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DUAL-STAGE THRUST VECTOR DIRECTION CONTROL FOR MANEUVERABLE ROCKETS AND

VERTICAL-ORIENTED UNMANNED AIR VEHICLES

ABSTRACT

This dual-stage Thrust Vector Control (TVC) invention allows a rocket-shaped Upright Air Vehicle

to fly with stability and precise control. The instrumentation payload sits at top and the

thrusters are located at the bottom. The normally unstable condition with the center-of-mass

situated well above the thrusters is eliminated due to the dual-stage TVC mechanism with

onboard computer which corrects for the tendency to lean to a far inclination angle then tip and

topple over. The propulsion unit thrusters are ducted-fan jet engines or rocket motors which

have a small exit nozzle cross-sectional area in comparison to exposed helicopter or multi-rotor

unmanned air vehicle fan blades. This provides for a small ground footprint of the air vehicle

making suitable for small landing bases. The Upright Air Vehicle is remotely piloted and

command operated through a standard radio control transmitter or a radio frequency

communications station having a surveillance imaging camera.

BACKGROUND OF THE INVENTION

FIELD OF ENDEAVOR

The field of endeavor is Thrust Vector Control (TVC) or thrust direction control for guided

maneuverability and stabilized levitation of a vertical oriented Upright Air Vehicle or tall slender

rocket. This dual-stage TVC stabilization concept is novel in that no other system provides the

amount of precise navigation guidance control with accurate attitude stabilization necessary to

maneuver an Upright Air Vehicle without the tendency for loss of control by toppling-over and

eventual crashing.

BACKGROUND

The original idea for the attitude stabilization of a slow moving Upright Air Vehicle was to

resolve stability and robustness issues since the center-of-mass is well above the propulsion unit

thruster exit port and the cross-sectional area of the thrust stream is relatively small. The

Upright Air Vehicle can easily tip over being tall and slender and requires a more advanced

stabilization controller than commonly found in single-stage TVC in rocket and jet engine

designs. The robustness of the feedback controller must provide for precision maneuvering and

stability control operation in a natural environment involving disturbances such as wind, bumps

and accidental collisions with objects.

A rocket at point of lift-off has the tendency to tip and topple-over due to the top-heavy

condition of supporting a payload mass or weight up top and the propulsion unit thrusters

placed down at the bottom. Many early rockets lifted off the launching pad and almost

immediately flipped over striking the launching pad due to being top-heavy with near zero

vertical ascent velocity. At near zero ascent velocity no stabilizing aerodynamic forces can come

in effect. Accelerating to a particular ascent velocity the aerodynamic forces can assist in

stabilizing the attitude rate and level-flight orientation of the rocket body. In the case of rockets

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and missiles a lack of aerodynamic stabilizing forces can cause the projectile to cone, wobble

and even topple-over during flight. Any side force or disturbance bump at time of lift-off can

easily drive a rocket body into rotation and a loss of angular rate stabilization control can result

in an unrecoverable flip-over.

Laboratory demonstrations of stabilizing the inverted pendulum employ high feedback gain

controllers with inertial sensors and angular position sensors. I have built a hardware unit as a

proof-of-concept demonstrator of an Upright Air Vehicle in the inverted pendulum configuration

as shown in FIG. 9 which is considered metastable, marginally stable or stable over a small

bounded region.

Steering control authority delivers the amount of moment (force x arm) to rotate the airframe

body to a particular angular velocity or rate about either the center-of-mass for slow moving air

vehicles or center-of-pressure for fast moving air vehicles. Steering control authority for the

tripod stabilizer consists of the tilt angle excursion or deflection limit for a nacelle. Steering

control authority for a thrust director fin constitutes the rotation angle of the control shaft along

with the size or surface area of the fin. Steering control authority is defined by the amount of

angular momentum imparted to the air vehicle body and is an adjustable feature by setting the

angular extension limit of the TVC mechanisms and the surface area of the thrust director fins.

Different TVC methods as found in the prior art and current designs to change the angle of the

thrust direction vector relative to the air vehicle body are described as follows:

1) Rotatable thrust angle director fins that are located in the thrust/jet stream near or at the

nozzle exit port of the cylindrical shroud or tubular sleeve that surrounds the ducted fan or jet

engine. Thrust director fins or vanes are mounted to corresponding rotation shafts and are

placed directly within the flow stream where the angle of deflection of the vane or fin alters the

direction of the flow stream. Thrust director fins or vanes are suitable for ducted fans, where a

centered spider cross-flow brace supports the inner bearings for the fin shaft. The fins, fixed

spider brace, bearing support, thrust director fins and fin shaft in the thrust flow stream are

exposed to an exhaust flow at ambient temperature for ducted fans and extremely high

temperature for jet engines and rocket motor exhaust flow streams.

2) Paddles or pivotable walls, which are similar in shape to canoe oars, are placed along the

periphery of the exit nozzle stream and are tilted in order to move one or more paddles into the

exhaust flow stream. Arranging four paddles along the circumference or perimeter provides for

pitch-yaw axis steering control authority. Arranging six paddles provides for all three roll-pitch-

yaw axis steering control authority. Thrust deflector paddles are suitable for jet engines and

rocket motors where the temperature of the exhaust flow is much lower at the edges or

circumference of the stream than in the center. TVC paddles are typically found in jet engines

and rocket motors where the temperature at the periphery or edges of the exit flow stream can

be up to 2,000 °F and the center of the flow stream at 6,000 °F.

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3) A straight gimbaled cylindrical tube or sleeve is placed or positioned just past or slightly

downstream of the jet engine or rocket motor exhaust port exit nozzle which provides for pitch-

yaw or tip-tilt axis angular steering control authority. This design is commonly used in radio

control 3D model jet powered aircraft.

4) Gimbaled jet engines or rocket boosters with the gimbal axis of rotation located near the

nozzle waist or engine base for pitch-yaw or tip-tilt rotation steering control authority. Tilting

the propulsion unit nacelle for pitch-yaw attitude steering control authority is in a similar

manner to the straight gimbaled cylindrical tube TVC device described in (3) above.

5) Additional thruster nozzles to the main thruster which are throttled to change the boost

pressure distribution and the moment arm coupling distance with respect to the center-of-mass

of the rocket or Upright Air Vehicle. A similar approach is splitting off bypass jet streams from

the main thruster then using throttle flow valves in a differential manner to change the pressure

distribution across the exhaust exit port and affect the control forces and moments (force x

radius) for rotating the air vehicle body.

6) Lateral thrusters to direct the thrust in a radial direction thus translating and rotating the air

vehicle. Rotation of the air vehicle occurs by a coupling moment arm of the applied lateral force

relative to the center-of-mass. Lateral/radial or side pointing thrusters are typically used on

spacecraft and space vehicles to translate the vehicle body sideways, rotate the vehicle body to

a new orientation or pointing attitude, or perform a momentum dumping operation using

reaction wheels or control moment gyros. Momentum dumping using side pointing thrusters is

used to reduce the stored momentum to zero as an energy neutralizing effect in space based

attitude control.

Typical TVC designs of prior art place the pivot at or nearby the thruster engine/motor or

thruster nozzle which is positioned at the bottom of the rocket or Upright Air Vehicle. A small

change in thrust direction angle amounts to a large moment arm with respect to the center-of-

mass thus producing a large overturning moment which de-stabilizes the attitude control. A

large moment arm produces less accurate control and compromises precision. The geometry for

a tilting propulsion unit thruster as presented in the dual-stage TVC invention solves this large

moment arm problem by moving the hinge pivot point or gimbal axis much higher up the air

vehicle.

Helicopter and multi-rotor unmanned air vehicles are horizontal in orientation with large

diameter propulsion fan blades up at the top and the instrumentation payload down at the

bottom. Helicopters and multi-rotor copter unmanned air vehicles are configured in this

horizontal orientation which is opposite to that of a vertical oriented rocket or Upright Air

Vehicle with instrumentation payload placed up top and propulsion unit thrusters placed down

at the bottom of the airframe body.

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The helicopter or multi-rotor copter unmanned air vehicle operates in a stable condition due to

the propulsion blades being placed above the center-of-mass of the air vehicle. Guidance

navigation and attitude rate damping stabilization for a helicopter is by tip-tilting a swash plate

and for a multi-rotor unmanned air vehicle by varying the fan blade rotation speed. Varying or

modulating the fan blade speed for each of the rotors has a slow feedback control response

time in comparison to TVC methods. Propeller fan or rotor blade speed variation using motor

speed control for attitude stabilization of an Upright Air Vehicle is too slow and unsuitable for

controlling the metastable or marginally stable condition in order to maintain an upright level

flight orientation. Dual-stage TVC design provides quicker feedback control system

responsiveness and faster reaction times for stabilization than found when using motor speed

control for multiple ducted fan rotor propulsion units, throttled fuel to jet engine turbine

impellors or throttled fuel to rocket motors.

Typical heavy payload lifting rocket boosters and the liquid propellant booster on the space

shuttle use one or more single-stage TVC mechanisms/devices for their gimbaled or tip-tilting

rocket motors. In these cases the thruster axis-of-rotation pivot point is located near the

propulsion unit thrusters down near the bottom of the rocket body. Typically the dual-axis

gimbal pivot points are placed anywhere from the nozzle throat to the base of rocket motor.

The center-of-mass point for a rocket or Upright Air Vehicle body is near the middle section of

the body with the gimbaled TVC pivot point near the bottom of the body leaving a large vertical

height or elevation distance between the center-of-mass point and the TVC mechanism/device

pivot point or gimbal pivot center. The large vertical distance from the gimbaled TVC thrust

direction control pivot point to the center-of-mass point of the rocket produces a large

overturning moment arm for a small angular deflection of the TVC mechanism. This large

geometric coupling moment arm drives a powerful overturning moment (force x radius) which

leads to over-control, excessively high attitude tip-over rate and the overturning or flipping over

of the rocket or Upright Air Vehicle.

