CROSS REFERENCE TO OTHER APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63/358,048 entitled ADAPTIVE DUCT FAN WITH INDIVIDUALLY CONTROLLED SLATS filed July 01, 2022, which is incorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION

[0002] The present disclosure is related generally to aircraft, such as electrical (and other) Vertical Take-off and Landing (e)VTOL and Conventional Take-off and Landing CTOL propulsion systems and is applicable to traditional aircrafts design as well as to unmanned aerial vehicles UAV, remotely piloted aircraft systems RPAS, advanced air mobility systems AAM, regional air mobility RAM and urban air mobility UAM, civil and military uses, and other uses.

[0003] Electric-powered vertical takeoff and landing (eVTOL) aircraft have been and are being developed for manned and unmanned flight, including autonomous and piloted manned flight. eVTOL aircraft typically are propelled by a plurality of propellers, each driven by an electric or turbo-reactive engine. eVTOL aircraft may include additional propulsion components such as an electric ducted fan (EDF), a ducted fan (DF), or a double ducted fan (DDF) comprising a double air absorbing mouth directed toward the propeller.

[0004] A ducted fan is an air moving component typically comprising a propeller axially mounted within a cylindrical shroud or duct. The duct reduces losses in thrust from the tips of the propeller blades. The cross-sectional shape or profile of the duct typically is designed to advantageously affect the velocity and pressure of the airflow according to Bernoulli's principle. In various embodiments, ducted fan propulsion is used in an eVTOL aircraft, in which the propeller is driven by an electric motor.

[0005] In a typical ducted fan propulsion system, the cross-sectional shape or profile of the duct is static. As a result, the designer must choose between a profile or shape that works sufficiently well for a range of operating conditions and requirements, such as the high thrust required for takeoff and landing, in the case of an eVTOL aircraft, as compared to more steady state (e.g., hover) or cruising conditions.

[0006] Known ducted fan propulsion devices suffer from several disadvantages. First, the static inlet geometry of these propulsion devices typically limits the power achieved, as the power provided is generally directly proportional to the mass of the processed air. Second, to operate these known propulsion devices under conditions of low atmospheric pressure, it is necessary to increase the frequency of the propulsion system speed to process the required amount of air, which leads to an exponential decrease in system efficiency overall. Third, due to the fixed structure (i.e., the fan duct) used in known propulsion devices, the propulsion device is incapable of adapting to variable atmospheric conditions. Fourth, in the case of known turbo-fan devices, which feature a fixed duct structure, the turbo-fan device works inefficiently on takeoff and during ascent to cruise altitude (fuel consumed per unit of thrust), resulting in increased fuel consumption.

[0007] Traditional VTOL and CTOL propulsion systems include (a) open propeller; (b) rotors; (c) ducted fans. Current thruster solutions may suffer from various disadvantages, such as low efficiency related to its weight, diameters or scalability, power consumption and the challenge of controllability between transition mode, climb or hover and cruise flight regime.

[0008] A ducted fan is an air moving component typically comprising a propeller axially mounted within a cylindrical shroud or duct. The duct reduces losses in thrust from the tips of the propeller blades. The cross-sectional shape or profile of the duct typically is designed to advantageously affect the velocity and pressure of the airflow according to Bernoulli's principle. Ducted fan propulsion may be used in an (e)VTOL aircraft, in which the propeller is driven by an electric motor. In a typical ducted fan propulsion system, the cross-sectional shape or profile of the duct is static. As a result, the designer must choose between a profile or shape that works sufficiently well for a range of operating conditions and requirements, such as the high thrust required for takeoff and landing, in the case of an (e)VTOL aircraft, as compared to more steady state (e.g., hover) or cruising conditions.

[0009] Known ducted fan propulsion devices suffer from several disadvantages. First, this static inlet geometry of these propulsion devices typically limits the power achieved, as the power provided is generally directly proportional to the mass of the processed air.

Second, to operate these known propulsion devices under conditions of low atmospheric pressure, it is necessary to increase the frequency of the propulsion system speed to process the required amount of air, which leads to an exponential decrease in system efficiency overall. Third, due to the fixed structure (i.e., the fan duct) used in known propulsion devices, the propulsion device is incapable of adapting to variable atmospheric conditions. Fourth, in the case of known turbo-fan devices, which feature a fixed duct structure, the turbo-fan device works inefficiently on takeoff and during ascent to cruise altitude (fuel consumed per unit of thrust), resulting in increased fuel consumption.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Various embodiments of the invention are disclosed in the following detailed description and the accompanying drawings.

