Exhaust area control of thruster trailing edge

Abstract

A propulsion system is described that includes a propulsor and an exhaust area control mechanism connected to an outlet of the propulsor and configured to vary the area through which air exits the propulsion system.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 155,968, filed March 3, 2021, U.S. Provisional Patent Application No. 63 / 156,063, filed March 3, 2021, U.S. Provisional Patent Application No. 63 / 156,067, filed March 3, 2021, and U.S. Provisional Patent Application No. 63 / 156,076, filed March 3, 2021, each of which is incorporated by reference in its entirety herein.

[0002] The present disclosure relates generally to a ducted transfer propulsion vehicle having a variable exhaust outlet area. [Background technology]

[0003] Conventional thrusters have circular or other circular cross sections at both the inlet and outlet ends. Although continuity throughout the circular shape may allow for smooth airflow through the thruster, having a circular cross section outlet limits how the outlet area can be handled. Some conventional examples with circular outlet cross sections use a sliding plate to control the outlet area of ​​the thruster. However, the circular cross section of the outlet complicates placement of the sliding plate along the circular outlet and control of the sliding plate. Summary of the Invention

[0004] A propulsion fan system is disclosed. In one embodiment, the propulsion fan system includes an exhaust control system and a propulsion fan. The exhaust control system is coupled to the propulsion fan and configured to vary an exhaust area of ​​the propulsion fan system. By varying the exhaust area, thrust magnitude and / or thrust direction can be adjusted.

[0005] In one embodiment, the exhaust control system includes a first end, a second end, and an exhaust area control mechanism. The first end is connected to an outlet of a propulsor fan configured to generate thrust. The first end has a first cross-sectional shape that substantially matches a cross-sectional shape of the outlet of the propulsor fan. However, the second end of the exhaust control system has a cross-sectional shape that is different from the first cross-sectional shape. The cross-sectional shape of the second end of the exhaust control system reduces the complexity of an exhaust area control mechanism configured to vary an area of ​​the second end of the exhaust control system.

[0006] In one embodiment, the exhaust control system is connected to the propulsion fan and has a variable length, and an exhaust area control mechanism disposed at an end of the exhaust control system that connects to the propulsion fan is configured to vary the length of the exhaust control system, such that as the length of the exhaust control system changes, the exhaust area of ​​the propulsion fan changes. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view of a propulsion fan according to one embodiment. [Figure 2A] FIG. 2A is a first exploded view of a propulsion fan according to one embodiment. [Figure 2B] FIG. 2B is a second exploded view of a propulsion fan according to one embodiment. [Figure 3A] FIG. 3A illustrates a perspective view of a duct lip of a propulsion fan according to one embodiment. [Figure 3B] FIG. 3B illustrates a front view of a propulsion fan duct lip in accordance with one embodiment. [Figure 3C] FIG. 3C illustrates a side view of a propulsion fan duct lip in accordance with one embodiment. [Figure 3D] FIG. 3D illustrates a cross-sectional view of a propulsion fan duct lip in accordance with one embodiment. [Figure 4A] FIG. 4A illustrates a perspective view of a propulsion fan nosecone cross section, according to one embodiment. [Figure 4B]FIG. 4B illustrates a front view of a nosecone cross-section of a propulsion fan, according to one embodiment. [Figure 4C] FIG. 4C illustrates a cross-sectional view of a propulsion fan nosecone cross-section, according to one embodiment. [Figure 4D] FIG. 4D illustrates a perspective view of a propulsion fan nosecone cross section, according to one embodiment. [Figure 5A] FIG. 5A illustrates a front view of a propulsion fan hub in accordance with one embodiment. [Figure 5B] FIG. 5B illustrates a side view of a propulsion fan hub in accordance with one embodiment. [Figure 6A] FIG. 6A illustrates a perspective view of a fan blade of a propulsion fan according to one embodiment. [Figure 6B] FIG. 6B illustrates a front view of a fan blade of a propulsion fan according to one embodiment. [Figure 7A] FIG. 7A shows a perspective view of a vane included in the fan blade shown in FIGS. 6A and 6B, according to one embodiment. [Figure 7B] FIG. 7B illustrates a front view of a vane included in the fan blade shown in FIGS. 6A and 6B, according to one embodiment. [Figure 7C] FIG. 7C illustrates a side view of a vane included in the fan blade shown in FIGS. 6A and 6B, according to one embodiment. [Figure 7D] FIG. 7D illustrates a top view of a vane included in the fan blade shown in FIGS. 6A and 6B, according to one embodiment. [Figure 8A] FIG. 8A illustrates a perspective view of a retaining ring of a propulsion fan according to one embodiment. [Figure 8B] FIG. 8B illustrates a front view of a propulsion fan retaining ring in accordance with one embodiment. [Figure 8C] FIG. 8C illustrates a side view of a propulsion fan retaining ring in accordance with one embodiment. [Figure 9A] FIG. 9A illustrates a perspective view of a propulsion fan tension ring in accordance with one embodiment. [Figure 9B] FIG. 9B illustrates a side view of a propulsion fan tension ring in accordance with one embodiment. [Figure 10A] FIG. 10A illustrates a perspective view of a propulsion fan inner duct body housing according to one embodiment. [Figure 10B] FIG. 10B illustrates a front view of the propulsion fan inner duct body housing in accordance with one embodiment. [Figure 10C] FIG. 10C illustrates a side view of the propulsion fan inner duct body housing in accordance with one embodiment. [Figure 11A] FIG. 11A illustrates a perspective view of a stator of a propulsion fan according to one embodiment. [Figure 11B] FIG. 11B illustrates a front view of a stator of a propulsion fan according to one embodiment. [Figure 11C] FIG. 11C illustrates a side view of a stator of a propulsion fan according to one embodiment. [Figure 11D] FIG. 11D illustrates a cross-sectional view of a propulsion fan stator according to one embodiment. [Figure 12A] FIG. 12A illustrates a perspective view of a tail cone of a propulsion fan according to one embodiment. [Figure 12B] FIG. 12B illustrates a front view of a tail cone of a propulsion fan in accordance with one embodiment. [Figure 12C] FIG. 12C illustrates a side view of a tail cone of a propulsion fan in accordance with one embodiment. [Figure 12D] FIG. 12D illustrates a cross-sectional view of a tail cone of a propulsion fan in accordance with one embodiment. [Figure 13A] FIG. 13A illustrates a perspective view of a peripheral drive system for a propulsion fan according to one embodiment. [Figure 13B] FIG. 13B illustrates a front view of a peripheral drive system for a propulsion fan according to one embodiment. [Figure 13C] FIG. 13C illustrates a side view of a peripheral drive system for a propulsion fan according to one embodiment. [Figure 14] FIG. 14 shows a peripheral drive system for a propulsion fan according to another embodiment. [Figure 15A] FIG. 15A illustrates a front view of an array of propulsion fans according to one embodiment. [Figure 15B]FIG. 15B illustrates a perspective view of an array of propulsion fans according to one embodiment. [Figure 16] FIG. 16 illustrates an exemplary application of a propulsion fan arrangement in accordance with one embodiment. [Figure 17A] FIG. 17A shows a front view of a hovering drone including a propulsion fan array, according to one embodiment. [Figure 17B] FIG. 17B shows a side view of a hovering drone including a propulsion fan array, according to one embodiment. [Figure 17C] FIG. 17C illustrates a top view of a hovering drone including a propulsion fan array, according to one embodiment. [Figure 18A] FIG. 18A shows a front view of a cine drone including a propulsion fan array, according to one embodiment. [Figure 18B] FIG. 18B shows a side view of a cine drone including a thruster fan array, according to one embodiment. [Figure 18C] FIG. 18C illustrates a top view of a cine drone including a thruster fan array, according to one embodiment. [Figure 19A] FIG. 19A illustrates a front view of a transport vehicle including a propulsion fan array, according to one embodiment. [Figure 19B] FIG. 19B illustrates a side view of a transport vehicle including a propulsion fan array, according to one embodiment. [Figure 19C] FIG. 19C illustrates a top view of a transport vehicle including a propulsion fan array, according to one embodiment. [Figure 20A] FIG. 20A illustrates a front view of a vertical take-off and landing (VTOL) aircraft including a propulsion fan array according to one embodiment. [Figure 20B] FIG. 20B illustrates a side view of a vertical take-off and landing (VTOL) aircraft including a propulsion fan array in accordance with one embodiment. [Figure 20C] FIG. 20C illustrates a top view of a vertical take-off and landing (VTOL) aircraft including a propulsion fan array in accordance with one embodiment. [Figure 21A] FIG. 21A illustrates a front view of a delivery drone including a propulsion fan array, according to one embodiment. [Figure 21B] FIG. 21B illustrates a side view of a delivery drone including a propulsion fan array, according to one embodiment. [Figure 21C] FIG. 21C illustrates a top view of a delivery drone including a propulsion fan array, according to one embodiment. [Figure 22] FIG. 22 illustrates a first perspective view of a propulsion fan system having an exhaust control system according to a first embodiment. [Diagram 23] FIG. 23 illustrates a second perspective view of the propulsion fan system having an exhaust control system according to the first embodiment. [Figure 24] FIG. 24 illustrates a cross-sectional view of a propulsion fan system having an exhaust control system according to a first embodiment. [Figure 25A] FIG. 25A shows different states of the exhaust control system according to the first embodiment. [Figure 25B] FIG. 25B illustrates different states of the exhaust control system according to the first embodiment. [Figure 25C] FIG. 25C illustrates different states of the exhaust control system according to the first embodiment. [Figure 26A] FIG. 26A shows a cross-sectional view of a propulsion fan system having an exhaust control system according to a second embodiment. [Figure 26B] FIG. 26B illustrates a cross-sectional view of a propulsion fan system having an exhaust control system according to a second embodiment. [Figure 26C] FIG. 26C illustrates a cross-sectional view of a propulsion fan system having an exhaust control system according to a second embodiment. [Figure 27] FIG. 27 shows a detailed view of the exhaust control system according to the second embodiment. [Figure 28] FIG. 28 illustrates a cross-sectional view of a propulsion fan system having an exhaust control system according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The drawings and the following description illustrate specific embodiments for purposes of illustration only. Those skilled in the art will readily appreciate from the following description that alternative embodiments of the structures and methods shown herein may be used without departing from the principles described herein. Reference will now be made in detail to certain embodiments, examples of which are illustrated in the accompanying drawings. It should be noted that wherever practicable, like or similar reference numerals may be used in the figures to indicate like or similar functionality.

