Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEM FOR AIRBORNE TRANSPORT OF FLAMMABLE LIQUIDS
Field
[0001] The present invention relates generally to a system for transporting
flammable
liquids, in particular to an aircraft incorporating the system and being
usable to transport
flammable liquids to remote sites.
Background
[0002] Consumers of flammable liquids, such as gasoline, kerosene and heating
oil
are often located at remote sites that are inconvenient for common ground-
based transport of the
liquids. For example, industrial sites such as mining and lumber operations
are often in remote
locations that are not served by improved roads. Similarly, remote villages in
many wilderness
or arctic areas are not accessible by land or water routes during certain
seasons. Finally,
wilderness camps and lodges are often situated far from any land or water
routes.
[0003] One way to transport supplies to the aforementioned remote sites is to
utilize
small and medium-sized aircraft. Aircraft can be equipped with tundra tires
and rugged landing
gear for landing and takeoff from unimproved landing strips and beaches.
Likewise, aircraft can
be equipped with floats for operation upon lakes and rivers, or skis for
operation upon snow-
covered surfaces. However, special consideration must be given to air
transport of flammable
liquids, as improper containers are subject to damage or leakage with an
attendant risk of
explosion or fire. Another drawback of many fuel containers is that they are
not conveniently
sized or shaped to efficiently fit the geometries of aircraft cargo bays.
Furthermore, loading and
unloading containers of flammable liquids is laborious and potentially
hazardous. Improper
stowing of the containers in an aircraft cargo bay can also result in a weight-
and-balance
configuration that is outside the safe operating envelope of the aircraft.
Lastly, containers of
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flammable liquids can become hazardous if they are improperly secured in the
aircraft and are
dislodged during aircraft operation. There is a need for a way to safely
transport flammable
liquids in aircraft.
Summary
[0004] A system for airborne transportation of flammable liquids is disclosed
according to an embodiment of the present invention. Storage containers are
joined to the
aircraft at locations that are appropriate to the aircraft's center of
gravity, so as to maintain an
appropriate weight and balance for the aircraft throughout its range of
operating limitations with
or without flammable liquids in the containers. Filler openings in the storage
containers are each
selectably closable by a cap, the filler openings allowing for rapid and
efficient filling of the
storage containers with flammable liquids. A vent system deters build-up of
flammable vapours
in the storage containers. In addition, a fuel jettison system allows for
rapid removal of
flammable liquids from the storage containers in the event of an emergency.
The fuel jettison
system may include a biased lid to ensure reliable operation of the jettison
system under low-
temperature and icing environmental conditions.
[0005] An aspect of the present invention is a system for transport of
flammable
liquids using an aircraft. A fuel tank and a reservoir, each for storing
flammable liquids, are
joined to the aircraft. A fuel jettison subsystem is coupled between an
interior portion and an
exterior portion of the reservoir to selectably expel fuel from the reservoir
to an exterior portion
of the aircraft. The fuel jettison subsystem includes a jettison valve opening
formed in the
reservoir. A lid selectably closes off the opening. A biasing member urges the
lid away from the
jettison valve opening. A solenoid retains the lid in the jettison valve
opening when unactuated
and releases the lid when actuated. A jettison linkage is coupled to the
solenoid, the jettison
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linkage being operable to selectably actuate the solenoid. The lid is urged
away from the jettison
valve opening by the biasing member when the t solenoid is actuated by the
jettison linkage.
[00061 Another aspect of the present invention is a system for transport of
flammable
liquids using an aircraft. The system comprises a fuel tank for storing
flammable liquids, the fuel
tank being joined to the aircraft. The fuel tank has a first selectably
closable fill port and further
includes a first selectably closable discharge port. A reservoir for storing
flammable liquids
independent of the fuel tank is also joined to the aircraft. The reservoir has
a second selectably
closable fill port and further includes a second selectably closable discharge
port.