[0011] Figure 1 shows an embodiment of an ADF 100 as disclosed herein.

[0012] Figure 2 shows the ADF of Figure 1 in the second position or deployed

(optimized for takeoff/landing/hover mode, in various embodiments).

[0013] Figure 3 shows a partially cut away side view of the ADF of Figures 1 and 2 with the primary slats [2] in the retracted position.

[0014] Figure 4 shows a partially cut away side view of the ADF of Figures 1 and 2 with the primary slats [2] in deployed position.

[0015] Figure 5 shows the retracted position a bisectional cut away side view of the ADF of Figures 1 through 4.

[0016] Figure 6 shows the deployed position of the ADF of Figure 5.

[0017] Figure 7 shows the retracted position of the ADF of Figure 6.

[0018] Figure 8 shows the deployed or second position of the ADF with all movement elements [4] [11] and [21] opened and extended up as well as the secondary slats [6,7]-

[0019] Figure 9 shows sectional detail view of the linkages and structures of the retracted ADF and support the primary slats [2] and secondary slat [6],

[0020] Figure 10 shows another section detail view of the linkages and structures of the deployed ADF and support the primary slats [2] and secondary slat [6],

[0021] Figure 11 shows another segment detail view of the linkages and structures of the deployed ADF with opened the primary slats [2] and secondary slats [6 and 7],

[0022] Figure 12 shows the same view detail represented in Figure 11.

[0023] Figure 13 shows the section of retracted ADF with the main primarily slat [2] implemented with the deflated and constrained air boot [22],

[0024] Figure 14 shows the section of extended/deployed ADF with the main primarily slat [2] implemented with the inflated and extended air boot [22],

[0025] Figure 15 shows the side view and section of retracted ADF where the primary slats [2] are retracted forming the aerodynamic nacelle and the fixed height of the chord.

[0026] Figure 16 shows the side view and section of retracted ADF where the primary slats [2] are retracted forming the aerodynamic nacelle and the fixed height of the chord.

[0027] Figure 17 shows the side view and section of ADF demonstrating the ability of individually and autonomically controlled segmentation of intake primary slats [2],

[0028] Figure 18 shows the side view and section of ADF demonstrating the ability of individually and autonomically controlled segmentation of intake primary slats [2],

[0029] Figure 19 shows an embodiment of an ADF as disclosed herein in a deployed mode or position.

[0030] Figure 20 shows the ADF of Figure 19 in a transition mode or configuration.

[0031] Figure 21 shows the ADF of Figures 19 and 20 in a fully retracted position.

[0032] Figure 22 provides a glossary of item numbers (reference numerals) and corresponding component names/descriptions for Figures 1 through 21 and the respective quantity of each item included in some embodiments of an ADF as disclosed herein.

DETAILED DESCRIPTION

[0033] The invention can be implemented in numerous ways, including as a process; an apparatus; a system; a composition of matter; a computer program product embodied on a computer readable storage medium; and/or a processor, such as a processor configured to execute instructions stored on and/or provided by a memory coupled to the processor. In this specification, these implementations, or any other form that the invention may take, may be referred to as techniques. In general, the order of the steps of disclosed processes may be altered within the scope of the invention. Unless stated otherwise, a component such as a processor or a memory described as being configured to perform a task may be implemented as a general component that is temporarily configured to perform the task at a given time or a specific component that is manufactured to perform the task. As used herein, the term ‘processor’ refers to one or more devices, circuits, and/or processing cores configured to process data, such as computer program instructions.

[0034] A detailed description of one or more embodiments of the invention is provided below along with accompanying figures that illustrate the principles of the invention. The invention is described in connection with such embodiments, but the invention is not limited to any embodiment. The scope of the invention is limited only by the claims and the invention encompasses numerous alternatives, modifications and equivalents. Numerous specific details are set forth in the following description in order to provide a thorough understanding of the invention. These details are provided for the purpose of example and the invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the invention is not unnecessarily obscured.

[0035] An adaptive ducted fan (ADF) propulsion system is disclosed. In various embodiments, an ADF as disclosed herein includes a variable-geometry inlet (e.g., bell mouth). The inlet may include a plurality of primary slats each adjacent pair of slats having a secondary slat interleaved between them. In a first position (geometry) of the ADF, the primary slats are in a non-extended (or retracted) state and define a first diameter and shape of the inlet.

