H-92 Powers Up
General Electric has agreed to develop a new derivative of its CT7-8 engine to boost the power available to the Sikorsky H-92 Superhawk, a military version of the S-92 helicopter now vying with a version of the EH-101 for the privilege of transporting U.S. Presidents.
Replacing the commercial S-92's CT7-8As with the upgraded engines will increase the power available to the twin-engine helicopter by about 960 hp. and raise the rotorcraft's payload by about 4,000 lb., to roughly 11,500 lb., when hovering out of ground effect under 4,000-ft. and 35F takeoff conditions. The new CT7-8C engines will significantly improve the "hot/high" operating characteristics of the H-92 and give it an important payload and range advantage over its competitor, Sikorsky's Paul W. Martin noted. He is the company's senior vice president for government and advanced development programs.
Sikorsky is positioning the H-92 as a military utility/transport aircraft that also can be used for combat search-and-rescue or antisubmarine warfare. The company is pitching the H-92 in three competitions: the U.S. presidential, or VX mission; the U.S. Air Force combat search-and-rescue replacement program; and the Canadian Maritime Helicopter Project. Approximately 28 aircraft would be procured in the Canadian program, and USAF could buy anywhere from 100 to as many as 150 helicopters.
A handful of aircraft would be procured for the U.S. presidential mission, but the high-visibility mission makes it an important win for any contender. In addition, Sikorsky sees the potential for sales in Latin America, Asia and the Middle East, and predicts there could be a need for as many as 300-400 H-92s over the next 20 years. Technologies being offered on the H-92 include:
*A manual and, probably, a power rotor fold system.
*Folding tail rotor.
*A fly-by-wire system developed by BAE Systems.
*A Rockwell Collins mission avionics suite.
*Self-sealing fuel tanks.
*Infrared suppression.
*Protected components to enhance ballistic tolerance.
Company officials note, however, that not every H-92 will have all these features, nor will all Superhawks be fitted with GE's enhanced -8C engines. "We'll customize the aircraft to meet the customer's requirements," Martin said.
With these enhancements, and the upgraded CT7-8C engines, Sikorsky says the twin-engine H-92 will be able to lift more and fly faster than its three-engine competitor. The company also claims that the Superhawk's maintenance costs will be about a third lower than those of its chief rival.
Sikorsky plans to manufacture civil S-92s and military H-92s on separate lines in the company's Bridgeport, Conn., manufacturing facility. And while the first S-92 delivery will be made early next year, the first H-92 with all its proposed features, including the upgraded GE engines, will not be flying until 2007.
According to Ed Birtwell, General Electric's general manager for turboshaft engines, the CT7-8C will be capable of developing about 3,000 hp.--almost 500 hp. more than the 2,520 hp. generated by the CT7-8A. To achieve that, the improved powerplant will incorporate a three-stage power turbine (compared with the -8A's two-stage unit), advanced hot-section materials, minor cooling modifications and upgraded software in the engine's full authority digital engine control.
Despite the lengthened power turbine, the upgraded engines will fit into the same nacelle spaces now available in the S-92 for the CT7-8A, and weight changes prompted by the improvements will be very small.
GE is targeting mid-2007 for FAA certification of the new engine, which fits Sikorsky's schedule for the H-92, Birtwell said. However, he also noted that GE could accelerate the program, "if necessary."
CT7-8C power turbine tests are scheduled to begin near the end of the year, with the new unit fitted into a CT78A. GE chose this approach because "our number one job with the engine is performance," Birtwell said.
GE is discussing the -8C program with potential partners, and decisions regarding participation in the project could be made "in the next several months."
In addition to offering the upgraded CT7-8C in the H-92 Superhawk, the engine has the potential to power Black Hawk helicopters if the aircraft's drive train were replaced with the system used in the S-92. U.S. Army plans, however, call for developing an advanced-technology powerplant for this mission, under the Improved Turbine Engine Program. GE and Pratt & Whitney are teamed for the ITEP effort.