Patent Publication Number: US-2023144699-A1

Title: Vehicle having multiple configurations including road configuration and flying configuration based upon rotor position

Description:
FIELD OF THE INVENTION 
     The present disclosure relates to Vertical Take-Off and Landing (VTOL) flying cars, and more particularly to roadable VTOL flying cars configured to take off, fly and land like helicopters or gyrocopters using single main rotor configuration or twin rotor configuration with clockwise (CW) and counter-clockwise (CCW) tandem rotors and/or coaxial rotors, having improved efficiency and a simple folding mechanism. 
     BACKGROUND 
     Since the Wright brothers first manned flight people dream for compact flying vehicle “flying car” to be able to fly over the air without roads or traffic jams with vertical takeoff and landing capability like in the “Back to the future” movie, but this challenge become very complicated due to the air vehicle physical size and energy/fuel consumption, wherein the air vehicle efficiency for both fixed-wings (airplanes) and rotary-wings (helicopter/gyrocopter) depends on ratio between takeoff weight and wings/rotor surface area and significantly degrades performance when this ratio become high. Some prior art “flying car” are described in US patents U.S. Pat. Nos. 8,511,603, 6,745,977, 6,457,670 and U.S. Ser. No. 10/518,595, as well as in US patent application US20080067284. 
     As result all known in the art compact “flying car” prototypes suffer from efficiency problems or may have a very complicated folding mechanism for wings/rotor folding and as result are very expensive, dangerous and have limited flight time. 
     The state-of-the-art flying cars prototypes divided in two main categories:
         1. Small flying vehicles without roading capability.   2. Foldable air vehicles with roading capability.       

     The category (1) flying vehicles are commonly using known in art VTOL schemes like (a) helicopters by making them small form factor (for example GEN H-4 helicopter) or like (b) multi rotor copters with 2 or more fixed pitch rotors using drone scheme in large form factor (for example “hoversurf scorpion 3” known also known in art as hoverbike), wherein both of this vehicles types have high weight to rotor surface ratio and as result they suffer from low efficiency that cause many problems like: low flight duration (usually up to 20 min), low takeoff weight (can carry only 1 person), high operational cost and safety issues. 
     The category (2) flying vehicles are subdivided into several categories such as:
         a. Roadable aero plane—this type can use (a) foldable fixed wings scheme like (Terrafugia, “Samson switchblade” and others) or (b) rotatory wing gyrocopters like (PAL-V and others), this vehicle type suffers from complicated folding mechanism that effect on cost and safety of flight and don&#39;t have VTOL capability that makes it necessary to use runways for takeoff and landing.   b. Roadable aero planes with vertical takeoff and landing capability that includes foldable wings and rotors, this type of vehicles are so complicated that up to date nobody made a full-scale working prototype while even if do so this vehicle type will suffer from many problems including safety and cost.   c. Roadable helicopters, such as described in U.S. Pat. No. 5,915,649 and like—this type of vehicles uses classic helicopter scheme, where the foldable mechanism is mechanical and thereby complex, wherein the main single rotor or coaxial counterrotating rotors are located at the middle of the vehicle. This type of prior art vehicles provides very complicated folding mechanisms, and additional complexity in the form of the mechanical folding and unfolding mechanism of the main rotor, where each blade has a separate folding/unfolding mechanism located at the middle of the blades and as result each blade suffers from high mechanical stress. As result, these types of vehicles are yet to show a full-scale working prototype.       

     There is therefore a need, and it would be advantageous to provide roadable VTOL flying vehicles that are configured to take off, fly and land like helicopters or gyrocopters, as well as drive on common roads like common cars. It would be advantageous to provide the roadable VTOL flying vehicles with an efficiency and simple folding mechanism. 
     SUMMARY 
     A principal intention of the present disclosure is to provide a roadable VTOL (Vertical Take-Off and Landing) flying vehicles, configured to take off and land like helicopters or gyrocopters with a single main rotor and a simple folding mechanism or by using twin rotors with clockwise (CW) and counter-clockwise (CCW) in tandem configuration having improved efficiency and a simple folding mechanism. The improved efficiencies are achieved by substantially increasing the rotor surface area with respect to the state of prior art designs of flying vehicles (up to more than 8 times and even more) without oversizing the vehicle dimensions. This is achieved by using a balanced single rotor with two balanced blades (see  FIG.  1   a   ), or a balanced twin-rotors helicopter scheme having 2 rotors respectively positioned at the leading and trailing ends of the vehicle (as shown in  FIG.  1   c   ). 
     The single rotor and the rotary wings of the twin rotor provide lifting power of the vehicle, and can be propelled to deliver forward thrust when the vehicle is airborne for forward flight and backward thrust when the vehicle is airborne for backward flight. 
     The calculation of the lifting power of the vehicle that is generated by a single rotor and the twin rotors that is directly proportional to the surface area (S) covered by the rotating rotor(s), are as follows:
         The surface area covered by a single rotor, as shown in  FIG.  1   a   , is calculated as follows:       

