AU2018100560A4

AU2018100560A4 - A uniquely compact rotorcraft suitable for personal aerial vehicle applications

Info

Publication number: AU2018100560A4
Application number: AU2018100560A
Authority: AU
Inventors: Chung-How Poh; Chung-Kiak Poh
Original assignee: Poh Chung-How Dr
Current assignee: Poh Chung-How Dr
Priority date: 2017-11-01
Filing date: 2018-04-30
Publication date: 2018-05-31
Anticipated expiration: 2026-04-30

Abstract

A UNIQUELY COMPACT ROTORCRAFT SUITABLE FOR PERSONAL AERIAL VEHICLE APPLICATIONS The invention relates to a rotorcraft comprising a fuselage (10), a self-contained main 5 rotor system (12) and a pair of coaxial counter-rotating impellers (14). At least one propulsion device (126) is mounted on the main rotor system (12) to drive the main rotor system (12) into rotation to generate lift. The pair of coaxial counter-rotating impellers (14) are used to provide contributive lift and to control the yaw of the rotorcraft. The preferred technology for the wireless communication means between 10 the fuselage (10) and the self-contained main rotor system (12) is based on quantum entanglement to ensure a fundamentally secured and hack-proof communications system. Most Illustrative Diagram: FIG. 1 N) -~ N)

Description

A UNIQUELY COMPACT ROTORCRAFT SUITABLE FOR PERSONAL AERIAL VEHICLE APPLICATIONS

FIELD OF INVENTION

The present invention relates to an aircraft with rotary-wings (rotorcraft). More particularly, the present invention relates to a rotorcraft having no main gearbox.

BACKGROUND OF INVENTION A personal aerial vehicle (PAV) is an emergent aviation market that would provide on-demand aviation services. It is to provide "door-to-door" transportation solutions and among its defining characteristics are quiet, comfortable, reliable, low maintenance, ability to carry 1 to 4 passengers, maximum cruising speeds of 240 to 320 km h'1, and it can be flown by anyone with a driver’s license [1],

Helicopters are wonderful flying machines with the ability to fly forwards, backwards and sideways. This unique ability comes from the capabilities of the main rotor system, thus rendering helicopters suitable for PA Vs applications especially those involving short-haul intercity travels. However, as recent accidents have shown, the main gearbox has consistently been the Achilles’ heel of helicopters, despite the efforts to refine main gearbox architectures for decades [2], Despite industry efforts, a fundamental problem remains - a gearbox cannot be made redundant [2].

The Saunders Helicogyre was a 1920s experimental helicopter built by S.E. Saunders Limited for the British Air Ministry [3] having a rather unique main rotor system. At the end of each rotary-wing are mounted a small engine with impeller to cause rotation of the rotary-wings [3]. The gasoline tanks for the small engines are fitted inside the wings, each engine having its own tanks and feed [3], From here on, such rotary-wing configuration will be conveniently referred to as “self-contained” main rotor system. The Helicogyre serial number K1171 was completed in 1929 but ground tests were not completed and the program was cancelled on 30 December 1931 without the Helicogyre having flown [4], Furthermore, effective yaw control during hovering was not apparent.

Thus, there remains a need to develop a helicopter, or a rotorcraft in general, having a more reliable drivetrain with lower part count. Such a rotorcraft will inevitably spur the proliferation of PAVs. Furthermore, it would be a distinct advantage if the proposed concept has good scalability so that it can be applied to rotorcraft of various sizes ranging from small PAVs to large passenger helicopters for offshore applications.

SUMMARY OF INVENTION

An object of the invention is to eliminate the complex gearbox to enhance flight safety by proposing a rotorcraft having a self-contained main rotor system, and having an effective yaw control.

