Introduction to UAV Systems
Description
The latest edition of the leading resource on unmanned aerial vehicle systems
In the newly revised Fifth Edition of Introduction to UAV Systems, an expert team of aviators, engineers, and researchers delivers the fundamentals of UAV systems for both professionals and students in UAV courses. Suitable for students in Aerospace Engineering programs, as well as Flight and Aeronautics programs, this new edition now includes end-of-chapter questions and online instructor ancillaries that make it an ideal textbook.
As the perfect complement to the author's Design of Unmanned Aerial Systems, this book includes the history, classes, and missions of UAVs. It covers fundamental topics, like aerodynamics, stability and control, propulsion, loads and structures, mission planning, payloads, and communication systems. Brand-new materials in areas including autopilots, quadcopters, payloads, and ground control stations highlight the latest industry technologies.
The authors also discuss:
* A thorough introduction to the history of unmanned aerial vehicles, including their use in various conflicts, an overview of critical UAV systems, and the Predator/Reaper
* A comprehensive exploration of the classes and missions of UAVs, including several examples of UAV systems, like Mini UAVs, UCAVs, and quadcopters
* Practical discussions of air vehicles, including coverage of topics like aerodynamics, flight performance, stability, and control
* In-depth examinations of propulsion, loads, structures, mission planning, control systems, and autonomy
Perfect for professional aeronautical and aerospace engineers, as well as students and instructors in courses like Unmanned Aircraft Systems Design and Introduction to Unmanned Aerial Systems, Introduction to UAV Systems is an indispensable resource for anyone seeking coverage of the latest industry advances and technologies in UAV and UAS technology.
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Persons
The late Paul Fahlstrom was a Naval Aviator (Marine Pilot) who held positions at NASA's Goddard Space Flight Center and the Department of Transportation.
The late Thomas Gleason, PhD, was Founder of Gleason Research Associates, an engineering and scientific analysis firm conducting evaluations related to missile and sensor systems.
Mohammad H. Sadraey is Associate Professor of Aeronautical Engineering at Southern New Hampshire University. He has authored five books, including Aircraft Design: A Systems Engineering Approach and Aircraft Performance Analysis.
Content
Preface
Aerospace Series List
Acknowledgments
List of Acronyms
Part One
Introduction
1. History and Overview
1.1. Overview
1.2. History
1.2.1. Early History
1.2.2. The Vietnam War
1.2.3. Resurgence
1.2.4. Joint Operations
1.2.5. Desert Storm
1.2.6. Bosnia
1.2.7. Afghanistan and Iraq
1.2.8. Long-Range Long-Endurance Operations
1.3. Overview of UAV Systems
1.3.1. Air Vehicle
1.3.2. Mission Planning and Control Station
1.3.3. Launch and Recovery Equipment
1.3.4. Payloads
1.3.5. Data Links
1.3.6. Ground Support Equipment
1.4. The Aquila
1.4.1. Aquila Mission and Requirements
1.4.2. Air Vehicle
1.4.3. Ground Control Station
1.4.4. Launch and Recovery
1.4.5. Payload
