Abstract:
An aircraft provides hovercraft power via fabric fans that produce lift for supporting the craft above an underlying support surface. Fabric fans are specially configured for maximum efficiency. In one embodiment, a helicopter utilizes the fan as part of a tail rotor assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Priority of U.S. Provisional Patent Application Ser. No. 61/445,431, filed Feb. 22, 2011, incorporated herein by reference, is hereby claimed. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable 
     REFERENCE TO A “MICROFICHE APPENDIX” 
     Not applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a craft such as a hovercraft that employs one or more specially configured hovercraft fans. 
     2. General Background of the Invention 
     There is a growing demand for quieter and more efficient aircraft and unmanned aerial vehicles or unmanned aerial vehicles or UAV&#39;s. Until now the centrifugal fan has been overlooked due to the heavy solid construction required for stability of the fans complex geometry. 
     The original hovercraft engineers in the late 1960&#39;s used a type of centrifugal fan as the best solution for the needs of that unique aircraft. However they failed to find a lightweight fan that was able to absorb the power needed and flexible enough to accommodate the gyrating craft motions. 
     On hovercraft and light aircraft in which not so quiet, lightweight propulsion is required the choice has been limited to multi-bladed axial fans of larger diameter. 
     The following is incorporated herein by reference: 
     YIHUA CAO, DONG LI, QIANG ZHANG, HANG BIAN, “Recent Development of Rotorcraft Configuration”,  Recent Patents on Engineering,  1, 49-70, 2007. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a craft, such as an aircraft or hovercraft that features a fabric fan that provides a high volume of air for lift and propulsion and using a quieter alternative to the much noisier axial propeller. Centrifugal fan arrangements have been established to have outstanding high volume flow and pressure characteristics. The primary use of conventional centrifugal fans has been in air-conditioning and heating ventilation units due to its superior low-noise operation. 
     A fabric fan of lightweight construction and superior low noise operation offers unique advantages to be applied in both conventional and new types of aircraft. Scalability of these easy to construct fabric fans are unlimited with regards to the size of aircraft built today. 
     Light aircraft have not applied the advanced characteristics of their larger jet propelled designs. The ability of a jet aircraft to provide pressurized air for thrust reversing, quick acting directional control as in the new F22 and stability wingtip jets as on the Harrier vertical take off and land (VTOL) fighter jet have long been desired but never conceived in a lighter, less expensive format for light aircraft. 
     The fan of the present invention, provides pressurized ducting around the entire craft. As in a jet aircraft, this pressurized air is used for stability, braking, steering in addition to lift and thrust. 
     The two primary problems preventing the widespread use of light aircraft is the lack of more convenient small airfields and the disturbing noise generated from conventional propellers. The adoption of the fabric fan of the present invention into a purpose built airframe will allow vertical take-off and landing (VTOL), omitting the need for runways. The low speed revolutions per minute (r.p.m.) could be between about 300-2000 r.p.m., more preferably between about 500 and 800 r.p.m. The extremely quiet nature of the fabric fan eliminates the second problem of excessive noise from light aircraft today. 
     The unmanned aerial vehicle market has been limited to the same propeller technology as light aircraft. The same reasons are that the centrifugal fan has until now been too heavy. An unmanned aerial vehicle using the propeller or fan of the present invention will allow unprecedented stealth and agility. The robust structure of the fabric fan of the present invention can absorb ballistic damage as does the bullet resistant aircraft shell. 
