The Straight Glide

The objective of this lesson is to achieve the straight glide. Having said glider pilots spend a lot of their time going round in circles, we need to be skilled at flying straight, between thermals, back to the airfield, or around the circuit. It sounds simple doesn’t it – so why does it follow learning to turn? Well, the air around us is rarely still – it will be continually affecting us in three dimensions, rather spoiling the trouble-free straight glide.

Learning Points

Flying straight to our target is important because we are losing height most of the time, and so we want to reach the next source of lift, or progress cross country with the least possible loss of height. The shortest route will be a straight line.  Flying straight is also essential when making an approach to a landing area, especially so when you must land on a narrow runway, or in a confined area.

We know we are flying straight when

• the wings are level,
• the string is straight back and
• our target does not move across the canopy – it will only be straight ahead in still air, or directly into wind or downwind. In a cross wind it will be off to one side, as we crab towards it.

We fly straight by making small adjustments to maintain the attitude. It’s important to realise that the glider is quite stable, and if, in trim, you take your hands off the controls, it will continue to do pretty much the same as before for a while. The air will be moving around us, and it will tip the glider into a descending turn sooner or later. So, the trick to flying straight is to counter the tendency to be knocked off course, by making coordinated use of all three controls.

The method

• Set the attitude and trim for the glider’s best L/D
• Check the wings are level, the string is straight, and the target isn’t moving across the canopy.
• Adjust with coordinated use of all three controls, and settle into balanced flight*
• Check the ASI, and one other (relevant) instrument: Altimeter if you need to check you have the height to reach a safe landing area, or the Vario if you are looking for lift, or your GPS if navigating to a waypoint or near airspace
• Perform the Scan Cycle, as described in Lesson 4b
• Repeat

This is often summarised as Lookout, Attitude, Instruments.

*Note: In reality, there is some subtlety here. If the bank changes without a change of aileron then the glider tends to slip down the lower wing and the string moves. Pupils who have been taught that we always keep the string straight with the rudder do so and find that they are in a manoeuvre they didn’t intend. In level flight this leads to the Dutch roll and in a thermal, usually, an increasingly tighter and faster turn. The reality is that when manoeuvring we use the rudder (without moving the stick) to centre the string but once we have manoeuvred we (promptly) use the stick to restore the chosen bank (without using the rudder).

Scenario and Demonstration

This demonstration and exercise will be in still air. You’re flying the Standard Cirrus. We are heading North West towards the river and small lakes at the top of the valley. Starting on track, the demonstration first shows the effect of letting go of the controls for a while, then continues by making small adjustments to stay on track.

Alternative Video without animation

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 to go 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 the this exercise, you’re ready for some turbulence.

Further Reading and References

• Gliding From Passenger to Pilot, 2nd Edition: Pages 87-88
• BGA Instructors’ Manual, 4th Edition: Section 2, Chapter 9
• Gliding: The British Gliding Association Student Pilot Manual, Section 4.6 and website.