Rolls-Royce Eagle

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

The name of the engine comes under former Rolls- Royce tradition of the bird world and means eagle (English: Eagle).

Background

The engine was developed on the basis of a claim by an aviation engine with 250 hp collected in 1914 by the British Admiralty. The first prototype of the official Rolls -Royce 250 hp Mk I engine was designated in February 1915 for the first time on the bench, with 225 hp could be obtained at 1650 min-1 immediately. This version finally went first in production. The bore was with 114.3 mm ( 4.5 inches ) the same size as the engine of the car model Rolls- Royce Silver Ghost, but the Eagle had overhead valves.

Construction

The by a water jacket surrounding the cylinder of steel were individually attached to the crankcase. For the two ignition Magnetzündanlagen were present who supplied six spark plugs. From the Eagle VI was the ignition system of four magnetos, two of which are double the ignition of a cylinder bank ( six cylinder) supplied. The ignition timing could be adjusted by hand. The mixture was prepared by two or four carburetors were initially attached to the rear of the engine. In addition to the throttle valve, they had a mixture setting to adjust the fuel quantity of the altitude and the operating state. The carburetors were manufactured by the company for various licenses themselves. If the motor was operated via a linkage made ​​at the break a spring for the full opening of the throttle valve. As a fuel, a mixture of 80 % gasoline and 20 % benzene was used.

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

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

The engine is started with a starter motor, by turning the motor via a reduction of 1:100. These could be sprayed with a hand injection pump fuel into the intake pipes. Ignition is then switched on by hand until the engine leapt.

Eagle I

The first mass-produced version was the Rolls- Royce Eagle I. The transmission had a reduction ratio of 0,64:1. The propeller, as well as the crankshaft turned in the same direction, which could be both clockwise and on the other hand, depending on the requirement. Two of Dobson carburetor with a throttle diameter of 36 mm served six cylinder with mixture. Both magnetos were supplied by Bosch. The engine could be operated with train as well with compressed air screws. The braking power was 225 hp at a compression ratio of 4,53:1. Between 1915 and 1916 104 engines were manufactured. This version was built approximately in the Handley Page O/100, but also in 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 by the use of four licenses made ​​Claudel - Hobson carburettors, also with 36 mm throttle diameter, the three cylinders with mixture supplied. Thus, the output rose to 250 hp. The magneto now supplied Dixie, as could be delivered no more to England from Bosch. 1916 36 pieces of this engine were produced, which were installed only in the short - bomber.

Eagle III

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

Eagle IV

The Eagle IV, official name Rolls- Royce 250 hp Mk IV also had a compression ratio of 4.9:1. Uses were now but two double carburetors with 2 x 38 mm throttle diameter. The Magneto came back from Dixie. 1916-1917 150 engines were produced. The output was 270-286 hp. These engines were also R31 and R32 used in airships, where they replaced the less powerful Eagle III. They also came with the airships R27 and R29 are used. The airships of Class 23X were equipped with these engines. They have also been used in aircraft such as the Handley Page O/400 and the Handley Page HP15.

Eagle V

The Eagle V, official name Rolls- Royce 275 hp Mk I, however, had - at the same compression ratio of 4.9:1 retarded - again four single carburetor with 38 mm throttle diameter of Claudel - Hobson. The magnetos were from Watford. The cam height was increased, so that the power increased to 275 hp. 1916-1917 100 engines were produced and including in the Airco DH Used 4.

Eagle VI

The Eagle VI, official name Rolls- Royce 275 hp Mk II, corresponded to the Eagle V, but had a propeller gearbox with 0.6:1 reduction and for the first time in the Eagle series is a dual ignition with four magnetos, originating from Watford. The engine delivered a maximum of 275 hp. 1917 300 engines were produced and mainly in the Airco DH Used 4.

Eagle VII

The Eagle VII, official name Rolls- Royce 275 hp Mk III, corresponded to the little things the Eagle VI and also made ​​more than 275 hp. 1917-1918 200 engines were produced. Using found this design in the Airco DH 4, but also in the Curtiss H.12.

Eagle VIII

The Eagle VIII was running the engine with the largest number of items. Between 1917 and 1922 3302 engines were manufactured.

Opposite the Eagle VII, the compression was raised to 5.3:1. There were four carburetors used, whose choke diameter was of 42 mm. The carburetor arrangement was changed so that now two carburetors on the front side of the engine sat, while the other two remained in the original position behind. The propellers reduction was still 0.6:1. The engine was from 300 to PS and is widely used.

Eagle IX

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

Compared to the military predecessor Eagle VIII, the compression was reduced slightly to 5,22:1. The crankshaft was strengthened and improved the camshaft drive and water cooling. For the ignition attended four magnetos. The mixture was processed in two double carburetors Claudel - Hobson, now - were planted left and right in the amount of the crankcase - unlike the previous scheme. By wasserumspülte tubes was between the cylinders 3 and 4 in the middle of the motor and then to the inlet valves. The water jacket should reduce the risk of fire. All engines were left running crankshafts, except for those which have been delivered for the Dornier Do J. They turned, as in Germany, a common practice in a clockwise direction.

Eagle X

The Eagle X corresponded to the Eagle IX possessed, however, two Magneto BTH (British Thomson - Houston Company), supplied each of which twelve spark plugs. Only a trial version 1922.

Eagle XV

The Eagle XV corresponded to the Eagle IX, however, had a two-stage reduction gearbox for the propeller. 1924 were manufactured six.

Eagle XVI

The Eagle XVI was a 16-cylinder test engine. The cylinders were mounted in an X shape. The bore corresponded with 114.3 mm of the first V12 - Eagle, with a stroke of only 120.65 mm, which had a displacement of 19.8 l was. The engine should make 500 hp, but the development was completed before a prototype was completed.

Technical data ( Rolls- Royce Eagle IX)

  • Bore: 114.3 mm ( 4.5 inches )
  • Stroke: 165.1 mm (6.5 inches)
  • Capacity: 20.32 l
  • Height: 861 mm
  • Width: 1082 mm
  • Length: 1790 mm
  • Power: 360 hp at 1800 min-1
  • Maximum speed: 2000 min -1
  • Consumption at rated output: 109 l / h
  • Weight (including gear without supplies): 408.3 kg

Swell

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