U.S. patent application number 17/233781 was filed with the patent office on 2021-08-05 for controlling lifting gas in inflatable structures.
The applicant listed for this patent is LTAG SYSTEMS LLC. Invention is credited to Alexander H. SLOCUM, Jonathan T. SLOCUM.
Application Number | 20210237843 17/233781 |
Document ID | / |
Family ID | 1000005524835 |
Filed Date | 2021-08-05 |
United States Patent
Application |
20210237843 |
Kind Code |
A1 |
SLOCUM; Alexander H. ; et
al. |
August 5, 2021 |
CONTROLLING LIFTING GAS IN INFLATABLE STRUCTURES
Abstract
Devices, systems, and methods are directed to controlling
lifting gas in a volume defined by an inflatable structure of an
aircraft. For example, controlling lifting gas in the volume of the
inflatable structure may account for variations in ambient and
tactical conditions experienced by the aircraft over the course of
flight, as may be useful for lifting the aircraft to a target
altitude and/or carrying out a particular mission. Additionally, or
alternatively, controlling lifting gas in the volume of the
inflatable structure may facilitate lifting the aircraft using
lifting gas generated by reacting stable materials with one another
at a launch site in the field. As an example, aluminum may react
with water to form a lifting gas including hydrogen and steam. As
the steam condenses to water in the inflatable structure, a valve
may expel water from the inflatable structure to assist in
maintaining buoyancy of the aircraft.
Inventors: |
SLOCUM; Alexander H.; (Bow,
NH) ; SLOCUM; Jonathan T.; (Bow, NH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LTAG SYSTEMS LLC |
Bow |
NH |
US |
|
|
Family ID: |
1000005524835 |
Appl. No.: |
17/233781 |
Filed: |
April 19, 2021 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
17014593 |
Sep 8, 2020 |
|
|
|
17233781 |
|
|
|
|
62897349 |
Sep 8, 2019 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B64B 1/70 20130101; B64B
1/62 20130101; B64B 1/40 20130101; B64B 1/64 20130101 |
International
Class: |
B64B 1/62 20060101
B64B001/62; B64B 1/70 20060101 B64B001/70; B64B 1/64 20060101
B64B001/64; B64B 1/40 20060101 B64B001/40 |
Claims
1. An aircraft comprising: an inflatable structure defining a
volume; a nozzle defining an exit, the nozzle in fluid
communication with the volume; an igniter in a vicinity of the exit
of the nozzle; and a payload coupled to the inflatable structure,
the payload including a strategic portion and a controller, the
strategic portion of the payload at least partially exposed to an
environment outside of the volume, and the controller configured to
actuate the nozzle to issue a lifting gas from the volume in a
direction from the exit toward at least the strategic portion of
the payload, and to actuate the igniter to ignite a combustible
mixture including the lifting gas directed from the exit of the
nozzle.
2. The aircraft of claim 1, wherein the nozzle includes a mixing
section in fluid communication with the exit of the nozzle, and the
mixing section defines at least one orifice through which air in
the environment is movable into the mixing section to mix with the
lifting gas from the volume upon actuation of the nozzle.
3. The aircraft of claim 1, wherein the payload further comprises a
sensor, and the controller is further configured to receive a
signal from the sensor and to actuate at least one of the nozzle or
the igniter based on the signal from the sensor.
4. The aircraft of claim 3, wherein the sensor includes one or more
of an altimeter, a thermocouple, a timer, or a global positioning
system receiver.
5. The aircraft of claim 3, wherein the sensor includes a wireless
communication receiver configured to receive a remote signal from a
remote source.
6. The aircraft of claim 3, wherein the payload further comprises a
transmitter, and the controller is further configured, based on the
signal from the sensor, to activate the transmitter to transmit
data from the strategic portion of the payload to a remote
entity.
7. The aircraft of claim 6, wherein the transmitter is a
line-of-sight data transmitter.
8. The aircraft of claim 6, wherein the transmitter is configured
for encrypted communication.
9. The aircraft of claim 1, wherein the igniter is a spark
igniter.
10. A controller for controlling an aircraft including an
inflatable structure, the controller comprising: a processing unit;
and one or more non-transitory computer storage media in electrical
communication with the processing unit, the one or more
non-transitory computer storage media having stored thereon
instructions that, when executed by the processing unit, cause the
processing unit to carry out operations including receiving a
signal from a sensor, based on the signal from the sensor,
controlling a flow of a lifting gas from a volume of the inflatable
structure through a nozzle directed toward a strategic portion of a
payload coupled to the inflatable structure, and based on the
signal from the sensor, actuating an igniter to ignite a
combustible mixture including the lifting gas moving through the
nozzle.
11. The controller of claim 10, wherein the signal from the sensor
includes one or more of an altitude, a temperature, a time, or
coordinates.
12. The controller of claim 10, wherein the signal from the sensor
includes a remote signal from a remote source.
13. The controller of claim 10, wherein the instructions that, when
executed by the processing unit, cause the processing unit to carry
out controlling the flow of the lifting gas includes actuating a
control valve of the nozzle.
14. The controller of claim 10, wherein the one or more
non-transitory storage media have further stored thereon
instructions that, when executed by the processing unit, cause the
processing unit to carry out an operation including activating a
transmitter to transmit data from the strategic portion of the
payload of the inflatable structure to a remote entity.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 17/014,593, filed on Sep. 8, 2020, which claims the
benefit of priority of U.S. Provisional Patent Application No.
62/897,349, filed on Sep. 8, 2019, with the entire contents of each
of these applications incorporated herein by reference.
BACKGROUND
[0002] Inflatable aircraft can be filled with a lifting gas such
that the average density of the inflatable aircraft is less than
that of ambient air around the aircraft. The resulting buoyancy
allows the inflatable aircraft to rise or float in the ambient air,
making it useful in a variety of dirigible and non-dirigible
applications. When desirable, the buoyancy of the aircraft can
become neutrally buoyant to allow the aircraft to hover. As an
example, inflatable aircraft in the form of weather balloons are
commonly used for meteorological observation of localized
conditions that may not be accurately measurable using ground-based
measurements or satellite images.
[0003] While lifting gas is a reliable way to impart at least a
degree of buoyancy to an inflatable aircraft, the composition of
the lifting gas can limit the effectiveness--or even the
viability--of the inflatable aircraft for a particular mission. For
example, helium is inert and has low density relative to air (and,
thus, high lifting capacity). As a non-renewable resource, however,
helium is subject to price spikes resulting from shortages and must
be stored and transported in compressed gas cylinders. Thus, helium
presents logistical challenges for launching inflatable aircraft
from remote or poorly resourced locations. Helium is also a
critical inert gas for the semi-conductor industry, and thus is not
capable of sustaining a balloon market that is growing. As another
example, hydrogen offers about eight percent more lift than helium
and can be cost-effectively formed on a commercial scale using a
variety of techniques, including from renewable resources. Given
its wide flammability limits in the presence of air, however,
hydrogen is dangerous to store and transport, thus presenting
safety challenges for transport and use in uncontrolled
environments.
[0004] Accordingly, there remains a need for controlling lifting
gas to achieve robust performance of inflatable aircraft over a
wide range of environmental conditions while using resources
compatible with field deployment.
SUMMARY
[0005] Devices, systems, and methods are directed to controlling
lifting gas in a volume defined by an inflatable structure of an
aircraft. For example, controlling lifting gas in the volume of the
inflatable structure may account for variations in ambient and
tactical conditions experienced by the aircraft over the course of
flight, as may be useful for lifting the aircraft to a target
altitude and/or carrying out a particular mission. Additionally, or
alternatively, controlling lifting gas in the volume of the
inflatable structure may facilitate lifting the aircraft using
lifting gas generated by reacting stable materials with one another
at a launch site in the field. As an example, aluminum may react
with water to form a lifting gas including hydrogen and steam. The
steam can give the aircraft additional lift from the ground, thus
reducing the total amount of hydrogen gas needed to keep the
aircraft afloat at higher altitudes. As the steam condenses to
water in the inflatable structure, a valve may expel water from the
inflatable structure to assist in maintaining buoyancy of the
aircraft.
[0006] According to one aspect, an aircraft system may include an
inflatable structure defining a volume configured to receive a
lifting gas, and a drain valve coupled to the inflatable structure
and disposed relative to the volume to collect condensate, in the
volume, from the lifting gas received into the volume, the drain
valve controllable to expel the condensate from the volume while
maintaining a substantially gas-tight seal between the volume and
an environment outside of the volume.
[0007] In some implementations, the inflatable structure may
include a balloon at least partially defining the volume, and the
balloon is formed of one or more of a compliant material or a
semi-compliant material.
[0008] In certain implementations, the drain valve may be disposed
relative to the volume of the inflatable structure in an
orientation in which the condensate in the volume is movable toward
the drain valve under gravitational force. Additionally, or
alternatively, the drain valve may include a float valve. Further,
or instead, the inflatable structure may further include a ballast
section disposed relative to the drain valve in an orientation in
which the condensate in the volume collects in the ballast section
as the condensate moves toward the drain valve under gravitational
force. The drain valve may be controllable to retain a
predetermined amount of condensate in the ballast section to
ballast the inflatable structure and expel an excess amount of
condensate from the volume while maintaining a substantially
gas-tight seal between the volume and the environment outside of
the volume.
[0009] In some implementations, the aircraft system may further
include a reactor defining a chamber, an inlet region, and an
outlet region. The inlet region and the outlet region may be, for
example, in fluid communication with one another and with the
chamber. Additionally, or alternatively, the inlet region may be
releasably securable in fluid communication with a fluid source,
and the lifting gas may be receivable into the volume via fluid
communication between the volume of the inflatable structure and
the outlet region of the reactor. In some instances, at least a
portion of the reactor may be mechanically securable to the
inflatable structure to be movable with the inflatable structure
during flight. Additionally, or alternatively, the aircraft system
may include a condenser and a container in fluid communication with
each other. For example, the container may be in fluid
communication with the chamber of the reactor. Additionally, or
alternatively, the condenser may be configured to return at least
some of the fluid from the condenser to the container while the
inflatable structure is in fluid communication with the outlet
region of the reactor. Further, or instead, the aircraft system may
include a first heat exchanger in thermal communication with the
condenser. Still further, or instead, the aircraft system may
include a second heat exchanger in thermal communication with the
chamber of the reactor. Yet further, or instead, the aircraft
system may further include a swirl separator arranged to separate
at least one heavier component from at least one lighter component
in a flow of lifting gas from the outlet region of the reactor and
direct the remaining lifting gas from the swirl separator toward
the volume of the inflatable structure. Additionally, or
alternatively, the aircraft system may include an auxiliary gas
source in fluid communication with the volume of the inflatable
structure to mix an auxiliary gas from the auxiliary gas source
with the lifting gas receivable into the volume from the outlet
region of the reactor. For example, a flow rate of the auxiliary
gas from the auxiliary gas source may be adjustable to control a
ratio of the auxiliary gas to the lifting gas receivable into the
volume of the inflatable structure.