The dual-stage TVC mechanism solves this large overturning moment (force x radius) problem

by placing the TVC hinge rotation axis or pivot point high up on the airframe body above the

intake of the ducted fan propulsion unit thrusters and nearer to the vertical center-of-mass

point of a rocket or Upright Air Vehicle body. The advantage of the raised pivot point or hinge

axis nearer to the center-of-mass is greater angular deflection control accuracy, and precision

control and stabilization due to a geometrically reduced moment arm for any change in angle of

the thrust direction vector. This allows for optimization of the thrust direction angle and the

coupling moment arm distance with respect to the center-of-mass point on the air vehicle. This

feature can easily be applied to multiple propulsion unit thrusters on a rocket or missile with a

minor modification to the design of the airframe body.

As the thrusters get smaller in diameter for the same thrust force and the Upright Air Vehicle

height remains constant then the Upright Air Vehicle becomes more tippy and vulnerable to

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over-turning and subject to topple-over. This instability is due to the increased slenderness ratio

of the airframe height to center-of-mass distance relative to the diameter of the thruster or

body diameter of the airframe. Maintaining stability and control for taller more slender air

vehicle becomes more difficult and challenging so a more responsive feedback controller system

with less phase-lag delay and relatively high steering control authority becomes a more

stringent requirement.

The dual-stage TVC system and Upright Air Vehicle demonstrator as shown in FIG. 9 has been

flight tested and evaluated for the following: torque reaction since one of the three ducted fan

propulsion units is counter-rotating, steering control authority for small angular deflections of

the thrust director fins, angular excursion and response delay of the tilting/pivoting nacelle

servo actuator drive control system, tendency and vulnerability to tip and topple-over with all

nine attitude control tripod stabilizer and thrust director fin servo actuators set to neutral

positions, and thrust-to-weight ratio lifting capability given the capacity and weight of the

supported battery packs.

PRIOR ART AND CITED REFERENCES (U.S. PATENT DOCUMENTS)

A search through trade, scientific and engineering journals as well as the USPTO database and

Google patents database has revealed the following references to related prior art patents and

current design technology inventions.

References Cited

U.S. Patent Date Issued Inventor Class/Sub Title

5,662,290 9/2/1997 Voight 244/3.22 Mechanism for thrust vector control using multiple

nozzles

5,154,050 10/13/1992 Herup, et al. 60/230 Thrust vector control using internal airfoils

4,131,246 12/26/1978 Rotmans 244/3.22 Thrust vector control actuation system

5,110,047 5/5/1992 Toews 239/11 Vane-type nozzle(s) for varying the magnitude and

direction of a thrust vector, and methods of operating

same

All of these patents are for single-stage TVC and none for the dual-stage TVC concept.

The relevant USPTO classes and their respective subclasses are listed as follows:

1) 60/232 Power Plants - Reaction Motor (e.g., Motive Fluid Generator and Reaction Nozzle,

etc.) – Motive fluid outlet movable relative to motor part.

2) 239/265.19 Fluid Sprinkling, Spraying, and Diffusing – Reaction Motor Discharge Nozzle –

With means controlling amount, shape or direction of discharge stream.

3) 239/265.23 Fluid Sprinkling, Spraying, and Diffusing – Reaction Motor Discharge Nozzle –

Fluid jet for stream deflection.

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4) 239/265.27 Fluid Sprinkling, Spraying, and Diffusing – Reaction Motor Discharge Nozzle –

Selective total discharge through diversely shaped or directed outlets

5) 239/265.35 Fluid Sprinkling, Spraying, and Diffusing – Reaction Motor Discharge Nozzle –

Nozzle aiming adjustable.

6) 239/265.37 Fluid Sprinkling, Spraying, and Diffusing – Reaction Motor Discharge Nozzle –

Radially inwardly movable wall.

7) 239/265.39 Fluid Sprinkling, Spraying, and Diffusing – Reaction Motor Discharge Nozzle – At

least three pivoted flaps form outlet

8) 244/52 Aeronautics and Astronautics – Aircraft, Steering, Propulsion – Fluid-Aircraft steering

by regulating the movement of masses, jets or other fluid.

9) D12/16.1 Transportation – Special Purpose Vehicle – Drone, guided missile or rocket –

Transportation or conveyance vehicle.

10) D12/326 Transportation – Aircraft, Spacecraft or Fuselage – Vertical takeoff type.

11) D12/330 Transportation – Aircraft, Spacecraft or Fuselage – Ducted or shrouded fan.

12) D12/331 Transportation – Aircraft, Spacecraft or Fuselage – Canard configuration or with

plural distinct wings.

Search for current design technology in the trade journals, scientific publications and new

technology announcements have not revealed a similar concept to the dual-stage TVC invention

which employs two different types of TVC mechanisms/devices.

BRIEF SUMMARY OF THE INVENTION

Dual-stage Thrust Vector Control (TVC) solves the problem of flying a vertical-oriented “Upright

Air Vehicle” configured as an inherently unstable or marginally stable inverted pendulum

operating in real-world environments. The principle of TVC is to change the directional angle of

the exit nozzle flow stream or thrust direction vector with respect to the air vehicle longitudinal

axis or airframe body nominal thrust direction axis.

An Upright Air Vehicle is defined as a tall slender rocket-like shaped vertical-oriented air vehicle

or any other type of air vehicle where the center-of-mass of the air vehicle body is above the

exit port of the propulsion unit thruster nozzle. It is configured as a top-heavy air vehicle with

instrumentation payload up top and propulsion thrusters down bottom using TVC for guidance

control and attitude stabilization. An Upright Air Vehicle controllably hovers and maneuvers as a

tall and slender vertical-oriented air vehicle.

The Upright Air Vehicle is similar in attitude stability margin to a vertical-oriented tall and

slender rocket at point of lift-off where the pitch-yaw lean angle with respect to the

gravitational direction vector cannot exceed a limit. If the orientation from level flight exceeds a

limit then the Upright Air Vehicle will lose attitude control and orientation stability resulting in

topple-over. The similarity between the tall and slender rockets at point of lift-off and the

Upright Air Vehicle is that both have near zero vertical velocity and thus no aerodynamic forces

to act upon the center-of-pressure relative to the center-of-mass which affects the attitude

stabilization of the air vehicle body. The main difference between the rocket at point of lift-off

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and the Upright Air Vehicle is the Upright Air Vehicle hovers, flies and maneuvers in same

metastable or inherently unstable condition of marginal stability as that of the rocket. Another

difference of a rocket at point of lift-off to an Upright Air Vehicle with dual-stage TVC is that an

Upright Air Vehicle is intended to levitate, hover and maneuver at relatively low vertical velocity

in comparison to other air vehicle designs which strive for traveling at high velocity thereby

gaining greater stability. Hovering, flying and maneuvering at zero to a low vertical velocity

requires control robustness to disturbances through improved TVC capability which is achieved

by the dual-stage TVC mechanism/device of this invention.

Single-stage TVC in vertically launched rockets and missiles addresses the metastable or

marginally stable condition of maintaining low attitude rates or body rotation rates and level

orientation that occurs over a brief moment as the rocket or missile quickly accelerates past the

zero velocity condition to an aerodynamically stabilizing condition. Rockets are stabilized by the

aid of high velocity motion and the attitude stabilizing effect from aerodynamic forces. Vertical

launched rockets and missiles have longitudinal fins positioned along the bottom section and

extending to the base of a rocket for moving a center-of-pressure point behind the center-of-

mass point. The external longitudinal fins in the free stream increases stability by increasing

aerodynamic drag. This aerodynamic stabilization comes into effect when the rocket exceeds a

particular velocity.

The dual-stage TVC invention uses two different types of coupled single-stage TVCs to provide a

means to maneuver, guide and stabilize a vertical-oriented rocket or Upright Air Vehicle where

no aerodynamic stabilizing forces exist or have effect. The instability is primarily due to the

center-of-mass being located well above the thrusters relative to the exit port of the propulsion

unit thrusters which are placed down at the bottom of the airframe body. The secondary aspect

of instability is due to the small cross-sectional area or diameter of the thrusters relative to the

height from the thruster nozzle exit port to the center-of-mass of the airframe body which is

represented by the tall and slender aspect of a rocket or an Upright Air Vehicle.

Vertical oriented rockets, missiles and Upright Air Vehicles are all equally subject to tipping over

to any side or direction being represented by a tip-tilt pivot or pitch-yaw rotation with the

vector sum of the two-axis producing a lean angle. The lean angle initiates a direction of flight

along a path.

The dual-stage TVC invention comprises a tandem-coupled dual-stage TVC mechanism/device

with Inertial Measuring Unit (IMU) sensor suite used for attitude rate feedback to an onboard

real-time processing microcontroller or other type of numerical processing computer to achieve

the required guidance control and attitude stabilization for an Upright Air Vehicle being in a

metastable or marginally stable flight condition. Control robustness is achieved by an accurate

and precise IMU sensor suite and high-bandwidth dual-stage TVC feedback controller for

imbalance correction.

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The onboard computer includes algorithms for pilot operator input command signal processing,

autopilot stabilizer, avionics flight controls, multi-state feedback controller, inertial sensor signal

processing, multiple sensor fusion of gyros to accelerometers to magnetometers, and vectored

Pulse-Width Modulated (PWM) output signals to drive the dual-stage TVC servo actuators. The

onboard flight control computer with floating point unit microprocessor or Field Programmable

Gate Array (FPGA) running at over 100 MHz with all autopilot and other software algorithms

provides for high-speed feedback control response in order to maintain attitude stability and

hold a steady orientation being exposed to real-world environments with disturbance forces,

moments (force x radius) and random shocks to the air vehicle body. Robust stabilization and

control is maintained in the presence of pilot operator errors, elements of nature and random

unexpected disturbance forces such as wind buffeting, bumps, and accidental collisions with

objects.

