Dobrynin VD-4K

Dobrynin VD-4K
Type	Four-row, turbo-compound, radial engine
National origin	Soviet Union
Manufacturer	Dobrynin OKB-36 in Rybinsk
First run	June 1950
Major applications	Tupolev Tu-85
Number built	23
Developed from	M-250

The Dobrynin VD-4K was a Soviet four-row, 24-cylinder, turbo-compound, radial engine developed after the end of World War II. It was superseded by turboprop engines before it could be widely used.

Development

The VD-4K, originally designated as the M-253K, was a development of the post-war VD-3TK (M-251K) engine. It had six monobloc banks, each with four liquid-cooled cylinders. Three blow-down exhaust, also known as power-recovery, turbines were fitted between the cylinder banks, and a geared centrifugal supercharger and a turbocharger were fitted to the engine itself, which made the VD-4K a turbo-compound engine.

Development began in January 1949 and construction of the prototype began in September of that year. The first engine was completed in January 1950 and it underwent its 100-hour tests in June. It successfully passed its State acceptance tests in January–February 1951. It was evaluated aboard a Tupolev Tu-4 bomber in 1950. It was most notably fitted to the two prototypes of the Tupolev Tu-85 bomber, but the aircraft, and its engines, was not placed into production because of the promise offered by turboprop engines of immensely more power, like the Kuznetsov NK-12 used on the Tupolev Tu-95 strategic bomber.^[1]

Applications

• Tupolev Tu-4
• Tupolev Tu-85

Specifications (VD-4K)

Data from Kotelnikov^[2]

General characteristics

• Type: 24-cylinder, four-row, turbo-compound radial engine
• Bore: 148 mm (5.8 in)
• Stroke: 144 mm (5.7 in)
• Displacement: 59.43 L (3,627 cu in)
• Length: 2.5 m (8 ft 2 in)
• Diameter: 1.4 m (4 ft 7 in)
• Dry weight: 2,065 kg (4,552 lb)

Components

• Cooling system: Liquid-cooled

Performance

• Power output: 4,300 hp (3,200 kW)
• Compression ratio: 7:1

See also

Comparable engines

• Lycoming XR-7755
• Wright R-2160 Tornado
• Pratt & Whitney R-4360 Wasp Major
• Shvetsov ASh-2
• Jumo 222
• DB 604
  

Related lists

• List of aircraft engines
  

References

Notes

1. ^ Gunston, p. 244
2. ^ Kotelnikov 2005, p. 195.

Bibliography

• Gunston, Bill (1995). Tupolev Aircraft since 1922. Annapolis, MD: Naval Institute Press. ISBN 1-55750-882-8. 
• Kotelnikov, Vladimir (2005). Russian Piston Aero Engines. Marlborough, Wiltshire: Crowood Press. ISBN 1-86126-702-9. 

External links

• VD-4
• Dobrynin Museum, including picture of a restored VD-4