Sikorsky completes X2 prototype build

 - July 14, 2008, 1:31 AM

Helicopter manufacturer Sikorsky (Hall 4 Stand F14) has nearly finished building its X2 coaxial compound helicopter demonstrator in Elmira, New York. Although additional ground tests are needed there, first flight is “within arm’s reach,” according to Jim Kagdis, Sikorsky’s manager of advanced programs. He would not commit to a specific time period, however. The X2 program is entirely funded by Sikorsky.

The X2, incomplete without its pusher prop, has performed 15 hours of ground tests. Part of that time was spent 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.

In Elmira, the first of four flight test phases will cover the 0-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 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, Florida. They will respectively cover the 40- to 120-knot, 120- to 180-knot and 180- to 250-knot speed ranges. The effort will occur over “the next several years,” Kagdis said, and focus on reaching a 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, the 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 test results and market research analysis before deciding on the next step.

In military applications, Kagdis sees X2 technology suitable from UAVs to 25,000-pound, Black Hawk-sized aircraft. For example, he hinted, a 7,000-pound light twin could take off from a boat. It could quickly ingress an operational area, then use its helicopter maneuvering capabilities and eventually perform a swift egress.

In the civil area, EMS operators could benefit from the rotorcraft’s speed. That could help the patient being treated within the golden hour. In offshore oil, operators could increase productivity. Instead of three, they could make four or five runs a day to offshore rigs, Kagdis asserted.

The principle behind the X2’s design centers on providing forward thrust with the pusher prop, thus reducing main rotor blade load. In turn, it lifts the usual 160-knot-or-so speed limit with which helicopters have to cope.