U.S. patent application number 14/015796 was filed with the patent office on 2014-01-02 for transportation system and vehicle for supersonic transport.
This patent application is currently assigned to Supersonic Tubevehicle LLC. The applicant listed for this patent is Supersonic Tubevehicle LLC. Invention is credited to Arnold R. Miller.
Application Number | 20140000473 14/015796 |
Document ID | / |
Family ID | 49776803 |
Filed Date | 2014-01-02 |
United States Patent
Application |
20140000473 |
Kind Code |
A1 |
Miller; Arnold R. |
January 2, 2014 |
TRANSPORTATION SYSTEM AND VEHICLE FOR SUPERSONIC TRANSPORT
Abstract
A transportation system for supersonic travel including a
conduit containing an atmosphere that exhibits high aerodynamic
tunneling performance, or high gas efficacy, and a vehicle designed
to operate within the conduit. The vehicle traveling within the
conduit along a support and guide structure that is complementary
to a support and guidance system of the vehicle. The vehicle being
propelled through the conduit via a propulsion system that includes
contra-rotating propellers.
Inventors: |
Miller; Arnold R.;
(Lakewood, CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Supersonic Tubevehicle LLC |
Golden |
CO |
US |
|
|
Assignee: |
Supersonic Tubevehicle LLC
Golden
CO
|
Family ID: |
49776803 |
Appl. No.: |
14/015796 |
Filed: |
August 30, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12698887 |
Feb 2, 2010 |
8534197 |
|
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14015796 |
|
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|
61695983 |
Aug 31, 2012 |
|
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61840232 |
Jun 27, 2013 |
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Current U.S.
Class: |
104/138.1 ;
105/1.1 |
Current CPC
Class: |
H01M 8/0618 20130101;
B61C 11/06 20130101; B60L 2240/12 20130101; B60L 2220/14 20130101;
B60L 2200/26 20130101; H01M 8/04164 20130101; B61B 13/08 20130101;
B61B 13/10 20130101; B60L 58/30 20190201; H01M 2250/20 20130101;
B61C 17/06 20130101; B60L 58/40 20190201; H01M 8/04201 20130101;
Y02T 10/70 20130101; B60L 9/24 20130101; B61C 3/00 20130101; B61C
17/00 20130101; Y02T 90/40 20130101; B60L 9/28 20130101; Y02E 60/50
20130101; B61D 17/02 20130101; B60L 13/04 20130101 |
Class at
Publication: |
104/138.1 ;
105/1.1 |
International
Class: |
B61B 13/10 20060101
B61B013/10; B61D 17/02 20060101 B61D017/02 |
Claims
1. A tube vehicle comprising: a vehicle body having an outside
portion; at least one source of power supported by the vehicle
body; a motor operably coupled with the at least one source of
power and configured to receive power from the at least one source
of power; at least one propeller arrangement supported at a first
end of the outside portion of the vehicle body and operably coupled
with the motor, the at least one propeller arrangement providing
propulsion to the vehicle within an enclosed structure in which the
vehicle travels and configured to operate within an atmosphere of
the enclosed structure that allows the vehicle to achieve
aerodynamic tunneling.
2. The tube vehicle of claim 1 wherein the vehicle body is
substantially cylindrical and configured to fit within the
dimension of the enclosed structure and wherein the enclosed
structure is a tube.
3. The tube vehicle of claim 1 wherein the at least one source of
power includes at least one fuel-cell stack and wherein the vehicle
further includes an intake mechanism supported on the outside
portion of the vehicle body, the intake mechanism configured to
receive a gas from an atmosphere in which the vehicle is traveling,
the gas being a fuel source for the at least one fuel-cell
stack.
4. The tube vehicle of claim 3 wherein the gas is hydrogen and the
at least one fuel-cell stack is a proton-exchange membrane fuel
cell, the hydrogen being a fuel (reductant) source for at least one
fuel-cell stack.
5. The tube vehicle of claim 3 further comprising: an oxidant
storage tank, wherein the oxidant storage tank provides oxygen to
the at least one fuel cell stack.
6. The tube vehicle of claim 5 wherein the oxidant storage tank
holds liquid oxygen and further includes a water storage tank to
store water exhausted from the fuel cell during operation.
7. The tube vehicle of claim 3 further comprising: an exhaust,
wherein the exhaust is located on the outside portion of the
cylindrical body, the exhaust is connected to an exit of the fuel
cell and distributes a gas from the exit of the fuel to outside the
vehicle; and a separator disposed between the exit of the fuel cell
and the exhaust, wherein the separator separates gas and other
materials from the exit of the fuel.
8. The tube vehicle of claim 1 further comprising a levitation
system on the outside portion of the vehicle body configured to
levitate the vehicle.
9. The tube vehicle of claim 8 wherein the levitation system
comprises a magnetic levitation system along a bottom portion of
the outside portion of the vehicle body.
10. The tube vehicle of claim 8 wherein the levitation system
comprises an aerostatic gas bearings along a bottom portion of the
outside portion of the vehicle body, the aerostatic gas bearing
providing a low-friction layer on the outside portion of the
vehicle body for the vehicle to propel on top of the layer.
11. The vehicle of claim 1 further comprising a plurality of wheels
configured to support the vehicle body on a support and guide
structure of the enclosed structure.
12. The tube vehicle of claim 11 wherein: the support and guide
structure defines a rail; and wherein the plurality of wheels are
aligned along a longitudinal centerline of the vehicle and include
an opposing side flanges that laterally constrain the wheels on the
rail.
13. The tube vehicle of claim 11 wherein each of the plurality of
wheels includes an aerostatic bearing spindle and a bearing
housing, the aerostatic bearing spindle including a plurality of
orifices that provide gas flow to a gap between the aerostatic
bearing spindle and the bearing housing, wherein the gas flow
supports the wheel.
14. The tube vehicle of claim 11 further comprising at least one
aileron supported on the outside portion of the vehicle body, the
at least one aileron configured to balance the vehicle during
movement of the vehicle.
15. The tube vehicle of claim 1 wherein the at least one source of
power includes at least one rechargeable battery, an electrical
catenary, or an electrical bus running parallel to the centerline
of the enclosed structure.
16. The tube vehicle of claim 1 wherein the propulsion system
includes two tandem propellers, with a first propeller supported at
a first end of the vehicle body and a second propeller supported at
a second end of the vehicle body.
17. The tube vehicle of claim 16 wherein the two tandem propellers
are contra-rotating propellers, and wherein a number of blades
included in each of the contra-rotating propellers is optimized for
the atmosphere provided in the enclosed structure.
18. The tube vehicle of claim 1 wherein the atmosphere provided in
the enclosed structure comprises of H.sub.2, NH.sub.3, CH.sub.4,
He, C.sub.2H.sub.2, C.sub.2H.sub.6, C.sub.3H.sub.8, C.sub.2H.sub.4,
N.sub.2, CO.sub.2, N.sub.2O, O.sub.2, SF.sub.6, Ar, Ne,
halocarbons, or any mixture of these gases.
19. The tube vehicle of claim 11 further including a fairing, the
fairing designed to streamline the plurality of wheels, and to
reduce aerodynamic drag and support the wheel bearings.
20. A transportation system comprising: a substantially enclosed
conduit provided between a first geographic location and a second
geographic location, the enclosed conduit having a cross-section of
a fluted tube and being provided with an atmosphere that allows a
vehicle traveling within the enclosed conduit to achieve
aerodynamic tunneling.
21. The transportation system of claim 20 wherein the fluted tube
is formed from two or more tubes conjoined along their lengths, and
wherein the conjoined tubes share their collective cross-sectional
areas and thereby reduce aerodynamic drag.
22. The transportation system of claim 20 wherein the enclosed
conduit is configured to support bidirectional or parallel
traffic.
23. The transportation system of claim 20 wherein the enclosed
conduit further includes at least one guideway configured to
support and guide a vehicle traveling within the conduit.
24. The transportation system of claim 20 wherein the overall gas
efficacy of the atmosphere provided within the enclosed conduit is
higher than the gas efficacy of the air outside of the conduit.
25. The transportation system of claim 20 wherein the atmosphere
provided within the enclosed conduit is H.sub.2, NH.sub.3,
CH.sub.4, He, C.sub.2H.sub.2, C.sub.2H.sub.6, C.sub.3H.sub.8,
C.sub.2H.sub.4, N.sub.2, CO.sub.2, N.sub.2O, O.sub.2, SF.sub.6, Ar,
Ne, halocarbons, or any mixture of these gases.
26. The transportation system of claim 20 wherein the atmosphere
provided in the conduit comprises density stages, the density
stages including gases of decreasing densities along the length of
the enclosed conduit, in the direction of vehicle acceleration
wherein each density stage is separated from another density stage
by at least one movable partition that allows the vehicle to
traverse from one density stage to another density stage.
27. The transportation system of claim 26 further comprising gases
of increasing density in the direction of deceleration wherein each
density stage is separated from another density stage by at least
one movable partition that allows the vehicle to traverse from one
density stage to another density stage.
28. The transportation system of claim 20 wherein the atmosphere
provided in the conduit comprises density stages, the density
stages including gases of increasing density in the direction of
deceleration, wherein each density stage is separated from another
density stage by at least one movable partition that allows the
vehicle to traverse from one density stage to another density
stage.
29. The transportation system of claim 20 further including at
least one vehicle dimensioned to fit within the conduit, the
vehicle comprising a propulsion system and a system configured to
support and guide the vehicle within the enclosed conduit.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part and claims
priority to co-pending application Ser. No. 12/698,887 titled
"Supersonic Hydrogen Tube Vehicle" filed on Feb. 2, 2010, which is
hereby incorporated by reference herein. This application also
claims priority under 35 U.S.C. .sctn.119(e) to provisional patent
applications 61/695,983 titled "Tube Vehicle for Supersonic
Transport," filed Aug. 31, 2012, and 61/840,232 titled "Tube
Vehicle for Supersonic Transport with Wheels and Balancing System,"
filed Jun. 27, 2013, which are hereby incorporated by reference
herein.
BACKGROUND
[0002] There are many ways to transport both people and goods,
including airplanes, automobiles, and trains. The length of time
that a trip may take is often a determining factor for the type of
transportation that may be used, and there is a demand for shorter
travel times between destinations. In addition to travel time, many
consumers choose their method of transportation based on cost and
consumers will often choose one airline carrier over another based
on ticket price. The efficiency of a method of transportation plays
a big role on costs passed on to consumers. For instance, when the
price of aviation fuel increases, some airlines also increase the
cost of tickets. Additionally, consumers are more environmentally
conscious and are looking to alternative energy modes of
transportation when making their transportation decisions.
