The emergence of the Boeing B-29 Superfortress marked a paradigm shift in aerial warfare. With its maiden production flight in July 1943, the Superfortress heralded a new era in America’s quest for a formidable, long-range strategic bomber. Conceived in 1938, its design aimed to surpass the range, payload, and speed limitations of its predecessors, primarily earmarked for deployment in the Pacific Theater of Operations. Boasting a remarkable loaded range of approximately 4,000 miles and a bomb load capacity of up to 20,000 pounds, the B-29 soared above its counterparts with a combat ceiling exceeding 36,000 feet and a top speed surpassing 350 miles per hour, cruising comfortably at 230 miles per hour. Its unparalleled capabilities rendered it peerless among bombers of its time.
Furthermore, the Superfortress wielded significant influence over American strategic maneuvers in the Pacific theater. As the United States already asserted control over the Solomon, Gilbert, and Marshall Islands, strategic planners opted to circumvent the Japanese stronghold in the Caroline Islands, redirecting their focus towards the Marianas Islands. This strategic pivot was partly spurred by the advent of the B-29, which could effortlessly bridge the 1,500-mile gap between the Marianas and the Japanese mainland, encompassing Saipan, Tinian, and Guam.
Innovations introduced by the B-29 extended beyond its operational capabilities, revolutionizing American air warfare technology. It pioneered a heated, pressurized crew cabin, enhancing crew comfort and combat efficiency while mitigating fatigue. The introduction of pressurization facilitated operations at unprecedented altitudes, often surpassing the reach of enemy interceptors. Additionally, the B-29 innovated with the implementation of dual-wheeled tricycle landing gear, a departure from the traditional tail or single nose wheel configurations, ensuring stability during landings. However, the pinnacle of its advancements lay in its state-of-the-art gunnery system, elevating it to the status of a veritable airborne fortress.
Central to its formidable defensive arsenal was the General Electric Company’s model 2CFR55B1 centralized fire-control system (CFC), revolutionizing bomber defensive capabilities. Comprising five gunsights, remotely operated turrets, targeting computers, and an electric gun-switching mechanism, the CFC seamlessly integrated defensive gunnery into a cohesive system. Each turret, remotely controlled from five distinct sighting stations dispersed throughout the aircraft, was synchronized with targeting computers, ensuring precise firing trajectories. Strategically positioned turrets encompassed both the forward and aft sections of the aircraft, fortified with meticulous engineering to safeguard against aerial threats from all angles.
The B-29 was manned by a crew of eleven, including five dedicated gunners. Positioned strategically throughout the aircraft, their roles varied from top gunner to tail gunner, each with specific responsibilities crucial to the aircraft’s defense.
At the pinnacle of the crew compartment, the fire control officer, colloquially known as the ring gunner, occupied a plexiglass blister atop the fuselage. Seated in a tall chair dubbed the “barber chair,” they oversaw the coordination of gunnery operations. Flanking the ring gunner were the blister gunners, stationed on either side of the fuselage, each peering through their respective blisters. Meanwhile, the bombardier, positioned in the aircraft’s nose, doubled as the nose gunner when not engaged in bombing duties.
The coordination of gunnery operations was intricate, with primary and secondary control assigned for each turret. Communication among the gunners via the interphone system was imperative, orchestrated by the fire control officer. The firing system was designed with safeguards to prevent accidental firing on the aircraft itself, relying on precise control switches and inter-gunner communication.
Equipped with Browning M2 .50-caliber machine guns, the turrets were essential for defensive maneuvers. To mitigate overheating, gunners were instructed to fire in short bursts, allowing for cooling intervals. Additionally, early models featured a 20mm cannon in the tail mount, adding firepower to the defensive arsenal.
Each gunner operated a manually controlled gunsight, featuring interchangeable sky filters and adjustable illumination for optimal targeting in various lighting conditions. The intricate setup ensured that the crew could effectively engage enemy threats, even in adverse circumstances.
Upon encountering a target, the gunner underwent a series of meticulous procedures. Initially, a visual identification of the enemy aircraft was imperative, followed by adjusting the target size knob on the gunsight, scaling from 35 to 150 feet to align with the wingspan of the target. As this adjustment occurred, the reticle size on the gunsight altered accordingly, displaying the current target size setting at the 12 o’clock position within the reticle circle. Aligning the reticle’s center dot with the target’s center, the gunner proceeded to fine-tune the gunsight’s range wheel until the target aircraft snugly filled the reticle circle.