     The fabric fan of the present invention used in an unmanned aerial vehicle has the ability to take off vertically, hover on station effectively and fly transits with the economy of conventional unmanned aerial vehicles. 
     The fabric fan unmanned aerial vehicle of the present invention has extraordinary lift capacity that allows reconnaissance modules and conventional weapons to be mounted. 
     The fabric fan unmanned aerial vehicle of the present invention has the ability to scout below forest canopy, inside buildings and patrol at urban street level altitudes. 
     The fabric fan unmanned aerial vehicle of the present invention operates quiet enough to be undetected by an enemy. The fabric fan unmanned aerial vehicle of the present invention can land vertically with a central mounted weapon acting as a remote fire base. These same characteristics can also be utilized for rescue in hostile or dangerous environments. 
     There has been a lack of detectable progress in the development of a modern concept of “flying car” due to the same technical hurdles experienced by light aircraft. The total reliance of the present day aerospace design community on axial propellers has caused a huge (e.g. 50 year) set-back in light aircraft design progress. 
     The fabric fan of the present invention allows the actual creation of a flying car. The fabric fans, power and control of the flying car can provide more spacious interior while provided with a sleek styled body. 
     Automotive like seating and steering can be provided with a more robust attitude control via a forward mounted canard. Deployable wings may also be added if the demand for long range transits out of ground effect arises. 
     The hovercraft has gone into a design remission since shortly after its introduction in the 1950&#39;s. Those early designs utilized the centrifugal fan for both propulsion and lift due to its high flow and flat pressure characteristics. As the craft grew to absorb more horsepower, the custom built riveted aluminum and early fiberglass fans proved too fragile. As with light planes and airboats, they have since only utilized axial fans for thrust. Public outcry due to noise levels has prevented any widespread use of this otherwise highly efficient form of transportation. 
     Small recreational vehicles such as jet skis and all terrain vehicles have also been constrained due the noise and surface disturbance that occurs during operations. The fabric fan of the present invention will allow the creation of an amphibious all-terrain-vehicle design for recreational, rescue and personal transportation. Utilizing the high horsepower absorbing, lightweight centrifugal design will make new, marketable, recreational hovercraft possible. 
     The fabric fan air cushion recreational vehicle of the present invention will tread lightly on water or ground due to the nature of its air-cushion footprint and its low noise will prevent the negative effect of the other vehicles. 
     In accordance with the inventions there is provided an unmanned aerial vehicle and manned aircraft providing a fabric fan(s) with a shaft driven by a motor centrally (e.g. mounted). These fans of the present invention provide pressurized air flow directed in generating dynamic lift and thrust. The aircraft air-flow is distributed by an enclosed duct within the body shell. 
     A narrow open slot is provided around the periphery of each fan unit, this slot provides a high speed “momentum” curtain of moving air entrapping the air-cushion which forms underneath the vehicle while in ground effect. 
     Forward thrust air is expelled via rear open duct and across control rudders for directional control. Thrust air can be throttled by the operator or electronically, via a hinged door panel which allows controlled amount of thrust only when needed. 
     A forward mounted hinged vent in the aircraft pressurized duct is operator or electronically controlled to allow air breaking for controlled stops or rapid deceleration. 
