Secondary Effect of Ailerons

Secondary effect of ailerons is adverse yaw.

In this lesson, we will demonstrate the secondary effect of the ailerons.

Learning Points

We have seen already that the ailerons are used to roll the glider. The instructor cheated a little in the previous demonstration, as she was applying a co-ordinating rudder movement. What happens if we use the ailerons on their own? It depends to some extent on how quickly we are flying.

When flying slowly, and rolling without rudder, the glider will initially yaw markedly in the opposite direction as it slips into a badly coordinated turn in the direction of the roll (watch the string flick away from the turn!). This effect is called ‘adverse yaw’ and is a result of aileron drag on the upgoing wing.

When flying more quickly and rolling without rudder, the yaw effect is less marked, but a sideslip will be seen in the turn (check the string).
If we use the aileron and rudder together, we can make a coordinated turn, meaning there is no yaw as we turn. This is confirmed by seeing the string point backwards at all times

Demonstration Scenario

This demonstration is in a valley, in calm conditions, flying a Standard Cirrus. This is not the way to fly! Your goal is always to fly ‘coordinated’, using matching aileron and rudder movements together.

Secondary effect of ailerons

The video is best viewed in YouTube in HD in Full Screen mode, to easily see the on-screen messages and instruments during the demonstration. Use view, pause and rewind as needed to grasp the content and timing of the messages displayed, then focus on the action.

Further Reading and References

Gliding From Passenger to Pilot, 2nd Edition: Pages 35-36, 88

BGA Instructors’ Manual, 4th Edition: Section 2, Chapter 7, Page 7-3

BGA Instructors’ Reference Cards: Ex 6

BGA Gliding Basics – Effects of Controls