Provisional Patent Application of

Douglas J. Amick

ABSTRACT
The tethered wind turbine uses an aerodynamic, flow-concentrating shape and lighter-than-air
construction utilizing a lifting gas and an electrically conductive tether fixed to ground to reap
energy from the wind at low or high altitude. The design has no need for the large, expensive,
bulky and unsightly tower structures, pivoting nacelles, or gearboxes presently used in
conventional horizontal axis windmills. The tethered wind turbine of this invention easily and
passively floats aloft downwind to a direction and position that is aligned with the wind. The
invention uses sensors and control modules to fly gracefully at an optimal altitude in most wind
regimes and also to ascend/descend when appropriate to seek shelter from extreme weather
conditions. Ideally, the tethered wind turbine of this invention would utilize carbon nanotube
materials in its tether for both structural and conductive purposes. The ring-wing section profile
in the preferred embodiment of this invention optimally would have a very low coefficient of
drag. A major benefit of this invention is potentially much lower cost per installed kilowatt
capacity and a lower operating cost per kilowatt hour delivered to the end user.

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For

TITLE: TETHERED WIND TURBINE

CROSS-REFERENCE TO RELATED APPLICATIONS: None.

FEDERALLY SPONSORED RESEARCH: None.

SEQUENCE LISTING: None.

BACKGROUND

This invention called “Tethered Wind Turbine” relates to wind powered devices that generate

energy from the wind, specifically to windmills that are deployed at or above ground or sea level.

However, in another embodiment, this invention could also be used to generate energy from

undersea water currents, being more appropriately called a tethered underwater current turbine

energy generator.

Windmills in recent years have become more effective and competitive with other energy

sources, but most still remain very expensive to install and maintain. As a result, their overall

Patent Application of Douglas J. Amick for

“Tethered Wind Turbine” continued

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cost per installed kilowatt hour is still high enough that they are only marginally deployed and

they contribute only a small amount to the electrical grid. The primary method modern

windmills use today is a horizontally-mounted, large diameter, three-bladed propeller that rotates

at low revolutions-per-minute over a very large swept area. The higher the rotational axis of the

propeller can be mounted, the better. The natural speed of the wind increases proportionally

with an increase in the height above the ground. Conventional windmills have very tall and very

strong tower structures. Typically they have a tubular steel tower that is mounted to a deep

below ground cement base. The system has to be very carefully engineered and sited

appropriately for the surrounding terrain. The towers must maintain a central stairway or other

means to allow construction and operator access to the upper mechanicals. The tower must

accommodate the heavy gearbox, electrical turbine, and propeller assembly, as well as be strong

enough to withstand gale force winds, and potentially earthquakes. To make the system even

more complicated, the upper nacelle and gearbox/turbine housing must be able to pivot on a

vertical axis, so as to align the propeller correctly with the wind direction at any time during the

day or night. On many windmill systems the individual blades of the windmill are able to rotate

about their individual longitudinal axis, for pitch control. They can optimize the pitch of the

blades depending on the nominal wind speed conditions that are present at any one time at the

site. They can also change the pitch of the blade to “feather” the propeller if the nominal wind

speeds are too large. Occasionally the windmill is locked to prevent rotation, and the blades

feathered to prevent major damage to the machine in a storm. All of this pitch control

technology adds significantly to the cost of windmills. Another major problem with

conventional windmills is damage caused by lightning during thunderstorms. The blades can be

upwards of 300 feet in the air and are a good source for lightning to find a conductive path to the

ground. Some of the more recently designed windmills use a system of replaceable sacrificial

lightning conduction attractors that are built into each windmill propeller blade. They help

channel the lightning away from the vulnerable composite structure that comprises the blade

itself. The fact remains that one of the major causes of windmill downtime and maintenance

costs are caused by lightning damage. The size of many windmills is also a major problem for

inspection, diagnostics, and repair. Often workmen have to use ropes and climbing techniques to

perform maintenance on the massive machines. It is very expensive and dangerous. In recent

Patent Application of Douglas J. Amick for

“Tethered Wind Turbine” continued

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years workmen have fallen to their death trying to repair the blades. In conclusion, insofar as I

am aware, no current windmill provides competitively inexpensive energy generation without the

major defect of highly priced support tower construction and maintenance costs coupled with

high risk diagnosis and repair of the large windmill blades themselves.

SUMMARY

The invention, an improved windmill, is a special design that combines a lighter-than-air

structural design with an aerodynamic shape that concentrates the wind’s forces through a

relatively-higher-RPM yet smaller-diameter turbine generator, thus eliminating the need for a

fixed tower. The lighter-than-air machine is tethered to the ground and can therefore freely align

itself optimally with the direction of the prevailing wind automatically and with no loss in

efficiency. The tether also provides the conductive path for the wind turbine’s electrical energy

to travel down to the base station where it can enter the grid or be used locally. In one

embodiment, the system employs ultra-low weight onboard weather diagnostic computer

technology to be able to smartly know when to remain aloft, and when to robotically be retracted

and returned to the base shelter to wait-out a potentially destructive storm. This feature would

effectively eliminate the lightning damage problem of current windmills.

Several advantages of the invention are to provide an improved windmill, to provide a means of

reducing the cost of wind generated electrical energy, to provide a wind generator with much

reduced installation costs, to provide a wind generator with much reduced problems associated

with maintenance, bird and bat kills, and downtime due to lightning damage, and to provide a

low cost windmill design that is scaleable and that could be affordable and practical for

individual home owners and small community cooperatives, as well as an attractive alternative to

fossil fuels for large energy companies to use in their electric grid operations. An additional

objective would be to produce an embodiment of the invention that would perform well

underwater as a lighter-than-water, tethered, sea-current turbine generator.