     The proposed aircraft and unmanned aerial vehicle can fly free of ground effect due to the lift capacity of the fabric fans. Once airborne the aircraft can deploy conventional wings for more efficient long range transit. The fabric fans of the present invention can provide all thrust and some control via venting for this mode of operation. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein: 
         FIG. 1  is a schematic top view of a preferred embodiment of the apparatus of the present invention; 
         FIG. 2  is a bottom perspective view of a preferred embodiment of the apparatus of the present invention; 
         FIG. 3  is a perspective view of a preferred embodiment of the apparatus of the present invention; 
         FIG. 4  is an example of an aircraft that could be configured to operate as an embodiment of the apparatus of the present invention; 
         FIG. 5  is a perspective view of a preferred embodiment of the apparatus of the present invention; 
         FIG. 6  is a fragmentary view of a preferred embodiment of the apparatus of the present invention; 
         FIG. 7  is a fragmentary view of a preferred embodiment of the apparatus of the present invention; 
         FIG. 8  is a partial perspective view of a preferred embodiment of the apparatus of the present invention; 
         FIG. 9  is a partial perspective view of a preferred embodiment of the apparatus of the present invention; 
         FIG. 10  is a partial perspective exploded view of a preferred embodiment of the apparatus of the present invention; 
         FIG. 11  is a partial perspective view of a preferred embodiment of the apparatus of the present invention; and 
         FIGS. 12-15  are fragmentary view of a preferred embodiment of the apparatus of the present invention illustrating a stirrup assembly and its construction; and 
         FIG. 16  is perspective view of a stealth helicopter anti-torque fan. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1-5  show generally the preferred embodiment of the apparatus of the present invention, designated generally by the numeral  5  ( FIGS. 1 ,  2 )  6  ( FIG. 3 ),  7  ( FIG. 4 ), and  8  ( FIG. 5 ). 
     Aircraft  5  of  FIGS. 1 ,  2  is shown in a dual fan, longitudinal layout. This layout allows maximum lift while minimizing frontal area. The aircraft  5  can be an unmanned aerial vehicle or manned aircraft having a body or fuselage  10  with dual fabric fans  11 ,  12 . Each fan  11 ,  12  can be shaft driven by a central mounted motor or engine  14 , shafts  15 ,  16  and angle gearboxes  17 ,  18 . These fore and aft fabric fans  11 ,  12  provide pressurized air flow for dynamic lift and thrust. The aircraft air-flow is distributed by an enclosed duct within the body shell  10 . 
     The lightweight body/shell  10  can be surrounded by a structure such as a rigid alloy pipe structure  20  which holds strategically placed bumpers  21  (e.g. foam). Manual movement and landing can be supported by wheels  22  and forward and rear skids  23 . 
     A narrow open slot  24  can be provided in the vehicle bottom  25  around the periphery  26  of each fan unit  11 ,  12 . This slot  24  provides a high speed “momentum” curtain of air which entraps the air-cushion which forms underneath the vehicle while in a ground effect mode. Thrust air is expelled via rear open duct  27  across control rudders  28  for directional control. Thrust air can be throttled by the operator or electronically, via a hinged door panel  29  which allows controlled amount of thrust when needed. 
     A forward mounted hinged vent  30  in the aircraft pressurized duct is operator or electronically controlled to allow air breaking for controlled stops or rapid deceleration. 
     Directional control by the operator (or electronically) is via aft mounted rudders  28  placed in an aft facing duct  27 . Pitch and roll are controlled by the operator (or electronically) via control of lift fan air outlet slot  31 . A lift air outlet center panel  32  acts as a restrictor to vary the lift air vent opening along the periphery of each fan unit  11 ,  12 . Deployable wings  33 ,  34  are placed on the sides of the vehicle body/shell  10  for long range transits. 