The dual-stage TVC device/mechanism couples two different types of single-stage TVCs which

provides for large amplitude steering control along with high- frequency response bandwidth

control and low delay time reactions. This dual-stage TVC concept/invention provides greater

control accuracy and orientation/attitude precision by locating the tip-tilt or pitch-yaw axis pivot

point high-up and well above the thruster exit port plane and relatively close to the longitudinal

or vertical center-of-mass of the air vehicle body. Thus greater attitude control and stabilization

is achievable for a smaller footprint-to-height slenderness ratio as well as smaller footprint-to-

thrust ratio for lift and payload weight carrying capacity given a tall-and-slender rocket or

Upright Air Vehicle.

The first-stage TVC of the dual-stage TVC mechanism/device tilts or pivots the high mass

moment-of-inertia propulsion unit thrusters or nacelles for large amplitude excursion response

and low-frequency response bandwidth steering control authority of the air vehicle body or

airframe. The second-stage TVC of the dual-stage TVC mechanism/device rotates thrust director

fins placed in the thrust stream at the nozzle port exit for high-frequency bandwidth response

and low angular excursion displacement steering control authority of the air vehicle body. The

combination of the two single-stage TVC mechanisms/devices forms the dual-stage TVC

mechanism/device which provides the added feature of high-frequency response bandwidth

along with high amplitude angular displacement excursion limit for enhanced steering control

authority of the Upright Air Vehicle.

The dual-stage TVC design also provides for the smallest footprint-to-thrust ratio which means

that its slender and narrow size gives an Upright Air Vehicle access into confined spaces and

tight passageways while carrying a heavy instrumentation payload such as surveillance cameras,

sensors and instrumentation. Since the cameras, lasers and instrumentation equipment are

placed at the top of the Upright Air Vehicle then the pilot operator can use first person viewing

video goggles or monitor to peer over and past large fallen objects or obstacles in collapsed

disaster sites, confined tunnels, narrow corridors, cluttered conduits, tight passageways, and

mining shafts where the ceiling clearance distance above an obstructing object is minimal.

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Conditions and damages can still be assessed due to the capability to peer above and beyond

the large blocking obstacle even though the ceiling clearance is small. This capability is not

available with multi-rotor copter unmanned air vehicles since the cameras are suspended from

the bottom of the airframe.

The novel feature of the dual-stage TVC device is that a high-speed response and low angular

displacement TVC mechanism is coupled in tandem to a low-speed response and high angular

displacement TVC mechanism in order to substantially improve orientation stability and

significantly increase attitude rate damping control of a slow maneuvering Upright Air Vehicle

body.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The figures illustrate the configuration and application of the principles behind the operation of

the dual-stage TVC invention.

FIG. 1 shows an isometric view of the entire configuration consisting of three nacelle propulsion

thrusters configured in a tripod stabilizing geometry.

FIG. 2 shows a top view of the tripod stabilizer bulkhead plate and the exact geometric

layout/configuration.

FIG. 3 shows a side view detail of a single nacelle with servo-actuator to change the angle of

thruster with respect to a single axis pivot or hinge.

FIG. 5 shows a single thruster configuration which exploits the same principle of operation by

straddling the power batteries or fuel cells across the central thruster propulsion unit.

FIG. 6 shows the top view of the single thruster configuration where four batteries or fuel cells

are arranged to straddle the thruster in a balanced configuration using four support arms for the

battery power units or fuel supply cells.

FIG. 7 shows a block diagram of the command signal inputs and control outputs to the servo

actuators of the dual-stage TVC device along with the inertial sensor interface for feedback

stabilization.

FIG. 8 shows a feedback control loop architecture diagram for attitude based guidance and

feedback control correction for errors in Upright Air Vehicle orientation and attitude rate with

respect to commands and the level orientation which is referenced to the gravity direction

vector.

FIG. 9 shows a front view photograph of a developmental prototype unit for proof-of-principle

demonstration which is used to provide a means to assess the effectiveness and performance of

the dual-stage TVC invention as applied to an Upright Air Vehicle.

DETAILED DESCRIPTION OF THE INVENTION

The fundamental concept of the dual-stage Thrust Vector Control (TVC) mechanism/device and

feedback control system is to provide steerable propulsion lift to a top-heavy Upright Air Vehicle

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or tall slender rocket that can easily tip-over using a common single-stage TVC

mechanism/device. The dual-stage TVC device consists of one or many vertical-oriented

propulsion unit thrusters with two different independent tandem coupled TVC devices for

guidance control and attitude/orientation stabilization. The dual-stage TVC mechanism/device

and control system addresses a levitational slow moving vertical-oriented Upright Air Vehicle

that is designed to operate in natural environments subject to wind forces, collision with

objects, bumping into obstacles and general loss of control such as veering off from the

intended flight path.

A single-stage TVC system is typically used in vertical launched rockets and missiles including

Vertical Take-Off and Landing (VTOL) aircraft and some jet aircraft to provide for attitude

stabilization where no aerodynamic forces are in effect. High ascent velocity provides stabilizing

aerodynamic forces that act upon the center-of-pressure of the airframe body. At low velocity

the aerodynamic forces are negligible and the thrust forces and any other external body forces

will act about the center-of-mass of the airframe body thus creating a moment (force x radius).

Forces with a moment arm about the center-of-mass or forces that do not pass through the

center-of-mass will set the airframe body into rotation such as the pitch-yaw axis for attitude

rate about the level flight condition.

One of the main differences between the dual-stage TVC invention for Upright Air Vehicles and

rockets is that an Upright Air Vehicle flies continually at low vertical velocity where no stabilizing

aerodynamic forces come into effect. The dual-stage TVC mechanism provides the necessary

degrees-of-freedom for control along with a fast response and quick reaction time feedback

loop in order to stabilize an Upright Air Vehicle without relying on any aerodynamic forces to

achieve the required stabilization.

The metastable or inherently unstable condition occurs when the center-of-mass is well above

the exit port of the propulsion unit thrusters being a top-heavy condition, which is similar in

principle to the classical inverted pendulum stabilization problem, balancing on a unicycle, or

maintaining an upright pencil upon the palm of the hand. The top-heavy condition is aggravated

by placing the cameras, lasers, sensors and instrumentation up top while maintaining a slender

narrow cross-sectional body profile. The tendency to tip-over is increased for a higher center-of-

mass relative to a small propulsion pressure distribution footprint.

The top-heavy metastable or inherently unstable balancing condition of the Upright Air Vehicle

is representative of the inverted pendulum which uses a sled, inertial sensor, and position

sensor in a real-time feedback loop controller to dynamically balance a tall and slender rod on

end. The typical configuration for the inverted pendulum is a ball-bearing placed at the bottom

of the rod which connects to a moving sled. The sled moves back and forth in order to balance

the rod or inverted pendulum on-end and hold or maintain this upright position. The metastble

condition is aggravated by the low friction ball-bearing which easily allows for the flip-over of

the pendulum. Thus the balance point for maintaining the upright condition is over a small

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region of error. The inverted pendulum stabilizer has been demonstrated in laboratory

experiments and the concept applied heavy payload lifting rockets using single-stage gimbaled

TVC boosters or other methods for controllably directing the thrust stream relative to the

airframe body. The application of TVC on tall slender vertical-oriented rockets or Upright Air

Vehicles at near zero vertical ascent velocity is especially important since they are vulnerable to

a sufficiently high de-stabilizing angular rates leading to large tip-lean attitude angles or pitch-

yaw orientation angles with respect to the gravitational direction vector.

One of the main differences between the inverted pendulum based TVC mechanism and the

dual-stage TVC invention is that the inverted pendulum demonstrator uses a personal computer

tower case or laptop computer for real-time numerical processing and running of the control

algorithms. The dual-stage TVC design uses an onboard microcontroller or Field Programmable

Gate Array (FPGA) integrated circuit for real-time Hardware In-Loop (HWIL) control functions

which can be found on a small 3x2 inch size circuit board. This allows for mounting of all

command, communications, avionics and autopilot control functions in software, firmware and

electronics hardware to be directly installed onto the Upright Air Vehicle airframe for

convenient Radio Frequency (RF) remote control.

The comparison of flying the Upright Air Vehicle to an upside down helicopter as an inverted

pendulum is that both are inherently unstable and require inertial gyroscope sensors connected

to a real-time feedback control loop. The helicopter uses a swash plate and the Upright Air

Vehicle uses a dual-stage TVC mechanism/device to maintain the inverted flying condition. The

stabilizing difference between an inverted flying helicopter and an Upright Air Vehicle is that the

a helicopter has a large area of swath from the large diameter rotor blades in comparison to an

Upright Air Vehicle which uses a high-speed ducted fan, jet engine, fan boost jet engine or

rocket motor thruster with much smaller cross-sectional area propulsion swath for lift force

generation. The Upright Air Vehicle propulsion unit thrusters have a significantly smaller

diameter rotor and cross-sectional area in comparison to the helicopter blade diameter and

cross-sectional area swath. The smaller thrust cross-sectional area swath and the vertical

distance from thruster exit port to center-of-mass of the Upright Air Vehicle makes for a more

unstable condition as compared to the inverted helicopter.

It becomes more difficult to maintain the metastable or marginally stable condition as the

rocket or Upright Air Vehicle external diameter or single thruster diameter decreases and/or the

height increases. The property of marginal stability in a metastable condition can be explained

by maintaining a ball on top of a hill or peak which is stable as long as the hill does not rock or

shift. Any disturbance to the ball or shifting of the hill will cause an unstable condition of the ball

and the result will be that the ball rolls down either side of the hill. The steeper the incline or

slope of the hill then the more challenging it is to maintain the metastable or marginally stable

condition which occurs when the center-of-mass rises in elevation and/or the diameter of the

propulsion unit thrusters or air vehicle body decreases.

