U.S. patent application number 09/785732 was filed with the patent office on 2001-10-25 for deployable net for control of watercraft.
Invention is credited to Gessner, Kevin, Swartout, Terry L..
Application Number | 20010032577 09/785732 |
Document ID | / |
Family ID | 22673449 |
Filed Date | 2001-10-25 |
United States Patent
Application |
20010032577 |
Kind Code |
A1 |
Swartout, Terry L. ; et
al. |
October 25, 2001 |
Deployable net for control of watercraft
Abstract
A system and method for the capture of a target surface vessel
by a second vessel. The system includes an initially stowed
deployable net, means for deploying the net, a tether coupled to
the net, and a winch for drawing in the tether to pull the target
vessel toward the second vessel.
Inventors: |
Swartout, Terry L.; (Largo,
FL) ; Gessner, Kevin; (Midlothian, VA) |
Correspondence
Address: |
WIGGIN & DANA LLP
ATTENTION: PATENT DOCKETING
ONE CENTURY TOWER, P.O. BOX 1832
NEW HAVEN
CT
06508-1832
US
|
Family ID: |
22673449 |
Appl. No.: |
09/785732 |
Filed: |
February 16, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60183587 |
Feb 18, 2000 |
|
|
|
Current U.S.
Class: |
114/254 ;
102/356; 114/382 |
Current CPC
Class: |
F41H 13/0006 20130101;
B63G 13/00 20130101; B63B 21/56 20130101 |
Class at
Publication: |
114/254 ;
114/382; 102/356 |
International
Class: |
B63B 035/00 |
Claims
What is claimed is:
1. A system for permitting a first surface vessel (50) to capture a
second surface vessel (52) comprising: a net (56) having an initial
stowed condition; a launcher (24) for projecting the net from the
stowed condition to a deployed condition ensnaring the second
vessel at a first location; a winch (64); and at least one tension
line (62) coupling the net to the winch.
2. The device of claim 1 wherein the launcher comprises: first and
second chemical rockets (72A, 72B); and a harness system (70A, 70B)
coupling the first and second rockets to a distal portion of the
net.
3. The device of claim 2 wherein the net generally increases in
width from a proximal portion to a distal portion in an unfurled
condition.
4. The device of claim 3 wherein the harness includes left and
right portions, coupled to the first and second rockets
respectively and distributing force applied by said rockets over a
substantial portion of a net leading edge (60).
5. The device of claim 4 wherein the net leading edge bears a
plurality of weights (80) having a specific gravity substantially
in excess of 1, effective to cause sinking of a distal portion of
the net.
6. The device of claim 1 wherein the net carries no explosive
material.
7. The device of claim 6 wherein the net is reusable after
deployment.
8. The device of claim 7 wherein in its stowed condition, the net
is suspended within a storage container.
9. The device of claim 1 wherein the net comprises aramid fiber
reinforced with stainless steel cable.
10. A method for the capture of a target surface vessel by a second
vessel comprising: providing on the second vessel a deployable net
system including: an initially stowed net; at least two chemical
rockets coupled to the net a winch; and a tension line coupling the
net to the winch; launching the two chemical rockets to deploy the
net over the target vessel in a first location; and causing the
winch to draw in the tension line and pull the target vessel toward
the second vessel.
11. The method of claim 10 further comprising: permitting a portion
of the net located distally of the target vessel to sink so as to
enhance entanglement of the target vessel in the net; permitting
the target vessel to move from the first position and override a
portion of the sunken portion of the net; and permitting the
overridden portion of the net to entangle and stop a propeller of
the target vessel.
12. The method of claim 10 further comprising: returning the net to
its stowed condition; unwinding the tension line from the winch;
and replacing or refueling the rockets.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This patent application claims priority of U.S. Provisional
Patent Application Ser. No. 60/183,587 entitled "DEPLOYABLE NET FOR
CONTROL OF WATERCRAFT" that was filed on Feb. 18, 2000, the
disclosure of which is incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] (1) Field of the Invention
[0003] This invention relates to water-borne vessels, and more
particularly to capturing of one vessel by another.