[0010] According to another aspect, a computer program product may
be encoded on one or more non-transitory computer storage media,
the computer program product comprising instructions that, when
executed by one or more computing devices, may cause the one or
more computing devices to perform operations including receiving
input including a target altitude for an aircraft including an
inflatable structure defining a volume, based on the input,
determining a target density of a lifting gas in the volume
according to a model stored on the one or more non-transitory
computer storage media, receiving, from a temperature sensor, a
first signal indicative of temperature of the lifting gas in the
volume, receiving, from a pressure sensor, a second signal
indicative of pressure of the lifting gas in the volume, based on
the first signal, the second signal, and the target density,
controlling a flow of the lifting gas into the volume from a source
in fluid communication with the volume. As an example, the input
may include atmospheric conditions at a launch location, the target
altitude, or a combination thereof.
[0011] In certain implementations, the instructions, when executed
by one or more computing devices, may cause the one or more
computing devices to perform the further operations of receiving,
from a motion sensor, a third signal indicative of movement of the
inflatable structure and, based on the third signal, selectively
controlling actuation of a drain valve in fluid communication with
the volume of the inflatable structure such that moisture condensed
in the volume is selectively released from the inflatable structure
to ballast the inflatable structure.
[0012] According to still another aspect, an aircraft may include
an inflatable structure defining a volume, a nozzle defining an
exit, the nozzle in fluid communication with the volume, an igniter
in a vicinity of the exit of the nozzle, and a payload coupled to
the inflatable structure. The payload may include a strategic
portion and a controller. As an example, the strategic portion of
the payload may be at least partially exposed to an environment
outside of the volume. Additionally, or alternatively, the
controller may be configured to actuate the nozzle to issue a
lifting gas from the volume in a direction from the exit toward at
least the strategic portion of the payload, and to actuate the
igniter to ignite a combustible mixture including the lifting gas
directed from the exit of the nozzle toward one or more of the
inflatable structure or the strategic portion of the payload.
[0013] In certain implementations, the nozzle may include a mixing
section in fluid communication with the exit of the nozzle. The
mixing section may, for example, define at least one orifice
through which air in the environment is movable into the mixing
section to mix with the lifting gas from the volume upon actuation
of the nozzle.
[0014] In some implementations, the payload may, additionally or
alternatively, include a sensor, and the controller the controller
may be configured to receive a signal from the sensor and to
actuate at least one of the nozzle or the igniter based on the
signal from the sensor. Examples of the sensor include, but are not
limited to, one or more of an altimeter, a thermocouple, a timer, a
global positioning system receiver, or a wireless communication
receiver.
[0015] In certain implementations, the payload may further, or
instead, include a transmitter, and the controller may be
configured, based on the signal from the sensor, to activate the
transmitter to transmit data from the strategic portion of the
payload to a remote entity.
BRIEF DESCRIPTION OF THE FIGURES
[0016] FIG. 1A is a schematic representation of an aircraft system
including an aircraft and a delivery system, with the aircraft
shown coupled to the delivery system to receive lifting gas from
the delivery system.
[0017] FIG. 1B is a cross-sectional side view of an inflatable
structure of the aircraft of FIG. 1A, the cross-section taken along
the line 1B-1B in FIG. 1A.
[0018] FIG. 1C is a cross-sectional side view a drain valve of the
aircraft of FIG. 1A, shown along the area of detail 1C in FIG.
1B.
[0019] FIG. 1D is a schematic representation of the aircraft system
of FIG. 1A, with the aircraft shown decoupled from the delivery
system.
[0020] FIG. 2 is a flowchart of an exemplary method of controlling
lift of an aircraft propelled by buoyancy of a lifting gas.
[0021] FIG. 3 is a schematic representation of an aircraft system
including a delivery system having a condenser.
[0022] FIG. 4 is a schematic representation of an aircraft system
including delivery system having an auxiliary gas.
[0023] FIG. 5A is a schematic representation of an aircraft system
including a delivery system having a reactor with a removable
liner.
[0024] FIG. 5B is a schematic representation of the removable liner
of FIG. 5A tethered to an aircraft of the aircraft system of FIG.
5A.
[0025] FIG. 6 is a schematic representation of an aircraft system
including a delivery system having a compressed gas cylinder as a
source of a lifting gas.
[0026] FIG. 7 is a schematic representation of an aircraft
including a nozzle and igniter directed toward a payload of an
inflatable structure.
[0027] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION
[0028] The embodiments will now be described more fully hereinafter
with reference to the accompanying figures, in which exemplary
embodiments are shown. The foregoing may, however, be embodied in
many different forms and should not be construed as limited to the
exemplary embodiments set forth herein.
[0029] All documents mentioned herein are hereby incorporated by
reference in their entirety. References to items in the singular
should be understood to include items in the plural, and vice
versa, unless explicitly stated otherwise or clear from the text.
Grammatical conjunctions are intended to express any and all
disjunctive and conjunctive combinations of conjoined clauses,
sentences, words, and the like, unless otherwise stated or clear
from the context. Thus, the term "or" should generally be
understood to mean "and/or," and the term "and" should generally be
understood to mean "and/or."
[0030] Recitation of ranges of values herein are not intended to be
limiting, referring instead individually to any and all values
falling within the range, unless otherwise indicated herein, and
each separate value within such a range is incorporated into the
specification as if it were individually recited herein. The words
"about," "approximately," or the like, when accompanying a
numerical value, are to be construed as including any deviation as
would be appreciated by one of ordinary skill in the art to operate
satisfactorily for an intended purpose. Ranges of values and/or
numeric values are provided herein as examples only, and do not
constitute a limitation on the scope of the described embodiments.
The use of any and all examples or exemplary language ("e.g.,"
"such as," or the like) is intended merely to better illuminate the
embodiments and does not pose a limitation on the scope of those
embodiments. No language in the specification should be construed
as indicating any unclaimed element as essential to the practice of
the disclosed embodiments.
[0031] In the description that follows, of aircraft of various
implementations of devices, systems, and methods are generally
described with respect to balloons, given that balloons are an
important application for lifting gas and serve as useful examples
for highlighting particular aspects of the devices, systems, and
methods of the present disclosure. That is, it shall be understood
that, to the extent aircraft are described herein as including
aspects of balloons, this is for the sake of clear and efficient
description and should not be considered limiting. Thus, unless
otherwise specified or made clear from the context, the term
"aircraft" shall be understood to include any manner and form of
object that can receive lifting gas to have at least some degree of
buoyancy in ambient air, whether in an indoor or an outdoor
environment. In use, such aircraft may be used to make observations
(e.g., about weather in the atmosphere, conditions of terrain below
the aircraft), carry passengers and/or cargo, broadcast and/or
receive signals beyond the aircraft, collect data, lift structures,
or serve as decorations. Accordingly, as used herein, aircraft may
include any one or more of various different manned or unmanned
craft, dirigible or non-dirigible craft, independently propelled or
floating craft, rigid or nonrigid craft, tethered or untethered
craft, or combinations thereof. Some examples of aircraft,
therefore, may include, but are not limited to any manner and form
of aerostats, balloons, or other rigid, semi-rigid, or non-rigid
inflatable structures.
[0032] As used herein, the term "gas" or variants thereof (e.g.,
lifting gas) shall be understood to include a single component or
multiple components (mixed), unless otherwise specified or made
clear from the context. Further, unless a contrary intent is
indicated, the use of the term gas shall be generally understood to
include any multi-phase mixture that includes one or more gas phase
components and exhibits characteristics of a compressible fluid,
with a relationship between pressure, volume, and temperature that
is accurately characterized by the ideal gas law to within about
.+-.5 percent at room temperature at sea level. Thus, for example,
a gas may include at least one gas phase component, as well as some
amount of one or more vapor components (e.g., water vapor).
[0033] As also used herein, unless otherwise specified or made
clear from the context, the term "lift capacity" shall be
understood to be interchangeable with buoyancy with respect to air
and is express as follows:
F.sub.B=(.rho..sub.air-.rho..sub.gas)*g* V [Eq. 1]
where F.sub.B is buoyancy force, .rho..sub.air is the density of
air in the environment outside of the aircraft, .rho..sub.gas is
the density of the lifting gas in the aircraft, g is the force of
gravity, and V is the volume of air displaced by the lifting gas.
That is, lift capacity shall be understood to be the force
available for the lifting gas to impart to the aircraft at any
given point in time. Accordingly, as may be readily appreciated, in
instances in which the lift capacity of the lifting gas carried in
an aircraft is greater than the weight of the aircraft (including
the lifting gas and payload), the aircraft will ascend. Similarly,
in instances in which the lift capacity of the lifting gas carried
in the aircraft is less than the weight of the aircraft (including
the lifting gas and payload), the aircraft will descend.
[0034] Referring now to FIGS. 1A-1D, an aircraft system 100 may
include an aircraft 102 and a delivery system 104 releasably
securable in fluid communication with one another. In general, the
aircraft 102 may include an inflatable structure 106 defining a
volume 108. In use, as described in greater detail below, the
delivery system 104 may form a lifting gas 109 received into the
volume 108 in an amount sufficient to impart the aircraft 102 with
an average density less than that of air in the environment outside
of the volume 108 (e.g., such that the aircraft 102 has a
predetermined amount of buoyancy), and the aircraft 102 may then be
decoupled from the delivery system 104 to carry out a particular
mission. As also described in greater detail below, the lifting gas
109 formed by the delivery system 104 may include a mixture of
hydrogen and steam, each of which is useful for imparting buoyancy
to the aircraft 102 under appropriate atmospheric conditions.
However, as atmospheric conditions change about the aircraft 102
(e.g., decreasing pressure and temperature as the aircraft 102
floats to increasing altitude, heat transfer to the environment, or
a combination thereof), at least a portion of the steam in the
lifting gas 109 in the volume 108 may condense to form a condensate
111 in the volume 108. The condensate 111 may be, for example,
water condensed from steam in the volume 108, any byproduct of a
reaction carried out in the delivery system 104 and condensed in
the volume 108, or a combination thereof. As compared to steam,
which provides lift, the condensate 111 in the volume 108 does not
provide lift and, thus, the weight of the condensate 111
counteracts buoyancy forces provided by the hydrogen and any
remaining steam in the lifting gas 109. Thus, the aircraft 102 may
additionally, or alternatively, include a drain valve 110 coupled
to the inflatable structure 106 and disposed relative to the volume
108 to collect moisture condensed in the volume 108 from the
lifting gas 109 received into the volume 108 from the delivery
system 104. As also described in greater detail below, the drain
valve 110 may be controllable to expel the condensate 111 from the
volume 108 to facilitate making efficient use of the buoyancy force
provided by the lifting gas 109 remaining the volume 108. That is,
draining at least a portion of the condensate 111 from the volume
108 via the drain valve 110 may facilitate achieving higher
altitudes as compared to similarly sized aircraft under otherwise
identical conditions.
