Feeds

X2 triplex supercopter gets tail-drive hooked up

3 eggbeaters = 1 worldbeater?

Beginner's guide to SSL certificates

US helicopter firm Sikorsky has announced successful ground testing of its "X2" twin-rotor, tail-prop high speed helicopter prototype with the tail propulsor fitted and working. The firm says the X2 is on track to achieve 250-knot speeds this year - beating normal helicopters by two thirds again.

Sikorsky art of the X2 demonstrator

Faster than a good hoverer: hovers better than anything fast. On the drawing board, anyway.

"The high-speed pusher prop produced the expected amount of thrust and the testing went according to plan," said X2 chief Steven Cizewski. "In addition, the pusher prop's drive system and oil distribution system checked out well. In all, we are pleased with this milestone and look forward to finishing the tests."

The X2 has already made its first flight, but that was without any use of the tail propellor - which will be necessary for the new machine to achieve its full potential. The idea of the X2 design is to achieve much faster cruising speed than a normal helicopter can manage, while retaining good performance in the hover and - according to Sikorsky - avoiding the complexity and high maintenance burden attendant on tiltrotor designs auch as the V-22 Osprey and BA609.

The normal problems suffered by helicopters attempting to beat 150 knots or so are avoided by the X2's design. The issue of "retreating blade stall" - where the backward-spinning blade briefly becomes almost stationary in the air owing to the speed of the aircraft, so losing lift - isn't a problem as there are forwardgoing blades on both sides at any moment. The problem of the forward-moving blade tips going supersonic is sidestepped by the use of variable speed rotors: most helicopters spin their blades at a steady rate, but the X2 can slow them down as speed increases, keeping the tips safely subsonic.

All this, Sikorsky engineers believe, will allow the tail prop to safely push the triplex copter up to cruise at 250 knots: beating the Osprey, and potentially doing so in an aircraft which would also work better in the hover than the controversial US military tiltrotor. (The Osprey's blades, in order to offer decent performance as propellors in the cruise, are necessarily shorter than one would choose to have them for use as vertical-lift rotors. No such constraint applies to the X2.)

Previous efforts along X2 lines have been bedevilled by vibration issues and excessive weight, but Sikorsky believes that modern superstiff rotors, variable rotor speed and active vibration damping tech will squelch the shudder. Use of a pusher prop driven by the main engine, rather than extra strap-on jet engines as with the ill-fated XH-59A demonstrator, is expected to offer a much lighter design. Sikorsky also like to emphasise that smaller X2 craft of the future could be single engined, something which is definitely not an option for tiltrotors.

So great is the firm's faith in its technology, indeed, that it is proceeding with development at its own expense rather than the more normal route of expecting funds by one or another channel from the US taxpayer. ®

Secure remote control for conventional and virtual desktops

More from The Register

next story
MEN: For pity's sake SLEEP with LOTS of WOMEN - and avoid Prostate Cancer
And, um, don't sleep with other men. If that's what worries you
Voyager 1 now EIGHTEEN LIGHT HOURS from home
Almost 20 BEEELION kilometres from Sol
HUGE SHARK as big as a WWII SUBMARINE died out, allowing whales to exist
Who'd win a fight: Megalodon or a German battleship?
Jim Beam me up, Scotty! WHISKY from SPAAACE returns to Earth
They're insured for $1m, before you thirsty folks make plans
ROGUE SAIL BOAT blocks SPACE STATION PODULE blastoff
Er, we think our ISS launch beats your fishing expedition
Comet Siding Spring revealed as flying molehill
Hiding from this space pimple isn't going to do humanity's reputation any good
BAE points electromagnetic projectile at US Army
Railguns for 'Future fighting vehicle'
LONG ARM of the SAUR: Brachially gifted dino bone conundrum solved
Deinocheirus mirificus was a bit of a knuckle dragger
prev story

Whitepapers

Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.
Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Saudi Petroleum chooses Tegile storage solution
A storage solution that addresses company growth and performance for business-critical applications of caseware archive and search along with other key operational systems.
Getting ahead of the compliance curve
Learn about new services that make it easy to discover and manage certificates across the enterprise and how to get ahead of the compliance curve.