Note: Descriptions are shown in the official language in which they were submitted.
CA 02605882 2007-09-28
BALLISTIC RESISTANT FLIGHT DECK DOOR AND
METHOD OF MAKING SAME
FIELD OF THE INVENTION
The present invention relates to flight deck doors for aircraft, and
particularly relates to ballistic and intruder proof flight deck doors for
aircraft.
BACKGROUND OF THE INVENTION
Most aircraft have a fuselage which defines a passenger section, a
cargo section, and a pilot or flight deck section. Most of the passenger
section
and the flight deck are pressurized portions of the aircraft adapted to
carrying
people. The flight deck is generally separated from the passenger area by a
door, sometimes referred to as the "cockpit door", which limits entry to the
flight deck but is not meant to be impenetrable by a firearm or person, even
when closed.
Most often the flight deck door simply provides a temporary
impediment between the passenger section and the flight deck or pilot
section. Most often it functions to simply isolate the pilots from the
passengers
so that they are not disturbed by the passengers during a flight. The flight
deck door may also provide acoustic dampening for the flight deck, both to
assist in quieting the flight deck and to shield the flight deck from the
noise
generated in the passenger area. In particular, the flight deck is generally
situated at the front of an aircraft and therefore it is buffeted most by the
oncoming wind of the atmosphere as the aircraft proceeds in flight. This wind
noise can be particularly loud in the flight deck, but is dampened by an
appropriately constructed flight deck door.
Recent events, however, have also made it desirable to provide a
greater degree of fortitude to the flight deck door. In particular, it has
become
desirable to make the flight deck door substantially impervious to ballistic
and
intruder attacks. It is desirable to add these features so that if an attacker
is
amongst the passengers, in the passenger area, the flight deck door will
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CA 02605882 2007-09-28
provide a substantial, if not impervious, blockade to any attack by a person
on
the pilot and co-pilot. In this way the pilot can continue to control the
aircraft
regardless of the action of an attacker in the passenger section and guide the
plane to safety. Furthermore, this can reduce or substantially eliminate the
possibility that a person in the passenger section gains unauthorized access
to the flight deck to gain control of the aircraft.
SUMMARY OF THE INVENTION
The above and other features and advantages are provided by a flight
deck door in accordance with a preferred embodiment of the present
invention. A flight deck door for an aircraft that is both ballistic resistant
and
intruder proof is disclosed. The flight deck door may also provide acoustic
dampening properties for the flight deck. The flight deck door includes a
laminated ballistic resistant material which can also provide intruder
resistant
properties. The ballistic resistant or armor material can be laminated onto a
core to provide additional rigidity to the flight deck door.
In accordance with one aspect of the invention, there is provided a
method for forming an armor layer for a door. The method involves providing
a first layer of an armor material including a fiber structure with a resin
surrounding the fibers, and providing a second layer of an armor material
comprising a fiber structure with a resin surrounding the fibers. The method
also involves placing the first layer adjacent the second layer, applying a
pressure of at least 5 pounds per square inch between the first layer and the
second layer, and heating the first layer and the second layer to at least 120
C such that applying the pressure and heating occurs generally
simultaneously and continues for at least about 30 minutes.
The method may also involve providing at least ten layers of the armor
material, placing each of the layers substantially adjacent to one another to
form a pre-laminate portion, and curing the pre-laminate to form an armor
layer laminate having a substantially affixed laminated substructure of the
discrete armor layers.
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CA 02605882 2007-09-28
Curing the pre-laminate may involve applying at least five pounds of
pressure per square inch to the pre-laminate portion, heating the pre-laminate
portion to at least 1200 C, and holding the pre-laminate at the pressure and
the temperature for at least 30 minutes.
The first layer of armor and the second layer of armor may include
layers of Kevlar material.
The applied pressure may be less than 40 pounds per square inch.
The method may further involve providing a rigid layer having an open-
cell structure, providing an adhesive layer, and operably affixing the armor
layer laminate to the rigid layer with the adhesive layer such that the door
is
able to stop effective penetration of a projectile fired from a firearm.
The rigid layer may provide a sound dampening ability to the door to
substantially reduce noise on a side of the door.
Further areas of applicability of the present invention will become
apparent from the detailed description provided hereinafter. It should be
understood that the detailed description and specific examples, while
indicating the preferred embodiments of the invention, are intended for
purposes of illustration only and are not intended to limit the scope of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the
detailed description and the accompanying drawings, wherein:
Figure 1 is a detail perspective view of an aircraft with a flight deck
door according to the present invention;
Figure 2 is a cross-sectional view of ballistic and intruder resistant flight
deck door including acoustic dampening effects along line A-A of Figure 1
according to a first embodiment of the present invention; and
Figure 3 is a cross-sectional view of a ballistic resistant and intruder
proof flight deck door along line A-A of Figure 1 according to a second
embodiment of the present invention.
