Pneumatic foldable ejector supply system for aircraft propulsion

Abstract

The propulsion system includes at least one duct, where the duct is configured to carry and distribute motive fluid, and the duct is further configured to be folded when motive fluid is not supplied from the compressor and to expand when motive fluid is supplied from the compressor, at least one ejector in fluid communication with the at least one duct, where the compressor supplies compressed air to the at least one ejector to generate thrust, and the at least one ejector can be stored in a volume of the airfoil that streamlines the outside of the airfoil when not in use.

Description

Copyright Notice

[0001]

[0001] This disclosure is protected under U.S. and / or international copyright laws. (C)2023 JETOPTERA, INC., All Rights Reserved. Part of the disclosure of this patent document contains material subject to copyright protection. The copyright owner does not object to the reproduction of the patent document or patent disclosure by anyone in connection with the filing of the patent file or record in the Patent and / or Trademark Office, but reserves all copyrights in all other cases. Priority Claim

[0002]

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 355,043, filed on June 23, 2022, the content of which is incorporated herein by reference as if fully set forth herein.

Background Art

[0003]

[0003] One of the greatest limitations in vertical takeoff and landing (VTOL) aircraft is the forward speed these aircraft are capable of. Rotary-wing aircraft are particularly efficient when using propellers and rotors to generate a very high hovering efficiency defined as the amount of vertical force (pounds of weight or newtons) generated per unit of power used (horsepower or watts).

[0004]

[0004] Helicopters function well in this category and are capable of hovering and taking off vertically very efficiently with a hovering efficiency in the range of 5 - 12 lbf / hp (or 3 - 7.5 kg / kW). However, their forward speed is extremely limited compared to other aircraft due to limitations of the rotors at forward speed, resulting in losses due to the retreating blade falling well below the supersonic local speed while the forward blade tip may transition to supersonic flow.

[0005]

[0005] To increase the forward speed limit, some manufacturers have introduced compound helicopters that use a dedicated fan or rotor to push the helicopter forward, but the rotor can only be used for vertical lift. However, even this method has severe limitations, and the fastest compound helicopters cannot achieve a forward speed exceeding 250 knots and are only possible at high altitudes.

[0006]

[0006] To overcome this, rotorcraft manufacturers have introduced tiltrotors. Tiltrotors have the advantage of minimizing the weight of the powerplant required to push the aircraft forward at high speeds while also performing the vertical flight propulsion function. However, it is complex and has weaknesses in rotor control and synchronization. The maximum forward speed that a tiltrotor can achieve is 320 knots at very high altitudes and is not faster than 250 knots at sea level.

[0007]

[0007] It is desirable to have a vertical takeoff and landing aircraft that can increase the forward speed limit.

Brief Description of the Drawings

[0008]

Figure 1

[0008] An ejector in the deployed position and an inflated conduit according to an embodiment are illustrated.

Figure 2

[0009] An ejector in the stowed position and a contracted conduit according to an embodiment are illustrated.

Best Mode for Carrying Out the Invention

[0009]

[0010] Embodiments of the present invention are applicable to both vertical takeoff and landing aircraft and short conventional takeoff and landing aircraft.

[0010]

[0011] A Fluid Propulsion System (FPS) is a propulsion system that can be integrated into an aircraft wing and can become integral with the wing. Using these FPS ejectors as a Boundary Layer Control (BLC) system, in addition to the ability to increase lift, this approach also enables wings that support these thrusters, which can have a non-circular shape, to have a triple stall margin (i.e., be able to operate at higher angles of attack), whereas otherwise, a clean wing would stall via separation of the boundary layer on the suction side.

[0011]

[0012] Accelerating faster in level flight remained a challenge because the ejectors are no longer highly efficient at higher speeds, and the protrusions formed by the ejectors placed on the wing induce high drag, preventing the aircraft from exceeding a speed of 200 knots.

[0012]

[0013] Therefore, it is advantageous to implement a method of housing these ejectors within the wing to enable smoother acceleration at higher speeds with a lower drag coefficient. In addition, housing the ejectors may actually require a wing profile of a large thickness that can accommodate these ejectors. The ejectors are also supplied, for example, via a pneumatic network of pipes and ducts that connect a turbo compressor, used to compress air, to the thruster-ejector. The network is pressurized with motive air supplied to the thruster during use and is not pressurized when not in use. The volume thus created by the pipes or ducts, which needs to be large enough to minimize losses, occupies a large space within the wing. To enable the use of a thinner wing profile by the wing, it is desirable to minimize this space, which, conversely, enables much higher speeds during forward flight.

