on the back, and pulled up 3 fenceposts with barb wire attached. Didn't damage the aircraft. The farmer - who always turned up when somebody did something stupid, presented him with a post hole digger and he had to spend the rest of the afternoon mending the fence......