     A center mounted generic weapon mount  35  and modular equipment trunk  36  can be located on a central portion of shell body  10  which houses the engine, fuel and control mechanicals. A multi capability camera, infrared or night vision, laser targeting pod  37  is located under center of the UAV. 
     Referring to  FIG. 3 , a personal flying car  6  is shown which can utilize a dual fabric fan  11 ,  12  and drive arrangement. Directional controls, stability and lift are as the vehicle  5  of  FIGS. 1 and 2 . The design would incorporate an automotive like stylish lightweight body shell  13 , enclosed interior cockpit with automotive controls and amenities. The attitude control is enhanced for high speed ground effect transit with the incorporation of a forward electronically controlled canard. 
     Referring to  FIG. 4 , a craft  7  that is similar to the flying car  6  of  FIG. 3  is shown but utilizing a more efficient skirted hovercraft concept. One fabric fan  11  or  12  can be used for reduced lift air and quiet propulsion air to be vented out the rear duct  51 . Control is augmented via side mounted operator controlled air vents  52 . Directional control and air breaking are similar to the vehicle of  FIGS. 1 and 2 . 
     Referring to  FIG. 5 , a hovercraft recreational vehicle  8  utilizing the same general dual fabric fan  11 ,  12  and drive arrangement of  FIGS. 1 and 2  with less horsepower and smaller fans than those required in  FIGS. 1 and 2 . Lift air can be reduced using a skirted (e.g. rubber fabric skirt) hovercraft hull  19 . More air can be directed for thrust. Control is augmented via side mounted operator controlled air vents  61  in both  FIGS. 4 and 5 . Directional control and air breaking are similar to the vehicle in  FIGS. 1 and 2 . 
       FIGS. 6-15  show more particularly the construction of the rotating structure  40  of each fan  11 ,  12 . Rotating structure  40  includes a pair of wheels  42 ,  46 . The upper wheel  42  provides an upper ring  43  supported by a plurality of radially extending spokes  44 . Upper wheel  42  is attached to hub  45 . Hub  45  can be generally cylindrically shaped and mounted upon drive shaft  41  which extends upwardly from gear box  17  or  18 . 
     In  FIG. 7 , the reference numeral  50  designates the rotational axis of hub  45  and rotating structure  40 . Arrows  39 ,  53 ,  54  show intake, intermediate and discharge air flow. Annular fan volute housing  38  helps control the flow of air from  39  to  53  to  54  as shown in  FIG. 7 . Lower wheel  46  provides a tapered annular concave surface  47 , lower ring  48 , and radially extending support panels  49  that extend between surface  47  and hub  45 . The rotating structure  40  includes a stirrup assembly  60  comprised of a plurality of stirrups  55  and a plurality of air foil panels  56 . Each air foil panel  56  attaches to stirrup  55  at stirrup panel  70 . Attachment openings  57  are provided on ring  43 . Similarly sized and spaced attachment openings  58  are provided on stirrup  55 . Likewise, openings  59  are provided on lower wheel  46 . 
     In  FIG. 6 , a fastener  75  is shown attaching each stirrup  55  to ring  43  and upper wheel  42 .  FIGS. 12-15  illustrate an exemplary construction for a stirrup  55 . Each stirrup  55  can provide panels  70 - 74  as shown in  FIGS. 12-15  and fold lines  64 - 69  as shown in  FIGS. 12-15 . Fabric stirrup sheet  63  is thus folded at fold line  64  as shown in  FIGS. 12-14  to provide a channel  62  through which air flows along the path designated by arrows  39 ,  53 ,  54  in  FIG. 7 . 
       FIG. 16  shows another embodiment of the apparatus of the present invention, designated generally by the numeral  90  and having airframe  85 . Fan  81  can be a fan as constructed in the embodiments of  FIGS. 1-15 . A centrifugal fan  81  constructed out of lightweight, strong flexible aramid or other advanced fabrics with semi-rigid and rigid shaped foils. The fan construction of the present invention minimizes fan weight and maximizes absorption to levels typical in light aircraft or UAV propulsion or large industrial air supply applications. 