1.4.6. Other Equipment
1.4.7. Summary
1.5. Global Hawk
1.5.1. Mission Requirements and Development
1.5.2. Air Vehicle
1.5.3. Payloads
1.5.4. Communications System
1.5.5. Development Setbacks
1.5. Predator Family
1.5.1. Predator Development
1.5.2. Reaper
1.5.3. Features
1.6. Top UAV Manufacturers
1.7. Ethical Concerns of UAVs
Questions
2 Classes and Missions of UAVs
2.1. Overview
2.2. Classes of UAV Systems
2.2.1. Classification Criteria
2.2.2. Classification by Range and Endurance
2.2.3. Classification by Missions
2.2.4. The Tier System
2.3. Examples of UAVs by Size Group
2.3.1. Micro UAVs
2.3.2. Mini UAVs
2.3.3. Very Small UAVs
2.3.4. Small UAVs
2.3.5. Medium UAVs
2.3.6. Large UAVs
2.4. Expendable UAVs
Questions
Part Two
The Air Vehicle
3 Aerodynamics
3.1. Overview
3.2. Aerodynamic Forces
3.3. Mach Number
3.4. Airfoil
3.5. Pressure Distribution
3.6. Drag Polar
3.7. The Real Wing and Airplane
3.8. Induced Drag
3.9. Boundary Layer
3.10. Friction Drag
3.11. Total Air-Vehicle Drag
3.12. Flapping Wings
3.13. Aerodynamic Efficiency
Questions
4 Performance
4.1. Overview
4.2. Cruising Flight
4.3. Range
4.3.1. Range for a Non-Electric-Engine Propeller-Driven Aircraft
4.3.2. Range for a Jet-Propelled Aircraft
4.4. Endurance
4.4.1. Endurance for a Non-Electric-Engine Propeller-Driven Aircraft
4.4.2. Endurance for a Jet-Propelled Aircraft
4.5. Climbing Flight
4.6. Gliding Flight
4.7. Launch
4.8. Recovery
Questions
5 Flight Stability and Control
5.1. Overview
5.2. Trim
5.2.1. Longitudinal Trim
5.2.2. Directional Trim
5.2.3. Lateral Trim
5.2.4. Summary
5.3. Stability
5.3.1. Longitudinal Static Stability
5.3.2. Directional Static Stability
5.3.3. Lateral Static Stability
5.3.4. Dynamic Stability
5.4. Control
5.4.1. Aerodynamic Control
5.4.2. Pitch Control
5.4.3. Directional Control
5.4.4. Lateral Control
Questions
6 Propulsion
6.1. Overview
6.2. Propulsion Systems Classification
6.3. Thrust Generation
6.4. Powered Lift
6.5. Sources of Power
6.5.1. Four-Cycle Engine
6.5.2. Two-Cycle Engine
6.5.3. Rotary Engine
6.5.4. Gas Turbine Engines
6.5.5. Electric Motors
6.6. Sources of Electric Energy
6.6.1. Batteries
6.6.2. Solar Cells
6.6.3. Fuel Cells
6.7. Power and Thrust
6.7.1. Relation between Power and Thrust
6.7.2. Propeller
6.7.3. Variations of Power and Thrust with Altitude
Questions
7 Air Vehicle Structures
7.1. Overview
7.2. Structural Members
7.2.1. Skin
7.2.3. Fuselage Structural Members
7.2.3. Wing and Tail Structural Members
7.2.4. Other Structural Members
7.3. Basic Flight Loads
7.4. Dynamic Loads
7.5. Structural Materials
7.5.1. Overview
7.5.2. Aluminum
7.6. Composite Materials
7.6.1. Sandwich Construction
7.6.2. Skin or Reinforcing Materials
7.6.3 Resin Materials
7.6.4. Core Materials
7.7. Construction Techniques
7.8. Basic Structural Calculations
7.8.1. Normal and Shear Stress
7.8.2. Deflection
7.8.3. Bulking load
7.8.4. Factor of Safety
7.8.5. Structural Fatigue
Questions
Part Three
Mission Planning and Control
8 Mission Planning and Control Station
8.1. Introduction
8.2. MPCS Subsystems
8.3. MPCS Physical Configuration
8.4. MPCS Interfaces
8.5. MPCS Architecture
8.5.1. Fundamentals
8.5.2. Local Area Networks
8.5.3. Levels of Communication
8.5.4. Bridges and Gateways
8.6. Elements of a LAN