     
       
         
           
             S 
             = 
             
               π 
               * 
               
                 
                   ( 
                   
                     vehicle_length 
                     2 
                   
                   ) 
                 
                 2 
               
             
           
         
       
         
         
           
             The surface area covered by a twin rotors system, as shown in  FIGS.  1   c ,  1   d  and  1   e   , is calculated as follows: 
           
         
       
    
         S= 2π*vehicle_length 2  
 
     According to the present disclosure, both the propulsion generation mechanism and the rotor folding mechanism are implemented using the same motors that spin the rotors during takeoff and flight, are also used to park and lock them during road-configuration operation. 
     This combination is simple, durable, effective, and inexpensive, wherein the complicated folding mechanism, as provided by prior art systems, is replaced by an electronic position control subsystem configured to park the and lock the rotor(s), while in a road-configuration (as shown on  FIGS.  1   a ,  1   b  and  1   c   ), and simply convert the vehicle to flying mode by unlocking the blades, speeding up the motor and take off (as shown, for example in  FIG.  1   d   ). It should be appreciated that there is an additional mechanism (not shown) used to secure and cover the rotor(s) during road-configuration operation. 
     The flight control and steering, while in air-born mode, is achieved by using any method or technique, known in the art, for controlling the air-born vehicle, using either variable or fixed pitch rotors. The flight control methods may include, without limitations, the following methods: (1) using swashplate for variable pitch rotors; (2) using rotor tilt control for fixed pitch rotors by implementing any known on the art technique of rotors tilting, including, without limitations, bi-copter scheme, wherein the rotors can be tilted separately or both; and (3) by adding additional maneuvering motors and/or any controllable aerodynamical surfaces. 
     In variations of the present disclosure, a single-blade rotor, such as shown in  FIG.  2   a   , is used, or multiple-blades rotors with automatic folding capability are used, such as shown in  FIGS.  2   b  and  2   c    are used, all of which rotors may embed any known in the art passive or active folding mechanism. 
     In variations of the present disclosure, one or both of twin tandem rotors are coaxial rotors with pair of matching counterrotating rotors such as shown in  FIG.  4   a   , are used. 
     In variations of the present disclosure, there is an additional rotor that provides the vehicle with an additional forward thrust, such as the two-blades rotors shown in  FIG.  4     b.    
     Optionally, the propulsion system may be using a hybrid (fuel and electric) engine, wherein the fuel engine is used as an electrical generator to supply the system power, wherein said fuel engine may be fully separated or be used to drive the car wheels during road-configuration operation by using any know in art hybrid engine scheme as shown in  FIG.  5     d.    
     It should be noted that in variations of the present disclosure the main propulsion system uses fuel engine, while the electrical motor is used to: (1) unfold and park the rotors; (2) start fuel engine and (3) be used as secondary backup system to continue the flight if the fuel engine fails as shown in  FIG.  5     c.    
     It should be noted that in variant of the present innovation the rotors driven independently using separate propulsion system each like shown in  FIG.  5     a.    
     It should be noted that in variant of the present innovation the rotors driven synchronously with common propulsion system like shown in  FIGS.  5   b    and  5   c.    
     According to teachings of the present disclosure, there is provided a roadable VTOL flying vehicle having a road-configuration and a flight-configuration. The roadable VTOL flying vehicle includes:
         a roadable vehicle;   at least one rotor having at least one blade, the rotor is rotatably attached to an upper section of the roadable vehicle of the flying vehicle;   at least one motor configured to operatively rotate the least at least one rotor;   at least one angular position sensor configured to detect the angular position of each of the at least one rotor; and   a vehicle control sub-system configured to affect automatic transformation of the flying vehicle from the road-configuration to the flight-configuration and from the flight-configuration to the road-configuration,   wherein the vehicle control sub-system is configured bring the at least one rotor into a parking state, when in road-configuration.       