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CA 02605882 2007-09-28
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following description of the preferred embodiment(s) is merely
exemplary in nature and is in no way intended to limit the invention, its
application or uses.
With reference to figure 1 an aircraft 4 includes an exterior skin 5
defining a fuselage. The inside of the aircraft 4 includes a flight deck wall
6
including a flight deck door 10. The flight deck wall 6 and flight deck door
10
separate the flight deck area or side 12 from the passenger area or side 14.
The flight deck door 10 allows restricted access to the flight deck side 12
from
the passenger side 14. The flight deck door 10 may also be used as a door at
other locations within the fuselage if desired. Generally, the flight deck
door
10 is formed to fit into a door jam in the flight deck wall 6. One side the
flight
deck door 10 includes a hinge 7 which mates with a hinge 8 of the door jam.
This allows the flight deck door 10 to be easily opened and closed. Also, the
flight deck door 10 includes a door latch or locking mechanism 9. The locking
mechanism 9 mates with a jam locking mechanism (not particularly shown) on
the door jam to lock the flight deck door 10 in a closed position. The
particulars of these portions are not relevant to the present invention, but
are
understood to be a part of any functioning flight deck door 10.
With reference to Figure 2, a cross section of the an intrusion and
bullet proof and acoustic dampening flight deck door along line A-A is
illustrated according to a first preferred embodiment of the present
invention.
Though it is understood that the physical dimensions of the section is not
proportional to more clearly illustrate the flight deck door 10. The flight
deck
door 10 is installed in the aircraft 4 such that a first or flight deck side
12 faces
the flight deck and a second or passenger side 14 faces a passenger
compartment.
The flight deck door 10 is a laminated door comprising a plurality of
individual layers. Each layer is affixed to an adjacent layer with an
appropriate
method. Generally, either cold curing or heated curing is used along with
appropriate adhesives. Cold curing is used to define an adhesive or process
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CA 02605882 2007-09-28
that cures at generally room temperature or about 21 C(70 F). Heated
curing is any method which requires heating to a temperature greater than
room temperature. Each layer provides a certain amount of rigidity to the
flight
deck door 10. The entire flight deck door 10, however, is preferably
approximately 25.4 mm (1.0 inch) thick. It will be understood that the flight
deck door 10 may also include a door which is thicker than 1.0 inch, but
excessively thick doors are generally undesirable because of the added
weight they impose.
The flight deck door 10 includes a first layer 16 that comprises a
perforated decorative laminate. The first layer 16 simply provides a
decorative
covering to the flight deck door 10. It would be understood that the
decorative
laminate may be any appropriate decorative material. It will be understood,
however, that if decoration or aesthetics are not a primary concern, then the
first layer 16 is not needed. Perforations 16a in the first layer 16 also
provide
the initial acoustic dampening feature. Therefore, if a first layer 16 is
desired,
it is preferably perforated. The first layer 16, however, also provides a
degree
of rigidity to the flight deck door 10.
A second layer 18 is an acoustic fabric. Part of the function of the flight
deck door 10 is to dampen acoustic noise from the flight deck side 12. The
second layer 18 provides a first means of acoustic dampening by providing a
first muffling layer for the flight deck door 10. The perforations in the
first layer
16 allow sound waves to pass therethrough and become initially muffled in the
second layer 18, while also continuing through the second layer 18.
The first layer 16 and second layer 18 form a first laminate section 20.
The first laminate section 20 is held together by a suitable adhesive layer
21,
and preferably a room temperature adhesive, such as that generally known in
the art, to provide a permanent attachment of the first layer 16 to the second
layer 18. Preferably the adhesive layer 21 is a two part polyester cold curing
adhesive. It will be understood, however, that if a decorative laminate first
layer 16 is not desired, then the first section 20 will include only the
second
layer 18.
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A third layer 22 includes a fiberglass epoxy prepreg. The fiberglass
epoxy prepreg preferably comprises a "fly screen fabric". The third layer 22
generally includes fiberglass strands interweaved to form an open square
lattice structure, similar to that of a house window screen. The open holes in
the third layer 22 generally have a side length between about 0.10 inch and
about 0.50 inch (about 0.25 cm and about 1.30 cm). Furthermore, the
fiberglass strands of the third layer 22 are pre-impregnated with an epoxy.