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The external diameter of the rocket or Upright Air Vehicle and instability relationship is based on

the ratio of the center-of-mass height with respect to the thruster exit port and the cross-

sectional area or footprint size of the propulsion unit thruster. The taller and more slender the

rocket or Upright Air Vehicle, the more vulnerable it is to instability and the more difficult to

control and maintain orientation stability within the metastable condition.

The first-stage pivoting nacelle TVC device provides for low bandwidth frequency control due to

the relatively high mass moment-of-inertia of the nacelle in comparison to a thrust director fin

in the nozzle exit flow stream.

This first-stage of the dual-stage TVC director mechanism/device is arranged as a tripod

stabilizer with three equally spaced hinge rotation axis or a pivot point that is placed above the

intake of the thrusters as shown in FIGS. 1 and 3. This geometric configuration of the hinge

rotation axis or pivot point placement provides an optimum swing arm geometry and angular

travel extension or excursion limit for the nacelle and propulsion unit thrusters resulting in very

accurate and precise angular deflection of the nacelles for thrust direction control. The optimum

geometry of the swing arm produces a moment arm that avoids severe over-control which can

lead to high airframe overturning rate and flip-over. This undesirable geometric condition is

found in common gimbaled rocket motor TVC.

The first-stage of the dual-stage TVC device changes the thrust direction angle of the nacelle

which consists of a propulsion unit and shroud, sleeve, tube or extended nozzle. The cylindrical

shroud, tubular sleeve or extended nozzles encases the propulsion unit, provides attachment to

the thruster propulsion unit, and the tubular sleeve or nozzle extends downstream of the

propulsion unit to allow for placement of the thrust director fins that are positioned inside and

through the thrust flow stream. The base of the cylindrical sleeve now becomes the exit nozzle

instead of the exit port of the propulsion unit thruster.

The tripod stabilizer provides for first-stage TVC in the pitch-yaw axis only and consists of three

single-axis hinge pivots attached to swing arms that tilt each of three nacelles constituting the

propulsion unit thrusters and their respective nozzles. The swing arms and nacelles are single-

axis hinge pivoted at the corners of an equilateral shaped triangular platform forming a

bulkhead which is attached to a central column. The tilting or pivoting of each of the three

nacelles or propulsion unit thrusters thereby changes the direction of the thrust. Independently

tilting the three nacelles or nozzles provides for pitch-yaw or lean-bank attitude/orientation

control. The nacelles are arranged in an equal distance separated triangular pattern similar to

that of a three-legged tripod supporting a camera. Three individual nacelles are single-axis hinge

pivoted and arranged in the pattern or shape of an equilateral triangle to form a tripod

stabilizing TVC stage that operates by tilting the nacelles. The advantage of tilting the nacelle

thrusters in the tripod stabilizer configuration is the three nacelles can respond to large

magnitude external forces and unexpected high energy impacts to the airframe.

Dual TVC

13

A nozzle is a cylindrical tube or sleeve ring that surrounds a ducted fan or jet engine thruster

propulsion unit with mounting brackets for attachment or coupling and the cylindrical sleeve

which extends past the exit nozzle of the thruster and supports the aerodynamic steering fins

placed into the thruster exit flow stream. The steering fins are rotated on a hinged pivot to

change the direction of the thrust vector as a nacelle directing TVC device or stage. A nacelle

comprises or consists of a propulsion unit with cylindrical sleeve and attached steering fins

which are hinged plate surfaces or airfoils in the exit thrust flow stream.

The tripod stabilizer presents the minimum number of propulsion unit nacelles required for tip-

tilt or pitch-yaw or lean-bank axis rotation control which are placed along the bulkhead corners

to provide for guidance control and attitude error correction. The tripod stabilizer can be

expanded to accommodate any number of additional (greater than three) propulsion unit

thrusters. The propulsion unit thrusters can be ducted fans, turbines, jet engines, rocket motors

or other types of propulsion unit devices.

Servo actuators driving the pivoting steering fins in the thruster flow stream and tilting nacelles

coupled to inertial gyros and accelerometers and an onboard microcontroller computer

provides for closed-loop real-time autopilot feedback control and attitude stabilization. The pilot

operator provides command guidance to the air vehicle along a flight path for surveillance and

other mission operations.

The tripod stabilizer concept is not particularly limited to this particular equilateral shaped

triangular geometric configuration and the principle of operation is consistent with as few as

one to any number of nacelles or propulsion unit thrusters. The tripod stabilizer configuration is

the preferred mode but can be substituted with a single propulsion unit thruster connected to a

two-axis pivot universal joint or ball joint to laterally shift the center-of-mass with respect to the

thrust vector as shown in FIG. 5 dual-stage TVC for a single thruster.

The tandem coupling arrangement or configuration of steering fin directors in the thrust stream

and tripod arrangement of tilting nacelles comprises the preferred mode dual-stage TVC

mechanism/device for an Upright Air Vehicle or other application.

The principle of dual-stage TVC is not limited to the number of thruster propulsion unit nacelles

and is equally effective for any number of thruster unit nacelles. Multiple thrusters greater than

three as in the tripod stabilizer can be equally separated by radial angle and arranged as 1) Four

thrusters connected to a square shaped bulkhead, 2) Five thrusters connected to a pentagon

shaped bulkhead, 3) Six thrusters connected to a hexagon shaped bulkhead, 4) Seven thrusters

connected to an heptagon shaped bulkhead, and so on.

The second-stage thrust director fin or vane TVC device of the dual-stage TVC system provides

pivoting of fins by a rotation shaft which are supported by the nozzle near the exit outlet.

Turning the rotation shaft changes the angle of the fin or vane in the thrust stream for thrust

Dual TVC

14

direction steering control. The resultant reaction force and moment (force x radius) causes the

air vehicle to set about a rotation rate and change orientation.

As few as two thrust director fins per nozzle will provide for all three roll-pitch-yaw axis control

when using the tripod stabilizer configuration. More than two fins per nozzle can be distributed

around the circumference of the nozzle for all three roll-pitch-yaw axis control when using only

a single propulsion unit thruster in a nacelle.

The fastest response feedback control configuration with minimal delay or lag to the Upright Air

Vehicle is available through the thrust director fins since they have a lower mass moment-of-

inertia in comparison to the pivoting or tilting of the heavy propulsion unit thrusters or nacelles.

The advantage of the tilting nacelle TVC stage is increased excursion limit control for response to

large amplitude disturbances with high steering control authority for lower bandwidth

frequency excitations.

The preferred mode of operation is with two fins per nozzle as shown in FIGS. 1, 3 and 7. The

single nacelle TVC configuration in FIGS. 5 and 6 shows four thrust director fins in the flow

stream nozzle which provides greater degrees-of-freedom attitude control than two thrust

director fins in the nozzle.

A single fin with control shaft and thrust director blade is shown in FIGS. 3 and 4 where the TVC

steering control authority depends on the rotation angle excursion limit and the surface area of

the fin plate or blade. The number of thrust director fins supported by a nozzle can

accommodate up to the maximum number that can be fitted to the circumference of the

cylinder sleeve or tube ring nozzle.

The pilot operator inputs flight commands through gimbaled sticks on either a Radio Control

(RC) transmitter or RF command and control station. Flight control sticks command

thrust/throttle level and roll-pitch-yaw attitude with the possibility of more channels for

additional control functions. Camera image video data from the Upright Air Vehicle can be RF

telemetry downlink transmitted to the ground control station view screen monitor, video screen

or First Person Viewing (FPV) goggles. The images can then be processed and analyzed with

either an onboard FPGA or ground control image processor.

A command from the pilot operator such as holding a steady stick angle will maintain a steady

attitude of the airframe body. The inertial attitude rate sensing or angular rate sensing gyro

signals are numerically integrated and then compared to the command attitude for air vehicle

orientation correction in a feedback control loop. Stick commands are different for aircraft

where holding a steady stick angle command represents a constant angular velocity or attitude

rate of the airplane. A fixed stick angle commanding a steady or constant attitude rate feedback

control approach would lead to the toppling over of an Upright Air Vehicle so feedback control

for steady attitude is the preferred method. Since steady attitude or orientation hold control is

Dual TVC

15

the preferred configuration then pilot operator command and guidance of the dual-stage TVC

Upright Air Vehicle is based on a tip or lean angle to the air vehicle airframe body.

In order for the stick angle to command a steady attitude or orientation of the airframe, the

gyro attitude rate sensors require integration along with coordinate frame rotation algorithms

using either Euler rotation sequence coordinate frame transformation matrices or quaternion

based vector operations with coordinate frame transformation matrices.

The avionics controller provides guidance navigation and control with all vector math operations

from operator commands to the dual-stage TVC mechanism/device actuators. The autopilot

controller provides attitude stabilization and maintenance against the tipping over condition by

integrating or combining inertial measuring unit sensor signals as a multiple sensor fusion

algorithm. The real-time feedback controller interfaces with the dual-stage TVC devices and

inertial measuring unit sensors to control the flight path and orientation of the airframe.

Instead of three nacelle propulsion unit thrusters as found in the tripod stabilizer, the principle

of a dual-stage TVC can be applied to a single propulsion unit thruster providing that the single

swing arm is connected to a two-axis swivel pivot such as a universal joint or ball joint. The

single thruster dual-stage TVC configuration is shown in FIGS. 5 and 6 where the nozzle is

supporting four thrust director fins for more degrees-of-freedom control since the number of

nacelle thrusters has been reduced from three to one. The main difference with the single

thruster dual-stage TVC design is that the power batteries or fuel cells have been moved from

the central column or post to straddle the nacelle or propulsion unit thruster nozzle assembly.