[0009] Propulsion fan and drive system In one embodiment, a propulsion fan and drive system is disclosed. In general, the propulsion fan and drive system is configured to generate thrust. The propulsion fan and drive system may generate thrust for a variety of applications ranging from aircraft to hand tools such as leaf blowers. However, the applications of the propulsion fan and drive system are not limited to those described herein.

[0010] FIG. 1 illustrates a perspective view of a propulsion fan 100 according to an embodiment. In general, the propulsion fan 100 includes a number of components that collectively reduce the noise emitted by the propulsion fan 100 during thrust generation. Thus, the propulsion fan 100 reduces noise pollution. For example, the propulsion fan 100 includes a tensioned fan blade including a number of fan blades. By tensioning the fan blades, the angle of the fan blades is maintained at substantially the same angle whether the propulsion fan is generating maximum thrust or is not operating (e.g., stationary). This results in reduced noise pollution and improved thrust efficiency compared to conventional propulsion fans. The propulsion fan 100 reduces noise pollution provided that the angle of the fan blades is maintained within a predetermined tolerance. For example, the propulsion fan 100 emits a noise of less than 65 dBA at 300 feet sideline / 5,000 lbf.

[0011] FIG. 2A shows a first exploded view of a propulsion fan 100 according to an embodiment, and FIG. 2B shows a second exploded view of the propulsion fan 100 according to an embodiment. The propulsion fan 100 includes a number of different components as shown in FIG. 2A and FIG. 2B. In one embodiment, the propulsion fan 100 includes a duct lip 201, a nose cone 203, a hub 205, a fan blade 209, a retaining ring 210 (shown in FIG. 8A-FIG. 8C), a tension ring 211, a motor 215, a body housing 217, a number of outer casings 213A and 213B, a stator 219, and a tail cone 221. Other embodiments of the propulsion fan 100 may include other components than those shown in FIG. 2A and FIG. 2B. In one embodiment, the duct lip 201, the outer casing 213, and a portion of the stator 219 (e.g., 219C) collectively form a circulation duct that houses the propulsion fan components, as shown in FIG. 1.

[0012] 3A, 3B, 3C, and 3D show perspective, front, side, and cross-sectional views, respectively, of a duct lip 201 of a propulsion fan 100 according to one embodiment. In one embodiment, the duct lip 201 is configured to provide an undisturbed inflow of air to the propulsion fan 100. In one embodiment, the duct lip 201 is configured to be connected to a main body housing 217. The duct lip 201 may include a number of mounting holes 223 on a rear surface of the duct lip 201, as shown in FIG. 2B. Fasteners (e.g., nuts and bolts, rivets, etc.) are placed into the mounting holes 223 to connect the duct lip 201 to a first end 1001 of the main body housing 217, as described further below.

[0013] The duct lip 201 may include a plurality of panels that collectively form the duct lip 201. For example, the duct lip 201 may include a first plurality of panels that collectively form the inner surface 309 of the duct lip 201 and a second plurality of panels that collectively form the outer surface 307 of the duct lip 201 such that the duct lip 201 has a hollow center that directs air to the fan blades 209. The first and second plurality of panels may be connected to one another via various fastening means such as fasteners (e.g., screws, nuts, bolts) or via welding. The first and second plurality of panels may be made of metals such as aluminum or titanium, or composite materials such as carbon fiber. Alternatively, the duct lip 201 may be made from a single material, for example, 3D printed.

[0014] In one embodiment, the duct lip 201 includes a first end 303 (e.g., an inlet) and a second end 305 (e.g., an outlet). The first end 303 receives air and the air exits the second end 305. As shown in FIG. 3C, the diameter of the first end 303 is smaller than the diameter of the second end 305, but may be the same as in other embodiments. The diameters of the first end 303 and the second end 305 of the duct lip 201 depend on the application of the propulsion fan 100. For example, the diameters of the first end 303 and the second end 305 of the duct lip 201 are larger for an aircraft application compared to a leaf blower application.

[0015] FIG. 3D is a cross-sectional view of the duct lip 201 along the plane A-A' shown in FIG. 3B, according to one embodiment. As described above, the duct lip 201 includes an outer surface 307 and an inner surface 309. The outer surface 307 and the inner surface 309 together extend from a first end 303 of the duct lip 201 toward a second end 305 of the duct lip 201. Air flows through the inner surface 309 of the duct lip 201. The curvature 311A ​​of the inner surface 309 of the duct lip 201 and the curvature 311B of the outer surface 307 of the duct lip 201 are designed to balance various factors such as different conditions (e.g., flight conditions such as cruise, takeoff, and landing) and Reynolds numbers. One skilled in the art can tailor the duct lip radius for a preferred pressure gradient across speed regimes and flight modes of interest.

[0016] 4A, 4B, 4C, and 4D show perspective, front, cross-sectional, and perspective views, respectively, of a nose cone 203 of a propulsion fan 100 according to one embodiment. The nose cone 203 is configured to match the behavior of the oncoming airflow and reduce aerodynamic drag. The nose cone 203 can also be configured with an impeller that directs air at a cooling air flow rate without significantly impacting broadband or tonal noise.

[0017] In one embodiment, the nosecone 203 is configured to connect to the motor 215 by a hub 205 disposed between the nosecone 203 and the motor 215. The nosecone 203 may include a number of mounting holes on a rear surface of the nosecone 203, as shown in FIG. 2B. Fasteners 207 (e.g., nuts and bolts, rivets, etc.) are placed into the mounting holes to connect the nosecone 203 to a first end of the hub 205. The fasteners 207 extend through the hub 205 and connect to the first end of the motor 215, as described further below.

[0018] In one embodiment, the nose cone 203 is conical. However, in other embodiments, the nose cone 203 can have a different shape. As shown in FIG. 4A-4D, the nose cone 203 includes an opening 403 (e.g., a hole) at a first end of the nose cone 203. As the fan blades 209 rotate, air is pulled through the opening 403 in the nose cone 203 to cool the motor 215. The secondary flow rate required to cool the internal components determines the inner diameter of the opening 403 in the nose cone 203. One skilled in the art can derive this diameter depending on the thermal requirements of different electric motors and the air required to cool them under their most restrictive conditions, typically maximum continuous operation.

[0019] FIG. 4C is a cross-sectional view of the nose cone 203 along the plane B-B′ shown in FIG. 4B, according to one embodiment. In one embodiment, the nose cone 203 is not solid, but includes a cavity. For example, in one embodiment, the nose cone 203 comprises an air passage 405. The air passage 405 extends from an opening 403 in the nose cone 203 to a number of openings 407 disposed around the circumference of a second end (e.g., back) of the nose cone 203. Air flows from the opening 403 through the air passage 405 and exits the number of openings 407 to cool the motor 215. In one embodiment, the air passage 405 is formed between an outer surface 409 of the nose cone 203 and a protrusion 411 formed in the nose cone 203, as shown in FIG. 4C and FIG. 4D.

[0020] In one embodiment, the protrusion 411 protrudes inwardly from the second end of the nosecone 203 towards the opening 403 of the nosecone 203. The protrusion 411 can have a similar shape to the nosecone 203. For example, the protrusion 411 is also cone-shaped. However, in other embodiments, the protrusion 411 can have a different shape than the nosecone 203.

[0021] Generally, the protrusion 411 has a size and shape tailored for a rate of airflow to cool the motor 215. In one embodiment, the protrusion 411 includes an air passage 413 formed therethrough through which air flows from an opening 415 in the air passage 413 to an opening 417 in the second end of the nose cone 203. In one embodiment, the center of the air passage 413 is aligned with the center of the opening 403 in the nose cone 203.

[0022] 5A and 5B show front and side views, respectively, of the hub 205 of the propulsion fan 100 according to one embodiment. The hub 205 is the central portion of the propulsion fan 100 and is disposed at the center of the fan blades 209, as described further below. The hub 205 is configured to connect to the nosecone 203, the retaining ring 210, and the motor 215, in one embodiment.

[0023] As shown in FIGS. 5A-5B, in one example, the hub 205 is cylindrical. In one embodiment, the diameter of the first end 507 of the hub 205 matches the diameter of the second end of the nose cone 203. The first end 507 (e.g., the front) of the hub 205 includes a number of mounting holes 501A-501F formed through a thickness of the hub 205. The mounting holes 501 are positioned such that when the second end of the nose cone 203 connects to the first end 507 of the hub 205, the mounting holes 501 are aligned with the mounting holes of the nose cone 203. The fasteners 207 are configured to pass through the mounting holes 501A-501F and connect to the first end (e.g., the front) of the motor 215. For example, the fasteners 207 are threaded into the threaded holes 225 of the first end of the motor 215.

[0024] In one embodiment, the hub 205 also includes a number of openings 503, such as openings 503A and 503B, that extend through a thickness of the hub 205. The number of openings 503 have a shape and size that matches (e.g., is the same as) the opening 407 in the rear surface of the nosecone 203. The openings 503 are configured to align with the opening 407 in the rear surface of the nosecone 203 when the nosecone 203 and hub 205 are joined together. Thus, air exiting the opening 407 in the nosecone 203 flows through the opening 503 in the hub 205. In one embodiment, the number of openings 503 in the hub are different sizes. For example, opening 503A is smaller than opening 503B.

[0025] In one embodiment, the hub 205 also includes an opening 505 that extends through a thickness of the hub 205. The opening 505 is located at the center of the hub 205. In one embodiment, the center of the opening 505 is configured to align with the center of the air path 413 of the nose cone 203. Thus, airflow exiting the air path 413 of the nose cone 203 flows through the opening 505 in the hub 205 to cool the motor 215.

[0026] In one embodiment, the second end 511 of the hub 205, opposite the first end 507, includes a connection mechanism 509 around an outer periphery of the second end 511 of the hub 205. The connection mechanism 509 is configured to connect the hub 205 to the retaining ring 210. In one embodiment, the connection mechanism 509 is a thread such that the hub 205 is screwed into the retaining ring 210. When the hub 205 is connected to the retaining ring 210, the retaining ring 210 surrounds the outer periphery of the hub 205. The motor 215 is configured to mate to an outer surface of the second end 511 of the hub 205.

[0027] In one embodiment, the hub 205 includes an intermediate region 513 disposed between a first end 507 and a second end 511 of the hub 205. In one embodiment, the fan blades 209 are configured to be positioned around the circumference of the intermediate region 513 while the hub 205 is positioned through the center of the fan blades 209.

