Method and apparatus for lifting a payload

Abstract

A method and apparatus for lifting a payload wherein a first mechanical-rotor is driven by an internal combustion engine. A portion of the mechanical work developed by the internal combustion engine is used to generate electrical power, which is either stored in a battery or used to power an electric motor that drives a second rotor. Thrust developed by the mechanical and electrical rotors is directed downward to provide lift for the payload.

What is claimed is: 
     
         1 . A method for lifting a payload comprising:
 powering a first mechanical-rotor using a first internal combustion engine;   generating electrical power using the first internal combustion engine;   storing the electrical power in an electricity-storage-device;   powering a first electrical-rotor using electrical power stored in the electricity-storage-device;   applying to the payload in a substantially vertical direction a portion of a thrust generated by the first mechanical-rotor;   applying to the payload in a substantially vertical direction a portion of a thrust generated by the first electrical-rotor;   sensing an attitude of the payload; and   adjusting the power to the first electrical-rotor according to the sensed attitude.   
     
     
         2 . The method of  claim 1  further comprising:
 adjusting the power applied to the first mechanical-rotor when the attitude cannot be corrected by adjusting the power to the first electrical-rotor. 
 
     
     
         3 . The method of  claim 1  further comprising:
 converting electrical power stored in the electricity-storage-device to mechanical work; and 
 applying the mechanical work to the first mechanical-rotor. 
 
     
     
         4 . The method of  claim 1  further comprising:
 adjusting a power delivered by the first internal combustion engine to the first mechanical-rotor in order to increase the vertical thrust applied to the payload. 
 
     
     
         5 . The method of  claim 1  further comprising:
 directing an additional portion of the thrust generated by the first mechanical-rotor in a direction substantially opposite to a desired path of flight; and 
 generating lift using a lifting surface to support the payload using airflow resulting from movement in the desired path of flight. 
 
     
     
         6 . The method of  claim 5  further comprising removing power from the first electrical-rotor. 
     
     
         7 . The method of  claim 1  further comprising:
 powering a second mechanical-rotor using a second internal combustion engine; and 
 directing a substantial portion of a thrust developed by the second mechanical-rotor in a direction substantially opposite to a desired path of flight; and 
 generating lift using a lifting surface to support the payload using airflow resulting from movement in the desired path of flight. 
 
     
     
         8 . The method of  claim 1  further comprising:
 directing an additional portion of the thrust generated by the first electrical-rotor in a direction opposite to a desired path of flight; and 
 generating lift using a lifting surface to support the payload using airflow resulting from movement in the desired path of flight. 
 
     
     
         9 . The method of  claim 8  further comprising:
 removing power from the first mechanical-rotor; and 
 continuing to operate the first internal combustion engine in order to generate electrical power. 
 
     
     
         10 . The method of  claim 1  wherein generating electrical power comprises:
 receiving mechanical power from the first internal combustion engine; 
 altering a rotational speed of the mechanical power; 
 converting a portion of the speed-altered mechanical power to electrical power; and 
 conveying a substantially remaining portion of the speed-altered mechanical power to the first mechanical-rotor. 
 
     
     
         11 . The method of  claim 1  wherein generating electrical power comprises:
 receiving mechanical power from the first internal combustion engine; 
 converting a portion of the mechanical power to electrical power; and 
 conveying a substantially remaining portion of the mechanical power to the first mechanical-rotor. 
 
     
     
         12 . The method of  claim 10  further comprising:
 conveying a portion of the electrical power to a first electrical-rotor; and 
 conveying an additional portion of the electrical power to a second electrical-rotor. 
 
     
     
         13 . The method of  claim 10  further comprising:
 conveying a portion of the electrical power to a first electrical-rotor; and 
 storing an additional portion of the electrical power for future use. 
 
     
     
         14 . The method of  claim 13  further wherein storing an additional portion of the electrical power comprises:
 converting the electrical power to a direct current; and 
 charging a storage cell according to the direct current. 
 