[0004] (2) Description of the Related Art
[0005] Rocket-deployed net devices have been used for
neutralization of mines in shallow water during amphibious assault
operations. General Dynamics Ordnance and Tactical Systems, Inc.
(formerly Primex Technologies, Inc.) has developed such a system
utilizing distributed explosive technology (DET). Each
self-contained DET system includes the distributed explosive net
and the associated solid propellant rocket motors, a fire control
system, launch rails, and a shipping and storage container.
BRIEF SUMMARY OF THE INVENTION
[0006] We have adapted this mine neutralization technology to use
in capturing vessels. In one aspect, the invention is directed to a
system for permitting a first surface vessel to capture a second
surface vessel. The system is mounted on the first surface vessel
and includes a net having an initial stowed condition. A launcher
projects the net from the stowed condition to a deployed condition
ensnaring the second vessel at a first location. A winch is coupled
to the net via a tether to permit the net to draw the ensnared
second vessel from the first location toward a location of the
second vessel. Such locations may be either absolute or relative
depending upon the particular conditions involved.
[0007] In implementations of the invention, the launcher may
include first and second chemical rockets such as solid propellant
rockets. The rockets may be coupled to a distal portion of the net
via a harness system. The net may generally increase in width from
a proximal portion to a distal portion when the net is in an
unfurled condition. The harness may include left and right portions
respectively coupled to the first and second rockets and
distributing force supplied by the rockets over a substantial
portion of a net leading edge.
[0008] The net leading edge may bear a plurality of weights having
a specific gravity in excess of one and effective to cause sinking
of a distal portion of the net. Exemplary material for the weights
includes lead and various nontoxic lead substitutes. For nonlethal
use, the net preferably carries no explosive material and is
advantageously reusable after deployment. More aggressive systems
may have explosive or other offensive components.
[0009] In another aspect, the invention is directed to a method for
the capture of a target surface vessel by a second vessel. An
aforementioned net system is provided on the second vessel. The
rockets are launched to deploy the net over the target vessel in a
first location. The winch is caused to draw in the tether then pull
the target vessel toward the second vessel. The method may include
permitting a portion of the net located distally of the target
vessel in the first location to sink so as to enhance entanglement
of the target vessel in the net. The method may include permitting
the target vessel to move from the first position and override a
portion of the sunken portion of the net. The method may include
permitting the overridden portion of the net to entangle and stop a
propeller of the target vessel. The method may further include
returning the net to its stowed condition, unwinding the tether
from the winch, and replacing or refueling the rockets so as to
permit reuse of the system.
[0010] The details of one or more embodiments of the invention are
set forth in the accompanying drawings and the description below.
Other features, objects, and advantages of the invention will be
apparent from the description and drawings, and from the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a functional diagram of an exemplary vessel
capture system.
[0012] FIG. 2 is an operational sequence flow chart of an exemplary
vessel capture system.
[0013] FIG. 3 is a view of structural portions of an exemplary
storage and shipping container which may be adapted for use with a
deployable net.
[0014] FIG. 4 is a view of a net in an intermediate stage of
deployment from a command vessel over a target vessel.
[0015] FIG. 5 is a schematic time lapse of various intermediate
stages of deployment of an exemplary net.
[0016] FIG. 6 is a top view of an intermediate stage in deployment
of a net over a target vessel.
[0017] Like reference numbers and designations in the various
drawings indicate like elements.
DETAILED DESCRIPTION
[0018] FIG. 1 shows a functional diagram of a system 20. The system
20 includes a containment net 22, a launch rail system 24, a fire
control system (FCS) 26, a propulsion system 28, a craft interface
kit 30, a storage and shipping container 32, a restraint system 34,
and spare parts and logistic support equipment 36.
[0019] The craft interface kit contains the hardware necessary to
install the system on a particular command or capture vessel 50
(FIG. 4). FIG. 4 also shows a target vessel 52 which is typically
much smaller than the command vessel. FIG. 6 shows the net 22
deployed over the target vessel by the command vessel. The
exemplary unfurled net 22 has a main net portion 56 diverging
distally in a generally triangular form from a proximal vertex 58
to a distal leading edge 60. A tether or tension line 62 in the
restraint system connects the net to a winch 64 which may be
electrically powered and may be integrated with or located adjacent
to the launch rail system.
