Liore-Olivier LeO 451

The LeO 45.01 B4 - designed by Jean Mercier to Armee de l'Air Programme A21 (1934) - first flew on 16 January 1937. It was an all-metal low-wing monoplane powered by two radial engines. The wings had considerable dihedral and the streamlined elliptical monocoque fuselage had a pointed and fully glazed nose. The landing gear was fully retractable. Accommodation provided for a pilot in an enclosed cockpit, behind which was the radio operator's panel and below the retractable ventral gun turret.

Production LeO 451s had two 849.5kW Gnome-Rhone 14N 48/49 or 38/39 radial engines in specially designed Mercier cowlings. Despite excellent performance, construction of the type was slow. Only five LeO 451s were on first-line strength by 3 September 1939. When France collapsed in June 1940 only 452 of some 1,700 ordered had been delivered. A number of modifications were incorporated during series production, the principal being a totally redesigned fin and rudder assembly. Armament included a fixed 7.5mm MAC 1934 nose machine-gun, another gun of the same type flexibly mounted in the ventral gondola, and a somewhat troublesome 20mm HS-404 on a special mounting in the dorsal position. Maximum bomb load - carried in fuselage and wing bomb bays - was 2,400kg.

The LeO 451s were used initially for long-range reconnaissance missions, then for daylight bombing during the Battle of France and in night raids on Italian targets during June 1940. A further 225 were ordered by the French Vichy regime, the type serving in French overseas territories, later relegated to transport and liaison duties (a number flown in these roles by the Luftwaffe). Twenty-seven LeO 451s were ceded to Italy in 1941 but saw little service.

There were numerous experimental conversions of the basic design. Several examples remained in use in secondary roles for several years following the end of the Second World War.