Description
WWII B-29 Upper Ring Sight Azimuth Gearing Assembly, GE P/N 8007577G2, Less Selsyns
The WWII B-29 Upper Ring Sight Azimuth Gearing Assembly, GE P/N 8007577G2, Less Selsyns was manufactured by General Electric for the Model 2CSR3A1 Upper Ring Sighting Station used on the Boeing B-29 Superfortress. Its package label identifies it as Gearing Assembly, Az. (Less Selsyns) and carries a May 1945 package date.
This is the sight-side azimuth gearing that provided mechanical input to two Selsyn transmitters. It is not a turret-drive gearbox or the complete sighting station. The two electrical Selsyn transmitters are not included.
Historical Significance
The B-29 was the first production aircraft to use analog computers to remotely aim and fire aircraft gun turrets. Its General Electric central fire-control system allowed gunners to aim from sighting stations inside the aircraft while electrically controlled turrets followed their lines of sight.
The upper gunner operated from a raised sighting position and could direct the forward and rear upper turrets. The WWII B-29 Upper Ring Sight Azimuth Gearing Assembly, GE P/N 8007577G2, Less Selsyns was part of the position-transmitting mechanism inside that upper sighting station.
The B-29 Central Fire-Control System
The B-29 system linked each gunner’s sight to remotely mounted turrets through Selsyn position signals, servo equipment, and analog fire-control computers. The larger system corrected for factors such as lead, ballistics, and parallax. This gearing assembly had the narrower role of translating the upper ring sight’s azimuth movement into mechanical drive for the sight’s Selsyn transmitters.
What This Item Is and Does
The assembly mounted on the rotating inner ring of the 2CSR3A1 Upper Ring Sighting Station. As the gunner moved the sight left or right, its drive gear engaged the station’s fixed ring gear and operated two azimuth Selsyn transmitters.
The gearing supported a one-speed Selsyn for coarse position and a 31-speed Selsyn for precise position. Those transmitters converted sight movement into electrical azimuth information used by the central fire-control system so the selected remote turret or turrets could follow the gunner’s aim.
Key Features
- Official nomenclature: Gearing Assembly, Azimuth
- General Electric part number: 8007577G2
- End item: Model 2CSR3A1 Upper Ring Sighting Station
- Aircraft application: Boeing B-29 Superfortress
- Manufacturer identified on the package label: General Electric Co.
- One-speed and 31-speed azimuth gearing for coarse and precise Selsyn position signals
- Package date: May 1945
- Package exclusion: Less Selsyns; the two Selsyn transmitters are not included
Why This Item Matters
This assembly is a documented part of the B-29’s advanced remote fire-control equipment. It shows how the gunner’s physical sight movement was coupled to electrical position transmitters before that information entered the wider turret-control system.
Its marked part number and matching package label make it useful as a display component, restoration reference, or research example for studying General Electric’s wartime aircraft fire-control engineering.
About This Item
The assembly bears the 8007577G2 marking. Its package label reads AAF Stock Classification 11-E, Gearing Assembly Az. (Less Selsyns), For—Ring Sight 2CSR3A1, On—B29 Plane, and General Electric Co. The label is dated May 1945, which is a package date rather than a stated manufacture date.
The assembly has a black-painted housing with an exposed drive gear, mounting points, and enclosed gearing sections. The two electrical Selsyn transmitters named by the system description are excluded, as stated by the package label.
Ideal For
This documented B-29 fire-control component is well suited for:
- Boeing B-29 Superfortress and WWII aviation collections
- Museum exhibits on remote aircraft armament and fire control
- B-29 sighting-station restoration reference
- Research into General Electric analog and electromechanical systems
- Aviation education, technical displays, and interpretive exhibits
- Film and prop departments seeking an identified period aircraft component
Approx length 9", Approx width 6", Approx height 4", Approx weight 4lbs.
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