2 february 2009
UNITED STATES - Sikorsky is preparing to take the next step in its X2 Technology high-speed helicopter program, having tested the coaxial-rotor demonstrator for the first time with the tail-mounted pusher propeller turning.
Ground tests of the propulsor are a precursor to high-speed flight tests that will see the helicopter's cruise speed pushed out to an expected 250 knots over three phases. Helicopters typically cruise at around 150 knots.
The X2 first flew in August, and completed an initial three-flight, low-speed test phase to assess basic handling qualities and controllability and to check out aircraft systems. Ground tests of the pusher prop completed the first phase.
Although initial flights of the fly-by-wire helicopter were made without a stability augmentation system (SAS), handling was good, says chief engineering Steve Weiner. The SAS will be added before high-speed testing begins.
The variable-pitch prop is driven from the main gearbox and, in a production aircraft, will be programmed to produce an increasing amount of thrust as the helicopter's speed increases, offloading the coaxial contra-rotating main rotors.
Ground tests checked out the electrically signaled hydraulic actuator that is used to control propeller pitch via the fly-by-wire system. Preliminary data show the propulsion system met pre-test predictions, according to Weiner.
Over the next couple of months, he says, the X2 will be fitted with drag-reducing rotor hub fairings and gear-retraction mechanism. These and other various airframe improvements will reduce drag at high speed.
The speed envelope will be opened in three phases: from 40 to 120 knots using the main rotors for thrust; 120-180 knots using rotor and propeller for thrust; and 180 knots to maximum speed, where the rotor will be producing only lift.
UNITED STATES - Sikorsky is preparing to take the next step in its X2 Technology high-speed helicopter program, having tested the coaxial-rotor demonstrator for the first time with the tail-mounted pusher propeller turning.
Ground tests of the propulsor are a precursor to high-speed flight tests that will see the helicopter's cruise speed pushed out to an expected 250 knots over three phases. Helicopters typically cruise at around 150 knots.
The X2 first flew in August, and completed an initial three-flight, low-speed test phase to assess basic handling qualities and controllability and to check out aircraft systems. Ground tests of the pusher prop completed the first phase.
Although initial flights of the fly-by-wire helicopter were made without a stability augmentation system (SAS), handling was good, says chief engineering Steve Weiner. The SAS will be added before high-speed testing begins.
The variable-pitch prop is driven from the main gearbox and, in a production aircraft, will be programmed to produce an increasing amount of thrust as the helicopter's speed increases, offloading the coaxial contra-rotating main rotors.
Ground tests checked out the electrically signaled hydraulic actuator that is used to control propeller pitch via the fly-by-wire system. Preliminary data show the propulsion system met pre-test predictions, according to Weiner.
Over the next couple of months, he says, the X2 will be fitted with drag-reducing rotor hub fairings and gear-retraction mechanism. These and other various airframe improvements will reduce drag at high speed.
The speed envelope will be opened in three phases: from 40 to 120 knots using the main rotors for thrust; 120-180 knots using rotor and propeller for thrust; and 180 knots to maximum speed, where the rotor will be producing only lift.
..(his wife too
)
