U.S. patent application number 12/399945 was filed with the patent office on 2012-04-12 for supercavitating projectile with reduced-drag control surfaces.
This patent application is currently assigned to Lockheed Martin Corporation. Invention is credited to Jyun-Horng Fu.
Application Number | 20120085257 12/399945 |
Document ID | / |
Family ID | 45921968 |
Filed Date | 2012-04-12 |
United States Patent
Application |
20120085257 |
Kind Code |
A1 |
Fu; Jyun-Horng |
April 12, 2012 |
SUPERCAVITATING PROJECTILE WITH REDUCED-DRAG CONTROL SURFACES
Abstract
The illustrative embodiment provides bumpers which are roughly
shaped like skis that face towards the air-water boundary of the
air cavity. When the projectile fishtails and one or more of the
bumpers come into contact with the air-water boundary, the water
imparts torque and a rebounding force to push the projectile
completely back into the air cavity. Furthermore, because the
bumpers are shaped roughly like skis and not like knives, the
bumpers do not penetrate the water or create unnecessary water
drag.
Inventors: |
Fu; Jyun-Horng;
(Centreville, VA) |
Assignee: |
Lockheed Martin Corporation
Bethesda
MD
|
Family ID: |
45921968 |
Appl. No.: |
12/399945 |
Filed: |
March 7, 2009 |
Current U.S.
Class: |
102/399 |
Current CPC
Class: |
Y02T 70/122 20130101;
Y02T 70/10 20130101; B63G 8/14 20130101; B63B 2001/382 20130101;
B63B 39/06 20130101; F42B 10/44 20130101; F42B 19/00 20130101 |
Class at
Publication: |
102/399 |
International
Class: |
F42B 15/22 20060101
F42B015/22 |
Claims
1.-10. (canceled)
11. A projectile comprising: a body; a cavitator connected to the
body, wherein the cavitator produces an air cavity when the
projectile travels through a water medium so that the projectile
substantially fits within the cavity, wherein the cavity has an
air/water boundary; and a first bumper connected to the body,
wherein the first bumper comprises a surface that is shaped and
arranged to cause the projectile to rebound from the air/water
boundary when the surface contacts the air/water boundary.
12-18. (canceled)
19. The projectile of claim 11 further comprising: a sensor that
senses a speed of the projectile; a controller that estimates a
shape of the cavity produced by the cavitator based on input from
the sensor.
20. The projectile of claim 19 further comprising an actuator that
extends or retracts the first bumper responsive to a command from
the controller.
21. The projectile of claim 11 further comprising three additional
bumpers for a total of four bumpers bumpers, wherein the three
additional bumpers are shaped and arranged to cause the projectile
to rebound from the air/water boundary when any one of the three
additional bumpers contacts the air/water boundary.
22. The projectile of claim 21 wherein an outer surface of each of
the bumpers has a shape that, when all such bumpers are considered
collectively, defines a frustum of an elliptical paraboloid.
23. (canceled)
24. A projectile comprising: a body; a cavitator connected to the
body, wherein the cavitator produces an air cavity when the
projectile travels through water so that the projectile
substantially fits within the cavity, wherein the cavity has an
air/water boundary; and a plurality of bumpers connected to the
body, wherein each bumper of the plurality thereof is shaped and
arranged to cause the projectile to rebound from the air/water
boundary upon contact of one or more of the bumpers with the
air/water boundary.
25. The projectile of claim 24 further comprising: a sensor that
senses a speed of the projectile; a controller that estimates a
shape of the cavity produced by the cavitator based on input from
the sensor.
26. The projectile of claim 25 further comprising at least one
actuator that extends or retracts each bumper responsive to a
command from the controller.
27. The projectile of claim 24 further comprising at least one
actuator that extends or retracts each bumper.
28. The projectile of claim 27 further comprising a controller that
transmits a command to the at least one actuator, wherein the
command directs the bumpers to retract when it is determined that
the air cavity is contracting.
29. The projectile of claim 27 further comprising a controller that
transmits a command to the at least one actuator, wherein the
command directs the bumpers to extend when it is determined that
the air cavity is expanding.
30. The projectile of claim 24 wherein, upon contact of one of the
bumpers with the air/water boundary, a first surface of the bumper
contacts the air/water boundary and that first surface has more
surface area than a second surface that is oriented substantially
normal to the first surface.
31. The projectile of claim 24 wherein an outer surface of each of
the bumpers has a shape that, when all such bumpers are considered
collectively, defines a frustum of an elliptical paraboloid.
