The SM.85 was part of a programme by the
Regia Aeronautica to produce a twin-engine monoplane dive bomber based on the theories developed over the previous 20 years by the American
General Billy Mitchell, that were enthusiastically adopted by Colonel Amedeo Mecozzi (who also developed the
Breda Ba.64 and its derivatives) for attack aircraft. The resulting aircraft, constructed of wood, had a wing set in an upper-middle configuration, a rectangular cross-section
fuselage, retractable
undercarriage and a fixed tail wheel, and was powered by two
Piaggio P.VII C.35 engines. The wings, made totally of wood, had three
longerons, with fabric covering. The aircraft was designed to give the pilot the best possible forward view, with a transparent panel built into the
cockpit floor.' The SM.85's useful payload was 1,150 kg (2,540 lb), including the possibility of fitting a 12.7 mm (0.5 in) machine gun with 300-500 rounds. The aircraft was capable of also using its
flaps as
airbrakes for diving attacks, a notable characteristic of this aircraft. The bomb load was carried in a parallelogram-shaped section mounted under the fuselage. The SM.85 was capable of carrying a 500 kg/1,100 lb bomb (or an 800 kg/1,760 lb bomb, the heaviest weapon in the Italian aviation arsenal, but only on very short range missions). At maximum payload, with a 4,000 kg (8,820 lb) takeoff weight, the climb rate was 20 min to 5,000 m (16,400 ft), but freshly started engines did not produce their theoretical maximum power and the aircraft was usually much slower than this. The takeoff needed 433 m (1,421 ft), and the landing 415 m (1,362 ft). Ceiling was 6,000-6,500 m (19,690-21,330 ft) and 756–827 km (470-514 mi) range. Maximum speed was 367 km/h (288 mph) at 4,000 m (13,123 ft). The fuel capacity was 1,078 L (285 US gal), contained in four
self-sealing fuel tanks. At the maximum payload with a 500 kg (1,100 lb) bomb, it was incapable of taking off with a full fuel load (around 730 kg/1,610 lb), so this was used only on ferrying missions. The first prototype was tested in December 1936, and in spite of its insufficient speed and the disappointing rates of climb, the
Regia Aeronautica felt there was sufficient room for development and ordered the SM.85 into production. Despite some improvements, critical deficiencies continued to be experienced during test flights by the
Reparto Sperimentale Volo a Tuffo. These revised aircraft were disappointing as dive bombers in almost every aspect, with the most serious problems encountered being frequent uncontrollable spins, extremely slow climb rate after a dive, and instability during the dive. Production of the aircraft was halted, and the 34 produced up to that time were organised as 96°
Gruppo Tuffatori (96th Independent Dive-Bomber Group). Although the SM.85 programme could be viewed as Savoia-Marchetti's worst mistake in wartime, this dive bomber was considered a threat by the British. They considered the possibility of suicide missions made with this aircraft against their ships, having mistaken the meaning of
tuffatori. The SM.85 was essentially made into a "
training dive-bomber" as it was never really suited to being an operational machine. Its engines were not powerful enough to achieve a satisfactory performance, and even when the SM.86 was developed, with much improved engines, it was too late. One SM.85 was modified into a two-seat trainer version. This was developed within a programme that lead to the advanced
SM.93, another interesting and unusual aircraft, with high-speed performance and a prone pilot position. Development began too late to be put into production, as with almost all other Savoia-Marchetti "series 90s" projects. In retrospect, the SM dive bombers were a failure. ==Operational history==