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Umbra A.U.T. 18 Italian contribution to the effort to create a modern fighter aircraft, which failed due to a confluence of adverse circumstances.
The designer of this aircraft, engineer Felice Trojani, was himself a very interesting personality. He was a member of the crew of Umberto Nobile on both successful flights of his "Norge" (1926), as well as on the disastrous mission of the airship "Italia" (1928), when he served as engineer and elevator operator. Both survived the crash, but fell into disfavor with the fascist government and went to the USSR, where they worked for several years on the development of Soviet airships. However, further developments in the late 1920s and early 1930s forced them both to return to Italy.
Trojani found a job as chief engineer at Aeronautica Umbra S.A. in Foligno. The head of the company was Muzio Macchi. From 1935 onwards, Aeronautica Umbra S.A. produced various Italian aircraft for other manufacturers, such as the Savoia Marchetti SM.79, Savoia Marchetti SM.81 and Savoia Marchetti SM.84 types. At this time, the Ministry of Aviation (Ministero dell'Aeronautica) is launching the so-called Project R (Progetto R) - a plan to modernize the Italian Regia Aeronautica - Caccia da Combattimento fighter air force. It envisaged the production of 3,000 fighters by 1939-40, capable of replacing the obsolete Fiat CR.32 and CR.42 biplanes. The specification required, among other things, armament of 2 large-calibre machine guns and a flight endurance of at least 2 hours. Engineer Trojani participated in this competition with his prototype A.U.T. 18. His competitors in this competition were the Caproni-Vizzola F.4, Caproni-Vizzola F.5, Fiat G.50 Freccia, IMAM-Ro-51, Macchi MC 200 Saetta and Reggiane Re 2000 Falco.
History: The first concept of the A.U.T. 18 dates back to 1934 and was certainly on the level of its time. Development work stretched over 3 years. This time was filled with demanding research, such as blowing up a number of models in a wind tunnel. The fact that the aircraft was originally conceived as a two-seater and only changed to a single-seater during the design work also took its time. This - among other things - was reflected in its greater weight and overall robustness compared to its competitors.
Muzio Macchi accepted the plans to build the fighter in 1935 and by 1936 the first prototype was completed. In the same year it received its military registration MM.363. The type designation A.U.T. 18 is made up of the manufacturer's monogram (AU), the designer's surname (T) and the wing area of the future machine (18 m2).
The flight tests started on 21 March 1939 at the factory airfield in Foligno. The factory airfield proved to be unsuitable for flight tests, so it was decided to transport the prototype to the larger Viterbo airfield 120 km away. After a difficult transport and reassembly of the machine, the first flight took place on 22 April 1939, much later than its competitors. Giovanni Roccato, the company's test pilot, sat in the cockpit. It is often said that Trojani's political troubles were behind the delay in the development of the A.U.T. 18. However, there are also opinions that multiple causes were involved in this delay - the aforementioned political difficulties of Trojani, the slow and cautious work of Trojani himself, the interference of the boss Muzio Macchi, bringing additional special requirements, and the caution of the flight pilot Roccato, who was afraid to damage or even destroy the only achievable machine.
A.U.T. 18 was moved to the larger Guidonio airfield in the Lazio area in the summer of 1939, where it took part in comparative trials with other Project R fighters. The tests were successful. On 20 February 1940, the aircraft was sent back to Foligno for further modifications, most notably receiving a better aerodynamically shaped radial engine cowl. The frontal area of the engine was reduced, the cylinder heads were given separate covers, protruding from the outline of the cowl. The propeller was given an aerodynamic cone. The machine returned to Guidonia on 21 June. The aerodynamically cleaner nose shape allowed the speed to be increased by 15 km/h, so that it now reached 489 km/h. Tests at Guidonia were completed on 12 July 1940. A total of 55 flights were made without any accidents. In addition to the chief pilot Giovanni Roccato, the aircraft was flown by Colonel Tondi, Mar. Vignoli and Captain Adriano Mantelli.
The result of the tests was that the new fighter did not offer performance significantly better than its competitors, such as the then available Macchi M.C.200, which made its first flight in 1937. The Macchi M.C.200, the FIAT G-50 Freccia and the Reggiane Re-2000 Falco won the competition and entered series production.
Deployment:The results of the test, and probably still the hostility of the politicians, led to the decision of the Reggia Aeronautica command that the prototype in its final form, although accepted into the armament of the PVO unit as of 5 November 1940, was not recommended for series production. Any further development work on A.U.T.18 was stopped.
The final fate of the prototype after it was handed over to Reggio Aeronautica is unknown. Trojani himself judged that it was taken to Germany for further testing after the Armistice, but it is more likely that it was destroyed in an air raid after being transferred to Orvieto, where it was flown over by Cap. Mantelli. Others think it was captured by the Allies for study purposes. It is known that as early as 1936 the RAF was aware of the aircraft's existence and classified it as an existing Italian type.
Design: The aircraft was designed as a single-engine, single-seat, all-metal, self-supporting low-flying aircraft. The fuselage was of triangular cross-section with rounded corners. It was made of chromoly steel tubes by autogenous welding, the covering was made of duralumin. The wing skeleton was made of the same material, but the tubes were joined by spot welding. The wing skin was made of duralumin, the covering was canvas.
The tail surfaces were made of duralumin (wing spar and ribs), the moving parts were covered with canvas, statically and aerodynamically balanced.
The undercarriage was retracted into the wings towards the fuselage, the aft wheel was also retractable. The landing gear retraction mechanism was equipped with a hydraulic system driven by pumps. The wheels were equipped with "FAST" shock absorbers.
Unlike other Italian fighters of this period, its offensive armament - two Breda-SAFAT machine guns of 12.7 mm calibre - was not mounted in the fuselage, but in the wing centroplane. The machine guns were mounted one in each wing, outside the undercarriage shafts. This arrangement put the guns outside the propeller circuit, eliminating the need to install synchronizing equipment. The machine guns carried a supply of 300 rounds for each.
The machine was powered by the common at this time twin-row 14-cylinder FIAT 80 RC. 41 radial engine, giving over 1000 horsepower, driving a three-bladed, in-flight adjustable Alfa Romeo propeller. The fuel tanks were located in the fuselage behind the cockpit.
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