The objective of this lesson is to understand how turbulence and some crosswind affects the straight glide..
Maintaining a course is more interesting when we have a cross wind, and especially so when it becomes more turbulent. Turbulence is a result of the air moving around in all dimensions – think of a shallow river flowing over rocks: whilst going in the same general direction, it can be going up, down or sideways at any particular point. The air is similar – it behaves like a liquid flowing over the landscape, with the added distraction of rising and sinking areas as it passes over patches of ground at differing temperatures. But we still want to fly straight to our target, and the goal remains the same:
- keep the wings level
- keep the string flowing straight back and
- ensure our target does not move across the canopy.
The glider remains quite stable, but will be knocked off course much more quickly. You will be making coordinated adjustments much more often, if not continuously.
Scenario and Demonstration
This demonstration and exercise will be in a moderately turbulent 20kt cross wind, amongst mountains. You’re flying the Standard Cirrus. We are heading North West towards the river and small lakes at the top of the valley. Being somewhat mountainous, the wind in the valley is quite ‘lumpy’! The glider starts on track and takes a moment to settle down. The video then shows the effect of letting go of the controls for a while, and continues by making coordinated turns to get back and stay on track. You’ll see when it is settled that we need to head slightly into wind in order to track towards our target.
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.
Performing the Exercise
Aim for the same area, choosing a specific mountain top for precision… then try letting go for while. See how long it takes for the glider to be blown off course. When it wanders off, bring it back on course and settle to the required speed, then keep your target on the nose by adjusting all three controls as necessary. When you can do this at a steady speed in this exercise, you’re doing well! Try some Free Flight in Condor with varying crosswinds and turbulence settings. Try the exercises at different speeds. Beware that in rough air it is easier to become stalled – stay safe by speeding up.
Further Reading and References
Gliding From Passenger to Pilot, 2nd Edition: Page 87-88
BGA Instructors’ Manual, 4th Edition: Section 2, Chapter 9