But to build an even faster helicopter is going to take another huge leap in engineering.
The way conventional helicopters are built makes it almost impossible for them to fly very fast. Their spinning blades slice through the air and work like the wings of a plane, generating lift. Unlike wings, however, the blades don’t provide equal lift on both sides. As a blade on one side moves forward, a blade on the other side is moving backwards. When a helicopter starts to speed up, this difference becomes more serious. Air passing over the blade moving in the same direction as the helicopter travels faster than it does over the opposite blade. It is a problem known as retreating blade stall.
But with radical redesign, helicopters are capable of being speed demons. Sikorsky, a helicopter maker based in Florida, holds the record for the fastest helicopter flight. Its X2 concept flew at over 250 knots (460 km/h) in 2010. The X2 uses two counter-rotating rotors, meaning two rotors stacked on top of each other, spinning in opposite directions. That means there is an equal amount of lift being generated on each side.
Another advantage of the design is that engineers can remove the tail rotor, which is usually needed to stop the helicopter spinning around. That gave them extra room for a propeller at the back.
Steve Weiner, Sikorsky’s Director of Engineering Sciences, and was chief engineer on the X2 programme. “The concept has been around since the late 1960s,” he says. It was originally tested on an aircraft called the XH59A. “That aircraft went pretty fast (238 knots/440 km/h) but it vibrated very badly, it was very noisy and it used a lot of fuel. It also needed two pilots to operate it,” he says. “There were enough controls that they had both hands, both feet, and anything else available operating controls!”
Advances in computing and ‘fly-by-wire’ flight systems have made the craft much easier to fly, and the proof of the design is in the world speed record. The double rotors mean no retreating blade stall, and a much smoother and quieter ride. Now the team is working on a next generation helicopter incorporating the technology.
It will take 15 years or more before we see these ideas in everyday operation, but the people working on them believe they can give us what we, the passengers, demand; safety, efficiency and comfort. “If you’re trying to fly around passengers, they are certainly not going to fly on something that is shaking like crazy and rattling their teeth,” Russell says.
