Propulsor wing trailing edge exhaust area control

Abstract

To provide a propulsor fan system configured to vary the area of the exhaust to adjust a magnitude of thrust and / or a thrust direction.SOLUTION: A propulsor fan system includes an exhaust control system and a propulsor fan. The exhaust control system is connected to the propulsor fan and is configured to vary an area of the exhaust of the propulsor fan system.SELECTED DRAWING: Figure 22

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.

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

[0003] Conventional thrusters have circular or other circular cross sections at both the inlet and outlet ends. While continuity of the circular shape throughout can allow for smooth airflow through the thruster, having a circular cross section outlet limits how the outlet area can be addressed. Some conventional examples with circular outlet cross sections use slide plates to control the outlet area of ​​the thruster. However, the circular cross section of the outlet complicates placement of the slide plate along the circular outlet and control of the slide 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. Varying the exhaust area can adjust thrust magnitude and / or thrust direction.

[0005] In one embodiment, an 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 propulsion fan configured to generate thrust. The first end has a first cross-sectional shape that substantially matches the cross-sectional shape of the propulsion fan outlet. 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 the exhaust area control mechanism configured to vary the 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 located at the 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 varies, the exhaust area of ​​the propulsion fan varies. [Brief explanation 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 duct lip of a propulsion fan according to one embodiment. [Figure 3C] FIG. 3C illustrates a side view of a duct lip of a propulsion fan according to one embodiment. [Figure 3D] FIG. 3D illustrates a cross-sectional view of a propulsion fan duct lip according to one embodiment. [Figure 4A] FIG. 4A illustrates a perspective view of a cross section of a propulsion fan nosecone, according to one embodiment. [Figure 4B]FIG. 4B illustrates a front view of a propulsion fan nosecone cross section, 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 cross section of a propulsion fan nosecone, according to one embodiment. [Figure 5A] FIG. 5A illustrates a front view of a propulsion fan hub according to one embodiment. [Figure 5B] FIG. 5B illustrates a side view of a propulsion fan hub according to 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 shows 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 shows 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 shows 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 according to one embodiment. [Figure 8C] FIG. 8C illustrates a side view of a propulsion fan retaining ring according to one embodiment. [Figure 9A] FIG. 9A illustrates a perspective view of a tension ring of a propulsion fan according to one embodiment. [Figure 9B] FIG. 9B illustrates a side view of a tension ring of a propulsion fan according to one embodiment. [Figure 10A] FIG. 10A illustrates a perspective view of a housing of an inner duct body of a propulsion fan according to one embodiment. [Figure 10B] FIG. 10B illustrates a front view of the propulsion fan inner duct body housing according to one embodiment. [Figure 10C] FIG. 10C illustrates a side view of the propulsion fan inner duct body housing according to 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 propulsion fan stator according to one embodiment. [Figure 11C] FIG. 11C illustrates a side view of a propulsion fan stator 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 according to one embodiment. [Figure 12C] FIG. 12C illustrates a side view of a tail cone of a propulsion fan according to one embodiment. [Figure 12D] FIG. 12D illustrates a cross-sectional view of a tail cone of a propulsion fan according to 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 according to 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 shows 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 propulsion fan array, according to one embodiment. [Figure 18C] FIG. 18C shows a top view of a cine drone including a propulsion fan array, according to one embodiment. [Figure 19A] FIG. 19A illustrates a front view of a transport including a propulsion fan array, according to one embodiment. [Figure 19B] FIG. 19B illustrates a side view of a transport 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 according to one embodiment. [Figure 20C] FIG. 20C illustrates a top view of a vertical take-off and landing (VTOL) aircraft including a propulsion fan array according to one embodiment. [Figure 21A] FIG. 21A shows 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 shows a first perspective view of a propulsion fan system having an exhaust control system according to a first embodiment. [Figure 23] FIG. 23 shows a second perspective view of the propulsion fan system with the exhaust control system according to the first embodiment. [Figure 24] FIG. 24 shows 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 emission control system according to the first embodiment. [Figure 25B] FIG. 25B shows different states of the emission control system according to the first embodiment. [Figure 25C] FIG. 25C shows different states of the emission 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 shows a cross-sectional view of a propulsion fan system having an exhaust control system according to a second embodiment. [Figure 26C] FIG. 26C shows 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 shows a cross-sectional view of a propulsion fan system having an exhaust control system according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] The drawings and the following description describe specific embodiments for purposes of example 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 practical, 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. Generally, 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, 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 one embodiment. Generally, the propulsion fan 100 includes multiple components that collectively reduce the noise emitted by the propulsion fan 100 during thrust generation. Therefore, the propulsion fan 100 reduces noise pollution. For example, the propulsion fan 100 includes tensioned fan blades, each of which includes a plurality 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 the fan blade angle is maintained within a predetermined tolerance. For example, the propulsion fan 100 emits less than 65 dBA at 300 feet of sideline / 5,000 lbf.