Patent Application of Douglas J. Amick for

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DRAWINGS

FIG. 1 is a perspective left-side view of a tethered wind turbine constructed in accordance with

the invention, showing primarily the left half of the funnel-shaped wind turbine.

FIG. 2 is a perspective right-side view of the tethered wind turbine of FIG. 1.

FIG. 3 is a longitudinal cross-sectional view of the wind turbine of FIGS. 1 and 2, showing the

fluid flow, internal turbine parts, and control module.

FIG. 4 is a perspective front view of the wind turbine of FIGS. 1 and 2, showing an embodiment

that uses a rear mounted vertical wing stabilizer.

FIG. 5 is a perspective left-side view of the wind turbine of FIGS. 1 and 2, showing an

embodiment of the invention that uses one combination of rear wing stabilizers and forward

mounted lifting wings to improve stability and performance.

FIG. 6A is a perspective left-side view of the tethered wind turbine of FIGS. 1 and 2 that shows

it in operation at a medium height, being tethered to the base structure on the ground.

FIG. 6B is a perspective left-side cutaway view of the invention of FIGS. 1 and 2 showing the

typical base structure with the hanger doors open and the tethered wind turbine retracted to the

top of the main pulley.

FIG. 6C is a perspective left-side cutaway view of the invention showing the typical base

structure with the hanger doors closed and the tethered wind turbine fully captured for ground

storage.

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FIG. 6D is a perspective left-side detail view of the tether component of the invention of FIGS. 1

and 2 showing its typical construction.

FIG. 7A, 7B, 7C are longitudinal cross-sectional views of the wind turbine of FIGS. 1 and 2,

showing the harness pitch retractor at various adjustments, and the resultant aerodynamic pitch

angle of the tethered wind turbine invention.

FIG. 8A is a perspective left-side view of the tethered wind turbine of FIGS. 1 and 2 that shows

how in one embodiment of the invention a simple tubular tail boom (110) could be used to

mount rear wing surfaces such as vertical stabilizer (52) and horizontal stabilizer (56).

FIG. 8B is a longitudinal cross-sectional view of the wind turbine of FIGS. 1 and 2, showing

how the fluted tail section (112) could be built to allow outlet air (114) to exit through slots in

the tail boom section itself.

FIG. 9A, 9B, 9C, 9D are longitudinal cross-sectional views of the wind turbine of FIGS. 1 and 2,

showing how potentially many different section shapes of the gas inflated structure could be used

without materially diverging from the scope of this invention.

DETAILED DESCRIPTION

FIG. 1 is a perspective view taken from the left side from the ground standing upwind of the

tethered wind turbine constructed in accordance with the invention. The funnel shaped front

inlet (14) is shaped with an annulus (12) that directs the oncoming apparent wind into the

interior. A lower portion of the invention has attachment brackets (18) that are used to connect

the harness (20) and tether (22) to the main body casing (10). Large quantities of wind pass

through the inlet (14), the turbine area of the tethered wind turbine, finally exiting the invention

through the outlet (16). The energy harvesting invention is lighter than air and thus remains aloft

in all wind conditions.

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FIG. 2 is a perspective view taken from the right side from the ground standing upwind of the

tethered wind turbine constructed in accordance with the invention. The wind entering the inlet

(14) passes over the impeller rotor (26). Energy extraction occurs here at the turbine (24) as is

shown near the narrowest part of the hourglass-like internal shape.

FIG. 3 is a longitudinal cross sectional view of the tethered wind turbine drawn in accordance

with the invention. Both the interior and exterior surface profiles, as shown in this view, are

designed to be as aerodynamically efficient as is feasible. The ring-wing section profile in the

preferred embodiment of this invention optimally would have a very low coefficient of drag.

The majority of the physical aerodynamic shape of the tethered wind turbine is filled with a

lifting gas (40), such as helium. This lifting gas is contained within sealed polymeric inflated

structures (42) made from polymers such as aluminized polyester film, polyethylene, or other

film. The entire tethered wind turbine may also use an exterior lightweight flexible or

lightweight rigid exterior skin to act as a shape structure and to protect the tethered wind turbine

from the deteriorating effects of ultraviolet solar radiation. One flexible film that would work

well ideal for this purpose in this invention is Tedlar (DuPont) film. A rigid material for the

exterior could be composite material such as carbon fiber matrix or carbon nanotubes matrix.

The tethered wind turbine has an intake flow concentrator nozzle (32) just to the interior of the

leading edge annulus (12). There is a flow expansion nozzle (34) at the outlet (16) of the

invention. Between the concentrator and expansion nozzles there is a turbine (24) energized

electric generator (28). It is also envisioned, though not shown, that the turbine could

mechanically power other types of useable energy conversion and storage processes. One

concept envisioned in this invention is to directly convert the rotary motion into electricity and

use it onboard the tethered wind turbine to break water into hydrogen and oxygen, delivering the

valuable gases to the ground station through a multi-tubular tether, without any conductive wires

at all. The hydrogen could be stored in containment vessels on the ground and used for any

number of useful purposes. The structure of the tethered wind turbine is achieved by several

elements. The structural ribs (46) shown support the overall shape of the tethered wind turbine

and spread the loads of the turbine’s (24) and generator’s (28) mass into the craft in a stable

