Morane-Saulnier M.S.406

The M.S.406 was a French Armée de l'Air fighter aircraft built by Morane-Saulnier starting in 1938. Numerically, it was France's most important fighter during the opening stages of World War II.

Although sturdy and highly manoeuverable, it was under-powered and weakly armed when compared to its contemporaries. Most critically, it was out-performed by the Messerschmitt Bf 109E during the Battle of France. The M.S.406 held its own in the early stages of the war (the so-called Phoney War), but when the war restarted in earnest in 1940, losses to all causes amounted to approximately 400 aircraft. Out of this total some 150 were lost to enemy fighters and ground fire, another 100 were destroyed on the ground in enemy air raids and the remainder was deliberately destroyed by French military personnel to prevent the fighters from falling into enemy hands intact. In return M.S.406 squadrons achieved 191 confirmed victories and another 83 probable victories. The type was more successful in the hands of Finnish and Swiss air forces who developed indigenous models.

M.S.405
In 1934, the Service Technique Aéronautique (Aeronautical Technical Service) of the Armée de l'Air issued the "C1 design" requirement for a new and completely modern single-seat fighter with a monoplane layout and retracting landing gear.

Morane-Saulnier's response was the M.S.405 developed by Engineer in Chief Paul-René Gauthier. The MS.405 was a low-wing monoplane of mixed construction, with fabric-covered wooden tail, but a bonded metal/wood material (Plymax) skin fixed to duralumin tubing. Plymax consisted of a thin sheet of duralumin bonded to a thicker sheet of plywood. Morane-Saulnier had a long history of producing warplanes dating back to pre-World War I years, but in the inter-war period, they had concentrated on civil designs. The aircraft was a departure for them, being their first low-wing monoplane, first with an enclosed cockpit, and first design with retracting landing gear. Prior to this, their most modern designs were fixed-gear parasol monoplanes.

The new 860 hp Hispano-Suiza 12Ygrs engine driving a two-pitch Chauvière propeller powered the first M.S405-1 prototype, which flew on 8 August 1935. Development was very slow, and the second M.S.405-2 prototype with a 900 hp Hispano-Suiza 12Ycrs engine didn't fly until 20 January 1937, almost a year and a half later. With the new engine the fighter reached 275 mph, fast enough to secure an order for a further 16 pre-production prototypes, each including improvements on the previous version.

M.S.406
The result of these changes was the M.S.406. The two main changes were the inclusion of a new wing structure which saved weight, and a retractable radiator under the fuselage. Powered by the production 860 hp HS 12Y-31 engine, the new design was over 5 mph faster than the 405, at 304 mph. Armament consisted of a 20 mm Hispano-Suiza HS.9 or 404 cannon with 60 rounds in the V of the engine and fired through the propeller hub, and two 7.5 mm MAC 1934 machine guns (one in each wing, each with 300 rounds). A weakness of the MAC 1934 was its operation at high altitudes. It was found that at altitudes over 20,000 ft, the guns had a tendency to freeze. Heaters were added to the guns for high altitude use.

M.S.410
While the 406s were entering service in 1939, an upgrade series was started to improve the design. The result was the M.S.410, which included a stronger wing, simpler fixed radiator in place of the earlier retractable design, four belt-fed MAC guns in place of the earlier two drum-fed weapons, and exhaust ejectors for additional thrust. The added thrust boosted the top speed to 316 mph, an improvement of about 10 mph over the 406.

Production had just started when France fell, and only five examples had been completed. Production was allowed to continue under German supervision, converting earlier 406s to the 410 standard, but many of these received only the new wings.

M.S.411, M.S.412
A single example of the M.S.411 was constructed by converting the 12th aircraft of the pre-production line with the 406 wing and the 1,000 hp Hispano-Suiza 12Y-45 engine. A later modification was started as the M.S.412 with the 1,050 hp Hispano-Suiza 12Y-51 engine, but this was not completed by the time the war ended.

