Tupolev Tu-85

Tu-85
File:Tu-85front.jpg
Role	Heavy bomber
National origin	Soviet Union
Manufacturer	Tupolev
First flight	9 January 1951
Status	Prototype
Number built	2
Developed from	Tupolev Tu-4

The Tupolev Tu-85 (USAF/DoD reporting name 'Type 31', NATO reporting name Barge) was a Soviet prototype strategic bomber based on the Tu-4, an unlicensed reverse engineered copy of the Boeing B-29 Superfortress. It was the ultimate development of the B-29 family, being over 50% heavier than its ancestor and had nearly double the range. Only two prototypes were built before the program was canceled in favor of the Tupolev Tu-95 bomber which was much faster and had the same range.

Development

Neither the Tu-4, nor the Tupolev Tu-80 were true intercontinental strategic bombers as they lacked the range to attack the United States from bases in the Soviet Union and return. The Tu-85 was designed to achieve the necessary range by use of more powerful and fuel-efficient engines, a redesigned wing to increase the lift/drag ratio and the addition of more fuel. A large number of engines were considered before settling on the 4,500-horsepower (3,400 kW) Shvetsov ASh-2K, essentially two air-cooled ASh-82 radial engines paired together and the liquid-cooled 4,300-horsepower (3,200 kW) Dobrynin VD-4K radial. Both engines were given turbochargers and power-recovery turbines which converted them into turbo-compound engines. The Shvetsov design was preferred, but was not yet mature enough for use, and the VD-4K was selected. A lot of effort was put into refining the design of the wing in collaboration with TsAGI. It had an aspect ratio of 11.745 and a taper of 2.93 for optimum lift at high-altitudes. The Tu-85 carried 63,600 litres (16,800 US gal) of fuel in 48 flexible tanks.

Much of the armament and equipment was derived from those of the late-model Tu-4, including the four remotely controlled dorsal and ventral turrets and the tail turret, each with two 23 mm (0.91 in) Nudelman-Rikhter NR-23 cannon. But the Tu-85's tail turret had an Argon ranging radar and each of the two bomb bays was enlarged to hold a 9,000 kg (20,000 lb) FAB-9000 bomb.

Actual design work began in August 1949 and was ratified by a directive from the Council of Ministers dated 16 September that required the first prototype to be ready for manufacturer's tests in December 1950. Construction of the first aircraft began in July 1950 and was completed in September. It first flew on 9 January 1951 and the manufacturer's tests lasted until October 1951. On 12 September the first prototype flew 9,020 km (5,600 mi) with a bomb load of 5,000 kg (11,000 lb) and landed with enough fuel remaining to have covered 12,018 km (7,468 mi). The second prototype, sometimes referred to as the 85D (Russian: dooblyor) or 85/2, incorporated the lessons learned from the first aircraft, including revision and reinforcement of the airframe and a variety of changes to its equipment and systems. It was first flown on 28 June 1951 and its trials lasted until November 1951. Series production was approved on 23 March 1951 at three factories where it would succeed the Tu-4 on the production line, but this was reversed later in the year and the program was canceled - Korean War, during which the Soviet MiG-15 was successfully brought down the American B-29 showed that piston aircraft for military use is not perspective. Priority was given to the higher performance turboprop Tu-95 'Bear'.

Specifications (Tu-85/1)

Data from Gordon, OKB Tupolev: A History of the Design Bureau and its Aircraft

General characteristics

• Crew: 11–12
• Length: 39.306 m (128.96 ft)
• Wingspan: 55.96 m (183.6 ft)
• Height: 11.358 m (37.26 ft)
• Wing area: 273.6 m² (2,945 ft²)
• Empty weight: 54,711 kg (120,364 lb)
• Loaded weight: 76,000 kg (167,200 lb)
• Max. takeoff weight: 107,292 kg (236,534 lb)
• Powerplant: 4 × Dobrynin VD-4K turbo-compound radial engines, 3,200 kW (4,300 hp) each

Performance

• Maximum speed: 638 km/h (344 kn, 396 mph)
• Range: 12,000 km (6,500 nmi, 7,457 mi)
• Service ceiling: 11,700 m (38,376 ft)
• Rate of climb: 17 m/s (3,280 ft/min)
• Wing loading: 277 kg/m² (57 lb/ft²)
• Power/mass: 170 W/kg (0.10 hp/lb)

Armament

Guns: 10 × 23 mm Nudelman NR-23 cannons, two each in four turrets plus tail barbette

Bombs: up to 18,000 kg (40,000 lb) of bombs

See also

• Tupolev Tu-4
• Tupolev Tu-70
• Tupolev Tu-75
• Tupolev Tu-80
• B-29 Superfortress
• B-50 Superfortress

References

Bibliography

• Gordon, Yefim; Rigamant, Vladimir (2005). OKB Tupolev: A History of the Design Bureau and its Aircraft. Hinckley, England: Midland Publishing. ISBN 1-85780-214-4. 
• Gunston, Bill (1995). Tupolev Aircraft since 1922. Annapolis, MD: Naval Institute Press. ISBN 1-55750-882-8. 

External links

• Tu-85 by A.N. Tupolev (NATO "Barge")