U.S. patent application number 10/243417 was filed with the patent office on 2004-03-18 for passive aerial protection system.
Invention is credited to Hoffman, Louis J., Lisa, Steven G..
Application Number | 20040050014 10/243417 |
Document ID | / |
Family ID | 31991634 |
Filed Date | 2004-03-18 |
United States Patent
Application |
20040050014 |
Kind Code |
A1 |
Lisa, Steven G. ; et
al. |
March 18, 2004 |
Passive aerial protection system
Abstract
A disclosed aerial protection system relies on the principle of
disrupting horizontal flight of an attacking aircraft toward the
facility it protects. By disrupting the aircraft's flight, the
system helps reduce concentration of any impact and fire from the
aircraft. The system includes a number of support masts disposed
about an area of terrain enclosing a facility, and a plurality of
cable groups that each include a multitude of cables. The cables in
each group are coupled to an adjacent pair of the support masts and
extend substantially coplanar with the support masts. The cables
are separated from each other at a spacing that is comparable to
(and preferably slightly less than) a typical wingspan of an
aircraft from a class of interest. Numerous variations and methods
are also disclosed.
Inventors: |
Lisa, Steven G.; (Paradise
Valley, AZ) ; Hoffman, Louis J.; (Scottsdale,
AZ) |
Correspondence
Address: |
Louis J. Hoffman
LOUIS J. HOFFMAN, P.C.
Suite 300
14614 North Kierland Boulevard
Scottsdale
AZ
85254
US
|
Family ID: |
31991634 |
Appl. No.: |
10/243417 |
Filed: |
September 12, 2002 |
Current U.S.
Class: |
52/741.3 ;
52/651.11; 52/654.1 |
Current CPC
Class: |
E04H 9/04 20130101; F41H
11/04 20130101 |
Class at
Publication: |
052/741.3 ;
052/651.11; 052/654.1 |
International
Class: |
E04H 012/00; E04B
001/00 |
Claims
What is claimed is:
1. A system for protecting a facility against aerial attack,
comprising: (a) a multitude of vertical support masts disposed
about an area of terrain enclosing a facility; and (b) a plurality
of cable groups that each include a multitude of cables, wherein
for each group, a plurality of the cables are coupled to and
substantially coplanar with an adjacent pair of the support masts;
(c) wherein the cables are spaced to disrupt horizontal flight of
an aircraft toward the facility.
2. The system of claim 1 wherein the cables of each cable group are
separated from each other by a horizontal spacing comparable to a
typical wingspan of an aircraft from a class of interest.
3. The system of claim 2 wherein the cables of each cable group are
separated from each other by a horizontal spacing in the range of
about 50-200% of the typical wingspan of an aircraft from a class
of interest.
4. The system of claim 3 wherein the cables of each cable group are
separated from each other by a horizontal spacing of about 75% of
the typical wingspan of an aircraft from a class of interest.
5. The system of claim 1 wherein the multitude of masts are
arranged in a polygonal arrangement and include at least four
support masts.
6. The system of claim 1 further comprising a plurality of
partially buried concrete base structures, wherein each one of the
support masts is embedded in a respective one of the base
structures.
7. The system of claim 1 further comprising a plurality of
partially buried concrete anchors, each disposed between an
adjacent pair of the support masts and each connecting to some of
the cables of the cable group.
Description
BACKGROUND OF THE INVENTION
[0001] On Sep. 11, 2001, terrorists destroyed the World Trade
Center towers in New York City by suicidally flying fuel-laden
airliners into them at high speed. It is widely believed that the
towers' ultimate demise resulted not so much from the impact of the
aircraft but from the intense heat generated by the huge amounts of
jet fuel they carried. The volatility of the fuel combined with its
massive concentration in a relatively confined region resulted in
an inferno that fatally weakened the towers' structural members.
Fireproofed steel loses half its strength upon reaching a
temperature of 1,100.degree. F., and the concentrated fireball of
burning fuel probably subjected the towers' structural members to
much higher temperatures than that.
[0002] Whether primarily responsible for the collapse or not, the
impact of the aircraft was heightened, too, by a deadly combination
of impact force and concentration of that force. The towers were
designed to withstand 100 mph winds, which would subject each story
of the towers to distributed force of perhaps a hundred thousand
pounds. But each tower suffered tremendous, perhaps fatal damage
from the concentrated, bullet-like impact of an airliner's fuselage
slicing into it "head on" at high speed.