[0020] At its leading edge, the main net portion is connected to
left and right harness wings 70A and 70B. The harness wings contain
a number of elements extending from the net leading edge to an
associated left and right rocket motor 72A and 72B. At various
locations along the net leading edge, an array of weights 80 may be
provided.
[0021] An exemplary operational sequence is shown in FIG. 2. As
shown, after the target vessel is encountered and identified, the
fire control system (FCS) is activated. The FCS provides feedback
to the command vessel's pilot to enable him to position his vessel
in position in order to launch the VCS. The FCS provides data such
as required command vessel heading and speed. Once the command to
launch is provided by the pilot, the fire control system will
automatically fire the rocket motors when proper launch parameters
are met, ensuring target vessel envelopment. The traveling rockets
extract the net and deliver it over the target vessel. The net
envelopes the target vessel and, preferably ensnares the vessel and
entangles its propellers to further disable the vessel. The winch
may then be activated to draw the target vessel toward the command
vessel to allow for boarding or other actions.
[0022] By flying in slightly divergent paths, the rocket motors,
via the harnesses, spread the net laterally in addition to
longitudinally (FIG. 6). Exemplary details of vessel envelopment
are disclosed in the sequence view of FIG. 5. The view of FIG. 5
reflects an exemplary frame of reference of the command with both
the command and target vessels moving at a given velocity from left
to right. The rocket motors are collectively referenced as 72 and
the harness wings as 70. Of the six illustrated stages, shown by
numerals 100, 101, 102, 103, 104 and 105 referencing rocket motor
position, the first four involve progressive stages in rocket
flight propelling the net. The fifth stage shows the rocket motors
falling into the water. Due to the density of the rocket motors and
to the density of weights on the harness connecting the rockets to
the net or on a distal portion of the net, the net sinks, allowing
the velocity of the target vessel to cause the target vessel to
override the net as shown in the sixth stage. Once overridden, the
net may become entangled in the target vessel's propellers, causing
shutdown of the target vessel's engine.
[0023] The containment net is preferably constructed of
lightweight, high-strength materials to enable rocket motor or
ballistic slug deployment and vessel capture and to be capable of
enveloping the target vessel and preventing target vessel
propulsion. The net size may be optimized for target vessel
capture. The net, being significantly larger than the target vessel
is deployed over such vessel. The ballistically dense rocket motors
will sink upon impacting the water. This causes the forward section
of the harness and array to hang down in the water column. As the
target vessel attempts to escape, the harness lines and array will
then become wrapped around the vessel's hull and, if present,
tangled in the propeller. This will cause the propeller to cease
motion, rendering the target vessel unable to continue motion. The
net size will advantageously be a minimum of 250 ft (76 m) wide by
250 ft (76 m) long and will likely have a weight of 1000 to 3000
lbs (450 to 1360 kg), depending on target vessel requirements. Nets
of this size have been successfully deployed from surface craft in
distances in excess of 1500 ft (460 m).
[0024] Exemplary material for the net is aramid fiber reinforced
with a core of stainless steel cable. The cable provides the net
with additional toughness to resist abrasion and damage such as
that caused by entanglement with a target vessel propeller. The
tether material may be aramid fiber or similarly reinforced aramid
fiber or may be formed of a relatively elastic material.
[0025] The integrated launch rail system may be used to support the
rocket motors prior to launch and provide for desired rocket motor
path during extraction. This system may provide for the adjustment
of quadrant elevation and azimuth angle for required mission
settings. The launch rail components will advantageously be suited
for long-term exposure to salt air. The reusable launch rail system
will advantageously be provided with a complete inventory of spare
parts. Each launch rail may be an exemplary 5 feet (1.5 m) long and
is supported by a framework that interfaces with the shipping
container and craft interface kit.