8.6.1. Layout and Logical Structure (Topology)
8.6.2. Communications Medium
8.6.3. Network Transmission and Access
8.7. OSI Standard
8.7.1. Physical Layer
8.7.2. Data-Link Layer
8.7.3. Network Layer
8.7.4. Transport Layer
8.7.5. Session Layer
8.7.6. Presentation Layer
8.7.7. Application Layer
8.8. Mission Planning
8.9. Pilot-In-Command
Questions
9 Control of Air Vehicle and Payload
9.1. Overview
9.2. Levels of Control
9.3. Remote Piloting the Air Vehicle
9.3.1. Remote Manual Piloting
9.3.2. Autopilot-Assisted Control
9.3.3. Complete Automation
9.3.4. Summary
9.4. Autopilot
9.4.1. Fundamental
9.4.2. Autopilot Categories
9.4.3. Inner and Outer Loops
9.4.4. Overall Modes of Operation
9.4.5. Control Process
9.4.6. Control Axes
9.4.7. Controller
9.4.8. Actuator
9.4.9. Open-Source Commercial Autopilots
9.5. Sensors Supporting the Autopilot
9.5.1. Altimeter
9.5.2. Airspeed Sensor
9.5.3. Attitude Sensors
9.5.4. GPS
9.5.5. Accelerometers
9.6. Navigation and Target Location
9.7. Controlling Payloads
9.7.1. Signal Relay Payloads
9.7.2. Atmospheric, Radiological, and Environmental Monitoring
9.7.3. Imaging and Pseudo-Imaging Payloads
9.8. Controlling the Mission
9.9. Autonomy
Questions
Part Four Payloads
10 Reconnaissance/Surveillance Payloads
10.1. Overview
10.2. Imaging Sensors
10.3. Target Detection, Recognition, and Identification
10.3.1. Sensor Resolution
10.3.2. Target Contrast
10.3.3. Transmission through the Atmosphere
10.3.4. Target Signature
10.3.5. Display Characteristics
10.3.6. Range Prediction Procedure
10.3.7. A few Considerations
10.3.8. Pitfalls
10.4. The Search Process
10.4.1. Types of Search
10.4.2. Field of View
10.4.3. Search Pattern
10.4.4. Search Time
10.5. Other Considerations
10.5.1. Location and Installation
10.5.2. Stabilization of the Line of Sight
10.5.3. Gyroscope and Gimbal
10.5.4. Gimbal-Gyro Configuration
10.5.5. Thermal Design
10.5.6. Environmental Conditions Affecting Stabilization
10.5.7. Boresight
10.5.8. Stabilization Design
Questions
11 Weapon Payloads
11.1. Overview
11.2. History of Lethal Unmanned Aircraft
11.3. Mission Requirements for Armed Utility UAVs
11.4. Design Issues Related to Carriage and Delivery of Weapons
11.4.1. Payload Capacity
11.4.2. Structural Issues
11.4.3. Electrical Interfaces
11.4.4. Electromagnetic Interference
11.4.5. Launch Constraints for Legacy Weapons
11.4.6. Safe Separation
11.4.7. Data Links
11.4.8. Payload Location
11.5. Signature Reduction
11.5.1. Acoustical Signatures
11.5.2. Visual Signatures
11.5.3. Infrared Signatures
11.5.4. Radar Signatures
11.5.5. Emitted Signals
11.5.6. Active Susceptibility Reduction Measures
11.6. Autonomy for Weapon Payloads
11.6.1. Fundamental Concept
11.6.2. Rules of Engagement
Questions
12 Other Payloads
12.1. Overview
12.2. Radar
12.2.1. General Radar Considerations
12.2.2. Synthetic Aperture Radar
12.3. Electronic Warfare
12.4. Chemical Detection
12.5. Nuclear Radiation Sensors
12.6. Meteorological and Environmental Sensors
12.7. Pseudo-Satellites
12.8. Robotic Arm
12.9. Package and Cargo
12.10. Urban Air Mobility
Questions
Part Five
Data Links
13 Data-Link Functions and Attributes
13.1. Overview
13.2. Background
13.3. Data-Link Functions
13.4. Desirable Data-Link Attributes
13.4.1. Worldwide Availability