[0003] After the September 11 terrorist attacks, the U.S. Nuclear
Regulatory Commission admitted that it did not specifically
contemplate attacks by the type of aircraft used by the terrorists.
Conventional defense systems had targeted missiles and planes of a
military aggressor, not civilian airliners piloted by suicidal
terrorists.
[0004] The danger of similar attacks to occurring against nuclear
installations, as well as government buildings, ammunition
stockpiles, and other sensitive facilities, has been widely
observed. Significant political and logistic difficulties arise
with conventional active (i.e., "shooting") defense against such
attacks. What is needed, then, is a simple, passive way to protect
sensitive facilities against the most devastating, concentrated
effects of an aerial attack.
SUMMARY OF THE INVENTION
[0005] An aerial protection system according to various aspects of
the present invention relies on the principle of disrupting
horizontal flight of an attacking aircraft toward the facility it
protects. By disrupting the aircraft's flight, the system helps
reduce concentration of any impact and fire from the aircraft.
[0006] The system includes a number of support masts disposed about
an area of terrain sufficiently large to enclose the facility, and
a plurality of cable groups that each include a multitude of
cables, i.e., more than just a plurality. The cables in each group
are coupled to an adjacent pair of the support masts, extending
substantially coplanar with the support masts. The cables are
separated from each other at a spacing that is comparable to (and
preferably slightly less than) a typical wingspan of an aircraft
from a class of interest.
[0007] An airliner hitting all but the strongest cables at
near-cruising speed is unlikely to be entirely stopped by those
cables. Advantageously, however, the inventive system can
substantially reduce damage to the protected facility by disrupting
the aircraft's flight before impact. For example, when an aircraft
hits one or more cables suspended in accordance with various
aspects of the invention, it may lose a wing, yaw violently, veer
off course, or any combination of those disruptive actions. In
addition, the aircraft may well burst into flame or break up upon
impact with the cable. As used herein, the term "disrupt" includes
any action that alters the flight of an attacking aircraft in a way
that reduces damage caused by its impact or prevents the impact
altogether.
[0008] The effect of this disruption is to lessen the concentration
of impact and fuel should the aircraft nevertheless strike the
protected facility. If a wing separates from the craft, the wing
and remaining portions of the aircraft can be expected to hit the
facility at somewhat separated points, distributing the impact and
separating the burning fuel from the impact point. The fuselage can
be expected to have less damaging impact on the facility if it has
been forced to yaw significantly from a bullet-like "head on"
orientation. Concentration of fire inside the facility is
substantially lower from an aircraft that has exploded or begun
burning violently before hitting the facility than from one that
slices into the facility with a full load of fuel waiting in its
tanks. Remaining fuel would also probably strike the facility, but
in a less concentrated way.
[0009] The above summary does not include an exhaustive list of all
aspects of the present invention. Indeed, the inventor contemplates
that the invention includes all systems and methods that can be
practiced from all suitable combinations of the various aspects
summarized above, as well as those disclosed in the detailed
description below and particularly pointed out in the claims filed
with the application. Such combinations have particular advantages
not specifically recited in the above summary.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Various embodiments of the present invention are described
below with reference to the drawings, wherein like designations
denote like elements.
[0011] FIG. 1 is a perspective view of an aerial protection system
according to various aspects of the invention having four masts in
a square arrangement.
[0012] FIG. 2 is a perspective view of an aerial protection system
according to various aspects of the invention having six masts in a
hexahedral arrangement.
DESCRIPTION OF PREFERRED EXEMPLARY EMBODIMENTS
[0013] A system for protecting a facility against aerial attack
according to various aspects of the present invention limits damage
to the facility from an attacking aircraft by erecting a barrier
around the facility using masts and cables. As may be better
understood with reference to FIG. 1, for example, system 100
surrounds a nuclear facility 110 with cables suspended from a
square arrangement of support masts 122-128 around facility 110. As
discussed above, and also below with reference to an example
involving an attacking aircraft 150, system 100 substantially
reduces damage to facility 110 by disrupting the flight of aircraft
150 before impact.