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manner. A light weight way to create the structure of the annulus (12) is shown, using an

inflated toroidal structure (44) that is filled with pressurized lifting gas (40). There are many

ways to achieve the necessary structure, and what is shown is meant to be an example of one

embodiment of the invention. The rotor impeller (26) is fitted with a streamlined impeller

nosecone (36) and impeller tail cone (38). The electric generator (28) can be any combination of

magnetic rotor or magnetic stator designs, either brush or brushless, and made of a variety of

materials. The preferred embodiment would use ultra-light-weight rare earth permanent magnets

with brushless DC components and windings that could possibly consist of carbon nanotube

hyper-conductive wires in place of copper to save even more weight. There are conductive

generator output wires (76) connecting the generator to the harness (20). The harness (20) is

secured to the tethered wind turbine at attachment brackets (18). Said attachment brackets (18)

could be hard mounted to the internal structure or physically attached or bonded to the outer skin

of the tethered wind turbine. The harness (20) can be rigidly attached, or mounted in such as was

as to allow controllable adjustments by mechanical servo-actuators. One embodiment of this

feature, a harness pitch adjustor (50), is shown and is a way to control the tethered wind turbine’s

angle of attack by lengthening or shortening the central member of a three point harness (20).

The control box (48) is the central brain for the onboard functionality of the tethered wind

turbine, controlling such as the harness pitch adjustor (50), the flight settings, the generator

loading, and any aerodynamic control surfaces, etc.

FIG. 4 is a perspective front view of the tethered wind turbine and shows an embodiment of the

invention that includes a vertical stabilizer (52) mounted at the top and to the rear of the craft.

The full front of the impeller rotor (26) and impeller nose cone (36) are visible and are described

visually as having 5 blades. Any number of impeller rotor (26) blades would be acceptable and

part of the intent of this invention. The outer casing (10) of the lighter-than-air is shown, as well

as the flow concentrator nozzle (32) and the annulus (12). Attachment brackets (18) secure the

harness (20) to the tethered wind turbine. The harness (20) is also shown secured to the tether

(22).

FIG. 5 is a perspective left side view of the tethered wind turbine. Showing an embodiment built

in accordance with the invention that uses a number of aerodynamic lifting and control surfaces

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to enhance the overall stability and performance of the wind energy extracting craft. Vertical

stabilizer (52) and horizontal stabilizers (56) act to further help keep the longitudinal axis of the

turbine (24) aligned with the apparent wind direction. These aerodynamic surfaces can be either

passive, or actively controlled with the use of stabilizer control surfaces (54). A wing (58) is

shown in this embodiment and can add additional lift to the tethered wind turbine to help it

remain at altitude even when the wind conditions attempt to blow the craft downwind and

downward. Wing control surfaces (60) are shown and help control roll as needed. These

control functions are envisioned to be fully controlled by the onboard control module (48).

FIG. 6A, 6B, and 6C show the tethered wind turbine as a system that is managed from a base

shelter structure (68). This base shelter structure (68) would be pre-built and carried to the site

or it could be built on the site. It would also be installed atop housing or buildings or concealed

below grade.

FIG. 6A is a left-side perspective with cutaway view of the tethered wind turbine and base

shelter structure (68) showing the invention in operation. The tethered wind turbine is flying at a

reasonable height above the ground, downwind of the base shelter structure (68), and is

constrained by the tether (22). The craft can be expected to float freely downwind in any

direction as a result of changes in true wind direction. The total airspace occupied by the

tethered wind turbine in the long term can be described as an inverted cone emanating from the

tether main attachment at the robotic control torus (72). The top diameter and half angle of the

inscribed cone is dependent on many variables such as the total buoyancy force of the invention,

maximum wind speed, amount of active flight controls used to maintain altitude, and active

tether extension/retraction deployed, and turbine generator load levels. To send the tethered

wind turbine to a higher or lower altitude while in flight, the tether (22) is unwound or wound-up

on the tether retractor reel (74) by the tether retractor mechanism (64). The cutaway view of the

base shelter structure (68) also shows a wish-bone launch arm (100) that swings up when the

tethered wind turbine is about to be launched and also swings down when the craft is retrieved

and tucked into the base shelter structure (68) for safe storage. This wish-bone launch arm (100)

mechanism may be shaped differently, such as having one leg instead of the wish-bone shape,

but all versions act as a lever to initially move the tethered wind turbine up out of the base shelter

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structure (68) or down within the its walls. The entire base shelter structure (68) sits on a site

pad (98).

FIG. 6B is a perspective cutaway view of the tethered wind turbine near the middle phase of the

launching process, or the retrieving for storage process. In the latter, the tethered wind turbine

has been pulled down out of the sky to a point where the harness (20) touches and interacts with

the robotic control torus (72). It shows the base shelter structure (68) with its hinged bay doors

(92) opened wide. The wish-bone launch arm (100) is in the upright position and the launch arm

actuators (102) are fully extended. Energizing the reel motor (66) causes the rotation of the

tether retraction reel (74), which is bi-directional in this embodiment of the invention. It rolls the

tether retraction reel (74) in one direction to wind-up (retract) the tether (22) and rotates the reel

in the opposite direction to unwind the tether (22), allowing the buoyant tethered wind turbine to

ascend upward into the airspace above. The control of the reel motor (66) is accomplished with

the logic that is built into the retractor control module (62). Also shown are the reel-to-power

box cables (78) that deliver electricity from the tether (22) to the power control/conditioning box

(70) where the electrical characteristics are tailored to meet desired output specifications of a

particular application. Power from the tethered wind turbine invention is delivered to the end use

through the output plug box (96).

FIG. 6C is a perspective left-side cutaway view of the entire tethered wind turbine and base

shelter structure (68) as a system that has been put into the storage mode where the inflated

casing (10) and other components are safe from excessive weather conditions such as lightning,

turbulent high winds, and wintry blizzards. In this state, the tether (22) is fully wound-up by the

tether retractor mechanism (64) onto the tether retractor reel (74). The wish-bone launch arm

(100) is in the lower position and the launch arm actuators (102) are fully retracted. The hinged

bay doors (92) are shown in the closed position. Meteorological sensors (104) on the base

shelter structure (68) monitor the air-space and keep the tethered wind turbine safely contained

until conditions are appropriate for launching in the future.