[0028] 6A and 6B respectively show a perspective view and a front view of the fan blade 209 of the propulsion fan 100 according to an embodiment. As shown in FIGS. 6A-6B, the fan blade 209 includes a plurality of vanes 601. The total number of vanes 601 included in the fan blade 209 is significantly more than the number of vanes in a conventional propulsion fan having 2-5 vanes. In an embodiment, the fan blade 209 may include vanes 601 ranging from 20 to 840 vanes 601. However, any number of vanes greater than 5 may be used. In general, the total number of vanes 601 included in the fan blade 209 depends on the application. In an embodiment, the material for the vanes of the multi-blade fan also depends on the type of application of the multi-blade fan. The vanes may be made of metals such as aluminum or titanium, or composite materials such as carbon fiber.

[0029] In one embodiment, the fan blades 209 reduce overall blade noise when the fan blades 209 rotate at low tip speeds (approximately 300-450 ft / sec). As described herein, tensioned fan blades 209 allow for more vanes to achieve ultrasonic signatures and low subsonic tip speeds while still remaining within mechanical material limits. Additionally, a high number of vanes 601 raises the sonic noise to ultrasonic frequencies above the upper limit of human audibility (16,000 Hz and above for a typical adult). Additionally, the lower vane loading with a higher vane count also reduces the degree of vortex-vortex collisions that cause broadband noise.

[0030] As shown in Figures 6A and 6B, the vanes 601 are arranged to form a circular torus shape with a hollow center in which the hub 205 is located. Each vane 601 is arranged such that at least a portion of the leading edge and trailing edge of the vane 601 overlaps with an adjacent vane 601. For example, the leading edge of a vane overlaps the trailing edge of the vane to its left, and the trailing edge of a vane overlaps the leading edge of the vane to its right. The overlapping arrangement of the vanes 601 provides additional stiffness to act against the incoming airflow. This stiffness can be adjusted to account for local aerodynamic effects and to account for Reynolds number effects that may affect laminar flow attachment within and between the vanes.

[0031] Figures 7A, 7B, 7C, and 7D show perspective, front, side, and top views, respectively, of a vane 601 of the fan blade 209 shown in Figures 6A and 6B, according to one embodiment. In one embodiment, each vane 601 comprises a first fixed end 605, a second fixed end 603, and a wing 607 disposed between the first fixed end 605 and the second fixed end 603. The vanes 601 may include other features beyond those described herein in other embodiments.

[0032] In one embodiment, the first fixed end 605 is located at the tip of the vane 601. The first fixed end 605 is configured to be inserted into the tension ring 211 and secure the vane 601 to the tension ring 211 such that its tip is tensioned. By tensioning the tip of the vane 601, the pitch (e.g., angle) of the tip of the vane 601 can be substantially the same during thrust generation or while the propulsion fan 100 is stopped, thereby reducing noise pollution.

[0033] As shown in Figures 7A-7D, the first fixed end 605 is a rectangular shape with chamfered edges, although other shapes can be used for the first fixed end 605. In one embodiment, the first fixed end 605 has a width and thickness that is greater than the width and thickness of the tip of the wing 607. However, in other embodiments, the first fixed end 605 can be the same width or narrower than the tip of the wing 601. One skilled in the art can adjust the edges, chamfers, surface treatments, and bezel treatments to account for local stresses and strains due to tension.

[0034] In one embodiment, the second fixed end 603 is disposed at the root of the vane 601. The second fixed end 603 is configured to be inserted into the fixing ring 210 and fix the vane 601 to the fixing ring 210. By pulling the root of the vane 601, the pitch (e.g., angle) of the root of the vane 601 is substantially the same during thrust generation or while the propulsion fan 100 is stopped, thereby reducing noise pollution. As shown in FIG. 7A-FIG. 7D, the second fixed end 603 has multiple different surfaces (e.g., straight surfaces and curved surfaces) to increase the area of ​​contact with the fixing ring 210 so as to reduce the deflection of the vane. In one embodiment, the second fixed end 603 has a width larger than the root portion of the vane 601 and wider than the width of the first fixed end 605. However, in other embodiments, the second fixed end 603 may be the same width or narrower than the root of the vane 601.

[0035] Wing 607 is located between first fixed end 605 and second fixed end 603. In one embodiment, wing 607 has a geometric twist 609 within wing 607. Geometric twist 609 is a change in the angle of incidence of the wing measured relative to the root of wing 601. That is, geometric twist 609 causes wing 607 to have multiple different angles of incidence across the length of wing 607. For example, wing 607 can have a first angle of incidence on a first side of geometric twist 609 (e.g., below geometric twist 609 in FIGS. 7A-7C) and a second angle of incidence on a second side of geometric twist 609 (e.g., above geometric twist 609 in FIGS. 7A-7C).

[0036] As a result of the geometric twist 609, the first fixed end 605 and the second fixed end 609 are offset from one another when viewed from the top of the vane 601, as shown in Figure 7D. In one embodiment, the geometric twist 609 begins at a portion of the wing 607 closer to the root of the vane 601 than to the tip of the vane 601. The geometric twist 609 between the root chord and the tip chord can vary up to 45 degrees.

[0037] 6A and 6B, in one embodiment, the vanes 601 have second fixed ends 603 arranged parallel to one another around the circumference, thereby forming a hole in the center of the fan vane 209. As a result, the first fixed ends 605 are also arranged parallel to one another, and the wings 607 of each vane 601 overlap other wings of adjacent vanes 601 due to a geometric twist 609 in the wings 607.

[0038] 8A, 8B, and 8C show perspective, front, and side views, respectively, of a retaining ring 210 of a propulsion fan 100 according to one embodiment. In general, the retaining ring 210 is configured to connect to the fan blades 209 and hub 205 and exerts beneficial tension on the root of the vanes 601. Thus, the vanes 601 of the fan blades 209 are in tension at both the tip and root to maintain the angle of the vanes 601 during operation. The retaining ring 210 can be made of a metal, such as aluminum or titanium, or a composite material, such as carbon fiber.

[0039] The stationary ring 210 includes a first end 801 and a second end 803. In one embodiment, the first end 801 has a diameter smaller than that of the second end 803, thereby forming a conical shape. This shape adjustment is driven by the need for a primary internal flow (i.e., not a cooling flow) to the fan, and may also account for any boundary layer pressure gradients along the center body in the presence of the fan. In one embodiment, the first end 801 of the stationary ring 210 is configured to directly connect the fan blades 209 to the stationary ring 210, thereby allowing the fan blades 209 to be fixed to the stationary ring 210. The first end 801 of the stationary ring 210 includes a plurality of stationary teeth 805. In one embodiment, the stationary teeth 805 are protrusions that extend from the body of the stationary ring 210 at an angle relative to a reference perpendicular to the second end 803 of the stationary ring.

[0040] A plurality of slots 807 are formed by the stationary teeth 805. For example, the slots 807 are formed between a pair of stationary teeth including stationary tooth 805A and stationary tooth 805B. The slots 807 have a width and depth that match the dimensions of the second stationary end 603 of the fan blade 209. The slots 807 extend partially through a thickness of the stationary ring 210, for example, three-quarters of the thickness of the stationary ring 210.

[0041] In one embodiment, each of the plurality of slots 807 is configured to connect to a corresponding one of the vanes 601 in the plurality of fan vanes 209. In particular, the second fixed end 603 of each vane 601 is inserted into one of the slots 807, thereby securing the vane 601 to the retaining ring 210 via direct contact between the face of the second fixed end 603 and the retaining teeth 805 that form the slot. In one embodiment, a fastener, such as an epoxy, is also applied to the second fixed end 603 of each vane 601 to further strengthen the connection between the vane 601 and the retaining ring 210. By securing the second fixed end 603 of the vane 601 to the retaining ring 210, the root pitch of the vane 601 is maintained substantially the same during thrust generation or deactivation, thereby reducing audible noise emitted from the propulsion fan 100 because the change in pitch is perceptible to the human ear.

[0042] In one embodiment, the second end 803 of the retaining ring 210 includes a connection mechanism 809 on an inner circumference of the second end 803 of the retaining ring 210. The connection mechanism 809 is configured to connect the retaining ring 210 to the connection mechanism 509 of the hub 205, for example. In one embodiment, the connection mechanism 809 is a thread that mates with the thread of the connection mechanism 509 of the hub 205, thereby allowing the hub 205 to be screwed onto the retaining ring 210. A motor 215 is connected to the hub 205, causing the hub 205 to rotate, which in turn causes the retaining ring 210 and the fan blades 209 to rotate.

[0043] 9A and 9B show perspective and side views, respectively, of the tension ring 211 of the propulsion fan 100 according to one embodiment. The tension ring 211 is configured to connect to the fan blades 209 by being disposed around the circumference of the fan blades 209. More specifically, the tension ring 211 is configured to connect to all of the first fixed ends 605 of the fan blades 209 according to one embodiment. By fixing the first fixed ends 605 of the vanes 601 to the tension ring 211, the pitch of the tips of the vanes 601 is maintained at substantially the same value during thrust production or deactivation, thereby reducing audible noise emitted from the propulsion fan 100 since changes in pitch are perceptible to the human ear. Thus, pre-tensioning the vanes 601 with the tension ring 211 reduces inefficiencies due to tip gaps. In one embodiment, the tension ring 211 is made of a metal, such as aluminum or titanium, or a composite material, such as carbon fiber. However, in other embodiments, other materials may be used.

[0044] 9A and 9B, tension ring 211 includes a first end 903 and a second end 905. In one embodiment, first end 903 has substantially the same diameter as the diameter of second end 905. A body 909 of tension ring 211 is disposed between first end 903 and second end 905.

[0045] In one embodiment, the body 909 of the tension ring 211 includes a plurality of openings (e.g., slots) 907 that extend through the entire thickness of the tension ring 211. Each opening 907 is configured to connect to a first fixed end 605 of one of the plurality of vanes 601. Thus, there is a one-to-one relationship between each opening 907 of the tension ring 211 and the vanes 601. In one embodiment, a fastener, such as epoxy, is also applied to the first fixed end 605 of each vane 601 to further strengthen the connection between the vanes 601 and the tension ring 210.

[0046] In one embodiment, the plurality of openings 907 are formed at an angle relative to a perpendicular reference to the first end 903 or the second end 905. The angle at which the openings 907 are formed matches the pitch of the first fixed ends 605 of the vanes 601. The dimensions of the openings 907 substantially match the dimensions of the first fixed ends 605 such that when the first fixed ends 605 are inserted into the openings 907 in the tension ring 211 and the first fixed ends 605 come into direct contact with the tension ring 211, the first fixed ends 605 are secured to the tension ring 211.

