On an early flight the first thing the instructor demonstrated to me after the takeoff was the effect of different glider positions behind the tow plane or 'tug'.
When being towed, the glider has to be flown in a tight formation with the tug, following its every move, banking and rising or and falling with the tug as it rides the air, especially in any turbulence (more common nearer the ground). This is rather like riding as a passenger on a motor bike, following the body movements of the driver.
The instructor showed me how the glider reacts in different positions. Normally the glider is positioned almost directly behind the tug - to be precise, a little above its extended centreline. Too low and the glider enters the turbulence created by the wash of the tug's propellers. The effect of the prop wash is very clear. It can make the glider very hard to fly accurately. Too high and the stability of the tug is threatened. If the tug's tail is pulled up it can stall and dive - very dangerous near the ground. Alternatively the glider can be flown lower than the turbulent wake of the tug where the air is smoother again. This is common in other countries, especially Australia. But the high tow position is preferred here. You don't need to descend through the prop wash after the takeoff, and you can keep an eye on surrounding fields in case you have to land out.
A few flights later as we reached 1,000 feet the instructor decided to teach me "boxing the tow".
This is a practice drill to check that you can put the glider where you want it to be behind the tug - and that you can correct an out-of-position situation that develops during the tow. If you get into a bad position, you or the tug may have to abandon the tow which is troublesome when you are still near the ground. The boxed tow is performed either to the left or the right or all the way round (i.e. a square path around the tug's slipstream missing it completely).
I was shown a left-hand box. The instructor steadied us in the standard towing position, a little lower than the tug plane, but still above its extended centre-line (as the tug is climbing nose high), keeping us just above the prop wash. Then he flew us slowly down through the turbulent slipstream into the 'low tow' position. Bumpy. After a pause he moved us sideways to the left and paused, then climbed us back up level with the towing position but still out to the left. Finally he slid us back again into the standard towing position.
And then it was my turn. Suffice to say, I managed a sort-of box-like-shape accompanied by a lot of waggling on the controls and a few beads of sweat on the brow. The added ingredients of the rope pivoting the nose towards the tug, the tug's turbulent wake, and the high speed of the tow (heavy ailerons, light elevators) made the manoeuver a bit harder than I expected. Flying the tow is quite different to flying normally.
A week or so later, again around 1,000 feet, the instructor asked me to box the tow again. This attempt was a little more stable than the first, but when I descended to the low tow position I was a bit hasty and accelerated too fast towards the tug. The tow-rope went very slack and bowed out alarmingly to the side and almost behind us. I could now see more of the side of the tug than the rear. I saw the tug pilot casting a wary eye over us and waving us back. The instructor helped me a little to move us back into the right position again.
This reminded me that when manoeuvering behind the tug it is important to use small deliberate movements, freezing them regularly to make sure you do not overdo it, especially when climbing or descending.
By my third attempt at boxing the tow (flight twenty-something) I was finding it somewhat easier.