Sikorsky president Jeff Pino says the company has cleared the X2 technology demonstrator flight team to proceed with flight tests that are likely to see the counter-rotating coaxial rotor pusher exceed 200kt (370km/h) airspeed and beyond in the very near future.
Pino told Flight Daily News that X2 test pilot Kevin Bredenbeck had requested additional pitch stability at the conclusion of phase three of the programme, which culminated in an 181kt speed during aircraft's twelfth test flight on 25 May.
During that flight, engineers also successfully tested slowing the X2's main rotors by 5% to prevent tip speeds from approaching Mach 1, a key process for pushing speeds higher.
For added pitch stability, Pino says engineers increased the vertical stabiliser area by about 0.46m2 (5ft2). "We flew another flight to validate that work," says Pino. "Now we're cleared to go over 200kt." The company earlier added 0.28m2 of area to each of the outboard vertical end plates for additional yaw stability.
Pino says a key goal for the project, reaching a cruise speed of 250kt, is within "three or four flights" once the X2 returns to flight, likely in the "next few weeks" as the final phase of flight-testing begins.
Pino says the company is happy with the noise signature of LHTEC T800-powered fly-by-wire pusher as well, comparing the sound to that of a Eurocopter EC135. "When we showed it, our customers said, 'Wow, that is pretty quiet,' says Pino. "We won't say what customers."
Aside from offering the concept as candidate for the US Army's armed aerial scout programme, an idea Pino says is "still a bit of a long putt for the X2 demonstrator", Pino says Sikorsky is not "trying to place" the aircraft. Of the commercial market, he says "it takes a lot of gas" to go that fast. "We've got to do a lot more evaluation," says Pino.
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Source: Flight Daily News