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FIG. 6D is a perspective detail view of the tether (22) itself. Within the outer casing (82) of the

tether are two critical components. They are the main tensile members (84) and the electrical

wires. Both the positive conductor wires (86) and negative conductor wires (88) are sheathed in

an insulation jacket that prevents short–circuiting and power drainage. Ideally, the main tensile

members (84) and the positive conductor wires (86) and negative conductor wires (88) would be

comprised of carbon nanotubes materials. Although these materials are not a requirement, the

use of carbon nanotubes materials in these components of the tether (22) would greatly enhance

the overall performance of the tethered wind turbine. That is because the tether (22) itself is a

parasitic weight loss acting against the tethered wind turbine’s buoyancy. Carbon nanotube

materials would make the tether (22) itself many times lighter and allow the tethered wind

turbine to fly much higher using less lifting gas (40). Electrical conductance of nanotube wires

would be many times higher than copper and would enhance overall efficiency greatly. In lieu

of carbon nanotubes materials, many other materials would also work well. Some examples are

copper core conductors, Spectra ™ fiber tensile members, Kevlar ™ fiber tensile members, or

polyester fiber tensile members.

FIG. 7A, 7B, and 7C are longitudinal cross-sectional views that show how pitch attitude of the

tethered wind turbine interacts with the apparent wind. In FIG. 7A the aerodynamic shape of the

inflated casing (10) is a ring-wing that is in a neutral angle of attack.

FIG. 7B shows the tethered wind turbine in a negative angle of attack (106). This maneuver is

accomplished by various means. Shown in this view the harness pitch adjustor (50) has let out

some length of the central line of the harness (20) causing the buoyant rear end of the inflated

casing (10) to be moved upward relative to the front end. In this state the flying ring wing is

going to descend. Another way to accomplish this negative angle of attack (106) is by using the

aerodynamic control surfaces of the horizontal stabilizer (56) or the wing control surface (60).

Conversely, as is shown in FIG. 7C, the harness pitch adjustor (50) has pulled in the central line

of the harness (20) causing the rear end of the inflated casing (10) to be moved downward

relative to the front end. This positive angle of attack (108) would cause the flying ring-wing

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tethered wind turbine to ascend, and allow the energy harvesting turbine system to increase

electrical output without as much loss of altitude. The higher loading of the turbine would mean

more total drag on the impeller rotor (26), and a tendency to descend. This could be balancedoff

or improved by calling for an even larger positive angle of attack (108) maneuver, and a

tendency to ascend.

FIG. 8A is a perspective left-side view of the tethered wind turbine showing how in one

embodiment of the invention a tubular tail boom (110) could be used to mount rear stabilizer

wing surfaces.

FIG. 8B is a longitudinal cross-sectional view of the wind turbine of FIGS. 1 and 2, showing

how the fluted tail section (112) could be built to allow outlet air (114) to exit through slots in

the tail boom section itself.

FIG. 9A shows a longitudinal cross-section of the wind turbine of FIGS. 1 and 2 that has a

elongated profile of the airfoil-shaped inflated casing (10) of the invention. FIG. 9B is a

potential shape that embraces a very short longitudinal airfoil profile of the inflated casing that

may be efficacious due to its large annulus (12) outside diameter relative to its turbine diameter

and air outlet (16) outside diameter. A prominent feature of this embodiment of the invention is

the large concentration ratio of the front inlet (14) flow concentrator nozzle (32). It appears the

concentration ratio is nearly 6 to 1, or higher. FIG. 9C shows almost the opposite inlet (14) style.

That is, it shows a very minor attempt to concentrate the wind at the inlet (14) flow concentrator

nozzle (32). The concentration ratio is nearly 1 to 1. FIG. 9D is a longitudinal cross-sectional

view of yet a different section shape and construction style. In this view the bulk of the lifting

gas (40) within the inflated casing (10) is located in the annulus (12) of the front inlet (14). The

remainder of the flow concentrator nozzle (32) in this embodiment is analogous to a wind-sock,

comprising a thin cone-shaped wall, whether of rigid or flexible material. As with a wind-sock,

the cone-shape become more pronounced by the wind flowing through it, All of these gas

inflated structures and many more could be designed and manufactured without materially or

significantly diverging from the scope of this invention.

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REFRENCE NUMERALS

10 inflated casing 12 annulus

14 inlet 16 outlet

18 attachment bracket 20 harness

22 tether 24 turbine

26 impeller rotor 28 electric generator

30 flowing fluid (air=wind, water=current) 32 flow concentrator

34 flow expansion nozzle 36 impeller rotor nose cone

38 impeller rotor tail cone 40 lifting gas

42 gas containment film 44 inflated toroid leading edge structure

46 internal structure 48 control module

50 harness pitch adjustor 52 vertical stabilizer

54 stabilizer control surface 56 horizontal stabilizer

58 wing 60 wing control surface

62 retractor control module 64 tether retractor mechanism

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66 reel motor 68 base shelter structure

70 power conditioner box 72 robotic controlled torus

74 tether winding reel 76 generator output wires

78 cables- reel to power control box 80 power output wires

82 outer casing 84 main tensile member

86 positive conductor wire 88 negative conductor wire

90 conductor wire insulation 92 hinged bay door

94 pulley system 96 output plug box

98 site pad 100 wishbone launch arm

102 launch arm actuators 104 meteorological analysis module

106 negative angle of attack 108 positive angle of attack

110 tubular tail boom 112 fluted tail section

114 outlet air

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OPERATION -- FIGs. 1, 2, 3, 4, 6, 7