[0014] Each adjacent pair of masts 122-124, 124-126, 126-128, and
128-122 in system 100 supports a group of cables that extend
substantially coplanar with the support masts of that pair. For
clarity of illustration, FIG. 1 fully depicts just one of the four
cable groups of system 100, i.e., the one supported by adjacent
masts 122-124. That group includes a top supporting cable 130,
which suspends substantially vertical cables 142, 144, and others
not referenced by number in FIG. 1. Intermediate horizontal support
cables (optional) are also shown, such as cable 160 in FIG. 1. Only
the top supporting cables of the other groups in system 100 are
depicted in FIG. 1. These are: for mast pair 124-126, cable 132;
for mast pair 126-128, cable 134; and for mast pair 128-122, cable
136.
[0015] The masts may be arranged in any closed or semi-closed
shape. A semi-closed shape takes advantage of terrain features such
as a cliff adjacent to the facility, with the masts and cable
groups shielding other directions. A closed arrangement surrounds
the facility but may follow an irregular path, such as to avoid
obstacles or other nearby property. A polygonal arrangement of
support masts is one in which the masts define vertices of a
polygon-shaped border, i.e., a closed border bounded by straight
line segments. Each line segment of the border connects adjacent
masts. Masts in a polygonal arrangement need not be connected by
lines of any actual polygon, although it can be expected that such
will often be the case. For example, the masts of exemplary system
100 (FIG. 1) are indeed connected by lines of a regular polygon,
i.e., a square, in the form of top suspending wires 130, 132, 134,
and 136.
[0016] The cables in each group are separated from each other by a
spacing that is comparable to a typical wingspan of an aircraft
from a class of interest, preferably a bit less than the typical
wingspan. For example, cables 142-144 for mast pair 122-124 are
separated from each other by about the wingspan of attacking
aircraft 150, and have about the same separation from other
adjacent cables.
[0017] The length of a typical wingspan depends on the class of
aircraft being considered, but is certainly no less than about 15
feet (for small pleaure aircraft) and no greater than about 150
feet (for commercial airliners). In exemplary system 100, protected
facility 110 is a nuclear plant that has enough structural
integrity to withstand attack from small commuter aircraft. Thus,
cables 142, 144, etc. can be separated by a spacing comparable to
the typical wingspan of a commercial airliner, for example
somewhere between 100-200 feet. A fairly small spacing that is
comparable to a typical wingspan (e.g., 50 feet) can be employed to
virtually guarantee a collision between a horizontally attacking
airliner and at least one cable. A fairly large spacing, still
comparable to a typical wingspan (e.g., 150 feet), can be employed
instead to maintain a reasonable likelihood of collision while
minimizing the number of cables that need to be suspended.
[0018] The term "comparable" is generally employed herein to
indicate that two dimensions are functionally equivalent, i.e.,
that no significant change in performance would be expected between
systems that differ only in the dimensions considered comparable.
For example, one-foot cable spacing would certainly not be
considered comparable to 100-foot spacing in any sense of the word
because cables so closely spaced would require a tremendous amount
of support structure while offering no significant functional
advantage over cables spaced 100 feet apart. But 75- or 125-foot
spacing is clearly comparable to 100-foot spacing because the
difference would entail no significant change in support structure
or likelihood of collision. In accordance with a more particular
aspect of the invention, the term "comparable" can be understood as
simply indicating less than about a two-to-one difference between
two measurements.
[0019] The spacing of principal concern is measured along a
horizontal axis, because aircraft typically have a head-on
cross-section that is much wider (through the wingspan) than it is
high. Nonetheless, spacing along the vertical axis is preferably
kept comparable to that along the horizontal axis to prevent
attackers from rapidly rolling their aircraft to a sideways
orientation to pass through the "net" of cables. In system 100, for
example, horizontal spacing between vertically suspended cables
142, 144, etc. is about half the vertical spacing between top
supporting cable 130 and a midpoint horizontal cable 160.
[0020] Another exemplary system 200, which may be better understood
with reference to FIG. 2, employs a hexagonal arrangement of
support masts 222-227 and a cable group arrangement with varied
horizontal spacings. Support masts 222-227 are embedded at their
bases in concrete blocks for strength and stability. For example,
mast 222 is embedded at its base into block 232, which extends some
distance below ground level as illustrated.