[0047] 10A, 10B, and 10C show perspective, front, and side views, respectively, of an internal duct body housing 217 (hereinafter referred to as the "body housing") of the propulsion fan 100 according to one embodiment. In one embodiment, the body housing 217 is configured to house (e.g., partially surround) the components of the propulsion fan 100. For example, in one embodiment, the fan blades 209, the hub 205, the tension ring 211, the retaining ring 210, and the motor 215 are housed within the body housing 217. In other embodiments, other components of the propulsion fan 100 may be housed within the body housing 217. In one embodiment, the body housing 217 is made of a metal, such as aluminum or titanium, or a composite material, such as carbon fiber. However, other materials may be used in other embodiments.

[0048] In one embodiment, the body housing 217 is cylindrical in shape and includes a first end 1001 (e.g., inlet) and a second end 1003 (e.g., outlet). The first end 1001, in one embodiment, has a diameter greater than a diameter of the second end 1003. The first end 1001 includes a number of mounting holes 1005 formed around the circumference of the first end 1001 of the body housing 217. In one embodiment, the first end 1001 of the body housing 217 is configured to connect to the second end 305 of the duct lip 201 such that the mounting holes 223 of the duct lip 201 are aligned with the mounting holes 1005 of the body housing 217. As discussed above, the fasteners 207 can be used to secure the duct lip 201 to the first end 1001 of the duct body housing 217.

[0049] In one embodiment, the second end 1003 of the body housing 217 includes a plurality of mounting holes 1007 formed around the circumference of the second end 1003 of the body housing 217. In one embodiment, the second end 1003 of the body housing 217 is configured to connect to a first end (e.g., an inlet) of the stator 219. The mounting holes 1007 of the second end 1003 of the body housing 217 are aligned with the mounting holes of the first end of the stator 219 while the second end 1003 of the body housing 217 is connected to the first end of the stator 219. The second end 1003 of the body housing 217 can be secured to the first end of the stator 219 using fasteners (e.g., nuts, bolts, rivets).

[0050] In one embodiment, the body housing 217 comprises a plurality of intermediate portions 1009, each configured to house a different component of the propulsion fan. The plurality of intermediate portions 1009 includes a first intermediate portion 1009A extending from the first end 1001 and a second intermediate portion 1009B extending from the second end 1003. The intermediate portions 1009 of the body housing 217 are located between the first end 1001 and the second end 1003 of the body housing 217.

[0051] 10C, the first intermediate portion 1009A has a different diameter than the second intermediate portion 1009B. For example, the diameter of the first intermediate portion 1000A is larger than the diameter of the second intermediate portion 1000B. Furthermore, the first intermediate portion 1009A has a smaller diameter than the first end portion 1001, and the second intermediate portion 1009B has a smaller diameter than the second end portion 1003.

[0052] In one embodiment, the first intermediate portion 1009A is configured to accommodate the hub 205, the fan blades 209, the retaining ring 210, and the tension ring 211. The diameter of the first intermediate portion 1009A is based on the diameter of the tension ring 211 because the tension ring 211 has the largest diameter of the components accommodated in the first intermediate portion 1009A. In one embodiment, the diameter of the first intermediate portion 1009A is substantially the same as the diameter of the tension ring 211, thereby allowing the tension ring 211 to be securely fixed within the first intermediate portion 1000A, for example, by a press fit.

[0053] In one embodiment, the second intermediate portion 1009B is configured to accommodate the motor 215 and a portion of the stator 219. The length of the second intermediate portion 1009B is based on the length of the motor 215 and the length of the portion of the stator 219 accommodated in the intermediate portion. The second intermediate portion 1000B has at least the same length as the motor 215 and the portion of the stator 219 to accommodate the motor 215 and the portion of the stator 219 in the second intermediate portion 1009B. In one embodiment, the diameter of the second intermediate portion 1009B is based on the flow rate of air into and out of the stator 219. One skilled in the art can adjust this diameter to induce a favorable pressure gradient over multiple, desired design speeds to minimize fluid separation or vortex. The internal cavity of the second intermediate portion 1009B can also be adjusted to reduce noise.

[0054] 11A, 11B, 11C, and 11D respectively show a perspective view, a front view, a side view, and a cross-sectional view of a stator 219 of a propulsion fan 100 according to one embodiment. In one embodiment, the stator 219 includes a plurality of stator vanes 219A, a motor housing 219B, and a stator housing 219C. In other embodiments, the stator 219 may include components other than those shown in FIGS. 11A-11D.

[0055] In one embodiment, the motor housing 219B is cylindrical in shape and includes a first end 1101 and a second end 1103, as shown in FIG. 11D. FIG. 11D illustrates a cross-sectional view of the stator 219 along plane C-C' of FIG. 11B, according to one embodiment. As shown in FIG. 11D, the motor housing 219B includes a cavity 1105 located between the first end 1101 and the second end 1103. The cavity 1105 may extend from the first end 1101 toward the second end 1103, but does not extend all the way to the second end 1103. In one embodiment, the cavity 1105 is configured to accommodate the motor 215. That is, the motor 215 is disposed within the cavity 1105 of the motor housing 219B. Thus, the shape and size of the cavity 1105 depends on the shape and size of the motor 215. Since the motor 215 is disposed within the cavity 1105 and the motor 215 is indirectly connected to the hub 205 , the stator 219 also functions as a structural component to support the hub 205 and other components of the propulsion device 100 .

[0056] In one embodiment, the motor housing 219B includes a hole 1113 through the center of the motor housing 219B, as shown in Figures 11B and 11D. The diameter of the hole 1113 is smaller than the diameter of the motor 215 to prevent the motor 215 from falling through the hole 1113. The hole 1113 is located within the motor housing 219B to aid in heat dissipation, thereby cooling the motor 215.

[0057] 11B, the stator 219 includes a plurality of stator vanes 219A. The stator vanes 219A extend radially from the motor housing 219B. That is, the root of each vane 219A is connected to the motor housing 219B, and the vanes of the stator vanes 219 extend outwardly from the motor housing 219B. In one embodiment, each vane 219A extends away from the motor housing 219B at an angle measured with respect to a reference line that extends perpendicularly from the root point on the motor housing 219B from which the stator vane 219A extends.

[0058] In one embodiment, the stator vanes 219A conduct heat away from the motor 215. The vanes 219A are in contact with the motor housing 219B that houses the motor 215, so that air passing over the vanes 219A dissipates heat generated by the motor 215. In one embodiment, the arrangement of the vanes 219A also reduces the noise generated by the fan vanes 209 and controls the thrust generated by the propulsion fan 100. The vane count of the stator vanes 219A can be selected such that the stator harmonics cancel the fan vane 209 harmonics. In the case of an ultrasonic fan, due to the locally low Reynolds number along the vanes, one skilled in the art can understand that the fan vanes 209 may have a greater number (e.g., total amount) of vanes 601 than the stator vanes 219A for preferred acoustics. This allows the vane count to be anywhere between 50% and 200% for a particular design set of sounds.

[0059] In one embodiment, the stator housing 219C is configured to accommodate the stator vanes 219A and the motor housing 219B. That is, the stator vanes 219A are disposed within the stator housing 219C such that the stator housing 219C surrounds the outer periphery of the vanes 219A. In one embodiment, the stator housing 219C includes a first end 1107 (e.g., an inlet) and a second end 1109 (e.g., an outlet). As shown in FIG. 11C, the first end 1107 has a diameter larger than the diameter of the second end 1109. Thus, the stator housing 219C can have a conical shape. However, the stator housing 219C can have other shapes in other embodiments.

[0060] 11D, in one embodiment, the tips of the vanes 219A contact the inner surface 1111 of the stator housing 219C. In this manner, the stator vanes 219A are stationary. By having the vanes 219A contact the inner surface 1111 of the stator housing 219C, the position of each vane 219A is fixed.

[0061] 12A, 12B, 12C, and 12D show perspective, front, side, and cross-sectional views, respectively, of a tail cone 221 of the propulsion fan 100 according to one embodiment. The tail cone 221, in one embodiment, is configured to create an appropriate change in area of ​​the stator housing 219C with the air exiting the propulsion fan 100. The tail cone 221 may be made of a metal, such as aluminum or titanium, or may be made of a composite material, such as carbon fiber.

[0062] The tail cone 221 includes a first end 1201 (e.g., an inlet) and a second end 1203 (e.g., an outlet). In one embodiment, the first end 1201 has a diameter greater than the diameter of the second end 1203. In one embodiment, the diameter of the tail cone 221 varies along the length of the tail cone 221. As shown in FIG. 12C, the diameter of the tail cone 221 decreases from the first end 1201 to the second end 1203 until it reaches a midpoint 1205. From the midpoint 1205 to the second end 1203, the diameter of the tail cone 221 remains relatively constant.

[0063] In one embodiment, the first end 1201 of the tail cone 221 is configured to connect to the second end 1103 of the motor housing 219B of the stator 219. In this manner, the diameter of the first end 1201 of the tail cone 221 substantially matches the diameter of the second end 1103 of the motor housing 219B of the stator 219. In one embodiment, the first end 1201 of the tail cone 221 includes a mounting surface 1209 that connects (e.g., contacts) with the second end 1103 of the motor housing 219B. The mounting surface 1209 may be attached to the motor housing 219B using, for example, fasteners. However, in other embodiments, other attachment mechanisms may be used.

[0064] 12D, there is shown a cross-sectional view of the tail cone 221 along the plane D-D' shown in FIG. 12B. In one embodiment, the tail cone 221 includes a cavity 1207 formed over the length of the tail cone 221 starting from the first end 1201 of the tail cone to the second end 1203 of the tail cone. The rear shape of the tail cone 221 is adjusted by secondary flow exhausted from the interior of the tail cone 221 with respect to the expansion of the jet following the vane disc and / or stator.

[0065] In one embodiment, the propulsion fan 100 includes a central hub drive motor 215. That is, in one embodiment, a single motor 215 is used to drive the propulsion fan 100. An exemplary motor used in the propulsion fan 100 is an electric motor. However, in other embodiments, other types of motors, such as gas motors or jet turbines, may be used in the propulsion fan 100. In general, different motor types and sizes may be used depending on the application of the propulsion fan 100.

[0066] Multi-motor drive system As an alternative embodiment, the propulsion fan 100 may be driven by multiple motors rather than just the single motor 215 described above. Figures 13A, 13B, and 13C show perspective, front, and side views, respectively, of a peripheral multi-motor drive system for the propulsion fan 100, according to one embodiment.

[0067] Instead of a single motor 215 for thrust drive, multiple auxiliary motors 1301A, 1301B, 1301C, and 1301D are disposed within the body housing 217 and drive the fan blades 209 via a ring gear 1303. The multiple auxiliary motors 1301 may be electric motors in one embodiment, however, other types of motors may be used.

