Latécoère 521

During the early 1930s, French aircraft manufacturer Groupe Latécoère set about designing a new large flying boat, which was intended to perform long-range flights, carrying both passengers and air mail. Around this era, France, Germany, the United Kingdom, the Soviet Union, and the United States, were endeavouring to launch ever-larger aircraft that would exceed the scale and payload capabilities of preceding aircraft and ultimately displace the ocean liner as the principal means of passenger travel. The development of such aircraft was a matter of national prestige and Latécoère quickly found support for their endeavour. The design, designated the Laté 520, was a large sesquiplane, comprising a central double-decked hull and a pair of stub wings, somewhat resembling the smaller Latécoère 300. It was named Lieutenant de vaisseau Paris, after an accomplished French naval officer and record-breaking pilot of the era. The Laté 520 featured a large double-decked hull that provided room for 80 passengers. A large number of stiffeners were present throughout the stub-wings to achieve a relatively stress-resistant construction, conveying and distributing stresses across the frames and hull spars. The wing of the Laté 520 comprised a centre section and two fabric-covered outer sections, these being braced to the stub wings. On the lower level, there was a salon occupied by 20 armchairs and tables, along with six deluxe double cabins, each with its own bathroom, and seating for a further 22 passengers, a kitchen, a bar, a lavatory, and a baggage hold. Originally, the Laté 521 was intended to be powered by an arrangement of four Hispano-Suiza 18Sbr W-18 engines, derived from an existing air racing engine; however, these engines would ultimately never become available. Controlling these engines posed several difficulties; thus the throttles for the six engines use an integral design involving declutchable tips and stirrups, which eased control difficulties and enhancing the aircraft's maneuverability on the water as well. ==Operational history==

On 10 January 1935, the first Laté 521 performed the type's first flight. Following a number of test flights, a highly-publicised demonstration flight was conducted in December 1935, flying via Dakar to Natal, Brazil, before turning north towards the French West Indies. This long distance flight was timed to deliberately coincide with the 300th year of French rule in the Americas. Shortly after successfully reaching Pensacola, Florida, the aircraft was caught in a hurricane and wrecked. The aircraft was salvaged and returned to France by ship, where it was rebuilt for regular service with flag carrier Air France on the trans-Atlantic routes. Prior to Air France's adoption of the Laté 521, the airline had only been able to carry air mail along some of its long distance routes, and thus had enabled new passenger services to be launched for the first time. During June 1937, the Laté 521 flew non-stop to Natal before returning to France via the North Atlantic. On 30 December 1937, the type established a new Fédération Aéronautique Internationale (FAI) record, carrying a payload of at an altitude of while flying over Biscarrosse, France. (The FAI Bulletin says it had six engines at the time.) Having been equipped with more powerful engines, the Laté 521 conducted a further four return flights to New York between May and July 1939. During one of these, pilot Henri Guillaumet flew from New York City to Biscarrosse at an average speed of , including with one engine out. On the outbreak of the Second World War, the Laté 521 was pressed into service with the French Navy, all aircraft were attached to the flotilla E.6, based in Port-Lyautey, Morocco, where they performed maritime patrol flights over the North Atlantic. After the Armistice of 22 June 1940 between France and Nazi Germany, the aircraft was flown to Berre, near Marseille. The Laté 521 remained at Berre intact up until August 1944 when, following the launch of Operation Dragoon by the Allies to liberate southern France, the aircraft was deliberately destroyed by the retreating German occupying forces. ==Variants==

Data from: ;520:The initial design of the 520 series, powered by 4 × Hispano-Suiza 18Sbr W-18 engines in tandem pairs. ;521 Lieutenant de Vaisseau Paris: The first completed aircraft, powered by 6 × Hispano-Suiza 12Ydrs. Operated by Air France on route proving flights the 521 was militarised in 1939 and operated by the Vichy government until stored at Marignane, finally being destroyed when Axis troops retreated from advancing Allies. ;522 Ville de Saint Pierre: The second aircraft of the 520 series, powered by 6 × Hispano-Suiza 12Y-37 engines, had a brief civilian career before being militarised similar to the 521. Operated by the Ministre des Colonies de Vichy, the 522 met a similar fate to the 521, being destroyed by retreating enemy troops in 1944. ;523: Three armed maritime patrol aircraft named '''''l'Algol, l'Aldébaran and l'Altair''''', operated by Vichy French forces. ;524: Projected variant of the 521 to have been powered by 8 × CLM Lille 6As opposed-piston 2-stroke diesel engines. ;525: Similar to the 524 but powered by 8 x Hispano-Suiza 12Y engines. ==Operators==

; • Air France • Aviation Navale ==Specifications (Laté 521)==