As expected, at no time during our hovering exercise did the power limit get close to 100%. The aircraft automatically computes its own weight and at 9,494 lb., a stable hover required 62% torque. The aircraft is limited to 35 kt. sideward and rearward flight, which required only 79-80% torque for each. There was no problem with tail-rotor authority with the tail stuck into the wind as the wind was minimal. There was a slight increase in vibration, but that was all.
I found the aircraft to be a bit tight on the controls during standard hover maneuvers, and Barnes recommended using the force-trim release buttons to loosen it up. That helped a lot—although it then seemed a bit too sensitive. But, like pilots, every helicopter has its idiosyncrasies. You get used to them, and it did not take long to figure out how to handle this one.
By engaging the autopilot's velocity hold (VHLD) function, hovering can be accomplished by simply “beeping” the aircraft to where you want it. Placing a green circle at a point on the runway map display—with zero airspeed dialed in—puts the aircraft in a stable, hands-off hover. Repositioning the green circle repositions the aircraft. Changing the heading while maintaining zero airspeed turns the nose of the aircraft without changing its position. If the helicopter is at a stable hover and the wind blows it off its hold point, it will recalculate and return to the original position.
Takeoffs, both normal and maximum performance, were without drama. Climb out for a normal takeoff was at 75 kt., 750 ft./min. at 59% torque. The aircraft monitors outside air temperature and weight to determine best rate of climb, for both normal and one-engine-inoperative climb outs, and indicates that rate with a white triangle on the airspeed indicator.
We climbed to 2,000 ft. holding 100 kt. in the climb, then accelerated to 130 kt. and engaged vertical and area navigation to hold us on a steady course and altitude. An assortment of charts is available to the pilot on the digital map display. Barnes pulled up a vector chart to demonstrate the aircraft's flightpath control. He simulated a large storm cell directly ahead, then used the cursor control to mark a point to the right of the storm. The aircraft automatically turned toward that mark. Remarking our original aimpoint, Barnes said when the aircraft reached the new waypoint, it would automatically track to the original point, thereby avoiding the storm. This was all done by using the trackball and pushing a single button.
The Thales system offers XM Weather for on-screen satellite weather service as an option. Also available as an option are automatic dependent surveillance-broadcast (ADS-B) and GPS precision-approach capabilities. The baseline weather radar for the D model is the Honeywell Primus 660.
To test its basic flight characteristics, we took the aircraft up to its 155-kt. never-exceed speed (Vne), pulling only 50% torque. Barnes notes that, while Vne is 155 kt., because of the efficiency of the Pratt & Whitney Canada engines, cruise speed for best range is 154 kt. He also notes that Sikorsky already has the data to increase the Vne limit “down the road.”
For steep turns, Barnes “beeped” the aircraft over into a 30-deg. angle of bank and put it on automatic hold. The aircraft held steady at 110 kt. pulling only 40% torque. The 30-deg. bank angle is the maximum for automatic hold. That can be manually overridden to allow up to a 60-deg. bank, at which point a warning voice announces that you are reaching power limits.
Virtually all aspects of the flight can be performed using the push-button controls on the autopilot control panel (ACP) located directly behind the trackball housing on the center console. Barnes programmed in a flight plan for the approach back to Sikorsky's field, then coupled in the heading, airspeed and altitude using the pushbuttons on the ACP.
The aircraft flew itself to the ILS, then automatically transitioned to ILS mode. The navigation, glideslope and deceleration commands are coupled to the primary commands in the autopilot, allowing the aircraft to fly hands-off down to the runway.