The Morane-Saulnier MS.406 was a single engine, piston-powered, single-seat fighter appearing just before the outbreak of hostilities between France and Germany. Though a solid design by 1930's standards, the system did not fare well against the German Luftwaffe breed of fighters which featured better engines (and thus performance), armor protection and pilot training. Nevertheless, the M.S.406 played a critical role in the defense of France - despite the nations eventual capitulation - and is regarded as the best fighter design fielded by the country at the outbreak of the war.
Design-wise, the MS.406 was contemporary in nature and featured low monoplane wings, a three-bladed propeller and a retractable undercarriage. The 406 came along after changes were made to the existing M.S.405 model. The M.S.406 incorporated newer and lighter wings than her predecessor and also featured a retractable radiator under the fuselage. Power was derived from a single Hispano-Suiza 12Y-31 series V12 liquid-cooled engine developing up to 860 horsepower, providing some 301 miles per hour with a ceiling of nearly 31,000 feet and a range close to 500 miles. The engine was mounted in the front of the fuselage just forward of the cockpit. Vision from the canopy was adequate though it was situated aft of the wings. The canopy enclosure was divided into three sections and integrated into the base of the empennage. Armament could be considered quite subpar on the whole when compared to other aircraft of the time and centered around a 20mm Hispano-Suiza HS.404 series cannon firing through the propeller hub along with a pair of 7.5mm MAC 1934 series machine guns, one fitted to each wing.
Once inevitable combat began in 1938, the Morane-Saulnier MS.406 offered up hope in defense against Germany. By 1940 however, the system was wholly outclassed by the Luftwaffe Messerschmitt Bf 109 fighters and were not made in the quantity required to post up greater results. Many of the French production aircraft were unfortunately doomed to production delays as their airframes waited in warehouses without engines. In retrospect, the aircraft found more favor and success fighting on with other foreign operators of the system that included Finland and Switzerland. The Fins probably faired the best with the M.S.406 against the Soviets, though this was an M.S.406 flying in a modified form. By the Fall of France, surplus M.S.406's were put into service with the German Luftwaffe as trainer aircraft while others were sold off to allied nations.
In the end, the MS.406 was a serviceable fighter design with some factors to recommend it. On the other hand, when compared to its adversaries, the system found much more working against it in terms of performance, protection and firepower. In another time - perhaps some five years sooner - the system would have been something to be feared but the arrival of the Second World War onto French soil set the unprepared nation on a course of injustice to this aircraft. The M.S.406 appeared in just 1,176 total production examples - far below the numbers being fielded by the Luftwaffe and their Bf 109 series.