Marcel Bloch MB 210. A slightly more modern bomber.
The last and best of France's trio of obsolete pre-war bombers emerged somewhat by accident. More precisely, it ended up in the Air Force by accident, as it was initially developed as a response to the specifications for a torpedo bomber issued by the French Air Force in 1932. fleet. This clearly meant a float-mounted torpedo bomber - a sea-going one. aviation preferred them, and while floatplanes were barely faster than landplanes, this made sense. It was intended to replace the wood-and-plywood biplanes of the Farman Goliath and LeO H 257bis/258/259 series.
Initially, Marcel Bloch and chief designer Maurice Roussel envisioned using the developments of the MB 200, which had just been ordered by the French Air Force, but it quickly became clear that a low-wing monoplane configuration was much more suitable for a floatplane. The fuselage remained square, like its predecessor, and for the same reasons—technological efficiency and cost—it was lengthened and widened to accommodate an internal 400 mm (670 lb) DA Mle 1926 torpedo or two cluster racks holding 8 kg (100 lb) bombs each—twice the capacity of the MB 200. Naturally, Marcel Bloch had every reason to hope that the Air Force would also show interest in the aircraft, which is exactly what happened.
Some sources claim that the design and construction of the prototypes was carried out as a private initiative and at the expense of the Société des Avions Marcel Bloch, but this is only half true—their construction was later financed by the Air Ministry. The company proposed, and representatives of the Air Ministry, Air Force, and Navy agreed to, the following construction order: the first prototype (MB 210) would be built with Gnome-Rhône 14 Kdrs/Kgrs air-cooled engines and a temporary fixed landing gear in fairings. After testing the basic characteristics, floats would be installed on the prototype, and it would be handed over to the Navy for testing in this configuration. The second prototype (MB 211) was to be built immediately with retractable landing gear and a 12-cylinder, 860-hp Hispano-Suiza 12 Ybrs V-12 engine with frontal radiators.
The first wind tunnel tests of 1/20th scale models began in October 1933. Estimated speeds were 310 km/h (198 mph) for the 210 and 330 to 350 km/h (208 to 215 mph) for the 211. Construction of the first prototype began around the same time. Since the MB 130A prototype was also being built under the BCR program at the same time, the 210 was referred to as a scaled-up version—the resemblance was indeed there. On April 27, 1934, the first MB 210 prototype was delivered from the Courbevoie factory to Villacoublay airfield. However, it didn't make its maiden flight until November 23. Its rudder featured a naval anchor and the inscription "Bloch 210 BN4 no. 1"—meaning, while it was a naval aircraft, it was actually a night bomber (Bomber de Nuit) with a crew of four. Unfavorable winter weather limited flights at Villacoublay, so the entire team focused on preparing the aircraft inside the hangars. The MB 210 resumed flying on January 15, 1935, after final weighing. The original propellers were replaced with three-bladed Gnome-Rhône variable-pitch propellers.
The first prototype of the Marcel Bloch MB 210.01
At the end of January, the aircraft returned to the hangar to correct a center-of-gravity issue discovered in flight. According to Henri Deplan, the company's future chief designer:
Initial longitudinal stability tests revealed that the aircraft was flying with a slightly rearward center of gravity. After inspection, this assessment was confirmed: the cause was a design bureau error regarding the reference chord. We needed to make the necessary adjustments. Between December and January, work was carried out to correct the defect (moving the rear gunner positions and engines forward, and slightly adjusting the wing sweep). We also took advantage of the opportunity to install improved engine cowlings and exhaust stacks, as well as a partially retractable lower rear turret.
As far as can be determined, the prototype previously had (or was planned to have) a drop-down tub, like the MB 200, with the rear hemisphere exposed only. New NACA-type engine cowlings and new wing leading edges were also installed.
On February 8, the prototype arrived at CEMA (Centre d'Essais de Matériels Aériens - Aeronautical Testing Center).
On February 14, after the traditional weigh-in, official flights began. Following stability testing, performance tests began. The maximum speed was measured at 327 km/h, and the climb time to 4000 m was 13 minutes. Furthermore, Philippe Ricco's book, Avions Marcel Bloch (Vol. 2), states that the range was 2000 km with a combat load of 2000 kg, significantly exceeding the figures usually quoted for production aircraft, although both the range and combat load appear quite realistic.
By the end of the month, the aircraft had already completed 23 flights at CEMA in just ten days. Following final testing in early April, it underwent some modifications before resuming climb measurements from April 11 to 18. Further modifications were made throughout April 1935: control surface deflection adjustments and, most importantly, the installation of a new forward cockpit canopy. It is quite possible that it was then that the 14Kdrs/grs engines were replaced by 14Kirs/jrs. Already from 14 Kirs/Kjrs. The latter pair of engines developed 850 hp for takeoff, a nominal 870 hp at 3,2 km, and briefly 940 hp at 2,6 km. The letters i in the designation denoted left-hand rotation, and j, respectively, right-hand rotation (the "r" stood for gearbox, and the "s" for supercharged).
