FLIGHT VEHICLE WITH INTEGRAL GUIDANCE SENSOR WINDOW AND CAVITATOR FOR CONTROLLED UNDERWATER TRAJECTORY

Abstract

A flight vehicle configured for underwater trajectory includes a vehicle forebody attached to a fuselage. The flight vehicle forebody has a curved sensor window and an integral ring cavitator situated aft of the sensor window that triggers and manages cavitation underwater during the underwater trajectory. The placement of the integral ring cavitator aft of the curved sensor window provides the sensors with a forward field of view enabling guidance. The curved sensor window and the integral ring cavitator may be configured to transfer load at impact with water to the fuselage. The size and the shape of the of the integral ring cavitator, the location of the integral ring cavitator with respect to the forebody, and the shape of the curved sensor window are selected to generate a cavitation bubble and maintain a pitch angle when the flight vehicle is traveling underwater.

Claims

1. A flight vehicle configured for underwater trajectory, the flight vehicle comprising: a fuselage; and a flight vehicle forebody attached to the fuselage, the flight vehicle forebody comprising: a curved sensor window; and an integral ring cavitator situated aft of the sensor window, wherein the integral ring cavitator is configured to trigger and manage cavitation underwater during the underwater trajectory.

2. The flight vehicle of claim 1, wherein the curved sensor window and the integral ring cavitator are configured to transfer load at impact with water to the fuselage.

3. The flight vehicle of claim 2, wherein the integral ring cavitator comprises one or more full or partial rings.

4. The flight vehicle of claim 3, wherein each of the one or more full or partial rings comprises a substantially flat surface that is angled at 90 degrees or more with respect to a y-axis of the flight vehicle.

5. The flight vehicle of claim 4, wherein a size and a shape of the of the integral ring cavitator, a location of the integral ring cavitator with respect to the forebody, and a shape of the curved sensor window are selected to generate a cavitation bubble when the flight vehicle is traveling underwater.

6. The flight vehicle of claim 5, wherein the size and the shape of the of the integral ring cavitator, the location of the integral ring cavitator with respect to the forebody, and the shape of the curved sensor window are further selected to cause supercavitation when the flight vehicle is traveling underwater.

7. The flight vehicle of claim 5, further comprising gas injectors provided behind the integral ring cavitator to augment the cavitation bubble when the flight vehicle is traveling underwater.

8. The flight vehicle of claim 5, wherein the size and the shape of the of the integral ring cavitator, the location of the integral ring cavitator with respect to the forebody, and the shape of the curved sensor window are further selected to maintain a pitch angle of the underwater trajectory when the flight vehicle is traveling underwater within the cavitation bubble.

9. The flight vehicle of claim 5, wherein a shape of the forebody is configured to control the underwater trajectory

10. The flight vehicle of claim 5, wherein the integral ring cavitator comprises a single ring with a substantially flat surface that is angled up to degrees with respect to the y-axis of the flight vehicle, and wherein the integral ring cavitator has a height that extends no greater than a maximum diameter of the forebody at the fuselage.

11. The flight vehicle of claim 5, wherein the curved sensor window comprises an optically transparent material and is configured to house one or more optical sensors configured for optical guidance.

12. The flight vehicle of claim 11, wherein the curved sensor window comprises one of Sapphire, Aluminum oxynitride, Borosilicate glass, and a glass ceramic material.

13. The flight vehicle of claim 12, wherein the curved sensor window comprises a dome having a hemispherical surface.

14. The flight vehicle of claim 1, wherein the flight vehicle is an airflight diving vehicle having an initial portion of its trajectory in air and a subsequent portion of its trajectory underwater.

15. A flight vehicle forebody configured for attachment to a fuselage of a flight vehicle, the flight vehicle forebody comprising: a curved sensor window; and an integral ring cavitator situated aft of the sensor window, wherein the integral ring cavitator is configured to trigger and manage cavitation underwater during underwater trajectory of the flight vehicle.

16. The flight vehicle forebody of claim 15, wherein the integral ring cavitator comprises one or more full or partial rings, each of the one or more full or partial rings comprises a substantially flat surface that is angled at 90 degrees or more with respect to a y-axis of the flight vehicle.

17. The flight vehicle forebody of claim 16, wherein a size and a shape of the of the integral ring cavitator, a location of the integral ring cavitator with respect to the forebody, and a shape of the curved sensor window are selected to generate a cavitation bubble when the flight vehicle is traveling underwater.

18. A method for controlling underwater trajectory of a flight vehicle during underwater travel, the method comprising: triggering and managing cavitation underwater during underwater trajectory of the flight vehicle with an integral ring cavitator aft of a curved sensor window, the integral ring cavitator and the curved sensor window being an integral part of a flight vehicle forebody.

