This lesson demonstrates that stalls will occur with the wings level after entering a high speed climb if you hold the attitude. This is the situation you’ll find yourself in as a result of a failed winch launch, or misjudging a climbing turn into a thermal, or perhaps just messing about burning energy.
- Speed decays rapidly in a steep climb.
- The resulting stall will occur with the nose high, but possibly without warning from a pre-stall buffet, or a high sink rate for instance. These stalls will occur in the absence of most symptoms – you must recognise the attitude cannot be held for long, and react accordingly.
- Holding the stick back will not keep the nose up.
- Moving the stick further back, if possible, will not raise the nose.
- The nose will drop quickly, possibly with wing drop.
- Relaxing the back pressure on the stick won’t save this situation: you must move the stick well forward to regain speed, then recover the attitude.
- The first move is to move the stick forward centrally. Only raise the lower wing when you have the speed to do so.
- The nose will drop considerably, and hence you will lose more height than in an unaccelerated stall. Not a good thing to do close to the ground.
Scenario and Demonstration
This demonstration shows the glider in level flight, slowing until the pre-stall buffet. This is at around 37kts for the unaccelerated stall. Easing the back pressure on the stick is enough to avoid the stall.
We then speed up to 50kts or more and enter a climb of around 30 degrees. The speed decays quickly but we hold the attitude to see what happens next. The stall occurs quickly, and we push the stick well forward, to get the speed we want to recover. Speed will build rapidly… when the speed is sufficient we then bring the wings level and enter a climb to regain some lost height, before levelling out as the speed decreases again.
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
Start by confirming the speed at which you see pre-stall buffet in level flight. Then speed up to 50kts or more and climb, wings level, holding the nose up at about 30 degrees. As you’re not trimming during this exercise, you’ll probably require more pressure than usual to hold the attitude. Wait. And recover. We will revisit this area for winch launch failures, when both the speed and nose up attitude can be higher.
The sim is a great place to practise these exercises.
Further Reading and References
Gliding From Passenger to Pilot, 2nd Edition: Page 94-95
BGA Instructors’ Manual, 4th Edition: Section 5, Chapter 18