13.4.2. Resistance to Unintentional Interference
13.4.3. Low Probability of Intercept (LPI)
13.4.4. Security
13.4.5. Resistance to Deception
13.4.6. Anti-ARM
13.4.7. Anti-Jam
13.4.8. Digital Data Links
13.4.9. Signal Strength
13.5. System Interface Issues
13.5.1. Mechanical and Electrical
13.5.2. Data-Rate Restrictions
13.5.3. Control-Loop Delays
13.5.4. Interoperability, Interchangeability, and Commonality
13.6. Antennas
13.6.1. Omnidirectional Antenna
13.6.2. Parabolic Reflectors
13.6.3. Array/Directional Antennas
13.6.4. Lens Antennas
13.7. Data Link Frequency
Questions
14 Data-Link Margin
14.1. Overview
14.2. Sources of Data-Link Margin
14.2.1. Transmitter Power
14.2.2. Antenna Gain
14.2.3. Processing Gain
14.3. Anti-Jam Margin
14.3.1. Definition of Anti-Jam Margin
14.3.2. Jammer Geometry
14.3.3. System Implications of AJ Capability
14.3.4. Anti-Jam Uplinks
14.4. Propagation
14.4.1. Obstruction of the Propagation Path
14.4.2. Atmospheric Absorption
14.4.3. Precipitation Losses
14.5. Data-Link Signal-to-Noise Budget
Questions
15 Data-Rate Reduction
15.1. Overview
15.2. Compression Versus Truncation
15.3. Video Data
15.3.1. Gray Scale
15.3.2. Encoding of Gray Scale
15.3.3. Effects of Bandwidth Compression on Operator Performance
15.3.4. Frame Rate
15.3.5. Control Loop Mode
15.3.6. Forms of Truncation
15.3.7. Summary
15.4. Non-Video Data
15.5. Location of the Data-Rate Reduction Function
Questions
16 Data-Link Tradeoffs
16.1. Overview
16.2 Basic Tradeoffs
16.3. Pitfalls of "Putting Off" Data-Link Issues
16.4. Future Technology
Questions
Part Six
Launch and Recovery
17 Launch Systems
17.1. Overview
17.2. Conventional Takeoff XXX
17.3. Basic Considerations
17.4. Launch Methods for Fixed-Wing Air Vehicles
14.4.1. Overview
17.4.2. Rail Launchers
17.4.3. Pneumatic Launchers
17.4.4. Hydraulic-Pneumatic Launchers
17.4.5. Zero Length RATO Launch of UAVs
17.4.6. Tube Launch
17.5. Rocket Assisted Takeoff xxx
17.5.1. RATO Configuration
17.5.2. Ignition Systems
17.5.3. Expended RATO Separation
17.5.4. Other Launch Equipment
17.5.5. Energy (Impulse) Required
17.5.6. Propellant Weight Required
17.5.7. Thrust, Burning Time, and Acceleration
17.6. Vertical Takeoff
Questions
18 Recovery Systems
18.1. Overview
18.2. Conventional Landing
18.3. Vertical Net Systems
18.4. Parachute Recovery
18.5. VTOL UAVs
18.6. Mid-Air Retrieval
18.7. Shipboard Recovery
18.8. Break-Apart Landing
18.9. Skid and Belly Landing
18.10. Suspended Cables
Questions
19 Launch and Recovery Tradeoffs
19.1. UAV Launch Method Tradeoffs
19.2. Recovery Method Tradeoffs
19.3. Overall Conclusions
Questions
20 Rotary-Wing UAVs and Quadcopters
20.1. Overview
20.2. Rotary-Wing Configurations
20.2.1. Single Rotor
20.2.2. Twin Co-axial Rotors
20.2.3. Twin Tandem Rotors
20.2.4. Multi-copter
20.3. Hybrid UAVs
20.3.1. Tilt Rotor
20.3.2. Tilt Wing
20.3.3. Thrust Vectoring
20.3.4. Fixed-Wing Quadcopter Combination
20.4. Quadcopters
20.4.1. Overview
20.4.2. Aerodynamics
20.4.3. Control
Questions
References
1
History and Overview
1.1 Overview
The first portion of the chapter reviews the history of UAV systems from the earliest and crudest "flying objects" through the events of the last decade, which has been a momentous period for UAV systems.
