Rolls-Royce Eagle

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The Rolls-Royce Eagle was a liquid-cooled, twelve-cylinder engine - aircraft engine of the British manufacturer Rolls-Royce . It was a V-engine with a 60 ° bank angle . Between 1915 and 1928 a total of 4681 engines were manufactured in different versions.

The designation of the motor is derived in accordance with the then Rolls-Royce tradition from the birds and means Adler (English: Eagle ).

background

The engine was developed on the basis of a request made by the British Admiralty in 1914 for an aircraft engine with at least 250 hp. The first prototype of the official Rolls-Royce 250 hp, Mk. I motor designated expired in February 1915 for the first time to the test, with 225 hp at 1,650 rpm immediately -1 were achieved. This version was the first to go into production. The bore, at 114.3 mm (4.5  in ), was the same size as the Rolls-Royce Silver Ghost engine , but the Eagle had overhead valves.

construction

The steel cylinders, surrounded by a water jacket, were individually attached to the crankcase. Two magneto ignition systems were used for ignition, each supplying six spark plugs. From the Eagle VI, the ignition system consisted of four magneto ignition units, two of which supplied the double ignition of a cylinder bank (six cylinders). The ignition timing could be adjusted manually. The mixture was prepared by two or four carburetors , which were initially attached to the rear of the engine. In addition to the throttle valve, they also had a mixture setting to adjust the amount of fuel to the flight altitude and the operating condition. The carburetors were manufactured by the company under various licenses. If the engine was operated via a linkage, a spring ensured that the throttle valve was fully open when it broke. A mixture of 80% gasoline and 20% benzene was used as fuel .

The propeller speed was reduced by a planetary gear , the housing of which also absorbed the propeller thrust.

The lubrication was designed as a dry sump lubrication system with a pressure pump and a return pump, both of which were equipped with their own filters. The cooling water circulation was brought about by a water pump.

The engine was started with a starter that cranked the engine with a reduction of 1: 100. For this purpose, fuel could be injected into the intake pipes with a hand injection pump. The ignition was then turned on manually until the engine started.

Executions

Eagle I

The first series-produced version was the Rolls-Royce Eagle I. The gearbox had a reduction of 0.64: ​​1. The propeller, as well as the crankshaft, turned in the same direction, which could be clockwise or counterclockwise, depending on the requirement. Two Dobsonian carburettors with a throttle diameter of 36 mm each supplied six cylinders with mixture. The two magnetos were supplied by Bosch . The motor could be operated with both tension and compressed air screws. The braking power was 225 hp with a compression of 4.53: 1. 104 engines were manufactured between 1915 and 1916. This version was built into the Handley Page O / 100 , but also into the Felixstowe F.2A and other types.

Eagle II

The Eagle II, official name Rolls-Royce 250 hp, Mk. II , emerged from the Eagle I and differed only in the use of four Claudel-Hobson carburetors manufactured under license , also with a 36 mm throttle diameter, each with three cylinders Supplied mixture. This increased the power to 250 hp. The magneto was now supplied by Dixie, since Bosch could no longer deliver them to England. In 1916 36 pieces of this engine were produced, which were installed exclusively in the short bomber.

Eagle III

The Eagle III, officially called Rolls-Royce 250 hp, Mk. III , corresponded to the Eagle II, but the compression was increased to 4.9: 1, for which reinforced pistons were required. The magnetos were from Dixie or Watford. Between 1916 and 1917 110 engines were produced, which were used in the Airco DH4 and in the airships R31 and R32, among others .

Eagle IV

The Eagle IV, officially called Rolls-Royce 250 hp, Mk. IV , also had a compression ratio of 4.9: 1. However, two double carburetors with 2 × 38 mm throttle diameter were now used. The magnetos were again from Dixie. Between 1916 and 1917 150 engines were produced. The power was between 270 and 286 hp. These engines were also used in the R31 and R32 airships, where they replaced the less powerful Eagle III. They were also used on the R27 and R29 airships. The class 23X airships were also equipped with these engines. They were also used in aircraft such as the Handley Page O / 400 and the Handley Page HP15 .