M.S.450
In 1939, Hispano started prototype deliveries of the new Hispano-Suiza 12Z engine of 1,300 hp. One was fitted to a modified 410 to create the M.S.450, giving dramatic improvements in performance, especially at altitude. However the engine did not enter production before France fell, and the similarly modified Dewoitine D.520 (the D.523/D.551) was considered a better design for the engine anyway.

Other Variants
The M.S.406 airframe was also used in a number of other projects. The M.S.430 was a two-seat trainer built by inserting a "plug" in the central fuselage with an extra cockpit for the trainee pilot, and using the much less powerful 390 hp Salmson 9 radial engine. The M.S.435 was a more powerful version with the 550 hp Gnome-Rhône 9K engine.

D-3800
In 1938, Switzerland obtained a license for local production of the MS.406. Two MS.406H fighters were supplied to Switzerland in September 1938 and April 1939 to serve as pattern aircraft as the D-3800, retaining the earlier wing design of the 405, but powered by the newer Hispano-Suiza 12Y-31 engines as used by the MS.406.

Pre-production started with a run of eight aircraft from EKW with engines built by Adolph Saurer AG driving a new Escher-Wyss EW-V3 fully adjustable propeller. Instruments were replaced with Swiss versions and the drum-fed MAC machine guns with locally designed and built belt-fed guns, so eliminating the wing-bulges of the French version, and avoiding the freezing problems encountered by French guns. The first of these aircraft was completed in November 1939. The pre-production models were then followed with an order for a further 74 examples, which were all delivered by 29 August 1940. In 1942, a further two were assembled with spares originally set aside for the original production run.

During 1944, surviving aircraft were modified with new cooling and hydraulic installations, and were fitted with ejector exhausts. These modifications were the same standard as the D-3801 series, making them identical with the exception of the engine installation. At the end of the war the remaining aircraft were used as trainers, until the last one was scrapped in 1954.

D.3801/3803
The Swiss continued development of the MS.412 when French involvement stopped following the June 1940 Armistice. The Dornier-Altenrhein factory completed a prototype powered with a licenced-produced HS-51 12Y engine, generating 1,060 hp together with the fixed radiator and revised exhausts as tested on the MS.411, in October 1940. The new type retained the armament changes and other improvements introduced on the D.3800. This series was put into production in 1941 as the D-3801 with continued deliveries until 1945 with 207 completed. Another 17 were built from spares between 1947 and 1948. Reliability of the new engine was at first extremely poor, with problems with crankshaft bearings causing several accidents. The engine problems slowed deliveries, with only 16 aircraft produced in 1942 and a single aircraft delivered in 1943. The engine problems were eventually resolved in 1944. With 1,060 hp from the Hispano-Suiza 12Y-51, the speed was boosted to 332 mph, roughly equivalent to the D.520 or the Hurricane. Weights were between 2124 - 2725 kg. After being retired from operational use as a fighter when the North American P-51 Mustang was acquired in 1948, the type remained in service as a trainer and target tug until 1959.

The D.3802 was based on the MS.450, emerging as the MS.540, with a Saurer YS-2 1,250 hp engine. The prototype flew in the autumn of 1944, revealing several shortcomings, but it was capable of 630 km/h. 12 were produced seeing limited use with Fliegerstaffel 17 and some other units.

The last development of this aircraft was the D.3803, with 1,500 hp Saurer YS-3 engine, and modified dorsal fuselage (with an all-round visibility canopy). The D.3803 was armed with three HS-404 20 mm cannon (one in the nose, two in the wings), plus up to 200 kg bombs and rockets. Despite not having a powerful engine, the type reached 680 km/h at 7000 m. The performance was impressive, but the last development of this 1935 fighter design had several shortcomings and was not entirely successful. Its development was halted as P-51D Mustangs became available.

