Normal Into-the-Wind Launch
Normal takeoffs are made into the wind. Prior to launch, the glider pilot, ground crew, and launch equipment operator must be familiar with the launch signals and procedures. When the required checklists for the glider and ground launch equipment have been completed and the glider pilot, ground crew, and launch equipment operator are ready for takeoff, the glider pilot should signal the ground crewmember to hook the towline to the glider. The hookup must be done deliberately and correctly. The release mechanism should be checked for proper operation. To accomplish this, the ground crewmember should apply tension to the towline and signal the glider pilot to activate the release. The ground crewmember should verify that the release has worked properly and signal the glider pilot. When the towline is hooked up to the glider again, the ground crewmember takes a position at the wingtip of the down wing. When the glider pilot signals “ready for takeoff,” the ground crewmember clears both takeoff and landing areas. When the ground crewmember has ensured the traffic pattern is clear, the ground crewmember then signals the launch equipment operator to “take up slack” in the towline. Once the slack is removed from the towline, the ground crewmember again verifies that the glider pilot is ready for takeoff. Then, the ground crewmember raises the wings to a level position, does a final traffic pattern check, and signals to the launch equipment operator to begin the takeoff.
CAUTION: Never connect a glider to a towplane or towline unless the pilot is aboard and ready for flight. If the pilot exits the glider for any reason, the towline should be released and disconnected. Glider pilots should be prepared for a takeoff anytime the towline is attached to the glider.
The length, elasticity, and mass of the towline used for ground launching have several effects on the glider being launched. First, it is difficult or impossible to prevent the glider from moving forward as the long towline is tautened. Elasticity in the towline causes the glider to creep forward as the towline is tightened. For this reason, the towline is left with a small amount of slack prior to beginning the launch. It is important for the pilot to be prepared for the launch prior to giving the launch signal. If the launch is begun before the pilot gives the launch signal, the glider pilot should pull the towline release handle promptly. In the first several seconds of the launch, the glider pilot should hold the stick forward to avoid kiting. During the launch, the glider pilot should track the runway centerline and monitor the airspeed. [Figure 7-21, position A]
When the glider accelerates and attains lift-off speed, the glider pilot eases the glider off the ground. The time interval from standing start to lift-off may be as short as 3 to 5 seconds. After the initial lift-off, the pilot should smoothly raise the nose to the proper pitch attitude, watching for an increase in airspeed. If the nose is raised too soon or too steeply, the pitch attitude is excessive while the glider is still at low altitude. If the towline breaks or the launching mechanism loses power, recovery from such a high pitch attitude may be difficult or impossible. Conversely, if the nose is raised too slowly, the glider may gain excessive airspeed and may exceed the maximum ground launch tow speed. The shallow climb may result in the glider not attaining planned release altitude. If this situation occurs, the pilot should pull the release and land straight ahead, avoiding any obstacles and equipment.
As the launch progresses, the pilot should ease the nose up gradually [Figure 7-21, position B] while monitoring the airspeed to ensure that it is adequate for launch but does not exceed the maximum permitted ground launch tow airspeed. When optimum pitch attitude for climb is attained, [Figure 7-21, position C] the glider should be approximately 200 feet AGL. The pilot must monitor the airspeed during this phase of the climb-out to ensure the airspeed is adequate to provide a safe margin above stall speed but below the maximum ground launch airspeed. If the towline breaks, or if the launching mechanism loses power at or above this altitude, the pilot has sufficient altitude to release the towline and lower the nose from the climb attitude to the approach attitude that provides an appropriate airspeed for landing straight ahead.
As the glider nears its maximum altitude [Figure 7-21, position D], it begins to level off above the launch winch or tow vehicle to reduce the rate of climb. In this final phase of the ground launch, the towline is pulling steeply down on the glider. The pilot should gently lower the nose of the glider to reduce tension on the towline and then pull the towline release two to three times to ensure the towline releases. The pilot feels the release of the towline as it departs the glider. The pilot should enter a turn to visually confirm the fall of the towline. If only a portion of the towline is seen falling to the ground, it is possible that the towline is broken and a portion of the towline is still attached to the glider.
If pulling the tow release handle fails to release the towline, the back release mechanism of the towhook should automatically release the towline as the glider overtakes and passes the launch vehicle or winch.
Climb-Out and Release Procedures
The pitch attitude/airspeed relationship during ground launch is a unique flight experience. During the launch, pulling back on the stick tends to increase airspeed, and pushing forward tends to reduce airspeed. This is opposite of the normal pitch/airspeed relationship. The wings of the glider divert the towing force of the launch vehicle in an upward direction, enabling rapid climb. The greater the diversion is from horizontal pulling power to vertical lifting power, the faster the airspeed is. This is true if the tow vehicle is powerful enough to meet the energy demands the glider is making on the launch system.
Common errors in ground launching include:
- Improper glider configuration for takeoff.
- Improper initial positioning of flight controls.
- Improper use of visual launch signals.
- Improper crosswind procedure.
- Improper climb profile.
- Faulty corrective action for adjustment of airspeed and pitch.
- Exceeding maximum launch airspeed.
- Improper towline release procedure.