[00071 A fuel jettison subsystem is coupled between an interior portion and an
exterior portion of the reservoir to selectably expel fuel from the reservoir
to an exterior portion
of the aircraft in the event of an exigent circumstance wherein landing the
aircraft with fuel in the
fuel tank and the reservoir inordinately increases the risk of landing. The
subsystem includes a
first jettison valve opening formed in the reservoir. A first lid selectably
closes off the first
jettison valve opening. A first biasing member urges the first lid away from
the first jettison
valve opening. A first solenoid retains the first lid in the first jettison
valve opening when
unactuated and releases the first lid when actuated. A jettison linkage is
coupled to the first
solenoid, the jettison linkage being operable to selectably actuate the first
solenoid. The first lid
is urged away from the first jettison valve opening by the first biasing
member when the first
solenoid is actuated by the jettison linkage.
[00081 The system also includes a first suction valve coupled between an
interior
portion and an exterior portion of the fuel tank to selectably admit air to
the fuel tank, the first
suction valve being closed below a predetermined negative pressure threshold
in the fuel tank
and being open when the pressure in the fuel tank exceeds the negative
threshold. A second
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suction valve is coupled between the interior portion and the exterior portion
of the reservoir to
selectably admit air to the reservoir, the second suction valve being closed
below a
predetermined negative pressure threshold in the reservoir and being open when
the pressure in
the reservoir exceeds the negative threshold.
[0009] The system further includes a first pressure relief valve coupled
between the
interior portion and the exterior portion of the fuel tank to selectably expel
at least one of air and
fuel vapours from the fuel tank, the first pressure relief valve being closed
below a predetermined
positive pressure threshold in the fuel tank and being open when the pressure
in the fuel tank
exceeds the positive threshold. A second pressure relief valve is coupled
between the interior
portion and the exterior portion of the reservoir to selectably expel at least
one of air and fuel
vapours from the reservoir, the second pressure relief valve being closed
below a predetermined
positive pressure threshold in the reservoir and being open when the pressure
in the reservoir
exceeds the positive threshold.
Brief Description of the Drawings
[0010] Further features of the inventive embodiments will become apparent to
those
skilled in the art to which the embodiments relate from reading the
specification and claims with
reference to the accompanying drawings, in which:
[0011] Fig. 1 shows the general arrangement of a system for airborne
transportation
of flammable fluids according to an embodiment of the present invention;
[0012] Fig. 2 is a top plan view of a hopper fuel tank of the system of Fig.
1;
[0013] Fig. 3 shows a venting subsystem of the system of Fig. 1;
[0014] Fig. 4 shows further details of the hopper fuel tank of Fig. 2;
[0015] Fig. 5 is a side elevational view of a reservoir of the system of Fig.
1;
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[0016] Fig. 6 is a top plan view of the reservoir of Fig. 5;
[0017] Fig. 7 is a schematic diagram showing the venting subsystem of Fig. 3,
a fuel
cargo jettison subsystem and a fuel cargo offload subsystem according to an
embodiment of the
present invention;
[0018] Fig. 8 is a bottom plan view of a fuel cargo jettison valve according
to an
embodiment of the present invention;
[0019] Fig. 9A is a side elevational view showing details of the jettison
valve of Fig.
8;
[0020] Fig. 9B is a first end elevational view showing additional details of
the jettison
valve of Fig. 8;
[0021] Fig. 9C is a second end elevational view showing further details of the
jettison
valve of Fig. 8;
[0022] Fig. 10 is a schematic diagram showing further details of the fuel
jettison
subsystem of Fig. 7;
[0023] Fig. 11 is a side elevational view of a fuel offload subsystem of the
system of
Fig. 1; and
[0024] Fig. 12 shows a vapour barrier for the hopper fuel tank of Fig. 2
Detailed Description
[0025] The general arrangement of a system 10 for airborne transportation of
flammable liquids is shown in Fig. 1, the system being incorporated into an
aircraft 12. System
includes a hopper fuel tank 14, an auxiliary fuel tank 16, a fuel cargo
jettison subsystem 18, a
fuel cargo vent subsystem 20 and a fuel cargo offload subsystem 22.
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[00261 As shown in Fig. 1, hopper fuel tank 14 is located in a fuselage 24 of
aircraft
12, forward of a pilot compartment 26 and aft of an engine compartment 28.