The third layer 22 provides some rigidity and strength to the flight deck door
and does not require a separate adhesive to affix it to a fourth layer 24. In
10 particular, the epoxy not only provides rigidity to the third layer 22, but
also
functions as an adhesive layer 25 between the third layer 22 and the fourth
layer 24 to secure these layers. It will be understood, however, that the
adhesive layer 25 may include a separate appropriate adhesive if required.
The fourth layer 24 is a honeycomb acoustic core. In particular, the
fourth layer 24 includes a plurality of open cells 24a. Each open cell 24a is
formed along a central axis 24b and the central axis 24b is arranged
perpendicular to the plane formed by the flight deck door 10. Each cell of the
fourth layer 24 has a length of between about 0.50 inches and about 1.0
inches (about 1.25 cm and about 2.50 cm) and cross-sectional diameter of
between about 0.05 inches and about 0.50 inches (about 1.00 cm and about
1.50 cm). The fourth layer 24 provides the main acoustic dampening feature
of the flight deck door 10. Sound waves enter the open cell structure of the
fourth layer 24 and lose most of their energy in the open cell structure.
A fifth layer 26 includes a second fiberglass epoxy prepreg layer. The
fifth layer 26 is substantially similar to the third layer 22 described above.
It
will also be understood that the fifth layer 26 can form the adhesive layer
27,
between the fourth layer 24 and the fifth layer 26, a distinct adhesive layer
27
may also be provided. The third layer 22, fourth layer 24, and fifth layer 26
form a second section 28 which is cured in a multi-opening press. The multi-
opening press (not illustrated) is commonly known in the art. Generally, the
multi-opening press receives a plurality of layers which can be laminated and
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CA 02605882 2007-09-28
cured under the same physical conditions. Therefore, a plurality of second
sections 28 can be formed at one time in a multi-opening press.
A sixth layer is an armor layer 30. The armor layer 30 may include any
appropriate armor material. Preferably the armor layer 30 includes a plurality
of Kevlar armor layers. Kevlar armor is known to provide substantial
ballistic
resistance to firearm projectiles. The armor layer 30 generally includes
preferably between about 15 and about 25 Kevlar armor layers. The armor
layer 30 is generally between about 0.10 inch and about 0.60 inch thick (about
0.25 cm and about 1.52 cm). More preferably, layers of Kevlar, impregnated
with a PVB phenolic resin at about 15% fluidizable resin, are employed to
provide the desired ballistic resistance. These individual Keviar armor layers
are laminated to form the armor layer 30, described further herein. The armor
layer 30 is affixed to the second section with an adhesive layer 31. The
adhesive layer may be any appropriate adhesive that is known in the art, such
as a two part epoxy cold curing adhesive.
A seventh layer 32 is a second decorative laminate. The seventh layer
32 need not be perforated as is the first layer 16. The seventh layer 32 does
not need to provide an acoustic dampening function for the passenger
compartment. The seventh layer 32 is employed simply to blend the flight
deck door 10 into the surroundings of the passenger compartment.
Additionally, an adhesive layer 34 of any appropriate and known adhesive is
used to affix the seventh layer 32 to the exterior of the armor layer 30.
The flight deck door 10 according to the first embodiment includes
acoustic dampening properties. In particular, the flight deck door 10 is
particularly well suited for use in a Boeing 747-400 aircraft. It is
understood,
however, that the acoustic dampening properties of the flight deck door 10
may be used in any appropriate aircraft and are not limited to a Boeing 747-
400 aircraft.
With reference to Figure 1 and 3, a second embodiment of an intrusion
resistant and bullet proof flight deck door 100 is illustrated. The flight
deck
door 100 is installed in the flight deck wall 6 of an aircraft 4 including
hinges 7
and 8 and a door latch 9 the flight deck side 12 and the passenger side 14.
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The flight deck door 100 is a laminated door comprising a plurality of
individual layers. Each layer is affixed to an adjacent layer with an
appropriate
method. Generally, either cold curing or heated curing, as described herein,
is
used along with the appropriate adhesives. Each layer provides a certain
amount of rigidity to the flight deck door 100. The entire flight deck door
100,
however, is approximately 25.4 mm (1.0 inch) thick. It will be understood that
the flight deck door 100 may also include a door which is thicker than 1.0
inch,
but limiting the weight of the door is also an important counter veiling
consideration in any door design desirable to be as small as possible thereby
reducing weight on the aircraft.
A first decorative laminate layer 106 on the flight deck side 12 provides
an aesthetic covering for the flight deck door 100. It will be understood that
the decorative laminate layer 106 may be an appropriate decorative laminate.
