Morane-Saulnier M.S.406

The Morane-Saulnier M.S.406 was France’s most numerous pre-war/early-war single-seat fighter and the evolution of the earlier M.S.405 prototype. Designed to meet a 1934 French “C1” requirement for a modern single-seat interceptor, the M.S.405 (first flown 8 August 1935) was developed into the production M.S.406 with a stronger airframe and the Hispano-Suiza 12Y engine; production examples began to enter service in 1938. The type was modern for a mid-1930s design — low-wing monoplane, enclosed cockpit and retractable undercarriage — but by 1939–40 it was already outclassed in speed and climb by the latest Messerschmitt Bf 109 variants and other contemporary fighters.

Development and production

Morane-Saulnier’s design work (led by Paul-René Gauthier) produced the M.S.405 prototype which evolved into the M.S.406. Early flight trials showed generally good handling but also revealed areas needing refinement (wing planform, propeller and cooling installations) before large-scale production.

France placed very large orders as rearmament accelerated; nationalised factories were also used because Morane-Saulnier alone could not meet demand. Total production of M.S.405/406 family airframes is commonly cited at roughly 1,100–1,200 examples (often quoted as about 1,176 built). The MS.406 was one of only two French designs to pass the 1,000-aircraft mark before/during WWII.

Operators

Croatia

Croatian forces of the Independent State of Croatia (armed and equipped in the patchwork aftermath of 1941) operated some captured or transferred MS.406s; between 38 and 45 were delivered in 1943. They were used for local defence and ground-attack/air policing tasks.

Moraine Saulnier 406 NDH Air Force with two Fiat G.50 fighters in the background

Finland

Finland received its first MS.406s in February 1940 (roughly 30 delivered during the Winter War period, and later additional examples and M.S.410/M.S.411 types via other channels). Finnish aircrews used the type in both the Winter War and Continuation War; the type was valued for manoeuvrability at low altitudes but was increasingly obsolete versus newer Soviet types.

Desperate for performance improvements, Finnish engineer Aarne Lakomaa led a local upgrade programme to re-engine the Morane with more powerful powerplants and improve aerodynamics. The most famous conversion — the Mörkö-Morane (“Mörkö” = bogeyman) — used captured and/or German-supplied Klimov M-105P (a development of the Hispano-Suiza 12Y family, usually rated ~1,100 hp) together with a new cowling, improved oil cooler (often taken from Bf 109 components), aerodynamic refinements and strengthened fittings. Armament on conversions was also upgraded (some received 20 mm MG 151/20 cannon or other heavier guns).

The prototype Mörkö-Morane (MS-631) first flew in January 1943 and showed significantly increased speed and ceiling compared with stock MS.406s; although conversion programme pace was limited by parts and wartime conditions, the Mörkö conversions that reached front-line units proved successful locally — one Finnish pilot (Lt. Lars Hattinen) scored several victories in the type. The programme was never completed to convert all Finnish airframes before the changing strategic situation halted mass conversion; by war’s end only a modest number had been converted and the survivors later served as trainers.

France

The M.S.406 formed a large part of the Groupes de Chasse in the Armée de l’Air in 1939–40. During the “Phoney War” it was one of the few French fighters capable of ~400 km/h, but when Germany launched the Blitzkrieg in May 1940 the M.S.406’s relative lack of speed, limited firepower (one fuselage 20 mm cannon + two wing machine guns in early fits) and poor high-altitude performance meant it suffered heavy losses against Bf 109E and Bf 110 formations. It performed respectably at lower altitudes and some French pilots scored successes, but attrition and operational factors quickly reduced its effectiveness.

Morane Saulnier M.S.406 No. 846 of 1st Esquadrille of GC III/1 at Rozay-en-Brie 8 June 1940

Free France

The Free French Flight (the most direct precursor of the Free French Air Force) was composed of three flights, with the No.2 being the one equipped with fighters. Hierarchically it was dependant of the 33 Squadron RAF and, when it was formed in July 1940 in the Middle East, it was equipped with Ms.406. They were soon replaced by Hurricanes.

