User manual

Aerosoft PBY Catalina 1.00 Manual
Page 14 of 100
Engaging the autopilot
Engaging the autopilot required that vacuum was present for the gyros. The suction pressure could
be checked on the suction gauge on the autopilot unit. The necessary hydraulic pressure was
supplied from the Catalinas right engine (or aux. electrical hydraulic pump). Supply of hydraulic
pressure was controlled by the “Master Autopilot” control lever, mounted in the roof, behind the
throttle quadrant. Pressure could be read on a gauge on the autopilot control unit. This gauge also
indicated if the autopilot was active or not. The Sperry autopilot is active when suction pressure is
higher than 2 inHg and the hydraulic pressure gauge reads more than 105 Psi, controlled by the
“Master Autopilot” lever. Engaging the Sperry autopilot by setting the “Master Autopilot” lever to
On, doesn´t mean that it will control the aircraft, but only that the various modes can be engaged via
the gain knobs.
Gain settings
Actual hydraulic pressure for moving the controls was supplied through proportional flow valves,
mounted on the lower part of the Sperry autopilot unit. These valves where used for controlling how
fast the actuators should react, and could be adjusted gradually. Turning these knobs to low values
helped dampening autopilot control. The knobs where called “Rudder gain”, “Elevator gain” and
“Aileron gain”. Be aware that the higher the gain setting, the more “nervous” the autopilot
becomes! Open the valves slowly until the aircraft starts to get “nervous” – then close the valves
again just a little. Heading hold was only becoming active if the actual heading was within 10° of the
selected heading. The pilot had to turn the aircraft until it was within ±10° of the selected heading
set with the “Rudder” knob, before engaging heading hold, which was done by opening the “Rudder
gain” knob.
Heading
The selected heading was read on the upper “compass” scale, while the actual heading was read on
the lower “Gyro compass” scale. Since the gyroscope would drift over time, the pilot needed to
adjust the gyro compass with the gyro compass align knob. The autopilot had no altitude hold
function, but could hold pitch. To use pitch hold the pilot had to set the engines to either climb,
cruise or descend settings and level the aircraft.
Pitch
Engaging pitch hold was done by opening the “Elevator gain” knob. The pilot could now adjust the
pitch with the “Elevator” knob, to make the aircraft fly with a certain vertical speed or keep it level.
Be aware that as fuel was burned and the aircraft became lighter, the aircraft would start to climb.
Also changing the engines’ settings would make the aircraft start to climb or descend.
The selected pitch could be read on the pitch reference indexer on the right side of the attitude
indicator gauge. Once the aircraft was established on the desired pitch, the horizon bar should
coincide with the pitch reference indexer, when flown un-banked.