The origins of the SE.100 predate the creation of the
SNCASE (Sud-Est) company in the
nationalisations of 1937. It was designed by Pierre Mercier and
Jacques Lecarme at
Lioré et Olivier and was initially designated the LeO 50. Underpowered by two
Gnome-Rhône 14M engines, the design was recast to use the more powerful
Gnome-Rhône 14N-20 and
-21 engines, the same used in the
Lioré et Olivier LeO 451 bomber, and renamed the SE.100. The aircraft was of conventional all-metal construction, having a mid-wing layout. As with most French twin-engined aircraft of the era, the engines were handed, one airscrew rotating clockwise and the other anti-clockwise, to minimise torque. The aircraft had a twin tail. In production models it was planned to redesign the wing to use components from the
LeO 451 wing to ease production. The fuselage was short in appearance, with a long nose and a very short tail, the cockpit being connected to the gunner's position aft by a windowed corridor. The undercarriage was very unconventional, a taildragger with single main wheel at the front and one rear wheel fitted under each vertical tail and retracting into them, rather than two main wheels under the wings or engine nacelles and a single tail wheel as per usual practice. The aircraft was fitted with four
Hispano-Suiza HS.404 20 mm cannon in the nose and one in the gunner's post. The first prototype of the SE.100 flew on 29 March 1939 at Argenteuil, and a number of necessary changes were identified during the tests. It was destroyed in a crash on 5 April 1940. The aircraft proved to be around 100 km/h faster than the
Potez 631, the
French Air Force's current twin-engined fighter, and production was authorised. While the tests were proceeding, a second prototype was being built, incorporating the changes, the most obvious of which was the removal of the windowed corridor in the fuselage and its replacement by additional fuel tanks. The armament was increased to six cannon in the nose, two in the gunner's post and one additional cannon in the floor of the gunner's post. As the second prototype was being built, the
Citroën company was preparing to mass-produce the aircraft at their
Paris works, deliveries planned to begin late in 1940. At least two paper variants were studied, the
SE.101 powered by
Pratt & Whitney R-1830 Twin Wasp engines, and the
SE.102 powered by a different version of the Gnome-Rhône 14N. The
SE.500 and
SE.800 were to have been a 12-passenger transport and a four-engined transport, respectively, derived from the SE.100. ==Specifications (SE.100)==