FIG. 1 and FIG. 2 show the component of the tethered wind turbine invention that extracts

energy from wind currents. The inflated casing (10) is filled with helium or other lifting gas (40)

which makes the tethered wind turbine lighter than air. It also is shaped to scoop-up and

aerodynamically force large amounts of air to move through its own interior. The inflated casing

(10) is shaped like an airfoil wing that has been bent all the way around into a ring. At the front,

a funnel-shaped inlet (14) is surrounded with an annulus (12) at the leading edge. Together they

direct oncoming apparent wind into the central part of the ring-wing shape and into a smaller and

smaller opening. The wind then passes into the mouth of a rotary engine turbine (24), and finally

exits out the rear outlet (16) to return to the atmosphere.

NO NEED FOR A GEARBOX

The flow concentrator nozzle (32) gradually directs a large cross-sectional area of slowermoving

air to a smaller cross-sectional area, but higher velocity duct full of air. The laws of

aerodynamics say that air moving two times faster will carry eight times more energy. It is

apparent that an aerodynamically shaped device that can concentrate and accelerate the apparent

wind in a controlled manner will be very helpful in extracting energy from the wind. It is the

intent of this invention to use the flow concentrator nozzle (32) to make a large cross-sectional

area of slower-moving air to move through a smaller cross-sectional area at a higher velocity

through the turbine (24). This reduces the size of the physical hardware of the turbine (24) and

enables it to operate at a higher speed without the need for an up-ratio gear-box.

FIG. 3 shows that the turbine (24) is mounted centrally in the inflated casing (10). Air currents

can flow through it imparting energy to the turbine (24). The kinetic energy of a flowing fluid

(30), such as flowing wind, is converted into mechanical or electrical energy by causing the

blades of the impeller rotor (26) on the turbine (24) to rotate as it passes through. Output of

electrical energy harvested from the wind will be maximized when the wind throughput of the

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turbine is maximized. So every effort to streamline the interior surfaces is very important and

has been attempted to be shown in this preferred embodiment of the invention.

NO TOWER NEEDED

In most places on earth, the wind speed, and thus potential kinetic energy that could be harvested

is distributed in a gradient relative to ground, which could be described as increasing as one

moves to a higher altitude. Unlike most windmills currently available, the tethered wind turbine

of this invention operates without a tower. It simply does not need a tower. The preferred

embodiment of this invention uses a tether (22) to hold the inflated casing (10) and its turbine

(24) from sailing downwind with the force of available winds.

NO NACELLE NEEDED

The tethered wind turbine also has no need for a complicated rotating nacelle as is currently used

in the prior art to align properly with the direction of the true wind. The tethered wind turbine

has a unique ability to keep itself aligned properly to the wind automatically, even in changing

wind conditions. The inflated casing (10) will naturally drift to the most downwind position in

the sky, being restrained only by the tether (22). Just like the rudder on an airplane, the

invention directs itself in response to the changing wind’s direction.

FLYING THE TETHERED WIND TURBINE

FIG. 6A is a view looking downwind at the invention while it is operating. The tether (22) can

be let-out, or pulled-in, in a controlled way so as to position the inflated casing (10) in the most

favorable part of the natural wind velocity gradient. That is an altitude where the energy

extracted from the wind can be maximized.

As is shown in FIG. 6A, 6B, 6C the tethered wind turbine invention uses a base shelter structure

(68) to store the lighter-than-air device during inclement weather conditions, violent lightning,

periods of non-use, or for routine maintenance.

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FIG. 6A shows the tether (22) after it has been let out and the hinged bay doors (92) are closed.

The retractor control module (62) remains idle while the production of energy aloft in the turbine

(24) proceeds uninterrupted. The electrical power sent down the tether (22) travels through the

tether retractor mechanism (64), through the reel-to-power box cables (78), and into the power

conditioner box (70). At this stage the electricity is adjusted to a form that is compatible with the

end user electrical specifications and exits the system through the output plug box (96).

FIG. 6B shows the tethered wind turbine in the middle stage of launching or retracting. At this

stage the tether (22) is fully retracted, the wishbone launch arm (100) is in the upright position

and the hinged bay doors (92) are wide open. If in launching mode, the tether (22) would be let

out, the lighter-than-air inflated casing (10) would ascend slowly upward. If in the retracting

stage, the robotic control torus (72) would rotate the inflated casing (10) until the craft aligned

properly with the hinged bay doors (92) and then ready the system for final stage.

FIG. 6C shows the final stage of the tethered wind turbine when the inflated casing (10) is in the

completely stored mode. The wishbone launch arm (100) is in the lowered and horizontal

position resting underneath the inflated casing (10). The hinged bay doors (92) are closed and

the entire system is in standby mode.

CONTROLLING THE TETHERED WIND TURBINE

The preferred embodiment of the invention would have a smart logic circuitry built into it. The

control module (48), shown in FIG. 3, would make many decisions about when, where and how

to fly the tethered wind turbine. The onboard automatic-pilot feature of the control module (48)

would send control voltage signals to various aerodynamic control mechanisms to tune the flight

of the tethered wind turbine and thereby achieve a desired ascent trajectory and altitude.

At launch, there would be software programmed to fly the lighter-than-air tethered wind turbine

in a controlled, stable ascent. The tethered wind turbine’s ascension could be stable in zero-wind

conditions, or, even in rough and gusty wind conditions. This auto-pilot feature to maintain

Patent Application of Douglas J. Amick for

“Tethered Wind Turbine” continued

Page 17

straight and level flight during fluctuating of wind currents broadens the potential application to

many geographic locations that otherwise may not have been feasible.

