Keeping straight is easy - just stop it from turning!

Beginners are often frustrated because the glider keeps wandering about in any direction but the one they want. They know they should keep the wings level, but as far as they can see the wings are level. Yet experienced pilots can fly straight quite precisely even when it is impossible to judge the bank angle with high accuracy, such as when there is no horizon, or when surrounded by local hills whose horizon is anything but level or regular. What is the secret of their success? Probably they will tell you that they keep their wings level. This is of course the mechanism that keeps the glider striaght and is the end result of their actions, but it is not in fact how they do it.

No pilot has any difficulty in noticing when turbulence tips a wing up a few degrees or in getting the wings back approximately level again. The problem arises from the much subtler cues involved in maintaining precision straight flight in smooth conditions. It is surprising how quickly the heading changes when the bank angle is very small. At 40 knots a 1° bank angle generates a turn rate of about half a degree per second, so after only ten seconds the heading has altered by 5°. The wing tips are only a few inches higher or lower than they should be, which can be pretty hard to spot visually and impossible to sense physically. On the other hand, the heading error is easy to spot, at least once the beginner has become able to orient him/her/self.

If the glider turns off the required course, you respond to the turning, which is obvious, and not the bank angle, which is much less so. Just turn it back again.When driving a car, you don't agonise over the position of the steering wheel. You move it if you are not pointing where you want to go, and stop moving it if you are. On a well-cambered road, you don't hold the wheel straight and then wonder why you drift into the kerb.

Bank angle is the glider's steering wheel, and is merely the means to the end of a desired turn rate. When flying straight, experienced pilots apply roll control only to stop turning, and the fact that this requires the bank angle to be precisely zero is unimportant. In a straight sideslipping approach, the wings are not level, but you don't bank to a pre-specified angle. You apply whatever bank angle keeps the turn rate zero. It's the same in level flight.

So next time the glider seems to be defying the laws of nature by turning when the wings appear to be level, direct your attention to the turn itself. If you are turning, the wings are banked in the turn direction even if you can't detect it. Apply a little bank in the other direction until you stop turning. Apply a little more and so on, and you will soon be back on the required course. Keep attending to where you are pointing and you can hold the course without worrying if your wings are level. They will be. (Unless of course you are skidding too, but that's another story.)

John Gibson.

15/6/99