[0026] The fire control system will advantageously provide the
capability to accurately deploy the containment net from the
command vessel while experiencing pitch, roll, yaw, heave, sway,
and forward motion. Using sophisticated motion platforms for
testing and algorithm development, computer codes, and
instrumentation, this type of fire control system has been
demonstrated as an effective accurate means of deploying nets using
unguided solid propellant rocket motors. The system will rely upon
motion sensors, tailored deployment algorithms, and a display unit
for the command vessel. The fire control system will advantageously
be self-supporting and will not rely on command ship resources
other than electrical power.
[0027] Depending on desired range, air guns or solid propellant
rocket motors can be used to extract the net and delivery it over
the target vessel. MK 22 MOD 4 rocket motors may be used at least
for purposes of a demonstration test. These motors are fully
qualified for use on US Navy vessels and have passed all required
explosive safety tests. Having been used to extract and deploy
nets, these rocket motors are a low-risk approach to net
propulsion. They can be safety operated in temperatures ranging
from -40.degree. to +120.degree. F. (-40.degree. to +49.degree.
C.). Two launch lugs on each motor interface with the launch rail
system. The rocket motors will provide adequate thrust to extract
the net at speeds typically in excess of 200 ft/sec (61 m/sec). The
entire event, from extraction to deployment over the target vessel
is expected to take no more than 5 seconds.
[0028] The craft interface kit (CIK) provides for all required
interfaces between the command vessel and the VCS. It includes
mounting hardware, electrical connections, and special tools (if
any).
[0029] The deployable portions of the VCS are advantageously loaded
into the storage and shipping container providing protection during
transportation and storage. It also serves as the support structure
from which the net is deployed. Environmental protection is
provided in this reusable container. The net is hung from the roof
of the container. The installation loops are disengaged during net
extraction and allow for high-rate reliable deployment. The SSC
preferably weighs approximately 500 lbs (227 kg) and is
approximately 8.times.5.times.4 ft (2.4.times.1.5.times.1.2 m)
high.
[0030] While the containment net alone will preferably be able to
limit the target vessel's ability to navigate, a winch system is
preferably used to provide additional control. A tension line or
tether will be attached to the aft (proximal) end of the
containment net. This tether will be attached to a winch installed
on the command vessel. As desired, the target vessel can be winched
toward the command vessel for subsequent boarding or other
operations.
[0031] Target vessel attributes such as weight, length, speed, and
depth considerations must be understood and characterized and will
influence any particular implementation. Target vessel studies will
allow development of a system requirements document (SRD) to be
used in optimization studies to assure that the system provides
required functionality for the particular application (types of
target and capture vessels, speeds and water conditions, etc.). The
SRD may provide a roadmap for follow-on analysis, design
optimization, and test efforts.
[0032] Understanding and predicting the dynamic loading
characteristics of deployable VCS components is advantageous before
a structurally appropriate design is developed. In addition, the
inter-relationship between important parameters such as range, net
spread at impact, the effects of craft motion on accuracy, quadrant
elevation, azimuth angle, net weight, and rocket motor thrust must
be clearly understood and studied. Computer analysis tools have
been developed for solving such deployment analysis problems.
[0033] Various rocket motor-deployed mine counter measures (MCM)
Systems have been developed over the past ten years. In support of
these efforts, computer simulation techniques have been developed
and implemented.
[0034] The Automatic Dynamic Analysis of Mechanical Systems (ADAMS)
code (Mechanical Dynamics, Inc., Ann Arbor, Mich.) may be used to
analyze all important deployment characteristics. The ADAMS code
has been used to model the deployment characteristics of several
net systems with great success. A six degree of freedom
representation of the VCS may be used to solve for component
acceleration, velocity, position, and internal loading during,
deployment. A verified baseline net deployment model may be made
available for the minor modifications as required by the target
vessel set. This baseline model may also be used to conduct
parametric studies to support fire control algorithm development.
