Most helicopters are built for hovering, not for speed. But the Eurocopter X3 is built for both. The demonstrator tilt-rotor aircraft proved as much when it set a pair of air speed records earlier this month.
Based on the Eurocopter EC155, the X3 is a hybrid helicopter. That is, in addition to its five blade main and tail rotors, the X3 is also outfitted with a pair of stubby wings (similar to those aboard the Mi-24 HIND but with propellers instead of missile pods) that provide up to 80 percent of the aircraft's lift. A pair of 2270 HP Rolls-Royce Turbomeca RTM322 turboshaft engines drive all four rotors and allow for a 12,500 foot service ceiling and blindingly fast speed.
On June 7th, the X3 blew through the previous air speed record for helicopters by cruising at 255 knots (293 MPH) during a 40-minute flight over Southern France near Istres. This acheivement followed the X3 topping 263 knots (302 MPH) during a descent just days before. “It’s no exaggeration to say that the X3 is clearly in its element at high speeds.” said Eurocopter test pilot Hervé Jammayrac. “While flying at both 255 knots and 263 knots, the X3 performed exactly as it has throughout its flight envelope, exhibiting outstanding stability and providing a low vibration level without any anti-vibration system.”
Since its maiden flight in 2010, the X3 has ammassed over 140 hours of air time. And though this particular demonstrator will likely be retired at the year's end, the X3's turboprop technology is slowly making its way into production. “Helicopters can fly relatively fast and the noise footprint for people living around the airport is relatively similar to current traffic noise, so vertical lift can still play a role in commuting people, providing you can design an aircraft that delivers higher speed at reasonable cost,” said former Eurocopter CEO Lutz Bertling. “I believe we could well see the first serial products which could do the job with a smaller number of passengers—say 19 seats—at the beginning of the 2020s, and I could imagine seeing larger aircraft with 30-40 seats in the mid-'20s.”
While these hybrid aircraft are significantly faster than conventional helicopters, the X3 cannot keep up with turboprop planes—yet. But for a helicopter, its speed is utterly amazing. [Gizmag - Eurocopter - Aviation Week - Wikipedia]