On May 10, the aircraft was demonstrated to Air France representatives. The demonstration resulted in an order from the company for the civilian version, the MB 220 (17 were built, but with the outbreak of war, the aircraft were requisitioned). Meanwhile, on May 13, a CEMA crew ferried it from Villacoublay to the Cazaux test center for weapons testing. For nearly two weeks, flights were conducted to test the dropping of 200- and 500-kilogram bombs and test-fire the turrets, including at ground targets. Finally, the final exercise consisted of a simulated fighter attack. On May 23, the MB 210 flew from Cazaux to Pau, then to Toulouse, before returning to the Cazaux test center. It finally departed on May 25, returning to Villacoublay in two and a half hours. On the return flight, the aircraft underwent further structural reinforcement work. Several more flights were conducted in early June.
The second prototype, the MB 211, first flew on April 16, 1935. Since it was built later, changes developed on the first prototype were immediately incorporated into its design. Despite its retractable landing gear, the top speed did not exceed 316 km/h (196 mph), and other performance characteristics were not significantly different from those of the first aircraft. Later, the prototype was equipped with the infamous Hispano-Suiza 14Aa01/02 engines, producing approximately 1000 hp, turning it into the MB 212, which, however, also never entered production.
The second prototype of the MB 211
The first prototype, intended for the Navy, was now to continue the testing for which it had originally been designed. Sometime in December 1935, the aircraft was fitted with floats, becoming the MB 210 Hy No. 1. Testing began in January of the following year, continued until the spring of 1940, and was never actually completed. The seaplane's performance characteristics were predictably reduced: its maximum speed was 290 km/h at an altitude of 4 km, and its range with a 1-ton payload was only 1000 km.
Initially, the Naval General Staff planned to order a batch of eight aircraft under the designation MB 218, but later abandoned the idea. Besides the insufficient performance, one of the company's engineers cautiously hinted at personal reasons, namely, the anti-Semitism of conservative admirals. However, none of the competing twin-engine floatplanes were ordered either. The Naval General Staff limited itself to purchasing single-engine Late 298s. It seems that Marcel Bloch himself didn't expect much from these trials; when he was informed that the aircraft had been launched, he simply asked, "Oh, really? So it didn't sink?"
The same first prototype in the form of a seaplane MB 210 Hy
The situation with orders for the Air Force was much better: the first order for 80 aircraft was placed in April 1935, and a second, for 50, in May. The first production MB 210.01 took off for the first time on December 10th, powered by 14Kirs/Kjrs engines and Ratier propellers, reaching a speed of 335 km/h. The second production aircraft took to the air in April, differing only in the increased dihedral of the wing panels. All subsequent aircraft were built in virtually this configuration.
The wing structure was based on two spars. The wing was divided into four parts. Two central section sections, with parallel trailing and leading edges, were attached to the main fuselage frames. Trapezoidal consoles extended from the engine connectors. The entire wing was covered with light alloy sheets, externally reinforced with U-shaped stiffeners. The wing mechanization included ailerons and flaps (the MB 200 had only ailerons with flettners). The total fuel capacity was 2990 liters, distributed between two 300-liter fuel tanks in the engine nacelles and four located between the center section spars (two 640-liter tanks and two 555-liter tanks).
The fuselage had a rectangular cross-section with rounded corners: four angled iron (as the source states; it's clear they were referring to steel) spars, frames, and sheet metal skin reinforced with U-shaped stringers. The nose compartment housed the bombardier/navigator, also known as the front gunner, and behind him was the cockpit, where the pilot and co-pilot sat side by side. Behind the bomb bay was the radio operator/gunner's cabin with two turrets, one upper and one lower. This means that before the crew was supplemented by a flight engineer/gunner, the radio operator/gunner had to handle two machine guns and also operate the radio. True, there was a passage between the bomb racks between the cockpit and the gunner's compartment, and theoretically one of the gunners' positions could have been occupied by one of the pilots, but there is no information on this. There were complaints about cramped quarters, but this likely only applied to the gunners.
Crew accommodation
The offensive armament consisted of a 1600 kg (3,300 lb) bomb bay, two hardpoints under the fuselage, and four under the outer wings. The bomb bay could accommodate 8,200 kg (6,500 lb), 16,100 kg (2,200 lb), 32,50 kg (1100 lb), or 128,000 kg (22 lb) bombs. Two 200 kg (4,400 lb) or 500 kg (1,100 lb) bombs could be suspended in tandem under the fuselage; the underwing hardpoints were intended for small-caliber bombs (I couldn't find the exact number), but they apparently were never used. The maximum bomb load likely did not exceed 2000 kg (4,400 lb).