Angular swinging the universal joint swivel pivot shifts the center-of-mass with respect to the

thrust direction vector which provides the desired TVC steering control authority. The shift or

offset produces a moment arm where the thrust direction vector no longer passes through the

center-of-mass and TVC is achieved by controlling the two-axis pivot angle using two servo

actuators. Two-axis hinge pivot articulation that uses two servo actuators to change the tip-tilt

angle of the nacelle is achieved in a similar manner as shown in FIG. 3 which depicts a single-axis

servo drive mechanism for tilting a nacelle. The preferred mode of operation uses triple thruster

propulsion units arranged in the tripod stabilizer configuration as illustrated in FIGS. 1 and 9 but

the advantage of using a single propulsion unit thruster with dual-stage TVC thrust direction

control is also feasible.

The dual-stage TVC or thrust director controller device with a single or any number of

tilting/pivotable nacelle propulsion unit thrusters is designed to lift, propel and maneuver a tall

slender rocket or vertical oriented Upright Air Vehicle at low vertical velocity to no vertical

velocity. It can hover above the ground with greater stability than existing designs.

The dual-stage TVC device comprises a tilting nacelle TVC stage for steering control authority, a

thrust director steering fin TVC stage for additional steering control authority, IMU sensors, pilot

operator command inputs interface and an onboard real-time flight microcontroller computer.

Dual TVC

16

The tilting nacelle TVC stage controls the inclination angle of the propulsion unit thruster using a

servo actuator and a swing arm hinge pivot that is attached to the propulsion unit. The thrust

director steering fins within the thrust flow stream is a plate or blade that intercepts the flow

stream by the rotation or turning of a shaft. As the angle of the fin changes then the surface

area of the fin changes the direction of the thrust vector. A servo actuator controls the shaft

rotation angle. The servo actuators are command driven by PWM signals which moves the

rotation control arm to a particular angular position. PWM signals are encoded in the

microcontroller computer and sent out to each of the individual servos.

The microcontroller functions and input/output interfaces are shown in the block diagram of

FIG. 7. The microcontroller receives input commands from the pilot operator, fuses the signals

from the multiple inertial sensors such as gyros, accelerometer and magnetometer, performs

avionics and flight path guidance control functions, performs autopilot stabilization functions,

gyro signal processing and integration from rate to angular position, digital signal filtering,

quaternion vector operations, coordinate frame transformations from fixed inertial frame to

relative body frame, vector math operations to correctly command all the servo actuators in a

closed-loop feedback controller, and PWM signal encoding and decoding transformations. The

microcontroller receives PWM input command signals from the pilot operator, receives analog,

Serial Peripheral Interface (SPI) and Inter-Integrated Circuit (I2C) signals from the IMU sensors,

and sends out encoded PWM command signals to all the servo actuators. The primary interfaces

to the microcontroller are: pilot operator command inputs, IMU multiple sensor inputs and

dual-stage TVC device outputs.

The layout of the dual-stage TVC mechanism/device is shown in FIG. 1 and the arrangement of

the components. The dual-stage TVC operates as a combined pivot based TVC for the nacelle

with additional TVC thrust director fins in the nozzle of each thruster. The dual-stage TVC

concept of operation is described as 1) A swing arm about a single-axis pivot point or hinge line

which connects/attaches to the nacelle and changes the direction or angle of the thrust and 2)

Two thrust director fins per nozzle placed in the thrust flow stream just past the exit nozzle of

the propulsion unit.

The preferred mode of the dual-stage TVC invention using three propulsion unit thrusters is

illustrated in FIG. 1 as an equilateral triangular shaped pattern with single-axis hinge pivots at

the corners to direct the thrust angle. The propulsion unit thruster is shrouded with a cylindrical

tube or nozzle which extends past the exit port of the thruster to support the thrust director fins

that are placed in the thruster flow stream. Two thrust director fins per nozzle provides for all

three roll-pitch-yaw axis rotation control.

FIG. 1 shows that the turbine (being ducted fan, jet engine or rocket motor) (1) is placed in a

tubular nozzle housing (2) which surrounds and supports the turbine unit. The nozzle supports

thrust director fins (3) which are placed located/positioned at the exit port of the nozzle in order

to direct the thrust into the free stream of the surrounding air space. The angle of the director

Dual TVC

17

fins is determined by rotating shaft (4) using a servo actuator device. A nacelle comprises items

(1-4). The turbine unit (1) and nozzle device with thrust director steering fins in the thrust flow

stream (2-4) are attached to a swing arm bracket (5). The swing arm bracket is connected to

single axis-of-rotation hinge pivot (6) which orients the pointing direction of the entire nacelle or

turbine/nozzle combination unit (1-4). The single-axis hinge pivots (6) are mounted to the

corners of an equilateral triangular shaped bulkhead plate (7) which supports three nacelles (1-

4) with swing arm brackets (5). The identical nacelles (1-4) are configured in a triangular

geometry with a 120 degree angle between each nacelle to form a tripod stabilizer. The tripod

stabilizer support bulkhead plate (7) attaches to the central triangular column tube (8). Many

other bulkheads attach to the triangular stanchion post or tubular column (8) which supports

control servos, batteries or fuel, turbine speed controllers, instrumentation such as cameras and

lasers, avionics controllers, autopilot navigation and stabilization controllers, and inertial

measuring unit sensors such as gyros, accelerometers, magnetometers.

The equilateral shaped triangular bulkhead as shown in FIG. 2 shows attachment to the central

post or column with the three hinge pivots at each corner which are for attachment to the three

swing arms for moving the nacelles or propulsion unit thrusters in an arc.

FIG. 2 shows a top view of an equilateral triangle with 120 degree angular separation providing

equidistance separation for the three swing arm brackets (5). The equilateral triangular shaped

bulkhead plate (7) forms the geometry for the tripod stabilizer. A cut-out triangle in the center

allows the column or stanchion post (8) to slip and pass through for fastening at the appropriate

height along the column (8). Three pivot point hinges (6) are attached to the outside corners of

the tripod stabilizer bulkhead plate (7). The tripod stabilizer bulkhead plate (7) accommodates

three nacelles or turbine based propulsion unit thrusters however the principle remains valid for

any number of additional turbine thrusters connected to the bulkhead plate (7).

The swing arm control method for pivoting a nacelle TVC mechanism/device is shown in FIG. 3.

An RC servo actuator is mounted to a small bulkhead platform which has a rotating arm that

drives a pushrod linkage. The pushrod linkage translates back and forth which connects to the

nacelle at the other side of the servo actuator. The nacelle is attached to a swing arm which is

hinge pivoted at the top of the bracket above the intake of the propulsion unit thruster. The

other side of the single-axis hinge(s) is attached to the equilateral shaped triangular bulkhead

platform. This forms the control mechanism/device that swings and tilts each of the three

pivoting nacelle TVC mechanisms/devices and controls the thrust direction vector. The tripod

stabilizer pivot point or hinge rotation axis of the swing arm is placed above the intake of the

thrusters nearer to the center-of-mass of the Upright Air Vehicle which provides for more

precise angular deflection control of the nacelles. The TVC or thrust direction steering control

authority depends on the tilt angle excursion limit of the swing arm that articulates the thrust

direction vector.

Dual TVC

18

FIG. 3 shows mechanical servo actuator (9) control for tilting a nacelle (1-4) about the hinge

rotation axis or pivot point (6) located at the corners of the equilateral triangular bulkhead (7)

and the ends of the swing arms (5). A ducted fan outline (1) with rotor and motor unit is shown

inside the nozzle (2). The high speed air flow of the thrust flow stream is directed across the

thrust director fins (3) and a detail of a thrust director fin (3) depicting the rotation shaft and

blade is shown at the bottom-right of FIG. 3. Rotation of the thrust director fin shaft (4) by servo

actuators (12) (not shown in FIG. 3) controls the direction of the exit flow stream. A servo

actuator (9) which is attached to a bulkhead plate (11) rotates an arm which connects to a ball

link and tie rod combination (10) to produce linear motion that translates the nacelle (1-4) with

respect to the air vehicle body (8) over a translational displacement along the x-direction. This

linear motion causes the swing arm (5) to rotate over angle θ with respect to the hinge-axis

pivot point (6).

FIG. 4 shows the mechanical servo actuator (12) control for a thrust director fin (3). The servo

actuator (12) is attached to the nozzle (2) that shrouds the propulsion unit thruster (1) and

supports the thrust director fin unit (3-4). The servo actuator arm (13) rotates to drive a

connecting linkage rod (14) in translation to another rotation arm (15) which is attached to the

thrust director fin shaft (4). Articulation of the servo actuator (12) causes the thrust director fin

shaft (4) to rotate and swing the thrust director fin (3) within the thrust stream of the nozzle (2).

FIGS. 5 and 6 show the dual-stage TVC mechanism/device configured for a single turbine or

propulsion unit thruster (1-4) using a dual-axis pivot universal joint or ball joint (18) attached to

the end of a swing arm (17). The central thruster (1) and nozzle (16) is straddled or flanked with

batteries or fuel cells (20) arranged in a balanced manner such that servo actuators attached to

the shroud, cowling or tubular sleeve nozzle (16) can drive the straddled or flanked power

sources (20) and move them side-to-side. The dual-axis pivot or universal joint (18) attaches to

the end of the swing arm (17) and the saddle bracket (19) which supports the battery or fuel cell

power sources (20).

The angular articulation of the propulsion unit thruster (1) and nozzle (16) with respect to the

straddled or flanked power sources (20) about the pivot point (18) produces a shift in thrust

direction vector with respect to the center-of-mass of a single thruster. This provides a means

for TVC of a single thruster Upright Air Vehicle.

The dual-axis tip-tilt articulation of the nacelle is similar in design to the nacelle single-axis tilt

TVC device as shown in FIG. 3 except that a dual-axis tip-tilt nacelle TVC operates with two servo

actuators instead of single servo actuator for single-axis tilt only control. The nozzle (16)

supports four thrust director fins instead of two for more degrees-of-freedom in thrust direction

control.

