The Bloch MB.210 BN5 five-seat night bomber was the most numerous French bomber at the start of the Second World War, although it was already in the process of being replaced by more modern aircraft, and had declined in importance by the start of the Battle of France in May 1940.
The Bloch 210 was developed in response to two separate specifications issued in 1932 - one from the French Naval Air Arm for a torpedo-bomber to replace the Farman F.60 Goliath floatplane and one from the Army (issued just before the formation of the separate Armée de l'Air) for a heavy night bomber to replace the Lioré & Olivier LeO 20 BN5 (five seat night bomber).
Avions Marcel Bloch decided to produce a single aircraft to satisfy both of these requirements. Loosely based on the Bloch 200 the result was a low winged twin engined monoplane, with a rectangular fuselage, a thick wing, and either floats or a fixed undercarriage. Three manually operated gun turrets, each with a 7.5mm machine gun, provided defensive firepower, and 3,527lb (1,600kg) of bombs could be carried in the bomb bay.
Two prototypes were constructed at about the same time. The second, powered by inline engines, became the Bloch 211 and then was re-engined to become the Bloch 212, neither of which entered production. The first prototype, the Block 210 No.1, was powered by two 800hp Gnône & Rhône 14kdrs/Kgrs Mistral Major air cooled radial engines, and had a fixed undercarriage. Work began during 1933, and the prototype was complete by the summer of 1934. On 27 July 1934 it was taken by truck to the testing ground at Villacoublay, where work continued, until on 24 November 1934 the aircraft made its maiden flight.
Over the winter of 1934-35 a number of change were made to the aircraft. The tail was redesigned, the dorsal turret was moved, the outer wing panels had the angle of sweepback increased and a retractable ventral turret was added. Official flight tests began on 14 February 1935, and in March the aircraft underwent armament trials. In April and May1935, after these tests had been completed, the Armée de l'Air placed orders for 130 Bloch 210s.
Development work continued, both on the prototype and on the early production machines. In January 1936 the prototype made its maiden flight as a float plane, from Berre Lake near Marseille, but the floatplane version didn't enter production.
The first production aircraft flew on 10 December 1935. It was the first to feature a semi-retractable undercarriage, with the wheels folding backwards along the engine nacelles, and was powered by 870hp 14Kirs/ Kjrs radial engines, giving it 140hp more power than the prototype. The second production aircraft made its maiden flight in April 1936, with increased dihedral in the outer wing panels to improve the aircraft's stability in flight. Most production aircraft were given more powerful 14N 10/11 engines, adding another 80hp to the total.
As with all French aircraft of this period deliveries were slower than expected, and only 23 were completed by the end of 1936. When production ended early in 1939 a total of 253 aircraft had been completed, including ten for Romania.
In September 1939 a total of 238 Bloch 210s equipped twelve bomber groups in six Escadres de Bombardment. Two (GB I/19 and II/19) were temporarily in North Africa while the remaining ten were in France - GB I/11, II/11, I/23 and II/23 were at Toulouse, GB I/12 and II/12 were at Rheims, GB I/21 and II/21 were at Bordeaux and GB I/51 and II/52 were at Tours. This made the Bloch 210 the most numerous bomber aircraft in French service, but the Armée de l'Air considered it to be obsolete, and ordered all of the units to the south of France to convert to more modern aircraft (the LeO 451 and Amiot 354).
On 10 May 1940, when the German offensive in the west began, only GB I/23 at Istres was still fully equipped with the Bloch 210, while GB I/21 and GB II/21 were in the process of converting away from the type, and still had enough of the older aircraft to take it into combat.
GB I/23 was the first into action, using their aircraft on night operations against the advancing German columns in Belgium and France, before being withdrawn on 1 June to convert to the LeO 451. GB I/21 and II/21 entered the battle on 18 May from La Ferté-Gaucher, also operating against German ground forces. Over the next few weeks the two groups lost ten aircraft during these night missions.
After the fall of France the Bloch 210 was retired, and wasn't used to equip any combat units of the Vichy Air Force in metropolitan France, Syria or North Africa, even though 99 aircraft survived the war in France and twenty in North Africa. The last Bloch 210s to be used in French service were six aircraft converted to serve as navigation trainers during 1942.
The last Bloch 210s to see combat were the ten aircraft ordered by Romania. On 22 June 1941 the Romanians took part in the German invasion of the Soviet Unit, and the Blochs took part in the attack. Somewhat surprisingly, despite their being used on both day and night missions the now somewhat elderly Bloch 210s only suffered five losses, some caused by accidents, in nine months of combat that only ended in March 1942.
Engine: Gnôme & Rhône 14N 10/11 14-cylinder air-cooled radial engines
Power: 910hp each
Crew: 5 (pilot, co-pilot/ navigator, nose gunner, radio operator/ ventral gunner and dorsal gunner)
Wing span: 74ft 10in (22.8m)
Length: 62ft (18.9m)
Height: 22ft (6.7m)
Empty Weight: 13,206lb (5,990kg)
Fully loaded Weight: 22,487lb (10,200kg)
Max Speed: 200mph (322km/h) at 11,483ft (3,500m)
Service Ceiling: 32,480ft (9,900m)
Range: 1,056 miles (1,700km)
Armament: Three 7.5mm MAC 1934 machine guns in nose, dorsal and ventral turrets
Bomb-load: 3,537lb (1,600kg) - two 500kg, eight 200kg, thirty-two 50kg or one hundred and twenty eight 10kg bombs