[0003] Business travelers are primarily concerned with speed, and
automobiles are not the first choice for long distance travel. Such
consumers really have only one travel option: flying. The speed of
commercial aircraft, however, is practically limited by the speed
of sound, because as an airplane speeds up and begins to approach
the speed of sound, it enters a speed region known as the transonic
region. When the airplane enters the transonic region, parts of the
airflow over the airplane's surface are subsonic and parts are
supersonic. Air is strongly compressible near the speed of sound
and the supersonic parts emanate shock waves that are approximately
normal to the surface of the airplane. The shock waves increase
drag (wave drag) and decrease lift. Thus, as the speed of the
aircraft varies as it accelerates through the transonic region,
movement of the waves on the surface causes buffeting. The wave
drag gives rise to a power peak at Mach 1 called the "sound
barrier." After the airplane passes through the transonic region,
the stability of the vehicle improves and the power requirement
drops temporarily below the power peak of the sound barrier.
Nonetheless, the power continues to rise with speed and, due to
wave drag, is much higher than at subsonic speeds. Indeed, the
power in the supersonic region rises at more than the third-power
of speed. The additional power requirements make supersonic
airplanes prohibitively expensive to build and operate, especially
for commercial use. This means that in order to increase their
speed past the speed of sound, aircraft must use significantly more
fuel, charge higher prices for either passengers or cargo in order
to make up for the increases in fuel usage, and will expel more
emissions into the environment.
[0004] The foregoing examples of the related art and limitations
therewith are intended to be illustrative and not exclusive. Other
limitations of the related art will become apparent to those of
skill in the art upon a reading of the specification and a study of
the drawings.
SUMMARY
[0005] Aspects of the present disclosure involve a transportation
system including a substantially enclosed conduit. The conduit is
provided between a first geographic location and a second
geographic location. The conduit has a cross-section of a fluted
tube and is provided with an atmosphere that allows a vehicle
traveling within the conduit to achieve aerodynamic tunneling.
[0006] Another aspect of the disclosure involves a vehicle
including at least one source of power and a motor operably coupled
with the at least one source of power and configured to receive
power from the at least one source of power. In one specific
example, the at least one source of power includes at least one
fuel-cell stack that uses a gas from an atmosphere included in the
enclosed structure in which the vehicle travels as a fuel source.
The vehicle includes a propulsion system supported on the outside
portion of the vehicle body and configured to move the vehicle
through the enclosed structure. The propulsion system being
operable coupled to the motor. The propulsion system, in one
implementation, includes at least one propeller supported at one
end of the vehicle. The propeller being configured to operate
within an atmosphere of the enclosed structure that allows the
vehicle to achieve aerodynamic tunneling.
[0007] The following embodiments and aspects thereof are described
and illustrated in conjunction with systems, tools, and methods
that are meant to be exemplary and illustrative, and the
embodiments and aspects described and illustrated are not intended
to be limiting in scope. In various embodiments, one or more of the
above-described problems have been reduced or eliminated, while
other embodiments are directed to other improvements. In addition
to the exemplary aspects and embodiments described above, further
aspects and embodiments will become apparent by reference to the
drawings and by study of the following descriptions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Exemplary embodiments are illustrated in referenced figures
of the drawings. It is intended that the embodiments and figures
disclosed herein are to be considered illustrative rather than
limiting. The use of the same reference numerals in different
drawings indicates similar or identical items.
[0009] FIG. 1 is a perspective view of a tube vehicle;
[0010] FIG. 2 is a perspective view of a different embodiment of a
tube vehicle;
[0011] FIG. 3 is a front perspective view of a segmented vehicle
including two vehicles connected with a car;
[0012] FIG. 4 is a perspective view of the tube vehicle of FIG. 1
within a tube;
[0013] FIG. 5 is a perspective view of the tube vehicle of FIG. 3
within a tube;
[0014] FIG. 6 is an isometric view of a portion of the tube with a
guideway for supporting the tube vehicle;
[0015] FIG. 7 is a schematic showing a magnetic-levitation
apparatus for the vehicle;
[0016] FIG. 8 is a schematic of one example of a tube with a fluted
tube configuration;
[0017] FIG. 9 is a schematic diagram of one example of "density
stages" within a tube;
[0018] FIG. 10 is a block diagram illustrating the functional
components of the vehicle of FIG. 2;
[0019] FIG. 11A is a side view of the vehicle of FIG. 10;
[0020] FIG. 11B is a bottom view of the vehicle of FIG. 10;
[0021] FIG. 12 is a perspective view of the inside of the tube
vehicle of FIG. 1 illustrating some of the functional components of
the vehicle;
[0022] FIG. 13 is a perspective view of a propeller system
according to some aspects of the disclosure;
[0023] FIGS. 14A and 14B are perspective views of a wheel and
bearing for the tube vehicle of FIG. 1 according to some aspects of
the disclosure;
[0024] FIG. 15 is a perspective view of a landing gear assembly for
the tube vehicle of FIG. 1 according to some aspects of the
disclosure; and
[0025] FIG. 16 is a perspective view of an aileron assembly for the
tube vehicle of FIG. 1 according to some aspects of the
disclosure.
DETAILED DESCRIPTION
[0026] Aspects of the present disclosure involve a vehicle capable
of supersonic travel (relative to air outside the conduit) that
"flies" in a substantially enclosed conduit provided with an
atmosphere that exhibits high aerodynamic (tunneling) performance,
such as a hydrogen atmosphere. The conduit is intended to be
enclosed and its interior isolated from air outside the conduit as
completely as is practicable, up to, for example, flaws in
manufacturing or fabrication (e.g., pinholes in welds). The conduit
may be of various configurations capable of supporting either
unidirectional or bidirectional transit. The vehicle includes one
or more fuel cells, rechargeable batteries, an electrical catenary,
an electrical bus running parallel to the centerline of the
conduit, or other sources of power that power the vehicle. In the
case of fuel cells, a gas within the conduit, such as hydrogen or
other gases can be used as a fuel source. The fuel cell,
rechargeable battery, or other source of power drives a propfan or
other propulsion system to propel the vehicle within the conduit.
Further, by traveling in an atmosphere with a more aerodynamically
favorable performance than air allows the vehicle to travel faster
than the speed of sound with respect to the air outside the conduit
without exceeding the sound barrier within the atmosphere. Thus,
for example, in a hydrogen atmosphere, which has a higher speed of
sound than air by a factor of 3.8, a delay in the onset of the
sound barrier is observed. Mach 1.2 in air corresponds to only Mach
0.32 in hydrogen. Hence, the vehicle may reach Mach 1.2 (with
respect to air) while remaining subsonic in the hydrogen
atmosphere. To "fly" the vehicle will involve utilization of a
levitation apparatus or a similar type of apparatus that supports
and guides the vehicle that cooperates with a guideway or support
and guide structure within the conduit such that the vehicle
levitates above the guideway or travels along the support and guide
structure within the conduit. The levitation or support and
guidance apparatus may, for example, include aerostatic gas
bearings, magnetic levitation, wheels, or small-diameter rollers,
like the rolling elements of roller bearings, or the like. In the
case of aerostatic gas bearings, a gas pump may be used to force
gas through the bearings to allow the vehicle to hover so that the
system does not depend on vehicle-guideway relative velocity to
provide gas pressure. At least one embodiment of magnetic
levitation, for example, AC-electromagnet levitation, can
analogously hover.
[0027] FIG. 1 illustrates a perspective view of a vehicle 100
conforming to aspects of the disclosure. The vehicle 100 includes a
body 102 supporting and housing various components of the vehicle,
including a wheel system 103 and a propulsion system 104. Generally
speaking, the body 102 assumes a cone-like aerodynamic shape.
Nonetheless, the body 102 may be any shape and similarly may be
constructed of any suitable material, including aircraft grade
aluminum or carbon-fiber materials. The body 102 is generally
cylindrical and tapering to a tip region 101. The propulsion system
104 in this embodiment is provided at the tip region 101 of the
vehicle 100. According to one specific example shown in FIG. 1, the
vehicle 100 can be a monolithic vehicle, similar to an airplane
fuselage and include two tandem propellers 105, one fore and one
aft of the vehicle.
[0028] Alternatively, as shown in FIG. 2, the vehicle 100 may
include a single propeller located only at one end of the vehicle.
Although the vehicle 100 shown in FIG. 2 may be used as a singular
vehicle, the vehicle 100 may also be part of a multi-articulated or
segmented vehicle, similar to a train as shown in FIG. 3. The
vehicle in FIG. 2 can be thought of as a "locomotive" in that it
includes the propulsion system as well as associated motors and
fuel systems, and additional unpowered cars may be coupled to the
vehicle or be placed between two vehicles 100 for cargo or
passenger transport. In other words, in the multi-articulated
configuration, the vehicle 100 can serve as a "locomotive" for
other cars, with one or more cars situated behind or in front of a
"locomotive," or between two "locomotives" located at each end of
the segmented vehicle. For instance, a first vehicle 100A may be
connected to a car 308 and a second vehicle 100B. The car 308 has a
levitation system 310, but it is not primarily designed to drive or
propel other cars 308 or vehicles 100A, 100B. The car 308 may be
configured to transport passengers, cargo, or both. The car 308 is
constructed out of a similar material to the body 102 of the
vehicle 100. The car 308 may have similar features to a passenger
portion of an aircraft. For example, the car 308 may have seats,
restrooms, a sink, a kitchen, and the like. The car 308 may connect
to other cars as well as to the locomotive vehicle 100 via a
coupler as discussed below. Although in FIG. 3 the car 308 is
illustrated as connected to two vehicles 100A and 100B, only one
vehicle 100 may be needed to pull a car 308, and the illustration
is merely one embodiment. For instance, the vehicle 100 may pull
car 308 by itself or the vehicle 100 may pull multiple cars 308 by
itself. Furthermore, in other embodiments, there may be multiple
cars 308 between vehicles 100A, 100B.
[0029] Referring again to FIG. 1, in one specific implementation,
the outside surface of the vehicle body 102 supports one or more
ailerons 111 that balance the vehicle when the vehicle is operated
at a speed that is above a minimum speed (V.sub.min) that may be
determined from the atmosphere within which the vehicle is to
operate and the shape of the vehicle. In one specific example, the
vehicle may include a pair of ailerons, with one aileron supported
on each side of the vehicle.
[0030] The wheel system 103, in one particular implementation, may
include one or more wheels 107 longitudinally aligned along the
bottom portion of the vehicle. The wheels are positioned and
configured to interact with the support and guide structure
provided within a conduit. In the specific example shown in FIG. 1,
the vehicle may include two wheels.
