The Eland was first tested in flight in 1953 in a Vickers Varsity aircraft.^[2] Further flight proving was carried out from 1955 using the first production Airspeed Ambassador 2.^[3] The Eland was dropped from production when Napier was acquired by Rolls-Royce Limited in 1961.^[2]

The only production applications for the engine were two variants of the Convair CV-240 family, the Royal Canadian Air Force Canadair CC-109 Cosmopolitan and the civil Convair CV-540. The military and civil operators had perpetual trouble with the engines which were considered complex.^[4] Due to their unreliability The Department of Transport reduced the time between overhauls.^[5] The CC-106 had its Elands replaced with the Allison T56 turboprop and the CV540 was re-engined with the Pratt & Whitney R-2800 Double Wasp piston engine. Potential production applications which were subsequently cancelled were the Westland Westminster heavy-lift helicopter and the Fairey Rotodyne gyrodyne. The Rotodyne operated as an autogyro in forward flight using the Eland turboprops. For vertical flight the rotor was driven using an auxiliary compressor clutched to each Eland. They supplied compressed air to a combustion chamber at each rotor tip.^[6]

Eland N.El.1

2,690 hp (2,010 kW) + 825 lbf (3.67 kN) residual thrust, static at sea level ICAN conditions.^[7]

Eland N.El.3

Powerplant for the Fairey Rotodyne driving the propeller and an auxiliary compressor to feed the rotor tip jets 2,805 hp (2,092 kW) + 500 lbf (2.22 kN) residual thrust, static at sea level ICAN conditions.^[7]

Eland N.El.4

3,765 hp (2,808 kW) + 610 lbf (2.71 kN) residual thrust, static at sea level ICAN conditions.^[7]

Eland N.El.6

^[8]

Eland N.El.7

The 504 adapted to helicopter / convertiplane, compressed air generator use.^[8]

Eland E.211

The 504 adapted for mechanically driven helicopter rotors.^[8]

Eland 504

(N.El.6)^[8]

Eland 508

504 with increased max continuous rating.^[8]

Turboshaft edit

• Westland Westminster

Turboprop edit

• Airspeed Ambassador
• Canadair CC-109 Cosmopolitan (CL-66)
• Convair CV-540
• Fairey Rotodyne
• Vickers Varsity (one aircraft as an engine test bed in 1954)

A turboshaft Eland is on display at the Helicopter Museum, Weston-super-Mare.^[9]

Data from Flight 29 August 1958 p.340^[11]

General characteristics

• Type: Single-shaft turboprop
• Length: 120 in (3,000 mm)
• Diameter: 36 in (910 mm)
• Dry weight: 1,735 lb (787 kg)

Components

• Compressor: 10-stage axial flow
• Combustors: 6 chambers
• Turbine: 3-stage
• Fuel type: Jet fuel

Performance

• Maximum power output: 3,500 hp (2,600 kW) (eshp - equivalent shaft horse-power - adding power from residual thrust)
  
• Overall pressure ratio: 7:1
• Air mass flow: 31 lb/s (14 kg/s)
• Specific fuel consumption: 0.595 lb/h (eshp)
• Thrust-to-weight ratio: 2.0 eshp/lb (3.3 kW/kg)

Comparable engines

• Allison T56
• Bristol Proteus
• Ivchenko AI-20
• Lycoming T55
• Rolls-Royce Tyne

Related lists

• List of aircraft engines

Notes edit

Bibliography edit

• Atlantic Canada Aviation Museum - Napier Eland 504 information sheet
• "Eland 1959" a 1959 Flight article