     Optionally, when the at least one rotor is in the parking state, the control sub-system is configured to position the respective at least one blade within the vertical space situated above the roadable vehicle of the flying vehicle. Typically, when the at least one rotor is in the parking state position, the at least one rotor is locked in position. 
     Optionally, the at least one blade is foldable, wherein when in a flight-configuration the blade is unfolded, and when in road-configuration the blade is folded. Optionally, the blade may unfold automatically by a centrifugal force, when changing from road-configuration to flight-configuration. Optionally, the blade may be folded automatically by a biassing force when changing from flight-configuration to road-configuration, wherein the biassing force may be formed by at least one spring. 
     The vehicle control sub-system may be configured to fold the at least one foldable blade when changing from flight-configuration to road-configuration. 
     The vehicle control sub-system may be configured unfold the at least one foldable blade when changing from road-configuration to flight-configuration. 
     The control sub-system may determine that the at least one rotor is in the parking state position using the at least one angular position sensor. 
     The at least one rotor may be a single-blade rotor, wherein the single-blade is balanced by a counter-weight. 
     Optionally, when the at least one rotor is a two-rotors system, the pair of rotors may be positioned in a tandem configuration, and wherein each rotor consists of a single blade balanced by a respective counter-weight,
         wherein the pair of rotors may be matching and counterrotating rotors;   wherein each of the rotors may include a single blade balanced by a respective counter-weight;   wherein each of the rotors may include at least two blades;   wherein each of the rotors may include a pair of coaxial rotors, and wherein each of the coaxial rotors includes each pair coaxial rotors a pair of matching and counterrotating rotors;   wherein each of the pair of rotors may be coupled by a respective motor configured to operatively rotate the respective rotor, wherein each of the motors is coupled by a respective angular position sensor, and wherein the pair of rotors are either synchronous or asynchronous; and   wherein the pair of rotors may be coupled by a single rotating-motor configured to operatively rotate both rotors, wherein the rotating-motor is coupled by an angular position sensor, wherein the pair of rotors are synchronous and wherein the rotating-motor may also be coupled by another supporting motor selected from a group of power source including a fuel motor, another electric power source, and/or a hybrid power source.   The pair of rotors may be matching and counterrotating rotors;   wherein each of the rotors may include a single blade balanced by a respective counter-weight,   wherein each of the pair of rotors may be coupled by a respective motor configured to operatively rotate the respective rotor, wherein each of the motors is coupled by a respective angular position sensor, and wherein the pair of rotors are either synchronous or asynchronous;       

     When at least one rotor is a two-rotors system and the pair of rotors may be positioned in a tandem configuration, wherein each rotor consists of a single blade balanced by a respective counter-weight, the pair of rotors may be coupled by a single rotating-motor configured to operatively rotate both rotors, wherein the rotating-motor is coupled by an angular position sensor, and wherein the pair of rotors are synchronous, the rotating-motor may also be coupled by another supporting motor selected from a group of power source including a fuel motor, another electric power source, and/or a hybrid power source. 
     When at least one rotor is a two-rotors system and the pair of rotors may be positioned in a tandem configuration, wherein each rotor consists of a single blade balanced by a respective counter-weight, the pair of rotors may be coupled by a single rotating-motor configured to operatively rotate both rotors, wherein the rotating-motor is coupled by an angular position sensor, and wherein the pair of rotors are synchronous, the pair of rotating-motors may be driven by a controlled power source, and wherein the controlled power source include:
         a power control unit configured to monitor and coordinate the electric power within the roadable VTOL flying vehicle;   a rechargeable battery;   a power electric motor configured to supply electric power to the roadable VTOL flying vehicle; and,   and an additional power source configured to drive the power electric motor,   wherein when in road-configuration, the additional power source is configured to drive the wheels of the roadable vehicle; and   wherein when in flight-configuration, the power control unit is configured to direct electric power from the power electric motor to the rotating-motors that are configured to respectively operate the rotors;   wherein optionally, the additional power source is configured to activate the power electric motor to thereby recharge the rechargeable battery;   wherein optionally, when the additional power source is silent, the power control unit directs rechargeable battery to providing electric power;   wherein optionally, when in flight-configuration, the additional power source is configured to activate the power electric motor to thereby recharge the rechargeable battery;   wherein optionally, when in flight-configuration, the additional power source is configured generate mechanical energy to drive the power electric motor; and   wherein optionally, the additional power source, the power electric motor and the rechargeable battery are configured to operate in a hybrid configuration.       

