Tupolev ANT 7

Design and development

Under Ivan Pogosski and guided by Andrei Tupolev, TsAGI developed the ANT-7 from the Tupolev TB-1 by scaling it down by about one third. Power for the ANT-7 was intended to be provided by two 388 kW (520 hp) – 455 kW (610 hp) Hispano Suiza engines or 313 kW (420 hp) Bristol Jupiter engines, but the prototype was powered by two 373 kW (500 hp) – 529 kW (709 hp) BMW VI engines.

The first flight of the ANT-7 took place on 11 September 1929, piloted by Mikhail Gromov. Flight tests started in March 1930 after TsAGi decided to postpone them until after the winter. That summer, the NII-VVS (Nauchno-Issledovatel'skiy Institut Voyenno-Vozdooshnykh Seel – air force scientific test institute) conducted state tests which revealed tailplane buffeting, which was alleviated by fitting enlarged elevators. The next flight encountered radiator damage and an engine failure, but in spite of this, the ANT-7 passed the state acceptance tests.

Operational history

Production aircraft were designated R-6 by the Soviet Air Force. The first production aircraft was rolled off the GAZ-22, (GAZ – Gosudarstvenny Aviatsionnyy Zavod – state aviation plant/factory), assembly line in November 1931, a year after production started. Another 410 aircraft were made during the following three years: 385 at GAZ-22 in Moscow (one of these was the R-6 Limuzin), five at GAZ-31 in Taganrog (floatplanes designated KR-6P), and 20 more at GAZ-12 in Komsomolsk-on-Amur.

The standard aircraft crew consisted of the pilot, gunner and observer and the aircraft was able to carry 113.4 kg (250 lb) of bombs for up to 965.6 km (600 mi). Some were built with floats as the MP-6, (also known as KR-6P), for maritime patrol duties. Another variant was the KR-6 (KR – Kreiser Razveyedchik – cruiser reconnaissance), which had two PV-2 machine guns and a second gunner, later relegated to training duties.

By 1935, the R-6 was becoming obsolete, and several were transferred to Aeroflot and Avia Arktika, which used them to carry passengers and cargo in Siberia before the Great Patriotic War, designated PS-7-2M17 (the "2M17" showed that the aircraft were powered by two Mikulin M-17s), or as MP-6-2M17 if floats were attached.

Variants

Data from: The Osprey Encyclopedia of Russian Aircraft 1875–1995

ANT-7

The OKB designation of the project and prototype, powered by two 544.4 kW (730 hp) BMW VI V-12 engines.

R-6

(R – Razvyedchik – reconnaissance) reconnaissance version, powered by two 544.4 kW (730 hp) Mikulin M-17F V-12 engines. first flight 1929, trials 1930.

KR-6

(KR – Kreiser Razvyedchik – cruiser reconnaissance) escort fighter version 1934, powered by two 507.1 kW (680 hp) Mikulin M-17 V-12 engines, fitted with two PV-2 machine guns and a second gunner.

KR-6P

Alternative designation of the MR-6 floatplane version.

MP-6 2M-17

(Morskoj Paassazhirskii – seaplane passenger transport) Civil floatplane version, powered by two 507.1 kW (680 hp) Mikulin M-17 V-12 engines..

PS-7 2M-17

(Paassazhirskii – passenger transport) Civil transport version PS-7 2M-17, cargo and passenger transport, first versions open cockpit, one version enclosed.

MR-6

(Morskoj razvyedchik – maritime reconnaissance) R-6, torpedo bomber version, 1932.

P-6

(Paassazhirskii – passenger transport) Civil cargo and passenger transport version.

R-6 Limuzin

Nine-seat civil transport version with a closed cockpit and a seven-seat cabin with glass windows and a luggage compartment. Powered by two 544.4 kW (730 hp) BMW VI V-12 engines. First flown in July 1933, the sole R-6L crashed on 5 September 1933 as a result of a maintenance error.

Operators

Military Operators

 Soviet Union

Soviet Air Force

Soviet Naval Aviation

Civil Operators

 Soviet Union

Aeroflot

Avia Arktika

Accidents and incidents

June 23, 1941: A Dalstroi Aviation PS-7 crashed on takeoff from Chokurdakh after the left float struck a submerged log; all five on board survived, but the aircraft was written off.

October 19, 1943: A Dalstroi Aviation PS-7 crashed on takeoff from Zyrianka due to improper luggage loading caused by crew error; all 12 on board survived, but the aircraft was written off.

Specifications (R-6)

Data from The Osprey Encyclopedia of Russian Aircraft 1875 – 1995

General characteristics

Crew: four

Length: 15.06 m (49 ft 5 in)

Wingspan: 23.2 m (76 ft 1 in)

Wing area: 80 m² (860 sq ft)

Empty weight: 3,856 kg (8,501 lb)

Gross weight: 6,472 kg (14,268 lb)

Powerplant: 2 × Mikulin M-17F V-12 water-cooled piston engines, 540 kW (720 hp) each

Performance

Maximum speed: 230 km/h (143 mph; 124 kn) at sea level 216 km/h (134 mph) at 3,000 m (9,843 ft)

Range: 800 km (497 mi; 432 nmi)

Service ceiling: 5,620 m (18,440 ft)

Rate of climb: 2.7 m/s (530 ft/min)

Wing loading: 81 kg/m² (17 lb/sq ft)

Power/mass: 0.170 kW/kg (0.10 hp/lb)

Take-off distance: – 160 m (525 ft) / 11 seconds

Landing distance: – 250 m (820 ft) at 110 km/h (68 mph)

Armament

1x 7.7 mm (0.303 in) calibre PV-2 machine gun