Eagle v

The Eagle V, officially known as Rolls-Royce 275 hp, Mk. I , had four single carburettors with 38 mm throttle diameter from Claudel-Hobson - with the compression ratio of 4.9: 1 remaining the same. The magnetos were from Watford. The cam height was increased so that the power rose to 275 hp. Between 1916 and 1917 100 engines were produced and used in the Airco DH 4, among others.

Eagle VI

The Eagle VI, officially called Rolls-Royce 275 hp, Mk. II , corresponded to the Eagle V, but had a propeller gear with 0.6: 1 reduction and, for the first time in the Eagle series, a dual ignition with a total of four magneto ignition systems that came from Watford . The engine developed a maximum of 275 hp. In 1917 300 engines were produced and mainly used in the Airco DH 4.

Eagle VII

The Eagle VII, officially called Rolls-Royce 275 hp, Mk. III , corresponded to the Eagle VI except for small details and also had a maximum of 275 hp. Between 1917 and 1918, 200 engines were produced. This version was used in the Airco DH 4, but also in the Curtiss H.12 .

Eagle VIII

Rolls-Royce Eagle VIII

The Eagle VIII was the version of the engine with the largest number of units. Between 1917 and 1922, 3,302 engines were manufactured.

Compared to the Eagle VII, the compression was increased to 5.3: 1. Four carburettors were used, each with a throttle diameter of 42 mm. The carburetor arrangement was changed so that now two carburetors sat at the front of the engine, while the other two stayed in their original position at the rear. The propeller ratio was still 0.6: 1. The engine delivered up to 300 hp and was used widely.

Eagle IX

The Eagle IX was a development for civil aviation. The engine was first delivered in 1922 and remained in production until 1928. 373 pieces of the Eagle IX were made. The maximum power was 360 hp.

Compared to the military predecessor Eagle VIII, the compression has been reduced slightly to 5.22: 1. The crankshaft has been strengthened and the camshaft drive and water cooling have been improved. Four magneto ignition took care of the ignition. The mixture was prepared in two double carburettors from Claudel-Hobson, which - in contrast to the previous scheme - were now installed on the left and right at the level of the crankcase. It was fed through pipes surrounded by water between cylinders 3 and 4 into the center of the engine and then to the intake valves. The water jacket should reduce the risk of fire. All engines had left-hand crankshafts, except for those that were supplied for the Dornier Do J. As is common in Germany, they turned clockwise.

Eagle X

The Eagle X was the same as the Eagle IX, but had two magneto ignition systems from BTH (British Thomson-Houston Company), each of which supplied twelve spark plugs. Only one test run in 1922.

Eagle XV

The Eagle XV corresponded to the Eagle IX, but had a two-stage reduction gear for the propeller. In 1924 six pieces were made.

Eagle XVI

The Eagle XVI was a 16-cylinder test engine. The cylinders were attached in an X shape. At 114.3 mm, the bore corresponded to that of the first V12 Eagle, with a stroke of only 120.65 mm, which resulted in a displacement of 19.8 l. The engine had a fork-and-blade design and was supposed to produce 500 hp, but development was ended early. So it stayed with a prototype.

Technical data (Rolls-Royce Eagle IX)

  • Bore: 114.3 mm (4.5  inches )
  • Stroke: 165.1 mm (6.5 inches)
  • Displacement: 20.32 l
  • Height: 861 mm
  • Width: 1082 mm
  • Length: 1790 mm
  • Power output: 360 hp at 1800 min -1
  • Maximum speed: 2000 min −1
  • Consumption at nominal output: 109 l / h
  • Weight (including gearbox, without operating materials): 408.3 kg

swell

  • Jane's all the World's aircraft , 1919.
  • Bill Gunston: Lexicon of the aircraft engines. Motorbuch-Verlag, Stuttgart 1991, ISBN 3-613-01422-X .
  • Alec SC Lumsden: British Piston Aero Engines and their Aircraft. Airlife, Shrewsbury 1994, ISBN 1-85310-294-6 .

See also

Web links

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