4. LESSON 10 - THE AIRBRAKES
- Opening the airbrakes leads to a decrease in airspeed and increase in vertical speed (slower speed, faster descend)
- Maintain the correct airspeed with the control stick and control the glide path with the airbrakes
- When you open the airbrakes, the glider’s nose should go further below the horizon
- Keep holding the airbrakes lever to maintain the desired amount of airbrakes
In this exercise you will learn about the effect of the airbrakes. Gliders have a long range; a "glide ratio" of 1:40 is not uncommon. This means that your range is about 40x your height. If you’d enter your airfield at 300 feet and you wouldn’t use your airbrakes, you wouldn't be on the ground until approximately 2.5 miles later. Most airfields are not that long and no other type of aircraft has such an incredible performance. Thanks to the airbrakes, we can land exactly where we want to.
USING THE AIRBRAKES
The airbrakes lever is coloured blue in every glider. When you pull the lever, the airbrakes open. The further you open them, the more air resistance (drag) they provide. If you push the lever all the way forward, you can feel and hear the lever going through a lock; after that they will remain closed. In many training gliders, the airbrakes lever is combined with the wheel brake. If you keep pulling the lever with fully opened airbrakes, you also operate the wheel brake.
It is important to keep holding the airbrakes lever when you operate the airbrakes. If you let go, they will not remain in the desired position, and they might even suck completely open. You can only stop holding the airbrakes lever when the lever is in the locked position.
During this lesson, you will start flying at a normal landing airspeed. Use the trimmer to maintain the corresponding pitch attitude. After setting the trimmer, you will not need it again during this exercise. Open the airbrakes with your left hand. You will see a small decrease in airspeed and an increase in vertical speed. Close the airbrakes and repeat the first exercise, but now try to maintain the desired airspeed using the elevator. You will see that when you open the airbrakes this time, you will have to push the stick slightly forward to move the nose a little further down, below the horizon (a lower pitch attitude). If you reduce the amount of airbrakes, you will see that the speed will increase and that you will have to adopt a slightly higher pitch attitude (pull the stick backwards) to continue flying at the desired airspeed. Finally, try to operate the airbrakes over their entire range, from closed to fully opened and back again, while using the stick to remain a constant speed.
The airbrakes create variable amounts of additional drag. They make it possible to land exactly where you want to land.
Lesson 24 discusses the use of the airbrakes at higher airspeeds.