Modern-Aviation

The Bloch MB.150 (later MB.151 to MB.157) was a French low-wing monoplane fighter aircraft developed and produced by Société des Avions Marcel Bloch. It featured all-metal construction, complete with a retractable undercarriage and a fully enclosed cockpit.

The MB.150 was originally developed to conform with the requirements of the 1934 French Air Ministry competition seeking a new fighter design. Despite the competition being won by the competing Morane-Saulnier M.S.406, it was decided to proceed with development. Initially proving unable to attain flight, the modified prototype conducted its maiden flight in October 1937. Service trials of the MB.150 determined the aircraft to hold sufficient promise to warrant further work, leading to the adoption of an expanded and strengthened wing and a more refined Gnome-Rhone 14N-7 engine. During spring 1938, following the completion of further proving trials, an order for a pre-production batch of 25 aircraft was placed.

Redesigns of the MB.150 design led to the improved MB.151 and MB.152 which entered squadron service with the Armée de l'Air. By the outbreak of the Second World War, around 120 aircraft had been delivered to the Armée de l'Air, however most were not initially sufficiently equipped to be considered combat-capable. Additionally, an improved model, designated as the MB.155, which was capable of greater range; while ordered into production in 1940, only 10 aircraft had been completed by the Fall of France. Completed during the Vichy era, a further improved model of the aircraft, designated as the MB.157, featured a heavy and more powerful engine; while demonstrating promising performance, it did not enter production.

On 13 July 1934, the Service Technique Aéronautique (Aeronautical Technical Service) of the French Air Force issued the "C1 design" requirement for a new and completely modern single-seat interceptor fighter. Envisioned to make use of a monoplane layout and a retractable undercarriage, the prospective fighter aircraft was to serve as a replacement for the French Air Force's existing inventory of Dewoitine D.371, Dewoitine D.500, and Loire 46 aircraft. Amongst the various aviation companies who took interest in the specification, to which the potential for a large production order was attached, was French aircraft manufacturer Société des Avions Marcel Bloch.

The design team, headed by Maurice Roussel, was assembled at Bloch's Courbevoie facility in Paris. They designed an all-metal stressed skin monoplane, powered by a single 930 hp Gnome-Rhône 14Kfs radial engine and armed with a pair of wing-mounted Hispano-Suiza-built HS.404 cannon. During September 1935, construction of the type's first prototype, designated as the Bloch 150-01, commenced.

Although the C.1 competition was ultimately won by a rival design, the Morane-Saulnier M.S.406, it was decided to independently continue with the design's development. During 1936, these efforts culminated in the first attempted flight of the MB.150.01 prototype; unfortunately, the aircraft proved unable to leave the ground during the attempt. Disappointed, work on the design was temporarily halted, but development was resumed during early 1937. Following the implementation of various modifications, consisting of a strengthened wing of greater area, revised undercarriage arrangement and the installation of a 701 kW (940 hp) Gnome-Rhone 14N-0 radial engine with a three-blade constant speed propeller, on 29 September 1937, the MB.150 finally conducted its maiden flight.

Months later, the MB.150.01 was handed over to the Centre d'Essais du Materiel Aerien (CEMA) for service trials; during one such official test flight in December 1937, a maximum recorded speed of 434 km/h (269 mph) was attained. As a result of the CEMA flights, the prototype's performance proved to be sufficiently interesting as to warrant further development. This brought, at the beginning of 1938, a small increase in the aircraft's wing span, the replacement of the twin wing-mounted radiators by a single unit installed between the wheel wells, and the installation of an improved 14N-7 engine, which led to the prototype being re-designated as the MB.150.01M (M standing for modified). During spring 1938, further trials of the modified aircraft were performed by CEMA.

By this point, wider circumstances within France, such as the declining diplomatic situation between the European powers and the enactment of several urgent re-equipment programmes for the French Air Force, proved favourable for the MB.150. Specifically, on 15 March 1938, one such programme, referred to as Plan V, was adopted, calling for the near-unrealistic delivery of 940 modern fighter aircraft to the Air Force within the space of a year. Even the most optimistic projections saw 285 M.S.406 fighters delivered; while the MB.150 was deemed to have not yet completed development, it was decided to include the type within the production.

Accordingly, on 7 April 1938, upon the completion of trials in late spring 1938, the newly formed manufacturing consortium SNCASO received an initial order for a pre-production batch of 25 aircraft which, upon successful completion of the MB.150's development programme, was followed by the confirmation of a sizable order for 450 aircraft. Initially, 300 aircraft were to be delivered to the French Air Force by 1 April 1939; this was later cut down to 206 aircraft. In reality, only a single aircraft had been delivered by the prescribed deadline; other aircraft types also proved similarly unable to attain the tight delivery dates.