Morane-Saulnier MS.405 / MS.406 / Mörkö

Designed in response to a French Air Force C1 requirement initially issued in September 1934, the M.S.405 was of tubular metal construction, but other than the fabric-covered rear fuselage, it had Plymax - okoume plywood bonded to aluminium - stressed skinning. Powered by an 641-kW / 860hp Hispano-Suiza 12Ygrs engine, the M.S.405.01 first prototype flew on 8 August 1935, and the second, the M.S.405.02, with a 900hp HS 12Ycrs, on 20 January 1937.

A pre-series of 15 aircraft was ordered on 1 March 1937, the first flying on 3 February 1938 with an HS 12Ygrs engine and an armament of one 20mm and two 7.5mm guns. Various changes had been proposed meanwhile for the series model to which the designation M.S.406 was assigned, the new features being progressively introduced on successive M.S.405s (eg, the second featured an enlarged fuel tank, the fourth was fitted with the HS 12Y31 engine and the 12th had a simplified and lightened wing structure).

The HS 12Y31-engined 13th and 15th aircraft were delivered to Switzerland (as M.S.406Hs) in September 1938 and April 1939 as pattern aircraft for a licence-built version (D-3800). The 12th was subsequently re-engined with a 910hp HS 12Y45 and fitted with a fixed rather than semi-retractable radiator as the M.S.411 to provide a basis for the HS 12Y51-engined M.S.412 built in Switzerland as the D-3801. The final M.S.405 was flown on 21 June 1938 as a pattern aircraft for the series M.S.406. The MS.406 was also assembled by SNCAO at St Nazaire-Bouguenais.

The production version was the M.S.406 with a number of detail improvements, a lightened wing structure, and a more powerful engine: 1,077 of this variant were built. As a first-generation ‘modern’ fighter, the M.S.406 was obsolescent at the beginning of World War II, but was numerically the most important fighter deployed by the French Air Force. Deliveries commenced late in 1938, a production tempo of six daily being attained by April 1939, and 11 daily four months later. Possessing an armament of one engine-mounted 20mm cannon and two 7.5mm machine guns, the M.S.406 had an 860hp Hispano-Suiza 12Y31 engine with which it was markedly underpowered.

Production terminated in March 1940, at which time the Armee de l'Air had taken on charge 1,064 M.S.406s, of which 30 had been supplied to Finland during December 1939- January 1940, and 30 had gone to Turkey during February-March 1940. Subsequent purchases from the German authorities between late 1940 and late 1942 brought total procurement of the Morane-Saulnier fighter by Finland to 87 aircraft (including a number of M.S.410s). With the occupation of Vichy France in November 1942, German forces acquired a further 46 M.S.406s which (apart from two delivered to Finland) were supplied to the Croat Air Force. The Italians obtained 52 M.S.406s of which the 25 airworthy examples were delivered to the Regia Aeronautica.

The Finns later re-engined some of their aircraft with the 820-kW (1,100-hp) Klimov M-105P under the revised name Mörkö Moraani. The increasing obsolescence of the MS 406 led the Finnish Air Force to order, on 22 October 1942, the installation of a Klimov M-105P in an MS 406 airframe. The M-105P engine derived from the HS 12Y, afforded 1,100 hp for take-off, and a substantial quantity of this power plant, together with suitable VISh-61P propellers, had been captured by the Wehrmacht and was available to the Finns. A 20-mm MG 151 cannon was mounted between the cylinder banks, a Bf 109G oil cooler was adopted, an aerodynamically-improved engine cowling was introduced, and, with some local structural strengthening, the prototype conversion was flown on 4 February 1943 as the Mörkö (Ghost) or Mörkö-Moraani. Successful trials resulted in the decision to bring all surviving MS 406 and MS 410 fighters to Mörkö standard, but only two more were com-pleted before termination of the Finnish-Soviet conflict. Nevertheless, the conversion programme continued, and by 21 November 1945, the remaining Morane-Saulnier fighters had been modified, bringing the total number of Mörkös delivered into the Finnish inventory to 41 aircraft. These retained the two or (in the case of the MS 410 conversions) four wing-mounted 7,5-mm machine guns, but shortages of the MG 151 cannon necessitated this engine-mounted weapon being re-placed by a 12,7-mm Berezina UB machine gun in some aircraft. The Mörkö remained in service until 11 September 1948, when the survivors were placed in storage and scrapped four years later.

Gallery

MS.405
Engine: 1 x Hispano-Suiza HS 12Ycrs, 900hp
Max take-off weight: 2440 kg / 5379 lb
Wingspan: 10.62 m / 34 ft 10 in
Length: 8.17 m / 26 ft 10 in
Height: 2.71 m / 8 ft 11 in
Wing area: 17.10 sq.m / 184.06 sq ft
Max. speed: 443 km/h / 275 mph
Range: 1000 km / 621 miles

M.S.406
Engine: l x Hispano-Suiza 12Y-31, 641 kW (860 hp)
Span: 10.6m (34 ft 9.25 in)
Length: 8.15m (26ft 9in)
Height: 2.71 m / 8 ft 11 in
Wing area: 17.10 sq.m / 184.06 sq ft
Empty weight: 1893 kg / 4173 lb
Max T/O weight: 2470 kg. (5,445 lb)
Max speed: 302 mph / 486 km/h at 16,405 ft
Max range: 1000 km / 621 miles
Operational range: 497 miles
Ceiling: 9400 m / 30850 ft
Crew: 1
Armament: 1 x 20-mm Hispano-Suiza cannon and 2 x 7.5-mm (0.295-in) MAC mg

Mörkö
Engine: Klimov M-105P, 1,100 hp
Propeller: VISh-61P
Max take-off weight: 2 849 kg / 6,280 lb
Empty weight: 2106 kg / 4643 lb
Wingspan: 10.62 m / 34 ft 10 in
Length: 8.38 m / 27 ft 6 in
Height: 2.71 m / 8 ft 11 in
Wing area: 17.10 sq.m / 184.06 sq ft
Max. speed: 525 km/h / 326 mph at 13,125 ft (4 000 m)
Initial climb, 4,921 ft/mm (25 m/sec)

Morane-Saulnier M.S.406