An ANT-9 fitted with a ski undercarriage and powered by M-26 radials.

Numerically the most important of Tupolev’s designs up to the mid 1930s was the ANT-9 tri-motor transport (Russian: Туполев АНТ-9), the first of which was completed on April 28, 1929. As with other Tupolev aircraft of the period, there were strong Junkers influences apparent in the design, which had an all-metal structure with corrugated skinning. Unlike Junkers aircraft, however, the ANT-9 was a high-wing monoplane, and made extensive use of the Russian-developed Kolchugalumin alloy. The divided main undercarriage members were reminiscent of Fokker practice, with steeltube Vs hinged at their open ends to the lower fuselage, and supported at their outboard ends by telescopic legs running up to the centre section of the three-part wing structure.

The prototype ANT-9 was powered by three 230-hp Gnome-Rhone (Bristol) Titan radials, and was slightly smaller than production aircraft, with a span of 23.7 m (77 ft 9 in) but a length of 17 m (55ft 9 ¼ in). This prototype was fitted out with the standard accommodation for two flight crew in an enclosed cockpit forward of the wing, seating for nine passengers in the centre fuselage, and in the rear fuselage a lavatory and baggage hold. The type returned a maximum speed of 209 km/h (130 mph) and had a range of 1000 km (621 miles). Between June 6 and 12, 1929 it made an exhibition tour in the USSR; then between July 10 and August 8, 1930, named Krilya Sovetov (Wings of the Soviets) for the occasion, it made a 9037-km (5615mile) tour of western Europe.

The ANT-9 was produced in two forms, the first similar in size to the prototype but powered by three 300-hp M-26 radials, and the second with three 365-hp Wright Whirlwind J6 radials. This latter model spanned 23.85 m (78 ft 3 in) and was 16.65m (54ft 7 ½ in) long, and was at 205km/h (127 mph) some 20km/h (12 mph) faster than the model powered by the M-26, though range fell by 300 km (186 miles) from 1000 km (621 miles).

In 1932 there appeared the PS-9 variant, powered by a pair of licence-built BMW VI V-12s, named M-17 by the Russians. Despite the increase in weight from 6000 kg (13 2281b) to 6200 kg (13 6691b), the PS-9 had much superior performance due to the greater power available and the reduction in drag effected by the elimination of the third engine. All ANT-9s and PS-9s could operate from ski undercarriages in winter.

ANT-9-M-17 (PS-9)

Type: medium-range transport

Maker: Tupolev Design Bureau

Span: 23.73m (77ft 10 ¼ in)

Length: 17m (55ft9 ¼ in)

Height: 5.5m (18ft ¾ in)

Wing area: 84m2 (904sqft)

Weight: maximum 6200 kg (13 669Ib); empty 4400 kg (97001b)

Powerplant: two 680-hp M-17 water-cooled V-12 engines

Performance: maximum speed 215km/h (l34mph); range approx 1000 km (621 miles)

Payload: 810kg (1786lb); seats for up to 9 passengers

Crew: 2

Production: approx 70