[0068] In one embodiment, the ring gear 1303 can be connected to the tension ring 211. The auxiliary motor 1301 can replace the motor 215 described above or can be used in conjunction with the motor 215. The multi-motor redundancy allows for extra fault tolerance of the propulsion fan 100 system. For example, with four auxiliary motors 1301, the loss of one auxiliary motor is unlikely to have a significant impact on the normal operation of the propulsion. Even with the loss of another motor, the remaining auxiliary motors 1301 can increase their speed beyond the limit to generate sufficient thrust.

[0069] As shown in Figures 13A-13C, the auxiliary motors 1301A-1301D are radially spread around the circumference of the propulsion device 100 instead of all being located at the propulsion device hub 205. The end of each auxiliary motor 1301 is equipped with a gear that is connected to the ring gear 1303. The radial arrangement need not be limited to equal angular spacing. For example, a fan may be driven by three motors biased towards the lower quadrant of the duct. Furthermore, instead of needing a stator 219 to support the hub 205 to support the centrally housed motor 215, the propulsion device can utilize the duct structure itself to handle the motors and their loads. This also results in less broadband noise, typically caused by flow interactions at the stator, in addition to eliminating weight and drag. In one embodiment, the auxiliary motor 1301 can operate at a higher 20,000 rpm and generate a higher specific power of 15 kW / kg compared to a heavier, lower speed motor with a specific power of 5 kW / kg. The auxiliary motors 1301 drive the ring gears 1303 in unison to eliminate gear slippage (axial and radial). This lower support pressure results in lower gear noise.

[0070] Figure 14 illustrates yet another embodiment of a peripheral drive system for a propulsion fan 100, according to another embodiment. The embodiment illustrated in Figure 14 is similar to the example illustrated in Figure 13, except that the drive system illustrated in Figure 14 omits the central drive motor 215 and relies on an auxiliary motor 1301 for thrust generation. Propulsion arrangement 15A and 15B show front and perspective views, respectively, of an array of propulsion fans according to one embodiment. In one embodiment, the propulsion fan array 1500 includes a plurality of propulsion fans 100 arranged laterally to form a row of propulsion fans. In the example shown in FIG. 15A and FIG. 15B, the propulsion fan array 1500 includes a first propulsion fan 100A, a second propulsion fan 100B, and a third propulsion fan 100C. Each of the plurality of propulsion fans 100A-100C includes a propulsion fan structure described herein. Although three propulsion fans 100 are included in the propulsion fan array 1500, the array may include any number of propulsion fans greater than two.

[0071] FIG. 16 illustrates an exemplary application of a propulsion fan array according to an embodiment. As shown in FIG. 16, the propulsion fan array 1600 includes multiple propulsion fans as described herein. In one embodiment, the propulsion fan array 1600 is incorporated into a ducted wing 1603 of an aircraft 1605. Multiple propulsion fans can be combined laterally to form the ducted wing 1603. The ducted wing 1603 can be shaped to create a passive lifting biplane to which biplane staggers, sweeps, tapers, and dihedrals can be added as needed. The total number of propulsion fans included in the array 1600 and the size of the propulsion fans depend on the aircraft conditions, such as, for example, the number of passengers aboard the aircraft, the speed conditions, and the altitude conditions of the aircraft 1605.

[0072] Combining the propulsion fans in an array opens up several control and thrust vectoring opportunities. Thrust can simply be varied between each propulsion fan 100 to induce yawing, rolling, or pitching moments. Relative spanwise pitch differences between the propulsion fans can be used to facilitate faster climbs and descents. This can be further augmented by additional control surfaces on the trailing edge.

[0073] The spanwise arrangement of ducts is suitable for incorporation along the wing or even as a biplane wing itself. The array can be arranged and extended as a biplane wing with sweeps, staggers, dihedrals and tapers to suit the needs of the system. The choice to incorporate the thruster fan array as a full biplane wing depends on the amount of thrust (negative drag) required and the relative size of the thruster fans.

[0074] Uses of propulsion fans 17A, 17B, and 17C show front, side, and top views, respectively, of a hovering drone according to one embodiment. The hovering drone 1700 includes an array of propulsion fans including a first propulsion fan 100A, a second propulsion fan 100B, and a third propulsion fan 100C. Although the hovering drone 1700 includes only three propulsion fans, the hovering drone 1700 may include additional propulsion fans or fewer propulsion fans than are shown in FIGS. 17A-17C.

[0075] The hovering drone 1700 is a quiet, electric, vertical take-off and landing (VTOL) drone that includes a thruster fan array as described herein. The hovering drone 1700 can be used in close-range areas such as urban areas. The hovering drone 1700 can have 360-degree cameras and sensors and can be used for hover flight times of, for example, greater than 15 minutes. In one example, the thruster fans 100A-100C each have a thruster fan speed of 6.4 lb / ft 2 With an increased disk load of 1f, the hovering drone 1700 can have a maximum takeoff weight of 30 pounds.

[0076] 17A, each of the propulsion fans 100A-100C includes a centrally located motor 215 that drives a hub as well as an auxiliary motor 1301, as described above. However, the hovering drone 1700 may omit the auxiliary motor 1301 and include only the centrally located motor 215, or may omit the centrally located motor 215 and include only the auxiliary motor 1301.

[0077] 18A, 18B, and 18C show front, side, and top views, respectively, of a cinema drone 1800 including a thruster fan array, according to one embodiment. In general, the cinema drone 1800 is a silent, vectored wake VTOL drone used for cinema needs. The cinema drone 1800 may be all-electric or hybrid. The cinema drone 1800 may have gimbal mounted equipment (e.g., main camera) of, for example, up to 35 pounds. The cinema drone 1800 may have secondary cameras and sensors. The cinema drone 1800 may be used for hover flight times of over 20 minutes. The cinema drone, in one embodiment, may have a maximum cruising speed of over 50 mph.

[0078] In one embodiment, the cinema drone 1800 is a biplane and has a non-staggered stagger. As shown in FIG. 18A, the cinema drone 1800 includes a first wing 1801 and a second wing 1803. Each of the first wing 1801 and the second wing 1803 includes a propulsion fan array including a plurality of propulsion fans. For example, the propulsion fan array included in the wing 1801 includes propulsion fans 100A, 100B, 100C, and 100D, and the propulsion fan array included in the wing 1803 includes propulsion fans 100E, 100F, 100G, and 100H. Thus, half of the propulsion fans are on a first side of the fuselage 1805, and the other half of the propulsion fans are on a second side of the fuselage 1805. In the example shown in Figures 18A-18C, the propulsion arrangement includes eight propulsors, although any number of propulsors may be used.

[0079] Each wing 1801, 1803 of the cinema drone 1800 shown in Figures 18A-18C has an angular sweep formed between the two wings toward the front of the fuselage 1805. In the example shown in Figures 18-18C, the wings 1801 and 1803 may have anhedral wings of 20 degrees and swept wings of 30 degrees. However, other angles are possible in other embodiments.

[0080] In one embodiment, the cinema drone 1800 shown in Figures 18A-18C has a maximum takeoff weight of 75 pounds and a target maximum payload of 30 pounds. Each propulsion fan 100 has a maximum speed of, for example, 6.0 lb / ft 2 The fuselage 1805 of the cinema drone 1800 may have a length of 5.5 ft and a width of 0.6 ft. The wingspan of the cinema drone 1800 may be, for example, 4.3 lb / ft 2 Wing loading, 17.4ft 2 With a wing area of ​​8.8 ft.

[0081] 19A, 19B, and 19C show front, side, and top views, respectively, of a transport aircraft 1900 including a propulsion fan array, according to one embodiment. Transport aircraft 1900 is an optionally manned VTOL aircraft. Transport aircraft 1900 may be hybrid or all-electric. Transport aircraft 1900 may fly a range of 20-60 nautical miles at a cruising speed of 130-250 knots, for example, at an operating altitude of 1,000-2,000 feet.

[0082] In one embodiment, the transport aircraft 1900 is a biplane with a slight negative stagger. The transport aircraft 1900 includes a first wing 1901 and a second wing 1903. An angle is formed between the two wings 1901 and 1903 such that they point forward of the fuselage 1905. In the example shown in Figures 19A-19C, the wings have a 5 degree dihedral wing and a -25 degree swept wing. However, other angles are possible in other embodiments.

[0083] In one embodiment, an array of propulsion fans is integrated into each wing 1901 and 1903. A first array of propulsion fans is integrated into the wing 1901 on a first side of the fuselage 1905, and a second array of propulsion fans is integrated into the wing 1903 on a second side of the fuselage 1905. For example, the propulsion fan array included in the wing 1901 includes propulsion fans 100A, 100B, 100C, and 100D, while the propulsion fan array included in the wing 1903 includes propulsion fans 100E, 100F, 100G, and 100H. Thus, half of the propulsion fans are on the first side of the fuselage 1905, and the other half of the propulsion fans are on the second side of the fuselage 1905. In the example shown in Figures 19A-19C, the propulsion array includes eight propulsion fans, although any number of propulsion fans can be used.

[0084] In one embodiment, the transport vehicle 1900 has, by way of example, a maximum takeoff weight of 1,000 pounds and a target maximum payload of 220 pounds. Each propulsion fan 100 has a maximum speed of, for example, 6.0 lb / ft 2 The fuselage 1905 of the transport aircraft 1900 may have a length of 9.2 feet and a width of 3.75 feet. The wingspan of the transport aircraft 1900 may be 9.4 lb / ft 2 With a wing loading of 106.3 ft 2 With a wing area of ​​28.7 ft.

[0085] 20A, 20B, and 20C show front, side, and top views, respectively, of a vertical take-off and landing (VTOL) aircraft 2000 including a propulsion fan array according to one embodiment. The VTOL aircraft 2000 is an optionally manned VTOL airplane. The VTOL aircraft 2000 may be hybrid or all-electric. The VTOL aircraft 2000 may fly a range of 20-400 nautical miles at a cruising speed of 130-250 knots at an operating altitude of 1,000-2,000 feet. In one embodiment, the VTOL aircraft 2000 is capable of hovering.

[0086] In the example shown in Figures 20A-20C, the VTOL aircraft 2000 is a biplane with a slight negative stagger. The VTOL aircraft 2000 includes a first wing 2001 and a second wing 2003. In one embodiment, an angle is formed between the two wings 2001, 2003 toward the front of the fuselage 2005. The wings 2001, 2003 may have a 5 degree dihedral wing and a -25 degree swept wing. However, other angles are possible in other embodiments.

