Introduction to Unmanned Aircraft Systems

R. Kurt Barnhart, Douglas M. Marshall, Eric Shappee, Michael Thomas Most

• Publisher: CRC Press
• Year: 2016
• ISBN:
  9781482263961
• Edition: 2
• Topic: Politik & Internationale Beziehungen
• Subtopic: Nationale Sicherheit

Introduction to Unmanned Aircraft Systems surveys the fundamentals of unmanned aircraft system (UAS) operations, from sensors, controls, and automation to regulations, safety procedures, and human factors. It is designed for the student or layperson and thus assumes no prior knowledge of UASs, engineering, or aeronautics. Dynamic and well-illustrated, the first edition of this popular primer was created in response to a need for a suitable university-level textbook on the subject.

Fully updated and significantly expanded, this new Second Edition:

• Reflects the proliferation of technological capability, miniaturization, and demand for aerial intelligence in a post-9/11 world
• Presents the latest major commercial uses of UASs and unmanned aerial vehicles (UAVs)
• Enhances its coverage with greater depth and support for more advanced coursework
• Provides material appropriate for introductory UAS coursework in both aviation and aerospace engineering programs

• 
  
  

Introduction to Unmanned Aircraft Systems, Second Edition capitalizes on the expertise of contributing authors to instill a practical, up-to-date understanding of what it takes to safely operate UASs in the National Airspace System (NAS). Complete with end-of-chapter discussion questions, this book makes an ideal textbook for a first course in UAS operations.

1

History

Charles Jarnot, Edited by Benjamin Trapnell

CONTENTS

1.1 The Beginning

1.2 The Need for Effective Control

1.3 The Radio and the Autopilot

1.4 The Aerial Torpedo: The First Modern Unmanned Aircraft (March 6, 1918)

1.5 The Target Drone

1.6 WWII U.S. Navy Assault Drone

1.7 WWII German V-1 Buzz Bomb

1.8 WWII German Mistletoe

1.9 Early Unmanned Reconnaissance Aircraft

1.10 Radar Decoys: 1950s-1970s

1.11 Long-Range Reconnaissance Unmanned Aircraft Systems: 1960s–1970s

1.12 First Helicopter Unmanned Aircraft Systems: 1960s–1970s

1.13 The Hunt for Autonomous Operation

1.14 The Birth of the Twin Boom Pushers

1.15 Desert Storm: 1991

1.16 Overcoming the Manned Pilot Bias

1.17 Amateur-Built Unmanned Aircraft

1.18 Will Unmanned Aircraft Systems Replace Manned Aircraft?

Discussion Questions

1.1 The Beginning

Predating that of manned aircraft, the developmental history of the unmanned version can be argued to begin the real movement forward in man’s age-old desire to rise above the limitations imposed by gravity. To soar with the birds, to see from a vantage known only to the avian world, has been throughout history one of the strongest motivational forces in mankind’s history. Whether in its mythology or in the earliest texts of the renaissance, visionaries have provided glimpses of what might be possible and, in their own ways, began sketching out a road map for future generations of imaginatives to explore and clear even greater paths to their success. Indeed, from centuries past when Chinese kites graced the skies, to the first hot air balloons, unmanned flying craft utilized the technologies of the day to pave a way forward for the development of manned aircraft. And with the development of manned aircraft came the realization that unmanned aircraft were not rendered obsolete. On the contrary, the advancement of systems development of manned aircraft, coupled with advancements in electronic systems, enabled the integration of automation that refined, if not defined, the capabilities of both.

In modern times, unmanned aircraft have come to mean an autonomous or remotely piloted air vehicle that is used to navigate in the air. Even the name assigned to unoccupied aircraft has changed over the years, as viewed by aircraft manufacturers, civil aviation authorities, and the military. Aerial torpedoes, drones, pilotless vehicle, radio-controlled aircraft, remotely controlled aircraft, remotely piloted aircraft, autonomous aircraft, unmanned aerial vehicles (UAVs), and others, are but a few of the names used to describe a flying machine operated without an onboard pilot.