     Optionally, when at least one rotor is a two-rotors system and the pair of rotors may be positioned in a tandem configuration, wherein each rotor consists of a single blade balanced by a respective counter-weight, the pair of rotors may be coupled by a single rotating-motor configured to operatively rotate both rotors, wherein the rotating-motor is coupled by an angular position sensor, wherein the pair of rotors are synchronous, the rotating-motor may also be coupled by another supporting motor selected from a group of power source including a fuel motor, another electric power source, and/or a hybrid power source, and 
     wherein the pair of rotors are configured to operate as intermeshing rotors. Optionally, the roadable VTOL flying vehicle further including a parachute configured to accommodate an emergency parachute. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become fully understood from the detailed description given herein below and the accompanying drawings, which are given by way of illustration and example only and thus not limitative of the present disclosure, and wherein: 
         FIG.  1   a    is a side view illustration of an example roadable VTOL flying vehicle, according to aspects of the present disclosure, the flying vehicle including a single two-blades rotor being in a parked state. 
         FIG.  1   b    is a side view illustration of another example roadable VTOL flying vehicle, according to aspects of the present disclosure, the flying vehicle including a single mono-blade rotor being in a parked state. 
         FIG.  1   c    is a side view illustration of another example roadable VTOL flying vehicle, according to aspects of the present disclosure, wherein the flying vehicle including two rotors are in a tandem configuration, wherein each rotor consists of a single blade, and the rotors are shown in a parked state. 
         FIG.  1   d    is an elevated rear perspective view illustration of the roadable VTOL flying vehicle as shown in  FIG.  1     c.    
         FIG.  1   e    illustrates the roadable VTOL flying vehicle, as shown in  FIG.  1   d   , wherein the rotors are shown in a rotating state, and wherein the surface area covered by each rotor is illustrated. 
         FIG.  2   a    illustrates an example single blade rotor, according to aspects of the present disclosure. 
         FIG.  2   b    illustrates an example two blades rotor, according to aspects of the present disclosure, wherein the blades are shown in parking position. 
         FIG.  2   c    illustrates an example three blades rotor, according to aspects of the present disclosure, wherein the blades are shown in parking position. 
         FIG.  3   a    is a side view schematic illustration of another example roadable VTOL flying vehicle, according to aspects of the present disclosure, wherein the roadable VTOL flying vehicle includes a pair of tandem, counter-rotating rotors, each having a pair of foldable blades, and wherein each blade is near or equal to the length of the roadable vehicle. The example roadable VTOL flying vehicle, 
         FIG.  3   b    illustrates the roadable VTOL flying vehicle, as shown in  FIG.  3   a   , wherein the rotors are shown in a rotating state (flight-configuration), and wherein the surface area covered by each rotor is illustrated. 
         FIG.  3   c    is a top view illustration of the roadable VTOL flying vehicle shown in  FIG.  3   a   , wherein the rotors are shown in a folded state (road-configuration), and wherein the surface area covered by each rotor is illustrated. 
         FIG.  3   d    is a top view illustration of the roadable VTOL flying vehicle shown in  FIG.  3   a   , wherein the rotors are shown in an unfolded state (flight-configuration), and wherein the surface area covered by each rotor is illustrated. 
         FIG.  4   a    is a side view illustration of another example roadable VTOL flying vehicle, according to aspects of the present disclosure, wherein both of twin tandem rotors are coaxial rotors. 
         FIG.  4   b    illustrates the roadable VTOL flying vehicle, as shown in  FIG.  4   a   , wherein the roadable VTOL flying vehicle further includes an additional multiple-blades rotor that provides the vehicle with an additional forward thrust. 
         FIG.  5   a    is a schematic illustration of an example asynchronous tandem twin-rotors, according to aspects of the present disclosure, wherein each of the twin rotors is driven by a single motor that is coupled with an angular position sensor. 
         FIG.  5   b    is a schematic illustration of an example synchronous twin-rotors propulsion system, according to aspects of the present disclosure, wherein both rotors are operated by a single motor that is coupled with an angular position sensor. 
         FIG.  5   c    is a schematic illustration of an example synchronous twin rotors propulsion system, wherein the twin rotors are operated by a hybrid motorized system, including a single electric motor that is coupled with an angular position sensor and a fuel motor. 
         FIG.  5   d    is a schematic illustration of an example hybrid, synchronous or asynchronous twin rotors propulsion system, wherein, while in road-configuration operation, the hybrid motorized system is also used to drive the wheels of the vehicle. 
         FIG.  6    illustrates the roadable VTOL flying vehicle, as shown in  FIG.  1   c   , wherein the twin tandem rotors are configured to operate as intermeshing rotors. 
