Tilting duct compound helicopter

Abstract

A rotorcraft that utilizes both a main compound rotor and a plurality of tiltrotors is disclosed. The main rotor and the thrusters can provide vertical lift for vertical take-off and landing of the rotorcraft. The thrusters of the rotorcraft can articulate to a horizontal position to facilitate horizontal flight. The main rotor of the rotorcraft can continue to provide vertical lift for the rotorcraft in horizontal flight, as well as operate in an autorotation mode. In the event of a failure of the main power source of the rotorcraft, the main rotor in autorotation mode can safety land the rotorcraft. In the autorotation mode, the main rotor can create electrical energy that is stored in a battery and can be used to power the plurality of thrusters. The rotorcraft can also be configured in an anti-torque mode, where the thrusters cancel out the torque of the main rotor.

What is claimed is: 
     
         1 . A compound rotorcraft, comprising:
 an airframe structure;   a plurality of thrusters operably coupled to the airframe structure, the thrusters operably rotatable between a vertical lift position and a horizontal cruise position, the thrusters configured to provide vertical thrust in the vertical lift position and horizontal thrust in the horizontal cruise position at a cruise speed; and   a main rotor operably coupled to the airframe structure, the main rotor configured to operate in an autorotation mode when the rotorcraft reaches the cruise speed in horizontal flight,   wherein the main rotor is configured to generate electrical energy driving the thrusters in the autorotation mode.   
     
     
         2 . The rotorcraft of  claim 1 , further comprising a battery configured to store the electrical energy generated by the main rotor assembly. 
     
     
         3 . The rotorcraft of  claim 2 , wherein the electrical energy stored by the battery is configured to power the plurality of thrusters. 
     
     
         4 . The rotorcraft of  claim 1 , wherein the plurality of thrusters are ducted fans. 
     
     
         5 . The rotorcraft of  claim 1 , wherein the main rotor is further configured to generate vertical lift. 
     
     
         6 . The rotorcraft of  claim 1 , wherein the main rotor is further configured to generate vertical lift when operating in the autorotation mode. 
     
     
         7 . The rotorcraft of  claim 1 , further comprising a primary energy source configured to power the plurality of thrusters. 
     
     
         8 . The rotorcraft of  claim 7 , wherein the primary energy source is a battery. 
     
     
         9 . The rotorcraft of  claim 1 , wherein the airframe structure is a fuselage. 
     
     
         10 . The rotorcraft of  claim 1 , wherein the main rotor mechanically disengages a drive system in the autorotation mode. 
     
     
         11 . A method for powering thrusters of a rotorcraft during autorotation, comprising:
 generating electrical energy with a main rotor while the rotorcraft is in horizontal flight;   storing the electrical energy generated by the main rotor; and   driving the thrusters in an autorotation mode with the stored electrical energy.   
     
     
         12 . The method of  claim 11 , further comprising generating vertical lift with the main rotor when the main rotor is in the autorotation mode. 
     
     
         13 . The method of  claim 11 , wherein the generating electrical energy step occurs when a specified cruise speed is achieved by the rotorcraft in horizontal flight. 
     
     
         14 . The method of  claim 11 , wherein the powering step occurs when the thrusters fail to receive energy from a primary energy source. 
     
     
         15 . The method of  claim 11 , further comprising propelling the rotorcraft in horizontal flight using a plurality of thrusters. 
     
     
         16 . The method of  claim 11 , wherein the powering step occurs to assist in providing vertical lift to the rotorcraft in an emergency landing. 
     
     
         17 . A rotorcraft with an anti-torque mode, comprising:
 a main rotor exerting a torque on a fuselage;   a first ducted fan having a horizontal stator deflected aft;   a second ducted fan having a horizontal stator deflected forward;   a third ducted fan having a vertical stator deflected inboard; and   a fourth ducted fan having a vertical stator deflected outboard,   wherein the ducted fans are operably positioned to cancel the torque exerted by the main rotor on the fuselage.   
     
     
         18 . The rotorcraft of  claim 17 , wherein the first and second ducted fans are forward of the third and fourth ducted fans. 
     
     
         19 . The rotorcraft of  claim 17 , wherein the ducted fans include both horizontal and vertical stators. 
     
     
         20 . The rotorcraft of  claim 17 , wherein the stators can be positioned to control the yaw of the rotorcraft.