The fastest helicopter in the world is the Eurocopter X3. The X3 can fly at speeds of up to 302 miles per hour.
Unveiled in 2010, the Eurocopter X3 is a high-speed compound helicopter made by Airbus Helicopters. It was built using a propeller on each of its short span wings. Each propeller has a different pitch which helps it counter the torque effect of its main rotor. The design helps it to reach unheard of speeds for a helicopter.
The X3 first took to the skies in September, 2010 and its speed was first clocked in 2011. At that time, it flew at speeds of up to 267 miles per hour using only 80 percent of its available power.
Over the next 2 years, the X3 performed several other test flights around the world, and in June, 2013 it beat the unofficial record achieved by the Sikorsky X2 in 2010. During that flight, the X3 hit sustained speeds of 293 miles per hour and the speed of 302 occurred when the helicopter went into a shallow dive. For these speeds, the X3 is now considered the world's fastest non-jet augmented helicopter.
The X3 holds two crew members, weighs 11,464 pounds, and has a five-bladed main rotor along with a main rotor area of 1,342 square feet.