Rolls-Royce/SNECMA M45H

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The Rolls-Royce/SNECMA M45H was a medium bypass ratio turbofan produced specifically for the twin-engined VFW-Fokker 614 aircraft in the early 1970s.

The design was started as a collaborative effort between Bristol Siddeley and SNECMA.

Design and development

The single-stage fan, together with a five-stage LP compressor, was driven by a three-stage LP turbine, whilst the seven-stage HP compressor was driven by a single-stage, air-cooled, HP turbine. An annular combustor and an unmixed exhaust, with a plug-type primary nozzle, were other design features.

The engine was developed at the time of the Rolls-Royce bankruptcy which resulted in delays in developing the engine.

Variants

The M45SD-02 or RB.410 was 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...
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