1.    A pair of intermesh counter rotation tandem twin rotors on top to produce vertical lift.

2.    The tandem twin rotors can be off power and perform free counter autorotation.

3.    A unique variable and reversible pitch pusher Prop-rotor installed at straight back.

4.    At static hover mode, the pusher Prop-rotor is at idle speed RPM, and feathering 0 pitch.

5.    At forward flight mode, the pusher Prop-rotor performs variable RPM, and variable pitch; The tandem twin rotors will reduce engine power and collective pitch,  but no enter to forward cyclic pitch ( except yaw and rolling control )

6.    At cruise speed forward flight mode, the tandem twin rotors spin at semi threshold gyro wind mill autorotation. Only 50% engine power is need to maintain the autorotation. Another 50% engine power is applied to the pusher Prop-rotor, to produce the maximum forward velocity energy and create wind milling force feed back to the top twin rotors. Thus, semi active power and semi auto rotation drive the twin rotors producing lift.

7.    The compound Heli-Linn Copter has a distinctive character that its lift is always more than its weight !

8.  The compound Heli-Linn Copter has  a fuselage shape a little bit like the CH-47 Chinook, but significant different characters from the CH-47.