32. A projectile comprising: a body; a cavitator connected to the
body, wherein the cavitator produces an air cavity when the
projectile travels through water so that the projectile
substantially fits within the cavity, wherein the cavity has an
air/water boundary; and a plurality of bumpers connected to the
body, wherein: (a) each bumper of the plurality thereof comprises a
surface that is shaped and arranged to cause the projectile to
rebound from the air/water boundary when the surface contacts the
air/water boundary; and (b) at least one actuator that extends or
retracts each bumper.
33. The projectile of claim 32 further comprising a controller,
wherein the controller transmits a command to the at least one
actuator, wherein the command directs the at least one actuator to
extend or retract the bumpers.
34. The projectile of claim 33 further comprising a sensor that
senses a speed of the projectile, wherein the sensor transmits, to
the controller, data relating to the sensed speed of
projectile.
35. The projectile of claim 34 wherein the controller determines
whether the air cavity is expanding or contracting based on the
data relating to the sensed speed of the projectile.
36. The projectile of claim 35 wherein the controller directs the
actuator to extend the bumpers when it is determined that the
cavity is expanding.
37. The projectile of claim 35 wherein the controller directs the
actuator to retract the bumpers when it is determined that the
cavity is contracting.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to supercavitating projectiles
in general, and, more particularly, to control surfaces for
supercavitating projectiles.
BACKGROUND OF THE INVENTION
[0002] A supercavitating underwater projectile can achieve speeds
of 150 knots, and, therefore, it is especially useful in naval
applications. A supercavitating underwater projectile achieves
these speeds because it comprises a special tip on its nose known
as a "cavitator." As the projectile travels through the water, the
cavitator contacts the water in such as way as to create many small
air bubbles. The small air bubbles then coalesce into one big air
bubble that is large enough to completely encompass the projectile.
The effect is that the projectile is traveling inside a giant air
bubble that is itself moving through the water.
[0003] FIG. 1 depicts a side view of the salient components of
supercavitating projectile 100 as known in the prior art inside
cavity 103. Supercavitating projectile 100 comprises projectile
body 101 and four prism-shaped fins 102-1, 102-2, 102-3, and 102-4
(not shown), which are equally spaced around body 101, and
cavitator 103.
[0004] As projectile 100 travels through the water, there is a
tendency for projectile 100 to swerve or fishtail, and the purpose
of fins 102-1 through 102-4 is to keep projectile 100 completely
inside air cavity 104. This minimizes the amount of projectile 100
which touches the water, which enables projectile 100 to go
fast.
SUMMARY OF THE INVENTION
[0005] One disadvantage of supercavitating underwater projectiles
in the prior art is that the prism-shaped fins tend to penetrate
the air-water boundary of the air cavity, which increases the water
drag on the projectile. Another disadvantage is that the position
of the fins is fixed and does not adjust to changes in the shape of
the cavity that are caused by changes in the speed of the
projectile.
[0006] The present invention enables a supercavitating underwater
projectile to stay within the air cavity without some of the costs
and disadvantages for doing so in the prior art. For example, the
illustrative embodiment provides bumpers which are roughly shaped
like skis that face towards the air-water boundary of the air
cavity. When the projectile fishtails and one or more of the
bumpers come into contact with the air-water boundary, the water
imparts torque and a rebounding force to push the projectile
completely back into the air cavity. Furthermore, because the
bumpers are shaped roughly like skis and not like knives, the
bumpers do not penetrate the water or create unnecessary water
drag.
[0007] Furthermore, the illustrative embodiment comprises an
actuator for changing the positioning of the bumpers based on the
speed of the projectile and a cavity-shape model.
[0008] The illustrative embodiment comprises: a projectile body
capable of creating a air cavity inside water, wherein the air
cavity is defined by a air-water boundary; and a first ski-shaped
bumper connected to the projectile body, wherein the bottom of the
first ski-shaped bumper faces the air-water boundary of the air
cavity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 depicts a side view of the salient components of
supercavitating projectile 100 as known in the prior art inside
cavity 103.
[0010] FIGS. 2A and 2B depict left side and front views,
respectively, of the salient components of supercavitating
projectile 200 in accordance with the illustrative embodiment.
[0011] FIGS. 3A and 3B depicts left side and front views,
respectively of the salient components of supercavitating
projectile 200 with respect to elliptic paraboloid 301 and frustum
302 of elliptic paraboloid 301.
[0012] FIG. 4 depicts a cut-away view, along line A-A in FIG. 2B,
of the salient components of supercavitating projectile 200.
[0013] FIG. 5 depicts longitudinal axis 501 of supercavitating
projectile 200 and line 502, which is perpendicular to longitudinal
axis 501.
DETAILED DESCRIPTION
[0014] FIGS. 2A and 2B depict left side and front views,
respectively, of the salient components of supercavitating
projectile 200 in accordance with the illustrative embodiment.
