Born from the XB-42 "Mixmaster" program - which sought a unique solution for a budget-conscious medium bomber platform alternative to the large and expensive Boeing B-29 "Superfortress" - the Douglas XB-43 "Jetmaster" was an evolved, jet-powered offshoot of the original design. The earlier XB-42 was powered by a pair of Allison inline engines arranged in a "pusher" setup at the rear of the aircraft which promoted speed gains over a traditional configuration. This left the forward / middle fuselage and wings clear of any mechanical obstructions and resulted in a more streamlined shape. At one point, the XB-42 was fitted with Westinghouse axial-flow turbojets which advanced it along altogether different lines. While neither design was adopted (two prototypes were completed), it did lay the foundation for the XB-43 which substituted the Westinghouse powerplants with a pair of General Electric J35 series engines. Two flyable XB-43 prototypes then emerged.
The XB-43 was more-or-less an add-on project to the in-development XB-42. The airframe proved feasible for the study of jet propulsion in a medium-sized bomber airframe so an agreement between the United States Army Air Force (USAAF) and Douglas Aircraft was had in March of 1944 with World War 2 (1939-1945) still ongoing. The aircraft resembled the XB-42 airframe on the whole while the inline engines were given up for the General Electric turbojets. Engineers added a pair of intakes along either side of the fuselage near the wingroots and exhaust ports took up the space where the propeller units once lay at the rear. The aircraft retained its single dorsal vertical tail fin (the ventral fin was deleted while the dorsal fin was enlarged), retractable tricycle undercarriage, and two-man cockpit arrangement. The nose section was glazed over for a bombardier's position bringing the operating crew total to three. Proposed defensive armament was 2 x 12.7mm heavy machine guns held in a remote-controlled tail turret though this was never fitted. The bomb load was to total 8,000 pounds. An attack variant (possibly designated as "A-43") was entertained that would have fitted multiple machine guns in the nose with the bombardier's position omitted and covered over. Additional weapons support in this version would have been added for underwing rockets.
Due to the limited availability of the GE J35 engines, the XB-43 product languished for several years before the aircraft could be flown. When fitted with its jets the aircraft suffered damage during ground running tests which saw one engine explode. A first flight was finally recorded on May 17th, 1946 but, by this time, World War 2 (1939-1945) had ended and many promising programs fell under the axe of the massive military drawdown that followed. The second prototype (given the developmental designation of "YB-43") followed in flyable form during 1947. The original J35 turbojets were then upgraded with J47 series engines.
The first prototype - s/n 44-61508 - was eventually cannibalized for its useful parts (to serve the second) and given up as a target. The second prototype - s/n 44-61509 managed a rather healthy test life until December of 1953. By this time, the now-USAF (the United States Army Air Force was renamed after World War 2) focused its energies on dedicated jet-powered bomber developments and not simply modified propeller-driven forms. This led to the cancellation of the XB-43 project in whole - the aircraft passed on for preservation to the National Museum of the United States Air Force (Dayton, Ohio).
As completed, the XB-43 exhibited a length of 15.7 meters, a wingspan of 21.7 meters, and a height of 7.4 meters. Its empty weight was 22,900 lb with a Maximum Take-Off Weight (MTOW) of 40,000 lb. Power was originally from 2 x General Electric J35-GE-3 turbojet engines of 4,000 lb thrust each. Maximum speed was recorded to be 507 miles per hour with a range out to 2,500 miles, and a service ceiling nearing 38,500 feet (requiring use of a pressurized crew cabin). Rate-of-climb reached 2,470 feet-per-minute.