[0035] In general, the drain valve 110 may be disposed relative to
the volume 108 defined by the inflatable structure 106 in any one
or more of various different orientations suitable for achieving
fluid communication between the drain valve 110 and the volume 108.
Thus, in certain implementations, the drain valve 110 may be at
least partially disposed within the inflatable structure 106. Such
positioning of the drain valve 110 may useful for, among other
things, achieving low volumes of the condensate 111 required to
actuate the drain valve 110, reducing the likelihood of damage to
the drain valve 110 during flight, and reducing the amount of heat
lost from the volume 108 to the environment, via the drain valve
110. In some implementations, however, the drain valve 110 may be
mechanically coupled to the outside of the inflatable structure 106
and, thus, outside of the volume 108, as may be useful for
facilitating repairing and/or replacing the drain valve 110 in the
field.
[0036] Additionally, or alternatively, whether the drain valve 110
is at least partially disposed within or outside of the inflatable
structure 106, the drain valve 110 may be disposed relative to the
volume 108 of the inflatable structure 106 such that the condensate
111 condensed in the volume 108 is movable toward the drain valve
110 by gravitational force. As may be appreciated, movement of the
condensate 111 toward the drain valve 110 under gravitational force
may be particularly advantageous for achieving lightweight
construction of the aircraft 102, as compared to the use of a pump
or other mechanical equipment that adds weight to the aircraft 102.
Further, or instead, orienting the drain valve 110 to receive the
condensate 111 through gravitational force may facilitate achieving
robust performance of the aircraft 102. For example, as compared to
the use of pumps, the use of relative orientation of the drain
valve 110 to the volume 108 to move the condensate 111 to the drain
valve 110 may have fewer failure modes and/or may be more resilient
to changing or unpredictable conditions encountered by the aircraft
102 while in flight. To the extent a reaction byproduct in solid or
liquid form is carried into the volume 108, it shall be appreciated
that the condensate 111 formed in the volume 108 may mix with the
solid or liquid byproduct and, thus, carry the solid or liquid
byproduct out of the volume 108 through the drain valve 110,
reducing the weight of the aircraft 102. Thus, unless otherwise
specified or made clear from the context, any description of
condensate 111 herein shall be understood to include any condensate
formed in the volume, as well as material that may flow along with
the condensate.
[0037] In general, the drain valve 110 may be controllable to expel
the condensate 111 from the volume 108 of the inflatable structure
106 while maintaining a substantially gas-tight seal between the
volume 108 and an environment (e.g., ambient environment) outside
of the volume 108. As used in this context, a substantially
gas-tight seal shall be understood to be any seal that results in
less than about 1 percent of the volume of the lifting gas 109
escaping from the volume 108 via the drain valve 110. That is,
importantly, the drain valve 110 may remove weight--in the form of
the condensate 111 being expelled--from the volume 108 with little
or no resulting impact on the lift capacity provided by the lifting
gas 109 in the volume 108, even as the drain valve 110 moves from a
closed position to an open position and back to the closed position
to expel the moisture. In doing so, it shall be understood that the
drain valve 110 may improve the overall lift performance of the
aircraft 102 during the course of flight, as compared to the lift
performance of the aircraft 102 immediately prior to expelling the
condensate 111 from the volume 108 of the inflatable structure 106.
In certain instances, condensation of the condensate 111 from the
lifting gas 109 in the volume 108 may be the result of unexpected
conditions encountered by the aircraft 102 and, thus, action of the
drain valve 110 to expel the condensate 111 from the volume 108 may
facilitate making the aircraft 102 more robust with respect to
achieving target altitudes. Further, or instead, the drain valve
110 may facilitate achieving target altitudes using a range of
compositions of the lifting gas 109--thus, for example, reducing
the need for tight control over composition of the lifting gas 109
and facilitating production of the lifting gas 109 at the launch
site, using a combination of portable and locally available
resources, as described in greater detail below.
[0038] In certain implementations, returning to the example of the
drain valve 110 receiving the condensate 111 via gravitational
force, the drain valve 110 may include a float valve 112 having a
ball float 114, a body 116, and a piston 118. The ball float 114
may be coupled to the body 116 at a hinge 120, with the ball float
114 pivotable about the hinge 120 in response to changes in a level
of the condensate 111 rises in the volume 108. The hinge 120 may be
mechanically coupled to the piston 118, and the pivoting movement
of the ball float 114 about the hinge 120 may move the piston 118
up and down within the body 116. For example, in the orientation
shown in the figures, as the ball float 114 moves upward in
response to an increase in a level of the condensate 111 in the
volume 108, the hinge 120 may rotate counterclockwise to move the
piston 118 away from a seat 122, thus allowing some of the
condensate 111 to be expelled from the volume 108 as is desirable
for achieving efficient use of the lift capacity of the lifting gas
109 remaining in the volume 108. As some of the condensate 111 is
expelled from the volume 108 and the level of the moisture
remaining in the volume 108 decreases, the ball float 114 may move
downward such that the hinge 120 may rotate clockwise to move the
piston 118 into engagement with the seat 122, thus closing the
float valve 112.
[0039] Importantly, as may be appreciated from the foregoing
description, the float valve 112 may be particularly effective in
maintaining a substantially gas-tight seal between the volume 108
and an environment outside of the volume 108 as the float valve 112
is open and closed to drain some of the condensate 111 from the
volume 108. That is, throughout operation of the float valve 112 at
least some of the condensate 111 may remain between the lifting gas
109 in the volume 108 and the environment outside of the volume 108
when the piston 118 is moved away from the seat 122. Stated
differently, by allowing some of the condensate 111 to remain in
the volume 108 between the lifting gas 109 and the seat 122 as the
float valve 112 is open and closed, the float valve 112 may be
controllable to remove some of the condensate 111 from the volume
108 while the condensate 111 remaining in and/or around the float
valve 112 itself maintains the substantially gas-tight seal between
the volume 108 and the environment outside of the volume 108.
[0040] While a specific configuration of the float valve 112 has
been described, it shall be understood that this is for the purpose
of clear and efficient description of certain aspects of float
valve operation in the context of controlling moisture in the
inflatable structure 106. Thus, more generally, it shall be
understood the float valve 112 may be any one or more of various
different mechanical valves controllable by a float element
responsive to a change in level of the condensate 111 to open and
close the float valve 112 to expel some of the condensate 111 from
the volume 108 while the remainder of the condensate 111 may
facilitate maintaining the substantially gas-tight seal between the
volume 108 and the environment outside of the volume 108 throughout
operation of the float valve 112. As may be appreciated, the
mechanical and self-controlling nature of the float valve 112 may
be robust over a range of conditions both inside and outside of the
volume 108 during inflation of the inflatable structure 106 and/or
during flight of the aircraft 102 while being lightweight and
inexpensive, as compared to valves based on electronic sensing,
actuation, or a combination thereof. Further, or instead, as
described in greater detail below, the mechanical and robust nature
of the float valve 112 suitable for withstanding the lifting gas
109 may facilitate delivering the lifting gas 109 into the volume
108 of the inflatable structure 106. By eliminating the need
separate sites of ingress into and egress out of the inflatable
structure 106, the float valve 112 serving to both fill and empty
the volume 108 of the inflatable structure may reduce the number of
potential sources of inadvertent leakage out of the volume 108,
thus improving overall integrity of the aircraft 102. While
electronic sensing, actuation, or a combination thereof may have
limited usefulness in certain implementations of the drain valve
110, as described above, it shall be appreciated that such
electronic sensing, actuation, or a combination thereof may be
useful in the drain valve 110 in instances benefiting from
sophisticated control (e.g., on-demand) over expulsion of the
condensate 111 from the volume 108.
[0041] In general, the inflatable structure 106 may be formed
according to any one or more of various different form factors
suitable for a particular use case of the aircraft 102. That is,
stated in terms of buoyancy, the inflatable structure 106 may be
formed of any one or more of various different materials and
according to any one or more of various different shapes, provided
that the volume 108 defined by the inflatable structure 106 is
sized to receive a suitable volume of a predetermined lifting gas
having a lifting capacity (buoyancy force per unit volume)
appropriate for lifting the weight of the aircraft 102 (including
any payload intended to be carried by the aircraft 102) to a target
altitude. In certain instances, the form factor of the inflatable
structure 106 may be additionally, or alternatively, constrained
based on logistical considerations, such as those associated with
storing the aircraft 102 and/or the type of transport available to
move the aircraft 102 to a launch site.
[0042] As an example, given the trade-off between weight and
overall size of the inflatable structure 106, implementations of
the inflatable structure 106 for observation missions may be formed
of any combination of materials that collectively facilitate
floating the aircraft 102 to a target altitude (e.g., between about
1 km and about 30 km) while maintaining the overall size of the
aircraft 102, in an uninflated state, within a size and weight
envelope amenable to portability by passenger vehicle or, in some
case, by an individual. Additionally, or alternatively, the
material forming the inflatable structure 106, at least along the
volume 108, may be substantially impermeable to diffusion of the
lifting gas 109 through the material defining the inflatable
structure 106, at least along the volume 108, to facilitate
efficiently imparting lift force from the lifting gas 109 to the
aircraft 102. In this context, a material or combination of
materials having substantial impermeability to diffusion of the
lifting gas 109 shall be understood to include latex, neoprene, or
any one or more of various different materials for which the
diffusion rate of hydrogen is less than or equal to the diffusion
rate of hydrogen through latex or neoprene, under otherwise
identical conditions.
[0043] In some instances, to facilitate movement of the condensate
111 toward the drain valve 110, the material forming the inflatable
structure 106 may be substantially hydrophobic at least along the
volume 108. As shall be appreciated, in instances in which the
inflatable structure 106 is formed of substantially hydrophobic
material at least along the volume 108, the inflatable structure
106 generally does not absorb the condensate 111 before the
condensate 111 can reach the drain valve 110. That is, the use of
substantially hydrophobic material may facilitate efficient removal
of the condensate 111 from the volume 108. In this context, a
material or combination of materials that are substantially
hydrophobic shall be understood to include latex, neoprene,
polyester, or any one or more of various different materials having
at least the same hydrophobicity as latex, neoprene, or polyester,
under otherwise identical conditions.
[0044] By way of example and not limitation, the inflatable
structure 106 may include a balloon 124, as may be particularly
useful for implementations related to unmanned observation. That
is, being a bluff body, the balloon 124 may be effectively driven
by prevailing winds, without the need for separate propulsion.
Additionally, or alternatively, the balloon 124 may have
substantially rounded outer edges to reduce the likelihood of
becoming snagged on impediments in the path of the inflatable
structure 106 and/or to reduce the likelihood of creating a hazard
to property or individuals on the ground as the aircraft 102
descends. Further, or instead, the balloon 124 may reduce or
eliminate the need for seams that may otherwise compromise the
ability of the inflatable structure 106 to contain the lifting gas
at high pressures useful for achieving high altitude.