The second portion of the chapter describes the subsystems that comprise a complete UAV system configuration to provide a framework for the subsequent treatment of the various individual technologies that contribute to a complete UAS. The air vehicle itself is a complicated system including structures, aerodynamic elements (wings and control surfaces), propulsion systems, and control systems. The complete system includes, in addition, sensors and other payloads, communication packages, and launch and recovery subsystems.
Finally, a cautionary tale is presented to illustrate why it is important to consider the UAV system as a whole rather than to concentrate only on individual components and subsystems. This is the story of a UAS that was developed between about 1975 and 1985 and that may be the most ambitious attempt at completeness, from a system standpoint, that has so far been undertaken in the UAS community.
It included every key UAS element in a totally self-contained form, all designed from scratch to work together as a portable system that required no local infrastructure beyond a relatively small open field in which a catapult launcher and a net recovery system could be located. This system, called the Aquila remotely piloted vehicle (RPV) system, was developed and tested over a period of about a decade at a cost that approached a billion dollars. It eventually could meet most of its operational requirements.
The Aquila UAS turned out to be very expensive and required a large convoy of 5-ton trucks for transportation. Most importantly, it did not fully meet some unrealistic expectations that had been built up over the decade during which it was being developed. It was never put in production or fielded. Nonetheless, it remains the only UAS of which the authors are aware that attempted to be complete unto itself and it is worth understanding what that ambition implied and how it drove costs and complexity in a way that eventually led the system to be abandoned in favor of less complete, self-sufficient, and capable UAV systems that cost less and required less ground support equipment.
1.2 History
1.2.1 Early History
Throughout their history, UAV systems have tended to be driven by military applications, as is true of many areas of technology, with civilian applications tending to follow once the development and testing had been accomplished in the military arena.
One could say that the first UAV was a stone thrown by a caveman in prehistoric times or perhaps a Chinese rocket launched in the thirteenth century. These "vehicles" had little or no control and essentially followed a ballistic trajectory. If we restrict ourselves to vehicles that generate aerodynamic lift and/or have a modicum of control, the kite would probably fit the definition of the first UAV.
In 1883, an Englishman named Douglas Archibald attached an anemometer to the line of a kite and measured wind velocity at altitudes up to 1,200 ft. Mr. Archibald attached cameras to kites in 1887, providing one of the world's first reconnaissance UAVs. William Eddy took hundreds of photographs from kites during the Spanish-American war, which may have been one of the first uses of UAVs in combat.
It was not until World War I, however, that UAVs became recognized systems. Charles Kettering (of General Motors fame) developed a biplane UAV for the Army Signal Corps. It took about 3 years to develop and was called the Kettering Aerial Torpedo, but is better known as the "Kettering Bug" or just plain "Bug." The Bug could fly nearly 40 mi at 55 mi/h and carry 180 lb of high explosives. The air vehicle was guided to the target by pre-set controls and had detachable wings that were released when over the target, allowing the fuselage to plunge to the ground as a bomb. Also, in 1917, Lawrence Sperry developed a UAV, similar to Kettering's, for the Navy, called the Sperry-Curtis Aerial Torpedo. It made several successful flights out of Sperry's Long Island airfield, but was not used in the war.
We often hear of the UAV pioneers who developed the early aircraft, but other pioneers were instrumental in inventing or developing important parts of the system. One was Archibald Montgomery Low, who developed data links. Professor Low, born in England in 1888, was known as the "Father of Radio Guidance Systems." He developed the first data link and solved interference problems caused by the UAV engine. His first UAVs crashed, but on September 3, 1924, he made the world's first successful radio-controlled flight. He was a prolific writer and inventor and died in 1956.