With reference now
to Figs. 2 through 4, hopper fuel tank 14 may include at least one selectably
removable, sealable
access panel 30 to accommodate cleaning and inspection of the hopper fuel
tank. Hopper fuel
tank 14 further includes a fill port 32 having a cap 34 that is selectably
removable to fill the
hopper fuel tank with flammable liquids. A float-type vent valve 36 is coupled
to fuel cargo vent
subsystem 20 to allow venting of gases in hopper fuel tank 14 to the exterior
of aircraft 12 and to
provide an over flow path to the exterior of aircraft 12 for flammable liquids
in the tank 14. Vent
valve 36 closes when aircraft 12 is not level, is accelerating, or is
decelerating, to prevent fuel
from escaping under these conditions.
[00271 A pressure relief valve 38 in communication with hopper fuel tank 14 is
normally closed off but opens to the exterior of aircraft 12 in the event that
the pressure in the
hopper tank exceeds a predetermined pressure value, thereby preventing damage
to the tank due
to an overpressure condition. This can occur, for example, as a result of
pressure changes in
hopper fuel tank 14 due to changes in the operating altitude of aircraft 12 or
the thermal
coefficient of expansion of flammable liquids in the hopper fuel tank with
vent 36 in a blocked or
closed condition.
[00281 With reference to Figs. 3 and 4 together, in one embodiment of the
present
invention hopper fuel tank 14 may include a sidewall 40 that is spaced apart
from a bulkhead 42
of aircraft 12. Together sidewall 40 and bulkhead 42 form a secondary bulkhead
43 with an air
space between hopper fuel tank 14 and pilot compartment 26 (Fig. 1), the
secondary bulkhead
having a float-type vent valve 44 and a hollow drain tube 46 extending from
the secondary
bulkhead to the exterior of aircraft 12. Any leakage in secondary bulkhead 43,
which is
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indicative of a leak in hopper fuel tank 14, may detected by inspecting drain
46 at its exit point to
the exterior of aircraft 12 for the presence of fuel prior to flight. In the
event of an in-flight
leakage of hopper fuel tank 14, leaked fluids will be directed into the
airstream of aircraft 12 by
drain 46.
[0029] Hopper fuel tank 14 may be made from any materials that are compatible
with
flammable liquids and the expected environment for aircraft 12. Example
materials include,
without limitation, metal such as aluminum and epoxy resins such as Derakane ,
available from
Ashland Composite Polymers of Columbus, Ohio. Electrically conductive portions
of hopper
fuel tank 14 may be grounded to the airframe of aircraft 12 in any desired
manner, such as with
electrically conductive brackets, fasteners, wiring, braids, straps and cables
to deter the buildup
of static electricity and to route lightning discharge currents in a manner to
deter damage to the
hopper fuel tank or its contents.
[0030] Referring now to Figs. 1, 3 and 5, auxiliary fuel tank 16 includes an
aerodynamic fairing 48 covering a reservoir tank 50, both the fairing and
reservoir being
removably attached to a lower portion of fuselage 24 of aircraft 12. A top
portion 52 of reservoir
50, shown in Fig. 6, is spaced apart from fuselage 24 and preferably includes
one or more access
panels 30, a fill port 32, a cap 34 and a pressure relief valve 38. A vent 54
(Fig. 3) is coupled to
fuel cargo vent subsystem 20 and is detailed further below.
[0031] Reservoir 50 may be made from any materials that are compatible with
flammable liquids and the expected environment for aircraft 12. Example
materials include,
without limitation, metals such as aluminum. Reservoir 50 may further include
one or more
internal baffles and/or webbing 56 (Figs. 5, 6) to prevent sloshing of
flammable liquids stored
therein. Reservoir 50 is preferably attached to fuselage 24 with fasteners
that allow the reservoir
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to be readily removed in the event the reservoir requires servicing.
Electrically conductive
portions of hopper reservoir 50 may be grounded to the airframe of aircraft 12
in any desired
manner, such as with electrically conductive brackets, fasteners, wiring,
braids, straps and cables
to deter the buildup of static electricity and to route lightning discharge
currents in a manner to
deter damage to the reservoir or its contents.
