4. LESSON 14 - WINCH LAUNCHING
- Keep the wings level using the ailerons
- Left hand on the release knob
- Keep the stick neutral (do not pull backwards)
- Maintain directional control with the rudder
- Gently and gradually increase the climb angle, don’t climb steeply!
- If the cable breaks: land straight ahead
- Check your position and airspeed regularly
- In case of cable break: fly a shortened circuit or land straight ahead
- Adopt a normal pitch attitude (lower the nose)
- Pull the yellow cable release knob (two times!)
- Verify position
- Trim the glider
- Verify that the airbrakes are in the locked position and retract the landing gear
A winch launch takes you to about 1200-1500 feet above the ground in half a minute. Such an impressive launch method requires full concentration from both the pilot and the winch driver, particularly during the first seconds of the launch. Here your responses have to be quick and decisive. The trajectory of the launch follows the same pattern every time. At first, the climb angle is shallow. The higher the glider rises, the steeper the climb angle gets, until it reaches the normal climb angle (about 45° of pitch above the horizon). Due to the high pitch attitude it is hard to see the horizon by looking straight over the nose. The best way to judge your climb angle and position is by regularly looking left or right. If possible you can use a cloud as a reference point during the launch. To explain winch launching in more detail, we have divided the procedure into different phases.
During the initial acceleration, you keep the control stick in its neutral position. It is very important to keep the wings level when rolling on the ground. You do this by large deflections of the ailerons (moving the control stick left or right). Simultaneously, you make large rudder pedal inputs in order to continue on track in the direction of the winch. We make large and quick control inputs on the ground because the flight controls are not yet very effective due to the low speed. There is no need to ‘pull’ the glider off the ground, as it were; as soon as it has gained sufficient speed, the glider will lift off automatically.
If a wing drops and is about to touch the ground, release immediately! This is extremely important. If you wait and the wingtip touches the ground, it could make the glider cartwheel before you have time to release. So do not hesitate when a wing is about to touch the ground!
If you can’t keep the wings level: pull the release knob immediately before a wing touches the ground!
LEFT HAND ON THE RELEASE
Keep your left hand on the yellow release knob during the initial acceleration of the winch launch to make sure you can release the cable immediately in case of an emergency. Do not rest your hand on to the airbrakes lever or the canopy locking levers. Doing so could accidentally cause the airbrakes or canopy to open during the acceleration.
The dangers of climbing too steep at low altitudes are cable break and stall (see Lesson 23). If you exceed the critical angle of attack, the airflow will separate from the wing, the lift will decrease and the drag will increase. That is why you slowly increase the climb angle during a winch launch. As long as the airspeed remains high enough, you can always lower the nose to a normal pitch attitude in the event of a cable break.
Gradually increase the climb angle. We cannot emphasize this often enough: do not try to make steep climbs, especially in the initial phase of the launch! Most composite and modern two-seater gliders take off with the trim and stick in the neutral position. But some single-seater gliders have the tendency to automatically “over-rotate” into a steep climb just after lift-off, especially if the winch driver accelerates the cable too quickly. If this happens, push the stick forward immediately. You can also prevent over-rotating by keeping some slight forward pressure on the stick or by setting the trim slightly forward of neutral before the launch. After you have reached a greater height and the airspeed is sufficient, you can slowly increase the climb angle. It will take approximately 5 seconds before you’ve reached the desired climb angle. A guideline to help you increase the climb angle slowly is to count 21-22-23-24-25 while doing this. Avoid abrupt rudder deflections at this point, because they now increase the risk of stalling one wing (see Lesson 23). You can only return to a normal pitch attitude immediately, if the climb angle is not too steep and when you have sufficient airspeed. When you climb too steeply, you can’t lower the nose in time because your airspeed will then decrease too quickly and the glider will stall. So we will say it just once more: do not over-rotate into a steep climb!
THE PILOT IS RESPONSIBLE FOR A SAFE LAUNCH
Performing safe winch launches is a matter of experience, skills and last but not least, making the right decisions based on the actual circumstances. The winch driver estimates the airspeed; he or she cannot look inside your cockpit to see the airspeed indicator. Whenever you are launching through a wind gust or thermal, the airspeed changes. As a pilot you can see and feel the airspeed changes and – if necessary – signal the winch driver when you exceed the minimum or maximum winch launching airspeed. The procedures for this may differ. Sometimes the radio is used to signal the winch driver, but often we signal with either the elevator or the rudder. And sometimes there is just no way to communicate with the winch driver. Your instructor will make sure that you understand what the correct airspeed range is during a winch launch.
During a winch launch you need more lift than in normal flight. The wings have to support the weight of the glider plus the increased load caused by the force on and the weight of the cable. In other words, the load of the glider is higher during a winch launch. The glider cannot be overloaded as long as the maximum winch speed is observed and the correct weak link is used. Monitor your airspeed regularly. If the airspeed becomes too low, you will have to ease the pressure off the stick and clearly decrease your pitch attitude. The winch driver will see this and notice a change in the engine speed. He or she now increases the power setting for extra acceleration: your airspeed will increase and you can gradually increase your climb angle again. If you are still going too slow: release the cable.
If the airspeed becomes too high during a winch launch, you can signal the winch driver by making the glider yaw left-right several times using your rudder pedals. The signal needs to look deliberate and you may need some opposite ailerons to prevent the glider from rolling. Avoid puling the stick too much because the weak link may break. If there is no response from the winch and the glider is about to exceed the maximum winch speed, release the cable immediately.
At the final stage of the winch launch your climb rate decreases and the climb angle becomes shallower. Even though you are still pulling the stick towards you, the pitch attitude becomes lower. As a signal for you to release, the winch driver will slow or stop the winch. At this point you lower the nose below the horizon and release the cable by pulling the release knob twice. Should you forget to release, then the cable will be pulling backwards and the automatic release mechanism will be activated. Now adopt a normal pitch attitude to fly your desired airspeed. Verify your position, lookout for other traffic and trim the glider. Check if the airbrakes are still in the locked position and if possible retract the landing gear.