[0045] In certain instances, the balloon 124 may include a
compliant material (e.g., one or more of latex or neoprene), as may
be useful for efficiently storing the inflatable structure 106 when
it is not in use. Additionally, or alternatively, in some
instances, the balloon may include a semi-compliant material, such
as may be useful for imparting a high strength-to-weight ratio to
the inflatable structure 106. Such a high strength-to-weight ratio
of the inflatable structure 106 may be particularly useful, for
example, in instances in which the lifting gas 109 includes
hydrogen and safety considerations warrant the use of material
offering a high amount of resistance to puncture, abrasion, or
other types of degradation that may result in inadvertent escape of
the hydrogen. As an example, the semi-compliant material may
include woven from filaments of one or more thermoplastic polymers,
with the compliance of the semi-compliant material changing as the
thermoplastic polymers are heated and cooled during preparation and
flight of the aircraft 102.
[0046] The inflatable structure 106 may, in some implementations,
include a ballast section 126 to facilitate providing stability to
the aircraft 102, as may be useful for maintaining the aircraft 102
in a particular orientation and/or reducing movement of the
aircraft 102 that may otherwise interfere with measurement
instruments carried by the payload of the aircraft 102. In general,
the ballast section 126 may be disposed relative to the drain valve
110 in an orientation in which the condensate 111 condensed in the
volume 108 collects in the ballast section 126 (e.g., under the
force of gravity) as the condensate 111 moves toward the drain
valve 110. That is, the weight of the condensate 111 collected in
the ballast section 126 may impart stability to the aircraft 102
with respect to lateral forces exerted (e.g., by wind) on the
aircraft 102 in a deployed orientation in which the volume 108 of
the inflatable structure 106 is above the ballast section 126 as
the aircraft 102 is in flight. Thus, for example, the drain valve
110 may be controllable to expel the condensate 111 to ballast the
inflatable structure 106 while maintaining a substantially
gas-tight seal between the volume 108 and the environment outside
of the volume 108 according to any one or more of the various
different techniques described herein. That is, the drain valve 110
may expel an excess amount of the condensate 111 when the
condensate 111 collected in the ballast section 126 is above a
predetermined amount of the condensate 111 useful for providing
ballast associated with a desired amount of stability.
[0047] As may be appreciated from the foregoing, accumulation of
the predetermined amount of the condensate 111 in the ballast
section 126 may occur over time as the aircraft 102 undergoes
flight. Such gradual accumulation of the condensate 111 in the
ballast section 126 may be useful for balancing competing
considerations associated with retaining the condensate 111 to
provide ballast to the aircraft 102 and expelling the condensate
111 to improve buoyancy of the aircraft 102. That is, at lower
altitudes--before a significant amount of the condensate 111 has
accumulated in the ballast section 126--conditions may be calmer
such that less stabilization is generally required. At higher
altitudes--after the predetermined amount of the condensate 111 has
accumulated in the ballast section 126--conditions may be more
turbulent such that the increased stabilization provided by the
predetermined amount of the condensate 111 justifies the weight
associated with carrying the predetermined amount of the condensate
111.
[0048] Returning to the example in which the drain valve 110
includes the float valve 112, the level at which movement of the
ball float 114 moves the piston 118 away from the seat 122 may
correspond to the predetermined amount--and, thus, a predetermined
weight--of the condensate 111 useful for imparting ballast while
having an acceptable impact on lift of the aircraft 102. While the
level of the float valve 112 may be fixed in certain instances such
that the ballast section 126 provides the same amount of ballast
regardless of environmental conditions, it shall be understood that
the level of the float valve 112 may be adjustable according to
environmental conditions. Continuing with this example, the ball
float 114 may be adjustable to a lower level such that a smaller
amount (and, thus, lower weight) of the condensate 111 may be
retained in the ballast section 126 in instances in which
environmental conditions over the expected course of flight of the
aircraft are expected to be calm. In this way, adjustment of the
level of the ball float 114 may be used to arrive at a suitable
ballast level in view of the trade-off between ballast and
achievable altitude of the aircraft 102 under otherwise identical
conditions.
[0049] Having described certain features of the aircraft 102,
attention is turned now to description of the delivery system 104
that may be used to generate the lifting gas 109 and deliver the
lifting gas 109 into the volume 108 to provide buoyancy to the
aircraft 102, with the buoyancy being suitable for a particular
mission intended for aircraft 102. For the sake of clear and
efficient description, the delivery system 104 and the aircraft 102
are described as discrete aspects of the aircraft system 100, with
the aircraft 102 decoupled from the delivery system 104 prior to
flight such that the aircraft 102 does not carry excess weight. It
shall be appreciated, however, that certain portions of the
delivery system 104 may remain coupled to the aircraft 102 during
flight, to the extent there is a benefit in maintaining such
coupling. Specifically, unless otherwise specified or made clear
from the context, electronics (e.g., control system, thermocouples
and/or pressure sensors) used to prepare the aircraft 102 for
flight shall be understood to be permanently coupled or releasably
coupled to the aircraft 102, as may be useful to facilitate launch
and/or monitor conditions in the volume 108 during flight. Further,
in the description that follows, emphasis is generally placed on
aspects of the delivery system 104 that facilitate using the
aircraft system 100 in the field, where conditions and availability
of resources may be unpredictable. It shall be appreciated,
however, that such aspects facilitating use of the aircraft system
100 in the field may be useful for facilitating launches under
controlled and predictable conditions, to the extent that such
aspects improve error tolerance, lower cost, and/or improved
safety.
[0050] In certain implementations, the delivery system 104 may
include a reactor 128 defining a chamber 130, an inlet region 132,
and an outlet region 134. In general, the inlet region 132 and the
outlet region 134 may be in fluid communication with one another
and with the chamber 130. For example, the inlet region 132 may be
in fluid communication with the outlet region 134 via the chamber
130 such that fluid moving into the inlet region 132 must pass
through the chamber 130 before reaching the outlet region 134, as
may be useful for reducing the likelihood of cross-contamination of
inlet streams and outlet streams while being achievable using a
straightforward valving arrangement. As another example, however,
the inlet region 132 and the outlet region 134 may be co-located
with one another relative to the chamber 130, as may be useful for
locating the inlet region 132 and the outlet region 134 on a single
side of the reactor 128--an orientation that may be well-suited for
rapidly setting up and breaking down the delivery system 104 and/or
well-suited for mounting the delivery system 104 within an
available footprint (e.g., on a vehicle).
[0051] In general, at least the portions of the reactor 128
defining the chamber 130 and the outlet region 134 may be formed of
one or more materials that are inert in the presence of the
reactants and the products associated with a chemical reaction in
the chamber 130. Further, or instead, the structural
characteristics of the one or more materials forming the chamber
130 and the outlet region 134 remain otherwise unchanged by
exposure to the temperature and pressure associated with the
chemical reaction in the chamber 130. By way of example, and not
limitation, the chemical reaction in the chamber 130 may include
exposing aluminum to water in a reaction that produces hydrogen,
heat, and one or more aluminum hydroxides. As may be appreciated
from the foregoing example, forming hydrogen and heat (each of
which contribute to lift capacity of the lifting gas 109) in this
way may be particularly advantageous, given that the reactants may
be readily sourced and safe and the only unusable byproduct is
aluminum hydroxide, which is non-toxic and can be recycled or
disposed of safely. A challenge with forming hydrogen and heat in
this way, however, is that a stable oxide coating forms rapidly on
the aluminum, forming a barrier to the aforementioned reaction
between aluminum and water under normal environmental conditions.
Accordingly, the reaction of aluminum and water to produce hydrogen
may be carried out using aluminum that has been treated to overcome
the challenges associated with the oxide coating. As an example,
aluminum that has been treated as described in U.S. Pat. No.
10,745,789, issued on Aug. 18, 2020, and entitled "ACTIVATED
ALUMINUM FUEL," the entire contents of which are hereby
incorporated herein by reference. Thus, continuing with this
example, the one or more materials forming the reactor 128 at least
along the chamber 130 may be any one or more of various different
materials suitable for withstanding exposure to the reaction of
such activated aluminum with water to form hydrogen and heat.
Examples of such material include, but are not limited to, plastic,
stainless steel, glass, or other commonly available and inexpensive
material.
[0052] In certain instances, the inlet region 132 of the reactor
128 may be releasably securable in fluid communication with a fluid
source 136 to introduce at least one reactant into the chamber 130.
In certain implementations, the fluid source 136 may be above the
reactor 128, and the at least one reactant may flow from the fluid
source 136 into the chamber under the force of gravity. The use of
gravity in this way may be useful, for example, reducing or
eliminating pumping requirements in implementations that do not
require precise metering of the at least one reactant in to the
chamber 130. In particular, returning to the example of activated
aluminum fuel, the fluid source 136 may be a source of water.
Advantageously, reaction of the activated aluminum to form hydrogen
does not require any particular water quality, making both fresh
water, brackish, and saltwater sources encountered in the field
useful as the fluid source 136. Combining this feature with the
stability of the active aluminum over a range of conditions and
formability into readily portable form factors (e.g., pellets), it
shall be appreciated that formation of the reactor 128 to
accommodate forming hydrogen from the activated aluminum may be
particularly useful for facilitating portability and usefulness of
the aircraft system 100 in the field. While gravity may be used in
some instances, it shall be appreciated that the fluid source 136
may, additionally or alternatively, include a pump to facilitate
moving the at least one reactant from the fluid source 136 into the
chamber 130.
[0053] The outlet region 134 of the reactor 128 may, in general, be
formed of any one or more materials suitable for withstanding
exposure to the products and temperatures associated with the
reaction in the chamber 130. Additionally, or alternatively, the
outlet region 134 of the reactor 128 may be in gas-tight fluid
communication with the volume 108 of the aircraft 102 to reduce the
likelihood of contaminants into the flow. For example, in instances
in which the flow through the outlet region 134 includes hydrogen,
the gas-tight fluid communication between the outlet region 134 and
the volume 108 of the aircraft 102 may reduce the likelihood of
introducing oxygen into the flow received into the volume 108 of
the aircraft 102 in amounts forming a combustible mixture with the
hydrogen.
[0054] In some implementations, the delivery system 104 may include
an exhaust 138 in fluid communication between the outlet region 134
of the reactor 128 and the volume 108 via the drain valve 110 of
the aircraft 102. In general, the exhaust 138 may be formed of any
one or more of various different types of tubing (e.g., flexible,
rigid, or a combination thereof) suitable for withstanding exposure
to the products and temperatures of the flow from the outlet region
134 of the reactor 128. Additionally, or alternatively, the exhaust
138 may be formed of one or more thermally insulating materials to
reduce unintended heat transfer between the flow in the exhaust 138
and the environment outside of the exhaust 138. Further, or
instead, it shall be understood that the exhaust 138 may be
connected to the outlet region 134 according to any one or more of
various different techniques known for releasably and/or fixedly
connecting tubing to a port or other orifice with a gas-tight
seal.
