BMW Rolls-Royce has defined the configuration for a new 35-62kN (8,000-14,000lb)- thrust engine family to rival the General Electric CF34-8C. A military-trainer engine is one of the potential applications.

A final launch decision on the new BR500 engine family, which comes in below the thrust range of the BR700, depends on finding a risk-sharing partner - possibly even a programme leader.

Ganter Kappler, BMW R-R research and development director, says that the engine core has three axial-compressor stages, followed by a "diagonal" compressor stage, with a single-stage turbine. The diagonal compressor works on the same principle as a centrifugal compressor, but allows a higher mass-flow rate, generating more power.

The engine uses technology derived from BMW R-R's work on the T312 and AlliedSignal RE220 auxiliary power-units. Derivatives of the new engine could include a reheated version to power military trainers, says Kappler.

South Korea has already considered the engine as a possibility for its KTX-II jet-trainer programme (Flight International, 7-13 June).

A diagonal compressor is also incorporated in the turbojet engine forming part of the BMW R-R/Microturbo LCT 85 integrated propulsion-module (IPM) proposed for the French/German/Italian Polyphem fibre-optic guided missile.

As well as the power plant, the IPM includes a fuel pump, start cartridge, ignitor, alternator, power-conditioning unit and controls. BMW R-R is responsible for the 1kN engine's inlet, compressor and diffuser.

A decision on selection of the Polyphem power plant is expected in September, says Kappler.

The LCT 85 is in direct competition with the model 325M power plant from Teledyne Ryan Aeronautical, which will also be in the 1kN class.

BMW R-R has also been investigating thrust classes above the BR700 family's range. Managing director David Evans says that it is possible to increase the aerodynamic flow of the BR700 core by 20% to achieve a 110kN rating. Moves in this direction have been stymied by R-R's role in the rival International Aero Engines V2500.

At the same time, Kappler says the company has decided to go ahead with a prototype of its 80-90kN BR715, to be run by the end of 1996.

Source: Flight International