Additionally, an adhesive layer 109 of any appropriate and known adhesive is
used to affix the first layer 106 to the exterior of the armor layer 108. It
will
also be understood that the first decorative laminate layer 106 is not
absolutely necessary for the flight deck door 100. In particular, if
aesthetics
are not a primary concern, the first decorative laminate layer 106 can be
omitted.
Next, an armor layer 108 provides ballistic and intruder resistance to
the flight deck door 100. The armor layer 108 includes preferably between
about 10 and about 15 armor laminate layers. Preferably, Kevlar laminate
layers are used, though it will be understood any appropriate number of any
appropriate armor laminate may be used. More preferably about 12 layers of
Kevlar laminate layers are laminated together to form the armor layer 108.
The armor layer 108 is preferably between about 0.25 cm and about 0.76 cm
(about 0.10 inch and about 0.30 inch) thick. The armor layer 108 is formed in
a process similar to the process of forming the armor layer 30.
A third or first minor armor layer 110 may also include Kevlar armor
layers. The third layer 110 provides additional rigidity, as well as a degree
of
ballistic and intrusion resistance to the flight deck door 100. It is
understood,
however, that the armor layer 108 provides substantially all of the ballistic
and
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CA 02605882 2007-09-28
intruder resistance of the flight deck door 100. The third layer 110 comprises
between about 2 and about 5 laminate armor layers. Preferably, Kevlar 745
armor is used. Again, the formation of the third layer 110 is substantially
identical to the formation of the armor layer 108.
The fourth layer 112 is a fiberglass phenolic prepreg. The fiberglass
phenolic prepreg comprises a "woven fabric". The fourth layer 112, however,
includes about 40% fluidizable resin. Therefore, there is a greater resin
volume between the third layer 110 and the core or fifth layer 114. This
provides a substantial amount of resin which allows the armor layer 108 to
bond to the core layer 114.
The core layer 114 is preferably between about 0.40 and about 0.80
inches thick. The core layer 114 may be similar or identical to the honeycomb
layer 24 of door 10 or may be formed by any other appropriate core layer of
material. Preferably, the core layer 114 of the flight deck door 100 is a
material other than the core layer 24 according to the first embodiment. In
particular, the core layer 114 is a honeycomb layer which includes an open
cell 114a and is approximately 8 pounds per cubic foot. It will be understood,
however, that if other layers provide sufficient rigidity, then the core layer
114
may be omitted.
A sixth layer 116 is a second layer of the fiberglass phenolic prepreg.
While a seventh or second minor armor layer 118 is another layer of armor
laminate. The seventh layer 118 is substantially similar to the third layer
110
described above. The third layer 110 through the seventh layer 118 are
formed together in a multi-opening press to form a main section 120.
Furthermore, each Kevlar armor layer of the minor armor layers 110 and 118
may be placed in the multi-opening press separately and cured with the main
section 120. This removes additional steps of individually laminating and
curing the minor armor layers 110 and 118.
The main section 120 provides the backbone to which the armor layer
108 is affixed with an adhesive layer 121. It will be understood that the
adhesive layer 121 is any appropriate and known adhesive such as a two part
epoxy cold curing adhesive. Furthermore, the main section 120 is affixed
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together with the fluidizable resin from the fiberglass phenolic prepreg of
the
fourth layer 112 and the sixth layer 116. It will be understood, however, that
a
separate adhesive may be used if desired.
Finally, an eighth layer 122 includes a decorative laminate. The eighth
layer 122 may be any appropriate decorative laminate. Again, it will be
understood that if aesthetics are not a primary concern of the flight deck
door
100 the decorative laminate 122 may be eliminated. Also, an adhesive layer
124 of any appropriate and known adhesive is used to affix the eighth layer
122 to the main section 120.
The flight deck door 100, according to the second preferred
embodiment to the present invention, does not include any acoustic
dampening material that the door 10 includes. Thus, the flight deck door 100,
does not include any acoustic dampening layer on the flight deck side 12.
Neither the first layer 106 or the armor layer 108 are acoustically dampening.
The armor layer 108 provides the ballistic intrusion resistance of the flight
deck door 100.
The armor layers 30 and 108, and minor armor layers 110 and 118, of
the main section 120, are formed preferably of Kevlar armor layers. The armor
layers 30, 108 and the main section 120 are also formed in a multi-opening
press. Additionally, the armor layers 30, 108 and the main section 120 are
formed under the same physical circumstances and conditions so that these
layers may be formed at one time in a multi-opening press. Alternately,
numerous layers of a particular armor layer, such as the armor layer 30, or
main section 120 can be formed at one time.
