Volvo delivers extra life to Gripen engine

 - November 14, 2006, 11:54 AM

Volvo Aero has delivered a number of post-certification enhancements to the RM12 twin turboshaft engine that powers the Saab Gripen. Some of these have been adopted by General Electric, whose F404 was adapted by Volvo for the single-engine Swedish fighter. The company said further improvements are possible, although its main emphasis is on developing lighter weight components for commercial airliner powerplants.

Finland and Switzerland have chosen the radial flameholder–introduced by Volvo on the RM12 in 2003–for the F404s on their F/A-18 Hornets. The U.S. Navy will evaluate it this year against GE’s improved flameholder. Volvo said its design offers four to five times the service life of its predecessor, plus a reduction in infrared signature.

The company also developed a new front frame for the RM12, with a stronger casing that reduced the number of struts by three, to 15, and used a smaller number of stiffer blades. Volvo has worked with GE to develop a full-authority digital engine control (FADEC) for the RM12, having, itself, pioneered a digital engine control for the engine. The “economy” mode on this FADEC is unique, according to the company, since other such systems offer only “combat” and “standard” settings. It could be further upgraded, for instance, to provide real-time engine condition monitoring.

The RM12 currently offers 18,000 pounds thrust in reheat. If future Gripens should require more, Volvo would study airflow improvements through the fan, turbine operating temperatures and changes to the turbomachinery. The alternative would be to adapt GE’s F414, which powers the F/A-18E/F, but “the developed RM12 would have the same thrust anyway,” the company said. It also said it is no longer considering a thrust-vectoring development of the RM12.

But military engines account for only 18 percent of Volvo’s $1 billion-plus revenues. It is a major supplier of components to all three of the big commercial engine providers, often as a risk-sharing partner with full design authority. The company specializes in lightweight fan cases and frames, compressor shells and turbine housings.

It is providing five components for the GEnx engines on the Boeing 787; on GE’s GP7000 for the Airbus 380; and on the Rolls-Royce Trent engines that compete with GE. In addition, the company is the leading supplier of rocket nozzles for commercial space launchers, with more than 1,000 delivered to date.