[0036] In retracted mode, in some embodiments, the primary slats conceal (e.g., substantially enclose) the secondary slats and are substantially adjacent to one another. In some embodiments, in the first position the secondary slat is at least partly enclosed in an inner cavity of each adjacent primary slat. In deployed mode (i.e., the bell mouth opened) of the ADF, in various embodiments, the primary slats are extended upward (i.e., opposite the direction of air flow into the inlet) and outward, to define a substantially larger diameter inlet cross-section of aerodynamic shape to facilitate high volume of air flow through the duct fan. For example, in some embodiments, the inlet diameter increases from about 6.5ft to about 8.50ft meters, resulting in an increase of more than 50% in cross-sectional area and therefore the air flow absorption into the duct.

[0037] In some embodiments, as the primary slats are extended upward/outward, the secondary slat between each pair of primary slats likewise extends upward and outward/back and slides at least partly out from within the respective cavities of the adjacent primary slats to fill a gap between primary slats that would otherwise be present when the primary slats are in the second position.

[0038] Together, in the deployed (extended) position, the primary slats and interleaved secondary slats define a bell mouth shaped inlet having a wider cross sectional inlet area than the inlet defined by the primary slats alone when in the first position and a bell mouth shape that is optimized to move a greater mass of air at a higher velocity through the bell mouth (deployed) and into and through the ADF, resulting in greater thrust at fixed power consumption as well as stabile revelation per minute RPM - approximately + 80% at than would be achieved if the ADF inlet remained in the first position (retracted).

[0039] In various embodiments, the ADF annular slats comprising the inlet section can be operated independently of each other, improving the flight dynamics during the transition from hover to cruise minimizes the drag and maximizes the controllability. For example, in some embodiments, in transition from vertical to horizontal flight, an ADF engine as disclose herein tilts forward, and as the engine tilts forward the lower slats remain (more) fully extended at first, while the upper slats begin to retract, which reduces drag as the aircraft transitions to forward flight. In some embodiments, the independently operable slats may be retracted/deployed in unison, i.e., each retracting or extending to the same extent at the same time, depending on weather and/or other conditions, such as different atmospheric pressure. A combination of variable retraction/extension and/or non-uniform retraction/extension may be employed, e.g., based on conditions or context, to maximize the flight control and efficiency.

[0040] In various embodiments, an ADF as disclosed herein may be integrated into an (e)VTOL aircraft fully satisfying the VTOL mission: very efficiently hover, stable controllability transition and the high speed and minimum drag in cruise flight.

[0041] Various embodiments of an ADF as disclosed herein are now described with reference to the accompanying figures.

[0042] Figure 1 shows an embodiment of an ADF 100 as disclosed herein. In the retracted position (optimized, in some embodiments, for cruise flight, e.g., in a forward flight mode) shown in Figure 1, the ADF nacelle 100, comprising the nacelle body 104 [1] and retracted primary slats 102 [2] is oriented substantially horizontally, the air inlet (retracted bell mouth) at top and air outlet/exhaust (nozzle) at bottom, such that in operation air would flow in from the top, be pulled through the ADF by the central and axially mounted fan propeller and then exit out the bottom (outlet/nozzle) of the ADF as shown. In the example and state shown, the primary slats 102 [2] defining the inlet of the ADF are in the first position or retracted. While the ADF is shown in a horizontal orientation in Figure 1, in use the engine in the retracted mode shown may be rotated to a vertical orientation, such that air would flow into the front of the ADF and out the back. The secondary slats (not visible in Fig 1, see Fig 2 below, e.g.) are concealed in cavities of the adjacent primary slats [2], In the first position, as shown, the inlet defined by the primary slats [2] and the lower duct (sometimes referred to as “nacelle body”) [1] define the shape of the duct/path through which air flows through the ADF in the first position or retracted mode.

[0043] Also shown in Fig 1 are the floating covers [11], which in this example cover and protect the linkage by which the secondary slats are deployed and secured in the second position, as described below. In addition, the fan (propeller) [12] and associated inlet hub [12a] and exhaust cone [12b] are shown.

[0044] Figure 2 shows the ADF of Figure 1 in the second position or deployed (optimized for takeoff/landing/hover mode, in various embodiments). In the second position or deployed ADF as shown in Figure 2, the primary slats 102 [2] have been extended upward (slightly) and outward from the lower duct 104 [1], As the primary slats 102 [2] moved upward and outward, the adjacent edges of the respective adjacent pairs of primary slats 102 [2] moved apart, with the combined motion causing the secondary slats 106 [6 left and 7 right] to move upward and outward by operation of the linkage protected by the floating covers [11] while sliding up and out at least partly from within the cavities in the primary slats 102 [2] resulting in the secondary slats 106 [6,7] being positioned to fill gaps that otherwise would be present between the primary slats 102 [2] when in the second position or deployed position, as shown in Figure 2. In the deploy ed/second position, the path for air flow through the ADF is defined by combined inner surfaces of the primary slats 102 [2] and second slats 106 [6,7] in the position as shown and the inner surface of the lower duct 104 [1].