[0011] FIG. 2A illustrates a first exploded view of a propulsion fan 100 according to one embodiment, and FIG. 2B illustrates a second exploded view of the propulsion fan 100 according to one embodiment. The propulsion fan 100 includes several different components as shown in FIGS. 2A and 2B. In one embodiment, the propulsion fan 100 includes a duct lip 201, a nose cone 203, a hub 205, fan blades 209, a retaining ring 210 (shown in FIGS. 8A-8C), a tension ring 211, a motor 215, a body housing 217, a plurality 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 FIGS. 2A and 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 a perspective view, a front view, a side view, and a cross-sectional view, 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 unturbulent inflow of air to the propulsion fan 100. In one embodiment, the duct lip 201 is configured to connect to the main body housing 217. The duct lip 201 may include a plurality 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 in the mounting holes 223 to connect the duct lip 201 to the first end 1001 of the main body housing 217, as described further below.

[0013] The duct lip 201 may include multiple 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 each other 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 a metal, such as aluminum or titanium, or a composite material, such as carbon fiber. Alternatively, the duct lip 201 may be made from a single material, for example, by 3D printing.

[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 in other embodiments, the diameters may be the same. 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 may be larger for aircraft applications compared to leaf blower applications.

[0015] FIG. 3D is a cross-sectional view of duct lip 201 along plane A-A' shown in FIG. 3B, according to one embodiment. As described above, duct lip 201 includes outer surface 307 and inner surface 309. Both outer surface 307 and inner surface 309 extend from first end 303 of duct lip 201 toward second end 305 of duct lip 201. Air flows through inner surface 309 of duct lip 201. Curvature 311A ​​of inner surface 309 of duct lip 201 and curvature 311B of outer surface 307 of 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 number. One skilled in the art can tailor the duct lip radius for desired pressure gradients 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 nosecone 203 of a propulsion fan 100, according to one embodiment. The nosecone 203 is configured to match the behavior of oncoming airflow and reduce aerodynamic drag. The nosecone 203 can also be configured with an impeller that channels air at a cooling airflow 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 plurality of mounting holes on a back 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. As described further below, the fasteners 207 extend through the hub 205 and connect to a first end of the motor 215.

[0018] In one embodiment, the nosecone 203 is conical. However, in other embodiments, the nosecone 203 can have a different shape. As shown in FIGS. 4A through 4D , the nosecone 203 includes an opening 403 (e.g., a hole) at a first end of the nosecone 203. As the fan blades 209 rotate, air is drawn through the opening 403 in the nosecone 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 nosecone 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 nose cone 203 taken along plane B-B' shown in FIG. 4B, according to one embodiment. In one embodiment, nose cone 203 is not solid but includes a cavity. For example, in one embodiment, nose cone 203 includes air passage 405. Air passage 405 extends from an opening 403 in nose cone 203 to a plurality of openings 407 disposed around the circumference of a second end (e.g., rear) of nose cone 203. Air flows from opening 403 through air passage 405 and exits through the plurality of openings 407 to cool motor 215. In one embodiment, air passage 405 is formed between an outer surface 409 of nose cone 203 and a protrusion 411 formed in nose cone 203, as shown in FIGS. 4C and 4D.

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

[0021] Generally, protrusion 411 has a size and shape tailored to accommodate a rate of airflow for cooling motor 215. In one embodiment, protrusion 411 includes an air passage 413 formed therethrough through which air flows from an opening 415 in air passage 413 to an opening 417 in the second end of nosecone 203. In one embodiment, the center of air passage 413 is aligned with the center of opening 403 in nosecone 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. In one embodiment, the hub 205 is configured to connect to the nosecone 203, the retaining ring 210, and the motor 215.

[0023] As shown in FIGS. 5A and 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 nosecone 203. The first end 507 (e.g., the front) of the hub 205 includes a plurality 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 nosecone 203 connects to the first end 507 of the hub 205, the mounting holes 501 align with the mounting holes of the nosecone 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 in the first end of the motor 215.