CONTROLLING THE ANGLE OF ATTACK

Controlling the angle of attack of the inflated casing (10) is essential for flight control. By

controlling the angle of attack, the flying ring-wing-like tethered wind turbine would be able to

ascend on command to a predetermined altitude to achieve the best position in a given

environment. Once at the favorable altitude the tethered wind turbine would electronically loadup

the electrical generator (28) to increase electrical output.

As shown in FIG 7A, 7B, 7C one way this invention controls the angle of attack, the flight, and

ultimately the altitude, of the inflated casing (10) is to change the characteristics of its attachment

at the top of the tether (22). The attachment as shown in this embodiment of the invention

utilizes a three-point flexible harness (20). It has a method to adjust it as so as to change the

angle of attack and therefore the amount of lift on the inflated casing (10). It is the intent of this

invention to use the tether’s (22) harness pitch adjustor (50) device to vary the overall amount of

lift on the inflated casing (10) and thereby control the altitude it operates at. The harness pitch

adjustor (50) does this by extending or reeling-in the center rear harness tension member with a

servo motor mechanism. By adjusting the harness (20) attachment in the above described way

the overall angle of attack and hence the total lift of the ring-wing-like inflated casing (10) is

controlled. The desired altitude is either dialed into the control module (48) or determined

automatically by a software algorithm that takes into account several variables.

The benefit using the harness pitch adjustor (50) as envisioned in this invention to control angle

of attack of the inflated casing (10), a larger amount of electrical output would be achieved with

less loss of altitude. In the absence of any angle of attack flight controls such as the harness

pitch adjustor (50), higher loading of the turbine (24) would mean increased drag on the blades

of the impeller rotor (26), an increased total drag on the inflated casing (10), and a general

tendency for it to descend. This suboptimal condition could be improved by the use of the

harness pitch adjustor (50) of this invention, as described above.

Patent Application of Douglas J. Amick for

“Tethered Wind Turbine” continued

Page 18

There is one balance of forces that naturally occurs with the tethered wind turbine invention. If

winds escalate while the invention is operating, the overall forces increase on the inflated casing

(10). The natural reaction is for it to be drawn farther downwind and arc-tangentially lower

according to the radius struck by the length of tether extended at that time. Other things

remaining equal, the craft moves down to a lower altitude and hence a lower energy level in the

natural wind velocity gradient. This will reduce forces on the inflated casing (10) and result in a

convergence toward a natural equilibrium.

CONTROLLING THE GENERATOR

The control module (48) also sends control signals to the tethered wind turbine’s electric

generator (28) circuitry. For example, in favorable wind conditions the kinetic energy of the

moving air flow develops lift on the turbine (24) blades, turning the impeller rotor (26) and

electric generator (48). The only thing resisting the impeller rotor (26) turning motion is the

amount of load, or field resistance, that the electric generator (28) demands at a given point in

time. The load setting is a controllable variable that the control module (48) can monitor and

adjust. The tethered wind turbine utilizes the generator loading configuration to maximize power

output but at the same time retain adequate air stability and altitude. The more load levied on the

impeller rotor (26), the more overall wind drag will be developed on the craft. The total induced

drag on the lighter-than-air inflated casing (10) shows up as a tensile force on the tether (22)

along a vector in the downwind direction. The tension in the tether (22) is resisted by a mass

below. The control module (48) ideally should balance power output versus positional stability

and drag management. The control module uses electronic hardware and software as is

necessary to accomplish this goal.

CONTROL OF ELECTRICAL OUTPUT

The control module (48) also may condition the electricity that is output by the electric generator

(28). In may invert the voltage up to a higher voltage for the purpose of efficiently transferring

the generated power down the tether (22) to the base shelter structure (68) below. There would

be lower line losses experienced if the electricity traveling down the tether (22) were voltageadjusted

higher. The control module (48) would handle this function.

Patent Application of Douglas J. Amick for

“Tethered Wind Turbine” continued

Page 19

In summary, the control module (48) of the tethered wind turbine performs the following

functions:

surfaces

(50)

tether (22)

OPERATION of

ADDITIONAL EMBODIMENTS – FIG. 5

There are actually two ways this invention proposes to accomplish varying the angle of attack so

as to control the flight and altitude of the inflated casing (10). The first way to would be to use

automatic electrical control of the harness pitch adjustor (50) as described above.

In an additional embodiment of the invention, angle of attack would be controlled using

additional wings, stabilizers and other aerodynamic control surfaces. The net affect would be

increased control of total lift of the inflated casing (10) and an ability to control its altitude.

FIG. 5 shows one such additional embodiment of the tethered wind turbine invention using

aerodynamic control surfaces of many types. These include any and all types of active or

passive in-stream surfaces as are typically found on, but not limited to, conventional aircraft such

Patent Application of Douglas J. Amick for

“Tethered Wind Turbine” continued

Page 20

as a horizontal stabilizer (56), vertical stabilizer (52), stabilizer control surface (54), and any type

of wing (58), or wing control surface (60). It is unlikely that all of these would be necessary.

It is also the intent in this additional embodiment of the invention, for inflated casing (10) to use

its aerodynamic surfaces to soar to higher heights than would otherwise be possible in an effort

to counteract the craft’s downward altitude tendency caused by power extraction induced drag of

the turbine (24).

It should be noted that the inflated casing (10) of the tethered wind turbine could be secured to

ground through a less sophisticated tether system and it will still be a valuable energy extracting

machine in the sky. Or it could be outfitted to operate somewhat autonomously with its own

internal smart-chip controller and sophisticated controls for its harness pitch adjustor or its

aerodynamic wing control surfaces (60). The latter would probably come closer to maximizing

energy production efficiency, but would likely cost more to manufacture. It is a trade-off. The

tethered wind turbine invention as described in this document leaves room to cover both.