[0055] In some instances, the flow moving from the outlet region
134 toward the volume 108 via the drain valve 110 of the aircraft
102 may be processed along the exhaust 138, as may be useful for
achieving target parameters of the lifting gas 109 ultimately
received into the volume 108. While such processing is generally
useful for controlling parameters of lifting gas of any provenance,
it shall be appreciated that processing the flow moving along the
exhaust 138 may be particularly useful in instances in which the
lifting gas 109 (or a precursor to the lifting gas 109) is formed
in situ in the chamber 130. That is, in the field, it may be
difficult or undesirable to achieve precise composition of the
components of the flow generated in the chamber 130 and moved,
through the outlet region 134, into the exhaust 138. In some
instances, such imprecision may be particularly challenging when it
is desirable or necessary to use one or more components from a
locally available resource (e.g., a local water source). Further,
or instead, the reaction carried out in the chamber 130 of the
reactor 128 may include one or more byproducts that, in the
proportions generated in the chamber 130, may not necessarily be
useful for introduction into the volume 108. Accordingly, if may be
useful to remove at least a portion of such byproducts from the
flow moving along the exhaust 138, toward the volume 108 of the
aircraft 102.
[0056] As an example, the delivery system 104 may include a swirl
separator 140 to separate one or more light components from one or
more heavier gaseous components (e.g., components formed from
impurities in the fluid source 136) in the flow from the outlet
region 134 of the reactor 128 and direct the hydrogen from the
swirl separator 140 toward the volume of the inflatable structure.
The swirl separator 140 may be, for example, disposed along the
exhaust 138, between the outlet region 134 of the reactor 128 and
the drain valve 110 of the aircraft 102. The flow from the outlet
region 134 may move into the swirl separator 140, where swirl is
imparted to the flow. Returning again to the example of forming
hydrogen by exposing activated aluminum to water, the radial forces
imparted on the flow moving through the swirl separator 140 may be
effective in separating hydrogen and steam from heavier liquid
components (e.g., condensed water) to form the lifting gas 109.
That is, continuing with this example, the lifting gas 109 exiting
the swirl separator 140 may have a higher volumetric concentration
of hydrogen and steam than the volumetric concentration of hydrogen
and steam in the flow moving into the swirl separator 140. That is,
by separating liquid components from gaseous components, the swirl
separator 140 may increase the lift capacity of the lifting gas 109
moving through the swirl separator 140. As a specific example, the
swirl separator 140 may be a swirl vane separator and, thus, may
increase lift capacity of the flow moving through the swirl
separator 140 without the use of external power or moving parts,
with such features being useful for robust performance in
generating the lifting gas 109 the field.
[0057] In certain implementations, the aircraft system 100 may
include a controller 142 having a processing unit 144 and a
computer-readable storage medium 146 having stored thereon
instructions for causing the processing unit 144 to carry out one
or more aspects of any of the various different techniques
described herein for forming the lifting gas 109 and delivering the
lifting gas 109 into the volume 108 of the aircraft 102. In certain
implementations, all or a portion of the controller 142 may be
decoupled from the aircraft 102 once the inflatable structure 106
has been sufficiently inflated for flight. In some implementations,
however, all or a portion of the controller 142 may remain coupled
to the aircraft 102 during flight such that the controller 142 is
part of the payload carried by the aircraft 102 and the computing
facility of the controller 142 may be used to monitor changing
conditions of the lifting gas 109 in the volume 108 and/or to
provide computing capacity for observations carried out by the
aircraft 102 during flight.
[0058] In some implementations, the controller 142 may operate
based on feedback from one or more signals related to conditions in
the volume 108 as the lifting gas 109 is moved into the volume 108
via the drain valve 110 or another orifice in fluid communication
with the volume 108 and the delivery system 104. For example, the
controller 142 may include a pressure sensor 148 in electrical
communication with the processing unit 144 and disposed relative to
the volume 108 to sense pressure in the volume 108. Additionally,
or alternatively, the controller 142 may include a temperature
sensor 150 in electrical communication with the processing unit 144
and disposed relative to the volume 108 to sense temperature in the
volume 108. Thus, as described in greater detail below, the
pressure sensor 148 and the temperature sensor 150 may be used to
determine a density in the volume 108 and, thus, provide an
indication of lift capacity of the lifting gas 109 in the volume
108 as the lifting gas 109 is received into the volume 108 during
inflation. Still further, or instead, the controller 142 may
include a motion sensor 151 in electrical communication with the
processing unit 144 and coupled to the aircraft 102 (e.g., coupled
in proximity to the drain valve 110) to detect motion of the
aircraft 102 indicative of flight. For example, in instances in
which the controller 142 is carried with the aircraft 102 during
flight, the signal from the motion sensor 151 may provide an
indication to the controller 142 that the aircraft 102 is no longer
being prepared for flight and the controller 142 may control the
drain valve 110 to expel water from the volume 108 in instances in
which the drain valve 110 includes one or more electronic
components, such as an electronically actuated valve by itself or
in combination with the float valve 112. As described in greater
detail below, controlling the drain valve 110 based on the motion
sensor 151 may be useful for providing an appropriate amount of
ballast to the aircraft 102 to facilitate achieving stable
flight.
[0059] In certain implementations, the controller 142 may include a
user interface 152 to receive one or more inputs from an operator.
The user interface 152 may be any one or more of various different
types of user interfaces, examples of which include, but are not
limited to a keyboard, a mouse, a touchscreen, voice command, etc.
In certain implementations, the user interface 152 may receive
information related to the intended mission of the aircraft 102.
Such information may include, for example, target altitude for the
aircraft 102.
[0060] FIG. 2 is a flowchart of an exemplary method 200 of
controlling lift of an aircraft propelled upward by low density
(buoyancy) relative to air and volume of a lifting gas. Unless
otherwise specified or made clear from the context, the exemplary
method 200 may be implemented using any one or more of the various
different systems, and components thereof, described herein. Thus,
for example, the exemplary method 200 may be implemented as
computer-readable instructions stored on the computer-readable
storage medium 146 (FIG. 1A) and executable by the processing unit
144 (FIG. 1A) of the controller 142 (FIG. 1A) to operate the
delivery system 104 and/or the aircraft 102 of aircraft system 100
(FIG. 1A).
[0061] As shown in step 202, the exemplary method 200 may include
receiving input related to one or more flight parameters of the
aircraft. The aircraft may be, for example, any one or more of the
various different aircraft described herein as including an
inflatable structure defining a volume. The input may be, for
example, provided an operator through a user interface (e.g., the
user interface 152 of the controller 142 in FIG. 1A). Additionally,
or alternatively, the input including the target altitude for the
aircraft may be received in a communication from a remote location
through wired and/or wireless communication with a controller, such
as the controller 142 (FIG. 1A).
[0062] The input related to the one or more flight parameters of
the aircraft may include, for example, a target altitude for the
aircraft. In aircraft propelled at least partially by buoyancy, the
target altitude may be particularly useful for facilitating
achievement of mission goals of the aircraft, particularly during
unmanned flight. For example, the target altitude may represent an
approximation of a maximum altitude to be achieved by the aircraft
to provide useful observations. Further, or instead, the target
altitude may represent a minimum altitude for providing useful
observations. In certain instances, the input related to the one or
more flight parameters of the aircraft may include information
about known environmental conditions (e.g., temperature and/or
altitude above sea level) at the launch site and/or along one or
more points along an expected flight path of the aircraft (e.g.,
environmental conditions at the target altitude). Such parameters
regarding environmental conditions may, for example, facilitate
more accurate determinations of the flight path of the aircraft, as
compared to determinations made without information about
environmental conditions. Similarly, to facilitate accurate
determinations of the flight path of the aircraft, the input
related to the one or more flight parameters may include one or
more parameters related to weight of the aircraft, including any
payload (e.g., instrumentation and/or supplies) carried by the
aircraft. Thus, more generally, the input related to the one or
more flight parameters may be any one or more of various different
conditions useful for determining initial parameters of the lifting
gas in the volume of an aircraft to facilitate lifting the aircraft
along an approximate flight path associated with a particular
mission of the aircraft.
[0063] As shown in step 204, the exemplary method 200 may include
determining a target density of a lifting gas in the volume
according to a model stored on the one or more non-transitory
computer storage media. The model may be any one or more of various
different empirical, semi-empirical, or non-empirical models
suitable for calculating the target density of the lifting gas
that, based on the model, is expected to result in lifting the
aircraft to the target altitude. By way of example, and not
limitation, the model may be based on the buoyancy equation (Eq. 1)
described above and solving (e.g., numerically) for an initial
density of the lifting gas at time=0. Additionally, or
alternatively, the model may be based on data from actual flight
parameters of the same or like aircraft using the same or similar
lifting gas. In certain instances, the model may indicate how much
of one or more reactants are required to generate a required amount
of lifting gas. In some instances, the model may also, or instead,
determine the maximum load that can be carried by the lifting gas
such that the aircraft will continue rising through the atmosphere
even as the aircraft loses buoyancy due to formation of condensate
in a volume defined by an inflatable structure of the aircraft.
[0064] As an example, returning again to the example of forming
hydrogen and steam through reaction of activated aluminum and
water, the model may indicate a minimum amount of activated
aluminum and water needed to produce a sufficient amount of lifting
gas need to achieve the target density and, thus, the required
amount of lift needed for the aircraft. The indication of the
minimum amount of activated aluminum may be based on theoretical
and/or experimental determinations of yield of hydrogen and steam
formed from a given amount of activated aluminum exposed to water.
Importantly, because the devices and systems described herein are
robust with respect to the presence of steam and/or condensed water
and provide control over lift capacity of lifting gas in the volume
of an aircraft, it shall be generally understood that an indication
of only a minimum amount of each reactant may be generally
sufficient for generating the lifting gas at the launch site. In
some use cases, this may be significant in facilitating rapid
deployment of the aircraft and/or facilitating deployment of the
aircraft by personnel without specialized training.
[0065] As shown in step 206, the exemplary method 200 may include
receiving a first signal indicative of temperature of the lifting
gas in the volume. The first signal may be received, for example,
from a temperature sensor (e.g., one or more thermocouples)
disposed relative to the volume at a position suitable for
providing an accurate indication of the temperature of the lifting
gas in the volume. In certain instances, the temperature sensor may
be disposed outside of the volume (e.g., in the vicinity of an
inlet to the volume, such as at the drain valve), as may be useful
for disconnecting the temperature sensor from the aircraft prior to
flight. Additionally, or alternatively, the temperature sensor may
be disposed inside of the volume, as may be useful for providing
accurate indications of temperature as the aircraft is being
prepared for flight and/or during flight.
[0066] As shown in step 208, the exemplary method 200 may include
receiving, from a pressure sensor, a second signal indicative of
pressure of the lifting gas in the volume. The pressure sensor may
be disposed, for example, in the volume. Further, or instead, the
pressure sensor may remain in the volume during flight of the
aircraft, such as may be useful for providing feedback to a
controller regarding the lifting gas in the volume during flight of
the aircraft.