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

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

[0026] In one embodiment, a second end 511 of the hub 205, opposite the first end 507, includes a connection mechanism 509 around the 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 threaded onto 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 the outer surface of the second end 511 of the hub 205.

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

[0028] 6A and 6B illustrate perspective and front views, respectively, of a fan blade 209 of a propulsion fan 100 according to one 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 greater than the number of vanes in a conventional propulsion fan, which may have between two and five vanes. In one embodiment, the fan blade 209 may include between 20 and 840 vanes 601. However, any number of vanes greater than five may be used. In general, the total number of vanes 601 included in the fan blade 209 will depend on the application. In one embodiment, the material for the vanes of a multi-blade fan will depend on the type of application for the multi-blade fan. The vanes may be made of a metal, such as aluminum or titanium, or a composite material, 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 / s). As described herein, tensioned fan blades 209 allow for more vanes to achieve ultrasonic signatures and low subsonic tip speeds while remaining within mechanical material limits. Furthermore, a high number of vanes 601 raises the acoustic noise into ultrasonic frequencies above the upper limit of human audibility (above 16,000 Hz for a typical adult). Furthermore, the lower vane loading resulting from 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 annulus with a hollow center in which the hub 205 is located. Each vane 601 is arranged so that at least a portion of the leading and trailing edges of the vane 601 overlap 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 increased stiffness for operation against the incoming airflow. This stiffness can be adjusted to account for local aerodynamic effects and Reynolds number effects, which can affect laminar flow attachment within and between the vanes.

[0031] 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 includes 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 in addition to 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] 7A-7D, first fixed end 605 is rectangular in shape with chamfered edges, although other shapes can be used for first fixed end 605. In one embodiment, first fixed end 605 has a width and thickness that is greater than the width and thickness of the tips of wings 607. However, in other embodiments, first fixed end 605 can be the same width as or narrower than the tips of wings 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 tensioning the root of the vane 601, the pitch (e.g., angle) of the root of the vane 601 remains substantially the same during thrust generation or while the propulsion fan 100 is stopped, thereby reducing noise pollution. As shown in FIGS. 7A-7D , the second fixed end 603 has multiple different surfaces (e.g., straight surfaces and curved surfaces) to increase the contact area with the fixing ring 210 so as to reduce deflection of the vane. In one embodiment, the second fixed end 603 has a width that is 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 as 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 vane 601. That is, geometric twist 609 causes wing 607 to have multiple different angles of incidence along the length of wing 607. For example, wing 607 may 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 vane 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 by 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 wing portions 607 of each vane 601 overlap with other wing portions of adjacent vanes 601 due to the geometric twist 609 in the wing portions 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 exert 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 smaller diameter than the second end 803, thereby forming a conical shape. This shape adjustment is driven by the need for primary internal flow (i.e., not cooling flow) to the fan and may also account for any boundary layer pressure gradient 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 securing the fan blades 209 to the stationary ring 210. The first end 801 of the stationary ring 210 includes a plurality of stationary tines 805. In one embodiment, the stationary tines 805 are protrusions extending from the main 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, slot 807 is formed between a pair of stationary teeth including stationary tooth 805A and stationary tooth 805B. Slot 807 has a width and depth that matches the dimensions of second stationary end 603 of fan blade 209. Slot 807 extends partially through the thickness of stationary ring 210, for example, three-quarters of the thickness of 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 blades 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 surface of the second fixed end 603 and the retaining teeth 805 that form the slot. In one embodiment, a fastener, such as 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 remains substantially the same during thrust generation or deactivation, thereby reducing audible noise emitted from the propulsion fan 100 because changes in pitch are perceptible to the human ear.

[0042] In one embodiment, second end 803 of retaining ring 210 includes a connection mechanism 809 on an inner periphery of second end 803 of retaining ring 210. Connection mechanism 809 is configured to connect retaining ring 210 to connection mechanism 509 of hub 205, for example. In one embodiment, connection mechanism 809 is a thread that mates with the threads of connection mechanism 509 of hub 205, thereby allowing hub 205 to be threaded onto retaining ring 210. Because motor 215 is connected to hub 205, hub 205 rotates, thereby causing retaining ring 210 and 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 securing 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 because pitch changes are perceptible to the human ear. Therefore, pre-tensioning the vanes 601 with the tension ring 211 reduces inefficiencies due to tip clearance. 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 the 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 reference perpendicular 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 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 illustrate a perspective view, a front view, and a side view, 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) 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, in other embodiments, other materials may be used.

