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Subject: Перевод текста avia. Пожалуйста помогите перевести текст.The Rolls-Royce Merlin is a British liquid-cooled V-12 piston aero engine of 27-litres (1,650 cu in) capacity. Rolls-Royce designed the engine and first ran it in 1933 as a private venture. Initially known as the PV-12, it was later called Merlin following the company convention of naming its piston aero engines after birds of prey.
After several modifications, the first production variants of the PV-12 were completed in 1936. The first operational aircraft to enter service using the Merlin were the Fairey Battle, Hawker Hurricane and Supermarine Spitfire. More Merlins were made for the four-engined Avro Lancaster heavy bomber than for any other aircraft; however, the engine is most closely associated with the Spitfire, starting with the Spitfire's maiden flight in 1936. A series of rapidly applied developments, brought about by wartime needs, markedly improved the engine's performance and durability.
One of the most successful aircraft engines of the World War II era, some fifty marks of Merlin were built by Rolls-Royce in Derby, Crewe and Glasgow, as well as by Ford of Britain at their Trafford Park factory, near Manchester.[2][3] The Packard V-1650 was a version of the Merlin built in the United States, and was the primary engine used in the North American P-51 Mustang. Production ceased in 1950 after 160,000 engines had been delivered, the later variants being used for airliners and military transport aircraft.[4]
In military use the Merlin was superseded by its larger-capacity stablemate, the Rolls-Royce Griffon. Merlin engines remain in Royal Air Force service today with the Battle of Britain Memorial Flight, and power many restored aircraft in private ownership worldwide.
In the early 1930s, Rolls-Royce started planning its future aero-engine development programme and realised there was a need for an engine larger than their 21-litre (1,296 cu in) Kestrel which was being used with great success in a number of 1930s aircraft.[5] Consequently, work was started on a new 1,100 hp (820 kW)-class design known as the PV-12, with PV standing for Private Venture, 12-cylinder, as the company received no government funding for work on the project. The PV-12 was first run on 15 October 1933 and first flew in a Hawker Hart biplane (serial number K3036) on 21 February 1935.[6] The engine was originally designed to use the evaporative cooling system then in vogue. This proved unreliable and when supplies of ethylene glycol from the U.S. became available, the engine was adapted to use a conventional liquid-cooling system. The Hart was subsequently delivered to Rolls-Royce where, as a Merlin test bed, it completed over 100 hours of flying with the Merlin C and E engines.[7]
In 1935, the Air Ministry issued a specification, F10/35, for new fighter aircraft with a minimum airspeed of 310 mph (500 km/h). Fortunately, two designs had been developed: the Supermarine Spitfire and the Hawker Hurricane; the latter designed in response to another specification, F36/34.[8] Both were designed around the PV-12 instead of the Kestrel, and were the only contemporary British fighters to have been so developed. Production contracts for both aircraft were placed in 1936, and development of the PV-12 was given top priority as well as government funding. Following the company convention of naming its piston aero engines after birds of prey, Rolls-Royce named the engine the Merlin after a small, Northern Hemisphere falcon (Falco columbarius).[nb 1][9]
Two more Rolls-Royce engines developed just prior to the war were added to the company's range. The 700 hp (520 kW) Rolls-Royce Peregrine was an updated, supercharged development of their V-12 Kestrel design, while the 1,700 hp (1,300 kW) 42-litre (2,560 cu in) Rolls-Royce Vulture used four Kestrel-sized cylinder blocks fitted to a single crankcase and driving a common crankshaft, forming an X-24 layout.[10] This was to be used in larger aircraft such as the Avro Manchester.[11]
