Sikorsky earlier this year took a series of "glamour" shots of the engineering team for its X2 advancing blade concept pusher helicopter. With the help of dark shades, techy helicopter backdrop and slick threads, the engineers did in fact look like cool dudes.
Looks can be deceiving however, and in the case of the X2, that's a good thing.
In a world where immediacy and appearance have become paramount, there are still those who go to work in a cubicle every day and perform a seemingly astonishing feat called thinking. Call the engineers nerds if you like, but you have to like what they do.
In the case of the X2, the engineers were given extra years to think. X2 was "supposed" to fly in 2006 but didn't until 2008. But Sikorsky was in no rush, convinced the future of rotorcraft is to blend the a helicopter's vertical lift with the speed of a fixed-wing aircraft.
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© SikorskyThe future's so bright... |
Like a fine wine, such a vehicle could not be served before its time. Sikorsky had tried in the 1970s with its XH-59A, an advancing blade concept design that was fast but impractical before advances like active vibration control systems.
The Bell Boeing tiltrotor approach can dash at 270kt (500km/h), but Sikorsky believes configuration changes like swivelling the engines to change the lift vector are not the way to go. But while the advancing blade concept's counter-rotating coaxial main rotors overcome the retreating blade stall barrier to rotorcraft speed, the problem remains that in acceleration past 180kt to the X2's planned 250kt cruise speed, the blade tips would go supersonic and thus need to be slowed - no mean feat.
These quandaries took thinking time to solve. Air shows came and went with Sikorsky chief Jeff Pino telling an impatient press that the X2 "will fly when we're ready for it to fly".
The engineers were ready in 2008 for a maiden flight, part of a methodically thought-out four-phase flight test plan - with no hard dates attached.
Last week test pilot Kevin Bredenbeck finished phase three of the flight-test programme, hitting a speed of 181kt in cruise, beyond what's possible for most traditional helicopters. The engineers' automated algorithms successfully slowed the main rotors for the first time, making phase four and its ultimate end goal of 250kt a very realisable goal.
When will it happen? When the thinkers at Sikorsky - the engineers - are ready for it to happen. It will be worth the wait...
Source: Flight International