[0045] Figure 3 shows a partially cut away side view of the ADF of Figures 1 and 2 with the primary slats [2] in the retracted position. In the view shown, the radial structure element [10] is shown positioned in the middle of ADF body. The annular structure element [10] is responsive to supply the rigid frame for all ADF mechanisms as well as electromechanical, hydraulic, and/or pneumatic linear actuators [4] Fig 6,7. Also we see structure hub [13] (partly obscured), the radial structure bars [14] and the motor of any type [15], such as an electric motor.

[0046] Figure 4 shows a partially cut away side view of the ADF of Figures 1 and 2 with the primary slats [2] in deployed position. In the position shown, the primary slats [2] and second slats [6,7] have been extended upward and tilted away from the central axis of the ADF, defining a wider diameter opening relative to the retracted or first position. The linkages and actuators used to extend and support the primary slats [2] and secondary slats

[6.7] in the second position, as shown, are visible in Figure 4,5 and are described more fully below.

[0047] Figure 5 shows the retracted position a bisectional cut away side view of the ADF of Figures 1 through 4. In the view shown, the central and axially mounted electric motor [15] configured to drive the fan/propeller [12] is visible. Electrical power is provided via one of radial structure bar [14], which in various embodiments also may serve to mount the ADF to an (e)VTOL or other aircraft.

[0048] Detailed drawings A, B (1 :2) of Figure 5 show the secondary left slat [6] moved by electric or hydraulic actuator [4] and the mounting of shafts [16] connected to road of linear guidance [5] rigidly handled by the curved guidance tracks [8,9] all these fixed on the ADF bottom with the radial structure bars [14],

[0049] Figure 6 shows the deployed position of the ADF of Figure 5. As shown, the opened upward actuation of electrical/hydraulic road actuator [4], rigidly handled by the opened upward curved guidance tracks [8,9] and guided by the flat linear guidance [5], has resulted in the primary slats [2] and secondary slats [6, 7] being deployed (extended up and back) to the positions as shown.

[0050] Figure 7 shows the retracted position of the ADF of Figure 6. Where all the guidance that form the movement mechanism as [4] [5] and [8,9] are retracted or closed in and the secondary slats [6,7] are retracted as well.

[0051] Figure 8 shows the deployed or second position of the ADF with all movement elements [4] [11] and [21] opened and extended up as well as the secondary slats

[6.7]-

[0052] Figure 9 shows sectional detail view of the linkages and structures of the retracted ADF and support the primary slats [2] and secondary slat [6], The retracted electrical/hydraulic actuator [4] In addition to the structure is representing the radial structure element [10] also is shown the primary board [3] and the nacelle cover [11],

[0053] Figure 10 shows another section detail view of the linkages and structures of the deployed ADF and support the primary slats [2] and secondary slat [6], Also is shown the deployed electrical/hydraulic actuator element [4] In addition extended/opened curved track [21] the primary board [3] and the nacelle cover [11] and the radial structure element [10], [0054] Figure 11 shows another segment detail view of the linkages and structures of the deployed ADF with opened the primary slats [2] and secondary slats [6 and 7], Also is shown the deployed the flat linear guidance [5] the extended/opened curved track [21] the primary board [3] and the radial structure element [10] and the radial structure bars [14], [0055] Figure 12 shows the same view detail represented in Figure 11. Where the ADF is retracted with the primary slats [2] and secondary slats [6], Also is shown the retracted the flat linear guidance [5] the primary board [3] and the radial structure element [10] and the radial structure bars [14],

[0056] Figure 13 shows the section of retracted ADF with the main primarily slat [2] implemented with the deflated and constrained air boot [22], In addition the following structure elements are shown: primary board [3], the radial structure element [10] and the radial structure bars [14],

[0057] Figure 14 shows the section of extended/deployed ADF with the main primarily slat [2] implemented with the inflated and extended air boot [22], In some embodiments, air boot [22] is expanded (filled) by supplying air (or other gas) under pressure. The air boot [22], in various embodiments, may be extended, e.g., under computer control, based on sensed conditions (weather, wind, vibration, etc.) to provide increased strength or rigidity, provide a more aerodynamic cross section, absorb vibration, etc. Also shown in Figure 14 are additional structure elements: primary board [3], the radial structure element [10] and the radial structure bars [14],

[0058] Figures 15,16 show the side view and section of retracted ADF where the primary slats [2] are retracted forming the aerodynamic nacelle and the fixed height of the chord.