In 1933, the British flew three refurbished Fairey Queen biplanes by remote control from a ship. Two crashed, but the third flew successfully, making Great Britain the first country to fully appreciate the value of UAVs, especially after they decided to use one as a target and couldn't shoot it down.
In 1937 another Englishman, Reginald Leigh Denny, and two Americans, Walter Righter and Kenneth Case, developed a series of UAVs called RP-1, RP-2, RP-3, and RP-4. They formed a company in 1939 called the Radioplane Company, which later became part of the Northrop-Ventura Division. Radioplane built thousands of target drones during World War II. (One of their early assemblers was Norma Jean Daugherty, later known as Marilyn Monroe.) Of course, the Germans used lethal UAVs (V-1's and V-2's) during the later years of the war, but it was not until the Vietnam War era that UAVs were successfully used for reconnaissance.
1.2.2 The Vietnam War
The first real use of UAVs by the United States in a combat reconnaissance role began during the Vietnam War. UAVs, such as the AQM-34 Firebee developed by Teledyne Ryan, were used for a wide range of missions, such as intelligence gathering, decoys, and leaflet dropping.
During the Vietnam War era, UAVs were used extensively in combat, but for reconnaissance missions only. The air vehicles were usually air launched from C-130's and recovered by parachute. The air vehicles were what might be called deep penetrators and were developed from existing target drones.
The impetus to operations in Southeast Asia came from activities during the Cuban Missile Crisis when UAVs were developed for reconnaissance but not used because the crisis ended before they became available. One of the first contracts was between Ryan and the Air Force, known as 147A, for vehicles based on the Ryan Firebee target drone (stretched versions). This was in 1962 and they were called Fireflys. Although the Fireflys were not operational during the Cuban crisis, they set the stage for Vietnam. Northrop also improved their early designs, which were essentially model airplanes, to jet-propelled deep penetrators, but stuck mostly to target drones. The Ryan Firefly was the primary air vehicle used in Southeast Asia.
A total of 3,435 sorties were flown, and most of these (2,873, or nearly 84%) were recovered. One air vehicle, the TOMCAT, successfully completed 68 missions before it was lost. Another vehicle completed 97.3% of its missions of low-altitude, real-time photography. By the end of the Vietnam War in 1972, air vehicles were experiencing 90% success rates [1].
1.2.3 Resurgence
At the end of the Vietnam War, general interest in UAVs dwindled until the Israelis neutralized the Syrian air defense system in the Bekaa Valley in 1982 using UAVs for reconnaissance, jamming, and decoys. The Israeli Air Force pioneered several UAVs in the early 1980s. In 1982, United States observers noted Israel's use of UAVs in Lebanon and persuaded the Navy to acquire a UAV capability. One of the early UAVs acquired by the Navy was the RQ-2 Pioneer. It was developed jointly by AAI Corporation and Israeli Aircraft Industries and became a very useful air vehicle during Desert Storm for collecting tactical intelligence.
Actually, the Israeli UAVs were not as technically successful as many people believe, with much of their operational success being achieved through the element of surprise rather than technical sophistication. The air vehicle was basically unreliable and couldn't fly at night, and the data-link transmissions interfered with the manned fighter communications. However, they proved that UAVs could perform valuable, real-time combat service in an operational environment.
The United States began to work again on UAVs in August 1971 when the Defense Science Board recommended mini-RPVs for artillery target spotting and laser designation. In February 1974, the Army's Material Command established an RPV weapons system management office and by the end of that year (December) a "Systems Technology Demonstration" contract was awarded to Lockheed Aircraft Company, with the air vehicle subcontracted to Developmental Sciences Incorporated (later DSC, Lear Astronics, Ontario, CA). The launcher was manufactured by All American Engineering (later ESCO-Datron), and the recovery net system by Dornier of the then still-partitioned West Germany. Ten bidders competed for the program. The demonstration was highly successful, proving the concept to be...
