Douglas XB-42 and XB-43 bombers
Although best known for its role as a nuclear delivery vehicle over Hiroshima and Nagasaki, Boeing's B-29 Superfortress was a technological marvel in its own right when first flown, incorporating such advanced features as pressurization and remotely-controlled gun turrets. However, even with a world war raging, it was recognized that the Superfortress was a very expensive design to build and maintain, and some thought was given to procuring a less costly aircraft as a supplement. At the time, Douglas was designing a radical new attack type, the XA-42, that was potentially adaptable for use as a heavy bomber, and this was redesignated as the XB-42.
A very clean design with shoulder-mounted wings and side-by-side seating for the pilot and copilot, the XA-42 had a pusher configuration, using a pair of internally-mounted Allison V-1710 engines to turn contra-rotating propellers on the tail. A sizeable warload of 8,000lbs could be carried in the bomb bay; this was less than half the maximum capacity of the B-29, but the Mixmaster was also to be capable of flying at over 400 mph, and with lighter bombloads a range of 5,000 miles was projected.
The Mixmaster's fairly compact size and unusual configuration did not lend itself to the fitting of heavy defensive armament. but a few guns were worked into the design. Since no tail turret was possible, rearward protection took the form of two pairs of backward-facing .50-calibers fitted on the wings between the flaps and the ailerons. Initially, the XB-42 had separate "bug eve" canopies for the pilot and copilot, similar to those of the C-74 Globemaster and never-built XB-31 heavy bomber. The bombardier/navigator was given a clear plastic nose for bomb-aiming.
The first XB-42 flight took place on May 6, 1944. Despite problems with vibration, the Mixmaster's performance lived up to expectations, and indeed the design proved to be the fastest American bomber of the wear. One additional aircraft was built, flying in August 1944. This had a more conventional single canopy and more powerful -129 engines, but was lost in a crash several months later. Just prior to being lost, the second prototype completed a record-setting cross-country flight, averaging 433.6 mph between Long Beach, California and Boiling Field near Washington, D.C.
Despite its potential, the Mixmaster arrived as the end of the war was almost in sight, and since great numbers of more conventional aircraft were either on hand or on order, no operational B-42s were to be bought. Although deprived of the chance to see action, the Mixmaster did not immediately fade away postwar. The remaining prototype was put through a modification that saw it emerge in 1947 with V-1710-13 engines and a pair of Westinghouse 19-XB turbojets in underwing pods. It flew in this configuration for several more years, and was later donated to the National Air and Space Museum. The XB-42 design also lead directly to the XB-43 Jetmaster.
The first American pure jet bomber, the XB-43 was the result of an effort to get such a type into the air as quickly as possible, using the XB-42 Mixmaster as a basis. Development of the TG-180 (later J35) turbojet by General Electric was at an advanced stage, and the Mixmaster airframe was could easily accommodate a pair of these new powerplants. Thus, in March 1944 Douglas received a contract to develop and build the XB-43 prototype.
To further speed the process along, the XB-42 structural test airframe was to be finished to the new standard. The turbojets were to be housed internally, exhausting through tailpipes that took the place of the Mixmaster's propellers. Flush-mounted intakes were fitted to the sides of the forward fuselage, just below and aft of the "bug eye" canopies. The XB-42's vertical tail was also larger than that of its predecessor: this was necessary to compensate for the loss of directional stability caused by the deletion of the Mixmaster's ventral tail surface.
Although designated as a bomber, the type was also considered for use as a tactical interdiction machine, with a "solid" nose fitted with massed .50-caliber machine guns in the manner of the B-25 and A-26 gunships. Neither Jetmaster would ever be fitted with armament, production aircraft were to have been equipped with a tail turret with two .50-calibers, replacing the wing guns of the B-42.
Had the B-43 been available several years earlier, it may well have made its mark in service, as it had comparable performance to the Luftwaffe Ar-234 Blitz reconnaissance bombers that had proved so hard for Allied fighters to catch. However, by the time that the first prototype first flew in Mav 1946. North American's all-new XB-45 was nearing readiness, and this design looked likely to combine the Jetmaster's speed with a longer range and better load-carrying capability. This ended plans for an initial buy of fifty B-43As, but flight testing of the XB was to continue, and a second example was flying by 1948. Designated YB-43 and later nicknamed Versatile II, this aircraft served as a testbed for General Electric's J47, a successor to the J35. For this program., one of the proven J35s was retained for safety; adverse handling from the mismatched powerplants was minimized since both were as close as possible to the aircraft centerline.
In an era when prototype aircraft had short lifes, the YB-43 had a respectable career, flying until 1953. Versatile II was subsequently donated to the Smithsonian, where it remained in storage as of 2001, awaiting restoration.
A 1/72 scale vacuform kit of the XB-42 has been made by Wings Models; Anigrand has also made a 1/72 scale XB-42 and XB-43 in resin.
A large electric RC XB-42 project
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