The Ro 37 reconnaissance biplane was the first aircraft designed by the Industrie Meccaniche e Aeronautiche Meridionali (IMAM) to see widespread use. From 1934, when it first appeared, until 1943 or 1944, the aircraft and its derivatives served wherever Italian forces were found, both on land in Italy, Spain, France, Libya, the Balkans, Ethiopia, and Somalia and at sea with the ships of the Italian fleet. It was, by contemporary Italian standards, a successful contender on the export market as well, being adopted by Afghanistan, Ecuador, Hungary, and Uruguay. Yet it is today little known to many aviation enthusiasts.
The Ro 37 was not the first successful aviation venture by this onetime, Neapolitan railway-car manufacturer. In 1925, Meridionali had managed to purchase the Italian license for Fokker's extremely successful C.V, a single-engined observation and light-bombing biplane designed for a wide range of alternative engines. IMAM's version of the C.V was powered by a 500-hp Alfa Romeo-built Bristol Jupiter radial engine and called the Ro 1. It became the standard, general-purpose biplane of the Regia Aeronautica Italiana during the early 1930s. Ro 1s saw extensive service during Italy's conquest of Ethiopia, where they proved invaluable for machine gunning and gassing the Negus' largely defenseless feudal infantry.
The Regia Aeronautica's happy experiences with the Ro 1 seem to have given IMAM the inside track when it came to a replacement. But the planned successor, the three-seat, IMAM-designed Ro 30 of 1932, was not a resounding commercial success, being ordered in only limited quantities by the Italian service. In all likelihood, the 10% power increase offered by its 550-hp, Alfa/Bristol Jupiter was not enough to tempt the air force away from the still entirely satisfactory C.V/Ro 1. While the Ro 30 bettered the earlier aircraft's 19,680-ft (6055-m) service ceiling by almost 5000 ft (1538 m), it's top speed was actually slightly lower (155 mph vs. 158 for the Ro 1).
When the Ro 37 appeared in 1934, however, it at last offered a significant step forward technologically and a useful increase in performance. So much so, in fact, that it was originally intended for a dual reconnaissance and two-seat fighter role. Powered by the new FIAT A.30 RA, a 600-hp, liquid-cooled V-12 that was both more powerful and more streamlined than the Jupiter, the Ro 37 could reach a top speed of 199 mph (332 kph) at 13,120 ft (4037 m), could land at 67 mph (112 kph), and had a service ceiling of 21,976 ft (6762 m). Range was marginally reduced compared with the Ro 1: 726 miles (1212 km). Pleased with these results, the Regia Aeronautica ordered about 200 aircraft, a large order for the time.
The Ro 37 was an all-metal two-seater with fabric-covered wings, tail and fuselage, and an aluminum paneled nose section. A streamlined, articulated, split-axle undercarriage was fitted, with closely spatted wheels. The aircraft weighed 3432 lbs (1560 kg) empty and 5269 lbs (2395 kg) fully loaded. It spanned 36 ft 4 in (11.2 m) and had a wing area of 338 sq ft (32 m²). It was 28-ft 3-in (8.7-m) long.
The Ro 37 was intended primarily for the corps-level reconnaissance role, but it was also expected to operate in a ground-attack, light-bombing, and colonial air-policing capacity, as required. It was thus comprehensively equipped, for the period, and heavily armed. IMAM catered to the primary long-range reconnaissance mission by providing unusually comfortable, well-lighted accommodation for the navigator and his chart table in the space between the two open cockpits. This space was lit by an overhead canopy, which also shielded the rear gun mount from the slip stream, and by large, glazed side windows that could be slid open when desired. For rear defense, the aircraft carried a 7.7-mm Lewis or Breda machine gun on a simple ring mount (a hydraulic ally actuated Breda turret was considered, but never fitted). Two synchronized, 12.7-mm Breda-SAFAT heavy machine guns were mounted under the engine decking forward—an unusually heavy armament at a time when most similar aircraft mounted a single, forward-firing 7.7-mm gun. Underwing racks could carry up to twelve 12- or 15-kg bombs.