[0032] Fairing 48 may be made from a single piece, or may comprise a plurality
of
fairings. Fairing 48 may be made from any materials that are suitable for the
expected
environment for aircraft 12. Example materials include, without limitation,
epoxy fiberglass and
metals such as aluminum. Fairing 48 may be painted, if desired, and may
further include an
opening or a selectable closure such as a hinged lid to provide access to fill
port 32 on top
portion 52 of reservoir 50. Fairing 48 is preferably attached to fuselage 24
with fasteners that
allow the fairing to be readily removed in the event reservoir 50 requires
servicing.
[0033] A schematic diagram of fuel cargo jettison subsystem 18 is shown in
Fig. 7.
Hopper fuel tank 14 includes a first jettison valve 58 and reservoir 50
includes a second jettison
valve 60, the jettison valves being coupled to a control 62 operable from
pilot compartment 26
(Fig. 1), such as a lever or handle, actuable by a mechanical, electrical or
pneumatic linkage 64.
Hopper fuel tank 14 and reservoir 50 each further include a suction valve 66.
In the event that
flammable liquids stored in tank 14 and reservoir 50 must be jettisoned, an
operator of aircraft 12
operates control 62, causing jettison valves 58, 60 to open. Suction valves 66
open at a resulting
low negative pressure in tank 14 and reservoir 50, allowing a high volume of
air to flow into the
tank and the reservoir as the flammable liquid is rapidly discharged.
[0034] Details of jettison valve 60 are shown in Figs. 8 and 9A-C. Jettison
valve 60
selectably closes off an opening 68 in reservoir 50 with a lid 70 having an O-
ring seal 72. Lid 70
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is coupled to a link 74 by a spacer 76. Link 74, in turn, is hingedly attached
to a support 78 at a
first end by a fastener 80. A second, opposing end of link 74 includes a
locking tab 82 with an
aperture 84. A biasing member 86 is attached to link 74 and extends away from
the link to
contact a housing 88 of jettison valve 60, the biasing member being in a
loaded condition when
lid 70 closes off opening 68. An output shaft 90 of a solenoid 92 engages
aperture 84 when the
solenoid is in an unactuated condition, the solenoid and the locking tab
cooperating to resist
biasing member 86 and keep lid 70 in a closed condition, closing off opening
68.
[0035] With reference to Figs. 8 through 10 together, when jettison valve 60
is to be
opened an operator operates control 62, which in turn actuates solenoid 92 via
linkage 64.
Output shaft 90 moves away from aperture 84 of locking tab 82, allowing
biasing member 86 to
urge link 74 to pivot about support 78, positively moving lid 70 away from
opening 68 and thus
exposing the opening, allowing fuel in reservoir 50 to be rapidly discharged.
Biasing member 86
aids to urge lid 70 away from opening 68, ensuring the operation of the
jettison valve under low-
temperature and icing environmental conditions. It should be noted that
control 62, linkage 64
and solenoid 92 may be realized using mechanical, electrical or pneumatic
components within
the scope of the invention.
[0036] Details of fuel cargo vent subsystem 20, shown in Fig. 3, comprises a
hopper
fuel tank vent 94, a secondary bulkhead vent 96 and a reservoir vent 98.
Hopper fuel tank vent
94 includes a vent fitting 100 in communication with hopper fuel tank 14, a
hollow vent line 102
extending away from the vent fitting and being coupled to the exterior of
aircraft 12. Vent 96 for
secondary bulkhead 43 also includes one or more vent fittings 100 and vent
lines 102. In
addition, a space 104 between a lower fuselage portion 106 of fuselage 24 and
the top portion 52
of reservoir 50 includes reservoir vent 98, one or more vent fittings 100 and
vent lines 102. Vent
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fittings 100 may be made of any suitable material including, without
limitation, Teflon material
available from E. I. du Pont de Nemours and Company of Wilmington, Delaware.