Although the Peregrine appeared to be a satisfactory design, it was never allowed to mature since Rolls-Royce's priority was refining the Merlin. As a result, the Peregrine saw use in only two aircraft: the Westland Whirlwind fighter and one of the Gloster F.9/37 prototypes. The Vulture was fitted to the Avro Manchester bomber, but proved unreliable in service and the planned fighter using it – the Hawker Tornado – was cancelled as a result.[12] With the Merlin itself soon pushing into the 1,500 hp (1,100 kW) range, the Peregrine and Vulture were both cancelled in 1943, and by mid-1943 the Merlin was supplemented in service by the larger Griffon.[13] The Griffon incorporated several design improvements and ultimately superseded the Merlin. The Merlin II and III series were the first main production versions of the engine. The Merlin III was the first version to incorporate a "universal" propeller shaft, allowing either de Havilland or Rotol manufactured propellers to be used.[19]
The first major version to incorporate changes brought about through experience in operational service was the XX, which was designed to run on 100 octane fuel.[nb 2] This fuel allowed higher manifold pressures, which were achieved by increasing the boost from the centrifugal supercharger. The Merlin XX also utilised the two-speed superchargers designed by Rolls-Royce, resulting in increased power at higher altitudes than previous versions. Another improvement, introduced with the Merlin X, was the use of a 70%–30% water-glycol coolant mix rather than the 100% glycol of the earlier versions. This substantially improved engine life and reliability, removed the fire hazard of the flammableethylene glycol, and reduced the oil leaks that had been a problem with the early Merlin I, II and III series.[21]
The process of improvement continued, with later versions running on higher octane ratings, delivering more power. Fundamental design changes were also made to all key components, again increasing the engine's life and reliability. By the end of the war the "little" engine was delivering over 1,600 horsepower (1,200 kW) in common versions, and as much as 2,030 horsepower (1,540 kW) in the Merlin 130/131 versions specifically designed for the de Havilland Hornet.[22] Ultimately, during tests conducted by Rolls-Royce aat Derby, an RM.17.SM achieved 2,640 horsepower (1,969 kW) at 36 lb boost (103"Hg) on 150 octane fuel with water injection.[23] With the end of the war, work on improving Merlin power output was halted and the development effort was concentrated on civil derivatives of the Merlin.[24]
The Merlin supercharger was originally designed to allow the engine to generate maximum power at an altitude of about 16,000 ft (4,900 m). In 1938 Stanley Hooker, an Oxford graduate in applied mathematics, explained "... I soon became very familiar with the construction of the Merlin supercharger and carburettor ... Since the supercharger was at the rear of the engine it had come in for pretty severe design treatment, and the air intake duct to the impeller looked very squashed ..." Tests conducted by Hooker showed the original intake design was inefficient, limiting the performance of the supercharger.[31][nb 4] Hooker subsequently designed a new air intake duct with improved flow characteristics which increased maximum power at a higher altitude of over 19,000 ft (5,800 m); and also improved the design of both the impeller, and the diffuser which controlled the airflow to it. These modifications led to the development of the single-stage Merlin XX and 45 series.[32]
In 1940, after receiving a request in March of that year from the Ministry of Aircraft Production for a high-rated (40,000 ft (12,000 m)) Merlin for use as an alternative engine to the turbocharged Hercules VIII used in the prototype high-altitude Vickers Wellington V bomber, Rolls-Royce started experiments on the design of a two-stage supercharger and an engine fitted with this was bench-tested in April 1941, eventually becoming the Merlin 60.[37] The basic design used a modified Vulture supercharger for the first stage while a Merlin 46 supercharger was used for the second.[38] A liquid-cooled intercooler on top of the supercharger casing was used to prevent the compressed air/fuel mixture from becoming too hot.[nb 6] Also considered was an exhaust-driven turbocharger but, although a lower fuel consumption was an advantage the added weight and the need to add extra ducting for the exhaust flow and waste-gates, meant that this option was rejected in favour of the two-stage supercharger.[39] Fitted with the two-stage two-speed supercharger, the Merlin 60 series gained 300 horsepower (224 kW) at 30,000 ft (9,100 m) over the Merlin 45 series,[38] at which altitude a Spitfire IX was nearly 70 mph (110 km/h) faster than a Spitfire V.[40]
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