Before the airplane reaches the catapult, the tension
extended and retracted during taxiing. The launch bar is
and holdback bars are attached to the tension bar
automatically retracted after catapulting. A launch bar
socket. As the airplane approaches the catapult, the
warning light on the main instrument panel comes on
launch bar enters a track that permits the bar to steer the
any time the following conditions exist:
nose gear for alignment with the catapult.
The launch bar control switch is in EXTEND.
The top of the launch bar actuating cylinder is
The selector valve is in bar extended position.
gimbal-mounted to permit rotation in all directions as
The launch bar is not up and locked with weight
the launch bar turns and is raised and lowered. As the
airplane moves forward, aligned with the catapult, the
off the landing gear.
launch bar automatically engages the catapult shuttle.
The launch bar control switch is in RETRACT
The shuttle is advanced to tension the airplane on the
and the launch bar actuator is not up and locked.
catapult.
Accessories for the catapulting system include a
The launch bar switch is placed in OFF,
tension bar and a catapult holdback bar. The catapult
de-energizing the selector valve. When catapult
tension bar socket is mounted on the nose gear axle
pressure reaches a predetermined value, the tension bar
beam and provides for attachment of the tension bar for
breaks and the airplane is catapulted off the deck.
tensioning of the airplane prior to catapulting.
In the de-energized position, the selector valve
The catapult system, shown in figure 15-10, is
connects the launch bar actuator extend and retract
selected to extend by placing the launch bar control
ports to the hydraulic return circuit. The launch bar is
switch in the cockpit to the EXTEND position. With
held in the down position by the catapult shuttle until
weight on the gear, this action completes an electrical
reaching the end of the launch run, where the bar is
circuit to energize solenoid A of the launch bar selector
released from the shuttle and the weight-on-gear switch
valve. The energized selector valve directs hydraulic
is actuated to the weight-off-gear position. When the
system pressure to the launch bar actuating cylinder
switch is activated to the weight-off-gear position, a
extend port. Hydraulic pressure unlocks locking fingers
power circuit is completed to energize the retract
in the launch bar actuating cylinder and extends the
solenoid of the launch bar selector valve. The energized
actuator rod end. The actuator rod end is attached to the
valve directs hydraulic pressure to retract the launch bar
launch bar, and as the actuator extends, it lowers the
actuating cylinder, automatically retracting and locking
launch bar. As the launch bar moves down, it encloses
the launch bar. Two leaf springs on each side of the
two horns on the nose gear axle beam, enabling the
launch bar shank raise the launch bar to the retracted
launch bar to steer the nose gear.
position if automatic hydraulic retraction fails. When
Figure 15-10.--Catapult system hydraulic schematic.
15-11