[0031] Alternatively, as shown in FIGS. 2 and 5, the vehicle may
include a levitation system 303 along the bottom portion of the
vehicle instead of the wheel system 103. In one specific example
the levitation system may include an aerostatic gas-bearing
arrangement. Alternatively, the levitation system may be a magnetic
levitation system. For the vehicle to operate in an enclosed
structure, tube or generally a conduit, it needs to be
appropriately dimensioned to fit in such a structure. In one
specific example, when a vehicle operates in a circular tube with a
diameter of approximately 8 meters, the vehicle may have a diameter
of 2.8 meters and be 23 meters long. It is possible that the tube
may have other shapes, besides circular, such as rectangular, a
square, and may include one or more vehicle pathways.
[0032] As shown in FIGS. 1 and 2, the vehicle 100 includes some
form of a propulsion system 104. In the embodiment discussed
herein, the propulsion system 104 involves a propeller arrangement
105 that propels the vehicle 100 within the gas-filled conduit. The
propeller arrangement 105 may have a single set of rotating blades,
contra-rotating blades, axial-fan blades, or any other blade
configuration suitable for propelling the vehicle 100. The
propeller arrangement 105, in one implementation includes two sets
of blades 109, 110 that rotate along a centerline 112 of the body
102 of the vehicle 100 with each set rotating in opposite
directions with respect to the other. However, in other
implementations, the propeller arrangement 105 may include a single
set of blades that rotates in a single direction, may include fore
and aft blades, sets of blade, etc. In some embodiments the
propeller arrangement 105 may have a diameter of approximately 4
meters.
[0033] In general, the design of the propeller arrangement 105 may
be optimized for the environment in which it will operate. In
particular, the propeller arrangement may be designed in accordance
with the size of the conduit and/or the atmosphere within the
conduit, among other parameters. For example, the diameter of the
propeller arrangement 105 may be a function of the size of the
conduit and may be increased or decreased as the conduit diameter
or size is increased or decreased. Furthermore, for a given
operating atmosphere, rotational frequency, number of blades in the
propeller arrangement, and/or diameter may be optimized to achieve
satisfactory propeller static thrust, power loading, and
efficiency.
[0034] In one particular example, propeller arrangement design may
involve optimizing rotating frequency of the blades and the number
of blades for a given propeller diameter. In general, propeller
efficiency is defined as:
.eta.=TV/P.sub.s
where T is thrust, V is the velocity of the vehicle, and P.sub.s is
the shaft input mechanical power. For a single propeller, the
Rankine-Froude momentum theory of propulsion assumes that the
operating gas is accelerated by an infinitely thin "actuator disc"
of area S that provides energy to the gas but offers no resistance
to gas as it passes through it. In unit time, the mass of gas
passing through the actuator disc is:
m=.rho.SV.sub.o
where .rho. is density of the gas, and V.sub.o is the gas velocity
at the immediate rear of the disc. The increase of momentum of the
mass of fluid, and hence the thrust T on the disc is
.DELTA.(mv)=T=.rho.St/.sub.o(V.sub.s-V)
where V is the gas velocity far ahead of the disc, V.sub.s the gas
velocity far behind the disc. Therefore, after several steps of
derivation, the ideal efficiency (.eta..sub.i) of the actuator disc
is given by:
.eta.=2/(1+V.sub.s/V)
Similarly, the Rankine-Froude momentum theory when applied to
contra-rotating tandem propellers assumes that the propeller be an
ideal actuator disk with an infinite number of blades which
exhibits no resistance to gas flow, transfers all mechanical energy
to the gas, and experiences a uniform distribution of gas pressure
and velocity over its surface. With the flow velocity V.sub.f
through the front disk being defined as:
V.sub.f=1/2(V+V.sub.s)
where V is flow velocity far ahead of the disk (i.e., vehicle
velocity, or initial inflow velocity, within the vehicle-fixed
frame of reference) and V.sub.s is the fully-developed slipstream
velocity far behind the disk, the mass flow through the front disk,
in unit time increment, becomes:
m=1/2.rho.S(V+V.sub.s)
where .rho. is density of the gas and S is an area of the disk.
Thus, thrust provided by the front disk of tandem pair is:
T.sub.f=.rho.S(V.sup.2+V.sub.s.sup.2)/2
and the power required by the front disk being given by:
P.sub.f=(.rho.S(V.sub.s.sup.2-V.sup.2)(V.sub.s+V))/4
Because for the rear disk in the tandem configuration the initial
inflow velocity V' may be greater than V, and its final slipstream
velocity Vs' may be greater than Vs, the thrust and power for the
rear disk differ from those for the front disk. Taking this into
consideration and after several steps of derivation it can be shown
that for a rear disk the thrust is given by:
T.sub.r=.rho.S(V.sub.s.sup.2-V.sup.2)(((1-.omega.)V+.omega.V.sub.s)/V).s-
up.2/2
and power by:
P.sub.r=.rho.S(V.sub.s.sup.2-V.sup.2)(V.sub.s+V)(((1-.omega.)V+.omega.V.-
sub.s)/V).sup.3/4
where .omega. is the probability that a streamline in the
slipstream from the front disk will intersect the rear disk defined
by .omega.=A/A.sub.t where A is the area of the rear actuator disk
and A.sub.t is the cross-sectional area of the tube. Extending the
Rankine-Froude propulsive efficiency to contra-rotating tandem
propellers, thus, results in the propulsive efficiency for the
tandem pair configuration being defined as:
.eta.=V(T.sub.f+T.sub.r)/(P.sub.f+P.sub.r)
where V is vehicle velocity, T.sub.f and T.sub.r are the thrust
provided by the front and rear disks, respectively, and P.sub.f and
P.sub.r are the slipstream power required by the front and rear
disks, respectively. Substitution of the power and thrust required
by the front and rear disks, P.sub.f, P.sub.r, T.sub.f and T.sub.r
gives:
.eta.=(2V/(V.sub.s+V))((V.sup.3+V[(1-.omega.)V+.omega.V.sub.s].sup.2)/(V-
.sup.3+[(1-.omega.)V+.omega.V.sub.s].sup.3))
as the propulsive efficiency for tandem disks in a tube. Additional
details related to propeller design discussed herein may be found
in "Hydrogen tube vehicle for supersonic transport: 4 Hydrogen
propeller" by Arnold Miller published in the International Journal
of Hydrogen Energy 37 (2012) 14603-14611, which is hereby
incorporated by reference herein.
[0035] An important fact shown by these equations is that the
propeller efficiency is independent of gas density. Thus, the
efficiency of the propeller will not necessarily be changed by
operating in hydrogen or any other atmosphere rather than in air.
However, a different propeller diameter, rotational frequency,
wider and/or more blades may be required to attain the same
efficiency and thrust as a propeller operating in air. Hence, for
example, in case of a hydrogen atmosphere, a different (larger)
propeller diameter, higher rotational frequency and/or more blades
may be required to attain the same efficiency and thrust as a
propeller operating in air. One specific hydrogen propeller design
may employ 14 contra-rotating blades, 4.11 m diameter, and
rotational frequency of 40.4 s.sup.-1 at translational velocity of
970 m/s. The same is true for water propellers compared to air
propellers: waterborne ship propellers are of similar efficiency
but are smaller and slower-turning than comparable-power airplane
propellers.
[0036] Additionally, from consideration of the kinetic-energy
imparted to the slipstream, which preferably is minimized, the
larger the diameter of propeller arrangement 105, the greater the
potential propeller efficiency. However, as the diameter increases
for a given rotational frequency (speed), the propeller tips will
eventually enter the transonic region, and the considerations
discussed above regarding dynamic instability and high power
associated with the transonic region will apply to the propeller
blades. Moreover, because the propeller traces out a helix as the
vehicle advances, a vector component of rotational velocity should
be added to vehicle translational velocity, and hence the blade-tip
velocity exceeds the vehicle velocity. It is for this reason that
propeller tip speed limits the speed of a propeller-driven vehicle,
and a higher propeller diameter may require a lower rotational
frequency.
[0037] Although the propulsion system may include a propeller
arrangement 105, other forms of propulsion may be used in place of
the propeller arrangement 105. For instance, the vehicle 100 may be
powered by a motor, engine, and the like. If the vehicle 100 uses
magnetic levitation, then the vehicle 100 may alternatively be
propelled by a linear synchronous or linear induction motor. The
stator of such a linear AC motor may be either on the vehicle 100
or on the guideway 302 (see FIG. 7); the linear equivalent of the
rotor of a rotating AC induction or synchronous motor will be
placed on the element opposite the stator. For example, if the
stator is placed on the vehicle 100, then the linear-equivalent of
the rotor will be placed on the guideway 302.
[0038] FIG. 4 illustrates a prospective view of the vehicle 100
shown in FIG. 1 within a conduit 400. In the particular example
shown, the conduit may comprise a tube 406 with a circular
cross-sectional area. The vehicle 100 may travel through the tube
406 along a vehicle support and guide structure 402 located along
the bottom of the tube 406. In the illustrated example, the support
and guide structure may be a single rail 404 that is constructed
from steel or any other suitable material. The rail 404 may be
integral to the tube but may also be a separate structure that may
be attached to the tube 406 by welding, fasteners, or other methods
of attachment.
[0039] According to another implementation shown in FIGS. 2 and 5,
when the vehicle 100 includes a levitation system 303 instead of
the wheel system, the vehicle 100, in effect, flies within the tube
406. The vehicle 100 does not, however, have conventional wings.
Instead, the vehicle 100 is elevated by way of the levitation
system 303, which in one particular implementation is an aerostatic
gas-bearing arrangement. The tube 406, as discussed herein, may
include or otherwise define a guideway 302, or "vee-way" that
matches the shape of the aerostatic bearings or other levitation
system 303. The term "vee-way" derives from the terminology of
machine tools (c.f., the "ways" or "vee-ways" of a lathe), and in
this disclosure, the shape of the "way" is not necessarily in the
shape of a "V" but could have other shapes such as a semicircle (or
"U") or a rectangle. Similar to the rail 404 discussed above, the
guideway 302 is not necessarily integral to the tube but may be a
separate structure that may be attached to the tube 406 by welding,
fasteners, or other methods of attachment. When the levitation
system 303 includes an aerostatic gas-bearing arrangement, the
aerostatic gas-bearing arrangement forces gas, or other fluids,
through small orifices against a surface of the guideway 302, such
as a vee-way, and thereby creates a small gap between the bearings
and the vee-way to levitate the vehicle 100 within the tube 406.
This arrangement in effect allows the vehicle to "fly" within the
tube.
[0040] In yet another implementation, the vehicle 100 may travel
through the tube 406 while supported by magnetic levitation, with
appropriate magnetic system components included on the vehicle as
well as the guideway 302. The tube 406 will have an appropriate
guideway, generally analogous to the above-described vee-way for
aerostatic gas-bearing levitation, and the vehicle 100 levitates
above the guideway on a magnetic field rather than a fluid film. In
these embodiments, the guideway includes magnetic material and the
vehicle 100 has magnetic materials installed on the bottom of the
vehicle 100, for instance, where the levitation system 303 is
located. The guideway 302 may, for example, include tracks that
have wires, solenoids, conducting materials, magnets, or may
otherwise produce a magnetic field in order to produce levitation
and/or propulsion of the vehicle 100.