While the armor layer 30 will be referenced in the following description
of forming the armor layer, it will be understood that the other armor layers
108, and main section 120 are formed in a substantially similar manner. The
armor layer 30 includes preferably 20 Kevlar armor layers. These 20 Keviar
armor layers are placed into a multi-opening press one on top of another.
They are then subjected to temperatures of between about 120 C and about
146 C(250 F and about 295 F) and between about 5 and about 30 pounds
per square inch (psi) of pressure. The plurality of individual layers of
Kevlar
CA 02605882 2007-09-28
armor are subjected to these conditions for as little as about 30 minutes, and
generally between about 60 minutes and about 120 minutes. This process
forms the armor layer 30 when the plurality of individual Kevlar armor layers
have been cured and are then affixed together as a single layer or
substructure. Nevertheless, the armor layer 30 is formed as a discrete
laminate layer. After curing, the armor layer 30 is then cut to the desired
dimensions needed to form the flight deck door 10, and is affixed to section
28
with a cold curing adhesive. Cold curing adhesive is defined to include any
adhesive which is not required to be heated to cure properly. It will be
understood, however, that a heat cured adhesive may also be used.
The process described above does not substantially reduce or hinder
the effectiveness of the individual Kevlar armor layers. For example, the
lattice structure of the Kevlar fibers is only minimally compressed or
substantially uncompressed because low pressures are used in the process
described above. Therefore, they are able to move and deflect the energy of a
projectile as it enters the armor layer 30. Kevlar armor layers provide
ballistic
resistance by deflecting and absorbing the energy of a projectile. If the
fibers
of the Kevlar armor layers are compressed there is less space for them to
move, thereby reducing the ballistic effectiveness of any one Kevlar armor
sub-layer.
Additionally, the low processing temperatures allow the resin to be less
brittle in the individual Kevlar armor layers. The greater the processing
temperature of the Kevlar armor layers, the lower the ballistic effectiveness
becomes of the armor layer 30.
The armor layer 108 of the flight deck door 100 preferably includes only
twelve layers of Kevlar armor material. The construction and processing
techniques described above reduce the number of layers required to provide
the equivalent ballistic resistance of a greater number of layers. The armor
layer 30 of the flight deck door 10 includes approximately twenty Kevlar armor
layers due to the fact that section 28 reduces the deflection of the armor
layer
30. In particular, as described above, the armor layer 30 works best when it
is
able to deflect a distance to reduce the energy of the projectile. If that
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CA 02605882 2007-09-28
deflection is reduced, due to exterior or other constraints, such as section
28,
then the armor layer 30 must be increased in thickness.
The flight deck doors 10 and 100 provide a significant degree of
ballistic resistance. That is, the flight deck doors 10 and 100 completely
stop
many ballistic projectiles fired from a weapon. Effective penetration is when
a
projectile that is able to penetrate and cause damage after exiting a
material.
Therefore, even though a projectile passes completely through a material, it
can be said that it has not effectively penetrated the material if it can not
cause harm after escaping the material. In particular, a .44 magnum SJHP
projectile, generally having a mass between about 11 g and about 20 g,
reaching the door at velocities between about 426 m and about 487 m per
second (between about 1400 and about 1600 feet per second (FPS)) cannot
effectively penetrate the flight deck door 10 and 100. Therefore, the flight
deck
doors 10 and 100 substantially eliminate the possibility of a projectile being
fired from the passenger side 14 and effectively penetrating the flight deck
door 10, 100 to the flight deck side 12.
It will be understood that various other alternatives may also use an
armor layer as described in the present application. An alternative
embodiment may be similar to the first embodiment, illustrated in Figure 2,
except that the first lamination layer 20 is replaced with a non-perforated
decorative laminate similar to layer 106, illustrated in Figure 3. In
addition,
layer 22 may be replaced with a woven glass phenolic prepreg similar to layer
26. Lastly, layer 30 may include any required number of Keviar layers to
provide the ballistic resistance required for the flight deck door 10. Also,
armor
layer 30 may be positioned between the first section 20 and the second
section 28. This alternative embodiment provides excellent ballistic
resistance, especially on "gaps". Gaps may be formed due to structural
requirements such as fasteners to install the door in the aircraft. Such gaps
in
the structure of the door can provide weak areas which may be more
susceptible to intrusion. Nevertheless including a larger armor layer on the
passenger compartment side of the door may decrease the effect that such
fasteners and gaps have on the resistance of the armor layer.
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The description of the invention is merely exemplary in nature and,
thus, variations that do not depart from the gist of the invention are
intended
to be within the scope of the invention. Such variations are not to be
regarded
as a departure from the spirit and scope of the invention.
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