[0087] In one embodiment, an array of propulsion fans is incorporated into each wing 2001 and 2003. A first array of propulsion fans is on a first side of the fuselage 2005 and is incorporated into the wing 2001, and a second array of propulsion fans is on a second side of the fuselage 2005 and is incorporated into the wing 2003. For example, the propulsion fan array included in the wing 2001 includes propulsion fans 100A, 100B, 100C, and 100D, whereas the propulsion fan array included in the wing 2003 includes propulsion fans 100E, 100F, 100G, and 100H. Thus, half of the propulsion fans are on the first side of the fuselage 2005 and the other half of the propulsion fans are on the second side of the fuselage 2005. In the example shown in Figures 20A-20C, the propulsion array includes eight propulsion fans, although any number of propulsion fans can be used.

[0088] The VTOL aircraft 2000 has, by way of example, a maximum takeoff weight of 5,000 pounds and a target maximum payload of 1,000 pounds (e.g., 3-4 passengers). Each thruster fan 100 has, for example, 11.0 lb / ft 2 The fuselage 2005 of the VTOL aircraft 2000 may have, for example, a length of 24.7 feet and a width of 5 feet. The wingspan of the VTOL aircraft 2000 may have, for example, a wingspan of 16.7 lb / ft 2 With a wing loading of 300ft 2 With a wing area of ​​49 ft.

[0089] 21A, 21B, and 21C show front, side, and top views, respectively, of a delivery drone 2100 including a propulsion fan array, according to one embodiment. The delivery drone 2100 can have a 360-degree camera and sensors and can be used for hover flight times of over 20 minutes. The delivery drone 2100, in one embodiment, has a maximum cruising speed of over 50 mph.

[0090] The delivery drone 2100 is an example of an electric tail sitter VTOL drone configured to deliver internal cargo. In the example shown, the delivery drone 2100 is a biplane with a non-staggered stagger. The delivery drone 2100 includes a first wing 2101 and a second wing 2103 with an angular sweep formed between the two wings, in one embodiment, toward the rear of the fuselage 2105.

[0091] In one embodiment, an array of propulsion fans is integrated into each wing 2101 and 2103. A first array of propulsion fans is integrated into the wing 2101 on a first side of the fuselage 2105, and a second array of propulsion fans is integrated into the wing 2103 on a second side of the fuselage 2105. For example, the propulsion fan array included in the wing 2101 includes propulsion fans 100A, 100B, and 100C, while the propulsion fan array included in the wing 2103 includes propulsion fans 100D, 100E, and 100F. Thus, half of the propulsion fans are on the first side of the fuselage 2105, and the other half of the propulsion fans are on the second side of the fuselage 2105. In the example shown in Figures 21A-21C, the propulsion array includes six propulsion fans, although any number of propulsion fans can be used.

[0092] In one example, the delivery drone 2100 has a maximum takeoff weight of 55 pounds and a target maximum payload of 5.5 pounds. Each thruster fan 100 can have a maximum speed of, for example, 6.0 lb / ft 2 The fuselage 2105 of the delivery drone 2100 may have a length of 6.7 feet and a width of 1.3 feet. The wingspan of the delivery drone 2100 may be, for example, 2.5 lb / ft 2 With a wing loading of 21.9 ft 2 With a wing area of ​​8.8 ft.

[0093] Free wing Since the propulsion fan 100 described herein has a higher speed capability of over 150 mph, it is desirable to provide increased propulsive efficiency either by variable blade angle or by mass flow adjustment. As mentioned above, the propulsion fan 100 includes a significantly higher number of blades than conventional propulsors. Implementing a typical variable pitch propeller mechanism may be overly cumbersome in terms of mechanical complexity.

[0094] In one embodiment, the propulsion fan arrangement as described above is incorporated into an aircraft using a free vane structure. The free vane structure may be implemented, for example, in any of the aircraft described above in Figures 17-21. A free vane is a propulsion fan that is free to rotate about its radial axis due to mass balancing forward of the aerodynamic center of each vane. That is, the fan vanes 209 are free to rotate about the vane's radial axis due to mass balancing forward of the aerodynamic center of each vane. The free vane combines an airfoil design, vane mass balance, and vane pivot axis to achieve the free vane pivot function by self-adjusting to zero pitching moment at a constant CL across all flight conditions.

[0095] The combination of the free vane structure with the propulsion fan 100 creates a passive system for varying the vane angle of attack (AoA) while maintaining constant vane loading. This can provide unique synergies for the electric motor driven propulsion fan 100 since the electric motor can operate at high efficiency over a wide range of RPMs. The electric motor can operate at higher or lower radial speeds over different inlet velocities while the vanes "float" to align the AoA and maintain the same tuned lift coefficient (CL). This feature can also be valuable in achieving low noise as a way to avoid vane stalls that result in high noise at different flight conditions and turbulence levels.

[0096] The use of free vanes provides many advantages. For example, the free vanes are pitch balanced by adding leading edge vane mass to always be at an AoA close to their L / DmaxCL (typically 0.5-1.0). This ensures that the vane AoA is always aligned to match the inflow and there is no separated flow. Additionally, being peripherally driven, mass balancing is possible in the propulsion fan 100 when the inner hub region is empty, providing a volume forward of the vanes (and not exposed to flow) for counterweights for the lightest mass balance. This allows the propulsion fan 100 to vary its RPM on the order of about 50% in different flight segments, allowing the vanes to always be close to their optimum advance ratio. The use of free vanes in combination with electric motors is particularly advantageous because, unlike turbines or IC engines, electric motors have a wide range of RPMs for high efficiency. Thus, turbines or IC engines must operate at a fixed RPM for a given power, whereas electric motors do not. This allows the thrusters to vary their RPM on the order of about 50% in different segments of flight, ensuring that the vanes are always close to their optimum advance ratio. Finally, free vanes can also help enable the integration of larger VTOLs with a wider range of AoA variations and thrust needs.

[0097] Flow Duct Control In one embodiment, the flow control mechanism is disposed at the duct lip 201. The flow control mechanism is configured to blow a jet of air at the duct lip 201. Adding air at the duct lip 201 increases the amount of lip suction that the duct lip 201 can achieve. In one embodiment, an electric motor combined with a centrifugal or axial compressor may be incorporated into the remaining duct section volume to increase the flow control blowing and / or suction at the duct lip 201. By applying electric distributed propulsion (DEP) for internal flow control blowing at the duct lip 201, static and low speed thrust augmentation can be achieved with lower power than adding additional power to the propulsor. This internal application of DEP maximizes the benefits of aircraft integration at both the propulsor fan 100 and aircraft integration levels. By applying flow control at the duct lip 201, for example, static thrust is increased by up to 40% for the same fan power.

[0098] In one embodiment, an emergency power ram air turbine with high PR and intake speed requires high jet blowing speed for flow control (i.e. jets with near sonic noise). Quiet low speed jets (~300 ft / sec) can be used and can be powered by a small internal duct electric centrifugal blower.

[0099] Lower velocity flow control jets can have a similar impact in terms of thrust augmentation for the thruster, given the much lower PR and static duct inlet velocities. The effectiveness of the flow control is a function of Vjet / Vintake. Another interesting aspect of flow control duct lip blowing is the avoidance of separation at the in-duct lip at high angles of attack (i.e., during transition). This is an important consideration for ducted eVTOLs. If the intake flow were to separate at the duct lip, it would significantly increase noise as the fan blades would be in an oscillating flow condition resulting in periodic blade loading.

[0100] By applying flow control blowing at the duct lip 201 at jet velocities of about 300 ft / sec, the duct lip suction can be increased to account for about 75% of the total static thrust. Blowing air at the duct lip 201 effectively deforms the duct lip aerodynamically to entrain additional surrounding air. With the blowing turned on, the incoming air "sees" a much larger receptacle duct lip than is desired in static conditions. Using a real receptacle duct intake would result in significant drag at cruise. Duct flow control blowing can be turned off during cruise flight, where blowing is relatively ineffective. A compact high speed centrifugal blower operates at ultrasonic vane passing frequencies to provide internal blowing. Flow control blowing is most effective at high nozzle jet velocities (optimally near the speed of sound), but applicant's nozzle jets are designed for low jet velocities to achieve low noise (jet noise varies as the tenth power of nozzle velocity). In this duct tip application, the objective is to maximize the inflow turning angle and prevent stall at the duct tip lip.

[0101] In one embodiment, the flow control duct may be applied to the duct lip 201 in any of the aircraft embodiments described herein.

[0102] Exhaust Area Control System As previously discussed, the second end 1109 of the stator housing 219C is an exhaust (e.g., outlet) for the propulsion fan 100. The exhaust, in one embodiment, is the area where air flows out of the propulsion fan 100 and into the open environment. For example, the exhaust is the cross-section defined by the second end 1109 of the stator body 219C furthest from the nosecone 203 where air flows out of the propulsion fan 100.

[0103] In one embodiment, the exhaust control system is connected to the propulsion fan 100 to vary the area of ​​the exhaust port (exhaust area) of the propulsion fan 100. The exhaust control system varies the exhaust area of ​​the propulsion fan 100 to adjust the mass flow rate, thereby adjusting the thrust magnitude and / or thrust direction of the individual propulsion fan 100. For example, increasing the exhaust area through which air exits the propulsion fan 100 increases the thrust relative to the default exhaust area thrust, while decreasing the exhaust area through which air exits the propulsion fan decreases the thrust relative to the default exhaust area thrust. Different configurations of the exhaust control system are further described below. Although the following description relates to different embodiments of exhaust control systems coupled to individual propulsion fans 100, the exhaust control system may be added to an array of propulsion fans as described above.

[0104] Fig. 22 shows a first perspective view of a propulsion fan system 2200 having an exhaust control system 2201 according to the first embodiment, and Fig. 23 shows a second perspective view of the propulsion fan system 2200 having an exhaust control system 2201 according to the first embodiment. In one embodiment, the propulsion fan system 2200 includes a propulsion fan 100 as described above and an exhaust control system 2201 connected to an exhaust port of the propulsion fan 100.

[0105] As described above, the second end 1109 of the stator 219 is the exhaust of the propulsion fan 100. The cross section of the exhaust area of ​​the propulsion fan 100 has a first shape, such as a circle. In a first embodiment of the propulsion fan system 2200, the exhaust control system 2201 is connected to the second end 110 of the stator 219 to change the shape of the cross section of the exhaust of the propulsion fan system 2200 to have a second shape different from the first shape. In one embodiment, the second shape is any shape in which it is easier to change the area of ​​the exhaust compared to changing the area of ​​the first shape. For example, the second shape is any shape with straight edges that form a closed area, such as a square, rectangle, parallelogram, or triangle. Controlling the area of ​​a circle is more complicated than controlling the area of ​​a rectangle due to the curved nature of the circle.