The rotorcraft in accordance with the present invention comprises a fuselage and a self-contained main rotor system. The main rotor system further comprises a hub and a plurality of rotor blades attached to the hub at the root of each blade. The hub is rotatably mounted on a substantially upright mast which is rigidly attached to the fuselage so that both the mast and the fuselage are in a stationary frame of reference while the main rotor system is in a rotating frame of reference with respect to the fuselage. The rotor blades can have cyclic and collective pitch controls implemented using traditional swashplate or modem swashplateless methods such as trailing-edge flaps. The main rotor system is equipped with at least a propulsion device which drives it into rotation to generate aerodynamic lift. Energy storage needed to power the propulsion device is also located on the main rotor system itself. The architecture of the rotorcraft can be greatly simplified because there is a complete absence of physical wires, fuel lines or air pressure ducts that route from the fuselage of the rotorcraft to the rotor blades. A pair of co-axial counter-rotating impellers located vertically above the main rotor system is used for effective yaw control of the rotorcraft and to provide variable contributive lift. The variable contributive lift gives a much more agile altitude control especially if fixed-pitch main rotor system is used.

Various wireless communication means such as light waves or radio waves can be used to control the propulsion device and any other active control on the main rotor system such as the trailing-edge flaps on the rotor blades. US Pat. No. 8384605 discloses a wireless communication system which includes a first communication module within a rotating frame of reference and a second communication module within a fixed frame of reference, however, such system involves a hollow shaft which is the rotor mast of a rotorcraft. The preferred wireless communication means in accordance with the present invention is based on quantum entanglement to ensure a fundamentally secured and hack-proof communication system for flight-critical controls on the self-contained main rotor system.

The rotorcraft in accordance with the present invention thus provides the full-functionality and benefits of a conventional helicopter but without the need for complex gearbox and the associated intensive maintenance, thereby providing an effective solution to the long-standing challenge facing rotorcraft relating to the reliability issue of main gearbox. In addition, the present invention greatly enhances flight safety by having plurality of independent propulsion devices on the self-contained main rotor system and that safe controlled descent during emergency can be initiated without the height-velocity constraints of conventional helicopters.

Reference will now be made to the drawings wherein like numerals refer to like elements throughout. Though discussed herein primarily in reference to personal aerial vehicles (PA Vs) or manned rotorcraft in general, it will be expressly understood that various aspects of the disclosure have broader application. In particular, various aspects of the present invention are applicable to unmanned rotorcraft. Therefore, the proceeding disclosure is provided by way of example and not by way of limitation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the present invention of a rotorcraft having a self-contained main rotor system. FIG. 2 is a side view. FIG. 3 is a top view FIG. 4 is a perspective view of an exemplary embodiment of the present invention. FIG. 5 is a perspective view of the present invention highlighting the wireless communication means.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention relates to a rotorcraft having a self-contained main rotor system involving no main gearbox. FIG. 1 shows the perspective view of the present invention of a rotorcraft comprises a fuselage (10), a self-contained main rotor system (12), and a pair of coaxial counter-rotating impellers (14) located vertically above the main rotor system (12). The fuselage (10) is spherical-like or ovoid-like in shape to minimize the effect of external winds on its yaw ability and for a cute-looking appearance to garner public interest. In accordance with the present invention, the pair of co-axial counter-rotating impellers (14) plays two vital functions - 1) to actuate yaw of the rotorcraft and 2) to control the vertical climb/descend rate of the rotorcraft.

The designations of the elements belonging to the self-contained main rotor system (12) are preceded by the numeral 12, and the same numbering methodology is used for the pair of co-axial counter-rotating impellers (14) and other assemblies having sub-elements. The self-contained main rotor system (12) further comprises a hub (122) and a plurality of rotor blades (124) attached to the hub (122) at the root of each rotor blade (124). The hub (122) is rotatably mounted on a substantially upright mast (16) which is rigidly attached to the fuselage (10). The main rotor system (12) is equipped with at least a propulsion device (126). The exemplary embodiment illustrated in FIG. 1 has two propulsion devices (126) shown enclosed in dotted box. The propulsion devices (126) drive the main rotor system (12) into rotation about the long axis V of the mast (16) to generate aerodynamic lift to cause the rotorcraft to be airborne. Examples of propulsion device (126) are turboprop, gas turbine and impeller directly driven by an electric motor / internal combustion engine. The rotor blades (124) can have cyclic and collective pitch controls implemented using traditional swashplate or modern swashplateless methods such as trailing-edge flaps (128). FIG. 2 shows the sideview of the present invention so as to give a better clarity to the arrangement of the elements. The most relevant sub-elements of the self-contained main rotor system (12) are enclosed in a dotted line region. As mentioned, the hub (122) is rotatable about the stationary mast (16) attached to the fuselage (10). In a preferred embodiment, the propulsion device (126) is electric powered and uses a fixed-pitch impeller / propeller (1262) to propel the respective rotor blade (124) forwards. Fixed-pitch impellers are used for the purpose of design simplicity and reliability compared with variable pitch system. Similar design approach is applied to the pair of co-axial counter-rotating impellers (14) wherein two fixed-pitch counter-rotating impellers (141), (142) are attached to their respective drive shafts (143), (144) and are driven by respective electric motors (145), (146). The electric motors (145), (146) are mounted onto a base-plate (147) which is rigidly connected to the mast (16). In other words, the base-plate (147) is in stationary frame of reference with respect to the fuselage (10) and this enables the pair of co-axial counter-rotating impellers (14) to effectively control the yaw of the rotorcraft in accordance with the present invention using differential torque between the two impellers (141), (142) by varying the rotational speeds of the electric motors (145), (146). The rotating axes of the pair of co-axial counter-rotating impellers (14) substantially coincide with the long axis V of the mast (16).