[0048] In one embodiment, the main body housing 217 is cylindrical and includes a first end 1001 (e.g., an inlet) and a second end 1003 (e.g., an outlet). The first end 1001, in one embodiment, has a diameter that is larger than the diameter of the second end 1003. The first end 1001 includes a plurality of mounting holes 1005 formed around the circumference of the first end 1001 of the main body housing 217. In one embodiment, the first end 1001 of the main 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 main body housing 217. As described above, fasteners 207 can be used to secure the duct lip 201 to the first end 1001 of the duct main 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. While the second end 1003 of the body housing 217 is connected to the first end 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. Fasteners (e.g., nuts, bolts, rivets) can be used to secure the second end 1003 of the body housing 217 to the first end of the stator 219.

[0050] In one embodiment, the main body housing 217 includes multiple intermediate sections 1009, each configured to accommodate a different component of the propulsion fan. The multiple intermediate sections 1009 include a first intermediate section 1009A extending from the first end 1001 and a second intermediate section 1009B extending from the second end 1003. The intermediate sections 1009 of the main body housing 217 are located between the first end 1001 and the second end 1003 of the main body housing 217.

[0051] 10C, the first intermediate portion 1009A has a diameter different from the diameter of 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, first intermediate portion 1009A is configured to house hub 205, fan blades 209, retaining ring 210, and tension ring 211. Because tension ring 211 has the largest diameter of the components housed in first intermediate portion 1009A, the diameter of first intermediate portion 1009A is based on the diameter of tension ring 211. In one embodiment, the diameter of first intermediate portion 1009A is substantially the same as the diameter of tension ring 211, thereby allowing tension ring 211 to be securely secured within first intermediate portion 1000A, for example, by a press fit.

[0053] In one embodiment, the second intermediate section 1009B is configured to accommodate the motor 215 and a portion of the stator 219. The length of the second intermediate section 1009B is based on the length of the motor 215 and the length of the portion of the stator 219 accommodated in the intermediate section. The second intermediate section 1000B has a length at least as long as the motor 215 and the portion of the stator 219 so that the second intermediate section 1009B contains the motor 215 and the portion of the stator 219. In one embodiment, the diameter of the second intermediate section 1009B is based on the air flow rate entering and exiting 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 section 1009B can also be adjusted to reduce noise.

[0054] 11A, 11B, 11C, and 11D show a perspective view, a front view, a side view, and a cross-sectional view, respectively, 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 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, but not 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 depend 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] 11B and 11D, the motor housing 219B includes a hole 1113 through the center of the motor housing 219B. 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 a motor housing 219B. That is, the root of each vane 219A is connected to the motor housing 219B, and the vanes of the stator vane 219 extend outward from the motor housing 219B. In one embodiment, each vane 219A extends away from the motor housing 219B at an angle measured relative to a reference line extending 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. Because the vanes 219A contact the motor housing 219B that houses the motor 215, air passing over the vanes 219A dissipates heat generated by the motor 215. In one embodiment, the arrangement of the vanes 219A also reduces noise generated by the fan blades 209 and controls the thrust generated by the propulsion fan 100. The number of vanes on the stator vanes 219A can be selected so that stator harmonics cancel out fan blade harmonics. In the case of an ultrasonic fan, due to locally low Reynolds numbers along the vanes, one skilled in the art will appreciate that the fan vanes 209 may have a greater number (e.g., total volume) of vanes 601 than the stator vanes 219A for preferred acoustics. This allows for a vane count anywhere between 50% and 200% for a particular design sound set.

[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 greater than the diameter of the second end 1109. As such, the stator housing 219C may have a conical shape. However, the stator housing 219C may 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] Tail cone 221 includes a first end 1201 (e.g., an inlet) and a second end 1203 (e.g., an outlet). In one embodiment, first end 1201 has a larger diameter than second end 1203. In one embodiment, the diameter of tail cone 221 varies along the length of tail cone 221. As shown in FIG. 12C, the diameter of tail cone 221 decreases from first end 1201 to second end 1203 until it reaches midpoint 1205. From midpoint 1205 to second end 1203, the diameter of 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. As such, 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 with (e.g., contacts) 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 tail cone 221 along plane D-D' shown in FIG. 12B. In one embodiment, tail cone 221 includes a cavity 1207 formed along the length of tail cone 221 starting from tail cone first end 1201 to tail cone second end 1203. The aft shape of tail cone 221 is adjusted by secondary flow exhausted from the interior of tail cone 221 relative to the expansion of the jet following the vane disk 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 In another 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 a perspective view, a front view, and a side view, 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 main 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. An auxiliary motor 1301 can replace or be used in conjunction with the motor 215 described above. Multi-motor redundancy allows for exceptional fault tolerance of the propulsion fan 100 system. For example, with four auxiliary motors 1301, the loss of one auxiliary motor has little to no significant impact on the normal operation of the propulsion machine. Even with the loss of another motor, the remaining auxiliary motors 1301 can increase their speed beyond their limit to generate sufficient thrust.

