B-52 Stratofortress Re-Engine - 2017
In late 2017 momentum had increased for an engine replacement in response to the USAF’s B-52H Engine Alternative Study, although the service had yet to establish a program of record or release a request for proposals. The USAF has foregone plans to reconfigure the B-52s with four engines, which would have required expensive modifications to the wing. R-R previously considered a higher thrust variant of the RB211 turbofan engine as a four-engine option on the B-52, but the service was not moving in that direction.
While rival engine manufacturer Pratt & Whitney has touted an upgraded version of its original TF33 engine to sustain the B-52 through 2050, R-R cites support from both Boeing and the USAF for a replacement rather than refurbishment.
Rolls-Royce was pitching the BR725 for the US Air Force’s B-52 bomber re-engine effort. The BR725 combines proven features from the BR 700 and Trent families and as such provides clean, efficient power for a whole new class of business jets. Compared with its highly successful predecessor, the BR710, the BR725 is more powerful, with a maximum thrust of 16,100lb, is more than 4 dB cumulative quieter, has 4 percent better specific fuel consumption and shows 21 percent improvement in NOx emissions. The advanced technology of this engine has significantly increased maintenance intervals, lowering maintenance and lifecycle cost and has eliminated mid-life inspections.
The BR725 combines proven features from the BR 700 and Trent families. The BR725 features a 50 inch diameter titanium swept fan based on world-class Trent fan design for improved aerodynamic efficiency and lower noise – a first time in the business aviation market. The 24 blades are driven by a three-stage, low-pressure turbine, for improved flow, increased efficiency, reduced noise and lower emissions. Ten-stage high-pressure compressor incorporates the latest aerodynamic improvements and five stages of blisks for improved performance and optimized weight. The two-stage shrouded high-pressure turbine uses advanced aerodynamic design and latest material for high efficiency, enhanced performance retention and longer life. A high-efficiency thrust reverser system enables increased reverse thrust and lower drag.
On 19 May 2014 Rolls-Royce annoucned the BR725 engines will power Gulfstream's new ultra-long-range business jet - the G650ER. The BR725 incorporates technology from the market-leading Trent widebody engine family and was designed with excellent fuel efficiency and ample thrust margins that support the G650ER's enhanced performance. More than 200 BR725 engines have already been built at Rolls-Royce's Dahlewitz site in Germany. The engine is part of the Rolls-Royce BR700 engine family that has accumulated more than 16 million flying hours to date and also comprises the BR710 and BR715.
R-R's 700-series engines are part of the USAF’s F130 engine family, on the Bombardier Global 5000-based E-11A Battlefield Airborne Communications Node aircraft and the Gulfstream G550-based C-37A. If the USAF moved forward with engine replacement by R-R, the company would create a new F130 engine assembly and test line in the US, while production of commercial variant, the BR725, would continue in Germany.
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