         FIG.  7    illustrates an example two blades rotor, according to aspects of the present disclosure, wherein parachute container mounted above the twin tandem rotors system, such as shown by way of example only in  FIG.  1     c.    
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided, so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
     An embodiment is an example or implementation of the disclosures. The various appearances of “one embodiment,” “an embodiment” or “some embodiments” do not necessarily all refer to the same embodiment. Although various features of the disclosure may be described in the context of a single embodiment, the features may also be provided separately or in any suitable combination. Conversely, although the disclosure may be described herein in the context of separate embodiments for clarity, the disclosure may also be implemented in a single embodiment. 
     Reference in the specification to “one embodiment”, “an embodiment”, “some embodiments” or “other embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least one embodiment, but not necessarily all embodiments, of the disclosures. It is understood that the phraseology and terminology employed herein are not to be construed as limiting and are for descriptive purpose only. 
     Meanings of technical and scientific terms used herein are to be commonly understood as to which the disclosure belongs, unless otherwise defined. The present disclosure can be implemented in the testing or practice with methods and materials equivalent or similar to those described herein. 
     It should be noted that orientation related descriptions such as “bottom”, “up”, “upper”, “down”, “lower”, “top” and the like, assumes that the associated item, such as the flying car or a portion thereof, is in a road-configuration. 
     Reference is made back to the drawings.  FIG.  1   a    is a schematic side view illustration of an example roadable VTOL flying vehicle  100 , according to aspects of the present disclosure, the flying vehicle  100  includes a single two-blades ( 112   a ,  112   b ) rotor  110  being in either a parked state or a flying-configuration. One or both blades ( 112   a ,  112   b ) may be foldable blades. The rotor  110  is configured to rotate by a motor  114 , wherein rotor  110  rotates about the axis of an axle  115  that is affixed to the upper section of the roadable vehicle  50  of flying vehicle  100 . It should be appreciated that the roadable vehicle  50  can be based on any common roadable vehicle, pending on its weight. 
     Roadable VTOL flying vehicle  100  has a length L V , wherein, preferably, the wingspan L R  of the two-blades ( 112   a ,  112   b ) of rotor  110  does not exceed length L V  of the roadable vehicle  50  of flying vehicle  100 . Hence, flying vehicle  100  may behave on the road, while in a roadable-configuration, like any other ordinary vehicle. 
       FIG.  1   b    is a schematic side view illustration of another example roadable VTOL flying vehicle  101 , according to aspects of the present disclosure, the flying vehicle  100  includes a single-blade  112   a  rotor  111  that is balanced by a counter-weight  118 , wherein rotor  111  is in either a parked state or a flight-configuration rotational state. Blade  112   a  may be a foldable blade. The rotor  111  is configured to rotate by a motor  114 , wherein rotor  111  rotates about the axis of an axle  115  that is affixed to the upper section of the roadable vehicle  50  of flying vehicle  100 . 
     Roadable VTOL flying vehicle  101  has a length L V , wherein, preferably, the diameter (between positions  113  and  113 ′) of the imaginary circle drawn by the tip  113  of blade  112   a  of rotor  111  does not longer than the length L V  of the roadable vehicle  50  of flying vehicle  101 . Hence, flying vehicle  101  may behave on the road, while in a road-configuration, like any other ordinary vehicle. 
       FIG.  1   c    is a schematic side view illustration of another example roadable VTOL flying vehicle  200 , according to aspects of the present disclosure, wherein flying vehicle  200  includes two rotors ( 210   f ,  210   r ) positioned in a tandem configuration, wherein each rotor ( 210   f ,  210   r ) consists of a single blade ( 212   f ,  212   r ), and wherein the rotors ( 210   f ,  210   r ) are shown in a parked state. A front motor  214   f  is configured to activate the front rotor  210   f , and a rear motor  214   r  is configured to activate the rear rotor  210   r . It should be noted that the pair of rotors ( 310   f ,  310   r ) are matching and counterrotating rotors. The front rotor  210   f  is configured to rotate about the axis of a front axle  215   f  that is affixed to the front section of a static bench  216 , and the rear rotor  210   r  is configured to rotate about the axis of a rear axle  215   r  that is affixed to the rear section of static bench  216 . Bench  216  is affixed to the upper section of the roadable vehicle  50  of flying vehicle  100 . Each blade ( 212   f ,  212   r ) is typically balanced by a respective counter-weight ( 218   f ,  218   r ). 
     It should be appreciated that for a common roadable vehicle  50  having a length L V ≈4 meters, the length of a blade is about 2 meters see  FIG.  1   a   ), and thus the surface area (S) covered by the rotating rotor  110  is: 
         S =π*(vehicle length /2) 2 =π*4≈12.5 m   2 .
 
