Lockheed XB-30 (Model L-249) Four-Engined Heavy Bomber Aircraft Proposal
The Lockheed XB-30 Heavy Bomber proposal existed only as a design study heading into World War 2 - the aircraft based on the L-049 Constellation airframe.
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Before the Boeing B-29 "Superfortress" made its introduction in 1944 and forever changed the direction of the war in the Pacific, there were competing design submissions put forth by players in Consolidated, Douglas, and Lockheed. All were drawn up to fulfill a new U.S. Army heavy bomber requirement intended to provide the air service arm with a capable high-flying platform of considerable range. Consolidated delivered its B-32 "Dominator", which was introduced in January of 1945 and 118 examples were procured, while the Douglas XB-31 and Lockheed XB-30 managed only design studies before attention wholly settled on Boeing's entry.
Origins of the Lockheed XB-30 lay in the latter half of the 1930s when another World War in Europe (or a direct conflict with Japan in the Pacific) seemed a very likely possibility. This pressed Army authorities to pursue a new generation of bombers capable of excellent range while carrying a useful war load and flying higher than designs before it. Technological developments and political events in Europe influenced a committee arranged by General "Hap" Arnold and their recommendation was to pursue a new heavy-class aircraft. The arrival of World War 2 in September of 1939 added to the urgency and design studies were ordered by the Army.
The heavy bomber categorization dictated some of the inherent design of the aircraft during this period - a multi-person crew would be required to manage the onboard systems and stations, an aircraft of considerable dimension was needed to contain crew spaces, fuel tank, and bombs, and a four-engined configuration was required to ensure the bomber held the needed power and range to travel as far and as high as needed. The Army sought a bomber with a range of at least 5,000 miles.
Lockheed's entry was based on their L-049 "Constellation" ("Connie") transport (detailed elsewhere on this site) which was under development at the time. A first-flight of this aircraft occurred in January of 1943 and 88 were eventually built -fourteen inducted into the U.S. military (as the "C-69") and seventy-four constructed for commercial passenger service. This design origin meant that the Lockheed study - designated "XB-30" with the company model designator of "L-249" - carried the same general shape and configuration as the Model L-049. The bomber form therefore had the same tubular, somewhat deep fuselage, mid-set wing mainplanes, and triple-rudder tail unit. Each wing mainplane carried two engine nacelles. The flight deck was held forward in the design overlooking the nose and various crew positions were set about the fuselage, some arranged with defensive armament to protect the aircraft. It was estimated that the L-249 would require a crew of ten for optimal operation. A tricycle undercarriage gave the L-249 a most modern appearance - another quality carried over from the Constellation.