Figure 4-18.-Catapulting system control and indicating system.
Placing the launch bar control switch in
weight-on-gear switch moves to the weight-off
EXTEND completes a power circuit through the
position. This applies 28-volt dc to the launch bar
weight-on-gear switch, applying 28-volt dc to the
selector valve retract solenoid (solenoid B) and to
launch bar selector valve extend solenoid (solenoid
the launch bar warning light through the energized
A). The launch bar valve position switch also
contacts of relay K1. K1 remains on until the
completes a circuit through its closed contacts to
launch bar is up and locked. Power to the launch
apply 28-volt dc to the launch bar warning light.
bar selector valve retract solenoid provides
The warning light comes on and remains on as
automatic hydraulic retraction and locking of the
long as the switch is in EXTEND. When the
launch bar after catapulting. The launch bar
selector valve actuates, hydraulic pressure extends
actuating cylinder, locking in the fully retracted
the launch bar actuator. A plunger on the end of
position, de-energizes K1, turning off the launch
the valve mechanically actuates the launch bar
bar warning light. The approach light circuit
valve position switch. Switch actuation completes
goes through de-energized relay K1, giving an
a parallel circuit to the warning light. When the
additional indication that the launch bar is up and
locked.
control switch is in the OFF position, with weight
on the landing gear, the warning light should go
The launch bar control switch goes to
off. If the control switch is in RETRACT, the
RETRACT and is held thereto retract the launch
warning light should come on until the launch bar
bar hydraulically. This completes a power circuit
is up and locked. If the light remains on, the
to apply 28-volt dc to the launch bar selector valve
selector valve did not cycle from the bar extend
retract solenoid (solenoid B). The energized
position, and pressure is still on the launch bar
selector valve directs hydraulic pressure to retract
the launch bar. The control switch returns to OFF
actuator extend side.
when released, de-energizing the selector valve.
The hydraulic pressure to the launch bar
actuator unlocks locking fingers inside the
Speed Brake System
actuator and extends the actuator to lower the
launch bar. As the locking fingers unlock, they
close the contacts of the launch bar up-lock
Speed brakes are moveable control surfaces
switch inside the actuator. After catapulting, the
used for reducing the speed of aircraft. Some
