Aircraft Number 3, the closest representative to Sikorsky's production-model S-92 helicopter, has joined Aircraft 2 in developmental flight testing. This latest developmental aircraft features the S-92 production model's engine, the GE-CT7-8, and all associated digital engine controls. Flight testing will be primarily focused on powerplants and automatic flight-control systems validation. Five aircraft will be active in the flight development program from now until certification, which is scheduled for 2001.
During its first flight, which lasted about 1.3 h, the aircraft performed maneuvers such as hover, paced yardwork (60 kt forward and 35 kt left and right), level flight to 120 kt, maximum continuous power climb, and partial power descent. The ground test vehicle, Aircraft 1, recently completed a 200-h endurance run to certify the entire drive system including main, intermediate, and tail gearboxes.
Flights have also been conducted at maximum gross weights with various cg locations, from full forward to full aft, at a wide range of airspeeds. Tethered hover flight, both in and out of ground effect, was recently completed recording 31,000 lb of lift generated, confirming projected performance. Flights continue with current emphasis focusing primarily on the handling qualities of the aircraft at various operating weights.
Early assessment of the program objectives has confirmed design predictions, according to the company. The active vibration system has been functional since the first flight. Performance and range predictions have been validated. Acoustic levels are below certification requirements. Reliability has been better than predicted at this point in the test program, with an estimated direct maintenance cost of $800/hr.
Aircraft 4 is scheduled for completion this year, incorporating a final update to the avionics configuration and ensuring that the latest available equipment is included for certification. Aircraft 5, the utility-configured aircraft, will join the flight development program sometime this year. At time of press, the aircraft was in Stratford, CT, undergoing final assembly and instrumentation installation.
The Sikorsky S-92 is the company's newest medium helicopter of which deliveries begin in 2002. The aircraft is based on proven U.S. Army Black Hawk and U.S. Navy Seahawk helicopters, which have logged more than 4 million flying hours. The S-92 has a metal and composite airframe and a highly integrated flight avionics package. Powered by twin General Electric CT7-8 turboshaft engines, it has a range of 400 nmi with fuel reserves, a cruising speed of 155 kt, and a 15,000 ft service ceiling.
Frank Bokulich
