Helicopters of the future are likely to feature a pair of contra-rotating rotors and a rear pusher propeller, a configuration which makes them faster than conventional helicopters, just as manoeuvrable and easier to fly.

Helicopters of this new design are fast maturing and are likely to start entering service with the US military around the time Australia starts looking to replace its Tiger Armed Reconnaissance Helicopters.

Sikorsky director of business development for Future Vertical Lift Richard Koucheravy said the US had reached the conclusion that for future combat, helicopters would need longer range and higher speed while maintaining lethality.

For Future Vertical Lift Sikorsky is jointly developing the Defiant with Boeing, using its experience with its Raider and X-2 demonstrators.

The Raider uses a compound coaxial lift offset rotor with a pusher prop. It first flew in 2015 and has achieved maximum forward airspeed of 185 knots with some manoeuvring.

“We believe the end state will be a helicopter that flies above 220 knots and is fully manoeuvrable,” Mr Koucheravy said at LAND FORCES on Wednesday.

The earlier X-2 concept demonstrator aircraft achieved 250 knots.

The US Army has issued a draft offer for its ambitious Future Vertical Lift program with design awards mid next year and prototypes flying in 2023-24 and production from 2028.

“Essentially what the X2 technology allows in forward flight is two rotor systems providing lift on both sides of the aircraft. If you only have one (rotor), the retreating blade stops producing lift at high speeds,” he said.

“This retains the very best hover and low speed performance of a helicopter yet allows you to fly at near airplane speeds.”

Helicopters with contra-rotating rotors aren’t new. The Russian firm Kamov makes a number of helicopters in this configuration, of which perhaps the best known is the Ka-50 attack helicopter.

These machines feature flexible rotor blades which means the two rotors need to be widely spaced. Raider uses rigid blades which means the rotors can be placed closer together.

Flight controls are fully fly-by-wire, making pilot operation far easier than with traditional controls.     

Lockheed Martin director of business development for Australia and New Zealand Neale Prescott said this new technology was especially important for Australia.

“At the time that Australia is going to be making choices around the Defence Integrated Investment Plan, the Special Forces light helo, potential replacement of the Armed Reconnaissance Helicopter, the Future Vertical Lift program will be absolutely relevant,” he said.

“Later on in the decade the Australian battlefield lift helos will be examined to determine do they proceed on or do they look at an alternative.

“This is the next technology in rotor craft. It brings a lot of opportunity for the Australian Defence Force in terms of speed and endurance and the tactical advantage,” Mr Prescott said.