[0041] FIG. 6 illustrates an isometric view of a portion of the
tube 406 with a guideway 302. The tube 406 is generally
cylindrical, including an inner diameter 602 and an outer diameter
606. In the example shown, the guideway 302 is a V-shaped guideway
provided along a bottom portion of the tube. The guideway, as shown
also in FIG. 5, is not necessarily integral to the tube but may be
the equivalent to a V-shaped (or otherwise-shaped) rail or track
running along the bottom of tube 406. The inner diameter 602 may be
any suitable dimension to provide a conduit for various possible
vehicle 100 diameters. In one particular embodiment, the inner
diameter 602 may be approximately 5 meters. This diameter (5
meters) is able to accommodate an embodiment of the vehicle 100
having a 2.69 meter fuselage diameter and a propeller diameter of
approximately 4 meters. This inner diameter 602 allows the vehicle
100 to fit inside the tube 406 while maintaining a gap between the
wall of the inner diameter 602 and the vehicle 100 and its
propellers 109, 110. This configuration allows the vehicle 100 to
levitate above the bottom of the tube 406 and for hydrogen or any
other gas to pass between the consist or trainset and the inner
surface of tube 406 when the vehicle 100 is at speed. The outer
diameter 606 forms the outside of the tube 406 and may be any size
larger than the inner diameter. Additionally, as the tube 406 may
be located either above ground, underground, or under water, the
outer diameter 606 may be in contact with the surrounding elements,
whether those elements be air, dirt, rocks, or water. Therefore, in
some embodiments, the outer diameter 606 may include additional
layers of insulation or protective materials to prevent wear and
tear of the tube 406 due to outside elements. These additional
layers may be concrete, plastic, composite materials, ceramics,
metals, or any combination of similar materials.
[0042] The guideway 302 or any other similar support and guide
structure may be used to support a track or other guidance system
for the vehicle 100. In some embodiments, the guideway or any other
similar support and guide structure may be located at the bottom of
the tube 406, in other embodiments the guideway 302 or any similar
support and guide structure may be located on the sides or top of
the tube 406. In some embodiments, the guideway or any other
similar support and guide structure may be used to support a rail
system and may provide a track or tracks to support and guide the
vehicle 100. The guideway 302 may be shaped in any manner, however
in some embodiments the guideway 302 may be shaped as the letter
"V" or as the letter "U".
[0043] FIG. 7 shows a schematic of magnetic levitation of the
vehicle within the tube 406. Conforming to the shape of the
vee-way, which may be in other shapes than a "V," as discussed
above, are continuous metal sheets 701, 703, shown in cross-section
in FIG. 7, running the length of tube 406. The metal should be of
high electrical conductivity, and aluminum is an appropriate (but
not limiting) material. Magnets 702, 704 replace the segments of
the gas bearings in the vehicle that includes an aerostatic gas
bearings arrangement. Several kinds of magnets may be used, for
example, permanent magnets, superconducting magnets, AC
electromagnets, or DC electromagnets. Embodiments of these are
described as follows. When magnets 702, 704 are permanent or
superconducting magnets, the relative velocity of the vehicle over
the conducting sheets 701, 703 induce electrical currents and hence
magnetic fields in the sheets. The induced magnetic fields in
sheets 701, 703 are of the same-polarity (or "like-polarity") to
the magnets on the vehicle (e.g., N on the bottom of levitation
system 303 and also N on the top of sheet 701, 703), and the
resulting N--N or S--S repulsion levitates the vehicle. The faster
the relative velocity of vehicle 100 and sheets 701, 703, the
stronger the induced field and the greater the potential height of
the levitation gap between magnets 702, 704 and metal sheets 701,
703. When the vehicle is stopped there can be no induction and the
levitation gap is zero. Hence, embodiments employing permanent or
superconducting magnets employ "landing wheels" or some other
mechanism to support the vehicle as it approaches and attains zero
speed. Magnetic levitation may be used by itself or in combination
with gas-bearing levitation.
[0044] The embodiment employing AC electromagnets is similar to the
aerostatic gas-bearing embodiment. Alternating current in the
solenoids of the AC electromagnets induces alternating
same-polarity magnetic fields in metal sheets 701, 703. The
same-polarity (N--N or S--S) of the electromagnet fields and
induced fields produces levitation of vehicle 100. Like the
aerostatic gas bearings discussed above, the AC magnetic levitation
allows the vehicle to hover because the magnetic fields induced in
the conductive sheets 701, 703 are due to the alternating current
in the solenoids of electromagnets 702, 704 rather than relative
motion of the vehicle. The AC-electromagnets 702, 704 may use
feedback control of AC-solenoid current to control the gap height
between magnets 702, 704 and the conductive sheets 701, 703 and
hence the height of the vehicle above the sheets.
[0045] There is a type of DC magnetic levitation that can also
provide hovering. In such an embodiment, the vehicle could be
suspended below a ferromagnetic rail and an appropriate gap between
the rail and DC magnets on the vehicle 100 would be provided
through feedback control of the solenoid DC current. While this
embodiment could require a very different design of the
guideway--namely, a ferromagnetic rail rather than aluminum sheets
on a vee-way--this is also a viable embodiment for magnetic
levitation of vehicle 100.
[0046] The vee-way, with attached, conforming metal sheets or
alternatively a ferromagnetic rail, then guides the vehicle 100
through the tube 406. The magnetic levitation apparatus conforms
generally to the shape of the vee-way or ferromagnetic rail so that
the vee-way or rail can guide the vehicle 100 through tube 406.
[0047] Although, as discussed above, the conduit may be configured
as a tube with a circular cross-section, alternatively the conduit
may have a "waisted circle" configuration with a cross-section of a
fluted or grooved tube as shown in FIG. 8. The fluted tube 800,
which is a single tube with grooves or waists 802 along its length,
could offer a number of benefits. First, increasing or maximizing
the cross-sectional area of the tube relative to the vehicle may
help to reduce aerodynamic drag, with the shared central part of
the fluted tube acting as a plenum for vehicular flows. Second,
when used in a system that allows either bidirectional or parallel
transit, the fluted tube configuration may help minimize
infrastructure costs. Additionally, as shown in FIG. 8, the
"waisted circle" cross-section, by partially wrapping the tube
around each vehicle provides structural stiffness to the tube. The
"waisted circle" configuration also simplifies placement of a
support and guide structure 402, as well as mitigates inference
flow between passing vehicles.
[0048] One method of forming a fluted tube configuration may
involve joining two or more separate, circular-section tubes, along
their length to form a single fluted tube with grooves or waists
along its length. In the specific example shown in FIG. 8, the
fluted tube may be formed by conjoining three tubes such that the
fluted tube includes three waists or local minima in the distance r
from the pole when the shape is described as a polar equation
r=f(t), where t is the angle. Although, the fluted tube
configuration shown is formed from joining three tubes, a fluted
tube formed from more or fewer tubes is also possible. A more
detailed discussion of the theoretical basis for the fluted tube
design may be found in the "Fluted Tubes and Waisted Circles" paper
by Arnold Miller published in the Int. J. of Mathematical Sciences
and Applications, Vol. 1, No. 3, September 2011, which is hereby
incorporated by reference herein.
[0049] Regardless of the tube configuration, the tube is built to
the appropriate dimensions such that the vehicle 100 (or vehicles
in case the tube is designed to support a bidirectional transit)
can fit completely inside the tube. The tube may be constructed
similarly to a pipeline for natural gas, oil, or water. For
instance, the tube may be constructed of concrete, metal or other
suitable materials. The tube may also include various types of
seals to prevent the gas 407 filling the tube from escaping the
tube. The seals may be any type of conventional material used to
prevent air/gas from escaping an enclosed area. For instance,
sealing may be provided by elastomers, concrete layers, rigid
panels, or the like. The tube may inherently have sufficient
gas-tight properties (e.g., a welded metal tube) so as to not
require additional/separate seals. In some embodiments, the tube
may be sealed in order to create a consistent environment for the
vehicle 100 to travel, as well as to prevent impurities from
entering the tube. Furthermore, in these embodiments, the tube may
also contain air locks or other sealed entryways that allow the
tube and vehicle 100 to be accessed from different locations.
[0050] In addition, the tube may also include a purification system
to remove impurities, such as water that inadvertently slips
through the vehicle water-collection system when, for example,
hydrogen is used as the tube atmosphere or air that escapes around
the air-lock seals, as well as any other unwanted materials, from
the atmosphere 407 within the tube. In case of a hydrogen
atmosphere, the purification system may utilize conventional
purification hardware, such as pressure-swing-absorption, hydrogen
palladium filters, or hydrogen catalytic combustors, through which
the tube hydrogen may slowly pass. Analogous purification systems
may be used for any of the other gases disclosed below.
[0051] The operating atmosphere inside the tube is selected to
achieve aerodynamic tunneling that has the potential of enabling
high-efficiency, quiet, supersonic transport. In particular, the
atmosphere is selected to increase the speed of sound so that,
although it is not necessary for the vehicle to travel at
supersonic speed, its speed at a given Mach number will correspond
to a higher absolute speed (ms.sup.-1). The selected atmosphere
will also have a lower gas density and/or viscosity so that drag is
reduced. In other words, the ideal properties of such a gas are
that the absolute speed be higher and density be lower than that of
air at a given Mach number and pressure: The speed of sound in a
gas increases as the density decreases, and the drag decreases as
the density and viscosity decrease. Also, the potential operating
atmosphere may be able to serve as a fuel for the propulsion fuel
cells for vehicle 100 operating inside of the conduit. One method
of determining the potential operating atmosphere for use inside
the conduit may involve determining aerodynamic (tunneling)
performance of the atmosphere and energy density of the tube
vehicle with the product of the two parameters determining the rank
of atmospheric merit. Alternatively, the potential operating
atmosphere may be determined based on gas efficacy (), with higher
efficacy indicating higher speed and/or reduced drag. In
particular, the higher the efficacy, the more the gas increases the
Mach 1 speed or reduces drag. Based on the criteria of speed and
drag, gas efficacy can be defined as:
=c/D
where c is speed of sound (m s.sup.-1) in the gas and D is drag (N)
on an ideal flat plate used as an aerodynamic test body in the tube
atmosphere. An important fact to note from this equation is that
the efficacyincreases as the first power of absolute speed at Mach
1, and varies inversely as the first power of skin-friction drag
for laminar flow over the plate. With the speed of sound for the
ideal gas given by:
c=(.gamma.p/.rho.).sup.1/2
where .gamma. is the ratio of specific heats, p is constant tube
pressure, and .rho. is tube gas density. Friction drag on either
face of a rectangular flat plate of infinitesimal-thickness is
given by:
D=1/2(CpV.sup.2bL)
where C is the friction drag coefficient, V is speed of the plate
(or of the flow), b is width of the plate, and L is the length
parallel to the flow, the gas efficacy after several steps of
derivation, can be shown to be equal to
=2/(1.328(.gamma.p).sup.1/4.rho..sup.1/4.mu..sup.1/2)
where .mu. is gas viscosity. Substituting thermo-physical
properties of various gases into the above equation provides
ranking of the gases for their potential use as a conduit
atmosphere based on the gas efficacy parameter. Examples of
potential conduit atmosphere gases ranked using gas efficacy
parameter are shown in Table 1. Although gases listed in the table
can be used individually, use of a mixture of any of the listed
gases as the tube atmosphere is also contemplated. Additional
information on the methods for determining potential gases for tube
atmosphere can be found in the "Aerodynamic Tunneling" article by
Arnold Miller submitted to and accepted for presentation at the
World Hydrogen Technologies Conference, to be held in Shanghai,
China, from 25-28 Sep. 2013, as well as "Hydrogen tube vehicle for
supersonic transport: 3. Atmospheric merit" article by Arnold
Miller published in International Journal of Hydrogen Energy 37
(2012) 14598-14602, which are hereby incorporated by reference
herein.
