The Morane-Saulnier D.3801 was an improved version of the M.S.406 produced in Switzerland after the fall of France.
Swiss interest in the M.S.406 family began in 1938 when they received two modified M.S.406Hs. The aircraft was then produced under licence in Switzerland as the D.3800. In the meantime work got underway on fitting a more powerful engine into the M.S.406. In France the twelfth pre-production M.S.405 was given a Hispano-Suiza 12Y45 engine, and was re-designated as the M.S.411. Work then began on the M.S.412, which would have been powered by the Hispano-Suiza 12Y51 engine. This aircraft was incomplete when the French armistice ended development in France.
Work on the new design continued in Switzerland and the D-3801 made its maiden flight in October 1940. It was powered by a 1,000hp Saurer-built 12Y51 engine and was armed with Swiss-built belt fed machine guns (as used in the D-3800). These guns meant that the D-3801 didn't have machine gun bulges in the wings, unlike the M.S.406, which was armed with drum fed guns.
The D-3801 was produced by three companies - the Eidgenössisches Flugzeugwerke (it is sometimes referred to as the E.F.W. D-3801), SWS and rather ironically Dornier-Werke AG. A total of 207 were built during the war. The first order, for 100 aircraft, was filled between December 1940 and June 1942. Ten more were completed from spare parts during 1943 and they were followed by 97 further new aircraft, built from September 1944. These aircraft were joined by seventeen aircraft produced from spare parts after the war.
The D-3801 was 23mph faster than the M.S.406 and had a better climb rate. It was used as a front line fighter during the war, and after being withdrawn from the front line continued to be used as a training aircraft and target tug. It was retired from Swiss service in 1959.
Engine: Hispano-Suiza 12Y51
Wingspan: 34ft 9 5/8in
Length: 26ft 9 1/3in
Height: 10ft 10 3/4in
Loaded Weight: 5,996lb
Top Speed: 332mph at 13,780ft
Initial climb rate: 3,287ft/ min
Range: 746 miles