Vent lines
102 may be made from nylon, such as 1/4 inch nylon tubing. Vent system 20 also
includes at least
one vent valve 36 (Fig. 2) and a pressure relief valve 38 (Fig. 2) coupled to
each of hopper fuel
tank 14 and reservoir 50. Vent valve 36 and pressure relief valve 38 each open
at a
predetermined pressure. Vent system 20 may further include a suction relief
valve such as
suction valve 66 (Fig. 7). Vent system 20 prevents the buildup of either
positive and negative air
pressure in fuel tank 14 and reservoir 50 due to fuel expansion and
contraction due to changes in
temperature, and due to changes in the altitude of aircraft 12.
[0037] Referring now to Figs. 1, 7 and 11, fuel cargo offload subsystem 22
includes a
hopper fuel tank offload valve 108 in communication with hopper fuel tank 14.
Fuel cargo
offload subsystem 22 further includes a reservoir offload valve 110 in
communication with
reservoir 50. Each of valves 108, 110 includes a hose coupler 112. Coupler 112
facilitates the
selectable attachment of a fuel hose (not shown) for removal of fuel from
hopper fuel tank 14 and
reservoir 50. An offload valve control linkage 114, which extends to pilot
compartment 26 (Fig.
1) selectably controls the opening of valves 108, 110.
[0038] With reference to Figs. 1, 3, 4 and 12, in some embodiments hopper fuel
tank
14 may include one or more vapour barriers 116 between a lower portion 118 of
the fuel tank and
lower fuselage portion 106. Vapour barriers 116 surround a space between lower
fuel tank
portion 118 and lower fuselage portion 106 to prevent fume from entering
fuselage 24. Vapour
barriers may be made from cloth conforming to specification MIL-PRF-20696F.
Other materials
may include, without limitation, rubber, EPDM, nitrile, buna, neoprene,
flexible graphite,
silicone, metal, mica, felt, plastic polymer such as Teflon (PTFE), urethane,
and ethylene
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propylene (EP). Vapour barriers 116 may be made from sheet material or may be
applied as a
liquid gasket, as appropriate to the material selected.
[0039] Referring now to Figs. 1 through 12 together, in operation, flammable
liquids
such as fuel may be loaded into either or both hopper fuel tank 14 or
reservoir 50 by removing
the appropriate filler cap 34 (Fig. 2). A fuel hose is inserted into a select
fill port 32. Venting
during the load operation is accomplished though fill port 32. After aircraft
12 has reached its
offload point appropriate fuel offload hoses (not shown) are coupled to hose
couplers 112 (Fig.
11). Offload valve control linkage 114 is actuated, opening valves 108, 110 to
drain tank 14 and
reservoir 50. If an external pump (not shown) is used for offloading fuel, it
is preferable that
caps 34 be removed first, to allow for adequate venting of tank 14 and
reservoir 50 during the
offloading operation. If caps 34 are not removed before pumping fuel from tank
14 and reservoir
50 suction valves 66 (Fig. 7) may open due to the resulting negative pressure
in the tank and/or
reservoir. Similarly, pressure relief valves 38 will open in the event that a
fill pump is
inadvertently connected to hose couplers 112 with fill caps 34 installed.
[0040] System 10 may carry a variety of flammable liquids within the scope of
the
invention including, without limitation, aviation fuel, jet fuel, automobile
fuel, kerosene and
diesel fuel.
[0041] System 10 further includes a landing gear 120, shown in Figs. 1 and 5.
Landing gear 120 is sized and shaped, and made of a select material to allow
aircraft 12 to bear
the weight of flammable liquids stored in hopper fuel tank 14 and reservoir 50
during all flight
phases, including takeoff and landing. This is in contrast to typical aircraft
operations where the
aircraft takes off with a full load of fuel but consumes a significant portion
of the fuel prior to
landing. In one embodiment of the present invention landing gear 120 is made
of spring steel.
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[0042] Aircraft 12 may further include large tundra-type tires 122, shown in
Figs. 1
and 5. Tundra tires 122 allow aircraft 12 to operate from unimproved surfaces
such as dirt, grass
and gravel.
[0043] While this invention has been shown and described with respect to a
detailed
embodiment thereof, it will be understood by those skilled in the art that
changes in form and
detail thereof may be made without departing from the scope of the claims of
the invention.
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