To perform a hover, the self-contained main rotor system (12) is spun to about 300 RPM which should provide approximately 70% of the total lift required to keep the rotorcraft airborne and the general downwash direction is as indicated by an arrow (18) in accordance with the present invention. The remaining lift required for hover comes from the pair of co-axial counter-rotating impellers (14) and the general downwash direction is as indicated by an arrow (20). To cause the rotorcraft to ascend from the hovering position, both electric motors (145), (146) will increase their rotational speeds. Likewise, to cause the rotorcraft to descend from the hovering position, both electric motors (145), (146) will decrease their rotational speeds. A higher percentage of contributive lift from the pair of co-axial counter-rotating impellers (14) will enable altitude of the rotorcraft to be controlled more precisely especially in windy conditions. Conversely, a lower percentage of the contributive lift from the pair of co-axial counter-rotating impellers (14) will lead to a more energy efficient hover but the rotorcraft may be more “floaty” in windy conditions.

In accordance with the present invention, energy storage (not shown), such as battery packs or ethanol liquid fuel, needed to power the propulsion device (126) is also located on the self-contained main rotor system (12) itself. The complete absence of physical wires, fuel lines or air pressure ducts that route from the fuselage (10) of the rotorcraft to the rotor blades (124) consequently permits simple and lightweight design of the rotorcraft. In short, the rotorcraft in the present invention provides the full-functionality and benefits of a conventional helicopter while simultaneously eliminates the need for complex gearbox that requires intensive maintenance, thereby providing an effective solution to the long-standing problem of unreliable main gearbox.

Unlike conventional main gearbox that cannot be made redundant, the present invention offers flight safety enhancement by having plurality of independent propulsion devices (126) on the self-contained main rotor system (12). In case of powertrain failure, a gearbox driven helicopter is generally said to be able to enter into autorotation mode and make a controlled descent to safety. However, in reality, autorotation can only be successfully performed if the helicopter is operated within certain height-velocity regimes when the incident occurs. On the contrary, the present invention offers significant flight safety advantages over conventional gearbox-driven main rotor systems by having at least one propulsion device resides on each rotor blade. For example, consider a scenario in which the main rotor system (12) consists of five rotor blades (124), and each rotor blade (124) having three independent propulsion devices (126). In total, the main rotor system contains 15 independent propulsion devices (126). Computer simulation results suggested that only about 9 of the propulsion devices (126) have to be working in order for the rotorcraft to make a safe controlled descent, and it is very much independent of the height or velocity of the rotorcraft. In other words, the main rotor system (12) in accordance with the present invention offers high degree of flight safety, in addition to having a drivetrain that is lighter, simpler, easier to maintain and with greater overall reliability. FIG. 3 shows the topview of the rotorcraft in the present invention. The impellers (1262) of the respective propulsion devices (126) generate thrusts in the direction indicated by an arrow (22), thus pulling the respective rotor blades (124) forwards causing them to rotate about the axis V (as indicated in FIGS. 1 and 2). As mentioned, trailing-edge flaps (128) is one of the swashplateless methods used to provide cyclic controls to the rotor blades (124). Another possible swashplateless method is the limited angle direct-drive motor (LADDM) which does not require trailing-edge flaps (128). In an exemplary embodiment in which the propulsion devices (126) are electric powered, the respective electric motors, battery packs and motor controllers can be compactly housed within the respective nacelles (1264). The advantages of placing the battery packs in the nacelles (1264) are simpler design as well as ease of maintenance and inspection as the components are strategically located, but the main disadvantage is that the centrifugal forces experienced by the battery packs are higher depending on the distance to the axis V. On the other hand, placing the battery packs closer to the axis V, e.g. within the hub (122) results in a low centrifugal force (hence mechanical stress), but would entail additional wiring and possibly an increase in ohmic loss. A way to maximize the battery capacity on the main rotor system (12) would be to place the battery packs in the hub (10) as well as to distribute them throughout the interior spaces of the rotor blades (124) and the nacelles (1264). FIG. 4 shows the perspective view of an exemplary embodiment of the present invention in which each rotor blade (124) has two propulsion devices (126) and it uses the LADDM method for blade pitch control and so no trailing-edge flaps are needed.