Sustaining the pursuit demanded a seamless orchestration of the gunsight’s movement along both vertical (elevation) and horizontal (azimuth) axes to maintain the target within the reticle’s confines. Horizontal adjustments relied on the gunner’s bodily rotation along with the gunsight, while vertical movements were executed by rotating the hand wheel grips flanking the gunsight frame. Friction adjustments enabled the gunner to tailor the gunsight’s sensitivity to their liking.
Every maneuver of the gunsight, whether in elevation or azimuth, prompted a corresponding electrically activated adjustment in the guns or turret, facilitated by a system comprising differential selsyn generators, servo amplifiers, and amplidyne generators.
Except for the tail mount, the turrets boasted a full 360-degree azimuth rotation capability, while the guns could elevate to 90 degrees relative to the aircraft’s body. Rather than traditional triggers, firing was initiated by depressing buttons adjacent to the hand wheels, accessible to either thumb. Moreover, an action switch, triggered by the gunner’s left palm, functioned as a control override for the sighting station, ensuring operational continuity in the event of incapacitation.
During engagement, the gunner’s primary task was to accurately size, range, and track the target, firing at the optimal effective range. The Computerized Fire Control (CFC) system facilitated gun movement while continuously computing corrections necessary for precise targeting. Leveraging computer-calculated targeting extended the guns’ effective range to 900 yards, surpassing manual sighting by 50 percent and most enemy fighters’ guns by over twofold.
The computer introduced correction adjustments to account for variations from the mirrored movements between gunsight and guns, addressing factors like ballistics, parallax, and lead. Ballistics corrections compensated for projectile deflection due to gravity and wind, while parallax and lead corrections accommodated discrepancies in distance and target movement during flight.
To execute its correction computations, the computer relied on various inputs sourced from multiple channels. These included gun position, aircraft speed, altitude, outside temperature, target range, and relative velocity, meticulously fed into the system via electrical interfaces.
Distinct models of computers were deployed based on the level of parallax involved. Single-parallax computers managed stations with parallax between gunsight and one gun location, while double-parallax models were employed for stations controlling turrets with differing parallax levels.
Although the inputs were electrical, the computer’s calculations were executed mechanically due to technological limitations, necessitating a complex array of selsyns and potentiometers for conversion.
Comprising separate yet interconnected units within a bulky chassis, the computer encompassed ballistic, parallax computing, and lead calculating units. These units were finely tuned with parameters such as gun position, target range, aircraft speed, and ballistic characteristics, encapsulating the intricate process of precision targeting within the confines of its mechanical infrastructure.
The computer’s output, derived from the synchronized signals received from the gunsight selsyn and adjusted for the cumulative corrections, underwent conversion back into electrical impulses. These impulses then powered a servo amplifier, functioning as a feedback controller, which in turn operated the two gun-positioning motors—one for elevation and the other for azimuth. Consequently, the computer’s corrections were translated into adjustments in the guns’ and turret’s positions, deviating from the exact parallel alignment with the gunsight.
U.S. Army Air Forces archives document the production of 3,760 Superfortresses, primarily by Boeing, with approximately 70 percent manufactured in Wichita, Kansas, and Renton, Washington. The remaining aircraft were constructed in Marietta, Georgia, by the Bell Aircraft Company, and in Omaha, Nebraska, by the Glenn L. Martin Company, which later merged into Martin-Marietta.
Before deployment, meticulous alignment and testing procedures were undertaken for the weaponry and targeting systems. Initially, a bore sighting apparatus was employed to calibrate the guns within the turrets, followed by alignment procedures using designated sighting stations and predetermined targets located at least 100 feet away. Adjustments were carried out either at the sighting station or within the turret, depending on the specific gunsight and turret combination. Subsequent testing of the targeting computers and input mechanisms was conducted using sophisticated equipment.
The rapid production of the B-29s outpaced the implementation of the innovative Central Fire Control (CFC) systems, necessitating the training of USAAF crews for their operation. Corporal Robert W. “Bob” Truxell, initially deemed unfit for flight crew duty due to health concerns, completed B-29 CFC and computer training programs. His duties at the Bell Aircraft B-29 facility in Marietta included the clearance of civilians from completed B-29s for the alignment of gun turrets and central computers. Following the resolution of production bottlenecks, Truxell’s crew was deployed to various air bases for final adjustments before active service. Recounting his experiences, Truxell characterized his service as “reasonably secure and fulfilling.”
The innovative gunnery system of the B-29s presented a formidable challenge to Japanese fighter pilots. Between August 1944 and August 1945, B-29s engaged in over 31,000 combat sorties, during which they successfully downed 914 enemy aircraft while sustaining the loss of only 72 of their own, as documented in the Army Air Forces Statistical Digest of December 1945.