[0067] As shown in step 210, the exemplary method 200 may include
controlling a flow of the lifting gas into the volume from a source
in fluid communication with the volume. For example, the flow of
the lifting gas into the volume may be based on the first signal
indicative of temperature, the second signal indicative of
pressure, and the target density. That is, the first signal and the
second signal may be used to determine density of the lifting gas
in the volume. In some cases, the determination of density of the
lifting gas in the volume may be based on any one or more of
various different approximations of composition of the lifting gas
in the volume. Examples of such approximations include, but are not
limited to the following: assuming the lifting gas is the heaviest
gaseous product of a reaction used to produce the lifting gas,
assuming the lifting gas is the lightest gaseous product of a
reaction used to produce the lifting gas, or assuming the lifting
gas has a composition in the volume corresponding to a theoretical
composition of products formed from the reaction carried out in the
reactor. An additional, or alternative, approach to measuring
buoyancy of the lifting gas may include measuring the lifting force
of the aircraft before takeoff via a force sensor or load cell.
Once the target density of the lifting gas has been achieved, flow
of the lifting gas into the volume may be interrupted by sending a
signal to close a valve (e.g., the drain valve 110 and/or any one
or more of various different valves disposed along the exhaust 138
in FIG. 1A).
[0068] As shown in step 212, the exemplary method 200 may include
receiving, from a motion sensor, a third signal indicative of
movement of the inflatable structure. That is, the motion sensor
may provide an indication of whether the aircraft is being prepared
for flight or is in flight. In general, delineation between these
two states may be useful for carrying out specific controls
particular to each state. For example, in instances in which the
motion sensor indicates that the aircraft is still such that it is
being prepared for flight, a controller may carry out one or more
control functions associated with providing a lifting gas to a
volume of the aircraft. Additionally, or alternatively, in
instances in which the motion sensor indicates that the aircraft is
moving such that it is in flight, the controller may carry out one
or more control functions associated with achieving efficient
flight. As a specific example, based on the third signal provided
by the motion sensor, actuation of a drain valve in fluid
communication with the volume of the inflatable structure may be
selectively controlled such that moisture condensed in the volume
is selectively released from the inflatable structure to ballast
the inflatable structure. That is, as the third signal indicates a
larger amount of motion, the drain valve may remain closed to
retain more moisture in the volume to provide more ballast to the
aircraft (e.g., to provide stabilization that may be useful for
carrying out certain observations, such as photographic
observations). As the third signal indicates a smaller amount of
motion, the drain valve may be opened to retain less moisture in
the volume and, thus, reduce the amount of dead weight carried by
the aircraft. Thus, in general, the third signal from the motion
sensor may be useful for achieving a balance between competing
considerations related to stable flight and achieving the target
altitude.
[0069] Having described various aspects of aircraft systems
including delivery systems that produce lifting gas for providing
lift to aircraft, attention is now turned to other techniques that
may be used in preparing a lifting gas for providing lift to
aircraft. The techniques described below are described separately
from each other and separately from the techniques described above
for the sake of clear and efficient explanation. Thus, unless
otherwise specified, or made clear from the context, it shall be
understood that any one or more of the various different techniques
described below may be used in addition to, or instead of, the
various different techniques described above.
[0070] Referring now to FIG. 3, an aircraft system 300 may include
an aircraft 302 and a delivery system 304. For the sake of clear
and efficient description, elements of the aircraft system 300
should be understood to be analogous to or interchangeable with
elements of the aircraft system 100 corresponding to 100-series
element numbers (e.g., in FIGS. 1A-1D) described herein, unless
otherwise explicitly made clear from the context and, therefore,
are not described separately from counterpart 100-series element
numbers, except to note differences and/or to emphasize certain
features. Thus, for example, the aircraft 302 of the aircraft
system 300 shall be understood to be identical the aircraft 102
(FIGS. 1A-1D), except to any extent indicated.
[0071] The delivery system 304 may include an exhaust 338, a
condenser 354, and a container 356. The exhaust 338 may extend from
an outlet region 334 of a reactor 328 to the aircraft 302 such that
the aircraft 302 and the chamber 330 of the reactor 328 may be in
fluid communication as the aircraft 302 is filled with a lifting
gas 309. For example, in instances in which hydrogen is formed from
reacting aluminum and water, the exhaust 338 may pass through the
condenser 354, where moisture in the flow entering the condenser
354 may condense into the container 356 in fluid communication with
the condenser 354 to decrease the density of the lifting gas 309.
By condensing at least a fraction of the steam in the condenser
354, the volumetric concentration of hydrogen in the lifting gas
309 is increased, thus increasing the lift capacity of the lifting
gas 309. Steam and any reaction byproduct that travels with the
hydrogen into the aircraft 302 may later condense to form a
condensate releasable from the aircraft 302 according to any one or
more of the various different techniques described herein.
[0072] In some implementations, the condensate condensed in the
condenser 354 and collected in the container 356 is also one of the
reactants used in the reaction taking place in the chamber 330, the
container 356 may be in fluid communication with a fluid source 336
(e.g., the condensate from the condenser 354 may empty into the
fluid source 336 such that the fluid source 336 is also the
container 356). As may be appreciated, such recirculation of the
condensate may advantageously result in more efficient use of the
reactant being delivered from the fluid source 136 into chamber 330
for reaction to produce the lifting gas 309 and/or a precursor to
the lifting gas 309. In turn, this may reduce the overall size
required for the fluid source 336.
[0073] In certain implementations, the delivery system 304 may
include a first heat exchanger 358 in thermal communication with
the condenser 354 to facilitate forming the fluid collected in the
container 356. The first heat exchanger 358 may be, for example, in
thermal communication between the condenser 354 and the fluid
source 336 such that the fluid source 336 provides cooling useful
for condensing the fluid out of the flow moving through the
condenser 354. Additionally, or alternatively, the first heat
exchanger 358 may include a separate cooling fluid (e.g., a
refrigerant), such as may be useful for launching the aircraft 302
in hot environmental conditions (e.g., such as those encountered in
the environment).
[0074] Additionally, or alternatively, the delivery system 304 may
include a second heat exchanger 360 in thermal communication with
the chamber 330 of the reactor 328, as may be particularly useful
in instances in which the reaction carried out in the chamber 330
is exothermic (e.g., the formation of hydrogen through reaction of
aluminum and water). For example, the second heat exchanger 360 may
facilitate further heating the lifting gas 309, moving through the
exhaust 338, just prior to introducing the lifting gas 309 into the
aircraft 302. In particular, to the extent condensation of the
fluid at the condenser 354 removes heat from the flow moving
through the condenser 354, at least some of the removed heat may be
reintroduced into the lifting gas 309 via the second heat exchanger
360. Such additional heat reduces the density of the lifting gas
309--thus, increasing the lift capacity of the lifting gas 309.
Thus, in general, it shall be appreciated that the first heat
exchanger 358 (to condense some water or other components from the
lifting gas 309 to decrease density of the lifting gas 309 prior to
delivery into the aircraft 302) and the second heat exchanger 360
(to add heat to the lifting gas 309 prior to delivery of the
lifting gas 309 into the aircraft 302, given that the higher
temperature of the lifting gas 309 results in lower density and,
thus, greater buoyancy in air) may each contribute to increasing
lift capacity of the lifting gas 309 and, when used in combination
with one another, the resulting increase in lift capacity of the
lifting gas 309 may be greater than otherwise achievable with each
heat exchanger individually. That is, returning again to the
example of reacting aluminum and water to produce hydrogen, the
first heat exchanger 358 may condense some water from the lifting
gas 309 to decrease density of the lifting gas 309 and, the lifting
gas 309 with the lower water content, may then be heated by the
second heat exchanger 360 to decrease further the density of the
lifting gas 309 with lower water content before the lifting gas 309
is delivered to the aircraft 302.
[0075] Referring now to FIG. 4, an aircraft system 400 may include
an aircraft 402 and a delivery system 404. For the sake of clear
and efficient description, elements of the aircraft system 400
shall be understood to be analogous to or interchangeable with
elements of the aircraft system 100 corresponding to 100-series
element numbers (e.g., in FIGS. 1A-1D) and/or elements of the
aircraft system 300 corresponding to 300-series element numbers
(e.g., in FIG. 3), unless otherwise explicitly made clear from the
context and, therefore, are not described separately from
counterpart 100-series element numbers or 300-series element
numbers, as the case may be, except to note differences and/or to
emphasize certain features. Thus, for example, the aircraft 402 of
the aircraft system 400 shall be understood to be identical to the
aircraft 102 (FIGS. 1A-1D), except to any extent indicated.
Additionally, or alternatively, the delivery system 404 may include
a condenser 454 and a container 456 which shall be understood to be
identical to the condenser 354 (FIG. 3) and the container 356 (FIG.
3), respectively.
[0076] The delivery system 404 may include an auxiliary gas source
462 in fluid communication with the aircraft 402 (e.g., in fluid
communication with a volume of an inflatable structure of the
aircraft 402). In use, the auxiliary gas source 462 may be
actuatable to mix an auxiliary gas 464 from the auxiliary gas
source 462 with a lifting gas 409 moving in an exhaust 438 from an
outlet region 434 of the reactor 428 toward the aircraft 402, where
a mixture may be received into a volume of the aircraft 402 (e.g.,
as described above with respect to the volume 108 of the aircraft
102 in relation to FIGS. 1A-1D). In certain instances, the
auxiliary gas source 462 may be a pressurized gas bottle, which may
be advantageous for delivery the auxiliary gas 464 with a tightly
controlled composition.
[0077] In general, the auxiliary gas 464 may be any one or more of
various different gas compositions useful for improving safety
and/or lift capacity of the lifting gas 409. Accordingly, by way of
example, and not limitation, in instances in which water is removed
from the lifting gas 409 moving through the condenser 454, the
auxiliary gas 464 may be a gas having a lower density than water.
As shall be appreciated, the net result of processing the lifting
gas 409 in this way may be that the lift capacity of the lifting
gas 409 is increased relative to the lift capacity of the flow
initially entering the exhaust 438 from the outlet region 434 of
the reactor 428. Additionally, or alternatively, the auxiliary gas
464 may be relatively inert relative to the lifting gas 409 such
that the mixture of the auxiliary gas 464 and the lifting gas 409
is less combustible than the lifting gas 409 alone. As a specific
example of each of these advantages, the auxiliary gas 464 may be
helium--an inert gas that has a lower density than steam. While
helium is a non-renewable resource that may present certain
challenges with respect to storage and transport, the use of helium
as the auxiliary gas 464 may result in use of much less helium than
would be otherwise required to lift the aircraft 402 using helium
alone. As compared to larger quantities of helium, these smaller
quantities of helium may be more easily deployable in the
field.