[0013]

[0014] Embodiments of the present invention combine a flexible material for use in such conduits 102, which can be made of a material such as silicone that is soft but highly reliable and elastic and capable of multiple compression and extension cycles, with the geometry of the airfoil 110 and the architecture of the fluid propulsion system used on the airfoil. That is, the airfoil includes a series of compartments 100 along its wingspan that house such expandable material connected to the thruster 101, has openings on the negative pressure side of the airfoil, and the compartments are capable of compressing an unpressurized conduit when the thruster is extended and stored within the airfoil until the entire body of the thruster is fully housed inside the airfoil.

[0014]

[0015] In the scenario in which the thruster is to be used, the mechanism 104 extends the thruster out of the airfoil while the conduit 102 receives compressed motive air 111 from a compressor. The motive air 111 rapidly expands the conduit 102 and allows the thruster 101 to freely flow the motive air through a primary nozzle, thereby minimizing the risk of blockage. Since compressed air serves this process, the mechanism for extending the thruster 101 can also be minimized. The thruster 101 is connected to an expandable conduit 102 in a known manner of attaching a valve 103, similar to, for example, a tire from the automotive or truck industry. When fully inflated, the conduit 102 also has design features that allow it to fill non-circular, for example, compartments shaped to the rectangle of the airfoil while allowing for minimal friction of flow (and thus minimal pressure loss), so that the thickness of the airfoil can be minimized by avoiding the circular shape of the pipe.

[0015]

[0016] The top 105 of the thruster 101 can have panels that can completely seal the negative pressure side of the airfoil when the thruster is stored. When extended, they can be shaped so that minimal drag results from their configuration.

[0016]

[0017] While stored, for example, at 150 knots, the valve system can be used to directly send compressed air acting as motive fluid as a convergent or convergent-divergent jet that pushes the aircraft forward. When the thruster is stored, the lift-to-drag ratio of the aircraft significantly increases, thus minimizing the need for higher horizontal thrust.

[0017]

[0018] In one embodiment, the lift-to-drag ratio (L / D) of the aircraft 120 increases from 10 to 15 by housing the thruster within the wing, so that the aircraft requires 1.5 times less thrust to maintain its current speed. However, by keeping the level of work rate (i.e., the flow of motive air expanding as a jet) constant, the airplane significantly accelerates beyond 150 knots to 300 - 400 knots depending on the airfoil thickness and wing size. With this approach, a tiltrotor or any rotary-wing aircraft can achieve a forward speed significantly exceeding 100 knots. When the thruster is out, the valve pushes all the air to fill the network of conduits supplying the thruster, and the high-speed nozzles no longer operate (e.g., for speeds less than 150 knots), and the aircraft decelerates while sending compressed air from the high-speed nozzles to the thruster at an increasingly higher rate, and eventually the aircraft can operate solely with the thruster and decelerate to make a fully vertical landing in FPS.

[0018]

[0019] This application is intended to describe one or more embodiments of the invention. It should be understood that absolute terms such as "must", "will", and the like, as well as the use of specific quantities, are to be construed as applicable to one or more of such embodiments, but not necessarily to all such embodiments. Thus, embodiments of the invention may omit one or more features or functions described in the context of such absolute terms or may include modifications thereof. Additionally, the headings in this application are for reference purposes only and in no way affect the meaning or interpretation of the invention.

[0019]

[0020] Although the foregoing text describes detailed explanations of numerous different embodiments, it should be understood that the scope of protection is defined by the language of the following claims. The detailed description should be construed only as illustrative and is not intended to describe all possible embodiments, as it is unrealistic, if not impossible, to describe all possible embodiments. Using either current technology or technology developed after the filing date of this patent, numerous alternative embodiments can be implemented, and they will still be encompassed within the scope of the claims.

[0020]

[0021] Accordingly, many modifications and variations can be made to the techniques and structures described and illustrated herein without departing from the spirit and scope of the claims. Therefore, it should be understood that the methods and apparatuses described herein are merely illustrative and do not limit the scope of the claims.

Claims

**Claim 1** A propulsion system comprising: At least one duct configured to carry and distribute motive fluid, the duct being further configured to be collapsible when motive fluid is not supplied from a compressor and to expand when motive fluid is supplied from the compressor; At least one ejector in fluid communication with at least one of the ducts, wherein the compressor supplies compressed air to at least one of the ejectors to generate thrust, and at least one of the ejectors is stowable within a volume of the airfoil that streamlines an outer side of the airfoil when not in use; A system comprising the above. **Claim 2** The system of claim 1, wherein the airfoil is a component of at least one of a VTOL, STOL, or CTOL aircraft.

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