Rolls-Royce Gem

The Rolls-Royce Gem is a turboshaft engine developed specifically for the Westland Lynx helicopter in the 1970s. The design started off at de Havilland Engine division (hence the name starting with "G") and passed to Bristol Siddeley as the BS.360. Rolls-Royce bought out Bristol Siddeley in 1966 and after it dropped the Bristol Siddeley identity the engine became the RS.360.

Design and development
The Gem's three-shaft engine configuration is rather unusual for turboshaft/turboprop engines. Basic arrangement is a four-stage axial LP (Low Pressure) compressor, driven by a single stage LP turbine, supercharging a centrifugal HP (High Pressure) compressor, driven by a single stage HP turbine. Power is delivered to the load via a third shaft, connected to a two-stage free (power) turbine. A reverse flow combustor is featured.

The Gem 42 develops 1000 shp at Take-off, Sea Level Static, ISA, but the Maximum Contingency Rating (MCR) is 1120 shp.

Until recently all versions of the Lynx have been Gem powered. However, now that Rolls-Royce own Allison, they have been marketing the more modern LHTEC T800, developed jointly with Honeywell.

Applications

 * Agusta A129 Mangusta
 * Westland Lynx

Engines on display

 * East Midlands Aeropark
 * Midland Air Museum
 * The Helicopter Museum (Weston)
 * 111 (Sunderland) Squadron ATC
 * South Yorkshire Aircraft Museum