[0059] Figures 17,18 show the side view and section of ADF demonstrating the ability of individually and autonomically controlled segmentation of intake primary slats [2], Also is shown how the height of the duct is increasing and adjusted as needed. This segmentation movement is designed for increasing the controllability of ADF in the transition mode from the hover to cruise flight.

[0060] Figure 19 shows an embodiment of an ADF as disclosed herein in a deployed mode or position - e.g., during hover or vertical takeoff and landing. When the power consumption is greater the ADF is deployed forming the bell mouth effect that gives a very substantial area increase of air absorption into the duct which increasing thrust up to 80% at fixed power.

[0061] Figure 20 shows the ADF of Figure 19 in a transition mode or configuration - e.g., while transition (tilting) from hover (vertical flight) to cruise (forward flight) and vice versa. When the thruster (ADF) is tilting between hover and cruise and vice versa, the slats are autonomously segmenting the intake slats for better distribution of air flow which is reducing the drag and increasing the controllability. In various embodiments, the slats [2] are operated under individually (or in sets) under computer control to minimize drag. The extent of extension/retraction for any given slat [2] may be determined and controlled based on one or more of the angle of tilt, speed through the air, vibration or other sensed condition, atmospheric conditions, etc. For example, simulation, wind tunnel or other lab testing, and/or field testing may be performed to determine for each set of conditions an optimal set of positions/values for each slat [2] on each engine. In operation, the learned/determined profiles may be used to transition the slats [2] individually each through a sequence of positions, e.g., to minimize drag and/or vibration, at each stage of a transition between vertical and forward flight or vice versa.

[0062] Figure 21 shows the ADF of Figures 19 and 20 in a fully retracted position - in which the slats [2] have been fully closed/retracted for high cruise speed and lower drag. During the cruise the sharp section of the ADF hull section minimizes drag, in various embodiments, improving the speed efficiency and the range of flight.

[0063] Figure 22 provides a glossary of item numbers (reference numerals) and corresponding component names/descriptions for Figures 1 through 21 and the respective quantity of each item included in some embodiments of an ADF as disclosed herein.

[0064] While the specific mechanisms shown in Figures 1 through 22 are used in various embodiments to provide an ADF with a transformable bell mouth as disclosed herein, in other embodiments other structures, linkages, actuators, and other mechanisms may be used to vary the size and shape of an ADF air inlet (e.g., bell mouth) section to admit greater air mass to achieve higher airflow and/or thrust, as disclosed herein.

[0065] In various embodiments, an ADF with a transformable bell mouth as disclosed herein may be integrated into an aircraft or other system, such as the aircraft described in International Patent Application Number PCT/US2020/050507, filed on September 11, 2020, and claiming priority to U.S. provisional application no. 62/898,741, filed on September 11, 2019, entitled “Adaptive Ducted Fan Propulsion System”, which was published on March 18, 2021 under International Publication No. WO 2021/050952 Al, the entire contents of which are incorporated herein by reference for all purposes.

[0066] The following are disclosed, in various embodiments:

1. A cavity tube that serves as a structure nacelle body of ADF design.

2. An annular convertible and adaptable intake design comprising several primary and secondary slats that form the ADF inlet.

3. The adjustable and adaptable intake of ADF obtained by using actuators, such as linear motors or other actuators, and the curved and flat tracks that are hidden inside the duct cavity.

4. The 3-way automated adjustment regimes: retracted, transition and deployed movement of the intake section of the ADF.

5. The 20% + adjustment of the height increase of the ADF body in deployed regime process.

6. The automated individual controlled segmentation of the inlet or intake slats of the ADF in transition mode.

7. The inflatable air boots as a component part of intake or inlet adjustable slats of ADF.

8. The ADF chord split by 40% for slats or adaptive intake section and 60% for the bottom part of the resistance and general structure of the duct.

[0067] An adaptive duct fan (ADF) with a convertible intake section mechanism that forms a controlled bell mouth effect to absorb the maximum amount of air in the duct with minimum loss, drag, and/or vibration has been disclosed.

[0068] Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, the invention is not limited to the details provided.

There are many alternative ways of implementing the invention. The disclosed embodiments are illustrative and not restrictive.