Abstract:
The present invention concerns an aircraft having a plurality of lifting and thrust rotors, with an electric motor and an inverter for each motor. In order to provide an aircraft having a greater payload, connecting bars are provided between the motors. In that respect the invention is based on the realization that, if such connecting bars are arranged in the manner of a latticework, they can provide a light but nonetheless stable structure for the aircraft, and that structure can carry correspondingly greater loads.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is a continuation of and claims priority under 35 U.S.C. § 120 to U.S. patent application Ser. No. 10/934,634, entitled “AIRCRAFT,” filed Sep. 3, 2004, which in turn is a continuation-in-part of International Application No. PCT/EP03/02210, filed Mar. 5, 2003, which in turn claims priority to DE Application No. 102 09 881.6, filed Mar. 6, 2002. All of these applications are incorporated herein by reference in their entireties. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     This invention relates to an aircraft for lifting heavy loads, and more particularly, to a barge type aircraft with a plurality of electric lifting and thrusting motors that travels only a short distance above the ground.  
         [0004]     2. Description of the Related Art  
         [0005]     A crane is usually required for erecting high buildings and constructions. That naturally also applies to tower-like buildings such as wind power installations. It will be noted that wind power installations are becoming increasingly larger and this means that the cranes on the one hand must reach ever increasing heights and on the other hand move ever increasing masses. That in turn results in larger and heavier cranes. Those cranes are then in turn more and more expensive and the expenditure for transporting such a crane from one building site to another also rises, as also the expenditure for assembly and dismantling of the crane.  
         [0006]     An alternative is an aircraft which is capable of transporting the components of the building or construction, such as for example a wind power installation.  
         [0007]     DE 22 34 524 discloses a flying platform with a plurality of lifting and thrust rotors, with an electric motor for each rotor and an inverter for each motor.  
         [0008]     A disadvantage with that known aircraft however is that the electric motors are mounted to a common platform. That platform on the one hand is of a high inherent weight and, due to the construction involved, predetermines the possible numbers of motors and rotors respectively.  
       BRIEF SUMMARY OF THE INVENTION  
       [0009]     Therefore one object of the invention is to provide an aircraft able to carry a heavier payload than prior similar barge-type aircraft.  
         [0010]     In the aircraft in accordance with the invention, that object is attained by connecting bars between motors. In that respect the invention is based on the realization that a stable connection between the individual motors is admittedly required, but it is possible to save on the inherent weight of the platform when using a bar structure. The weight which is saved in that way, with the same carrying capacity on the part of the aircraft, is then available as an additional payload.  
         [0011]     In a preferred embodiment of the invention the power supply is implemented by way of at least one trailing cable. In that fashion the aircraft admittedly also has to lift the weight of the cable, but in return for that it does not need to carry costly and heavy energy storage devices. The power supply by way of a plurality of trailing cables which are preferably mounted to various locations on the aircraft means that reliable operation is still possible, even in the event of failure of a cable.  
         [0012]     In a particularly preferred feature the aircraft is controlled from the ground by way of a wireless or wired remote control system. In that respect it is also possible to provide two or more remote control systems which act alternately on the aircraft. In that way it is possible to effect rough positioning such as lifting of the load and fundamentally determining the direction of flight from the ground, while fine positioning, for example of a section of the pylon of the installation, is effected from the pylon in a position from which the procedure can be precisely monitored.  
         [0013]     In a preferred development of the invention the aircraft has landing feet with which it can be set down on the ground. For that purpose a resiliently mounted support plate is provided at the end of each rotor, which is remote from the shaft.  
         [0014]     In a particularly preferred feature the aircraft according to the invention has a device for automatic control of the flight attitude and/or the flight altitude. That device can also be coupled to a GPS system in order in that way to provide for automatically heading for a predeterminable position. In that way rough positioning of the aircraft according to the invention can be effected automatically.  
