The Rolls-Royce/SNECMA M45H is an Anglo-French medium bypass ratio turbofan produced specifically for the twin-engined VFW-Fokker 614 aircraft in the early 1970s.
The VFW 614 was designed to operate over short sectors with up to a dozen flights a day. The engines were optimized for 30-minute sectors at a cruise altitude of 21,000 feet at Mach 0.65. Only a few minutes would be spent at the cruise rating and most of the flight would be at the higher climb rating or at a descent setting. The engine had a low turbine entry temperature and comparatively low rotational speed.[2]
The engine was designed to be uprated without drastic redesign. Three options were water injection (+10% thrust), improved HP turbine (+10% thrust), addition of a zero-stage to the LP compressor (+25% thrust).[2] The M45H-01 was to have a thrust-specific fuel consumption (TSFC) of 12.91 grams per kilonewton per second (0.456 pounds per pound-force per hour).[3]
The engine was developed at the time of the Rolls-Royce bankruptcy which resulted in delays in developing the engine.[4]
Variants
M45F
Civil low bypass turbofan 7,915 lbf (35.21 kN) for take-off.[5]
M45G
Military low bypass turbofan 13,200 lbf (58.72 kN) for take-off, wet.[5]
M45H
Civil medium bypass turbofan 7,880 lbf (35.05 kN) for take-off, wet.[5]
RB.410
Rolls-Royce designation for the M45SD-02 geared turbofan
M45SD-02
A derivative of the M45H-01 turbofan, designed[when?] to demonstrate ultra-quiet engine technologies, needed for STOL aircraft operating from city centre airports. A geared, variable pitch fan, replaced the first stage of the low pressure (LP) compressor. A modest fan pressure ratio, consistent with the high bypass ratio, meant a low fan tip speed could be employed. A low hot jet velocity was another major design feature. In reverse thrust, intake air entered the bypass duct, via a gap in the cold nozzle outer wall, and went through the fan, to be expelled through the intake. A small proportion of the bypass duct air entered the IP compressor, via a special diverter valve, to sustain the gas generator. Reverse thrust was obtained by the fan going through fine (rather than feather) pitch. Engine testing took place in the mid 1970s. The chief engineer of this project was David McMurtry, co-founder and Chairman of Renishaw PLC. After the prototype engine was stored,[when?] it was given to McMurtry for safe keeping at the New Mills site.[citation needed]
Davies, D. G. M.; Miller, D. C. (19–20 May 1976). A variable pitch fan for an ultra quiet demonstrator engine. 1976 Spring Convention: Seeds for Success in Civil Aircraft Design in the Next Two Decades. Royal Aeronautical Society. pp. 1–18.