The block diagram of FIG. 7 shows the guidance commands entering the real-time feedback

controller along with the avionics flight controller and the autopilot with inertial sensors that are

attached to the airframe for feedback correction. The input command signals enter a real-time

Dual TVC

19

microcontroller for mathematical vector processing and send out Pulse-Width Modulation

(PWM) signals to the dual-stage TVC servo actuators as well as the motor or engine speed

controller. An onboard numerical processing microcontroller computer on a 3x2 inch sized

circuit board provides all of the avionics flight control and autopilot functions. The onboard

microcontroller computer also receives pilot operator commands, receives inertial measuring

unit sensor signals, and processes vector/matrix operations on all signals which are then sent

out to the PWM servo actuators of the dual-stage TVC devices.

FIG. 7 defines the control flow from pilot operator commands to the onboard numerical

processing microcontroller computer and its interface with avionics, autopilot, adaptive gain

feedback controller, cameras, lasers, inertial measuring unit sensors, sensor fusion and the dual-

stage TVC devices with multiple servo actuators. The microcontroller computer can also control

a two-axis azimuth and elevation angle gimbal which supports the camera and laser set up. The

inputs to the numerical processing microcontroller are multiple channel pilot operator

commands and inertial sensors such as multiple three-axis gyros, three-axis accelerometer,

three-axis magnetometer, altimeter and possibly a Global Positioning System (GPS) transponder.

The outputs from the numerical processing microcontroller are to the PWM servo actuators

found in the dual TVC devices and the two-axis azimuth and elevation gimbal torque motors.

The feedback control diagram of FIG. 8 illustrates a command controller that provides guidance

and stabilization due to the inertial sensors placed on the airframe. The inertial measuring unit

sensor suite consists of gyros, accelerometers, heading magnetometers and altimeters that are

output signal fused to provide for low error level flight and maintain the upright attitude

condition with respect to the gravitational direction vector. The gyro sensors are attitude rate

integrated to provide orientation feedback control with respect to the stick position of

commanded signal. The pilot operator input commands enter a real-time microcontroller

computer which operates mathematical algorithms and processes the inertial measuring unit

sensor signals and then combines or fuses the variables into signals that drive the servo

actuators which are connected to the dual-stage TVC mechanisms as well as the throttle speed

controllers.

The feedback control diagram also provides for numerical integration of the gyro inertial sensor

angular rate outputs or the numerical integration of the quaternion rate vector components

whose vector is based on the gyro outputs to produce an estimated attitude/orientation vector

of the airframe body. This estimated attitude/orientation vector is used as a feedback signal for

comparison to the command signals from the pilot operator. The comparison of the input to

sensor feedback signals are converted to the error signal which is used in the adaptive gain

feedback controller design for the dual-stage TVC mechanism/device. This configuration that

uses attitude/orientation of the airframe for feedback is the preferred control law for the dual-

stage TVC since in this configuration the command and control minimally affects the tendency to

drift away from the most stable or the metastable safe operating zone/region for a level flight

operating condition.

Dual TVC

20

FIG. 8 shows a feedback control diagram for a steady command stick angle that produces a

steady attitude or orientation of the airframe. The gyro inertial sensor signals represent attitude

rate and are integrated to represent the sensed attitude of the airframe. The attitude command

signals are compared to the sensor signals to produce an error signal which is amplified by an

adaptive gain controller. The amplified signals are then sent to the dual-stage TVC servo

actuator mechanisms in a closed-loop feedback network to affect rotations on the Upright Air

Vehicle body.

FIG. 9 shows a constructed prototype demonstration unit for the dual-stage TVC control concept

as applied to an Upright Air Vehicle. Additional components to those already described are a

microcontroller (21) with numerical processing floating point unit on a circuit board with

numerous input/output interface pins for receiving operator pilot command signal from an RC

receiver (21), receiving inertial measuring unit (22) sensor signals, receiving camera (23) image

video signals, sending out control signals to the two-axis azimuth and elevation gimbal

controller, and sending out control signals to the various servo actuators. The inertial measuring

unit (22) consists of multiple three-axis gyros, accelerometers and magnetometers, and top

mounted camera (23) attaches to a two-axis azimuth and elevation gimbal for directing the line-

of-sight direction vector of the camera and tracking a desired target within the image.

The prototype demonstrator model as seen in FIG. 9 is used to test and evaluate the principle of

dual TVC and the constructed Upright Air Vehicle measures to 15 inches in diameter at the base

and 20 inches tall and produces 10 lbs of thrust from the three thrusters. Electric ducted fans

are inserted into tubular nozzles and each nozzle supports two thrust director fins. Mounted on

the top bulkhead is a camera (23) and on the third bulkhead there is a microcontroller board for

avionics guidance, autopilot control and stabilization. Including an array of MEMS inertial

guidance gyros, accelerometers and magnetometer sensors constituting the inertial measuring

unit which are mounted to an aluminum cube (22). The hinge rotation pivots (6) for the tripod

stabilizer can be seen for two of the three nacelles (1-4). Beneath the equilateral triangular

bulkhead plate (7) are the electronic speed control units (24) for the ducted fan motors (1) and

the power source batteries (25) for the ducted fans (1) are seen to be attached to the central

triangular column (8). Some of the thrust director fins (3) can be seen to extend past the edge of

the nozzle port (2).

The meta-stable condition of maintaining the upright flying condition is uniquely accomplished

by a dual-stage TVC mechanism/device that is dynamically controlled by an onboard computer

for fast, accurate and precise attitude stabilization. The dual-stage TVC device and real-time

computer controller offers a high temporal speed at a low angular displacement TVC stage that

is tandem coupled to a low temporal speed at high angular displacement actuation stage for

greater stability and control than found in current designs and the prior art.

Dual TVC

21

The combination of the dual-stage TVC devices, inertial sensors and onboard microcontroller

computer corrects for extreme lean, tip or inclination angles and damps out high rotation rates

in all roll-pitch-yaw axes.

The propulsion unit thrusters, consisting of ducted fans, jet engines, fan boost jet engines or

rocket motors, have a small exit nozzle cross-sectional area in comparison to helicopter and

multi-rotor unmanned air vehicle fan blades. The small diameter propulsion unit thrusters

provides for a small ground footprint of the air vehicle which allows for take-off and landing

upon small bases. Operating a RC helicopter in the inverted flight condition is more stable than

the Upright Air Vehicle because the helicopter blade swath is large with respect to the height

from the rotor blades to the center-of-mass.

The Upright Air Vehicle is remotely human piloted and command operated through a standard

RC transmitter or a RF communications station and equipped with surveillance imaging

streamed video receiver. Hobbyist RC control for airborne drones, air vehicles, helicopter and

multi-rotor unmanned air vehicles are typically equipped with FPV cameras which use a

different RF frequency from the transmitter for downlink streaming of real-time video data to

the pilot operator. FPV guidance through an air vehicle camera provides for navigation even

when the pilot operator has lost sight or direct visual contact with the air vehicle and typically

wears vision goggles or views a monitor for observing the flight path direction of the unmanned

air vehicle, multi-rotor copter or drone.

A feature of the dual-stage TVC Upright Air Vehicle is that it has a smaller footprint size or cross-

sectional area in comparison to a propeller based propulsion unit air vehicles typical found in

helicopter and multi-rotor unmanned air vehicles. This provides the heaviest of payload lifting or

suspended object carrying capacity with accessibility into narrow corridors, small conduits, tight

hallways, cluttered passageways and obstructed confined spaces due to the smallest footprint-

to-thrust ratio. The small footprint and precision control available to the pilot operator of the

Upright Air Vehicle allows it be landed on narrow ledges, small structural frames, fly into trees

with dense foliage and branches, and fly close to aerial telephone wiring for close-up inspection.

For example, when using jet engine thrusters an Upright Air Vehicle could lift logs from a dense

forest or carry commercial air conditioners and roofing materials to the top of buildings and

position heavy equipment onto their mounts.

The main advantage of this dual-stage TVC mechanism/device invention is that it allows for

heavy payloads such as cameras, lasers, sensors and instrumentation to be mounted up top

which aggravates the metastable situation or condition of holding marginal stability by raising

the elevation position of the center-of-mass. The lowest footprint-to-thrust ratio is also due to a

relatively high thrust-to-diameter ratio as found in ducted fans, jet engines and fan boost jet

engines whose rotors spin at much higher speed than on helicopter rotors and the multi-rotor

copter blades of unmanned air vehicles. The lowest footprint-to-thrust ratio is also found in

rocket booster motors with solid or liquid combustible propellant.

Dual TVC

22

One of the advantages of using propulsion devices such as ducted fans and jet engines with

shrouded impellors over helicopters and multi-rotor unmanned air vehicles with exposed

propeller blades is that the ducted fans and jet engines are completely shrouded so less debris

and foreign matter can get sucked down the intake or through the exposed rotor blades of a

helicopter or multi-rotor unmanned air vehicle.

While this invention has been described in detail it is not limited to the exact embodiment

shown because this claim merely serves as an illustrative embodiment. This illustrative

embodiment of the invention shows the design and construction of the invention as an example

for the proof-of-concept and principle-of-operation as shown in FIG. 9.

