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Each glider certificated for ground launch operations has a placarded maximum ground launch tow speed. This speed is normally the same for automobile or winch launches. The glider pilot should fly the launch staying at or below this speed to prevent structural damage to the glider during the ground tow. 

## Automobile Launch 

Automobile launches today are very rare. During automobile ground launches, the glider pilot and driver should have a thorough understanding of the groundspeeds to be used prior to any launch. Before the first launch, the pilot and vehicle driver should determine the appropriate vehicle ground tow speeds, considering the surface wind velocity, the glider speed increase during launch, and the wind gradient encountered during the climb. They should include a safety factor to avoid exceeding this maximum vehicle ground tow speed. 

If a crosswind condition is present, the glider should be positioned slightly downwind of the takeoff heading and angled into the wind to help eliminate control problems until sufficient airspeed is obtained. Due to the slow acceleration of the glider during an automobile ground launch, the towline should be laid out to allow the glider to obtain sufficient speed for control while still in a headwind. [Figure 7-17] 

The tow speed can be determined by using the following calculations: 

1. Subtract the surface winds from the maximum placarded ground launch tow speed for the particular glider. 

2. Subtract an additional five miles per hour (mph) for the airspeed increase during the climb. 

3. Subtract the estimated wind gradient increase encountered during the climb. 

4. Subtract a 5 mph safety factor. 

Maximum ground launch tow speed .................... 75 mph 

1. Surface winds 10 mph................................. –10 mph 

2. Airspeed increase during climb 5 mph.......... –5 mph 

3. Estimated climb wind gradient 5 mph .......... –5 mph 

4. Safety factor of 5 mph................................... –5 mph 

Automobile tow speed.......................................... 50 mph 

During winch launches, the winch operator applies full power smoothly and rapidly until the glider reaches an angle of 30° above the horizon. At this point, the operator should start to reduce the power until the glider is about 60° above the horizon where approximately 20 percent power is needed. As the glider reaches the 70° point above the horizon, power is reduced to idle. The winch operator monitors the glider continuously during the climb for any signals to increase or decrease speed from the glider pilot. [Figure 7-18] 

## Crosswind Takeoff and Climb 

The following are the main differences between crosswind takeoffs and climb procedures and normal takeoff and climb procedures: 

• During the takeoff roll, the glider tends to weathervane into the wind. 

• After liftoff, the glider drifts toward the downwind side of the runway. 

• In strong crosswinds there is a greater tendency for the glider to drift downwind. 

• If space is available in the takeoff area, the towline or cable should be laid out in a manner that the initial takeoff roll is slightly into the wind to reduce the crosswind component of the glider. [Figure 7-19] 

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