[0078] The flow rate of the auxiliary gas 464 relative to the flow
rate of the lifting gas 409 may change the lift capacity and/or the
combustibility of the resulting mixture. Accordingly, in certain
instances, the delivery system 404 may include a valve 466
adjustable to control a ratio of the auxiliary gas 464 to the
lifting gas 409 ultimately delivered to the aircraft 402. For
example, the valve 466 may be manually adjustable to increase or
decrease the flow of the auxiliary gas 464. As another example, the
valve 466 may be electronically adjustable based on one or more
parameters (e.g., pressure and temperature) in the volume of the
aircraft 402 and/or based on a quantity of fluid condensed out of
the lifting gas 409.
[0079] Referring now to FIGS. 5A and 5B, an aircraft system 500 may
include an aircraft 502 and a delivery system 504. For the sake of
clear and efficient description, elements of the aircraft system
500 shall be understood to be analogous to or interchangeable with
elements of the aircraft system 100 corresponding to 100-series
element numbers (e.g., in FIGS. 1A-1D), elements of the aircraft
system 300 corresponding to 300-series element numbers (e.g., in
FIG. 3), and/or elements of the aircraft system 400 corresponding
to 400-series element numbers (e.g., in FIG. 4), unless otherwise
explicitly made clear from the context and, therefore, are not
described separately from counterpart 100-series element numbers,
300-series element numbers, or 400-series element numbers, as the
case may be, except to note differences and/or to emphasize certain
features. Thus, for example, the aircraft 502 of the aircraft
system 500 shall be understood to be identical to the aircraft 102
(FIGS. 1A-1D), except to any extent indicated.
[0080] The delivery system 504 may include a reactor 528 having a
housing 529 and a liner 531 disposed in the housing 529 such that
the liner 531 of the reactor 528 defines the chamber 530. In
certain implementations, the liner 531 may be removable from the
housing 529, such as may be useful for efficiently replacing a
reactant 533 (e.g., aluminum) used as component in a reaction to
form a lifting gas 509 and/or for recovering one or more reaction
byproducts (e.g., gallium and/or indium in instances in which
aluminum is treated with one or both of these materials) once the
reactant 533 has been reacted with a fluid 535 from a fluid source
536 to form the lifting gas 509. For example, one or both of the
inlet region 532 and the outlet region 534 may be disposed along
the housing 529 such that the liner 531 may be separable from the
housing 529 with little or no need to connect or disconnect
components of the delivery system 504 from the reactor 528 as the
liner 531 is placed into or removed from the housing 529. As a
specific example, the housing 529 may include door 537 that may be
opened to provide access to the liner 531 for removal from or
placement into the housing 529 (e.g., while one or both of the
inlet region 532 or the outlet region 534 remain connected to the
housing 529). With the liner 531 disposed in the housing 529, the
door 537 may be securely closed to facilitate insulating the liner
531 and/or providing a measure of safety to personnel in the
vicinity of the reactor 528 while a reaction is taking place in the
chamber 530. While the door 537 is shown as being along a side of
the housing 529, it shall be appreciated that the door 537 may
positioned anywhere along the housing 529 as may be suitable for
facilitating access to the liner 531. Further, or instead, in some
instances, the liner 531 may be flexible such that the liner 531
may be partially compressed to fit into and/or out of the door 537,
such as may be useful for forming the reactor 528 within a
particular size envelope.
[0081] In general, the liner 531 may be formed of any one or more
of various different types of material suitable for withstanding
conditions associated with the reaction in the chamber 530 without
significantly reacting or otherwise degrading. Thus, in some cases,
the liner 531 may be formed of one or more materials having stable
properties over a wide range of conditions in the field.
Additionally, or alternatively, the liner 531 may be formed of one
or more materials that may be formed with a flexible form factor
(e.g., in the form of a bag) such that multiple instances of the
liner 531 may be efficiently carried and/or stored when not in use.
Accordingly, as an example, the liner 531 may be formed of one or
more polymers (e.g., rubber), which are light, stable over a wide
range of conditions, and, in those instances in which it would be
useful, may be formed with a flexible form factor.
[0082] While the liner 531 may be used within the housing 529, it
shall be appreciated that the liner 531 may be used by itself in
some instances. That is, for some applications (e.g., those in
remote environments), the liner 531 may be used by itself without
the housing 529, such as may be useful for reducing the overall
weight of the aircraft system 500.
[0083] Referring now to FIG. 5B, the liner 531 may be attachable to
the aircraft 502 by one or more tethers 539 connectable, for
example, to an inflatable structure 506 of the aircraft 502. For
example, when the reaction in the liner 531 is sufficiently
completed to fill the inflatable structure 506 to sufficient
buoyancy, the liner 531 may be attached to the aircraft 502 using
the one or more tethers 539 such that the liner 531 and the
reaction byproducts therein may be carried away from the launch
site, as may be useful for removing traces of the launch site while
reducing the amount of material that must be carried away by
personnel at the launch site. As may be appreciated, the weight of
the liner 531 and its contents may provide ballast to the aircraft
502. In certain instances, the aircraft 502 may jettison the liner
531 at some point during flight, as may be useful for disposing of
the liner 531 and its contents away from the launch site without
carrying the weight of the liner 531 and its contents throughout
the entire flight.
[0084] While the liner 531 is shown as being attached to the
aircraft 502 using tethers 539, it shall be appreciated that one or
more other approaches to attaching the liner 531 to the aircraft
502 may additionally, or alternatively, be possible. For example,
the liner 531 may be attached to the aircraft 502 using all or a
portion of an exhaust 538 of the delivery system 504 such that the
liner 531 and all or a portion of the exhaust 538 are carried away
with the aircraft 502. This may be particularly useful, for
example, in instances in which the liner 531 is used without the
housing 529. Further, or instead, while a single instance of the
liner 531 is shown as being attached to the aircraft 502 to be
taken away, it shall be appreciated that a plurality of instances
of the liner 531 may be attached to the aircraft 502 in some
cases.
[0085] While certain implementations have been described, other
implementations are additionally or alternatively possible.
[0086] For example, while lifting gas has been described as being
at least partially generated through a reaction carried out in a
reactor, additional or alternative approaches to delivering a
lifting are possible. As an example, referring now to FIG. 6, an
aircraft system 600 may include an aircraft 602 and a delivery
system 604. For the sake of clear and efficient description,
elements of the aircraft system 600 shall be understood to be
analogous to or interchangeable with elements of the aircraft
system 100 corresponding to 100-series element numbers (e.g., in
FIGS. 1A-1D), elements of the aircraft system 300 corresponding to
300-series element numbers (e.g., in FIG. 3), and/or elements of
the aircraft system 400 corresponding to 400-series element numbers
(e.g., in FIG. 4), unless otherwise explicitly made clear from the
context and, therefore, are not described separately from
counterpart 100-series element numbers, 300-series element numbers,
or 400-series element numbers, as the case may be, except to note
differences and/or to emphasize certain features. Thus, for
example, the aircraft 602 of the aircraft system 600 shall be
understood to be identical to the aircraft 102 (FIGS. 1A-1D),
except to any extent indicated.
[0087] The delivery system 604 may include an exhaust 638, a
compressed gas cylinder 668, and a heater 670 (e.g., an electric
heater powered by a separate power source). The compressed gas
cylinder 668 may include a lifting gas 609 having, for example, a
known composition. Pressure in the compressed gas cylinder 668 may
move the lifting gas 609 along the exhaust 638, in a direction
toward the aircraft 602. The heater 670 may be in thermal
communication with the exhaust 638, between the compressed gas
cylinder 668 and the aircraft 602 to heat the lifting gas 609 as it
moves past the heater 670. That is, as the lifting gas 609 moves
past the heater 670 the lift capacity of the lifting gas 609 may
increase. In certain implementations, the temperature of the
lifting gas 609 may be tightly controlled such that, in combination
with the known composition of the lifting gas 609 in the compressed
gas cylinder 668, the lift capacity of the lifting gas 609 in the
aircraft 602 may be known more accurately, as compared to
techniques in which the temperature and/or composition of a lifting
gas are not tightly controlled or are not controlled at all. Such
precise knowledge of the lift capacity of the lifting as 509 may be
useful, for example, in achieving precision in the flight path
executed by the aircraft 602.
[0088] As another example, while the use of lifting gas has been
described with respect to providing lift to aircraft described
herein, other uses of the lifting gas onboard of the aircraft are
additionally or alternatively possible. For example, referring now
to FIG. 7, an aircraft 702 may include an inflatable structure 706,
a nozzle 772, an igniter 774, and a payload 776. For the sake of
clear and efficient description, elements of the aircraft 702 shall
be understood to be analogous to or interchangeable with elements
of the aircraft 102 corresponding to 100-series element numbers
(e.g., in FIGS. 1A-1D), elements of the aircraft 302 corresponding
to 300-series element numbers (e.g., in FIG. 3), elements of the
aircraft 402 corresponding to 400-series element numbers (e.g., in
FIG. 4), and/or elements of the aircraft 602 corresponding to
500-series element numbers, unless otherwise explicitly made clear
from the context and, therefore, are not described separately from
counterpart 100-series element numbers, 300-series element numbers,
400-series element numbers, or 500-series element numbers, as the
case may be, except to note differences and/or to emphasize certain
features. Thus, for example, the aircraft 702 of the aircraft
system 400 shall be understood to be identical to the aircraft 102
(FIGS. 1A-1D), except to any extent indicated. In particular,
unless otherwise specified or made clear from the context, the
inflatable structure 706 of the aircraft 702 shall be understood to
define a volume analogous to the volume 108 defined by the
inflatable structure 106 in FIGS. 1A-1D and, thus, while this
volume is not described separately, it shall be understood to
contain a lifting gas providing buoyancy to the aircraft 702 during
flight.
[0089] In general, the nozzle 772 may be selectively actuatable in
fluid communication with the volume defined by the inflatable
structure 706 of the aircraft 702. The nozzle 772 may define an
exit 778 such that lifting gas in the volume defined by the
inflatable structure 706 may be delivered to the nozzle 772 and,
via the exit 778 of the nozzle 772, directed toward the payload
776. To the extent the lifting gas carried in the volume defined by
inflatable structure 706 is combustible (e.g., contains hydrogen or
a mixture thereof) when mixed with ambient air or by itself, the
lifting gas directed from the nozzle 772 toward the payload 776 may
be ignited to destroy the payload 776. This may be useful, for
example, for protecting sensitive information (e.g., proprietary
instrumentation) from being discovered (e.g., by hostile entities)
once the aircraft 702 descends to the ground upon completion of the
mission. Thus, more generally, the ability to destroy the payload
776 using a lifting gas carried on the aircraft 702 may facilitate
protecting sensitive technology and/or data without adding
significantly to the overall weight of the aircraft 702 and, thus,
without significantly impacting flight performance of the aircraft
702 under otherwise identical conditions.