[0069] As shown in Figures 13A-13C, the auxiliary motors 1301A-1301D are radially spaced around the outer periphery 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 connects 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 toward the lower quadrant of the duct. Furthermore, rather than requiring a stator 219 to support the hub 205 that supports the centrally housed motor 215, the propulsion device can utilize the duct structure itself to accommodate the motor and its load. In addition to eliminating weight and drag, this also results in less broadband noise, typically caused by flow interaction at the stator. In one embodiment, the auxiliary motor 1301 can operate at a higher speed of 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. However, 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, a 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 FIGS. 15A and 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 one 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 stagger, sweep, taper, 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 aircraft conditions, such as, for example, the number of passengers aboard the aircraft, the speed and altitude conditions of the aircraft 1605, and the like.

[0072] Combining propulsion fans in an array opens up several control and thrust vectoring opportunities. Thrust can be simply 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 promote faster climbs and descents. This can be further enhanced by additional control surfaces on the trailing edge.

[0073] Spanwise combinations of ducts are 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 sweep, stagger, dihedral, and tapered configurations to suit the needs of the system. The choice of incorporating the propulsion fan array as a full biplane wing depends on the amount of thrust (negative drag) required and the relative size of the propulsion fans.

[0074] Propulsion fan applications 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 arrangement of propulsion fans, including a first propulsion fan 100A, a second propulsion fan 100B, and a third propulsion fan 100C. While the hovering drone 1700 includes only three propulsion fans, the hovering drone 1700 may include additional or fewer propulsion fans than those shown in FIGS. 17A-17C.

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

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

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

[0078] In one embodiment, the cinema drone 1800 is a biplane with a staggered, non-staggered configuration. 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 multiple propulsion fans. For example, the propulsion fan array included in wing 1801 includes propulsion fans 100A, 100B, 100C, and 100D, and the propulsion fan array included in wing 1803 includes propulsion fans 100E, 100F, 100G, and 100H. In this manner, 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 that points forward of the fuselage 1805. In the example shown in Figures 18-18C, the wings 1801 and 1803 may have a 20 degree anhedral wing and a 30 degree forward swept wing. 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 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 The wing area can be 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. The transport aircraft 1900 is an optionally manned VTOL aircraft. The transport aircraft 1900 may be hybrid or all-electric. The transport aircraft 1900 may fly, for example, at an operating altitude of 1,000 to 2,000 feet and a cruising speed of 130 to 250 knots over a range of 20 to 60 nautical miles.

[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 so 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 on a first side of the fuselage 1905 and is integrated into the wing 1901, and a second array of propulsion fans is on a second side of the fuselage 1905 and is integrated into the wing 1903. 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. In this manner, 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 FIGS. 19A-19C, the propulsion array includes eight propulsion fans, although any number of propulsion fans may be used.

[0084] In one embodiment, the transport aircraft 1900 has, by way of example, a maximum takeoff weight of 1,000 lbs and a target maximum payload weight of 220 lbs. 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 The wing area can be as large as 28.7 ft.

[0085] 20A, 20B, and 20C illustrate 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. VTOL aircraft 2000 is an optionally manned VTOL airplane. VTOL aircraft 2000 may be hybrid or all-electric. VTOL aircraft 2000 may fly a range of 20 to 400 nautical miles at a cruising speed of 130 to 250 knots at an operating altitude of 1,000 to 2,000 feet. In one embodiment, 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, the two wings 2001, 2003 form an angle that points forward 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 integrated into each wing 2001 and 2003. A first array of propulsion fans is on a first side of the fuselage 2005 and is integrated into wing 2001, and a second array of propulsion fans is on a second side of the fuselage 2005 and is integrated into wing 2003. For example, the propulsion fan array included in wing 2001 includes propulsion fans 100A, 100B, 100C, and 100D, while the propulsion fan array included in wing 2003 includes propulsion fans 100E, 100F, 100G, and 100H. In this manner, 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 FIGS. 20A-20C, the propulsion array includes eight propulsion fans, although any number of propulsion fans may be used.