TABLE-US-00001 TABLE 1 Gas parameters and efficacy .GAMMA. Mol. Wt.
c.sup.b .rho..sup.d .GAMMA. Gas.sup.a g/mol m s.sup.-1
.gamma..sup.c kg m.sup.-3 .mu..sup.e .times. 10.sup.6 Pa s s
kg.sup.-1 H.sub.2 2 1310 1.384 0.0824 8.90 48.7 Air 29 295 1.4
0.364 14.14 38.7 (11 km).sup.i NH.sub.3 17 415 1.310.sup.f
0.73.sup.g 9.80.sup.h 27.3 CH.sub.4 16 450 1.305 0.6556 11.10 26.3
He 4 965 1.664 0.1636 19.90 26.2 C.sub.2H.sub.2 26 329 1.260.sup.g
1.11.sup.g 9.54.sup.h 25.1 C.sub.2H.sub.6 30 312 1.193 1.2291 9.40
25.0 C.sub.3H.sub.8 44 258 1.134 1.8025 8.30 24.5 C.sub.2H.sub.4 28
331 1.242.sup.g 1.1465 10.30 24.1 HCl 36 296 1.41.sup.f 1.56.sup.g
13.20.sup.h 19.1 SO.sub.2 64 213 1.282 2.77.sup.g 11.58.sup.h 18.07
CO 28 338 1.402.sup.g 1.1449 17.80 17.8 N.sub.2 28 353 1.403 1.1449
17.90 17.7 CO.sub.2 44 259 1.293 1.7989 14.90 17.7 N.sub.2O 44 263
1.27.sup.f 1.872.sup.g 15.00 17.6 Air (sea 29 340 1.4 1.2256 17.83
17.5 level).sup.i Cl.sub.2 71 206 1.34.sup.f 3.04.sup.g 12.45.sup.h
16.8 NO 30 325 1.386.sup.f 1.27.sup.g 19.20 16.7 O.sub.2 32 330
1.393 1.3080 20.70 16.0 CCl.sub.2F.sub.2 121 140 1.138.sup.j
5.11.sup.g 11.68.sup.h 15.9 F.sub.2 38 332 1.352.sup.f 1.59.sup.g
24.60 14.0 SF.sub.6 146 133 1.09.sup.k 6.27.sup.g 14.20.sup.h 13.8
Ar 40 323 1.664 1.6329 22.70 13.8 Ne 20 435 1.650.sup.f 0.853.sup.g
32.10 13.7 .sup.aRanked by decreasing order of .GAMMA.. Temperature
T = 298-300 K unless otherwise noted. Pressure for all gases =
101.3 kPa, except for air at 11 000 m, which is at 22.6 kPa [9].
.sup.bSpeed of sound from [10-12]. .sup.cSpecific-heat ratios from
[13] except NO, N.sub.2O, NH.sub.3, HCl from [14] and Cl.sub.2 from
[15]. .sup.dDensities from [13] except H.sub.2, He, CH.sub.4, CO,
N.sub.2, C.sub.2H.sub.4, C.sub.2H.sub.6, O.sub.2, Ar, CO.sub.2,
C.sub.3H.sub.8 from [10], p. 8-135. .sup.eViscosities from [10], p.
8-135, except N.sub.2O from [10] p. 6-190, and also NH.sub.3,
C.sub.2H.sub.2, HCl, SO.sub.2, Cl.sub.2, CCl.sub.2F.sub.2,
SF.sub.6, from [13] and F.sub.2 from [16]. .sup.fT = 293-294 K.
.sup.gT = 273 K. .sup.hT = 288-290 K. .sup.iPhysical properties of
the standard atmosphere [9, 17] at altitude z indicated. T = 288 K
at z = 0; T = 217 at z = 11 km. Viscosity of air at 11 000 m also
reported as 14.2 Pa s [18]. .sup.jT = 303 K. .sup.kCalculated from
R = C.sub.p - C.sub.v, where R is the gas constant and C.sub.p and
C.sub.v are heat capacities at constant pressure and volume,
respectively. C.sub.p = 0.097 kJ mol-1 K-1 at 100 kPa and 294 K
[13].
[0052] In one specific implementation, the conduit atmosphere may
contain hydrogen that was determined as having both highest overall
merit as well as gas efficacy. In the particular embodiment
discussed herein, this hydrogen gas environment provides the
vehicle 100 with its fuel, and the tube hydrogen consumed by the
vehicle is replaced from a source of hydrogen outside the tube.
Hydrogen 407 is used within conduit 406 as the vehicle 100 can
travel within the hydrogen atmosphere at supersonic speed with
respect to air outside the tube while remaining subsonic inside the
tube; the low density and viscosity of hydrogen results in lower
drag for the vehicle relative to the outside air; and the high
thermal conductivity of hydrogen facilitates heat rejection from
the vehicle compared to heat rejection to atmospheric air and
especially to reduced-pressure air.
[0053] The hydrogen 407 within the tube 406 may be maintained at a
pressure slightly above atmospheric pressure. For example, the
pressure within the tube may be maintained at about 0.05 bar above
ambient atmospheric pressure. The relatively higher pressure inside
of the tube assures that hydrogen 407 would leak out of the tube
through any inadvertent breach (e.g., crack, pinhole leak in a
weld, or similar breach) in the tube, rather than have the outside
air atmosphere and other elements leak into the tube, thereby
maintaining a safe working environment for vehicle 100. An
objective of not allowing air to leak into the tube is that by
keeping the concentration of hydrogen at or above 75% (by volume),
the hydrogen 407 will be held above the upper flammability limit of
hydrogen and the hydrogen 407 will be too rich to burn. This method
of safety also applies to any of the other flammable gases (see
Table 1 above) that may be used as tube gases because of increased
gas efficacy, although the upper flammability limit will vary for
each gas.
[0054] One embodiment of an atmosphere alternative to hydrogen is
methane, or natural gas, which is substantially methane. The
density of methane at a given pressure is about half the density of
air at the same pressure, and methane can be used as a fuel for
fuel cells. As for hydrogen above, the pressure of the methane
within the tube may be maintained slightly above air pressure
outside the tube, and thereby any inadvertent leakage through tube
would be leakage of methane to the outside of the tube rather than
leakage of air into the tube. Analogous to the substantially
hydrogen-filled tube, an objective of not allowing air to leak into
the substantially methane-filled tube is that by keeping the
concentration of methane at or above about 17% (by volume), the
methane will be held above the upper flammability limit of methane
and the methane within the tube will be too rich to burn. The
methane breathed by the vehicle 100 may be converted to hydrogen
onboard the vehicle 100 by a steam reformer, or similar chemical
processor, and the hydrogen then supplied to the fuel cell to
provide propulsion power; alternatively, some fuel cells, for
example, solid-oxide fuel cells, may operate directly on methane.
In this embodiment using methane as the atmosphere within the tube,
the products of the chemical processes onboard the vehicle 100 are
substantially both water and carbon dioxide, and in one embodiment,
the carbon dioxide may be chemically trapped onboard the vehicle
100 and thereby not released into the tube 406. The technique may
use any method of trapping carbon dioxide, for example, converting
it to a liquid or solid or chemically trapping it as a product such
as a carbonate. In the case of trapping the carbon dioxide as a
carbonate, the carbon dioxide may be readily reacted with a strong
base such as calcium hydroxide to give the solid calcium carbonate.
In this embodiment, the trapped carbon dioxide may be stored
onboard the vehicle 100 until the end of a run, at which time it
would be removed from the vehicle 100 to make room for more trapped
carbon dioxide on a subsequent run of the vehicle 100.
[0055] Another possible gas for use within the tube is helium.
Having a density twice that of hydrogen but about seven times less
than air and having a viscosity about the same as air, it would
provide a lower operating gas density than air for the vehicle 100
and would thereby give a higher sonic speed and lower drag than air
outside the tube. However, it would not be as good in this regard
as hydrogen, and because helium is an inert gas, it would not be
useable as a fuel for the onboard propulsion fuel cells of the
vehicle 100.
[0056] While the use of a single high-efficacy gas for the tube
atmosphere is desirable in order to achieve higher speed and/or
reduced drag, in some instances these gases may provide relatively
low thrust for a propeller and therefore possibly result in low
acceleration of the vehicle. The same consideration applies to
braking of the vehicle by the propeller. This is due to the fact
that the propeller thrust is a function of the first power of gas
density as shown and discussed above. Low acceleration could limit
the system to long-range applications (thereby allowing sufficient
distance to accelerate to cruise speed), or limit the weight of the
vehicle, or limit the achievable speed of the vehicle. One possible
method for overcoming this potential limitation of the
high-efficacy gases is to utilize gases with different densities in
different parts of the tube so as to create "density stages."
[0057] The schematic in FIG. 9 and a numerical example in the
accompanying Table 2 provide an example implementation of density
stages. It should be noted that the gases used in this description
and the shape of the conduit are presented as one example of the
method of density stages and are not intended to be limiting in any
way. Thus, for example, the density stages could be also used in a
fluted tube configuration and/or the stages could be used in
different parts of the tube to assist with accelerating as well as
braking of the vehicle. In the specific example shown, the tube is
divided into three sections. The three sections of gray tubes shown
(not to scale) may represent a portion of the tube or conduit
within which the vehicle accelerates. The left-most section 902 is
termed "Stage 1" (shown as the darkest gray color); the central
section 904 is termed "Stage 2" (intermediate gray color), and the
right-most section 906 is termed "Stage 3" (lightest gray color).
