Autopilot (Sperry Type):
The VSKYLABS C-47 incorporates a Sperry type Autopilot with the basic C-47/DC-3 configuration of Elevator (nose attitude for pitch) and Ailerons (bank angle). The Sperry autopilot is a gyroscopically controlled, hydraulically actuated system which automatically operates the flight control cable system to maintain a desired magnetic heading and a normal stabilized attitude.
Autopilot Control Valve Handle:
A manually operated autopilot control valve handle is mounted on the aft lower face of the control pedestal and has ON and OFF positions.
Autopilot Emergency Shutoff Valve Handle:
A manually operated autopilot emergency shutoff valve handle is mounted on the hydraulic control panel and has ON and OFF positions. When the handle is in the OFF position, a shutoff valve installed in the hydraulic fluid pressure line is mechanically closed to divert the flow of oil from the autopilot system in case of damage to the oil lines resulting in fluid loss. The ON position is intended for normal autopilot operation.
Elevator Control Knob:
The elevator control knob is located on the autopilot control panel. It controls the aircraft in the pitch attitude. Rotating the knob will result with a nose-up or nose-down attitude.
Aileron Control Knob:
The aileron control knob controls the aircraft about the roll axis. Turning the knob will set a roll attitude, or will bring the aircraft to a level attitude.
Rudder Control Knob:
The rudder control knob controls the aircraft about the vertical axis. In the real-world Sperry autopilot, this knob was used to produce right of left hand turn.
In the VSKYLABS C-47, the Rudder Control Knob has two functions:
- To serve as a heading selection (heading bug) for the included S-TEC modern autopilot system.
- DG Sync is done manually using the sync-knob.
- Trim the aircraft to fly "hands off".
- Autopilot control valve handle - ON.
- Trim the aircraft is the axis indicated by the gyro indexes with the autopilot in operation.
- To turn off the autopilot, place the autopilot control valve handle in the OFF position.
- Corrections for pitch and bank (thus heading) are made with the 'elv', 'ail' knobs.
- Heading bug ("Rudder knob") mode is not available in the VSKYLABS C-47 Sperry Autopilot mode.
- In the above workflow, it is quite easy to fly with the autopilot being engaged, even in a rapid navigation route. The aircraft is responding nicely and unless you tried to engage the autopilot while flight situation wasn't stable, it is very comfortable. Every once in a while a minor heading correction (using the aileron knob) is needed.
- During prolonged flight or excessive flying attitudes (in pitch and bank), the gyro may drift and will not be aligned to the magnetic north. In such a case, you will notice a difference between the gyro-based heading indication and the magnetic compass heading indication, which can grow to be significant. In such a case, pushing the Rudder knob (clicking on it) will re-align the gyro to the magnetic north.
