Harman Patil (Editor)

Rolls Royce Clyde

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The Rolls-Royce RB.39 Clyde was Rolls-Royce's first purpose-designed turboprop engine and the first turboprop engine to pass its civil and military type-tests.


As with subsequent Rolls-Royce gas turbines, it was named after a river, the River Clyde.

Design and development

The Clyde used a two-spool design, with an axial compressor for the low-pressure section, and a single-sided centrifugal compressor as the high-pressure stage, running on concentric shafts. The first versions produced 4,030 eshp and were selected as the main engine of the Westland Wyvern TF Mk.2 strike aircraft.

The Clyde was a long engine with the axial LP compressor in front of what was, in effect, a scaled-down Derwent engine. Accessories were grouped around the axial compressor which conveniently narrowed towards the rear. Cooling for turbines and turbine bearings came from a small diffuser on the main shaft as well as tappings from the axial and centrifugal compressors. Testing of the development engines exceeded expectations with the engine soon being rated at 4,030 eshp. One problem un-earthed during testing was that damaging resonances emanated from the straight-cut spur gears in the reduction gearbox.

Despite the promising performance of the test engines Ernest Hives felt that pure-jets such as the Avon were the future and the Clyde programme was terminated, forcing Westlands to use the less than satisfactory Armstrong Siddeley Python on the production Wyverns.

Specifications (Clyde)

Data from Turbojet History and Development 1930-1960 vol.1

General characteristics

  • Type: Twin-spool turboprop
  • Length: 10.1 ft (3.08 m)
  • Diameter: 3.9 ft (1.19 m)
  • Dry weight: 2,800 lb (1,300 kg)
  • Components

  • Compressor: LP - 9 stage axial, HP - Single centrifugal stage
  • Combustors: Eleven can-type combustion chambers
  • Turbine: HP - single stage axial, LP - single stage axial
  • Fuel type: Kerosene (jet fuel grade)
  • Oil system: Pressure spray scavenge system
  • Performance

  • Maximum thrust: 1,225 lbf (5.45 kN)
  • Overall pressure ratio: 6:1
  • Air mass flow: 41.5 lb (18.8 kg)
  • Specific fuel consumption: 0.71 lb/hp/hr (0.24 kg/kW/hr)
  • Power-to-weight ratio: 1.43 hp/lb (2.08 kW/kg)
  • References

    Rolls-Royce Clyde Wikipedia

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