Bloch M.B.173

The Bloch MB.170 and its family of derivatives were French reconnaissance bombers designed and built shortly before World War II. They were, by far, the best aircraft of this type available to the Armée de l'Air at the outbreak of the war, with speed and maneuverability that allowed them to evade interception by the German fighters of the time. Although the aircraft could have been in service by 1937, debate over what role to give the aircraft delayed deliveries until 1940. 

Too few in number to make any measurable impact on the Battle of France, they continued in service with the Vichy forces after the armistice. The MB.174 will also be remembered as the aircraft flown by Antoine de Saint-Exupéry, author of The Little Prince during the campaign. His work Pilote de Guerre - translated as Flight to Arras and published in 1942 - is based on a 1940 reconnaissance mission in this type of aircraft.

In 1936, the Ministry for the Air initiated a programme of modernisation of French aviation which included a request concerning a two- or three-seat multi-role aircraft that could be used as a light-bomber or attack aircraft or for reconnaissance. A design team at the former Bloch factory at Courbevoie (which had recently become part of the nationalised SNCASO), led by Henri Deplante, proposed the MB.170, a twin-engined, low-winged cantilever monoplane.
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Operators
French Air Force ( Groupes de Reconnaissance 1/33, 2/33, 1/52 and 2/36)
French Navy
Luftwaffe (captured)

Specifications (MB.174A.3)
Data from War Planes of the Second World War: Volume Seven Bombers and Reconnaissance Aircraft

General characteristics
Crew: Three
Length: 12.23 m 
Wingspan: 17.92 m 
Height: 3.55 m
Wing area: 38.0 m² 
Empty weight: 5,612 kg 
Loaded weight: 7,175 kg
Powerplant: 2 × Gnome-Rhône 14N-20/21 14-cylinder radial engines, 772 kW (1,035 hp) each
Maximum speed: 530 km/h at 5,200 m 
Cruise speed: 460 km/h at 4,000 m 
Range: 1,650 km 
Service ceiling: 11,000 m 
Climb to 8,000 m: 11 min
Guns: 2 × fixed, forward-firing 7.5 mm (.295 in) MAC 1934 machine guns in the wings
2 × 7.5 mm MAC 1934s in the dorsal position 3 × 7.5 mm MAC 1934s on aft-firing mounts

Bombs: 400 kg of bombs - usually 8 × 50 kg bombs

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The first prototype, the MB 170 AB2-A3 No.01, equipped as a two-seat attack bomber or a three-seat reconnaissance aircraft, made its maiden flight on 15 February 1938. It was powered by two 720 kW (970 hp) Gnome-Rhône 14N radial engines and was armed with a 20 mm Hispano-Suiza cannon in the nose, two 7.5 mm MAC 1934 machine guns in the wing, with another machine gun flexibly mounted in the rear cockpit, with a ventral cupola housing either a rearward firing machine gun or a camera. The second prototype, the MB 170 B3 No.2 was a dedicated three seat bomber, with the ventral cupola housing the camera removed, a revised canopy and larger tail fins.

After many modifications it became the definitive MB.174 version. After the 50th example was delivered in May 1940, the MB.175 succeeded the MB.174 on the assembly lines in full flow. This version, a dedicated bomber, had a redesigned bomb bay capable of carrying bombs of 100–200 kg, where the MB.174 was limited to 50 kg bombs. The MB.175's fuselage was lengthened and widened to accommodate this greater capacity, but only 25 specimens were delivered before France's defeat. They were eventually used in the same reconnaissance units as the MB.174s. The MB.176 was a version with Pratt & Whitney R-1830 radial engines but which proved to have poorer performance than the MB.175. It was ordered into production in order to ease demand on the French engine manufacturers.

The Bloch MB.174 flew for the first time in July 1939 and entered in active service in March 1940. It was issued to strategic reconnaissance units where it replaced the Potez 637 that had proved too vulnerable during the Phoney war. Its first operational mission was flown by the famed pilot and writer, Cap. Antoine de Saint-Exupéry, of Groupe de Reconnaissance II/33, on 29 March 1940. The Bloch 174 appeared extremely effective in these missions as its speed and maneuverability at altitude allowed it to escape from most modern Luftwaffe fighters. 

Only 3 examples were lost to enemy fire during the Battle of France. However, like the majority of the modern equipment of the Armée de l'Air during the campaign, they arrived too late and in insufficient numbers. At the time of the armistice, most surviving MB.174s and 175s had been evacuated to North Africa. A few were recovered by the Germans and then used for pilot training. During the Vichy government rule on the French empire, MB.174s frequently flew over Gibraltar to monitor the British fleet.

In March 1941, German engineers used engines taken from MB.175s (as well as other captured aircraft) to propel the Messerschmitt Me 323 cargo aircraft, some of which actually flew with parts taken from already complete MB.175s.

After Operation Torch, as French forces split from Vichy to side with the Allies, remaining examples of the MB.170 line flew their final combat missions during the battle of Tunisia. They were replaced by reconnaissance variants of the P-38 Lightning, and used as transports and target tugs.


A final version designed for the torpedo bomber role, the MB.175T, was built in small series in 1947 and served with the Aéronavale until 1950.