ADAPTING TO WEATHER

It is envisioned that an additional embodiment of the invention would have a micrometeorological

analysis module (104) onboard that could automatically obtain samples and or

use sensors to collect enough data in real time to be able to judge the likelihood of lightning or

other hazardous weather conditions. With knowledge of the meteorological facts, including but

not limited to, data on humidity, precipitation, temperature, atmospheric pressure, the presence

of ozone, or audio-visual signatures, the tethered wind turbine could be programmed to do

certain things. It would run the data through a decision formula that could prompt actions such

as immediately descending the inflated casing (10) to a safer altitude by reeling in the tether (22).

Other times in truly inclement weather, it could fully retract the invention to the safety of the

base shelter structure (68). This could all be done automatically and would prevent catastrophic

failures as otherwise could be experienced from such hazards as lightning strikes, tornado-like

wind currents, or destructive hail. The meteorological analysis module (104) could optionally be

located in the base shelter structure (68) or other place not onboard the inflated casing (10).

Patent Application of Douglas J. Amick for

“Tethered Wind Turbine” continued

Page 21

OPERATION of

ALTERNATIVE EMBODIMENTS FIGs. 8, 9

FIG. 8 A shows an alternative design of the tethered wind turbine that utilizes a very simple

boom and rear stabilizer arrangement. It represents a direct and simple method of construction.

FIG. 8B shows another more fanciful arrangement where the exit of air from the turbine (24) is

through a number of slots in the sidewalls of the tail structure.

FIG. 9A, 9B, 9C, and 9D show how the tethered wind turbine invention could still perform as

explained above but with different ring-wing cross-sectional profiles. FIG. 9A is an elongated

version of the preferred embodiment of this invention. FIG. 9B is a more exaggerated version

with the turbine (24) located very near to the air outlet (16) and the flow concentrator nozzle (32)

exhibiting a larger concentration of cross-sectional area ratio. FIG. 9C shows a profile that has

the turbine (24) located near the leading edge annulus (12) with a very small concentration of

cross-sectional area ratio. FIG. 9D is profile with most of the inflated part reserved to the front

annulus (12) itself.

ADVANTAGES of the TETHERED WIND TURBINE

It can be seen that the tethered wind turbine of this invention:

for an expensive and bulky up-ratio gearbox between the impeller rotor (26) and the

electric generator (28).

Patent Application of Douglas J. Amick for

“Tethered Wind Turbine” continued

Page 22

higher aloft than would otherwise be possible while extracting energy from the wind.

control trajectory, position, stability, altitude, generator loading levels and power output.

ultimately all the way into the base shelter structure (68) to avoid damage from lightning

or severe weather.

CLAIMS

(a) a buoyant, lighter-than-air device,

(b) an exterior skin of said lighter-than-air device with means to contain a lifting gas,

(c) a concentrating inlet of said exterior skin which is shaped aerodynamically to direct

naturally occurring air flows striking said lighter-than-air device in such a way as to

accelerate the velocity of said air flows within said concentrating inlet,

(d) a means, including a rotary turbine engine, for converting kinetic and inertial energy

of said accelerated air flows into useable energy,

(e) an outlet of said exterior skin of said lighter-than-air device which is shaped

aerodynamically to allow the said accelerated air flows to exit the device,

Patent Application of Douglas J. Amick for

“Tethered Wind Turbine” continued

Page 23

(f) means, including an electromechanical tether connected to said lighter-than-air device,

for said lighter-than-air device to be held against the force of the wind and the force of

said lighter-than-air device’s buoyant force,

(g) means, including an electromechanical tether connected to said lighter-than-air device,

for said useable energy to be transferred to the ground,

whereby, said lighter-than-air device with said means for converting kinetic and inertial

energy of said accelerated air flows into useable energy can ascend to an altitude

where wind conditions are more favorable, and utilize wind currents of a large crosssectional

area by concentrating them within said concentrating inlet shape into a

small-diameter, high-speed wind turbine within the center of said lighter-than-air

device that simultaneously is used to contain said lifting gas.

2. The wind turbine machine of claim 1 wherein the said lighter-than-air device is shaped

aerodynamically to develop lift thereby being a lifting body by virtue of its overall

shape.

3. The wind turbine machine of claim 1 wherein said exterior skin is designed in such a

way as to give a means for passive flight stability to said lighter-than-air device

including, but not limited to, passive stabilizer aerodynamic surfaces such as nonarticulating

horizontal, vertical, v-shaped or ring-wing stabilizers.

4. The wind turbine machine of claim 1 wherein said exterior skin is designed in such a

way as to give a means, including active articulating aerodynamic control surfaces of

any shape or size, for active flight stability to said lighter-than-air device.

5. The wind turbine machine of claim 1 wherein said exterior skin is designed in such a

way as to give a means, including aerodynamic wing surfaces of any size or shape, for

developing lift from said air flows striking said lighter-than-air device.

Patent Application of Douglas J. Amick for

“Tethered Wind Turbine” continued

Page 24

6. The wind turbine machine of claim 5 wherein the lift obtained from said means

is controlled and used to offset drag forces experienced by said means for

converting kinetic and inertial energy when said accelerated air flows travel

through the interior of said lighter-than-air device.

7. The wind turbine machine of claim 1 wherein said means for said lighter-than-air

device to be held against the force of the wind is connected with an adjustable harness

means to control pitch angle of attack of said lighter-than-air device, the purpose of

such adjustment being useful for maximizing energy output and improving flight

stability of said lighter-than-air device.