Like the Ro 1, the Ro 37 was designed to accomodate a range of engines, an air-cooled radial-engined version, the Ro 37bis, succeeded the FIAT-powered aircraft on the production lines. The Ro 37bis was powered by either of two engines, the 560-hp Piaggio P.IX RC40 or the 700-hp Piaggio P.XR, both 9-cylinder radials rated for maximum output at a lower altitude than the FIAT A.30. With the former, the Ro 37bis was marginally faster than the Ro 37, reaching a maximum of 205 mph at 16,400 ft (50046 m), and had a substantially better ceiling, 23,616 ft (7266 m). With the latter, the Ro 37bis had the same maximum speed as the Ro 37, 199 mph (332 kph), but reached it at 6560 ft (2019 m). Service ceiling was reduced to 20,664 ft (6358 m). No doubt this engine was best suited for aircraft used primarily for low-level tactical and colonial roles, while the P.IX. was better suited to the original strategic reconnaissance mission. About 200 were ordered.
Dimensionally, the Ro 37bis differed little from the Ro 37. The aircraft was marginally shorter overall at 28 ft 1 in (8.6 m). 
Both radial-powered aircraft were slightly heavier than the V-12 version. Empty and loaded weights with the high-altitude P.IX engine fitted were 3498 lb (1590 kg) and 5335 lb (2425 kg), respectively. With the P.XR, empty weight was 3454 lb (1570 kg) and loaded weight was 5291 lb (2405 kg). The Ro 37bis carried the same equipment and armament as the Ro 37.
The Ro 37bis first saw combat in Spain, where it was a favorite of the specialist, cadena ("chain") ground-attack units, especially the Spanish Fascist Grupo 4-G-12 and the 120
Approximately 283 Ro 37 and 200 Ro 37Bis models were on strength when Italy entered WW2, though only about 100 of the Ro 37s were serviceable at that point. During Italy's hurried and belated invasion of France in 1940, Ro 37s operated in their original reconnaissance role, largely unhampered by the few French fighters that were still operational after the Luftwaffe onslaught. They also spearheaded the ill-fated Italian invasions of Yugoslavia and Greece, operating from bases in Italian-controlled Albania. The FIAT-engined Ro 37s were, in fact, retained in this area long after they had vanished from the other theaters. They flew antipartisan patrols and strikes in the Balkans up until the Italian capitulation in 1943.
The Ro 37bis was widely used in Italy's African possessions during the early years of the war. The isolated, aircraft- and munitions-starved forces in Italian East Africa (Ethiopia and Somalia) used their few Ro 37s for everything from bombing to fighting, alongside FIAT CR 32 and CR 42 fighters, until overwhelmed by British forces advancing from Kenya and the Sudan. In North Africa, the type was frequently encountered at first, but the increasing sophistication of the opposing fighters and the harsh operating conditions rapidly reduced their numbers.
The Regia Marina, or Italian Royal Navy, used the basic Ro 37bis design as the basis for its standard, catapult-launched, shipboard aircraft of WW2, the Ro 43 observation floatplane and the Ro 44 floatplane fighter. The fuselages of these aircraft were almost identical in appearance to those of the two-seat and single-seat versions of the 37bis. But a gulled upper and inverse-gulled lower wing replaced the standard wing cellule. A single main float on the center line and two balancer floats on the lower wings replaced the wheel undercarriage of the land aircraft. Armament was reduced to a single 7.7-mm synchronized machine gun and a single similar weapon in the rear cockpit. The airplane weighed 3916 lb empty and 5280 lb loaded. Maximum speed was 186 mph at 8200 ft, the service ceiling was 21,648 ft. It could stay in the air for up to 8.5 hours and had a range o 932 miles. The wings spanned 38 ft and had an area of 359 sq ft. The aircraft was 31 ft 10 in long.
The Italian navy made little operational use of the two-seat Ro 43 reconnaissance-fighter. About 125 were built. Of these, 105 were on strength and 42 were serviceable when the war began. 48 remained at the capitulation in 1943, but only 22 were flyable. The aircraft served with the 2
Of all the nations that experimented with catapult launching o fighters from capital ships in the 1920s, only Italy persisted with the practice until 1943. minimally navalized Reggiane Re 2000 monoplanes offered superior performance, but had to ditch or divert to land for recovery. So, for the rest of the war, the bulk of the navy's organic fighter protection was provided by the wholly obsolete Ro 44 fighter biplane.