     It should be further appreciated that a surface area (S) of 100 m 2  that is covered by the twin rotating rotors (see, for example blades  310 ,  FIGS.  3   a    and  4 B) is: 
         S   TWIN =2*(π*vehicle_length 2 )=2*(π*16)≈100 m   2 ,
 
     and thereby provide enough lifting power for an efficient helicopter/gyrocopter flight. 
     It should be further appreciated that for a common roadable vehicle  50  having a length the wingspan L R  can be further expanded by parking rotating rotor  110  at the diagonal dimension L D  of roadable vehicle  50 . If the width of the vehicle is 1.8 meters, then 
         L   D =√{square root over ((4 2 )}+1.8 2 )≈4.9 m , and thereby
 
         S   DIAG =2π*19.24≈120 m   2 .
 
       FIG.  1   d    is an elevated rear perspective schematic view illustration of roadable VTOL flying vehicle  200  as shown in  FIG.  1   c   .  FIG.  1   e    illustrates roadable VTOL flying vehicle  200 , as shown in  FIG.  1   d   , wherein the rotors ( 210   f ,  210   r ) are shown in a rotational state, and wherein the surface area covered by each rotor ( 210   f ,  210   r ) is illustrated by a respective peripheral imaginary boundary outlines  219   f ,  219   r  (each peripheral imaginary boundary outlines  219  is a circle drawn by the tip of a respective blade ( 212   f ,  212   r ), similar to the imaginary circle drawn by the tip  113  of blade  112   a  of rotor  111 ). As can be seen in  FIG.  1   d   , the total surface area ( 219   f ,  219   r ) covered by the twin-rotors ( 210   f ,  210   r ) is substantially (about X8 times) larger than that covered by single rotor  110 . 
     It should be appreciated that the flight control and steering, while in air-born mode, is achieved by using any method or technique, known in the art, for controlling the air-born vehicle, using either variable or fixed pitch rotors. The flight control methods may include, without limitations, the following methods: (1) using swashplate for variable pitch rotors; (2) using rotor tilt control for fixed pitch rotors by implementing any known on the art technique of rotors tilting, including, without limitations, bi-copter scheme, wherein the rotors can be tilted separately or both; and (3) by adding additional maneuvering motors and/or any controllable aerodynamical surfaces. 
     In variations of the present disclosure, single-blade rotors  301 , such as schematically shown by way of example in  FIG.  2   a   , is used (for example, rotate about axis  304 ), or multiple-blades rotors ( 311 , 321 ) with automatic folding capability (for example, rotate about axis  315  or  324 , respectively) are used in direction  316 ,  326 , respectively, such as schematically shown by way of example in  FIGS.  2   b  and  2   c    are used, all of which rotors ( 301 , 311 , 321 ) may embed any known in the art passive or active folding mechanism. In variations of the present disclosure, such as schematically shown by way of example in  FIG.  2   c   , the whole rotor assembly may move or rotate about axis  328 . 
       FIG.  3   a    is a side view schematic illustration of another example roadable VTOL flying vehicle  300 , according to aspects of the present disclosure, wherein roadable VTOL flying vehicle  300  includes a pair of tandem, counter-rotating rotors (front rotor  310   f , and rear rotor  310   r ), wherein both of twin tandem rotors are two-blades ( 312   a ,  312   b ) rotors, and wherein each blade is near or equal to the length L V  of the roadable vehicle  50 . The example roadable VTOL flying vehicle  300 , is shown in a flight-configuration, in which configuration all folding blades ( 312   fa ,  312   fb ,  312   ra ,  312   rb ) are shown unfolded. It should be noted that the pair of rotors ( 310   f ,  310   r ) are matching and counterrotating rotors. It should be noted that blades  312   a ,  312   b  of rotors ( 310   f ,  310   r ), are foldable blades, wherein in this none limiting example, foldable blades  312   a ,  312   b  are configured as in shown by configuration  311  of  FIG.  2     a.    
       FIG.  3   b    illustrates roadable VTOL flying vehicle  300 , as shown in  FIG.  3   a   , wherein the rotors ( 310   f ,  310   r ) are shown in a rotational state, and wherein the surface area covered by each rotor ( 310   f ,  310   r ) is illustrated by a respective peripheral imaginary boundary outlines  319   f ,  319   r  (each peripheral imaginary boundary outlines  319  is a circle drawn by the tip of the respective blade ( 312   f ,  312   r ), similar to the imaginary circle drawn by the tip  113  of blade  112   a  of single rotor  111  shown in  FIG.  1     b.    