DESCRIPTION OF THE NUMBERED COMPONENT ITEMS FOUND IN THE DRAWING

A numbered list of parts and components as depicted in the figures along with quantity and

material where applicable is presented as follows:

1) Turbine or Jet Engine or Electric Ducted Fan (Qty 3)

2) Tubular Shroud Covering the Turbine Extending to an Exit Nozzle Supporting the Thrust

Director Fins (Qty 3) (molded plastic or fiber reinforced plastic)

3) Thrust Director Fins (Qty 2 per Nozzle) (carbon graphite strip or plate)

4) Rotation Shaft for Director Fins (Qty: 1 per Director Fin) (carbon graphite rod)

5) Swing Arm Bracket for Nacelle (Qty 3) (sheet aluminum or carbon graphite plate)

6) Single-Axis Hinge Pivot or Flexure Bearing (Qty 3) (brass or steel for hinges and metal or

plastic for flexure bearings)

7) Triangular Support Bracket for Swing Arms or Tripod Stabilizer Bulkhead (Qty 1) (sheet

aluminum or carbon graphite plate)

8) Triangular Shaped Cross-Section Post/Column (Qty 1) (clam shell laminated aluminum strips

or thin walled extruded aluminum or shaped carbon graphite strips)

9) Servo Actuator for Nacelle attached to Swing Arm (Qty 3)

10) Ball Link & Tie Rod or Pushrod from Servo to Nacelle (Qty 3)

11) Nacelle Servo Support Bulkhead (Qty 1) (sheet aluminum or carbon graphite plate)

12) Servo Actuator for Thrust Director Fin (Qty 2 per Nozzle)

13) Servo Actuator Arm (Qty 1 per Servo)

14) Ball Link & Tie Arm or Pushrod from Servo to Thrust Director Fin (Qty 1 per Servo)

15) Control Arm to Director Fin Shaft (Qty 1 per Nozzle)

16) Tubular Shroud or Thrust Nozzle Supporting Four Thrust Director Fins (Qty 1) (molded plastic

or fiber reinforced plastic)

17) Swing Arm Bracket for Nacelle (Qty 1) (sheet aluminum or carbon graphite plate)

18) Dual-Axis Pivot Universal Joint or Ball Joint (Qty 1)

19) Saddle Bag Style Wrapped Battery or Fuel Cell Support Bracket (Qty 1) (sheet aluminum)

20) Power Batteries or Fuel Cells (Qty 4)

21) Avionics and Autopilot Computer (Microcontroller or FPGA) and RC Receiver (Qty 1)

22) Inertial Measuring Unit (IMU) Sensors (Three-axis Gyros, Accelerometers, Magnetometers)

(Qty 1)

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23) Camera, Laser, Sensor Instrumentation and Two-axis Tracking and Pointing Gimbal Stage

(Qty 1)

24) Electronic Speed Controller (ESC) for Electric Ducted Fan (EDF) (Qty 3)

25) EDF Battery (Qty 3)

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CLAIMS OF THE INVENTION

1. I claim that enhanced stabilization and greater maneuvering capability is hereby improved by

using a dual-stage Thrust Vector Control (TVC) system with onboard computer control to

dynamically articulate thrust direction for a tall slender rocket-like shaped vertical oriented air

vehicle or any other type of air vehicle where the center-of-mass of the air vehicle body is above

the propulsion unit thruster exit nozzle port, herein referred to as an “upright air vehicle”,

whereby it levitates, hovers and moves laterally in a stable orientation as a normal flying

condition due to a dual-stage tandem coupled TVC system comprising two different types of TVC

mechanisms/devices.

2. The said dual-stage TVC system of Claim 1 further includes a means to provide the amount of

deflection angle that is imparted to the nominal thrust stream direction which initiates and

drives the air vehicle body rotation rate as an upright air vehicle reacted angular rate body

motion and is herein defined as the “steering control authority” whereby a high steering control

authority, based on a large moment (force x radius) applied to the upright air vehicle airframe

body, thereby increases controllability and enhances robustness for operation in natural

environments with disturbances.

3. The said dual-stage TVC system of Claim 1 provides a means for the preferred mode

configuration instead of single-stage TVC or a single TVC mechanism/device as found in current

design and the prior art wherein a multiple stage TVC system or a plurality of stages for a TVC

system, such as a triple-stage TVC system, also provides for similar functionality to affect TVC

steering direction articulation, steering control authority and attitude stabilization.

4. The said dual-stage TVC system of Claim 1 provides for a novel design means in that current

designs and the prior art for TVC as applied to vertical launch rockets and missiles and for

Vertical Take-Off and Landing (VTOL) aircraft as well as radio control model 3D jet planes as

implemented using a jet engine, fan boost jet engine or rocket motor propulsion unit thruster

are described as:

a) A tilting propulsion unit thruster or nacelle using a torque motor driven gimbal actuator to

affect steering control authority;

b) A straight cylindrical tube placed downstream or aft of a fixed propulsion unit thruster to the

airframe that is tip-tilt angle rotation controlled (or articulated) by a gimbal actuator to affect

steering control authority;

c) A set thrust director steering fins that are inserted into the exit nozzle thrust stream and

redirect the thrust stream flow such that rotational forces and moments (force x radius) are

applied to the airframe in order to affect steering control authority;

d) A set of thrust deflector steering paddles, which are similar in shape to a canoe oar, that are

positioned along the periphery of the exit thrust stream, which may contain hot expansion gases

especially found in the core central region of the thrust stream, and are tilted to move and enter

into the exit thrust stream in order to redirect the effluent flow and apply rotational forces and

moments (force x radius) to the airframe in order to affect steering control authority;

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e) A throttle control for additional thruster nozzles to the main propulsion unit thruster in order

to affect steering control authority;

f) A set of lateral thrusters aligned along a radial direction to exert side forces and coupling

moments (force x radius) about the center-of-mass to affect steering control authority.

5. The said two different types of TVC mechanisms/devices cited in Claim 1 wherein are

composed of:

a) A first-stage TVC mechanism/device (1-2,5-7) that consists of a tilting propulsion unit thruster

(1) TVC stage mechanism/device or a tilting nacelle (1-4) TVC stage mechanism/device consisting

of three tilting hinge (6) pivoted nacelles (1-4) connected to the three corners of a equilateral

shaped triangular bulkhead platform (7), herein defined as a tripod stabilizer (1-2,5-11) for the

preferred mode configuration of operation and furthermore other bulkhead geometry

configurations such as a square with four corners, pentagon, hexagon, heptagon, octagon, etc of

said bulkhead platform shape can be optionally selected using a multiple set of hinge pivoted

nacelles (with one single-axis hinge pivoted nacelle connected at each corner of the geometric

shaped bulkhead platform) for said upright air vehicle to supply thrust direction steering control

authority and attitude stabilization;

b) A second-stage TVC mechanism/device (3-4,12-15) that comprises a thrust director fin TVC

stage mechanism/device containing a plurality of thrust director fins (3) per nozzle or a thrust

deflector paddle TVC stage mechanism/device containing a plurality of thrust director paddles

per nozzle for said upright air vehicle of Claim 1 to supply thrust direction steering control

authority and attitude stabilization.

6. The said first-stage TVC mechanism/device of Claim 5 wherein provides the properties of high

angular deflection excursion or displacement limit at a low-speed reaction time constants or low

frequency response and the said second-stage TVC mechanism/device of Claim 5 wherein

provides the properties of high-speed reaction time constants or high frequency response at a

low angular deflection excursion or displacement limit whereby the dual-stage tandem coupled

TVC system of Claim 1 provides a means for exploiting the combined advantages from both TVC

stages thereby enhancing controllability with increased steering control authority of an upright

air vehicle being operated in a marginally stable or metastable condition which is vulnerable to

tipping and toppling-over from relatively small disturbance forces.

7. The said combined advantages from both stages TVC stages of Claim 6 provides a means for

large angular displacement excursion limit along with fast action response TVC actuators as

compared to the slow reaction response of multiple thruster throttle regulation TVC or rotor

speed control TVC actuation as found in the prior art.

8. The said first-stage TVC mechanism/device of Claim 5 wherein provides a means for an

equilateral triangular shaped bulkhead platform (7) that connects to hinge pivot points (6) which

are (substantially) elevated above the intake of the propulsion unit thrusters (1) provides for

optimization of the overturning moment arm whereby angular deflection tilting of a propulsion

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unit thruster (1) and the respective moment that acts about the longitudinal or vertical center-

of-mass point of the air vehicle body thereby establishing the optimal geometry for the moment

arm distance with respect to an angular deflection and improving steering control authority.

9. The said dual-stage TVC system of Claim 1 provides a means to use thrust stream flow

director fins or deflector paddles wherein to controllably change the thrust stream flow

direction which is reacted by a rotational force or moment (force x radius) to an upright air

vehicle that initiates angular acceleration and angular momentum in the following rotational

directions:

a) Pitch-axis inclination angle to pitch or rock forwards or backwards;

b) Roll-axis tilt or lean angle to roll or bank over sideways;

c) Yaw-axis heading angle to turn left or right;

wherein the longitudinal axis of the airframe is aligned to the yaw-axis which is also parallel to

the nominal thrust direction vector and rotations about the pitch-axis and roll-axis which sets

the direction of flight due to inclination and leaning angles of the upright air vehicle airframe.

10. The inclination and leaning angles of the upright air vehicle airframe of Claim 9 provides a

means such that when set to zero then the upright air vehicle does not move in a lateral

direction and the nominal thrust direction vector which passes through the center-of-mass of

the upright air vehicle as the gravitational direction vector is parallel aligned to the longitudinal

axis or yaw-axis of the upright air vehicle body whereby the highest attitude stabilization factor

for level orientation and flight direction initiation is maintained.

11. The said dual-stage TVC system of Claim 1 wherein provides a means for the increased

steering control authority of Claim 6 that includes quick response to commands, external

disturbances, and correction to errors with respect to guidance control commands and inertial

sensor measurements; whereby a human pilot operator directs navigation and flight path

guidance commands from a remote station through an airwave Radio Frequency (RF)

communication link to an onboard RF receiver module mounted to the airframe.

12. The said onboard RF receiver module of Claim 11 provides a means to decode the RF signal

into discrete channels whereby the modulated signals of each channel are sent to the said

onboard computer (21) of Claim 1 for signal processing and vector-matrix mathematical

algorithm operations before the modified signals are sent out to the throttle or thrust

controllers of the multiple propulsion unit thrusters (1) and the various servo actuators (9,12) of

the dual-stage TVC system for roll-pitch-yaw angle vector guidance control and attitude

stabilization.

