Eurocopter yesterday unveiled the X3 (“x cube”) demonstrator, a compound helicopter with a 220-knot cruise speed. The aircraft first flew on September 6 in hover, and is scheduled to fly again on Thursday. Some 100 flight-test hours are planned in the next 18 months, with the target speed expected to be reached in the first quarter. The demonstrator uses a Dauphin-series fuselage and main rotor, with two short wings fitted to the upper fuselage, each holding an eight-foot-diameter propeller. A conventional empennage replaces the tail rotor. Its two RTM322 engines are borrowed from the NH90 military transport and the main gearbox comes from the EC175, but with two additional drives for the propellers. Eurocopter has been secretly working on the X3 project since early 2008. The company said it is not engaged in a speed race with Sikorsky’s X2, which recently reached 250 knots. Rather, Eurocopter officials believe they have found a sweet spot at 220 knots. On a given mission, time savings are projected to translate into lower hourly costs–about 20 percent lower from the standpoint of cost per passenger mile–which Eurocopter said will compensate for the increased purchase price. A 20-seat, 30,000-pound-class certified variant of the X3 could enter service in about eight years, Eurocopter said.