[0106] In a first embodiment, exhaust control system 2201 includes a transition portion 2202, a plurality of flaperons 2205, and a flaperon control mechanism (e.g., motor 2401 and rod 2403). Exhaust control system 2201 may have other components than those described herein. In one embodiment, transition portion 2202 is configured to transition an exhaust outlet shape from a first shape corresponding to an exhaust outlet of propulsion fan 100 to a second shape corresponding to an exhaust outlet of exhaust control system 2201.

[0107] In one embodiment, the transition portion 2202 includes a first end 2203 connected to the second end 1109 of the stator body 219C. The first end 2203 of the transition portion 2202 has a shape that matches the shape (e.g., a first shape) of the second end 1109 of the stator body. For example, the first end 2203 of the transition portion 2202 has a circular shape with a diameter that matches the diameter of the second end 1109 of the stator body. The second end 2204 of the transition portion 2202 is an exhaust for the propulsion fan system 2200 and has a second shape.

[0108] In some embodiments, the area of ​​the first end 2203 of the transition portion 2202 is substantially the same (e.g., within 10%) as the area of ​​the second end 2204 of the transition portion 2202 to ensure that the airflow maintains a steady flow across the transition portion 2202. To ensure a smooth, noise-free flow, the transition portion 2202 is shaped to have no internal seams or edges, or at least to reduce the number of internal seams or edges. The transition portion 2202 gradually slopes or widens from the first end 2203 having a first shape (e.g., circular cross-section) to the second end 2204 having a second shape (e.g., rectangular cross-section). The transition portion 2202 is made of the same material as the stator body 219C, which can be, for example, a metal or composite material. Thus, the transition portion 2202 provides a smooth transition for changing the exhaust area shape of the propulsion fan system 2201.

[0109] In one embodiment, an elongated duct is formed from components of the propulsion fan 100 and the exhaust control system 2201. As shown in Figures 22 and 23, the elongated duct includes a duct lip 201, outer casings 213A and 213B, a stator body 219C, and a transition section 2202.

[0110] FIG 23 illustrates a plurality of flaperons 2205 included in exhaust control system 2201. Flaperons 2205 are an example of an exhaust area control mechanism that is adjusted to vary the exhaust area of ​​propulsion fan system 2200. As shown in FIG 23, the plurality of flaperons 2205 are connected to second end 2204 of transition section 2202. In the example shown in FIG 23, the plurality of flaperons 2205 includes a total of four flaperons. However, any number of flaperons 2205 may be included in exhaust control system 2201.

[0111] In one embodiment, each flaperon 2205 is a wing having a leading edge and a trailing edge. The flaperons 2205 have a rectangular cross-section and are made, for example, of metal or composite material, but may be other cross-sectional shapes. The leading edge of each of the plurality of flaperons 2205 is connected to the second end 2204 of the transition section 2202. In one embodiment, the leading edge of each flaperon 2205 is connected to the second end 2204 of the transition section 2202 by a hinge 2405 (shown in FIG. 24 ), which allows the angle of position or state of the flaperons 2205 to change, thereby changing the exhaust area of ​​the propulsor fan system 2200. That is, the flaperons 2205 can be actuated such that as they move, the flaperons 2205 can block a portion of the exhaust area, shrinking the area, or move to a position that does not restrict the exhaust area.

[0112] Thus, in the first embodiment of the propulsor fan system 2200, air flows through the duct lip 201 into the propulsor fan 100, through the fan blades 209 (not shown), the tail cone 221, and the stator 219A, through the transition section 2202, and out the exhaust area of ​​the transition section 2202 having a second shape created by the second end of the transition section 2202. The flaperons 2205 connected to the second end 2204 of the transition section 2202 can be actuated to change the exhaust area of ​​the propulsor fan system 2200 as they move to control the magnitude of thrust and / or thrust direction.

[0113] In some embodiments, the flaperons 2205 are individually controllable such that the position of each flaperon can change independently of the other flaperons. For example, each of the flaperons 2205A, 2205B, 2205C, and 2205D can move in a different direction from one another. In other embodiments, parallel flaperons 2205 can operate together such that, for example, as the upper flaperon 2205A moves inward toward the tail cone 221, the lower flaperon 2205C moves inward toward the tail cone 221 by the same amount, and as the left flaperon 2205D moves inward toward the tail cone 221, the right flaperon 2205B moves inward toward the tail cone 221 by the same amount. In embodiments where there is an array of propulsion fans, each with an exhaust control system 2201, the flaperons 2205 of each exhaust control system 2201 can be individually controlled. In other embodiments, flaperons 2205 in the same position (eg, the upper flaperon 2205A of each thruster in an array) may be operable together.

[0114] FIG. 24 shows a cross-sectional view of the propulsion fan system 2200 along the plane A-A' shown in FIG. 22, according to one embodiment. The flaperons 2205 are shaped to smoothly continue the shape of the duct airfoil. In one embodiment, each flaperon 2205 is actuated by a flaperon control mechanism that includes a motor 2401 and a rod 2403. The motor 2401 is a torque or servo motor that either pushes the rod 2403 to extend it, thereby moving the flaperon 2205 inward toward the tail cone 221, or pulls the rod 2403 to retract it, thereby moving the flaperon 2205 outward from the tail cone 221.

[0115] In the embodiment shown, when the motor 2401 pushes the rod 2403, the flaperon 2205 rotates about the hinge 2405, causing the flaperon to tilt inward (e.g., toward the tail cone 221). When the motor 2401 pulls on the rod 2403 to retract it, the flaperon rotates about the hinge 2405, causing it to angle outward (e.g., away from the tail cone). Thus, as the flaperon 2205 moves inward, the cross-sectional area of ​​the exhaust area of ​​the propulsor fan system 2200 decreases, thereby decreasing thrust, assuming the fan blades 209 rotate at a constant RPM (rotational speed). Similarly, as the flaperon 2205 moves outward, the cross-sectional area of ​​the exhaust area of ​​the propulsor fan system 2200 increases, thereby increasing thrust, assuming the fan blades 209 rotate at a constant RPM. In this manner, power can be saved because additional power is not required to increase the speed of the fan blades 209 when generating greater thrust, which would consume more power than is required to operate the exhaust control system 2201.

[0116] Although one motor 2401 per flaperon 2205 is shown in the figure for simplicity, other embodiments of a thruster with flaperons 2205 can include at least two motors 2401 or servo motors per flaperon 2205 to ensure that the flaperons are still controllable in the event of a motor or servo failure. In some embodiments, the rod 2403 is a screw that translates forward or backward as the motor 2401 rotates, depending on the direction of rotation of the motor 2401.

[0117] In one embodiment, the motor 2401 of each flaperon 2205 is housed in a cavity (e.g., hollow space) in the stator body 219C, and the rod 2401 extends from the hollow stator body 219C into the hollow portion of the flaperon 2205 and is fixed to the end of the flaperon 2205. Note that the rod 2403 currently shown is attached to the inner edge of the flaperon 2205. In other embodiments where the rod 2403 is instead fixed to the outward edge of the flaperon 2205, the extension and contraction of the rod 2403 causes the flaperon 2205 to move in the opposite direction to that described above (e.g., extension is an outward rotation and contraction is an inward rotation).

[0118] In one embodiment, the hinge 2405 is similar to a door hinge with a pin threaded through a socket connected to the stator body 219C and a socket connected to the flaperon 2205, thereby holding the stator body 219C and the flaperon 2205 together at the hinge 2405. The hinge 2405 may be located on either the inward or outward facing edge of the flaperon 2205. Other means of rotation such as a ball and socket coupling may also be used.

[0119] The flaperons 2205 can be actuated to change the size of the exhaust area to vary thrust, and can also be actuated to change the direction of the airflow to vary lift. Figures 25A, 25B, and 25C show different positions of the flaperons 2205 according to one embodiment. For simplicity, the nose cone 203, motor housing 219B, and tail cone 221 are shown in Figures 25A-C as a single central section 2503. In Figure 25A, the upper flaperons 2205A are angled inward toward the central section 2503, and the lower flaperons 2205C are angled outward. In use cases where the thruster is horizontal, such as vertical takeoff, the position of the flaperons 2205 in Figure 25A is one where air is directed downward to increase lift.

[0120] Conversely, the position of the flaperons 2205 in Figure 25B (upper flaperon 2205A tilted outward and lower flaperon 2205C tilted inward) is such that air is pushed upward, causing a downward thrust and net moment, such as lowering and / or rolling the aircraft. The outward rotation of the flaperons 2205 is represented by α and can be up to 90 degrees, and the inward rotation is represented by β and can be up to 90 degrees.

[0121] 25C shows that both of the flaperons 2205 rotate inward at approximately their maximum angle, providing the smallest possible exhaust area for the thruster fan system 2200, and therefore the lowest thrust as the air exits the thruster fan system 2200. In one embodiment, the maximum inward angle of the flaperons is approximately 60 degrees, although other maximum inward angles may be possible.

[0122] In one embodiment, the flaperon 2205 can have an initial position of 0 degrees such that the flaperon is in the initial position when no signal is sent to the motor. As an example, the initial position of the flaperon is shown in FIG.

[0123] 26A, 26B, and 26C show cross-sectional views of a propulsor fan system 2600 according to a second embodiment. In one embodiment, the propulsor fan system 2600 includes a propulsor fan 100 and an exhaust control system 2601. In contrast to the exhaust control system 2201 according to the first embodiment, the exhaust control system 2601 of the second embodiment includes an actuatable tail cone 2609 and a control mechanism for the actuatable tail cone 2609. In the second embodiment, the actuatable tail cone 2609 is configured to change the exhaust area of ​​the propulsor fan system 2600 by changing the length of the actuatable tail cone 2609 according to the second embodiment.

[0124] In a second embodiment, an actuatable tail cone 2609 replaces the tail cone 221 described above. FIG. 27 shows a detailed view of the actuatable tail cone 2609 according to the second embodiment. The actuatable tail cone 2609 includes a first end 2701 and a second end 2703, the second end being connected to the stator 219 in a manner similar to the tail cone 221 described above. In one embodiment, the second end of the tail cone 2609 includes a plurality of concentric rings 2607, each ring 2607 including at least one end that is at least partially overlapped by another one of the concentric rings. The plurality of concentric rings 2607 may be considered an exhaust area control mechanism, as described further below. Between each pair of rings is a flexible seal that prevents air from entering the hollow portion of the tail cone 2609.