Vichy France

Following the June 1940 Armistice, the status of the Morane-Saulnier M.S.406, the primary French fighter at the outbreak of the conflict, shifted drastically. While considered marginally effective against the Messerschmitt Bf 109E during the Battle of France, the Armée de l’Air de Vichy inherited several hundred airframes, designated for service within the remaining overseas territories under the limitations imposed by the German and Italian Armistice Commissions. These units, primarily were centred in North Africa, the Levant, and Indochina. The M.S.406 was thus elevated from a largely obsolete defense interceptor to the principal frontline fighter for Vichy France.

Morane-Saulnier 406 of the Vichy French Air Force

Germany

Following the collapse of France in June 1940, large numbers of French aircraft fell into German hands, among them several hundred Morane-Saulnier M.S.406 fighters. Though obsolete by 1940 standards, the M.S.406 represented a substantial asset to the Luftwaffe and the German occupation authorities, both as a source of spare parts and as a training and liaison platform. The type went on to serve under German control in multiple capacities, including Luftwaffe auxiliary use, collaborationist and satellite air forces, and even in conversion programs that produced new aircraft types for Axis allies.

Morane Saulnier M.S.406 in Luftwaffe Markings

Italy

The Morane-Saulnier M.S.406, France’s principal fighter at the outbreak of World War II, saw limited but intriguing postwar service in several countries, including Italy. Its use by the Regia Aeronautica (Royal Italian Air Force) was not the result of purchase or alliance, but rather of circumstance. After France’s armistice with Germany in June 1940, several examples of the M.S.406 and its derivative, the M.S.410, fell into Italian hands. These aircraft were subsequently evaluated, briefly operated, and later used for training and technical experimentation, providing Italy with valuable insight into contemporary French aviation design.

Morane-Saulnier M.S.406 In Italian Service

Poland

When Germany invaded Poland in September 1939, many experienced Polish airmen escaped through Romania to France, determined to continue the fight against the Axis powers. These men formed the nucleus of the Polish Air Force in exile, which came under French command in 1939–1940. Among the aircraft types they flew in combat during the Battle of France, was the Morane-Saulnier M.S.406, France’s principal fighter at the outbreak of World War II.

French Morane Saulnier MS 406C1 with Polish Airforce in France 1940

Switzerland

Switzerland purchased pattern MS.406s and then built the type under licence as the D-3800 (sometimes referred to as MS.406H in contemporaneous sources). The Swiss-built D-3800s used Swiss instruments and locally produced components (Saurer-built engines/props in early runs) and replaced the French drum-fed MAC wing guns with Swiss belt-fed guns, which eliminated the pronounced wing-bulges on French machines and solved jamming/freezing problems the French had experienced. Early D-3800s also had Swiss-standard radio and instruments.

After initial D-3800 production, Dornier-Altenrhein and Swiss industry continued development: the D-3801 incorporated a more powerful locally-licenced Hispano-Suiza (HS-51 / 12Y type improvements ~1,060 hp in Swiss fit), revised engine installation, revised exhausts and improved cooling — changes intended to raise top speed and reliability (these paralleled some late French MS.411/MS.412 work). Swiss D-3801s also retained the belt-fed wing guns and other Swiss fittings. Over the war years surviving D-3800 airframes were progressively modified to later D-3801 standard (cooling, hydraulics, ejector exhausts), leaving Swiss examples better suited to neutral air-defence duties than their original French counterparts.

The Swiss changes improved reliability (esp. gun/cold-weather performance) and gave Swiss Moranes a longer useful life on neutrality patrols. They never matched late-war fighters in absolute performance, but the Swiss conversions were an effective stopgap for Swiss defence needs.

Doflug D.3802

Turkey

Turkey purchased some MS.406s in the late 1930s as part of its pre-war modernisation; these were mainly used for air force strengthening and training rather than combat in WWII.