Volvo RM-12

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The Volvo RM12 is a low-bypass afterburning turbofan jet engine developed for the Saab JAS 39 Gripen fighter. A version of the General Electric F404, the RM12 was produced by Volvo Aero (now GKN Aerospace Engine Systems). Produced by Volvo Aero (now GKN Aerospace Engine Systems), the RM12 is a derivative of the General Electric F404-400. Changes from the standard F404 includes greater reliability for single-engine operations (including more stringent birdstrike protection), increased thrust, and the adoption of a full authority digital engine control (FADEC) system. [1][2] Several subsystems and components were also redesigned to reduce maintenance demands.3] The air intakes of the engine were designed to minimize radar reflection from the compression fan, reducing the radar cross section of the aircraft overall. 2] The F404's analogue Engine Control Unit was replaced with the Digital Engine Control - jointly developed by Volvo and GE - which communicates with the cockpit through the digital data buses and, as redundancy, a hydromechanical backup. Hydromechanical backup remains in the new Full Authority Digital Engine Control (FADEC) which Volvo began developing in 1996. [2] General Electric produces 50% of the engine. Elements such as the fan/compressor discs and case, compressor spool, hubs, seals, and afterburner are manufactured in Sweden, final assembly also taking place there. [2] JAS 39 Gripen IAI Nammer (as designed, not built) General characteristics Type: Afterburning turbofan Length: 4.04 m (159 in) Diameter: 0.889 m (35 in) Dry weight: Components Compressor: Axial compressor with 3 fan and 7 compressor stages Combustors: annular Turbine: 1 low-pressure and 1 high-pressure stage Performance Maximum thrust: 54 kN (12,100 lbf) military thrust 80.5 kN (18,100 lbf) with afterburner Overall pressure ratio: 27.5:1 Bypass ratio: 0.31:1 Air mass flow: 68 kg/s Specific fuel consumption: Military thrust: 23.9 mg/(N s) (0.844 lb/(lbf hr)) Full afterburner: 50.6 mg/(N s) (1.79 lb/(lbf hr)) Thrust-to-weight ratio: 7.8