The Bréguet Leviathan was a family of large all-metal biplane aircraft built in France in the early 1920s. The Bréguet XX and XXI were notable for being powered by Bréguet-Bugatti multiple engines, in two forms. The Bréguet XXI was powered by individual Bréguet-Bugatti U.16 engines initially and Lorraine-Dietrich 8b engines in tandem later. The Bréguet XXII had accommodation for about twenty passengers and was destroyed during a 1923 transport aircraft competition. Development of all three aircraft types was halted largely due to technical issues with power-plants and aircraft structure. Development and design Bréguet XX and Bréguet XXI In 1922 Bréguet Aviation flew both their all-metal Bréguet 19, a bomber/reconnaissance aircraft and the Bréguet XX. The latter was another all-metal biplane but much larger and powered by a Bréguet-Bugatti 32A Quadimoteur Type A, (two Bréguet-Bugatti U.24 engines mounted in tandem on a cradle, driving a single output shaft), with a single output shaft, for the first time on 20 June 1922. The engine assembly was placed in the forward fuselage and drove the nose-mounted single propeller via a shaft running through the forward engine half's cylinder banks from the combining gearbox between the two engine halves. A bomber variant, the Bréguet XXI, was also built with limited success; the partially built fuselage was displayed at the 1921 Paris Aero Salon, clearly showing the installation of the Bréguet-Bugatti 32A Quadimoteur Type A engine. The Bréguet XXI was later fitted with a Bréguet-Bugatti 32B Quadimoteur Type B, which grouped four 8-cylinder banks around a combining gearbox in an 'H' configuration. Bréguet XXII Unlike the very successful Bréguet 19, the Bréguet 20 and 21 proved unsatisfactory and were developed into the otherwise very similar Bréguet 22, which had a pair of Breguet-Bugatti U.16s mounted between the wings on either side. Since the double engines could continue to run with one half shut down; the Bréguet XX and XXI and XXII were sometimes referred to as four-engined aircraft (e.g.L'Aerophile). Moving the engines from the fuselage to the wings freed the fuselage for a passenger cabin which could hold 22, a large number in those days. The Type XX, Type XXI and Type XXII were all referred to as Bréguet Leviathan by contemporaries. The fuselages of the Type XX, Type XXI and Type XXII were similar flat-sided structures based on four cross-braced longerons, each of three parts. Since the nose of the XXII did not terminate