[0088] The VTOL aircraft 2000 has, for example, a maximum takeoff weight of 5,000 pounds and a target maximum payload of 1,000 pounds (e.g., 3-4 passengers). Each propulsion fan 100 has a speed of, 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 length of 16.7 lb / ft 2 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 in excess of 20 minutes. The delivery drone 2100, in one embodiment, has a maximum cruising speed in excess of 50 mph.

[0090] Delivery drone 2100 is an example of an electric tailsitter VTOL drone configured to deliver cargo inside. In the example shown, delivery drone 2100 is a biplane with a consistent stagger. 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 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 on a first side of the fuselage 2105 and integrated into the wing 2101, and a second array of propulsion fans is on a second side of the fuselage 2105 and integrated into the wing 2103. 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. In this manner, 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 FIGS. 21A-21C, the propulsion array includes six propulsion fans, although any number of propulsion fans may be used.

[0092] In one example, the delivery drone 2100 has a maximum takeoff weight of 55 lbs and a target maximum payload weight of 5.5 lbs. Each propulsion fan 100 has a 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 wing loading of 21.9 ft 2 The wing area can be as large as 8.8 ft.

[0093] Free wing Because the propulsion fan 100 described herein has higher speed capabilities, exceeding 150 mph, it is desirable to provide increased propulsive efficiency through either variable blade angle or mass flow adjustment. As noted above, the propulsion fan 100 includes a significantly greater number of blades than conventional propulsors. Implementing a typical variable pitch propeller mechanism can be excessively cumbersome in terms of mechanical complexity.

[0094] In one embodiment, the propulsion fan array described above is incorporated into an aircraft using a free vane structure. The free vane structure may be implemented, for example, on 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 each vane's aerodynamic center. That is, the fan blades 209 are free to rotate about their radial axis due to mass balancing forward of each vane's aerodynamic center. The free vane combines airfoil design, blade mass balancing, and blade pivot axis to achieve free-pitch functionality by self-adjusting to zero pitching moment at a constant CL across all flight conditions.

[0095] The combination of the free vane structure and the propulsion fan 100 creates a passive system for varying the vane angle of attack (AoA) while maintaining constant vane loading. This can provide a unique synergy for the electric motor-driven propulsion fan 100, as 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 across 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 for achieving low noise as a way to avoid vane stall, which results in high noise under different flight conditions and turbulence levels.

[0096] The use of free vanes offers many advantages. For example, the free vanes are pitch-balanced by adding leading-edge vane mass to ensure that their AoA is always close to their L / DmaxCL (typically 0.5-1.0). This ensures that the vane AoA is always aligned with the inflow and that there is no separated flow. Furthermore, being peripherally driven allows for mass balancing in the propulsion fan 100 when the inner hub region is empty, providing volume forward of the vanes (and not exposed to the flow) for counterweights for the lightest mass balance. This allows the propulsion fan 100 to vary its RPM by on the order of approximately 50% during different flight segments, allowing the vanes to always be close to their optimal 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 RPM range for high efficiency. Thus, while turbines or IC engines must operate at a fixed RPM for a given power output, electric motors do not. This allows the thrusters to vary their RPM by on the order of about 50% during different segments of flight, ensuring the blades are always close to their optimum advance ratio. Finally, free blades 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 distributed electric 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 aircraft integration benefits at both the propulsor fan 100 and aircraft integration levels. Applying flow control to the duct lip 201 can, for example, increase static thrust by up to 40% for the same fan power.

[0098] In one embodiment, a high PR and intake velocity emergency power ram air turbine requires a high jet blowing velocity (i.e., a jet with near sonic noise) for flow control. A quieter, lower speed jet (~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 velocity. Flow control effectiveness is a function of Vjet / Vintake. Another interesting aspect of flow control duct lip blowing is the avoidance of separation at the 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 due to the fan blades being subjected to oscillating flow conditions that result in periodic blade loading.