[0021] System 200 also employs a number of partially buried
concrete anchors, of which FIG. 2 illustrates only structures 252
and 253 for clarity. Each one of the anchors is disposed between an
adjacent pair of the support masts. There may be several bases
between each or any mast pair. Advantageously, each anchor also
connects to some of the cables of the cable group for its
corresponding mast pair, adding to the cable array without the need
for additional support masts.
[0022] In system 200 and any other case where horizontal spacing
varies significantly, the spacing is considered to be the maximum
spacing of cables within an effective area of the cable group. For
example, the horizontal spacing of cables in system 200 is
indicated in FIG. 2 by the dimension mark "S." This horizontal
spacing is found along a horizontal axis between cables
intersecting at the top of mast 222 and vertical midpoint cable
242, which is tensioned by a midpoint anchor 252.
[0023] A support mast according to various aspects of the invention
includes any generally tall, slender structure suitable for (1)
sustaining the significant weight of the heavy structural cables it
must support and (2) at least partially sustaining the significant
sideways impulse of an impacting aircraft. A support mast need not
remain intact and vertical during an aircraft attack, because the
breaking resistance and inertia of the mass is likely sufficient to
counteract the impact force enough to disrupt the aircraft's
flight. If desired, however, a mast can be designed to remain
intact after such an attack, for example by ensuring that its
strength exceeds that of the cables between it and an adjacent
mast. Structure integral to the mast (e.g., composite materials,
wide-diameter steel) can provide such strength, as can opposing guy
wires, truss members, etc.
[0024] In accordance with various aspects of the invention, cables
are generally flexible, extremely slender, tension-bearing
structures that can sufficiently withstand impact from a wing or
other member of an oncoming aircraft to disrupt flight of that
aircraft. Such structures are typically made up of hundreds or even
thousands of twisted wire strands, but can also consist of or
include other structural material. While a cable need not remain
intact during an aircraft attack, the more resistance it can
provide to impact, the more damage it can do to the aircraft and
thus more significantly disrupt its flight. Cables can be of any
suitable type. For example, the design, fabrication, and
implementation of cables can be in accordance with any suitable
combination of the disclosures found in U.S. Pat. No. 4,473,915 to
Finsterwalder; U.S. Pat. No. 4,557,007 to Daiguji; U.S. Pat. No.
4,216,636 to Cordel; and U.S. Pat. No. 3,967,421 to Dufossez. The
detailed description portions of the aformentioned patents are
incorporated herein by reference, including any documents and
drawing figures referenced therein.
[0025] A cable group of a system according to various aspects of
invention includes a multitude of cables. (As used herein, the term
"multitude" simply means "three or more.") For example, the cable
group of mast pair 122-124 in system 100 (FIG. 1) includes a
multitude of vertically suspended cables (seven) and some
horizontal cables in a rectangular-hole configuration. In system
200 of FIG. 2, the cable groups of mast pairs 222-223 and 223-224
both include a larger multitude of cables (twelve) in an
irregular-polygon configuration.
[0026] In operation, system 100 of FIG. 1 passively protects
facility 110 against aerial attacks. In an illustrative example of
an aircraft flight-disrupting method of the invention, attacking
aircraft 150 (also illustrated in FIG. 1) is disrupted in its
suicidal flight toward facility 110 by vertically suspended cable
142. At the point depicted in FIG. 1, a wing 152 of aircraft 150
strikes cable 142. The resulting impact then tears wing 152 from
the fuselage of aircraft 150 and ignites fuel inside wing 152. The
fuselage of aircraft 150 rolls and drops violently due to lack of
lift from wing 152, and veers off its intended course toward
facility 110, striking the facility with a glancing blow rather
than a direct one. Meanwhile, wing 152 disappears into a fireball
that never reaches the interior of facility 110, burning up in
mid-air and outside the non-flammable exterior wall of facility
110.
[0027] The result of this exemplary flight disruption is
significantly reduced damage to facility 110. Fuel from wing 152
never reaches the interior of facility 110. Structure and remaining
fuel of aircraft 150, which may or may not ignite before impact,
penetrates less into facility 110 (if at all) because the glancing
blow imparts a far less concentrated impact on facility 110 than a
direct one.
[0028] According to particular aspects of the invention, the
following additional structures and configurations illustrated in
FIGS. 1 and 2 can be advantageously included.
