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Offered here is an original World War II Type K-4 Caliber .50 Automatic Computing Gunsight, acquired as part of a group of aircraft components from an individual who was personally involved in the restoration/refurbishment of B-17F Flying Fortress serial number 42-3374 at Offutt Air Force Base, Nebraska. That aircraft is the genuine WWII B-17F now preserved and displayed as “Homesick Angel.”
THE K-4 AUTOMATIC COMPUTING GUNSIGHT
The K-4 was far more than a conventional optical gunsight. It was a sophisticated WWII electromechanical/analog fire-control computer developed for use with the Sperry lower ball turret. U.S. Army Air Forces technical documentation identifies the K-4 as the lower-turret version of the Caliber .50 Automatic Computing Sight system. Closely related to the K-3 used in upper turret installations, the K-4 was configured for the operating position and mechanical connections required by the lower ball turret.
The sight incorporated an optical tracking system, range-finding equipment, ballistic cams, gears, shafts and variable-speed prediction mechanisms. While the gunner tracked an attacking aircraft, the K-4 mechanically calculated the necessary target lead, ballistic deflection and firing correction required to bring the trajectory of the turret\'s twin .50-caliber machine guns onto the moving target. The sight therefore functioned as a genuine mechanical analog computer, continuously solving a changing three-dimensional aerial-gunnery problem while the bomber, turret and attacking aircraft were all moving. This made the K-4 one of the most technically advanced pieces of equipment inside the Sperry ball turret and an outstanding example of WWII-era fire-control technology.
B-17F 42-3374 – THE SURVIVING “HOMESICK ANGEL”
The aircraft associated with this sight\'s restoration provenance is B-17F-50-DL Flying Fortress serial number 42-3374, Douglas construction number 8310. The aircraft was built by Douglas Aircraft at Long Beach, California, in 1943 and served entirely within the United States during World War II. Unlike many surviving B-17s associated with famous combat units, 42-3374 never deployed overseas and never flew combat missions.
Following the war, the aircraft was transferred to Metro-Goldwyn-Mayer Studios in Culver City, California, where it was intended for motion-picture use. The proposed production was never completed, and the aircraft remained with MGM for many years, eventually surviving in dismantled condition. Around 1970, 42-3374 passed to Ed Maloney\'s Planes of Fame collection at Chino, California, where it continued to survive, largely dismantled.
In 1981, the aircraft was transferred to Beale Air Force Base, California, where preservation and reconstruction work was performed during the 1980s. In May 1989, B-17F 42-3374 was transferred from Beale AFB to Offutt Air Force Base, Nebraska.
It was at Offutt AFB that the aircraft underwent the restoration and assembly work directly relevant to the provenance of this K-4 gunsight and the accompanying group of components. At Offutt, the aircraft was restored for permanent static display and ultimately painted and marked to represent the original wartime “Homesick Angel.”
THE ORIGINAL HOMESICK ANGEL
An important distinction should be made between the surviving aircraft and the original combat aircraft whose identity it represents. The original wartime Homesick Angel was B-17F serial number 42-30230, assigned to the 388th Bombardment Group, 562nd Bomb Squadron and operated from England during 1943.That aircraft flew combat missions in Europe and was eventually written off following a forced landing.
The aircraft surviving today is 42-3374, not 42-30230. B-17F 42-3374 did not fly combat, but it is itself a genuine WWII-manufactured Flying Fortress. At Offutt it was restored and given the markings and identity of the original 42-30230 “Homesick Angel” as a memorial representation of the wartime aircraft and the crews who flew B-17s in combat.
The surviving aircraft\'s preservation history can therefore be summarized as:
Douglas Aircraft, Long Beach – 1943
U.S. Army Air Forces stateside service
MGM Studios, Culver City
Planes of Fame, Chino
Beale Air Force Base
Offutt Air Force Base – 1989
Restored and displayed as “Homesick Angel”
PROVENANCE OF THIS K-4
This gunsight was acquired from the collection of an individual who was personally involved in the restoration/refurbishment of B-17F 42-3374 at Offutt Air Force Base. The K-4 was not acquired as a single unrelated surplus artifact. It was obtained together with a group of additional aircraft components retained or acquired by the same individual during the Offutt restoration of the B-17.
That group provenance is an important part of the history of this piece.
The sight and associated items remained together in the collection of an individual who had firsthand involvement with the aircraft during its restoration at Offutt, providing a meaningful restoration-era connection to the genuine surviving B-17F 42-3374.
The historically accurate attribution is therefore: An original WWII K-4 automatic computing gunsight acquired as part of a group of B-17 components from an individual involved in the Offutt AFB restoration of B-17F 42-3374, the genuine WWII Flying Fortress restored and displayed as “Homesick Angel.”
No claim is being made that this gunsight came from the original combat Homesick Angel, serial number 42-30230, or that it flew combat during World War II.
Instead, its significance lies in its identity as an original WWII K-4 ball-turret computing gunsight and its documented collection history connecting it with the Offutt restoration of surviving B-17F 42-3374. The sight has not been electrically or mechanically tested and is offered as a historic aviation artifact, collectible and display/restoration piece. Please examine all photographs carefully for exact markings, configuration, completeness and condition. Taken together, the K-4 and its provenance represent several important chapters of aviation history: WWII B-17 production, Sperry ball-turret aerial gunnery, mechanical analog fire-control computing, MGM\'s postwar preservation of 42-3374, and the aircraft\'s eventual restoration at Offutt AFB as “Homesick Angel.”
For the serious WWII aviation, B-17 or aerial-gunnery collector, this is an unusually substantial surviving piece of original fire-control technology with a particularly strong connection to the restoration history of a genuine surviving B-17F Flying Fortress.This version now makes Offutt AFB the provenance point throughout and treats Beale only as an earlier stop in the aircraft’s preservation history.
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