19. The method of claim 18, further comprising transferring load at impact with water to a fuselage with the curved sensor window and the integral ring cavitator, the fuselage being coupled to the forebody.

20. The method of claim 19, further comprising generating a cavitation bubble when the flight vehicle is traveling underwater, the cavitation bubble generated based on a size and a shape of the of the integral ring cavitator, a location of the integral ring cavitator with respect to the forebody, and a shape of the curved sensor window.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 illustrates a flight vehicle forebody with integral sensor window and ring cavitator, in accordance with some embodiments.

[0006] FIG. 2 illustrates a side view of flight vehicle with the flight vehicle forebody of FIG. 1, in accordance with some embodiments.

[0007] FIG. 3 illustrates generation of a cavitation bubble, in accordance with some embodiments.

[0008] FIG. 4 is a plot of underwater trajectory of a flight vehicle, in accordance with some embodiments.

DETAILED DESCRIPTION

[0009] The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in, or substituted for, those of other embodiments. Embodiments set forth in the claims encompass all available equivalents of those claims.

[0010] Embodiments disclosed herein are directed to a flight vehicle with an integral guidance sensor window and cavitator that provide a controlled and predictable underwater trajectory, while maintaining the necessary transparency for the guidance system. In some embodiments, the flight vehicle may be able to execute a controlled diving trajectory into water, while maintaining guided flight through optical means. In some embodiments, the flight vehicle is able to trigger and manage cavitation underwater during the underwater trajectory. In some embodiments, the flight vehicle is able to maintain a pitch angle of the underwater trajectory when the flight vehicle is traveling underwater within the cavitation bubble.

[0011] Some embodiments are directed to a flight vehicle configured for underwater trajectory. In these embodiments, the flight vehicle may comprise a fuselage and a flight vehicle forebody attached to the fuselage. The flight vehicle forebody may comprise a curved sensor window and an integral ring cavitator situated aft of the sensor window. The integral ring cavitator may be configured to trigger and manage cavitation underwater during the underwater trajectory. These embodiments, as well as others, are described in more detail below.

[0012] FIG. 1 illustrates a flight vehicle forebody with integral sensor window and ring cavitator, in accordance with some embodiments. The flight vehicle forebody 100 may be configured for attachment to a fuselage 202 (FIG. 2) of a flight vehicle. In these embodiments, the flight vehicle forebody may comprise a curved sensor window 104 and an integral ring cavitator 102 situated aft of the sensor window 104. In these embodiments, the integral ring cavitator may be configured to trigger and manage cavitation underwater during underwater trajectory of the flight vehicle.

[0013] FIG. 2 illustrates a side view of flight vehicle with the flight vehicle forebody of FIG. 1, in accordance with some embodiments. The flight vehicle 200 may be configured for underwater trajectory and may include a fuselage 202 and a flight vehicle forebody 100 attached to the fuselage. In these embodiments, the flight vehicle forebody may comprise a curved sensor window 104 and an integral ring cavitator 102 situated aft of the sensor window 104. In these embodiments, the integral ring cavitator may be configured to trigger and manage cavitation underwater during the underwater trajectory.

[0014] In these embodiments, the placement of the integral ring cavitator 102 aft of the curved sensor window 104 provides sensors with a forward field of view enabling the guidance field of view. In these embodiments, the integral ring cavitator 102 is unlike a conventional Kopfring which is intended to prevent skipping and reduce penetration in earth or water.

[0015] In some embodiments, the curved sensor window 104 and the integral ring cavitator 102 may be configured to transfer load at impact with water to the fuselage. In these embodiments, the use of integral ring cavitator 102 may reduce the load on the curved sensor window 104 allowing for use of a thinner and less costly materials.

[0016] In some embodiments, the size and the shape of the of the integral ring cavitator 102, the location of the integral ring cavitator 102 with respect to the forebody, and the shape of the curved sensor window 104 may be selected to generate a cavitation bubble 302 (FIG. 3) when the flight vehicle is traveling underwater (i.e., post impact). These embodiments allow cavitation behavior to be managed to control the underwater trajectory.

[0017] FIG. 3 illustrates generation of a cavitation bubble, in accordance with some embodiments. Cavitation occurs when a flight vehicle 200 enters the water, creating a cavity or cavitation bubble 302 around itself due to the rapid displacement of water and the reduction in pressure around the flight vehicle's surface. The initial phase of cavity formation is particularly problematic as it involves complex interactions between the flight vehicle's motion and the water's response. The flow separates from the flight vehicle nose with the generation of a cavity and that air rushes in from above the water to fill the cavity. This initial cavity formation is critical as it sets the conditions for the subsequent behavior of the flight vehicle underwater.

