Dobrynin VD-4K
The WD -4K was the final version of a Soviet aircraft engine from the OKB -36 in Rybinsk. He was until the early 1950s by W. Dobrynin developed and built at the end of the 1940s. It marked the culmination of the development of Soviet aircraft piston engines.
It is a water-cooled 24 -cylinder radial engine with four arranged in tandem ( in series) 6-cylinder stars - similar to the Junkers Jumo 222 The WD -4K was the strongest Soviet aircraft engine and drove the big strategic long-range bomber Tupolev Tu -85 of. The power of this four-stroke engine reached 3160 kW ( 4300 hp). Its power to weight ratio was favorable for large piston motors 0.51 kg / hp.
His predecessors were the M -250, M- 251TK, the M- 253K and the WD 3TK, all of which had the same 24-cylinder design. His closest competitor as a drive for the Tu -85 was at that time the Shvetsov ASch -2K with almost the same level of performance.
Technology
As its name expresses K ( " Kompressor" ), the WD -4K was not a naturally aspirated engine, but a turbocharged engine in the turbo compound engine design. His two mechanically coupled exhaust gas turbo-compressors had a variable turbine geometry, which zugutekam the response to speed and load changes and the performance at different altitudes. In addition, a turboexpander makes use of the residual exhaust gas energy, and this leads directly to the crankshaft.
The one-piece crankshaft was bent four times - for each of the four six- star once. The four cranks were added to the following angles: crank I ( 0 °) crank II ( 150 ° ) crank III (180 °) and offset IV (330 °). The mass balance was optimally, so the engine was running virtually vibration-free. This was possible because be achieved by the Hexagon arrangement (6 cylinders per star with 60 ° symmetrically arranged ) harmonic mass movements and thus free mass forces are only compensated by counterweights. Furthermore, an even firing order was achieved every 30 ° of crankshaft rotation, using Zündschemas following:
Due to the rapid development of turboprop drives the piston engines were displaced as aircraft engines soon, because turboprop reach for piston engines usually unattainable mass-specific services (power per engine ground) and have continued to be very compact dimensions. In the Soviet Union the following bombers were often NK -12 ( for example, the Tupolev Tu- 95 ) propelled by Kuznetsov, the most powerful turboprop engines ever built worldwide even today.
There are few examples of other " Hexagon" engines. They include the well - zylindrige Junkers Jumo 222 24, the 12- zylindrige Curtiss -Wright H -2120 and 12 - zylindrige Curtiss H -1640 Chieftain.
Specifications
- Engine type: Water-cooled 24 -cylinder radial engine ( 6-cylinder four -star )
- Stroke: 144.0 mm
- Bore: 148.0 mm
- Displacement: 59 455 cm ³
- Power: 3160 kW ( 4300 hp) at 2900/min
- Specific output: 72.3 bhp / liter
- Piston speed: 13.92 m / s
- Compression ratio: 7.0:1
- Mass: 2190 kg
- Diameter: 1.40 m
- Length: 2.50 m ( with turbo system and gearbox)
- Power to weight ratio: 0.51 kg / hp
- Fuel consumption: 0.160 to 0.175 kg / hp • h ( in the cruising regime in 11,000 m altitude )