13. The said human pilot operator of Claim 11 provides a means to view the direction of flight of

the upright air vehicle from a remote location based on a video camera mounted up top of the

upright air vehicle which allows for air vehicle guidance through First Person Viewing (FPV) as

the upright air vehicle can be out of sight from the location of the said transmission base

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console as the camera video surveillance signals are then airwave RF transmitted back to the

pilot operator’s viewing goggles or monitor.

14. The said onboard computer (21) of Claims 1 and 12 provides a means to receive the

modulated signals of the various onboard RF receiver channels, the formatted signal data or raw

analog signals from the Inertial Measuring Unit (IMU) sensor package (22) which comprises

three-axis gyros, three-axis accelerometers and three-axis magnetometers and the said onboard

computer (21) sends out modified output signals to the throttle or thrust electronic speed

controllers (24) of the multiple propulsion unit thrusters (1) and the various servo actuators

(9,12) of the dual-stage TVC system whereby batteries (25) supply power through the Electronic

Speed Controller (ESC) regulators (24) to the propulsion unit Electric Ducted Fan (EDF) (1)

thrusters.

15. The said onboard computer of Claims 1 and 12 provides a means comprising either a real-

time floating point unit numerical microprocessor or Field Programmable Gate Array (FPGA) that

consists of software algorithms, mathematical libraries, custom feedback control programs and

firmware control that receives signals from the onboard RF receiver, Inertial Measuring Unit

(IMU) sensors (22) and outputs signals to the throttle/thrust level controllers (24) as well as the

TVC actuator servos (9,12) and provides the following signal processing functions:

a) Flight planning control for auto-navigation;

b) Calibration of IMU sensors and level-flight adjustment by balancing the thrust from multiple

propulsion unit thrusters;

c) Conversion of PWM signals from the RF receiver channels to numerical floating point values;

d) Conversion of inertial sensor analog output signals or SPI/I2C formatted output signals to

numerical floating point values;

e) Numerical vector and matrix math operations on input signals followed by conversion to

PWM signals in order to drive the each of the TVC mechanisms/devices;

f) Conversion of measured attitude rate or angular velocity from gyro sensors and conversion to

attitude or orientation using quaternion vectors and matrices or by using gyro rate integrators

and Euler transformation matrices;

g) Auto-pilot stabilizer and adaptive gain real-time feedback controller for tracking pilot

operator commands;

h) Sensor fusion for different types of IMU sensors to reduce significant gyro drift error and

cancel common mode bias/drift error based on signal mixing integration and specific

combinations of individual sensors;

i) In-flight periodic gyro sensor drift correction updates based on accelerometer sensor signal

inputs to a quaternion vector initialization function;

j) Digital signal processing functions such as low-pass filtering, high-pass filtering, band-pass

filtering, digital sampling anti-alias (error) filtering.

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16. The said various servo actuators of Claim 14 provides a means for all servo actuators (9,12)

to receive angular position signals for their rotatable servo output arms (13) from the said

onboard computer (21) wherein a servo actuator (9,12) comprises:

a) An electrical cable to transmit encoded control signals to the device for setting an angular

position of the rotatable output arm and power to drive the electrical servo motor;

b) Mounting flanges for attachment to structure;

c) Accurate and precise angular position resolution of the rotatable servo output arm (13);

d) High torque and high speed response to rotate and quickly slew to an updated command

position.

17. The said tilting nacelle (1-4) TVC stage mechanism/device of Claim 5 consists of a propulsion

unit ducted fan, jet engine or rocket motor that is inserted into and attached to the nozzle

where the nozzle supports a complete thrust director fin servo actuator control mechanism and

comprises the following:

a) A nacelle (1-4) with associated servo actuator (9) and hinge-pivot mechanism to rotate or

swing the propulsion unit thruster (1) in order to change the direction vector of the thrust;

b) A pivotable swing arm bracket (5) that is attached to the nozzle (2) which is used to rotate

and swing the propulsion unit thruster (1) about a single-axis hinge (6) pivot point;

c) A single-axis pivot point hinge (6) that is attached at the top of the swing arm bracket (5);

d) An upper bulkhead platform (7) that attaches the single-axis pivot point hinge (6);

e) A lower bulkhead platform (11) that attaches the tilting nacelle servo actuator (9);

f) A servo actuator (9) rotation arm that connects to a mechanical turnbuckle tie-rod or pushrod

linkage (10);

g) The same mechanical turnbuckle tie-rod or pushrod linkage (10) that connects to a bracket

mounted to the external surface or exterior surface cylindrical wall of the nozzle (2).

18. The said tilting nacelle (1-4) TVC stage mechanism/device of Claim 17 further includes the

following advantages:

a) The hinge pivot point (6) is placed high up above the intake of the propulsion unit thruster (1)

relative to the translation turnbuckle tie-rod bar or pushrod linkage (14) located near the

bottom of the nozzle (2) is the large elevation distance increases stabilization by reducing the

overturning moment (force x radius) which is due to a reduced moment arm length for an

angular deflection rotation of the nacelle as outlined by the path of the swing arm bracket;

b) Improved airframe positional accuracy, precision and control due to the TVC system is

achieved when the pivot point (6) for the tilting nacelle (1-4) is placed near the center-of-mass

of the upright air vehicle airframe body such that the moment arm distance with respect to the

center-of-mass provides for optimum steering control authority with no excessive overturning

moment (force x radius) magnitude due to a large moment arm or a lack of moment magnitude

which occurs due to a small moment arm.

19. The said tripod stabilizer of Claim 5 wherein comprises three tilting nacelle (1-4) propulsion

unit thrusters (1) arranged in a radial direction on an equilateral triangle shaped bulkhead

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platform (7) with a 120 degree separation angle between the nacelles and single-axis hinge pivot

points (6) located at the corners which provides for tip-tilt or pitch-roll axis attitude or

orientation control with respect to the level-flight condition where the level-flight condition is

defined by a parallel alignment of the longitudinal orientation of the airframe body axis or the

yaw-axis to the gravitational direction vector.

20. The said thrust director fin TVC stage mechanism/device of Claim 5 comprises:

a) A cylindrical encasing tube or surrounding sleeve enclosing the propulsion unit and that

extends past the exit port of the propulsion unit is herein defined as the nozzle (2) which

supports rotatable thrust director fins (3) that are placed downstream of the propulsion unit

thruster exit port which includes attachment brackets or braces for mounting a propulsion unit

thruster (1) to the nozzle (2) as well as supporting complimentary servo actuators (12) to drive

the rotational motion of each thrust director fin(s) (3);

b) The thrust director fins (3) can be shaped as an airfoil surface with rotation pivot axis shaft (4)

at the thickest section of the airfoil or shaped as a fin with a flat panel surface whose edge is

attached to a shaft (4) for rotation as the thrust director fin (3) is inserted into the nozzle (2)

such that rotation of the shaft (4) changes the direction of the thrust stream.

c) A plurality of thrust director fin servo actuators (12) with attachment hardware which are

mounted to the external surface of the cylindrical tube nozzle (2);

d) An attachment brace or mounting bracket affixed to the side of the nozzle (2) connects to a

mechanical turnbuckle tie-rod or pushrod linkage (14) that attaches to the crankarm (15) in

order to rotate the thrust director fin shaft (4);

e) A servo actuator rotation arm (13) that connects to a mechanical turnbuckle tie-rod or

pushrod linkage (14);

f) An attachment interface bracket to the nozzle (2) for connecting the mechanical turnbuckle

tie-rod or pushrod linkage (14);

g) The same mechanical turnbuckle tie-rod or pushrod linkage (14) that connects to the

crankarm (15) which is secured to the thrust director shaft (4).

h) Central inner bearing hub and spider brace to support the thrust director fin(s) shaft (4);

i) Outer bearing(s) placed along the circumference of the nozzle to support the thrust director

fin(s) shaft;

21. Alternatively a dual-stage TVC mechanism/device for a single propulsion unit thruster or

single propulsion unit nacelle (16) is realizable providing the single-axis hinge pivot for the swing

arm bracket (17) is replaced with a two-axis universal joint or ball joint pivot (18), and there are

more than three thrust director fins per nozzle (16), and that the battery power supply or fuel

cell units (20) are mounted to a modified laterally symmetrical bracket or frame (19) which

straddles the central propulsion unit thruster plus nozzle or nacelle (16) and that the nozzle

connects to the swing arm bracket (17) which attaches to universal joint or ball joint pivot (18)

wherein the battery power supply or fuel cell units (20) are weight balanced in a radial direction

about the centered pivot point (18) location.

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FIG. 1 - Nacelles Arranged in an Equilateral Triangular Pattern Comprising a Tripod Stabilizer

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FIG. 2 - Equilateral Triangular Bulkhead with Single-Axis Hinge Pivots at Corners

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FIG. 3 - Servo Actuator Drive Mechanism for Tilting Nacelle TVC Stage and Thrust Director Fin

Detail

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FIG. 4 - Servo Actuator Drive Mechanism for a Thrust Director Fin TVC Stage

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FIG. 5 - Dual-Stage TVC Mechanism/Device for a Single Propulsion Unit Thruster using a Dual-

Axis Universal Joint or Flexure Joint or Ball Joint

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FIG. 6 - Dual-Stage TVC Mechanism/Device for a Single Propulsion Unit Thruster Showing the

Straddling Support Bracket for Power Batteries or Fuel Cells

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FIG. 7 - Dual-Stage TVC Guidance Navigation and Control Block Diagram

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FIG. 8 - Dual-Stage TVC Simplified Feedback Control Flow Diagram

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FIG. 9 - Constructed Proof-of-Concept Flight Demonstration Prototype Upright Air Vehicle with

Dual-Stage TVC Mechanisms/Devices, Onboard Flight Computer, Inertial Measuring Unit

Sensors and Surveillance Video Camera Mounted Up Top