[0125] In the exemplary actuatable tail cone 2609, the plurality of concentric rings includes a first ring 2607A and a second ring 2607B. The first ring 2607A corresponds to the first end 2701 of the actuatable tail cone 2609 and has a first end that connects to the stator 219 and a second end that connects to a first end of the second ring 2607B. The second end of the first ring 2607A overlaps with a first end of the second ring 2607B such that the second end of the first ring 2607A is disposed within the second ring 2607B. As described further below, the amount of overlap between the concentric rings 2607 can be varied, thereby changing the length of the actuatable tail cone 2609 to change the exhaust area of ​​the propulsion fan system 2600.

[0126] In one embodiment, the actuatable tail cone 2609 includes an intermediate portion 2705 between the first end 2701 and the second end 2703 of the actuatable tail cone 2609, which has a diameter greater than the diameters of the first and second ends. Thus, the intermediate portion 2705 of the actuatable tail cone 2609 has a widened shape similar to the bottom half of a bowling pin. As the actuatable tail cone 2609 extends, the intermediate portion 2705, which has the largest diameter, moves toward the stator 219 into the exhaust area, thereby reducing the exhaust area and reducing thrust.

[0127] 26A, the actuatable tail cone 2609 is shown in a fully retracted state (e.g., position) according to the second embodiment. In the fully retracted state, the positions of the concentric rings 2607 are adjusted to provide a maximum amount of overlap between the concentric rings 2607. In the fully retracted state, the exhaust control system 2601 increases the exhaust area of ​​the propulsor fan system 2600 to an area corresponding to the maximum thrust of the propulsor fan system 2600. For example, thrust is increased at the most constrained design speed. The exhaust area increases as the middle portion 2705 of the actuatable tail cone 2609 moves inward toward the stator 219.

[0128] FIG. 26C illustrates the actuatable tail cone 2609 in a fully extended state according to the second embodiment. In the fully extended state, the positions of the concentric rings 2607 are adjusted to provide a minimum amount of overlap between the concentric rings 2607. In the fully extended state, the exhaust control system 2601 reduces the outlet area of ​​the propulsor fan system 2600 to an area corresponding to a minimum thrust of the propulsor fan system 2600. For example, thrust is reduced at a constrained design speed. The outlet area is reduced as the middle portion 2705 of the actuatable tail cone 2609 moves outward away from the stator 219, thereby reducing the outlet area.

[0129] 26B shows the actuatable tail cone 2609 in an intermediate state between fully extended and fully retracted states according to a second embodiment. In the intermediate state, the positions of the concentric rings 2607 are adjusted to create an intermediate amount of overlap between the concentric rings 2607. The intermediate amount of overlap is greater than the minimum amount of overlap in the fully extended state, but less than the maximum amount of overlap in the fully retracted state. Although only one intermediate state is shown, the actuatable tail cone 2609 can be positioned in a number of different intermediate states between the fully extended and fully retracted states.

[0130] In one embodiment, the minimum and maximum lengths of the actuable tail cone 2609 vary depending on the application it is used in. For example, if the propulsion fan system 2600 is used in a small drone, the actuable tail cone 2609 may have a shorter length range than the length range of the actuable tail cone 2609 used in an aircraft configured to transport people.

[0131] In the second embodiment of the propulsion fan system 2600, the end of the duct 2603 in the embodiment shown in FIG. 26 is shaped differently from the duct 2501 of the propulsion fan system 2200 shown in FIG. 25. The outlet area of ​​the duct 2603 in the second embodiment of the propulsion fan system 2600 may have a similar or the same shape as the outlet of the propulsion fan 100. Thus, the outlet area of ​​the propulsion fan system 2600 may be circular, but the outlet area of ​​the propulsion fan system 2600 may be rectangular, for example. In one embodiment, the inner surface of the duct 2603 is shaped (e.g., contoured) based on the shape of the outer surface of the middle portion 2705 of the actuable tail cone 2609 (e.g., so that the inner surface of the duct 2603 is concave when the tail cone 2609 is convex).

[0132] As discussed above, the second embodiment exhaust control system 2601 includes a control mechanism for actuating the actuatable tail cone 2609. The control mechanism may include, for example, a motor 2605 and a rod 2611. The control mechanism may include other components in other embodiments.

[0133] The motor 2605 can be, for example, a servo motor or a torque motor. A first end of a rod 2611 is connected to the motor and a second end of the rod 2611 is connected to the tip of an actuatable tail cone 2609. The rod 2611 can be, for example, a screw. The motor 2605 moves the rod 2611 such that the rod pushes or pulls the second end of the tail cone 2609, causing the collars 2607 to slide relative to one another to change the length of the tail cone 2609. Although only one motor 2605 is shown, in other embodiments there are multiple motors 2605 actuating one tail cone 2609 to reduce loss of control in the event of a motor failure.

[0134] 28 shows a cross-sectional view of a propulsor fan system 2800 according to a third embodiment. The third embodiment of the propulsor fan system 2800 includes multiple exhaust control systems. For example, the third embodiment of the propulsor fan system 2800 includes both an exhaust control system 2201 having a flaperon 2205 as shown in FIGS. 22-25 and an exhaust control system 2601 having an actuable tail cone 2609 as shown in FIGS. 26-27.

[0135] The exhaust control system 2201 and the exhaust control system 2601 may be individually controlled to vary the area of ​​the exhaust of the propulsion fan system 2800 in the third embodiment. For example, FIG. 28 shows that the flaperon 2205 included in the exhaust control system 2201 and the actuatable tail cone 2609 included in the exhaust control system 2601 are individually actuatable. Both or either one may be altered to vary the thrust as described above with respect to the first and second embodiments of the exhaust control systems 2201, 2601. In some use cases, the flaperon 2205 may be used to vary the lift while the tail cone 2609 may be used to vary the thrust. In other cases, both the tail cone 2609 and the flaperon 2205 may be actuated to increase the exhaust area as much as possible, for example, during takeoff when a large thrust is required.

[0136] Conclusion References herein to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic is included in at least one embodiment of the present disclosure. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment.

[0137] While the present disclosure has been particularly shown and described with reference to one and several alternative embodiments, it will be understood by those skilled in the relevant art that various changes in form and details can be made therein without departing from the spirit and scope of the invention.

Claims

1. A tail cone configured for direct connection to a stator of a propulsion fan, a first end of the tail cone having a plurality of concentric annular portions including a first annular portion and a second annular portion, the first annular portion including a first end configured to connect to the stator of the propulsion fan and a second end of the first annular portion opposite the first end, the second annular portion including a first end that overlaps the second end of the first annular portion such that the second end of the first annular portion is inserted into the first end of the second annular portion and a second end of the second annular portion; a second end of the tail cone opposite the first end; and an intermediate section having an end, the second end of the second annular section being inserted into the end of the intermediate section, the intermediate section being disposed between the second end of the second annular section and the second end of the tail cone, the intermediate section having a diameter greater than a diameter of the first end of the tail cone and a diameter of the second annular section of the tail cone; a tail cone including an exhaust outlet area control mechanism configured to adjust an amount of overlap between the second end of the first annular portion and the first end of the second annular portion of the tail cone, and to adjust an amount of overlap between the second end of the second annular portion and the intermediate portion of the tail cone to adjust a length of the tail cone and vary a position of the intermediate portion within an outlet of the propulsion fan, thereby varying an area of ​​the outlet of the propulsion fan; An exhaust control system comprising:

2. The exhaust control system of claim 1 , wherein the exhaust outlet area control mechanism is connected to the second end of the tail cone.

3. 3. The exhaust control system of claim 2, wherein the exhaust outlet area control mechanism is configured to increase an amount of overlap between the plurality of concentric annular portions to shorten a length of the tail cone and bring the intermediate portion closer to the first end, thereby increasing an area of ​​an exit of the propulsion fan to increase thrust.

4. 4. The exhaust control system of claim 3, wherein the exhaust outlet area control mechanism is configured to reduce an amount of overlap between the plurality of concentric annular portions to increase a length of the tail cone and move the intermediate portion further from the first end, thereby reducing an area of ​​an exit of the propulsion fan and reducing thrust.

5. 1. A propulsion fan configured to generate thrust, comprising: A stator; a tail cone configured to connect to the stator, a first end of the tail cone having a plurality of concentric annular portions including a first annular portion and a second annular portion, the first annular portion including a first end configured to connect to the stator of the propulsion fan and a second end of the first annular portion opposite the first end, the second annular portion including a first end that overlaps the second end of the first annular portion such that the second end of the first annular portion is inserted into the first end of the second annular portion and a second end of the second annular portion; a second end of the tail cone opposite the first end; and an intermediate section having an end, the second end of the second annular section being inserted into the end of the intermediate section, the intermediate section being disposed between the second end of the second annular section and the second end of the tail cone, the intermediate section having a diameter greater than a diameter of the first end of the tail cone and a diameter of the second annular section of the tail cone; a tail cone including A propulsion fan including: an exhaust outlet area control mechanism configured to adjust an amount of overlap between the second end of the first annular portion and the first end of the second annular portion of the tail cone, and to adjust an amount of overlap between the second end of the second annular portion and the intermediate portion of the tail cone to adjust a length of the tail cone and vary a position of the intermediate portion within an outlet of the propulsion fan, thereby varying an area of ​​the outlet of the propulsion fan; A propulsion system comprising:

6. 5. The exhaust control system of claim 4, wherein a minimum area of ​​the propulsion fan outlet corresponds to a first position of a portion of the intermediate section having a maximum diameter that is aligned with a trailing edge of the propulsion fan outlet, and a maximum area of ​​the propulsion fan outlet corresponds to a second position of the portion of the intermediate section that is inserted from a trailing edge of the propulsion fan outlet when an amount of overlap between the plurality of concentric annular portions is maximum.

7. The propulsion system of claim 5 , wherein the exhaust outlet area control mechanism is connected to the second end of the tail cone.

8. 8. The propulsion system of claim 7, wherein the exhaust outlet area control mechanism is configured to increase an amount of overlap between the plurality of concentric annular portions to shorten a length of the tail cone and bring the intermediate portion closer to the first end, thereby increasing an area of ​​an exit of the propulsion fan to increase thrust.

9. 9. The propulsion system of claim 8, wherein the exhaust outlet area control mechanism is configured to reduce an amount of overlap between the plurality of concentric annular portions to increase a length of the tail cone and move the intermediate portion further from the first end, thereby reducing an area of ​​the propulsion fan exit and reducing thrust.

10. 10. The propulsion system of claim 9, wherein a minimum area of ​​the propulsion fan outlet corresponds to a first position of a portion of the intermediate section having a maximum diameter that is aligned with a trailing edge of the propulsion fan outlet, and a maximum area of ​​the propulsion fan outlet corresponds to a second position of the portion of the intermediate section that is inserted from a trailing edge of the propulsion fan outlet when an amount of overlap between the multiple concentric annular portions is maximum.

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