     As shown in  FIGS. 8-15 , the fan consists of a rigid torque transferring hub  45  consisting of an upper open spoke structure extending to a retaining rim on the intake side of the fan and a solid cone shaped, lower half formed to the same diameter as the upper rim. The hub  45  can be constructed of fiber reinforced plastic, metal or plastic depending on ultimate loads required. 
     Attached to the periphery of the hub  45  upper and lower rim is a circular set of fabric “stirrups”  55  cut to the geometry shown in  FIGS. 8-15  and glued in a interlocking pattern (see  FIGS. 9-15 ). These stirrups  55  can be defined for any number of blades or blade angle. 
     These stirrups  55  form into a complete fan shroud or stirrup assembly  60 . Each stirrup  55  of the shroud  60  is folded to receive the curved blade  56  geometry precisely within the inside cusp (see  FIG. 11 ). Each fabric stirrup  55  receives a rigid formed airfoil blade  56  adhered in place (see  FIG. 11 ). 
     The assembly of these components forms rigid but forgiving fan geometry when spun as required for air moving fan. The use of preformed fabric pattern allows the optimization of fiber direction to resist operating loads and the interlocking nature of the stirrups share centrifugal forces. 
     As compared to conventional commercial fans which have a heavy, rigid fan shroud assembly, to define and maintain its geometry. This fabric fan uses its flexible shroud material only to retain the blade forms against the centrifugal forces trying to throw them outward. The self generating centrifugal forces stress the flexible fan assembly to maintain the desired geometry during rotation. 
     The anti-torque nature is in its application to the helicopter configuration, the small tail rotor this replaces to counter the torque imparted to the helicopter from the larger lift rotor. Stealth helicopter  90  anti-torque fan  81  is concealed from radar in a stealth helicopter airframe tail portion  89 . The helicopter airframe  85  has a port side, sliding (fore and aft) air-flow directional shutter  82 , and starboard, sliding (fore and aft) air-flow directional shutter  83 . The fabric fan thrust outlet airflow is directional and controlled by the pilot via flow directing shutters or vanes. These vanes can be cable controlled to redirect the airflow or thrust biased to either side or both sides air flow which is considered neutral. 
       FIG. 16  shows a fan intake radar shielding and foreign object damage (“FOD”) protection grate  84 . Airframe  85  can be a stealth helicopter airframe  85 . The helicopter  90  has a port anti-torque air-flow thrust direction  86 , and a starboard anti-torque air-flow thrust direction  87 . The fabric fan thrust outlet airflow is directional controlled by the pilot via flow directing shutters or vanes, these vanes can be cable controlled or powered directly from the normal pilot rudder pedals in the helicopter for the same directional control function as the tail rotor it replaces. 
     The primary challenge to helicopter design today is noise abatement, general simplicity and reduced pilot workload for control, the present invention application addresses these needs. 
     Many “Fan anti-torque” benefits are applicable to any non-stealth helicopters both present and future design. Fan anti-torque thrust can be used for added forward propulsion and pitch control as never before. Not only are the rotating fan blades protected from FOD and ground/building proximity strikes, but the nature of the fabric fan is more durable due to the flexibility inherent in the aramid fabric construction. The fabric fan can resist direct small arms fire and shrapnel. The fan constructions central use of anti-ballistic aramid fiber and the impact resistance of its flexible nature combine to make a rugged structure not susceptible to impact cracking and off-balance conditions due to its extreme lightweight. 
     “The noise from the tail rotor is considered as the main source of the rotorcraft high frequency noise. In addition, due to its increased weight and complex structure, it is not convenient.” See CAO, et al., “Recent Development of Rotorcraft Configuration”,  Recent Patents on Engineering,  1, 49-70, 2007. 
     The following is a list of parts and materials suitable for use in the present invention. 
     PARTS LIST 
     
