On Sept.15, 2010, Sikorsky Aircraft’s X2 Technology demonstrator flew at a speed of 250 knots true airspeed in level flight at the Sikorsky Development Flight Center in West Palm Beach, Fla. Reaching 250 knots accomplished the program’s ultimate speed target. The milestone, reached during a 1.1-hour flight, is an unofficial speed record for a helicopter. The demonstrator also reached 260 knots in a very shallow (2-3 degree) dive during the flight. (To make the record “official,” the National Aeronautic Association (NAA) must be on site to record the flight and verify the speed with its own equipment. Sikorsky would need to invite the NAA to West Palm Beach for a future flight. A spokesperson for the company said it has not been decided when or if they will do this).
|Sikorsky’s X2 team during pre-flight briefing prior to attempting to reach 250 KTAS. In foreground is Bob Blackwell, one of the engineers on the team.|
“I think it’s a great day for our industry. Today Sikorsky successfully completed all its key parameters involved with its X2 Technology demonstrator. Those [parameters] being the demonstration of active vibration control, that being fly-by-wire aircraft and most importantly, and I think most visibly, the fact that today we achieved 250 knots true airspeed in level flight. It’s been an exciting couple of years and I’m just pleased to be able to announce to our community that this has finally, finally happened,” Pino told Rotor & Wing during an interview shortly after the flight. (Visit www.rotorandwing.com for the full interview.) “Our primary key performance parameter has been met,” said Jim Kagdis, program manager for Sikorsky Advanced Programs. “The 250-knot milestone was established as the goal of the demonstrator from its inception.”
Pino went on the say that he had hoped to see it happen a little quicker. “But one of the things we told our team was that the priority here is safety. No technology that isn’t safe has any value to our customers or our shareholders,” he said. “But if you think about it, while it was four and a half years, we did this in 17 flights; less than 16-and-a-half hours. We went from lifting it from a hover to truly mechanizing an incredibly complex piece of technology to 250 knots true airspeed. It’s been fun. It’s been a really great journey for us,” he added.
|Key X2 team member Dave Walsh checks out the rotorhead prior to Flight 17 at the Sikorsky Development Flight Center in West Palm Beach, Fla.|
While the buzz revolved around the speed, Pino said some of the other technologies that were proven were equally important. He pointed to the drag reductions, the rigid rotor blades that keep the two rotor systems closer together, the coaxial integrated pusher prop and its interaction with the main rotor and the fly-by-wire technology. He also stressed that one reason the X2 was able to go from 235 to 250 was the fact that the automatic vibration control was able to “literally and figuratively on the fly” adjust from a vertical vibration to help fix a lateral vibration.
Kevin Bredenbeck, Sikorsky’s director of flight operations and chief pilot for the company and its X2 Technology program, was at the controls for the milestone flight. Bredenbeck said the demonstrator has been performing well, meeting expectations of performance predictions and progressing with every test flight. “It was quite responsive. We’ve only had it up to a 30-degree bank angle but [you can tell] this aircraft has lot of potential [maneuverability],” he said. “And this is not a Sikorsky guy talking for Sikorsky. This is a pilot being a pilo t. The control power is amazing.”
When asked if he believed that achieving the record will lead to a paradigm shift for the future of helicopter design and operation, Pino hedged. “That’s a big, big question. I don’t know that. I don’t know if I want to make this any bigger than we set some goals, we proved some technology, our processes improved and we’ll go back and put our heads around what we do next.”
|Chief Pilot Bredenbeck prepares to take the X2 through its paces. “This was truly a collaborative effort that demanded a tremendous sacrifice from the full team,” he said later.|
As for the future, Pino said the demonstrator had three to five more flights in it. He said they met the key speed performance parameter without a final aerodynamic drag reducing treatment that they would install and test on one of the coming flights to “see if there is any more there.” The team also wants to gather some more data with the pusher prop running and not running for acoustic data. “I want to show this to some customers and some of our corporate stakeholders because videos don’t do this justice. It’s when you watch it actually out accelerate a very quick S-76 in half a runway that you start to understand there could be some real opportunity here,” Pino said. (From October 2010 Rotorcraft Report)