         [0015]     In order to reduce the inherent weight of the aircraft to the minimum possible extent, even when the flight control system is installed on the aircraft, the device is preferably arranged with connecting bars between at least two motors. In that case the device is particularly preferably arranged beneath the plane in which the bars extend between the motors. In that way, even in the case of a flight without a load, the aircraft has a low center of gravity which contributes to the stability of its flight attitude.  
         [0016]     In a preferred embodiment the motors and the inverters are structurally combined so that they can be pre-assembled and handled as a unit.  
         [0017]     In order to protect the electric cables which are required on the aircraft the connecting bars in a particularly preferred feature are hollow and the cables extend in the interior of the bars.  
         [0018]     So that the aircraft can be dimensioned as flexibly as possible and in dependence on the loads to be transported, fixed but releasable connections are provided between the connecting bars and the motors. That permits scaling of the aircraft according to the invention, insofar as, in dependence on the load to be transported, a desired number of motors is selected, the motors then being suitably connected by the connecting bars in the manner of a latticework to afford a stable aircraft.  
         [0019]     Advantageous embodiments of the invention are set forth in the appendant claims. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0020]     An embodiment by way of example of the invention is described in greater detail hereinafter with reference to the Figures in which:  
         [0021]      FIG. 1A  shows a top side simplified view of an aircraft according to the invention.  
         [0022]      FIG. 1B  shows a side elevation view of the aircraft of  FIG. 1A .  
         [0023]      FIG. 2  shows a simplified view of a motor according to the invention of the aircraft.  
         [0024]      FIG. 3  shows an end portion of a connecting bar according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]     In  FIGS. 1A and 1B , reference  10  denotes a motor, reference  12  denotes the rotor, such as a propeller, reference  14  denotes the inverter, reference  15  denotes a connecting bar and reference  16  denotes a control device for controlling the flight attitude or position, and/or the flight altitude.  
         [0026]     The aircraft according to the invention is here shown as being of a triangular basic shape.  
         [0027]     Some of the motors  10  are so arranged that the rotor  12  thereof rotates in a vertical plane. Depending on the direction of rotation of the motor  10  such a rotor  12  acts as a pusher rotor or a traction rotor. The direction of flight is accordingly influenced with those rotors.  
         [0028]     A power supply cable  25  provides power from the ground to the control device, which provides and controls power to the motors  10  via respective cables  26 .  
         [0029]     Arranged at the end points of the triangular shape are further motors  10 , the rotors  12  of which rotate in a substantially horizontal plane. They operate as lifting rotors and permit lifting of the load or flight at a predeterminable height.  
         [0030]     Associated with each motor  10  is an inverter  14  which permits individual actuation of each motor  10 . In that way the individual motors  10  can be actuated independently of each other and that therefore permits on the one hand the aircraft to be controlled in a very precise manner while on the other hand it permits the aircraft to be controlled independently of direction.  
         [0031]     The triangular shape is only shown as a variant, in this Figure. It will be appreciated that other polygons such as quadrangles, pentagons or any other shapes with a suitable arrangement of motors are possible in order to be able to lift and transport correspondingly large loads.  
         [0032]     Provided at the center of the aircraft is a control device  16  which on the one hand feeds electrical energy to the inverters  14  and thus the motors  10  and which on the other hand also influences the inverters  14  in order to produce a flight behavior corresponding to the control commands. It is also possible to integrate into that control device  16  an energy storage device which, for example in the event of a breakage of the trailing cable, still provides sufficient energy for the aircraft to make an emergency landing, in order to avoid an uncontrolled crash.  
         [0033]      FIG. 1B  shows a lifting system for use with the present invention. An electric motor  27  is provided suspended from the aircraft frame. The electric motor  27  can be suspended from any acceptable part of the frame, for example a central region directly below the control device  16 . The electric motor  27  can also be connected to other portions of the aircraft such as a frame coupled to the three corners of the aircraft. Extending below the electric motor  27  is a cable winch  29  and a cable having a hook  31 . The cable winch  29  has sufficient cable for extending to the ground when the aircraft is in flight at the expected altitude.  
