More ground tests before X2 can fly

 - September 24, 2008, 6:13 AM

Sikorsky has nearly finished building its X2 coaxial compound helicopter demonstrator in Elmira, N.Y. According to Jim Kagdis, Sikorsky’s manager of advanced programs, additional ground tests are needed, but first flight is “within arm’s reach.” He declined to provide a specific time period.

As of mid-July, the X2, minus its pusher propeller, had performed 15 hours of ground tests. Part of this time was with the rotor blades on. Another 35 hours will be required before the single-pilot rotorcraft takes to the air. Ground tests take place at test facilities of Schweizer Aircraft, which Sikorsky owns.

The principle behind the X2’s design is for the pusher prop to provide forward thrust, thereby reducing main rotor blade loading and taking max cruise speed beyond the 160 knots typically achievable by more traditional helicopters.

The first of four flight-test phases will take place in Elmira and cover the zero- to 40-knot speed range. Two or three Sikorsky test pilots, including chief pilot Kevin Bredenbeck, will be involved. “We’ll look at the X2 as an integrated aircraft and we’ll look at all subsystems, including the fly-by-wire controls and the engine,” Kagdis told AIN. A single 1,430-shp LHTEC T800 turboshaft powers the X2.

The remaining three test phases will take place at Sikorsky’s flight-test center in West Palm Beach, Fla. They will cover the 40- to 120-knot range, 120- to 180-knot range and 180- to 250-knot range, respectively. The effort will be spread over “the next several years,” Kagdis said.

The focus is on reaching the 250-knot cruise speed with low pilot workload, low noise and low vibration.

He insisted the X2 is a “unique test article” and no production of the design is planned. Rather, this technology “can be applied to a wide variety of designs, up and down the weight scale,” Kagdis said. However, Sikorsky wants to wait for full analysis of test results and market research before deciding on the next step.

In the civil sector, EMS operators could benefit from the rotorcraft’s speed, which could help the patient receive treatment within the golden hour. In the offshore oil segment, the helicopter’s speed could increase productivity, allowing operators to make four or five runs a day to offshore rigs instead of the three they currently make.