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launch and facilitating an aborted launch if an
unsafe condition arises.
IN-FLIGHT SIGNALS FOR GROUND LAUNCHES
Since ground launches are of short duration, in-flight
signals for ground launches are limited to signals to
the winch operator or ground vehicle driver to increase
or decrease speed. [Figure 7-15]
Figure 7-14. Winch and aerotow pre-launch signals.
Check Controls Open Towhook Close Towhook Raise Wingtip
(Thumb moves thru circle.) to Level Position
(Arm moves slowly back
and forth thru arc.)
Take Up Slack Hold Begin Takeoff!
(Arms straight out and held steady.) (Arm makes rapid circles.)
(Wave arms.) (Draw arm across throat.)
Stop Operation Immediately! Release Towrope or Cut Towline Now
TOW SPEEDS
Proper ground launch tow speed is critical for a safe
launch. Figure 7-16 compares various takeoff profiles
that result when tow speeds vary above or below the
correct speed.
Each glider certified 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.
Glider pilot yaws glider repeatedly to signal
ground operator to reduce tow speed.
Glider pilot rocks wings to signal
ground operator to increase tow speed.
Figure 7-15. In-flight signals for ground launch.
Tow Speed Correct: Glider climbs to altitude safely.
Tow Speed Too Fast: Glider cannot raise nose to climb because doing so would exceed maximum permitted
ground launch airspeed.
Tow Speed Too Slow: Glider cannot climb because it is not possible to achieve safe margin above stall speed.
Figure 7-16. Ground launch tow speed.
7-13
7-14
AUTOMOBILE LAUNCH
During automobile ground launches, the glider pilot
and driver should have a thorough understanding of
what ground speeds are 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 so as not to exceed this maximum
vehicle ground tow speed.
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 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 speed 75 MPH
1. Surface winds 10 MPH 65 MPH
2. Airspeed increase during climb
5 MPH 60 MPH
3. Estimated climb wind gradient
5 MPH 55 MPH
4. Safety factor of 5 MPH 50 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
only about 20 percent of the power is needed. As the
glider reaches the 70° point above the horizon, the
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 7-17]
NORMAL INTO-THE-WIND GROUND 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 hook-up 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
towrope 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 the
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Glider Flying Handbook(63)
