The Napier Eland is a British turboshaft or turboprop gas-turbine engine built by Napier & Son in the early 1950s. Production of the Eland ceased in 1961 when the Napier company was taken over by Rolls-Royce.[1]
Design and development
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 Rotodynegyrodyne. 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]
Variants
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]
The Eland has a single shaft so the silver-coloured output shaft is connected to the compressor using gears inside the red-painted gearbox. The gears reduce the compressor speed to that required for a propeller of diameter 12 to 16 feet.[10] For a helicopter application the output shaft goes into the helicopter gearbox for further speed reduction required by a large diameter rotor, 72 feet for the Westminster.
