The Eurocopter X3 has set an unofficial helicopter world speed record of 255 knots in level flight, slightly faster than the 250-knot top speed achieved by the Sikorsky X2 compound helicopter in 2010. Eurocopter said the hybrid X3 also reached a speed of 263 knots in a shallow dive, three knots faster than the X2 managed. Once the flight results are confirmed, the X3 would be named the fastest helicopter ever.
Eurocopter hit the historic speed milestones on June 7 at an altitude of around 10,000 feet over southern France near Istres. The X3 is able to achieve such remarkable speed by the use of a slowed main rotor and two forward-facing propellers that together overcome the physical challenge of retreating rotor blade stall common to all helicopters. The fastest traditional helicopters are typically limited to top speeds of around 175 knots.
“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.”
The X3 uses a pair of RTM 322 turboshaft engines to power a five-blade main rotor system with two propellers installed on short-span fixed wings. The concept is well suited for missions requiring long transit flights at high speeds, while retaining full vertical lift and hover capabilities — all at an affordable cost, the manufacturer claims.
Eurocopter envisions a wide range of potential applications for its hybrid configuration, including in long-distance search and rescue (SAR) operations, coast guard missions, border patrol flights, passenger transport and off-shore airlift, along with inter-city shuttle services. Sikorsky, meanwhile, is focused on developing a military version of the X2 known as the S-97 Raider.
With the latest flight milestones, the X3 demonstrator has accumulated a combined total of more than 140 hours aloft since making its maiden flight in September 2010. Last summer, Eurocopter on a U.S. demonstration tour with the X3 for civil operators, military services and law enforcement agencies, with over 55 hours logged and 47 guest pilots taking the controls during appearances from Texas to Virginia.
For more on the X3 and X2 projects, see our feature article “Future Copter” from the September 2012 issue.