[0029] EMP NETTING--In addition to structural cables, system 200
includes conductive netting between adjacent masts and as a "roof"
over facility 210. (For clarity, FIG. 2 only illustrates netting
between masts 226-227 and a fragment of "roof" netting.) The
netting comprised of a multitude of electrically conductive wires.
The wires are mechanically connected to the support masts (e.g.,
masts 226-227 in exemplary system 200) or, in a variation,
structural cables of the system's cable groups, or both. The wires
are sufficiently distributed around facility 210 and spaced close
enough to each other to form an electromagnetic shield around
facility given a cutoff frequency of interest. For example, if
shielding of spectral content up to 100 MHz is desired, the maximum
separation between conductive wires should be significantly less
than about 75 cm, which is a quarter wavelength in free space at
that frequency.
[0030] RAISING AND LOWERING SYSTEM--an advantage of employing
suspended cables as a barrier is the ability to raise and lower the
cable groups as desired, such as for maintenance or cable
replacement. In a variation of system 100, for example, masts
122-128 support top supporting cables 130-136 via end structures
(not shown) that can move up and down the masts. Any suitable type
of end structure can be employed, for example an anchor movably
mounted on a vertical track. Conventional pulley and winch systems
can assist in raising and lowering cables, as a group or one at a
time. Other alternatives include providing underground vertical
housing tubes for the masts and raising and lowering the masts
themselves from and into the tubes. A raise-lower variation of
system 100 preferably also includes a container (not shown) between
each mast pair, which can house cables of that mast pair's cable
group in a lowered configuration. Such a container can be, for
example, a lined trench in the ground between adjacent masts or a
trough-like structure at ground level that can double as a
perimeter wall.
[0031] GROUND-LEVEL CABLES--System 100 further includes
ground-level cables to help disrupt travel of ground-based
vehicles. (The groups of ground-level cables illustrated in FIG. 1
are referenced with numerals 170 and 172.) Advantageously, and
unlike a fixed fence or wall, cables 170, 172 can be raised and
lowered along with the other cables of system 100 in the variation
discussed above. A gap, shown between 170 and 172, can allow
traffic to pass, such as through a guardpoint, for access.
[0032] Public Notice Regarding the Scope the of the Invention and
Claims
[0033] The inventor considers various elements of the aspects and
methods recited in the claims filed with the application as
advantageous, perhaps even critical to certain implementations of
the invention. However, the inventors regard no particular element
as being "essential," except as set forth expressly in any
particular claim.
[0034] While the invention has been described in terms of preferred
embodiments and generally associated methods, the inventors
contemplate that alterations and permutations of the preferred
embodiments and methods will become apparent to those skilled in
the art upon a reading of the specification and a study of the
drawings. For example, a system can employ just three supporting
masts in a triangular arrangement. As another example, many more
than the six supporting masts employed in system 200 of FIG. 2 can
be employed.
[0035] Additional structure can be included, or additional
processes performed, while still practicing various aspects of the
invention claimed without reference to such structure or processes.
For example, contact explosives can be placed at lengths along the
suspended cables to promote explosion of an attacking aircraft and
reduce the chances of the aircraft impacting the protected
structure or, if it should, further reduce the resulting fire
intensity inside the structure.
[0036] Accordingly, neither the above description of preferred
exemplary embodiments nor the abstract defines or constrains the
invention. Rather, the issued claims variously define the
invention. Each variation of the invention is limited only by the
recited limitations of its respective claim, and equivalents
thereof, without limitation by other terms not present in the
claim.
[0037] In addition, aspects of the invention are particularly
pointed out in the claims using terminology that the inventors
regard as having its broadest reasonable interpretation; the more
specific interpretations of 35 U.S.C. .sctn. 112(6) are only
intended in those instances where the terms "means" or "steps" are
actually recited. As one example, the phrase "typical wingspan"
indicates a wingspan having a length representative of wingspans
typically encountered, not some precise average or median
statistic.
[0038] The words "comprising," "including," and "having" are
intended as open-ended terminology, with the same meaning as if the
phrase "at least" were appended after each instance thereof. A
clause using the term "whereby" merely states the result of the
limitations in any claim in which it may appear and does not set
forth an additional limitation therein. Both in the claims and in
the description above, the conjunction "or" between alternative
elements means "and/or," and thus does not imply that the elements
are mutually exclusive unless context or a specific statement
indicates otherwise.
* * * * *