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.
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).
The engine was developed at the time of the Rolls-Royce bankruptcy which resulted in delays in developing the engine.
The M45SD-02 variable geometry fan engine at the New Mills Technology Centre.
Civil low bypass turbofan 7,915 lbf (35.21 kN) for take-off.
Military low bypass turbofan 13,200 lbf (58.72 kN) for take-off, wet.
Civil high bypass turbofan 7,880 lbf (35.05 kN) for take-off, wet.
Rolls-Royce designation for the M45SD-02 geared turbofan
a derivative of the M45H-01 turbofan, designed 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, it was given to Sir David for safe keeping at the New Mills site.