Each section or stage contains a different gas: Stage 1 contains
the dense gas sulfur hexafluoride (denoted as SF6 in the figure);
stage 2 contains the less-dense gas methane (denoted CH4); and
stage 3 contains the low-density gas hydrogen (denoted H2). Other
gases, such as for example, carbon tetrafluoride (CF.sub.4),
1,1,1,2-tetrafluoroethane (CF.sub.3CFH.sub.2), halocarbon 23,
halocarbon 116, halocarbon C318, halocarbon 218, halocarbon 32,
halocarbon 125 halocarbon 134A, halocarbon 21, halocarbon 22, and
other halocarbons and similar dense gases may also be used as
conduit (or tube) gases in different stages because of their high
density. Also, mixtures of any of the gases in Table 1, or mixtures
of any of the dense gases just mentioned, or mixtures of any
combination of gases from Table 1 and the dense gases just
mentioned, may be used as the conduit atmosphere, in any stage or
in the entirety of the tube. The achievable speed of the vehicle,
at a given Mach number, increases as it traverses from Stage 1 to
later stages because the speed of sound in a gas is a decreasing
function of density. The stages are separated by movable doors 908,
910 that substantially act as partitions between the stages and,
when closed, prevent mixing of the gases. In one implementation,
the doors are mechanical irises (shown as Iris 1 and Iris 2 in the
figure), but sliding doors, or a door, barrier, partition with any
mechanism that allows it to open and close quickly can be used, and
"iris" is intended to be descriptive of the function and not
limiting. For braking, at the other end of the tube, the sequence
of densities would be in the opposite order, going from less dense
to more dense.
[0058] As an example of the operation of density stages, consider
that the tube vehicle commences its transit from the left-most part
of the three-stage tube shown in FIG. 9. Because the density of
sulfur hexafluoride is 76-times denser than hydrogen, the propeller
thrust in Stage 1 can be 76 times what the thrust would be if the
tube contained only hydrogen. Since acceleration for a given mass
of vehicle is proportional to thrust, the acceleration in Stage 1
can be 76 times what the acceleration would be in an un-staged tube
with only hydrogen, for example. The system is arranged so that the
vehicle approaches the end of Stage 1 and hence Iris 1 at the same
time that it approaches its limiting speed in Stage 1 (i.e. a given
Mach number). At this point, Iris 1 opens, allowing the vehicle to
enter Stage 2, and then closes behind the vehicle. The vehicle
continues its transit in Stage 2 until it approaches its limiting
speed in Stage 2. Once the vehicle reaches the end of Stage 2, Iris
2 opens and then closes after the vehicle passes, allowing the
vehicle to enter Stage 3 and thereby continue its transit within
the tube.
[0059] In another implementation, Iris 1 and Iris 2 are each
comprised of a pair of irises. The first pair of irises may
straddle the location of Iris 1 in FIG. 9, and the second pair of
irises may straddle the location of Iris 2. By having a relatively
short section of tube between a first iris and a second iris of
each of the pair of irises, each pair of irises acts as a gas-lock
and reduces mixing of the gases in the various stages as the
vehicle passes between the stages. As the vehicle approaches the
first iris of the first pair of irises, the first iris opens and
closes and thereby captures the vehicle in the relatively short
section of tube between the first and the second iris of the first
pair of irises. The second iris of the first pair then opens and
closes, allowing the vehicle to enter Stage 2. A similar operation
occurs for the pair of irises that straddle the location of Iris 2
in the figure. A pair of irises thus prevents direct flow of gas
between any two stages as the vehicle passes between stages.
[0060] Table 2 set forth below gives a numerical example of the
benefits of multiple stages. In this example, which is not intended
to be restricting in any manner, assume that the limiting speed in
each stage is Mach 0.74, and the acceleration in the hydrogen stage
is 2.4 m/s.sup.2 which may be constant. The accelerations in Stages
1 and 2 are also constant and are proportional to their respective
gas densities (see Table 2) compared to hydrogen; thus, the
acceleration in Stage 1 is (6.27/0.0824) 2.4 m/s.sup.2=182.6
m/s.sup.2, and the acceleration in Stage 2 is (0.6556/0.0824) 2.4
m/s.sup.2=19.1 m/s.sup.2. With these parameters, the time and
distance to traverse each stage, as well as the total time and
distance (the sums of the times and distances in the separate
stages), are calculated from the standard equations in physics for
acceleration of masses and are given in Table 2.
[0061] If the tube included only a single gas, such as, for example
hydrogen, the time required to reach 969 m would be 404 s, and the
distance required to reach this speed would be 195,778 m. Thus,
using the three stages in the example results in substantial
reductions in the vehicle's total time and distance: Time is
reduced from 404 s to 278 s, and distance is reduced from 195,778 m
to 85,843 m. Reduced time would result in faster service for
passengers or cargo; in some implementations, reduced distance to
reach cruise speed allows the vehicle more length of its tube for
cruise speed and braking, as well as reduces the mass and cost of
the dense gases of the acceleration stages. The greater the number
of stages in the method of density stages, the larger the reduction
of time and distance.
TABLE-US-00002 TABLE 2 Density stages Limiting Time to Distance to
speed Density traverse reach end Stage Gas m/s kg/m.sup.3 stage s
of stage m 1 SF.sub.6 98 6.27 0.5 s 27 2 CH.sub.4 333 0.6556 12.3
1441 3 H.sub.2 969 0.0824 265.2 84,376 Total: 278 s 85,843 m
[0062] The discussion will now turn to some of the functional
components of the vehicle 100. FIG. 10 is a block diagram
illustrating the functional components of the vehicle 100 shown in
FIG. 2. Discussing first the front of the vehicle 100, the
propeller arrangement 105 provides vehicle propulsion. The
propeller arrangement 105 includes a first set of blades 109 and a
second set of blades 110, and these blades 109, 110 are configured
to rotate about a common axis 112 defined generally along the
longitudinal centerline of the vehicle 100. Each set of blades is
coupled with a common propulsion motor 1004, although distinct
propulsion motors for each set of blades 109 or 110 are possible.
The propulsion motor(s) 1004 may be either DC or AC electric
motors, hydraulic motors, or the like. The first and second sets of
blades 109, 110 each can include a number of blades that is
optimized for the atmosphere in which they operate. In the example
shown, the first and second sets of blades each include six blades
concentrically and evenly spaced about the common axis. The motor
1004 drives the first set of blades 109 in one direction, e.g.,
clockwise, and the second set of blades 110 in the opposite
direction, e.g., counterclockwise. In this arrangement, the
contra-rotating blades help to reduce energy losses due to the
unproductive rotation of the slipstream, and this arrangement is
more efficient than propellers having a single set of
non-contra-rotating blades. Additionally, the contra-rotating blade
sets 109, 110 may produce minimal to zero net torque on the vehicle
100. This feature helps to prevent inadvertent contact between the
guideway 302 and the levitation system 303 when used, should torque
be introduced into the system, especially at vehicle 100 startup.
In other embodiments, the propeller arrangement 105 may have a
single set of blades. In this embodiment, the propeller arrangement
105 may be a single rotating propeller; the advantage of this
embodiment is that the propeller arrangement 105 produces less
noise than the contra-rotating double blade-set propellers, has a
simpler drive mechanism than contra-rotating propellers, and is
less expensive.
[0063] Another possible propeller arrangement may include
contra-rotating, tandem propellers, with one contra-rotating
propeller assembly located at each end of the vehicle. The
propeller arrangement according to this embodiment, similar to the
contra-rotating propeller discussed above, helps to reduce energy
losses and is more efficient than propellers having a single set of
non-contra-rotating blades. Additionally, the contra-rotating,
tandem propeller helps the vehicle achieve higher speeds as
compared to the vehicle equipped with either a single set of
non-contra-rotating propellers or a single contra-rotating
propeller located at only one end of the vehicle.
[0064] The blades of each of the first and second blade set 109,
110 are connected to the body of the vehicle 100 at the tip region
101 of the body 102. The blade arrangements 109, 110 may be
provided with more or fewer blades, and in some instances more
blades (e.g., 7 instead of the 6 shown in FIG. 2) may facilitate an
increase in propeller efficiency and thrust or result in less
noise. Similarly, in some embodiments, the wider the blades 109,
110 and the more uniform the thrust distribution on the blades 109,
110, the higher the efficiency of the propeller arrangement 105.
Similarly, the blades 109, 110 may be shaped in a swept-back
configuration as in a supersonic wing, and have an angular shape
with a sharp leading edge, which together allow a higher vehicle
speed at which shock waves from the propeller become limiting.
[0065] In addition to driving or propelling the vehicle 100, the
propeller blades 109, 110 may be used to brake and stop the vehicle
100 or reverse the direction of the vehicle 100. When used for
braking of the vehicle, pitch of the blades may be reversed so that
the propellers are running as turbines whose electric power is
dissipated in a resistor or used to regenerate rechargeable
batteries. That is, braking of the vehicle 100 may be accomplished
by increasing the pitch of the propeller blades 109, 110 beyond the
feathered position. Alternatively, the vehicle could use a "gas
brake" wherein one or more plate-like structures are extended to
increase the aerodynamic drag on the vehicle, or the vehicle could
use an eddy-current brake wherein eddy currents are induced into a
metal structure along the rail, or into the rail itself, by one or
more electromagnets carried on the vehicle.
[0066] Reversal of the vehicle may involve rotation of the blades
109, 110 by 180.degree. around their radial axes, followed by
reversal of rotational direction of the propellers 109, 110. Once
the vehicle 100 is slowed (braked) by changing the propeller pitch,
as described above, the method of reversing vehicle 100 may include
rotation of the blades 109, 110 by 180.degree. around their radial
axes, followed by reversal of rotational direction of the
propellers. This feature allows the vehicle 100 to levitate within
the tube 406 and still be able to stop without relying on friction
brakes, which can produce significant amounts of heat and suffer
wear. However, friction brakes, or an equivalent mechanical form of
braking, may be used to hold the vehicle 100 in place on the
guideway once it has been braked and stopped by the propellers 109,
110. For instance, the vehicle 100 may use friction brakes,
magnets, or the like placed on the levitation system 303 or on the
bottom of the vehicle 100, to stop the vehicle 100. Similarly, the
vehicle 100 may use a second propeller located at the rear of the
vehicle 100, which propeller set is normally configured to provide
propulsion supplementing the front propulsion system but may
separately be used for braking. In any case, the vehicle 100 may be
stopped or put in reverse in any manner.
