Bloch MB.170
| Company type | Military aircraft series |
|---|---|
| Industry | Aerospace |
| Founded | 1936 |
| Founder | Henri Deplante (head of design team) |
| Headquarters | Courbevoie , France |
| Products | Reconnaissance bombers (MB.170, MB.174, MB.175, MB.176, MB.177, MB.178) |
The Bloch MB.170 series consisted of French reconnaissance bombers developed just prior to the onset of World War II. At the outbreak of hostilities, these aircraft represented the most sophisticated type in their class, offering a blend of speed, operational ceiling, and agility that allowed them to outmaneuver German fighter aircraft. Although the design was finalized by 1937, production and delivery were postponed until 1940 due to ongoing debates regarding their operational role.
Because production numbers were limited, their influence during the Battle of France was minimal; however, they continued to serve with Vichy French forces following the Armistice of 22 June 1940. The MB.174 variant became notable as the plane flown by Antoine de Saint-Exupéry during the campaign, inspiring his 1942 publication Pilote de Guerre, which recounts a mission aboard this model.
After World War II, manufacturing resumed under SNCASO with the aircraft redesignated as the SO.175, and these final versions remained in French military service until 1960.
Design and development
In 1936, France’s Air Ministry initiated a modernization effort aimed at developing a versatile two- or three-seat aircraft capable of fulfilling bombing, attack, and reconnaissance functions. The Bloch design team based in Courbevoie, headed by Henri Deplante, responded with the twin-engine, low-wing cantilever monoplane known as the MB.170.
The initial prototype, designated MB 170 AB2-A3 No.01, took to the skies on 15 February 1938, equipped with two Gnome-Rhône 14N radial engines. Its armament comprised a 20 mm Hispano-Suiza cannon, machine guns mounted on the wings, and either a flexible rear cockpit gun or a camera housed within a ventral cupola. The second prototype, MB 170 B3 No.2, incorporated several design adjustments such as an enlarged tail and modified canopy; this iteration evolved through numerous refinements into the definitive MB.174.
By May 1940, fifty units had been delivered before production transitioned to the MB.175, a bomber variant featuring an expanded bomb bay capable of carrying ordnance up to 200 kg (440 lb), compared to the MB.174’s limit of 50 kg. Only twenty-five MB.175s were completed prior to the armistice and operated alongside MB.174s within reconnaissance squadrons.
The MB.176 variant was fitted with Pratt & Whitney R-1830 engines to alleviate pressure on domestic engine suppliers but suffered from inadequate performance; only five were finished before production ceased at armistice time amid logistical difficulties, leaving approximately 200 airframes incomplete.
Powered by Hispano-Suiza 12Y31 engines necessitating extensive redesign work, the MB.177 proved underpowered and ultimately unsuitable for service. A single MB.178 was under construction when the armistice was signed; one captured airframe was transported to Rechlin for evaluation.
During German occupation, production of the MB.175 resumed for export to Germany where it was employed as a training aircraft within the Luftwaffe.
Following World War II, SNCASO recommenced production of the MB.175 for French naval forces as a torpedo bomber designated MB.175T (later known as SO.175T).
Operational history
The Bloch MB.174 made its maiden flight in July 1939 and entered operational service in March 1940 with strategic reconnaissance units, replacing the vulnerable Potez 637 during the Phoney War period. Its first combat sortie was conducted on 29 March 1940 by pilot and author Capitaine Antoine de Saint-Exupéry from Groupe de Reconnaissance II/33. The MB.174 demonstrated exceptional effectiveness due to its combination of speed and agility at high altitude, enabling it to evade most Luftwaffe fighters; only three were lost during the Battle of France. Nevertheless, like much of the Armée de l'Air's advanced equipment, deployment occurred too late and in insufficient quantities to influence outcomes significantly. By the time of armistice, most surviving MB.174s and MB.175s had been relocated to North Africa; a small number fell into German hands and were utilized for pilot training purposes. During Vichy France’s administration, MB.174s performed reconnaissance missions over Gibraltar to monitor British naval activity.
In March 1941, German engineers repurposed engines from captured MB.175s and other seized aircraft to power Messerschmitt Me 323 transport planes; some components from completed MB.175s were integrated into these cargo aircraft. After Operation Torch led French forces back into Allied cooperation, remaining MB.170 series aircraft flew their final combat sorties during the Battle of Tunisia before being phased out in favor of P-38 Lightning reconnaissance variants and reassigned roles such as transport and target towing.
Postwar production of the MB.175T (also referred to as SO.175T) resumed in limited quantities starting in 1945 and continued serving primarily as trainer aircraft until 1960.
Variants
- MB.170
- MB.170.01 – Initial prototype designed for reconnaissance missions, equipped with Gnome-Rhône 14N-06 engines.
- MB.170.02 – Second prototype intended as a light bomber, also powered by Gnome-Rhône 14N-06 engines.
- MB.171
- MB.172
- MB.173
- MB.174
- MB.174.01 – First prototype featuring Gnome-Rhône 14N-49 engines.
- MB.174A.3 – Production model with 56 units manufactured.
- MB.175
- MB.175.01 – Prototype fitted with Gnome-Rhône 14N-48 engines.
- MB.175B.3 – Second production variant; 23 produced plus an additional 56 unarmed versions supplied to the Luftwaffe.
- MB.175T
- Also referred to as SO.175T; a post-war torpedo bomber developed for the Aéronavale, with 80 units constructed.
- MB.176
- MB.176.01 – Prototype powered by Pratt & Whitney R-1830 Twin Wasp engines.
- MB.176B.3 – Production variant with five aircraft built.
- MB.177
- Single prototype utilizing Hispano-Suiza 12Y-31 inline engines.
- MB.178
- Further advancements ceased due to German occupation.
Operators
- French Air Force (including Groupes de Reconnaissance 1/33, 2/33, 1/52, and 2/36)
- French Navy (6 F squadron, 10 S squadron, and Rochefort training school)
- Luftwaffe (operated captured aircraft)