Mörkö-Morane
France sent 30 Morane-Saulnier to Finland, between 4 and 29 February 1940. By 1943 the Finns had received an additional 46 M.S.406s and 11 M.S.410s purchased from the Germans. By this point, the fighters were hopelessly outdated, but the Finns were so desperate for serviceable aircraft that they decided to start a modification program to bring all of their examples to a new standard. The aircraft designer Aarne Lakomaa turned the obsolete "M-S" into a first rate fighter, the Mörkö-Morane (Finnish for Bogey or Ogre Morane), sometimes referred to as the "LaGG-Morane". Powered by captured Klimov M-105P engines (a licensed version of the HS 12Y) of 1,100 hp with a fully adjustable propeller, the airframe required some local strengthening and also gained a new and more aerodynamic engine cowling. These changes boosted the speed to 326 mph. Other changes included a new oil cooler taken from the Bf 109, the use of four belt-fed guns like the M.S.410, and the excellent 20 mm MG 151/20 cannon in the engine mounting. However, supplies of the MG 151 were limited, and several received captured 12.7 mm Berezin UBS guns instead.

The first example of the modified fighter, MS-631, made its first flight on 25 January 1943, and the results were startling: the aircraft was 40 mph faster than the original French version, and the service ceiling was increased from 10000 - 12000 m.

Originally, it was planned to convert all the 41 remaining M.S.406s and M.S.410s with the Soviet engine, but it took time, and the first front-line aircraft of this type did not reach LeLv 28 until July/August 1944. By the end of the Continuation War in 1944, only three examples had been converted (including the original prototype). Lieutenant Lars Hattinen (an ace with six victories) scored three kills with the Mörkö-Morane, one with each Mörkö-Morane in the squadron. More fighters arrived from the factory, though, and the Mörkö-Moranes took part in the Lapland War as reconnaissance and ground attack aircraft. Not all the Mörkö-Morane conversions were completed before March 1945, when the entire re-engining programme was halted. After the end of the war, the total was brought to 41, which served as advanced trainers with TLeLv 14 until September 1948. In 1952 all remaining Finnish Moranes were scrapped.

Operational History
In the late 1930s, a war with Germany was clearly looming, and the Armée de l'Air placed an order for 1,000 airframes in March 1938. Morane-Saulnier was unable to produce anywhere near this number at their own factory, so a second line was set up at the nationalized factories of SNCAO at St. Nazaire converted to produce the type. Production began in late 1938, and the first production example flew on 29 January 1939. Deliveries were hampered more by the slow deliveries of the engines than by lack of airframes.

By April 1939, the production lines were delivering six aircraft a day, and when the war opened on 3 September 1939, production was at 11 a day with 535 in service. Production of the M.S.406 ended in March 1940, after the original order for 1,000 had been delivered to the Armée de l'Air, and a further 77 for foreign users (30 for Finland and 45 for Turkey). Additional orders for Lithuania and Poland were canceled with the outbreak of the war.

The MS 406 equipped 16 Groupes de Chasse and three Escadrilles in France and overseas, and 12 of the Groupes saw action against the Luftwaffe. The aircraft was very manoeuvrable and could withstand heavy battle damage, but was outclassed by the Bf 109 and losses were heavy (150 aircraft lost in action and 250-300 lost through other causes). After the armistice, only one Vichy unit, GC. 1/7, was equipped with the MS. 406.

Germany took possession of a large number of M.S.406s and the later M.S.410s. The Luftwaffe used a number for training, and sold off others. Finland purchased additional M.S.406s (as well as a few 406/410 hybrids) from the Germans, while others were passed off to Italy and some 48 to the Air Force of the Independent State of Croatia in 1943. Those still in French hands saw action in Syria against the RAF, and on Madagascar against the Fleet Air Arm. Both Switzerland and Turkey also operated the type; the Swiss actually managing to down a number of both German and Allied aircraft, 1944-1945.

Before the Pacific campaign proper, Vichy authorities in French Indochina were engaged in a frontier war against Thailand, during 1940-41. A number of M.S.406s stationed in Indochina downed Thai fighters before the French Air Force abandoned the theatre. Some examples of the M.S.406 were captured by the Thai Air Force.