[0018] Controlling the cavity dynamics involves managing the cavity's growth and collapse as the flight vehicle penetrates deeper into the water. The cavity typically undergoes several phases, including expansion, surface closure, and eventual collapse. Each of these phases presents unique challenges. For example, during the 'open-cavity phase,' the cavity is susceptible to atmospheric conditions, and its interaction with the air can unpredictably alter its behavior.

[0019] The 'closed-cavity phase' is where the cavity closes above the water surface, enveloping the flight vehicle. This phase is crucial for maintaining flight vehicle stability, as any asymmetry in cavity closure can lead to trajectory deviations. The control over these phases is influenced by the flight vehicle's design, particularly the tail design and the distribution of mass along the flight vehicle, which affects its moment of inertia and stability during cavity-running phases.

[0020] Controlling the flight vehicle's trajectory underwater is complicated by the transient and dynamic nature of the cavity. As the flight vehicle moves forward, the cavity's shape and size continually change, influenced by factors such as flight vehicle speed, water density, and hydrodynamic forces. The motion of the flight vehicle within the cavity and the impacts of the flight vehicle with the cavity wall are critical factors that need to be managed to maintain a stable trajectory.

[0021] Moreover, the stability characteristics during the cavity-running phase are crucial for effective trajectory control. Instabilities can arise due to asymmetric cavity collapse or due to interactions between the flight vehicle's tail and the cavity wall, a phenomenon known as 'tail slap.' These interactions can lead to sudden changes in trajectory, making it difficult to predict and control the flight vehicle's path accurately.

[0022] There are many challenges associated with cavitation and cavity control for flight vehicles entering water. The dynamics of cavity formation and collapse, coupled with the need to maintain a stable and predictable trajectory underwater, present significant challenges that are influenced by the flight vehicle's design and entry conditions.

[0023] In some embodiments, the size and the shape of the of the integral ring cavitator 102, the location of the integral ring cavitator 102 with respect to the forebody, and the shape of the curved sensor window 104 may be further selected to cause supercavitation when the flight vehicle is traveling underwater. In these embodiments, during supercavitation, the entire flight vehicle may be within the cavitation bubble 302.

[0024] In some embodiments, the flight vehicle may also include one or more gas injectors provided behind (i.e., aft of) the integral ring cavitator 102 to augment the cavitation bubble 302 when the flight vehicle is traveling underwater, although the scope of the embodiments is not limited in this respect.

[0025] In some embodiments, the size and the shape of the of the integral ring cavitator 102, the location of the integral ring cavitator 102 with respect to the forebody, and the shape of the curved sensor window 104 may be further selected to maintain a pitch angle 402 (see FIG. 3 and FIG. 4) of the underwater trajectory when the flight vehicle is traveling underwater within the cavitation bubble. These embodiments provide a more predictable and more stable underwater trajectory.

[0026] FIG. 4 is a plot of underwater trajectory of a flight vehicle, in accordance with some embodiments. As shown in FIG. 4, a stable and constant pitch angle 402 may be maintained when the flight vehicle 200 is traveling underwater within the cavitation bubble.

[0027] In the example embodiments shown in FIG. 2, the integral ring cavitator 102 may comprise a single ring with a substantially flat surface that is angled back up to 100 degrees with respect to the y-axis 204 of the flight vehicle. In these embodiments, the integral ring cavitator 102 may have a height that extends no greater than a maximum diameter of the forebody at the fuselage 202 allowing the flight vehicle to fit within the launch tube, although the scope of the embodiments is not limited in this respect.

[0028] In some embodiments, the integral ring cavitator 102 comprises one or more full or partial rings. In some embodiments, the partial rings may be segmented rings or ring segments, although the scope of the embodiments is not limited in this respect. In some embodiments, each of the one or more full or partial rings comprises a substantially flat surface that is angled at 90 degrees or more with respect to a y-axis 204 (e.g., a longitudinal axis of the flight vehicle. In these embodiments, the surface of the integral ring cavitator 102 may be at 90 degrees with respect to the y-axis of the flight vehicle (i.e., orthogonal to the flow of water) or may be angled slightly backward as illustrated in FIG. 2. In some embodiments, the angle 206 may range from 90 degrees to up to 100 degrees or more, although the scope of the embodiments is not limited in this respect. In some embodiments, the angle 206 may be less than 90 degrees.

[0029] In some embodiments, the shape of the forebody may be configured to manage and control the underwater trajectory. In some embodiments, the diameter of the forebody 100 may expand aft of the integral ring cavitator 102, although this is not a requirement as the diameter of the forebody 100 may remain constant aft of the integral ring cavitator 102.