Modelers know it all - MB 210 with external suspension
The defensive armament consisted of three MAC Mle 1934 7,5mm machine guns with 800 rounds per gun. The machine guns had a rate of fire of 1200 rounds per minute, a muzzle velocity of 850 m/sec, and were fed from 100-round drums. The machine guns were mounted in turrets that rotated 360°, with the two rear ones partially retractable into the fuselage. Horizontal and vertical aiming was controlled solely by the gunner's muscle power. Unlike other French aircraft, the MB 200 was named Verdun, after the famous French fortress—with its three turrets, the aircraft truly resembled a fortress.
In 1933, when the aircraft's design was just beginning, the Air Force demanded that designers be able to fire machine guns in all directions, which led to this design. In the mid-1930s, views changed, and the bulky turret could have been replaced with a pintle-mounted nose mount, offering a much narrower firing angle and significantly improved aerodynamics. Eliminating this "pimple" would not only have resulted in a speed gain of at least 20-30 km/h (12-19 mph) but would also have improved the pilots' forward and downward visibility. But it seems no one was interested anymore.
The aircraft was equipped with the same outdated STAé gunsight (as on the MB 200), likely its latest modification from 1928. Very little is known about the other radio and instrument equipment, only mentioning an autopilot and a radio direction finder for navigation using ground-based radio beacons. However, the functionality of this equipment and whether it was used at all is also unknown. Of course, there was also a radio compass and a radio set, likely operating on short and medium waves and capable of both voice and Morse code communication, but again, no details are available.
The aircraft was 18,84 meters long, with a 22,85-meter wingspan and an area of 72 square meters, i.e., slightly larger than the MB 200. However, the empty weight of the aircraft, according to various sources, ranged from 5800 to 6400 kg (for the MB 200, it ranged from 4150 to 4300 kg). Meanwhile, according to all sources, the normal takeoff weight was approximately 9700 kg, and the maximum was 10200 kg. This increase in empty weight was primarily explained not so much by the increased complexity of the design, but by an increase in the safety factor from 5 to 7. Why? Because it was required by the investigative commission, which was investigating the crash of an entirely different aircraft under different circumstances. Moreover, it was required of all French companies.
Other performance characteristics: the maximum speed was either 322 km/h at an altitude of 3,5 km, or 335 km/h at an altitude of 4 km. It could reach this altitude in 11-12 minutes. The range with 1000 kg of bombs was 1000 km (according to the Dassault website) and 1300 km with 1500 kg of bombs according to https://www.passionair1940.fr/, depending on the cruising speed, which ranged from 240 to 275 km/h at an altitude of 4 km. The ceiling was up to 9900 m.
With 900–950 hp radial engines, the bomber could have reached speeds of at least 400 km/h, but unfortunately, speed was clearly not a priority for the designers and customers. Besides the excess weight and bulky turrets, which created significant drag even when retracted, there were many other factors. For example, one French aviation blogger, widely known in narrow circles of aviation enthusiasts, claimed that the external stiffeners alone "ate up" around 30 km/h, which is likely a significant exaggeration.
But the technological advancement, even with the semi-artisanal production methods, was quite high. Unofficial information suggests that just over 22000 man-hours were required to produce one aircraft. For comparison, the single-engine MS 406 required between 13000 and 20000 man-hours, and the most technologically advanced aircraft of pre-war France, the Dewoitine 520 fighter, required around 7000 man-hours.
As with the MB 200, production orders were distributed among several firms: Potez, Hanriot, ANF, Breguet, Renault, and later, in the fall of 1936, the orders were transferred to the nationalized associations SNCASO, SNCAO, and SNCAC. Of the 268 production aircraft, Bloch itself produced only 25. Hanriot also produced several aircraft for Republican Spain. Also in 1936, Romania ordered 24 aircraft.
Delays in deliveries of the Bloch 210 to the Spanish Air Force were significant: by the end of 1936, only 23 aircraft had been received, some of which were assigned to GB 11/21. Simultaneously, the first production aircraft entered service with the Spanish Republican Army. By the end of 1937, the Air Force had received 145 aircraft and re-equipped four bomber groups (GB II/21, II/19, I/12, and II/12). But problems arose.
