11
b) RECOMMENDED
SPEEDS
The recommended indicated airspeeds for attempting the various a
c
robatic manoeuvres are as follow
s
:
Indicated Airspeed
Solo Dual
knots km/hr. knots km/hr.
Loop 67
160
97
180
Stall Turn
92
170
97
180
Roll off the top
97-103
180-190
103-108
190-200
Half roll and loop
70
130
76
140
Slow roll
81
150
—
—
Inverted flight
70
130
—
—
c)
LOOP
Choose some
l
ine feature on the ground by which to keep straight during the manoeuv
r
e. From level
flight, put the sailplane into a moderate dive along the line of this feature. During the dive, do not re-trim
column. Having gained an airspeed of 87 knots (160 km
/
hr.) if flying solo or 97 knots (180 km/hr.) if
flying dual, gently raise the nose of the sailplane by slight backward m
o
vement of the control column,
taking care not to apply excessive
"g"
forces, and maintain this rate of backward stick movement
throughout the whole of the
l
oop, but not making use of more than about 60% of the control column full
travel. When the inverted position has been reached, the speed will be low and care shou
l
d be taken not
to stall the sailplane. After passing the inverted position, the control column should not be moved until
the sailplane is vertical when it should be eased forward gradually as speed increase
s
until the sailplane is
flying level again.
During the whole of this manoeuvre, rudder should be used to prevent yaw, and ailerons to keep the
wings level laterally. The stick forces required to maintain the loop decrease to a minimum at the top
when the speed is low, and increase again as the speed increases in the ensuing dive.