The communications between the fuselage and the main rotor system is preferably via wireless communication means. FIG. 5 shows the perspective view of the rotorcraft wherein the wireless communication means is implemented by having at least a communication module (24) within the fuselage (10) and at least a communication module (26) within the main rotor system (12), for example, in the hub (122), in the interior spaces of the rotor blade(s) (124) or in the nacelle(s) (1264). While a variety of wireless technologies such as magnetic, light waves or radio waves can be used in the present invention, a preferred wireless technology is based on quantum entanglement to ensure a fundamentally secured and hack-proof communications system for flight-critical controls on the main rotor system (12). The China’s quantum satellite has recently demonstrated the highly anticipated “spooky action” at a record distance of 1200 km, indicating that ultra-secure communications is now physically possible.

The foregoing description of the present invention has been presented for purpose of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and skill and knowledge of the relevant art, are within the scope of the present invention. The embodiments described hereinabove are further intended to explain best modes known of practicing the invention and to enable other skilled in the art to utilize the invention in such or other embodiments and with various modifications required by the particular application(s) or use(s) of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.

References: 1. Wikipedia (2017) Personal air vehicle. https://en.wikipedia.org/wiki/Personal air vehicle 2. T. Dubois and M. Huber (2013) Main Gearbox Remains Helicopters’ Achilles Heel. AINonline. https://www.ainonline.com/aviation-news/aviation-international-news/2013-01-01/main-gearbox-remains-helicopters-achilles-heel 3. Flight (1929) The "Helicogyre". https://www.flightglobal.com/pdfarchive/view/1929/1929%20-%200594.html 4. Wikipedia (2017) Saunders Helicogyre. https://en.wikipedia.org/wiki/Saunders Helicogyre

Claims

CLAIMS:

1. A rotorcraft comprising: a fuselage (10); and a self-contained main rotor system (12) comprising a hub (122) and a plurality of rotor blades (124) attached to the hub (122) at the root of each rotor blade (124), the hub (122) is rotatably mounted on a substantially upright mast (16) rigidly attached to the fuselage (10), the main rotor system (12) is equipped with at least a propulsion device (126) which drives it into rotation about the long axis V of the mast (16) to generate aerodynamic lift to cause the rotorcraft to be airborne is characterized in that: a pair of co-axial counter-rotating impellers (14) whose rotating axes substantially coincide with the axis V is used to provide effective yaw control of the rotorcraft; and there is a complete absence of physical wires, fuel lines or air pressure ducts that route from the fuselage (10) of the rotorcraft to the rotor blades (124).
2. A rotorcraft as claimed in Claim 1, wherein the fuselage (10) is spherical-like in shape.
3. A rotorcraft as claimed in Claim 1, wherein the fuselage (10) is ovoid-like in shape.
4. A rotorcraft as claimed in Claim 1, wherein communications between the fuselage (10) and the main rotor system (12) is implemented via wireless communication means involving at least a communication module (24) within the fuselage (10) and at least a communication module (26) within the main rotor system (12).
5. A rotorcraft as claimed in Claim 4, wherein the preferred technology for the wireless communication means is based on quantum entanglement to ensure a fundamentally secured and hack-proof communications system for flight-critical controls on the self-contained main rotor system (12).