[0030] In some embodiments, the curved sensor window 104 comprises an optically transparent material and may be configured to house one or more optical sensors configured for precision optical guidance although the scope of the embodiments is not limited in this respect. These embodiments enable a clear field of view for the flight vehicles optical system. A forward field of view with variable vertical angle may also be provided. In other embodiments, the curved sensor window 104 comprises a material that is transmissive at wavelengths of interest (e.g., UV, IR, etc.).

[0031] In some embodiments, the curved sensor window 104 may be made from Sapphire, Aluminum oxynitride, Borosilicate glass, or a glass ceramic material, although the scope of the embodiments is not limited in this respect as the material for the curved sensor window 104 may be selected based on its transmissive properties at wavelengths of interest and structural properties. Aluminum oxynitride, for example, is an optically transparent ceramic material made of aluminum, oxygen, and nitrogen.

[0032] In some alternate embodiments, the curved sensor window 104 may be comprised of acoustically or electromagnetically transparent sensor window materials.

[0033] In some embodiments, the curved sensor window 104 may comprise a dome having a hemispherical surface, although the scope of the embodiments is not limited in this respect.

[0034] In some embodiments, the flight vehicle may be an airflight diving vehicle having a portion of its trajectory in air and a portion of its trajectory underwater. Embodiments disclosed herein are applicable to the control of water trajectories for guided and/or homing airflight vehicles at terminal or launch phases. In some embodiments, the flight vehicle may rise from the water into the air, although the scope of the embodiments is not limited in this respect.

[0035] Some embodiments are directed to a flight vehicle forebody 100 configured for attachment to a fuselage 202 of a flight vehicle. In these embodiments, the flight vehicle forebody may comprise a curved sensor window 104 and an integral ring cavitator 102 situated aft of the sensor window 104. In these embodiments, the integral ring cavitator 102 may be configured to trigger and manage cavitation underwater during underwater trajectory of the flight vehicle.

[0036] Some embodiments are directed to a method for controlling underwater trajectory of a flight vehicle during underwater travel. In these embodiments, the method may include triggering and managing cavitation underwater during underwater trajectory of the flight vehicle with an integral ring cavitator 102 aft of a curved sensor window 104. In these embodiments, the integral ring cavitator 102 and the curved sensor window 104 may be an integral part of a flight vehicle forebody 100.

[0037] In these embodiments, the method may also include transferring load at impact with water to a fuselage with the curved sensor window 104 and the integral ring cavitator 102, the fuselage being coupled to the forebody. In these embodiments, the method may also include generating a cavitation bubble 302 (FIG. 3) when the flight vehicle is traveling underwater. The cavitation bubble may be generated based on the size and the shape of the of the integral ring cavitator 102, the location of the integral ring cavitator 102 with respect to the forebody, and the shape of the curved sensor window 104.

[0038] Embodiments disclosed herein enable a flight vehicle to execute a controlled diving trajectory into water, or launch underwater emerging to flight in air, or maintaining waterborne trajectory, while maintaining guided flight through optical means. Some embodiments combine an optical window assembly with an integral ring cavitator. These embodiments maintain the forward field of view free for guidance and control, while enabling stable underwater diving motion. In addition, the ring cavitator is configured to minimize drag during airflight, compared to alternative diving-trajectory control alternatives. Some embodiments include spherical sensor windows with full circumferential rings, of various dimensions, and a means to optimize these dimensions for aerial and underwater performance criteria.

[0039] Conventional cavitator designs comprise disks or cones which interfere with optical guidance. Embodiments disclosed herein allow a clear field of view forward to be maintained, facilitating air flight performance and also enabling optional underwater guidance. The use of an integral ring cavitator situated aft of the sensor window yields provides cavitation control without optical interference. This combination functionally enables the use of optical guidance and controlled water-diving trajectories in a flight vehicle.

[0040] Embodiments disclosed herein are tolerant of the water trajectory of varying surface conditions (e.g., wavetops) and provide for a predictable and repeatable water trajectory. In accordance with these embodiments, the forebody allows for the packaging of sensor suite components, and a forward field of view with variable vertical angle for a camera/lens and rangefinder. In accordance with these embodiments, the forebody also is configured for generating a super-cavitation bubble without undue drag, as well as minimal structural loads at impact.

[0041] The Abstract is provided to comply with 37 C.F.R. Section 1.72(b) requiring an abstract that will allow the reader to ascertain the nature and gist of the technical disclosure. It is submitted with the understanding that it will not be used to limit or interpret the scope or meaning of the claims. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.