       FIG.  3   c    is a top view illustration of roadable VTOL flying vehicle  300 , wherein the rotors ( 310   f ,  310   r ) are shown in a folded state (road-configuration), and wherein the rotors ( 310   f ,  310   r ) remain withing the external boundary of roadable vehicle  50 . 
       FIG.  3   d    is a top view illustration of roadable VTOL flying vehicle shown in  FIG.  3   c   , wherein the rotors ( 310   f ,  310   r ) are shown in an unfolded state (flight-configuration), and wherein the surface area covered by each rotor ( 310   f ,  310   r ) is illustrated. 
     It should be appreciated that roadable VTOL flying vehicle  300 , may include a vehicle control sub-system  390  configured to affect folding of one or both foldable blades  312   fa,  312th,  312   ra ,  312   rb  of each rotor ( 310   f ,  310   r ), when changing from flight-configuration to road-configuration. Similarly, control sub-system  390  is configured to unfold one or both foldable blades  312   fa,  312th,  312   ra ,  312   rb  of each rotor ( 310   f ,  310   r ), when changing from road-configuration to flight-configuration. 
     It should be further appreciated that one or both foldable blades  312   fa ,  312   fb ,  312   ra ,  312   rb  of each rotor ( 310   f ,  310   r ) may fold automatically by a predesigned biassing force when changing from flight-configuration to road-configuration. The biassing may be formed by at least one spring and/or at least one piston and/or any other form of biassing force known in the art. Similarly, control sub-system  390  is configured to unfold one or both foldable blades  312   fa ,  312   fb ,  312   ra ,  312   rb  of each rotor ( 310   f ,  310   r ), when changing from road-configuration to flight-configuration. Similarly, may unfold automatically by a predesigned centrifugal force, when changing from road-configuration to flight-configuration. 
     It should be further appreciated that one or both foldable blades  312   fa ,  312   fb ,  312   ra ,  312   rb  of each rotor ( 310   f ,  310   r ) may fold/unfold automatically by any other mechanism known in the art.  FIG.  4   a    is a side view schematic illustration of another example roadable VTOL flying vehicle  202 , according to aspects of the present disclosure. Roadable VTOL flying vehicle  202  is similar to the tandem configuration of roadable VTOL flying vehicle  200 , wherein on each axle ( 215   f ,  215   r ) two coaxial rotors are mounted: front upper rotor  210   fu , activated by front upper motor  214   f , and front lower rotor  210   fd , activated by front lower motor  214   f . Similarly, rear upper rotor  210   ru , activated by rear upper motor  214   r , and rear lower rotor  210   rd , activated by rear lower motor  214   r . It should be noted that each pair coaxial rotors (upper rotor  210   u , lower rotor  210   d ), includes a pair of matching and counterrotating rotors (( 210   f u,  210   fd ) and ( 210   ru ,  210   rd )). 
     It should be appreciated that roadable VTOL flying vehicle  300 , may include a vehicle control sub-system  290  configured similar to vehicle control sub-system  390 . 
       FIG.  4   b    is a side view schematic illustration of another example roadable VTOL flying vehicle  302 , according to aspects of the present disclosure, wherein roadable VTOL flying vehicle  302  is equivalent to roadable VTOL flying vehicle  300 , and further includes an additional multiple-blades rotor  160  that provides the vehicle with an additional forward thrust. It should be appreciated that any roadable VTOL flying vehicle ( 100 , 101 , 200 , 202 , 300 , 400 , 500 , 600 , 700 , 800 , 900 ) may include an additional rotor  160  that provides the vehicle with an additional forward thrust. 
       FIG.  5   a    is a schematic illustration of an example asynchronous tandem twin-rotors ( 210   f ,  210   r ) of a computerized propulsion system  400 , according to aspects of the present disclosure, wherein each of the twin-rotors ( 210   f ,  210   r ) includes a respective motor ( 414   f ,  414   r ) coupled with an angular position sensor ( 413   f ,  413   r ). Hence, each rotor  210  is driven independently by the respective motor ( 414   f ,  414   r ). A processing unit of the computerized propulsion system  400  is configured to compute the angular position of each respective blade ( 212   f ,  212   r ). Thereby, when in road-configuration, the processing unit of the computerized propulsion system  400  is configured to park each respective blade ( 212   f ,  212   r ) such that the respective blade ( 212   f ,  212   r ) is positioned within the vertical space situated above the roadable vehicle  50  of flying vehicle  100 . 
     It should be appreciated that each motor ( 414   f ,  414   r ) can be powered by an electric power source (battery or fuel-cell), gasoline or any other fuel, or any other power source known in the art, and/or a hybrid power source combination. 