[0090] In certain implementations, the nozzle 772 may include
control valve 780 (e.g., a normally closed solenoid valve)
positioned away from the exit 778, with the control valve 780 in
electrical communication with the payload 776. In use, the payload
776 may send a signal to actuate the control valve 780 such that
the nozzle 772 is selectively actuatable in fluid communication
with lifting gas in the volume defined by the inflatable structure
706 through actuation of the control valve 780. That is, to the
extent pressure of the lifting gas in the volume defined by the
inflatable structure 706 exceeds atmospheric pressure outside of
the inflatable structure 706, actuation of the control valve 780 in
response to the signal from the payload 776 may allow some of the
lifting gas to move from the volume into the nozzle 772, in a
direction generally toward the exit 778 of the nozzle 772.
[0091] In certain implementations, the nozzle 772 may be coupled to
any portion of the aircraft 702 suitable for orienting the exit 778
of the nozzle 772 toward the payload 776 while also being
positioned such that the exit 778 is close to the payload 776 such
that a flame extending from the exit 778 may reach the payload 776
as intended. For example, at least a portion of the payload 776 may
be exposed to an environment outside of the volume defined by the
inflatable structure 706 of the aircraft 702 such that the payload
776 may be ignited away from the volume containing the lifting gas.
That is, with at least a portion of the payload 776 exposed to the
environment outside of the volume, the aircraft 702 may be
destroyed in stages--with the payload 776 igniting and burning for
a period before the lifting gas in the volume is ignited. Such
staged burning may be useful for increasing the likelihood of
destroying the payload 776 before the aircraft 702 reaches the
ground.
[0092] Given the conditions likely to be encountered by the
aircraft 702 at altitude, the nozzle 772 may include a mixing
section 782 between the control valve 780 and the exit 778 of the
nozzle 772 and in fluid communication with at least the exit 778 of
the nozzle 772. The mixing section 782 may define, for example, at
least one orifice 784 through which air in the environment is
movable into the mixing section 782 to mix with the lifting gas
from the volume upon actuation of the control valve 780. The total
open area of the at least one orifice 784 may be sized to achieve
fuel/air ratios within the rich and lean ignition limits of the
expected composition of the lifting gas in the volume and the
oxygen concentration of air at a range of flight altitudes of the
aircraft 702.
[0093] The igniter 774 may be disposed in the vicinity of the exit
778 of the nozzle 772. As used in this context, the proximity of
the igniter 774 to the exit 778 of the nozzle 772 shall be
understood to include positions just beyond the exit 778 of the
nozzle 772 and, further or instead, may include positions within
the nozzle 772 such that the nozzle 772 may protect the igniter 774
from damage while also facilitating ignition of an ignitable
mixture in windy conditions that may be associated with flight of
the aircraft 702 at high altitude. Thus, in some instances, the
igniter 774 may be mechanically coupled to the nozzle 772. Further,
or instead, the igniter 774 may be in electrical communication with
the payload 776 such that one or more electrical signals generated
by the payload 776 may ignite the igniter 774 while the control
valve 780 of the nozzle 772 is open such that lifting gas is
flowing toward the exit 778 of the nozzle 772. For example, the
igniter 774 may be a spark ignitor, and the one or more electrical
signals generated by the payload 776 may generate a spark that
ignites an air/fuel mixture (e.g., an air/fuel mixture generated in
the mixing section 782) moving past the igniter 774.
[0094] In general, the payload 776 may include a strategic portion
741 and a controller 742. The strategic portion 741 of the payload
776 may include any one or more of various different types of
various different sensitive material collected by or otherwise
received by the aircraft 702 as part of a mission being carried out
by the aircraft 702 by itself or when deployed with multiple
instances of the aircraft 702. Unless otherwise specified or made
clear from the context, the controller 742 may be analogous to the
controller 142 (FIG. 1A) described above and, thus, is not
described separately except to note additional or alternative
features. Thus, for example, the controller 742 may include a
processing unit 744 and a computer-readable storage medium 746,
which shall be understood to be analogous to the processing unit
144 and the computer-readable storage medium 146, respectively,
described above with respect to FIG. 1A. In addition to, or as an
alternative to, other instructions stored in the computer-readable
storage medium 746 for controlling inflation and/or flight of the
aircraft 702, the computer-readable storage medium 746 may have
stored thereon instructions that, when executed by the processing
unit 744, cause the processing unit 744 to perform operations
including actuating the nozzle 772 (e.g., by sending an electrical
signal to the control valve 780 in electrical communication with
the payload 776) to issue the lifting gas from the exit 778 of the
nozzle 772 in a direction toward at least the strategic portion 741
of the payload 776. That is, given the sensitivity of the strategic
portion 741, the nozzle 772 may oriented toward the strategic
portion 741 of the payload 776 to increase the likelihood of
destroying the strategic portion 741 of the payload 776 using a
flame from the nozzle 772. In certain instances, as the strategic
portion 741 of the payload 776 is being destroyed, the controller
742 may continue to operate for a period, such as may be useful for
facilitating continued flight of the aircraft 702. That is, by
facilitating continued flight of the aircraft 702 as the strategic
portion 741 of the payload 776 is being destroyed, there may be a
reduced risk that destruction of the strategic portion 741 of the
payload 776 may be prematurely interrupted, thus frustrating the
corresponding attempt to destroy the strategic portion 741 of the
payload 776. In certain instances, the strategic portion 741 of the
payload 776 may be at least partially exposed to the environment
outside of the aircraft 702 to facilitate destroying the strategic
portion 741 of the payload 776 using a flame from the nozzle 772.
Further or instead, the controller 742 may be computer-readable
storage medium 746 may have stored, thereon instructions that, when
executed by the processing unit 744, cause the processing unit 744
to send a signal to the igniter 774 in electrical communication
with the payload 776 to ignite a combustible mixture including the
lifting gas directed from the exit 778 of the nozzle 772 toward the
payload 776 exposed to an environment outside of the volume, the
inflatable structure 706, or a combination thereof.
[0095] In some implementations, the aircraft 702 may further
include a sensor 786 in electrical communication with the
controller 742. Continuing with this example, the computer-readable
storage medium 746 of the controller 742 may further, or instead,
have stored thereon computer readable instructions that, when
executed by the processing unit 744, cause the processing unit 744
to receive a signal from the sensor 786 and to actuate at least one
of the nozzle 772 (e.g., the control valve 780) or the igniter 774
based on the signal from the sensor 786. For example, the sensor
786 may be an altimeter such that the controller 742 may ignite the
payload 776 based on any one or more of various conditions
associated with altitude of the aircraft 702 (e.g., when the
aircraft 702 descends to a predetermined altitude). Additionally,
or alternatively, the sensor 786 may include one or more of
thermocouple, a timer, or a global positioning system receiver.
Further, or instead, the sensor 786 may include a wireless
communication receiver such that the controller 742 may initiate
destruction of the payload 776 based on a signal received from a
remote source, such as an operator on the ground.
[0096] In some instances, the aircraft 702 may further include a
transmitter 788 in electrical communication with the controller
742. In such instances, the computer-readable storage medium 746 of
the controller 742 may further, or instead, have stored thereon
computer readable instructions that, when executed by the
processing unit 744, cause the processing unit 744 to activate the
transmitter 788 (e.g., based on the signal from the sensor 786) to
transmit data from the strategic portion 741 of the payload 776
prior to destruction of the strategic portion 741 of the payload
776. The transmitter 788 may be any one or more of various
different transmitters suitable for carrying out a particular type
of communication (e.g., encrypted communication). By way of
example, and not limitation, the transmitter 788 may be a line of
sight data transmitter. For example, the transmitter 788 may
transmit data from the strategic portion 741 of the payload 776 to
another instance of the aircraft 702 within line of sight of the
instance of the aircraft 702 being destroyed. As may be appreciated
from this example, a plurality of instances of the aircraft 702 may
communicate sensitive information in this way to increase the
likelihood that the sensitive information may be retrieved by an
intended party while decreasing the likelihood that the sensitive
information will be intercepted by an unintended party.
[0097] The above systems, devices, methods, processes, and the like
may be realized in hardware, software, or any combination of these
suitable for the control, data acquisition, and data processing
described herein. This includes realization in one or more
microprocessors, microcontrollers, embedded microcontrollers,
programmable digital signal processors or other programmable
devices or processing circuitry, along with internal and/or
external memory. This may also, or instead, include one or more
application specific integrated circuits, programmable gate arrays,
programmable array logic components, or any other device or devices
that may be configured to process electronic signals. It will
further be appreciated that a realization of the processes or
devices described above may include computer-executable code
created using a structured programming language such as C, an
object oriented programming language such as C++, or any other
high-level or low-level programming language (including assembly
languages, hardware description languages, and database programming
languages and technologies) that may be stored, compiled or
interpreted to run on one of the above devices, as well as
heterogeneous combinations of processors, processor architectures,
or combinations of different hardware and software. At the same
time, processing may be distributed across devices such as the
various systems described above, or all of the functionality may be
integrated into a dedicated, standalone device. All such
permutations and combinations are intended to fall within the scope
of the present disclosure.
[0098] Embodiments disclosed herein may include computer program
products comprising computer-executable code or computer-usable
code that, when executing on one or more computing devices,
performs any and/or all of the steps of the control systems
described above. The code may be stored in a non-transitory fashion
in a computer memory, which may be a memory from which the program
executes (such as random access memory associated with a
processor), or a storage device such as a disk drive, flash memory
or any other optical, electromagnetic, magnetic, infrared or other
device or combination of devices. In another aspect, any of the
control systems described above may be embodied in any suitable
transmission or propagation medium carrying computer-executable
code and/or any inputs or outputs from same.
[0099] The method steps of the implementations described herein are
intended to include any suitable method of causing such method
steps to be performed, consistent with the patentability of the
following claims, unless a different meaning is expressly provided
or otherwise clear from the context. So, for example performing the
step of X includes any suitable method for causing another party
such as a remote user, a remote processing resource (e.g., a server
or cloud computer) or a machine to perform the step of X.
Similarly, performing steps X, Y and Z may include any method of
directing or controlling any combination of such other individuals
or resources to perform steps X, Y and Z to obtain the benefit of
such steps. Thus, method steps of the implementations described
herein are intended to include any suitable method of causing one
or more other parties or entities to perform the steps, consistent
with the patentability of the following claims, unless a different
meaning is expressly provided or otherwise clear from the context.
Such parties or entities need not be under the direction or control
of any other party or entity, and need not be located within a
particular jurisdiction.
[0100] It will be appreciated that the methods and systems
described above are set forth by way of example and not of
limitation. Numerous variations, additions, omissions, and other
modifications will be apparent to one of ordinary skill in the art.
In addition, the order or presentation of method steps in the
description and drawings above is not intended to require this
order of performing the recited steps unless a particular order is
expressly required or otherwise clear from the context. Thus, while
particular embodiments have been shown and described, it will be
apparent to those skilled in the art that various changes and
modifications in form and details may be made therein without
departing from the scope of the disclosure.
* * * * *