[0100] By applying flow control blowing at the duct lip 201 at jet velocities of approximately 300 ft / s, the duct lip suction force can be increased to account for approximately 75% of the total static thrust. Blowing air at the duct lip 201 effectively deforms the duct lip's aerodynamic shape, drawing in additional ambient air. With the blowing on, the incoming air "sees" a much larger receptacle duct lip than is desired under static conditions. Using a true receptacle duct intake creates significant drag during cruise. The duct flow control blowing can be turned off during cruise flight, where the blowing is relatively ineffective. A compact, high-speed centrifugal blower operates at ultrasonic vane-pass frequencies, resulting in internal blowing. While flow control blowing is most effective at high nozzle jet velocities (optimally near the speed of sound), Applicant's nozzle jets are designed for low jet velocities to achieve low noise (jet noise scales as the tenth power of nozzle velocity). In this duct tip application, the goal is to maximize the inlet 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 mentioned, 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 farthest 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 and varies 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 thrust relative to the initial exhaust area thrust, while decreasing the exhaust area through which air exits the propulsion fan decreases thrust relative to the initial exhaust area thrust. Different configurations of exhaust control systems are further described below. While the following description relates to different embodiments of exhaust control systems coupled to individual propulsion fans 100, exhaust control systems may be added to arrays of the propulsion fans described above.

[0104] Figure 22 shows a first perspective view of a propulsion fan system 2200 having an exhaust control system 2201 according to the first embodiment, and Figure 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 port 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 1109 of the stator 219 to change the cross section of the exhaust port 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 port compared to changing the area of ​​the first shape. For example, the second shape is any shape with straight edges that form an enclosed area, such as a square, rectangle, parallelogram, or triangle. Due to the curved nature of a circle, controlling the area of ​​a circle is more complicated than controlling the area of ​​a rectangle.

[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 components other than those described herein. In one embodiment, transition portion 2202 is configured to transition the shape of the exhaust outlet from a first shape corresponding to the exhaust outlet of propulsion fan 100 to a second shape corresponding to the 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 port 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, ensuring that the airflow remains steady across the transition portion 2202. To ensure 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 may be, for example, a metal or composite material. Thus, the transition portion 2202 provides a smooth transition for changing the exhaust region 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 multiple 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, multiple flaperons 2205 are connected to second end 2204 of transition section 2202. In the example shown in FIG. 23, multiple flaperons 2205 include 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 of, for example, metal or composite material, although other cross-sectional shapes are possible. 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 orientation of the flaperon 2205 to change, thereby changing the exhaust area of ​​the propulsion fan system 2200. That is, the flaperons 2205 can be actuated as they move such that the flaperons 2205 can block a portion of the exhaust area, constricting the area, or move to a position that does not restrict the exhaust area.

[0112] Thus, in the first embodiment of the propulsion fan system 2200, air flows through the duct lip 201 into the propulsion fan 100, through the fan blades 209 (not shown), the tail cone 221, and the stator 219A, through the transition section 2202, and out an 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 as they move to vary the exhaust area of ​​the propulsion fan system 2200 to control the magnitude of thrust and / or thrust direction.

[0113] In some embodiments, the flaperons 2205 are individually controllable so 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, or 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 with 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 location (eg, the upper flaperon 2205A of each thruster in the array) may be operable together.

[0114] Figure 24 shows a cross-sectional view of the propulsion fan system 2200 along the plane A-A' shown in Figure 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 including a motor 2401 and a rod 2403. The motor 2401 is a torque or servo motor that either pushes the rod 2403, extending it and thereby moving the flaperon 2205 inward toward the tail cone 221, or pulls the rod 2403, retracting it and thereby moving the flaperon 2205 outward from the tail cone 221.

[0115] In the embodiment shown, when motor 2401 pushes rod 2403, flaperon 2205 rotates about hinge 2405, resulting in the flaperon tilting inward (e.g., toward tail cone 221). When motor 2401 pulls rod 2403 to retract it, the flaperon rotates about hinge 2405, angling outward (e.g., away from tail cone). Thus, as flaperon 2205 moves inward, the cross-sectional area of ​​the outlet region of propulsor fan system 2200 decreases, thereby decreasing thrust, assuming the fan blades 209 rotate at a constant RPM (rotational speed). Similarly, as flaperon 2205 moves outward, the cross-sectional area of ​​the outlet region of propulsor fan system 2200 increases, thereby increasing thrust, assuming the fan blades 209 rotate at a constant RPM. In this way, 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 remain controllable in the event of a motor or servo failure. In some embodiments, rod 2403 is a screw that, as motor 2401 rotates, translates forward or backward depending on the direction of rotation of 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, extension and contraction of the rod 2403 causes the flaperon 2205 to move in the opposite direction to that described above (e.g., extension results in an outward rotation and contraction results in an inward rotation).