       
         
               
               
               
               
             
           
               
                   
               
               
                   
                 Part Number 
                 Description 
                   
               
               
                   
               
             
             
               
                   
                  5 
                 aircraft 
                   
               
               
                   
                  6 
                 vehicle/craft 
                   
               
               
                   
                  7 
                 vehicle/craft 
                   
               
               
                   
                  8 
                 vehicle/craft 
                   
               
               
                   
                 10 
                 body/shell 
                   
               
               
                   
                 11 
                 fan 
                   
               
               
                   
                 12 
                 fan 
                   
               
               
                   
                 13 
                 automotive body/shell 
                   
               
               
                   
                 14 
                 engine 
                   
               
               
                   
                 15 
                 shaft 
                   
               
               
                   
                 16 
                 shaft 
                   
               
               
                   
                 17 
                 gearbox 
                   
               
               
                   
                 18 
                 gearbox 
                   
               
               
                   
                 19 
                 hull 
                   
               
               
                   
                 20 
                 rigid structure/pipe structure 
                   
               
               
                   
                 21 
                 bumper 
                   
               
               
                   
                 22 
                 wheel 
                   
               
               
                   
                 23 
                 skid 
                   
               
               
                   
                 24 
                 slot 
                   
               
               
                   
                 25 
                 bottom 
                   
               
               
                   
                 26 
                 periphery 
                   
               
               
                   
                 27 
                 rear duct 
                   
               
               
                   
                 28 
                 rudder 
                   
               
               
                   
                 29 
                 hinged door panel 
                   
               
               
                   
                 30 
                 hinged vent 
                   
               
               
                   
                 31 
                 air outlet slot 
                   
               
               
                   
                 32 
                 lift air outlet panel 
                   
               
               
                   
                 33 
                 wing 
                   
               
               
                   
                 34 
                 wing 
                   
               
               
                   
                 35 
                 weapon mount 
                   
               
               
                   
                 36 
                 trunk 
                   
               
               
                   
                 37 
                 pod 
                   
               
               
                   
                 38 
                 fan volute housing 
                   
               
               
                   
                 39 
                 intake air flow arrow 
                   
               
               
                   
                 40 
                 rotating structure 
                   
               
               
                   
                 41 
                 shaft 
                   
               
               
                   
                 42 
                 upper wheel 
                   
               
               
                   
                 43 
                 upper ring 
                   
               
               
                   
                 44 
                 spoke 
                   
               
               
                   
                 45 
                 hub 
                   
               
               
                   
                 46 
                 lower wheel 
                   
               
               
                   
                 47 
                 concave surface 
                   
               
               
                   
                 48 
                 lower ring 
                   
               
               
                   
                 49 
                 radially extending support panel 
                   
               
               
                   
                 50 
                 rotational axis 
                   
               
               
                   
                 51 
                 vent/rear duct 
                   
               
               
                   
                 52 
                 vent 
                   
               
               
                   
                 53 
                 arrow 
                   
               
               
                   
                 54 
                 arrow 
                   
               
               
                   
                 55 
                 stirrup 
                   
               
               
                   
                 56 
                 airfoil panel 
                   
               
               
                   
                 57 
                 attachment opening 
                   
               
               
                   
                 58 
                 attachment opening 
                   
               
               
                   
                 59 
                 attachment opening 
                   
               
               
                   
                 60 
                 stirrup assembly/shroud 
                   
               
               
                   
                 61 
                 vent 
                   
               
               
                   
                 62 
                 air flow channel 
                   
               
               
                   
                 63 
                 fabric stirrup sheet 
                   
               
               
                   
                 64 
                 fold line 
                   
               
               
                   
                 65 
                 fold line 
                   
               
               
                   
                 66 
                 fold line 
                   
               
               
                   
                 67 
                 fold line 
                   
               
               
                   
                 68 
                 fold line 
                   
               
               
                   
                 69 
                 fold line 
                   
               
               
                   
                 70 
                 panel 
                   
               
               
                   
                 71 
                 panel 
                   
               
               
                   
                 72 
                 panel 
                   
               
               
                   
                 73 
                 panel 
                   
               
               
                   
                 74 
                 panel 
                   
               
               
                   
                 75 
                 fastener 
                   
               
               
                   
                 81 
                 fan 
                   
               
               
                   
                 82 
                 shutter 
                   
               
               
                   
                 83 
                 shutter 
                   
               
               
                   
                 84 
                 Fan intake radar shielding and 
                   
               
               
                   
                   
                 FOD protection grate 
                   
               
               
                   
                 85 
                 airframe 
                   
               
               
                   
                 86 
                 Port anti-torque air-flow thrust 
                   
               
               
                   
                   
                 direction 
                   
               
               
                   
                 87 
                 Starboard anti-torque air-flow 
                   
               
               
                   
                   
                 thrust direction. 
                   
               
               
                   
                 89 
                 tail portion 
                   
               
               
                   
                 90 
                 helicopter 
               
               
                   
               
             
          
         
       
     
     All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. 
     The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.