[0067] The motor 1004 drives the propeller arrangement 105. The
motor 1004 is powered by a fuel-cell stack 1012. It is possible to
use other power sources or supplement the fuel-cell stack 1012
power output. However, in the implementation discussed herein, the
fuel-cell stack 1012 synergistically "breathes" the hydrogen 407
(or other gas) within the tube 406 as its fuel source. The motor
1004 may be any device capable of using energy or electricity to
drive the propeller 104. For example, the motor can be an
alternating-current (AC) motor, a direct current (DC) motor, a
hydraulic motor, and the like. In one embodiment, the motor 1004 is
an AC induction motor.
[0068] When the vehicle operates in a tube filled with hydrogen, to
collect hydrogen gas 407 (or other gas) from the tube 406 for use
in the fuel cells of the vehicle 100, an intake scoop 1006 is
provided on the vehicle 100 near the propeller arrangement 105. The
intake scoop 1006 collects hydrogen 407 from the tube 406 and
directs it into the fuel-cell stack 1012 in a flow-through manner.
To exhaust excess hydrogen from the vehicle 100, an exhaust scoop
1007 is provided, in one embodiment, on the diametrically opposite
side of the vehicle 100. The diametric disposition of scoops 1006,
1007 is illustrative and not intended to be limiting, and any angle
formed between scoops 1006, 1007 and the vehicle centerline 112 may
be used. The exhaust scoop 1007 releases excess hydrogen 407 not
consumed by the fuel-cell stack 1012 from the vehicle 100 to the
tube 406. Each scoop may be rotated by 180.degree. when the vehicle
100 reverses direction of travel. That is, in order to maintain
hydrogen flow in a fixed direction through the fuel-cell stacks, if
scoop 1006 is the intake scoop in one direction, it may be rotated
by 180.degree. when the vehicle 100 reverses direction, and thereby
it will continue to be the intake scoop. It will continue to be the
intake scoop because the direction of the hydrogen airstream
relative to the vehicle 100 has changed by 180.degree..
[0069] The intake scoop 1006 and the exhaust scoop 1007 are
oriented in opposite directions. The intake scoop 1006 faces the
front of the advancing vehicle and hence hydrogen 407 is rammed
into the scoop and delivered to the fuel-cell stacks. The exhaust
scoop 1007 faces toward the rear of the advancing vehicle 100 and
hence the relative motion of the vehicle 100 and hydrogen 407 tend
to suck the hydrogen flowing through the stacks 1012 into tube 406.
The effects of ramming and sucking work together to distribute
hydrogen through the fuel-cell system in a passive manner. The
intake scoop 1006 and the exhaust scoop 1007 may be constructed out
of suitable material for withstanding the high gas pressure of high
speeds. The intake scoop 1006 and the exhaust scoop 1007 may be any
shape capable of receiving and dispersing hydrogen 407 to and from
the tube 406. In some embodiments, the intake 1006 and the exhaust
1007 may be shaped as open rectangular vents. For the combined
ramming and sucking effects to work in each direction of vehicle
100 travel, the intake 1006 and the exhaust 1007 are designed to
rotate by 180.degree. when the vehicle 100 changes direction from
forward to reverse.
[0070] A fan 1008 assists the intake 1006 in pulling hydrogen 407
from the tube 406. For example, when the vehicle 100 is not moving
or is moving slowly, the intake 1006 may not be able to passively
breathe as much hydrogen 407 as is necessary to operate the fuel
cells 1012. In these instances, the fan 1008 turns on and pulls
hydrogen 407 through the intake 1006 using suction or other means.
The fan 1008 is located in a duct system 1010 that channels
hydrogen from the intake 1006 to the fuel-cell stack 1012. The fan
1008 may be an axial fan, a squirrel-cage fan, a pump, or the like.
In some embodiments, the fan 1008 may only operate when the vehicle
100 is traveling at low speeds or is stopped. In other embodiments,
the fan 1008 may operate at all vehicle 100 speeds, such that the
hydrogen 407 intake flow through scoop 1006 is maximized or
otherwise controlled.
[0071] The duct system 1010 transports gas 407 from the intake 1006
to the fuel cells 1012 and from the fuel cells 1012 to the exhaust
1007. The duct system 1010 may involve piping, tubing, or any
suitable conduit that transports the hydrogen 407 from within the
tube 406, to within the vehicle 100 and then directs the unused or
excess hydrogen 407 back into the tube 406. However, the duct
system 1010 may be omitted, for instance, the intake 1006 and
exhaust 1007 may directly connect to the fuel cells 1012 and to the
tube 406 environment, without the additional piping or tubing.
[0072] As discussed above with respect to the motor 1004, the
fuel-cell stack 1012 supplies power to drive the motor 1004. A fuel
cell may use hydrogen and oxygen to generate electricity. The fuel
cells in stack 1012 receive hydrogen 407 from the tube 406 via the
intake 1006 and receive oxygen from an oxidant storage container
1014 onboard the vehicle. In some embodiments the fuel cells 1012
are an acid-electrolyte proton-exchange membrane type, wherein
liquid oxygen provides oxygen (the oxidant) to the fuel cells, and
the fuel-cells' fuel, hydrogen (the reductant or reducer), is
breathed from the tube 406. In these embodiments, hydrogen flows
through the fuel-cell stacks, in the manner described above by the
action of the scoops 1006, 1007, and oxygen is dead-ended. The
fuel-cell stack 1012 produces electricity when hydrogen at the
anode gives up electrons to an external circuit plus positively
charged hydrogen ions that move through an electrolyte (not
illustrated) within the fuel cells of stack 1012 and combine with
the oxygen to produce water at the cathode. As the oxygen is
dead-ended, water is produced at the cathode as a waste product of
the electricity production of the fuel cells 1012. This embodiment
allows the water produced by the fuel-cell stack 1012 to be stored
onboard in a waste storage container 1024, versus being exhausted
into the tube 406. Excess hydrogen gas that is not used in the
energy conversion process is expelled back into the tube 406 via
the exhaust scoop 1007. However, the fuel cells of stack 1012 may
be any fuel-cell type that uses hydrogen and oxygen as fuel
sources. More generally, the fuel cells may use any gaseous fuel
that provides the atmosphere within tube 406, for example, methane.
Examples of fuel-cell types are proton-exchange membrane fuel
cells, alkaline fuel cells, phosphoric acid fuel cells, molten
carbonate fuel cells, solid oxide fuel cells, and the like. There
may be any number of fuel cells within stack 1012. For instance, to
increase the power of the vehicle, more fuel cells may be added to
stack 1012, or the size of the fuel-cell electrodes in stack 1012
may be increased, depending on the power requirements of the
vehicle 100.
[0073] The oxidant storage tank 1014 holds the oxidant required to
operate the fuel cells of stack 1012. The oxidant storage tank 1014
may be any type of storage device suitable for storage of a
compressed gas, a cryogenic liquid, a chemical oxygen source such
as hydrogen peroxide, or the like. In one embodiment, the fuel
storage tank 1014 holds liquid oxygen in a vacuum-insulated storage
tank; however, the oxidant storage tank 1014 may be used to hold
oxygen gas, chemical precursors of oxygen, or other desired oxidant
capable of reacting with hydrogen. The fuel cells 1012 combine
oxidant from the oxidant storage tank 1014 with the hydrogen 407
collected from the tube 406 via the intake scoop 1006.
[0074] A water separator 1016 may separate water from cathodic
oxygen and remove traces of water from the hydrogen exit stream
through scoop 1007. For instance, in some embodiments, the
separator 1016 separates water from cathodic oxygen and runs the
separated water to storage tank 1024. The separator 1016 may also
function to condense unwanted materials and thereby prevent them
from entering the tube 1006. For instance, the separator 1016 may
also remove traces of water from the hydrogen exiting the fuel-cell
stack 1012. One embodiment of the separator is also used as an
evaporator to convert liquid oxygen stored onboard to gaseous
oxygen used by the fuel cells; the cold liquid oxygen on one side
of a heat-exchange surface causes freezing of the impurities, for
example, water, on the other side of the heat-exchange surface.
[0075] A set of coolant lines 1030 supply waste heat from the fuel
cells and other components to the liquid-oxygen evaporator within
separator 1016 and then expel the excess heat to the hydrogen 407
via a liquid-gas heat exchanger 1020. The source of waste heat is
primarily from the fuel cells, the propulsion motor(s), and the
power electronics.
[0076] A heat exchanger 1020 is connected to the coolant lines 1030
and may be used to reject excess heat from the fuel cells, the
propulsion motor(s), and the power electronics to the hydrogen
atmosphere in the tube 406. Because of the high thermal
conductivity of hydrogen (seven times greater than air), the heat
exchanger in one embodiment is simply a thin shell on the outside
of the body 102. In contrast, liquid-air heat exchangers, for
example, the radiator of an automobile, require a greater surface
area than this embodiment because of the seven-fold lower thermal
conductivity of air versus hydrogen.
[0077] The power electronics subsystem 1022 changes and controls
the voltage of the DC output from the fuel cells 1012 to the
voltage, DC or AC, as required by the propulsion motor 1004,
vehicle communications systems, vehicle control systems,
passenger-car HVAC and lighting systems, and all other electrical
components on the vehicle 100.
[0078] Waste water produced from the reaction of hydrogen and
oxygen within the fuel cells is directed towards a water storage
container 1024. The water storage container 1024 is connected to
the separator 1016. The waste storage container 1024 may be
constructed out of any type of material suitable to store water,
for instance, plastic, metal, or the like. Waste water storage, in
one embodiment, is provided by a horizontally oriented cylinder and
may have a volume of about 1500 liters. However, depending on the
desired trip length of the vehicle 100, the size of the vehicle
100, the type of fuel cells used, etc., the waste storage container
1024 may be designed to hold more or less volume.
[0079] The levitation system 303 according to the embodiment shown
in FIG. 2 utilizes aerostatic gas-bearings 1028 that may
collectively be comprised of smaller bearing units such as
segments, as described below. Hydrogen gas is pumped through porous
gas bearings 1028 and the flow of hydrogen, or other gases such as
methane or helium, between the bearing surface and the vee-way
surface levitates the vehicle 100. Thus, the vehicle 100 levitates
on a low-friction fluid film provided by gas-bearings 1028.
[0080] A coupler 1026 is used to connect multiple vehicles
together, as well as connect the vehicle 100 to passenger or cargo
cars. For instance, as illustrated in FIG. 3, the vehicle 100 may
act as a locomotive and pull other cars. In the implementation
shown herein, the locomotive tube vehicle is conically shaped with
the propeller arrangement 105 located at a tip area 101 of the body
102, and the coupler 1026 is positioned at a planar area 1032 at
the rear of the vehicle 100, opposite the tip 101. A car 308, as
shown in FIG. 3, is cylindrical with a circumference matching that
of the area of the locomotive adjacent to the planar area. The car
308 has generally planar front and rear areas to minimize the gap
301 between car 308 and locomotive 100 and thereby reduce
aerodynamic drag. The gap 301 may furthermore be covered by a thin
flexible seal to further reduce aerodynamic drag. In these
embodiments, for a consist of two locomotives (one front and one
rear) and one or more cars 308, the coupler 1026 attaches the
locomotives 100 to one or more passenger cars 308, and passenger
cars to each other, allowing the vehicle 100 to pull the cars 308.