FIGS. 3A and 3B depicts left side and front views, respectively of
the salient components of supercavitating projectile 200 with
respect to elliptic paraboloid 301 and frustum 302 of elliptic
paraboloid 301. FIG. 4 depicts a cut-away view, along line A-A in
FIG. 2B, of the salient components of supercavitating projectile
200. FIG. 5 depicts longitudinal axis 501 of supercavitating
projectile 200 and line 502, which is perpendicular to longitudinal
axis 501.
[0015] Supercavitating projectile 200 comprises: projectile body
201, bumpers 202-1 through 202-4, bumper struts, 203-1 through
203-4, cavitator 204, sensor 401, controller 402, and actuator
403.
[0016] Although supercavitating projectile 200 comprises four
bumpers and four struts, it will be clear to those skilled in the
art, after reading this disclosure, how to make and use alternative
embodiments of the present invention which comprise any number of
bumpers and struts.
[0017] Projectile body 201 is a non-explosive, propelled object,
such as a bullet, for imparting kinetic energy to a target. It will
be clear to those skilled in the art, after reading this
disclosure, how to make and use alternative embodiments of the
present invention in which projectile body 201 is an explosive
object. Furthermore, it will be clear to those skilled in the art,
after reading this disclosure, how to make and use alternative
embodiments of the present invention in which projectile body 201
is a self-propelled object, such as a missile, rocket, or
torpedo.
[0018] Bumper 202-i, wherein i.epsilon.{1, 2, 3, 4}, is a
ski-shaped structure for keeping projectile body 201 within air
cavity 205 and minimize the projectiles yaw angle relative to its
trajectory. The purpose of bumper 202-i is to generate torque and
rebounding forces when projectile body 201 fishtails and bumper
202-i contacts the air-water boundary of air cavity 205.
[0019] The sum of the outer surfaces of bumpers 202-1 through 202-4
are shaped so as to suggest a frustum 302 of elliptic paraboloid
301, as depicted in FIGS. 3A and 3B, which frustum is designed to
conform to the shape of air cavity 205. The vertex of the
elliptical paraboloid is coincident with cavitator 204. It will be
clear to those skilled in the art, after reading this disclosure,
how to make and use alternative embodiments of the present
invention in which the bumpers suggest another shape, such as for
example, and without limitation, a frustum of a conic section, a
box, a pyramid, sphere, or polyhedron. The parabolic shape of
bumper 202-i is intended to present a low-drag surface to the
air-water boundary of air cavity 204, in contrast to the high-drag
surface of the bumpers in the prior art. In accordance with the
illustrative embodiment, the shape and orientation of bumper 202-i
is such that bumper 202-i has more surface area facing in parallel
with line 502 than perpendicularly to the line (i.e., in parallel
with line 503) as depicted in FIG. 5.
[0020] Strut 203-i is a rigid member that structurally connects
bumper 202-i to actuator 403 within projectile body 201. It will be
clear to those skilled in the art, how to make and use strut
203-i.
[0021] Cavitator 204 is a tip, as is well-known in the prior art,
on the nose of projectile body 201 that contacts the water in front
of supercavitating projectile 200 in such as way as to create many
small air bubbles. The small air bubbles then coalesce into one big
air bubble that is large enough to completely encompass the
supercavitating projectile 200. It will be clear to those skilled
in the art how to make and use cavitator 204.
[0022] Sensor 401 is a mechanism for detecting the speed of
supercavitating projectile 200 through the water and for
transmitting an indication of that speed to controller 402. It will
be clear to those skilled in the art how to make and use controller
402.
[0023] Controller 402 is electronics for estimating the shape of
air cavity 205 based on the speed measurement from sensor 401 and
for controlling actuator 403 to position bumpers 202-1 through
202-4 so that they are in the correct position with respect to the
air-water boundary of air cavity 204. To do this, controller 402
uses a cavity-shape model based on the speed with which
supercavitating projectile 200 is moving through the water. For
example, when controller 402 determines that air cavity 205 is
expanding, controller 402 directs actuator 403 to extend bumpers
202-1 through 202-4, but when controller 402 determines that air
cavity 205 is contracting, controller 402 directs actuator 403 to
retract bumpers 202-1 through 204-4.
[0024] Actuator 403 is a mechanism for extending and retracting
bumpers 202-1 through 202-4 under the direction of controller 402.
It will be clear to those skilled in the art how to make and use
actuator 204.
[0025] It is to be understood that the disclosure teaches just one
example of the illustrative embodiment and that many variations of
the invention can easily be devised by those skilled in the art
after reading this disclosure and that the scope of the present
invention is to be determined by the following claims.
* * * * *