Oddly enough, the Russian-language internet has better reviews of the MB 210 than its French or English counterparts. For example, airwar.ru: "Although the MB.210 has proven itself to be an extremely robust and reliable aircraft, virtually free of any serious defects, it has been noted that its thrust-to-weight ratio is insufficient and its engines unreliable." French-language sources are much more categorical, even using the same term "flying coffins" as for the MB 200. Of course, the 14K engines are primarily to blame, but it has also been noted that the nosed-over design doesn't provide sufficient cooling, and the fuel system "floods" during abrupt maneuvers. Of course, a certain amount of blame also lay with the pilots, who were not yet accustomed to the retractable landing gear and variable-pitch propellers.
The natural consequence was the cessation of service from September 24, 1937, to March 4 of the following year. During this period, the aircraft received more powerful and reliable Gnome & Rhône 14N 10/11 engines with a larger finned area, a takeoff power of 910 hp, and a nominal power of 940 hp at 3,9 km. Moreover, sources do not indicate any changes in performance. To say that engine-related crashes ceased would be a gross exaggeration (four aircraft crashed from July 1938 to April 1940 due to this very reason), but their number apparently decreased.
The French Wikipedia states that the MB 210 was later equipped with even more powerful 14N 20/21 engines (1135 hp for takeoff and 1020 hp nominal at 4 km), but these were likely only a few examples. This is almost the only example of re-engining in the French Air Force. And, unfortunately, the entire modernization was limited to replacing the engines—no one considered enhancing defensive armament, such as installing twin machine guns instead of single ones, or improving the aerodynamics.
In 1938, another 100 aircraft were delivered, allowing GB II/23 and I/51 to be re-equipped. As always, it suddenly became clear that there was no replacement for the MB 210. MB 131s had begun arriving in mid-38, fortunately for the Châteauroux-Déolles factory to be completed, but no one could figure out how to use them—they were poorly suited for both reconnaissance and bomber duties; ultimately, they were relegated to reconnaissance groups. Meanwhile, the long-awaited LeO 451, not to mention the Amiot 351/354, still couldn't get beyond the prototype stage. Therefore, despite their obsolescence, the MB 210s formed the backbone of French bombing operations during mobilization: 238 aircraft were in service with 12 of the 33 bomber groups. Moreover, they didn’t even have time to replace the even more ancient MB 200.
During the Phoney War, most groups transitioned to new aircraft—LeO 451, Douglas DB 7, and Amiot 351/4 bombers, or Breguet 691/693 ground attack aircraft. Consequently, combat sorties were few and far between, and their usefulness even less significant. For example, GB I/51 and GB II/51 groups managed to fly 23 and 20 sorties, respectively, in the fall of 1939 before being converted to ground attack aircraft. These were night reconnaissance missions or leaflet drops.
By May 10, 1940, MB 210s were still in service with four groups: GB II/11, GB I/21, GB II/21, and GB I/23. Interestingly, the older Amiot 143s also served with four groups but flew more combat sorties. The exact number of MB 210s is unknown, but even with the widest estimate, it's unlikely to exceed 200 combat sorties, half as many as the Amiot. Since MB 210s were also used almost exclusively at night, their combat losses were relatively small: five shot down by anti-aircraft fire and several damaged. However, non-combat losses were quite severe—at least eight aircraft crashed, and, worse, in some cases, the aircraft not only crashed but collided with others. The most serious incident occurred on May 23: MB 210 from GB I/23 landed directly on one LeO 451 and clipped another; all three burned out.
Aircraft withdrawn from the front were primarily used for training, particularly at the Bomber Training Center in Toulouse. At the time of the Armistice, there were 120 MB 210 aircraft in the southern zone, and about twenty in North Africa. Most of the aircraft were destroyed, but some continued to fly, providing crew training. During the invasion of the southern zone in November 1942, the Germans captured 37 aircraft, six of which were later transferred to Bulgaria (precise information about their subsequent use is unknown, but they were likely also used for training). None of these aircraft survived the war.
Two other countries received the MB 210: Romania and Republican Spain. As early as late 1936, Romania, then a French ally in the "Little Entente," ordered 24 aircraft (now equipped with 14N engines) to modernize its bomber force. In reality, the Royal Romanian Air Force (RRA) received between 10 and 20 aircraft. At the beginning of the war, they were used by the 82nd Bomber Squadron, particularly during the Bessarabian Campaign in 1941, reportedly with relative success (don't ask me what that means). Losses, both combat and non-combat, amounted to five aircraft. By early 1942, they were reassigned to transport duties.
Romanian MB 210
For Spain, the situation is somewhat more complex. Bloch No. 1 was delivered by air in August 1936, and at least three unnumbered examples were delivered in crates in late October 1936. These aircraft were built by workers at the Hanriot factory during overtime hours to assist the Republicans. Some sources indicate the possibility of further deliveries, but no document confirms this. Republican MB 210s were initially assigned to the Bloch squadron in the España Group, then assigned to the 11th Night Bomber Group. The last examples were used for maritime patrols.
Spanish MB 210
Information