       FIG.  5   b    is a schematic illustration of an example synchronous twin-rotors ( 210   f ,  210   r ) propulsion system  500 , according to aspects of the present disclosure, wherein both rotors ( 210   f ,  210   r ) are operated by a single motor  514  that is coupled with an angular position sensor  513 . The synchronous propulsion scheme shown in  FIG.  3   b    utilizes a common axis  520  to transfer the propulsion energy from a motor  514  and split the energy between the two rotors ( 210   f ,  210   r ) using bevel gears ( 530   f ,  530   r ) or any other transmission mechanism known in the art, wherein the rotors ( 210   f ,  210   r ) rotate synchronously clock wise (CW) and counter clock wise (CCW), and wherein the relative angular offset of rotors ( 210   f ,  210   r ) is pre aligned to be able to simultaneously enter into a park position using of both blades ( 212   f ,  212   r ) using the single angular position sensor  513 . 
       FIG.  5   c    is a schematic illustration of an example synchronous twin rotors ( 210   f ,  210   r ) propulsion system  600 , wherein the twin rotors ( 210   f ,  210   r ) are operated by a hybrid motorized system  620 , including a single electric motor/generator  614  that is coupled with an angular position sensor  613  and a fuel motor  624 . 
     The fuel engine  624  may be configured to provide the main propulsion thrust to facilitate flying of the flying vehicle, wherein the electric motor  614 /generator along with angular position sensor  613  may be configured to enable rotor ( 210   f ,  210   r ) to unfold and park the blades ( 212   f ,  212   r ), when switching the flying vehicle from flight configuration to road-configuration. Electric motor/generator  614  may also be used as the fuel engine  624  starter; as secondary backup system to continue the flight should the fuel engine  624  fail; and as an alternator. 
       FIG.  5   d    is a schematic illustration of an example hybrid, synchronous or asynchronous twin rotors ( 210   f ,  210   r ) propulsion system  700 , wherein, while in road-configuration operation, the hybrid motorized system is also used to drive the wheels of the vehicle. The fuel/gasoline engine  624  may be used as an electric generator  724  for supplying electric power of the system. The fuel engine  624  may be fully separated and may also be used to drive the car wheels  52  during road-configuration operation, using any know in art hybrid engine scheme as shown, by way of example only, in  FIG.  5   d   . Propulsion system  700  may further include an electric motor/generator  724  configured to supply electric power to system  700  along with fuel engine  624 . The hybrid pair of electric motor  724  and fuel engine  624 , may be used to drive the car wheels  52  during road-configuration operation, via gear unit  60 . A power control unit  710  monitors and coordinates the electric power within system  700 , including providing electric from a rechargeable battery  720 , for example, when the fuel engine  624  is silent, and charging battery  720  when the fuel engine  624  is powered. 
     When in flying mode, fuel engine  624  may generate mechanical energy that is used drive electric motor  724  that in turn supplies electric power to power control unit  710 . Power control unit  710  then provides electric power to the motor units (such as  414   f ,  414   r ) of the respective rotors (such as  210   f ,  210   r ). Power control unit  710  provides electric power to the angular position sensor (such as  413   f ,  413   r ) and/or to any other electric unit of propulsion system  700 . 
     Reference is now made to  FIG.  6   , schematically illustrating a roadable VTOL flying vehicle  800 , wherein the twin tandem rotors ( 810   f ,  810   r ) are configured to operate as intermeshing rotors. The intermeshing tandem rotors ( 810   f ,  810   r ) are synchronized in order to avoid rotor collision. 
     Reference is now made to  FIG.  7    that schematically illustrates an example twin-rotors roadable VTOL flying vehicle  900 , according to aspects of the present disclosure, wherein a parachute container  910  is mounted above the twin tandem rotors system  200 , that is shown by way of example only. Parachute container  910  is configured to accommodate a parachute  920  that is designated to be used in emergency situations, while in flying configuration. 
     It should be appreciated that any roadable VTOL flying vehicle ( 100 , 101 , 200 , 202 , 300 , 400 , 500 , 600 , 700 , 800 , 900 ) may include a vehicle control sub-system configured similar to vehicle control sub-system  390 . 
     The invention being thus described in terms of several embodiments and examples, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art.