270 kts. High Speed Helicopter
310 mph - Lower costs - Higher payload
Conventional helicopters reach speeds of 150 kt. (175 mph) because of the loss of lift forces at the retreating rotor blade at higher speeds. Counter-rotating rotors prevent the effects of the losses, but their mechanisms are very complex, heavy and increase the air drag significantly.
The new high-speed helicopter consists of a simplified conventional main rotor, a tiltable tail rotor, and small wings. Both rotors are in vertical position during takeoff, and the tail rotor additionally slightly tilted sidewise for creating the antitorque for the main rotor.
During the transition, the tail rotor tilts continuously into horizontal position, providing increasing thrust for horizontal flight. After reaching the speed of wing-supported flight, the blades of the main rotor are rotated into a position with the blades parallel to each other, and the rotor, drive system and tilt mechanism are folded into the fuselage. The air resistance is minimized and compensated for by the reduced drag of smaller wings and smaller frontal area of the engine.
The helicopter concept is based on the flexibility of the new advanced hydrostatic drivetrain with very high power/weight ratio and efficiency, consisting of a new hydraulic free-piston combustion engine driving the hydraulic motors of both rotors with pressurized fluid.
The 2-stroke free-piston engine with impulse charger and peripheral fuel injection has three cylinders, each with two opposed pistons, controlled by fast electro-hydraulic 2-way valves, determining the speed and compression ratio. The pistons, transferring the combustion energy directly into pressurized fluid without a crank mechanism, are free of side loads allowing for unlubricated operation and very high combustion pressure. The effects of higher temperatures are avoided by using steel components and exposing the exhaust ports only to lower gas temperatures at the end of the stroke. The impulse charger piston is driven by exhaust gas and pumps air into the combustion chamber and fluid into the hydraulic circuit. Very high combustion pressure, low heat losses, recuperation of exhaust energy, and ultra-high pressure peripheral fuel injection reduce the fuel consumption by 30% (0.23 lb/hp•h) and the weight. The engine (1,970 hp, 326 lbs.) consumes 45% and weighs 35% less than turboshaft engine. (2 U.S. Patents, International patents, Patents pending)
The swashplate-type axial-piston motor has 33° infinite variable displacement, medium pressure ports, and off-center adjustment for minimizing the size and the dominating internal fluid and compression losses. The new concept increases the displacement range by 60% and turbine like cylinder ports the flow capacity, reducing size and weight by a factor of 6. The smaller size, lower bearing loads and DLC coatings reduce frictional losses more than 50%. The greater range and lower losses multiply the usable operating range (torque, speed) by a factor of 5. Each motor (1,140 hp) with reduction gear weighs 180 lbs. (2 U.S. Patents, International patents)
Only current materials and methods are applied. The helicopter improves the cost of ownership, payload, travel time and comfort (vibration, noise) significantly.