Sikorsky expects 265kt from X2

Washington DC
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Sikorsky engineers say the company's self-funded X2 advanced technology helicopter could reach 265kt (490km/h) or more in the next few months after a central sail fairing is installed on the rotor mast.

The twin coaxial contra-rotating rotor demonstrator reached its project goal speed of 250kt in level flight during a morning test flight on 15 September in West Palm Beach, Florida.

At that speed, test pilot Kevin Bredenbeck says the T800-powered pusher had a reserve of around 300hp (225kW), although test limits held the speed to 250kt, a programme target speed achieved about midway through the 1.1h flight. Total power required to maintain 250kt was 1,300hp, 80% of the T800's capability.

 © Sikorsky
The Sikorsky X2 twin coaxial contra-rotating rotor demonstrator reached its project goal speed of 250kt in level flight during a test flight on 15 September

In slightly over two years of testing, the X2 has flown for 16.2h on 17 flights, far exceeding the maximum level cruise speed for a helicopter to date - officially 217kt by a Westland Lynx, and unofficially 236kt by the company's XH-59A demonstrator in the early 1970s.

Sikorsky is investigating whether to attempt an official speed record during the final flight-testing on the vehicle, which is likely to involve two flights for acoustic testing and two flights for sail fairing and higher speed testing.

Steve Weiner, chief engineer for the X2 programme, says the stationary sail fairing, sandwiched between the two main rotors, could add 15kt to the cruise speed, once engineers perfect the installation.

Ground tests of the fairing are to start in the next few weeks.

Weiner says Sikorsky is investigating whether to attempt an official speed record during the remaining testing on the vehicle, which is likely to involve two flights for acoustic testing and two flights for sail fairing and higher speed testing.