     
     
         15 . A multi-rotor airframe comprising:
 energy storage device capable of storing electrical power;   first internal combustion engine;   first rotor capable of generating thrust according to mechanical work applied thereto and disposed to direct a portion of its thrust in a substantially downward direction;   first motor-generator mechanically coupled to the first rotor;   first mechanical coupler disposed to enable selective application of mechanical power from the first internal combustion engine to the first motor-generator;   first motor controller capable of receiving electrical power generated by the first motor-generator and directing it to the energy storage device;   second rotor capable of generating thrust according to mechanical work applied thereto and disposed to direct a portion of its thrust in a substantially downward direction;   second motor-generator coupled to the second rotor;   second motor controller capable of receiving electrical power from the energy storage device and directing said electrical power to the second motor-generator in accordance with a first correction signal;   attitude sensor that is capable of generating an attitude signal according to an attitude exhibited by the airframe; and   flight controller that generates a first correction signal according to the attitude signal and an intended attitude value and wherein the first correction signal is directed to the second power controller.   
     
     
         16 . The multi-rotor airframe of  claim 15  wherein first mechanical coupler comprises a clutch. 
     
     
         17 . The multi-rotor airframe of  claim 15  wherein first mechanical coupler comprises:
 clutch; and 
 gear-box for adjusting the angular speed of the mechanical power applied to the first motor-generator. 
 
     
     
         18 . The multi-rotor airframe of  claim 15  wherein the first motor controller is further capable of receiving electrical power from the energy storage device and directing it to the first motor-generator and wherein the first motor-generator is capable of converting the electrical power to mechanical power and applying said mechanical power to the first rotor. 
     
     
         19 . The multi-rotor airframe of  claim 15  wherein the flight controller is capable of generating a second correction signal according to an attitude exhibited by the airframe and according to the first correction signal and wherein the first power controller further includes a correction input and is capable of causing electrical power to be applied to the first motor-generator according to said second correction input when the attitude signal indicates there is an attitude error and the first correction signal indicates that it is at a control limit. 
     
     
         20 . The multi-rotor airframe of  claim 15  wherein the flight controller is capable of generating a second correction signal according to an attitude exhibited by the airframe and according to the first correction signal and wherein the first internal combustion engine further includes a throttle control input and is capable of adjusting power to be applied to the first rotor according to said second correction input when the attitude signal indicates there is an attitude error and the first correction signal indicates that it is at a control limit. 
     
     
         21 . The multi-rotor airframe of  claim 15  wherein the first internal combustion engine further includes a throttle control input and the flight controller is capable of generating a lift signal that, when received by the throttle control input, causes the first internal combustion engine to increase power applied to the first rotor. 
     
     
         22 . The multi-rotor airframe of  claim 15  further comprising a lifting surface attached to the airframe and which is capable of generating lift in a substantially vertical direction when subject to an airflow and further comprising a tilt-mechanism that is disposed to enable the first rotor to tilt about an axis substantially parallel to a pitch-axis of the airframe and wherein the flight controller is further capable of generating a tilt signal and wherein the tilt-mechanism is capable of responding to the tilt signal by tilting the first rotor so as to cause a portion of its thrust to be directed in a direction opposite to a desired direction of flight. 
     
     
         23 . The multi-rotor airframe of  claim 22  further comprising a speed sensor capable of generating a speed signal according to a forward path of the airframe and wherein the flight controller is further capable of generating an power-down signal when the speed signal indicates that the forward speed of the airframe will result in sufficient lift generation by the lifting surface to support the airframe and wherein the second power controller includes a power-down input and is capable to discontinuing application of electrical power to the second motor-generator when the power-down is active. 
     
     
         24 . The multi-rotor airframe of  claim 15  further comprising a forward thruster comprising at least one or more of an internal combustion engine, a motor-generator and/or an electric motor coupled to a rotor and wherein the thruster includes an enable signal that is controlled by the flight controller. 
     
     
         25 . The multi-rotor airframe of  claim 15  further comprising a payload bay for storing a secondary payload.