The consist (also referred to as a trainset) 100, 308 of FIG. 3,
that is, the assembly of locomotives and train cars, is
multi-articulated, and articulation allows swiveling of adjacent
segments of the consist (or trainset) in three-dimensional space.
Relative motion in three dimensions allows the trainset to conform
to the vee-way as the vee-way twists in curves and bows at the top
and bottom of hills. The vehicle 100 may be connected via the
coupler 1026 to a number of different passenger cars and a second
locomotive vehicle may be attached at the end of the passenger
cars. The coupler 1026 in some embodiments may be a ball and socket
coupling, but in other embodiments may be a hook and latch, buffers
and chains, link and pin, and the like.
[0081] FIGS. 11A and 11B illustrate a side-view and a bottom view,
respectively, of the vehicle 100, emphasizing the gas-bearing
levitation system 1100, which includes the gas bearings 1028. The
levitation system 1100 may include a front set of bearing segments
1102, 1103 and a back set of segments 1104, 1105. The segments are
positioned longitudinally along the length of the body 102 of the
vehicle 100. The segments may twist, tilt, or rotate, possibly
under the control of servo mechanisms that sense the shape of the
vee-way, so as to allow the gap between a segment and the vee-way
to be controlled. The suspension system 1100 may also include a
fairing 1106 that partially covers the segments 1102-1105 and
thereby reduces the aerodynamic drag on the gas bearings 1028. The
fairing 1106 is attached to the bottom of the vehicle 100, and has
generally planar sides 1108 and a planar back portion 1109, but
tapers to a beak-like point 1110 oriented to the front of the
vehicle 100 (the direction of travel). Below the planar sides 1108,
a surface of the fairing 1106 also defines a downwardly angled
V-shaped area, which is contoured to match a V-shaped surface on
the guideway 302. For example, the guideway 302 may be shaped as a
vee-way, and the fairing 1106 may then be shaped as a "V", to
conform to the shape of the vee-way. Aerostatic bearing segments
1103 and 1105 are separated on the face of the lower V-shaped
portion of the fairing 1106, and the opposing segments 1102 and
1104 are supported on the opposing face of the V-shaped portion of
the fairing 1106. The levitation system 1100 may additionally
include a strut 1107. The strut 1107 supports the body 102 of the
vehicle 100 above the levitation system 1100. The strut 1107 is
disposed between the body 102 of the vehicle and the fairing
1106.
[0082] The segments 1102-1105 include four segments for each
bearing surface, but any number of segments may be used. The
segments 1102-1105 are included both on vehicles acting as
locomotives, as well as passenger and cargo cars. Referring now to
FIG. 11B, the suspension segments 1102-1105 may be grouped into
sections, a first segment 1102, a second segment 1103, a third
segment 1104 and a fourth segment 1105, not necessarily numbered in
this description as they occur along the length of the vehicle 100.
The bearing segments 1102-1105 may be aerostatic gas bearings or
the magnets of the magnetic-levitation embodiment described below.
In the aerostatic gas-bearing embodiment, the segments 1102-1105
have multiple holes or are made of a porous material. For example,
the segments 1102-1105 may be constructed of porous graphite or of
metal that may be sintered or contain holes, allowing the flow of
fluid between the segment and the upper V-shaped surface of the
vee-way. Fluid (gas or liquid) is pressurized and forced out of the
holes of the segments 1102-1105, creating a low-friction fluid film
between the bearing segments 1102-1105 and the top of the vee-way
(guideway) 302, effectively levitating the vehicle 100 above the
bottom portion of the tube 406 on a thin film of gas or liquid. If
the suspension system 1100 has aerostatic gas bearings, the gas 407
used to suspend the vehicle 100 may be hydrogen. Likewise, if the
gas 407 is an alternative gas, for example, methane or helium, this
gas will likewise be the operating fluid of the aerostatic gas
bearings. The hydrogen or other gas 407 may be provided to the
gas-bearing levitation system 1100 by the intake 1006, and
pressurized via a gas pump carried onboard vehicle 100 powered by
the fuel cells. In this embodiment, the atmosphere of the tube 406
is not polluted by having materials other than the desired tube
atmosphere enter the tube, as the gas 407 is taken from the tube
406 and then distributed back into the tube 406 as it creates a
fluid film to levitate the vehicle 100. In other embodiments,
hydrostatic (water) bearings may be used as the fluid in the
levitation system 1100. In this embodiment, liquid is forced out
through the segments 1102-1105 creating the suspension layer for
the vehicle 100. The liquid water is then collected in a trough
running down the center of the tube 406. If water is the levitating
fluid, the hydrogen or other gas comprising the atmosphere 407 may
be saturated with water vapor. In the case of magnetic levitation,
the segments 1102-1105 represent permanent magnets, superconducting
magnets, AC electromagnets, or the like.
[0083] FIG. 12 illustrates a perspective view of some of the
functional components of the vehicle 100 shown in FIG. 1 according
to some other aspects of the current disclosure. In the specific
example shown in FIG. 12, the vehicle includes contra-rotating
tandem propellers, with one contra-rotating propeller assembly
located at each end of the vehicle. The propeller arrangement
according to this embodiment, similar to the contra-rotating
propeller discussed above, helps to reduce energy losses and is
more efficient than propellers having a single set of
non-contra-rotating blades. Additionally, the contra-rotating,
tandem propeller helps the vehicle achieve higher speeds as
compared to the vehicle equipped with either a single set of
non-contra-rotating propellers or a single contra-rotating
propeller located at only one end of the vehicle. As shown in the
figure, each propeller arrangement 105 includes a first set of
propeller blades 109 and a second set of propeller blades 110 that
are configured to rotate about a common axis 112 defined generally
along the longitudinal centerline of the vehicle 100. In the
example shown, the first and second sets (or more than two sets) of
blades include five blades each concentrically and evenly spaced
about the common axis, although the number of blades provided in
the first and second sets of blades can be optimized for the
atmosphere in which they are to operate as discussed above, and the
number of blades can be different in the two sets, e.g., six in the
first set and five in the second set. Each set of blades is coupled
with a common propulsion motor 1202 that drives each set of blades
in opposing directions making the propeller function as a contra
rotating propeller. Alternatively, each row of blades (e.g., five
blades in vehicle 100) could have its own propulsion motor. The
propeller arrangement is further coupled to a propeller variable
pitch mechanism 1204 that provides control of the pitch of the
blades. In one implementation, the variable-pitch mechanism is not
housed within the propeller hub but in the vehicle body. As shown
in more detail in FIG. 13, the variable pitch mechanism 1204
includes contra-rotation gears 1302, a worm-gear servo motor 1304
and a double worm-gear drive 1306 that together with a blade twist
mechanism 1308 couple to each propeller blade function to control
propeller pitch.
[0084] Referring still to FIG. 12, the vehicle 100 includes the
wheel system 103 that may include one or more wheels 107
longitudinally aligned along the bottom portion of the vehicle. As
shown in FIG. 14 the wheels 107 may be rimmed wheels 1402 with an
aerostatic bearing spindle 1404 and a bearing housing 106. For the
example vehicle having dimensions discussed above, the wheels may
have a diameter of 0.08 meter. In order to protect the wheels and
to reduce the aerodynamic drag, the wheel system may also include a
fairing 108 that partially covers the wheels. The fairing 108 is
attached to the bottom of the vehicle 100, and has generally planar
sides, but tapers to a beak-like aerodynamic point oriented to the
front, bottom, and rear of the vehicle 100.
[0085] The vehicle 100 may also include ailerons 111 toward the
middle of the vehicle that function to balance the vehicle when the
vehicle is operated above a certain minimum speed (V.sub.min). As
shown in more detail in FIG. 15, the ailerons 111 are part of an
aileron assembly 1500 that includes a pair of ailerons located at
each end of an aileron shaft 1502. The ailerons, driven by a servo
motor and gear drive 1504 coupled to a bevel gear 1506, twist in
opposite directions. The aileron assembly may also include a sensor
or a set of sensors that measure an angle of inclination of the
vehicle. Information from the sensor(s) can be used to control the
ailerons through a feedback mechanism, and thereby keep the vehicle
close to upright.
[0086] The vehicle 100 may further include a landing gear assembly
1206 that allows for the vehicle to take off and to stop and to be
held upright when the speed of the vehicle falls below a minimum
speed (V.sub.min) or when the vehicle is at rest. The vehicle
includes longitudinally arranged wheels that may not balance the
vehicle at slow speeds or at rest; therefore the vehicle includes
landing gear to allow the vehicle to reach the proper speed for the
ailerons to balance the vehicle, after which the landing gear may
be retracted. In particular, the landing gear is designed to grasp
two faces of the rail to steady the vehicle. As shown in more
detail in FIG. 16, the landing gear 1206 includes a landing-gear
leg 1602, coupled to a servo motor with a gear drive 1606, which
includes a pad ("slipper") of low-friction material such as Nylon,
Teflon, or similar material, or includes small wheels, that
together press against the face of the rail support structure and
hold the vehicle substantially vertical. When the vehicle 100 needs
to be brought to a stop, the landing gear, driven by the motor
1606, engages the rail or the rail support structure, thereby
stabilizing the vehicle on the rail. Alternatively, the landing
gear may be operated by hydraulic or pneumatic power. In one
particular implementation, the vehicle 100 may also include a
parking brake. The landing gear pads may also squeeze the faces of
the rail and thereby serve as a brake.
[0087] Although one or more of the embodiments disclosed herein may
be described in detail with reference to a particular vehicle, the
embodiments should not be interpreted or otherwise used as limiting
the scope of the disclosure, including the claims. In addition, one
skilled in the art will understand that the following description
has broad application. For example, while embodiments disclosed
herein may focus on certain vehicles, such as a propeller-driven
vehicle, it should be appreciated that the concepts disclosed
herein equally apply to other transportation methods. For example,
the concepts disclosed herein may be employed in automobiles,
trains, and aircraft. In addition, it should be appreciated that
the concepts disclosed herein may equally apply to
non-transportation related items, such as manufacturing and
scientific laboratory apparatus. Furthermore, while embodiments
disclosed herein may focus on a gas-filled operating atmosphere,
the concepts disclosed herein equally apply to other operating
atmospheres, such as air. Accordingly, the discussion of any
embodiment is meant only to be exemplary and is not intended to
suggest that the scope of the disclosure, including the claims, is
limited to these embodiments.
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