In Finnish Service
The M.S.406 had a parallel career in Finland. In February 1940, the first 30 French fighters were allocated to LeLv 28, commanded by Major Jusu. These aircraft received the Finnish designations MS-301 to MS-330. They were used in combat during the Winter War, against the USSR and carried out 259 operational sorties and shot down 16 Soviet aircraft. In modified form, the M.S.406 were later involved in the Continuation War. Between November 1939 and 4 September 1944, Lv28 scored 118 aerial victories flying the Morane M.S.406 (the unit flew Bf 109Gs for a time, as well). The unit lost 15 aircraft. Total Finnish kills amounted to 121. The top Morane ace in all theatres was W/O Urho Lehtovaara, with 15 of his 44.5 total kills achieved in Moranes. The Finnish nicknames were Murjaani (blackmoor), a twist on its name, and Mätimaha (roe-belly) and Riippuvatsa (hanging belly) for its bulged ventral fuselage.

Operators

 * Nationalist Chinese Air Force ordered 12 aircraft in 1938 and they were shipped to Haiphong, but diverted to Escadrille EC 2, which fought against the Japanese and Thai in December 1940 One or two aircraft may have reached the Chinese Air Force
 * Independent State of Croatia
 * Zrakoplovstvo Nezavisne Države Hrvatske received 48 aircraft.
 * Ilmavoimat received 76 M.S.406 and 11 M.S.410
 * Armée de l'Air
 * French Navy
 * 🇫🇷 Vichy France
 * Vichy French Air Force
 * 🇩🇪 Germany
 * Luftwaffe operated captured aircraft.
 * 🇮🇹 Italy
 * Regia Aeronautica
 * Lithuanian Air Force ordered 13 Moranes, but none were delivered.
 * Polish Air Force ordered 160 aircraft, but none were delivered, due to the fall of Poland.
 * Polish Air Force in exile in France operated at least 91 aircraft in several training and combat units:
 * Groupe de Chasse de Varsovie
 * Section no.1 Łaszkiewicz GC III/2
 * Section no.2 Pentz GC II/6
 * Section no.3 Sulerzycki GC III/6
 * Section no.4 Bursztyn GC III/1
 * Section no.5 Brzeziński GC I/2
 * Section no.6 Goettel GC II/7
 * Jasionowski Koolhoven Flight
 * DAT section Krasnodębski GC I/55 based at Châteaudun and Étampes
 * DAT section Skiba GC I/55
 * DAT section Kuzian based at Nantes
 * DAT section Opulski based at Romorantin
 * DAT section Krasnodębski based at Toulouse-Francazal
 * Centre d'Instruction d'Aviation de Chasse at Montpellier
 * Ecole de Pilotage No 1 (Chasse) at Etampes
 * Ecole de Pilotage at Avord
 * Centre d'Instruction at Tours
 * Depot d'Instruction de l'Aviation Polonaise at Lyon-Bron
 * Montpellier Flight
 * Swiss Air Force
 * Turkish Air Force received 45 Moranes. At least 30 of them were originally intended for shipment to Poland and had Polish stencilling.
 * Royal Thai Air Force operated several captured aircraft.
 * Kingdom of Yugoslavia
 * Royal Yugoslav Air Force ordered 25 aircraft, but the fall of France precluded their delivery
 * Swiss Air Force
 * Turkish Air Force received 45 Moranes. At least 30 of them were originally intended for shipment to Poland and had Polish stencilling.
 * Royal Thai Air Force operated several captured aircraft.
 * Kingdom of Yugoslavia
 * Royal Yugoslav Air Force ordered 25 aircraft, but the fall of France precluded their delivery
 * Royal Thai Air Force operated several captured aircraft.
 * Kingdom of Yugoslavia
 * Royal Yugoslav Air Force ordered 25 aircraft, but the fall of France precluded their delivery