This model is believed capable of accommodating all environmental
conditions such as heave, sway, pitch, roll, yaw, and wind. The
rocket motor, containment net, winch system, connectors, and
harness, may be represented using the ADAMS 6-DOF code. The bridle
may be represented by a number of bridle segments. Special
attention may be paid to modeling the harness and high load areas
to allow for accurate load and acceleration predictions at these
components. The rocket motor and bridle representation may allow
for rocket motor rotation and translation in response to loads
exerted by the payload. Since the payload exerts rotational forces
that induce rocket motor pitching and yawing, this representation
is useful to accurately predict system trajectory. The simulated
launch configuration will preferably match one-for-one the actual
pre-launch configuration.
[0035] ADAMS models a mechanical system by solving the following
first order Euler-Lagrange equations:
[0036] where:
m.sub.ia.sub.i-Fi-.SIGMA..sup.m.sub.j=1Rfj.sup..PHI..sub.xi=0
dxi/dt-V.sub.i=0
.PHI.j=0
[0037] i=1,2,3 . . . n
[0038] m.sub.1=mass of the ith coordinate
[0039] x.sub.1=displacement of ith coordinate
[0040] F.sub.i=sum of applied forces acting on the ith
coordinate
[0041] Rf.sub.j=reaction force for the jth coordinate
[0042] j=1,2,3 . . . m
[0043] a.sub.j=acceleration
[0044] V.sub.i=velocity
[0045] Initial conditions, backward differencing formula (BDF), and
the Euler-Lagrange equations define the initial value problem (IVP)
in ADAMS. ADAMS employs a multi-step predictor-corrector method to
solve the IVP that improves accuracy made by explicit methods
alone, such as the Runge-Kutta method of four. With the
predictor-corrector method, an explicit method predicts an
approximation to the solution and implicit method corrects this
prediction. Additionally, ADAMS employs a variable step-size
algorithm to further reduce integration error.
[0046] The predictor applies a BDF to each unknown in the system to
provide an initial guess for the corrector. The corrector is a
modified Newton-Raphson algorithm that solves the Euler-Lagrange
equations and the BDF equations. The self-formulating ADAMS code
requires the input of mass properties, dynamic material properties,
initial position, and aerodynamic properties.
[0047] A 3-D aerodynamic representation of the system may be used
to predict flight characteristics of the system. Aerodynamic lift
and drag as a function of angle of attack and velocity will be
included. The aerodynamic coefficients of the grenades, rocket
motor, and fuzes will be based on theoretical data unless wind
tunnel data is available.
[0048] Aerodynamic forces will be implemented assuming the
following:
Drag=1/2Cd .rho.area V.sup.2
Lift=1/2Cl .rho.area V.sup.2
[0049] where:
[0050] Drag=force normal to apparent velocity (lbf or n)
[0051] Lift=force tangent to apparent velocity (lbf or n)
[0052] Cd coefficient of drag, as a function of angle of attack
[0053] Cl coefficient of lift, as a function of angle of attack
[0054] .pi.=air density (slug/ft.sup.3 or kg/m.sup.3)
[0055] area=reference area (ft.sup.2 or m.sup.2)
[0056] V=apparent velocity (ft/sec or m/s)
[0057] Time varying rocket motor performance may be accounted for
in the VCS deployment model. Worst-case rocket motor performance,
yielding the highest dynamic loads, may be assumed. Rocket motor
performance data may be taken from static firings and theoretical
calculations.
[0058] Results from this analysis effort may also be used to
develop fire control algorithms.
[0059] The greatest challenge in deploying a net from a small
surface craft is accounting for potential craft motion while the
rocket motors are travelling along the launch rails. Once the
rocket motors have separated from the launch rails, craft motion
has little impact on system trajectory. The fire control will
advantageously incorporate a system of sensing craft 6-DOF motion
and provisions made to account for the impact of launch rail
position and motion effects on rocket motor trajectory.
[0060] One or more embodiments of the present invention have been
described. Nevertheless, it will be understood that various
modifications may be made without departing from the spirit and
scope of the invention. For example, the nature of the target
vessel and its capture environment will significantly influence
preferred construction details. Accordingly, other embodiments are
within the scope of the following claims.
* * * * *