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

[0119] Actuating the flaperon 2205 can change the size of the exhaust area to vary thrust, and can also actuate to change the direction of the airflow to vary lift. FIGS. 25A, 25B, and 25C show different positions of the flaperon 2205 according to one embodiment. For simplicity, the nose cone 203, motor housing 219B, and tail cone 221 are shown in FIGS. 25A-25C as a single central section 2503. In FIG. 25A, the upper flaperon 2205A is angled inward toward the central section 2503, and the lower flaperon 2205C is angled outward. In use cases where the propulsor is horizontal, such as vertical takeoff, the position of the flaperon 2205 in FIG. 25A directs air 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 that the aircraft drops and / or rotates. 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 flaperons 2205 rotate inward at approximately their maximum angle, providing the smallest possible outlet area for the propulsor fan system 2200 and therefore the lowest thrust as the air exits the propulsor fan system 2200. In one embodiment, the maximum inward angle of the flaperons is approximately 60 degrees, although other maximum inward angles are 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. By way of example, the initial position of the flaperon is shown in FIG. 24.

[0123] 26A, 26B, and 26C show cross-sectional views of a propulsion fan system 2600 according to a second embodiment. In one embodiment, the propulsion fan system 2600 includes a propulsion 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 according to 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 outlet area of ​​the propulsion 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, with the second end 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 of the concentric rings. The plurality of concentric rings 2607 may be considered an exhaust region 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 partially overlaps the 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 and changing the outlet 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 outlet area of ​​the stator 219, thereby reducing the outlet area and decreasing 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 create the maximum amount of overlap between the concentric rings 2607. In the fully retracted state, the exhaust control system 2601 increases the outlet area of ​​the propulsion fan system 2600 to an area corresponding to the maximum thrust of the propulsion fan system 2600. For example, thrust is increased at the most constrained design speed. The outlet area increases as the middle portion 2705 of the actuatable tail cone 2609 moves inward toward the stator 219.

[0128] 26C shows 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 create a minimal amount of overlap between the concentric rings 2607. In the fully extended state, the exhaust control system 2601 reduces the outlet area of ​​the propulsion fan system 2600 to an area corresponding to the minimum thrust of the propulsion fan system 2600. For example, thrust is reduced at a constrained design speed. The outlet area decreases 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 the 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 multiple different intermediate states between the fully extended and fully retracted states.

[0130] In one embodiment, the minimum and maximum lengths of the actuatable tail cone 2609 vary depending on the application in which it is used. For example, if the propulsion fan system 2600 is used in a small drone, the actuatable tail cone 2609 may have a shorter length range than the length range of an actuatable 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 than 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 identical shape to the outlet of the propulsion fan 100. Thus, while the outlet area of ​​the propulsion fan system 2600 may be circular, 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 actuatable 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 described 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. In other embodiments, the control mechanism may include other components.

[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, changing the length of the tail cone 2609. While only one motor 2605 is shown, in other embodiments there are multiple motors 2605 operating 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 propulsion fan system 2800 according to a third embodiment. The third embodiment of the propulsion fan system 2800 includes multiple exhaust control systems. For example, the third embodiment of the propulsion 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 actuatable tail cone 2609, as shown in FIGS. 26-27.

[0135] In the third embodiment, the exhaust control system 2201 and the exhaust control system 2601 may be independently controlled to vary the area of ​​the exhaust port of the propulsion fan system 2800. 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 independently actuatable. Either or both may be altered to vary 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 lift, while the tail cone 2609 may be used to vary thrust. In other cases, such as during takeoff when high thrust is required, both the tail cone 2609 and the flaperon 2205 may be actuated to maximize the exhaust port area.

[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 embodiment 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

[Claim 1] a first end configured to connect to an outlet of a propulsion fan configured to generate thrust, the first end having a first cross-sectional shape that substantially matches a cross-sectional shape of the propulsion fan outlet; a second end having a second cross-sectional shape different from the first cross-sectional shape, the second end configured to allow exhaust generated by the propulsion fan to exit the second end of an exhaust control system; an exhaust outlet area control mechanism configured to vary an area of ​​the second end of the exhaust control system from a first area to a second area smaller than the first area; An exhaust control system comprising:

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