The Bloch MB.150 was a family of modern, all-metal monoplane fighter types developed for the French Air Force prior to World War 2. The aircraft was developed to a 1934 French Air Force requirement for a new fighter/interceptor mount capable of speeds nearing 300 miles per hour and armed with machine guns and cannon. The endeavor pitted several French-based aviation firms against one another to showcase possible solutions. Among these was Societe des Avions Marcel Bloch (better known simply as "Bloch") with its single-seat, single engine monoplane MB.150. However, the government contract was given to competitor Morane-Saulnier whose streamlined MS 406 went on to see 1,176 examples produced with introduction into service occurring in 1938.
Undeterred, Bloch technicians continued supporting the MB.150 project to which a completed prototype, suffering from major issues, was unable to leave the ground on a proposed first flight in 1936. By 1937, engineers had installed a more powerful engine coupled with a new three-bladed propeller, revised wing elements and a new undercarriage which finally allowed the prototype to achieve the momentous event of a first flight during October. The French Air Force developed some interest in the Bloch project and intended to evaluate the type into 1938. The result of these tests produced a procurement order for 25 aircraft - though none would be based on the original prototype. Instead, the design focus had shifted on a pair of more capable prototypes in development - the MB.151 and the MB.152 fitted with Gnome-Rhone 14N-35 and 14N-25 engines respectively. The MB.152 entered French Air Force service as the MB.151.C1 with the MB.152 as the MB.152.C1. The aircraft proved comparable to the American Curtiss P.36 of the period.
The Bloch MB.152 proved the definitive production model with nearly 500 produced. This version was powered by a Gnome-Rhone 14N-25/-49 series air cooled radial piston engine outputting at 1,080/1,100 horsepower depending on fitting. This was coupled to a three-bladed variable fixed propeller assembly. The combination supplied the aircraft with a top speed of 316 miles per hour (280mph cruising) with a range of 370 miles and service ceiling of 32,800 feet.
MB.150 Series Armament Options
Standard armament for the MB.150 series varied somewhat as certain forms were finished with 4 x 7.5mm MAC 1934 M39 machine guns and others with 2 x 20mm Hispano-Suiza HS.404 cannons and 2 x 7.5mm MAC 1934 M39 machine guns. The latter form was undoubtedly the more potent variant.
As a whole, the MB.150 family of fighters were all-modern designs consisting of all-metal skin and understructure construction with low-set monoplane wing appendages. The wings were straight in their general design with rounded tips and set well-forward of amidships. The engine was fitted to the extreme forward section of the fuselage in a traditional manner, powering a three-bladed propeller installation. Interestingly, the cockpit was also situated well-forward in the design, shortening the visual obstacle that was the engine compartment to some extent. However, views were still obstructed by the short engine housing to the front, the wings to the lower sides and the raised fuselage spine aft of the cockpit. The canopy was completely enclosed as a two-piece assembly with the rear section sliding rearwards for access. The fuselage tapered at the rear to which a single vertical tail fin was affixed along with mid-mounted horizontal tailplanes. The undercarriage was retractable and of the "tail-dragger" arrangement consisting of two main single-wheeled landing gear legs and a diminutive tail wheel leg at the rear. As in similar tail-dragger aircraft designs, ground taxiing proved a challenge in itself with the pronounced "nose-up" appearance. Key qualities that made the MB.150 a "modern design" for the time were its retractable undercarriage, enclosed cockpit, use of metal skin construction and implementation of prominent monoplane wings.
The MB.150 was born out of the single MB.150.01 prototype which was powered by the Gnome-Rhone 14N-07 series radial piston engine. The MB.151 existed in its MB.151.01 prototype form which begat the MB.151.C1 production model and its Gnome-Rhone 14N-35 series engines. Some 144 examples of the type were completed. The MB.152 was born as the MB.152.01 prototype and was offered as the MB.152.C1 production form with its Gnome-Rhone 14N.25 engine of 1,050 horsepower. 482 examples of this type were delivered. The MB.155 proved the last definitive production form and was based on the MB.155.01 prototype which, in turn, was born from the MB.152. Power was supplied by a Gnome-Rhone 14N-49 series engine and 35 examples were produced.
Abandoned, Failed or Cancelled MB.150 Developments
The MB.153 was a one-off prototype fitted with the American Pratt & Whitney R.1830 Twin Wasp radial engine. The MB.154 was a proposed variant fitting the Wright R.1820 radial piston engine which fell to naught. The MB.156 proved another abandoned model though fitted with a Gnome-Rhone 14R series radial. The MB.157 could have proven the ultimate MB.150 form had France not fallen to Germany in 1940. The MB.157 was born from the MB.152 and fitted with the Gnome-Rhone 14R-4 radial of 1,580 horsepower.
The MB.150 Series and World War 2
World War 2 could not have come at a worse time for the French military. Much of its doctrine and command was still entrenched in a World War 1 mentality while many modern systems languished in development hampered by political maneuverings and labor strife. As such, many capable weapons were still in design phases, entering trials or undergoing slow production at limited rates at the time of the German invasion. Such a fate befell the MB.150 series as only 120 examples of MB.151 and MB.152 fighters were available and a only very few were actually air worthy, lacking key components such as propellers. Nine French Air Force fighter squadrons were eventually formed from the two production marks while the Greece Air Force managed an order of 25 MB.151 aircraft though only nine systems were ever delivered, these fighting on into April 1941.
Bloch continued strengthening the MB.150 line and this produced the MB.155 with a revised engine cowling, altered wings and a relocated cockpit moved aft to create additional internal volume for fuel. The aircraft emerged as the MB.155.C1 and entered production in 1940. However, this initiative proved too little too late for the Battle of France, and the ultimate fall of the nation in June of 1940, would severely hamper MB.155 availability for the French. The battle lasted just one month and a half and only ten MB.155s were available. An armistice signed between France and Germany gave control of military production lines to the Germans to which the lines were then used to strengthen allied Vichy French inventories. An additional 25 MB.155 aircraft were added to stocks while eight Vichy French fighter groups were assigned MB.150s. At one point, the German Luftwaffe themselves managed two MB.150 fighter groups. After the Vichy air groups were disbanded in December of 1942, MB.150s were sent to Romania to fight under the Axis banner. The Polish Air Force in exile operated MB.150 series in the war as well, rounding out the list of available operators.
In practice, the MB.150 series proved only a serviceable mount in the context of World War 2 fighting. The aircraft held enough power, stability and firepower to make a case for itself though it was not an agile beast and eventually outmoded by the excellent German Messerschmitt Bf 109 fighters. While Bloch regularly updated engine output, the design was set in a 1930s mind-set that failed to progress in time for total war. The German invasion only served to completely hamper the MB.150 series as a whole and shorten its usefulness considerably. Only the incomplete MB.157 mark was the true thoroughbred performer of the family line and this variant was taken over by the Germans (tested and completed) but never mass-produced. The prototype was eventually lost in an Allied bombing raid.
As it stood, the MB.152 marks proved the most combat-experienced of the group, accounting for nearly 190 enemy aircraft destroyed in subsequent fighting. Conversely, nearly 90 of the type were lost which showcased the series' ineffectiveness in the thick of battle. Final MB.150s were flown in anger into 1944 where liberated airframes were reconstituted for French Air Force service after Allied gains cleared regions of the Axis presence. These were poetically used against the depleted and retreating German forces for a period longer.
Fewer than 670 MB.150 series aircraft were produced in all marks and prototype/testing forms.
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