8. The wind turbine machine of claim 1 wherein the means for converting kinetic and

inertial energy of said accelerated air flows into useable energy is an impeller rotor

driven turbine coupled to an electrical generator that splits water into oxygen and

hydrogen gases, of which said oxygen and hydrogen gases are pumped down said

tether through tubing to storage containers at the base end of said tether.

9. The wind turbine machine of claim 1 wherein a primary tensile strength member of

said tether is constructed of carbon nanotube materials.

10. The wind turbine machine of claim 1 wherein said electrical conducting members of

said tether are constructed of carbon nanotube materials.

11. The wind turbine machine of claim 10 wherein said primary tensile strength

member of said tether are constructed of carbon nanotube materials.

12. The wind turbine machine of claim 1 wherein the lighter-than-air device is made using

Tedlar film material in said exterior skin.

Patent Application of Douglas J. Amick for

“Tethered Wind Turbine” continued

Page 25

13. The wind turbine machine of claim 1 wherein said exterior skin of said lighter-than-air

device uses aluminized polyester film material to contain said lifting gas.

14. The wind turbine machine of claim 1 wherein said lighter-than-air device is tethered to

a base shelter structure on the ground.

15. The wind turbine machine of claim 14 wherein a tether retractor mechanism exists to

pull-in and let-out said tether from time to time, as is needed.

16. The wind turbine machine of claim 15 wherein said retractor mechanism is

installed on a tower.

17. The wind turbine machine of claim 15 wherein said retractor mechanism is

installed on top of a building.

18. The wind turbine machine of claim 15 wherein said retractor mechanism is

installed on a vehicle.

19. The wind turbine machine of claim 15 wherein said retractor mechanism is

installed on a watercraft.

20. The wind turbine machine of claim 15 wherein said retractor mechanism is

installed on a sea buoy.

21. The wind turbine machine of claim 1 wherein there is a control module on said lighterthan-

air device that automatically pilots the craft in order to maintain stable flight and

proper altitude.

Patent Application of Douglas J. Amick for

“Tethered Wind Turbine” continued

Page 26

22. The wind turbine machine of claim 1 wherein said control module monitors and

adjusts load levels applied to said means for converting kinetic and inertial energy of

said accelerated air flows into useable energy.

23. The wind turbine machine of claim 1 wherein said control module monitors

meteorological data from a plurality of sensors and decides to retract the lighter-thanair

device into a base shelter structure during those times when certain logical criteria

are met, including but not limited to those times when there are severe storms or

extreme winds or lightning.

drag section profile, having an annulus with a funnel-like wind concentrator shape at the front

inlet, said inlet made to direct oncoming apparent wind into a turbine rotary engine within said

ring-wing, said turbine made to extract kinetic energy from said wind flowing through it, and an

outlet for air, which has moved through said turbine and is now in a lower energy state, to be

expelled from said ring-wing.

25. The ring-wing of claim 24 wherein said ring-wing is held from drifting downwind by

means of a tether that is affixed to a mass which is held stable by the force of gravity,

including a mass fixed to ground.

26. The ring-wing of claim 24 wherein said ring-wing has aerodynamic control surfaces

attached to it that imparts aerodynamic stability to said ring-wing.

27. The ring-wing of claim 24 wherein said ring-wing has aerodynamic lift surfaces

attached to it that impart aerodynamic lift to said ring-wing, allowing for said ringwing

to climb to higher altitudes and achieve higher energy output than would be

possible without said aerodynamic lift surfaces.

Patent Application of Douglas J. Amick for

“Tethered Wind Turbine” continued

Page 27

28. The ring-wing of claim 24 wherein said ring-wing has a pitch adjustor harness on

said tether attached to it that can be adjusted as needed to impart aerodynamic lift to

said ring-wing by varying the angle of attack of the entire ring-wing that said pitch

adjustor harness would affect, allowing for said ring-wing to climb to higher

altitudes and achieve higher energy output than would be possible without said pitch

adjustor harness.

purposes of acting as a wind amplifying shroud shaped to speed-up air flowing through an

internally mounted turbine, and, to simultaneously enclose a lighter-than-air lifting gas that

serves to lift said wind energy harvesting device to an altitude where wind currents are more

powerful.

of-drag section profile, having an annulus with a funnel-like fluid flow concentrator

shape at the front inlet, said inlet made to direct oncoming apparent fluid flow into a turbine

rotary engine within said ring-wing, said turbine made to extract kinetic energy from said fluid

flow flowing through it, and an outlet for said fluid flow, which has moved through said turbine

and is now in a lower energy state, to be expelled from said ring-wing.

31. The ring-wing of claim 30 wherein said ring-wing is held from drifting downstream by

means of a tether that is affixed to a mass which is held stable by the force of gravity,

including a mass fixed to the seafloor.

32. The ring-wing of claim 30 wherein said ring-wing has hydrodynamic control surfaces

attached to it that imparts hydrodynamic stability to said ring-wing.

33. The ring-wing of claim 30 wherein said ring-wing has hydrodynamic lift surfaces

Application of Douglas J. Amick for

“Tethered Wind Turbine” continued

Page 28

wing to climb to higher altitudes and achieve higher energy output than would be

possible without said hydrodynamic lift surfaces.

34. The ring-wing of claim 30 wherein said ring-wing has a pitch adjustor harness on said

tether attached to it that can be adjusted as needed to impart hydrodynamic lift to said

ring-wing by varying the angle of attack of the entire ring-wing that said pitch adjustor

harness would affect, allowing for said ring-wing to climb to higher altitudes and

achieve higher energy output than would be possible without said pitch adjustor

harness.

END OF PATENT APPLICATION