Formation Stick and Armrest for Type C-1 Automatic Pilot System
This is a WWII-era Formation Stick and Armrest, an accessory to the Type C-1 Automatic Pilot System used in US Army Air Force bombers such as the B-17 Flying Fortress and the B-24 Liberator (see illustration from the B-17G Flight Manual dated 1944).
The formation stick was used to quickly maneuver the aircraft with minimum physical effort while the C-1 Autopilot was on and the aircraft was assuming, or in, formation flight. Two formation sticks were installed on pedestals, each with an armrest, one to the left of the pilot's seat, and the other the right of the co-pilot's seat.
The formation stick consists of a handle and the control mechanism. The handle has a grip, a microphone trigger switch, and a transfer button on the top. The microphone trigger switch engaged the communication system. The transfer button, when pressed momentarily, will transfer control to that stick. The handle, which moves forward or back when pressure is applied, is mounted on a stalk, which moves left or right when pressure is applied. These movements signal to the C-1 automatic pilot to maneuver the aircraft accordingly.
The control mechanism, which is the square box to which the stalk is attached, contains an elevator potentiometer and a gear train which were the interface between the commands given by the action of the stick and the downstream C-1 system.
This example has the adjustable armrest and an adjustable swivel mount to affix to a pedestal stand (not included) which would be secured to the flight deck.
This formation stick is experienced but in terrific shape for its age. The microphone trigger switch and the transfer button both operate. The handle and stalk both move smoothly. The control mechanism box is ~4 inches square and the handle rises ~10 inches from its axis on the box. The entire assembly stands ~18 inches high and ~14 inches front to back.