The development of the Heli-plane has been in progress for over five decades. Many helicopter companies around the world have seriously pursued this goal of designing an aircraft that can effectively accomplish two separate functions, first; being capable of flying in a continuous stable hover, and second; being capable of flying at a reasonable cruising speed.
The following is a brief description of some of the more significant attempts from the helicopter industry to produce a feasible aircraft that can hover and fly fast. These highlights include; tilt rotor aircraft, heli-planes, gyrodyne aircraft, high-speed helicopters and future design concepts that other companies in the rotorcraft industry are presenting.
Tilt Rotor
http://avia.russian.ee/helicopters_eng/canadair_dynavert-r.html
http://avia.russian.ee/helicopters_eng/tiltrotor.html
The Canadair CL-84 had demonstrated a successful stable hover and transition to forward cruise flight in January 1966. This general concept of a tilt rotor has been attempted by many different companies and is still seriously being pursued. Some of the technological challenges that Tilt Rotor designs face ; minimal agility in the hover mode, and more critically, the inability to auto rotate or demonstrate an emergency power off landing.
Heli-Plane
http://avia.russian.ee/helicopters_eng/ka-22.php
http://avia.russian.ee/helicopters_eng/lok_cheyenne.php
http://avia.russian.ee/helicopters_eng/sik_s-67.php
http://avia.russian.ee/helicopters_eng/sik_x-wing.php
http://www.cartercopters.com/
 Heli-plane development through the years has typically been; the use of a rotor system for the hover, and then a transition into the fixed wing configuration for cruise . The rotor system is unloaded to some degree, or completely in the cruise mode. The Challis Heli-Plane is the first design to present ; a balanced relationship between the lift of a rotating wing and the lift from just one fixed wing in the cruise mode.
The Challis Heli-Plane is also the first design to present an oversize horizontal stabilizer that is extended at the rear of the aircraft and angled downward . This is in effect a wing that is lifting the rear portion of the aircraft in the cruise. The implementation of an empennage that is lifting in cruise flight, is completely different than all other aircraft.
Gyro Dyne
http://avia.russian.ee/helicopters_eng/fairey_rotodyne.php
http://www.groenbros.com/
The Gyrodyne uses compressed air to drive the tips of the main rotor when in the hover mode. This method of applying power from the engine to the rotor blades, via an air compressor and then through the rotor blade to the tips, is intended to relieve the dependency of a tail rotor that counter acts torque like on a conventional helicopter. This, however, is a complicated technique and the aircraft has limited yaw axis authority.
High Speed Helicopter
http://www.sikorsky.com/details/0,9602,CLI1_DIV69_ETI2365,00.html
This contra rotating concept presents, in a high speed cruise condition, that there will be a balanced relationship between the lift of an advancing rotor blade on the lower rotor system to equal the lift of the advancing blade on the upper rotor system. This Sikorsky system is certainly more complex, would have more drag, and would be more expensive to build and maintain than a Challis Heli-Plane.
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