         [0034]     The lift rotors  12  receive power via one or more cables  25  which are coupled to the ground. As the aircraft flies, the electrical power is provided on cables  25  which are connected to coiled wire supplies on the ground. As the aircraft flies upward, the cables  25  will naturally uncurl in order to provide the additional length needed to maintain the aircraft at a correct height above the ground and supply power via the ground connection. This provides the distinct advantage that the power needed to drive the motors  10  does not need to be carried by the aircraft. Instead, substantial weight savings is obtained because the weight of the fuel is not carried by the aircraft. Instead, the load weight can be increased based upon the fact that no fuel needs to be carried by the aircraft.  
         [0035]     Of course, other lifting structures besides the winch  29  can be provided on the aircraft. For example, the aircraft may contain one or more platforms for carrying a human operator or workers who will be assisting to assemble the structure being built. It may also include other support platforms.  
         [0036]     A control line may be coupled via cable  25 , or via wireless to the control device  16  for controlling the aircraft&#39;s altitude ALT and also its attitude ATT, such as when carrying a load  33  with the hook  31 . The various lift and thrust motors can be controlled via one or more remote control devices RC 1  and RC 2 , each of the devices RC 1  and RC 2  working either alone to control the device, or simultaneously, in which one of the control devices RC 1  controls the lift mechanism and the other control device RC 2  controls the directional thrust motors.  
         [0037]      FIG. 2  shows a side view of a motor  10  according to the invention. A rotor  12  is connected to that motor  10  by way of a shaft  32 . Provided at the end of the motor  10 , which is opposite to the shaft  32 , is a spring leg  22 , with a support foot  20  being mounted to the end of the spring leg  22 , which is remote from the motor. According to the position of installation illustrated in this Figure, this involves a lifting motor. When the aircraft according to the invention goes down therefore the support foot  20  will firstly come into contact with the ground and the remaining part of the aircraft will move downwardly against the pressure of the spring leg  22 . In that way the aircraft according to the invention can land on the ground without the housing of the motor  10  being exposed to the risk of damage or even only rough dirty contamination.  
         [0038]      FIG. 3  shows a portion of a connecting bar  15  according to the invention. The connecting bar  15  has a holder  18  with which it can be fixedly but releasably connected for example to a motor  10  in order to be able to construct an aircraft according to the invention. A cable  26  is illustrated within the connecting bar  15  which is of a hollow nature. That arrangement of the cable  26  in the connecting bar  15  provides that the cable is guided in a protected condition within the connecting bar  15  and thus this drastically reduces the risk of damage to the cable  26 , such risk being permanently present precisely in the rough conditions of a building site.  
         [0039]     The cable  26  issues from the connecting bar  15  at the end thereof and thus near the motor  10  and can be connected with the wires  28 . In that way none of cable  26 , or in some cases, only a short portion of the cable  26  between the end of the connecting bar  15  and the motor  10  is freely accessible. Here the risk of damage can be reduced by suitably guiding the cable  26  within the frame formed by the aircraft. It will be appreciated that this cable can also be directly connected to the inverter  14  which forms a structural unit with the motor  10 .  
         [0040]     However, guiding a cable in such a way is also advantageous when the inverter or inverters  14  are associated with the control device  16 . In that case the cables  26  run from the control device  16  with the inverters  14  to the motors  10 .  
         [0041]     In the described aircraft the number of lifting rotors is preferably markedly greater than the number of pusher rotors. For example the ratio of the number of lifting rotors to the thrust rotors can be in the range of between 5:1 and 10:1. Further, the lifting rotors can be of significantly more power than the pusher rotors. The thrusting rotors can be small and positioned to reduce the number needed.  
         [0042]     All of the above U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet, are incorporated herein by reference, in their entirety.  
         [0043]     From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.