The SNCASE SE-400 was a prototype French twin-engined coastal patrol floatplane of the Second World War.
The aircraft's undercarriage consisted of two light alloy floats mounted beneath the engines.
[1] Flight testing showed that the SE-400 suffered from stability problems, and the aircraft had a new, larger, tail assembly fitted and its nose lengthened.
These modifications resolved the aircraft's handling problems,[3] but by this time the competing Breguet Nautilus had been ordered into production.
[4] The war situation and the continuing delays in the program resulted in the development of the SE-400 being abandoned on 24 May 1940, with the second prototype, a landplane powered by two 500 hp (370 kW) Lorraine 9N Algol engines,[a] left incomplete.