As they progress through this chapter, observant readers will discover that all aircraft, manned or unmanned, followed essentially the same developmental progress involving the development of aerodynamic forces by wings or rotors that offset the weight of the craft, allowing it to fly. This progression involved the development of aircraft control, allowing the pilot to maneuver the aircraft in pitch and bank, effecting safe, aerodynamic control. When more than gliding was desired, the development of the aircraft meant creating suitable propulsion systems; lightweight and powerful enough to propel the craft through the air. With the ability to fly greater distances, the need arose for proper navigational systems, while the development of flight and navigation automation systems reduced the pilot workloads in flight. None of these were trivial matters, as each relied upon the unique adaptation of immature existing technologies to create the new ones that were needed. Advancements in the sciences of aerodynamics, structures, propulsion, flight control systems, stabilization systems, navigation systems, and the integration of all in flight automation systems made the nearly parallel development of manned and unmanned aircraft systems possible. It continues today with refinements made feasible by the advancements in computer technologies and potential energy systems.

In the early years of aviation, the idea of flying an aircraft with no one onboard had the obvious advantage of removing the risk to life and limb of these highly experimental contraptions.* As a result, several mishaps are recorded where advances were made without injury to an onboard pilot. Although such approaches to remove people from the equation were used, the lack of a satisfactory method to affect control limited the use of these early unmanned aircraft. Early aviation developmental efforts quickly turned to the use of the first “test pilots” to fly these groundbreaking craft. Further advances beyond unmanned gliders proved painful, as even pioneer Otto Lilienthal was killed flying an experimental glider in 1896.

As seen in the modern use of unmanned aircraft, historically unmanned aircraft often followed a consistent operational pattern, described today as the three D’s, which stands for dangerous, dirty, and dull. Dangerous means that someone is either trying to bring down the aircraft or where the life of the pilot may be at undue risk operationally. Dirty is where the environment may be contaminated by chemical, biological, or radiological hazards precluding human exposure. Finally, dull is where the task requires long hours in the air, making manned flight fatiguing, stressful, and therefore not desirable.

1.2 The Need for Effective Control

The Wright Brothers’ success in flying the first airplane is more of a technical success story in solving the ability to control a piloted, heavier-than-air craft. Many aviation pioneers either used weight shifting to control their inventions, or aerodynamic design (i.e., dihedral) to stabilize their craft, hoping that a solution would evolve during testing. Dr. Samuel P. Langley, the heavily government-financed early airplane designer competing with those two bicycle mechanics from Ohio, also wrestled with the problem of how to control an airplane in flight. Dr. Langley’s attempts with a far more sophisticated and better powered airplane, however, ended up headfirst in the Potomac river; not once, but twice, over the issue of adequate flight control. After the Wright Brothers taught the fledgling aviation world the secrets of controlled flight, namely, their wing-warping approach to roll control, and a movable horizontal “rudder” for pitch control, aircraft development experienced a burst of technical advancement. Yet it took the tragedy of World War I and the military demands of the 1914–1918 conflict to stimulate the rapid development of a useful tool. All aspects of aircraft design, from relatively advanced power plants, fuselage structures, lifting wing configurations, and control surface arrangements, began to mature into what we see today as the “airplane.” It was in the crucible of “the war to end all wars” that aviation came of age and, along with this wave of technological advancement came the critical but little recognized necessity of achieving effective flight control.

1.3 The Radio and the Autopilot

As is often the case with many game-changing technological advances, inventions of seemingly unrelated items combined in new arrangements to serve as the catalyst for new concepts. Such is the case with unmanned aircraft. Even before the first Wright Brothers’ flight in 1903, the famous electrical inventor Nicola Tesla promoted the idea of a remotely piloted aircraft in the late 1890s to act as a flying guided bomb. His concept appears to have been an outgrowth of his work building the world’s first guided underwater torpedoes, controlled by what was then called “teleautomation,” in 1898. Tesla preceded the invention of the radio in 1893 by demonstrating one of the first practical applications of a device known as a full spectrum spark-gap transmitter. Tesla went on to help develop frequency separation and is recognized by many as the real inventor of the modern radio.

While the electrical genius Tesla was busy designing the first electric architecture for the City of New York, another inventor, Elmer Sperry, the founder of the famed flight control firm that today bears his name, was developing the first practical gyro-control system. Sperry’s work, like Tesla’s, focused initially on underwater torpedoes for the Navy. He developed a three-axis mechanical gyroscope system that took inputs from the gyros and converted them to simple magnetic signals, which in turn were used to affect actuators. The slow speeds of water travel, and weight not being as critical an issue for sea craft, allowed Sperry to perfect his design of the world’s first practical mechanical autopilot. Next, Sperry turned his attention to the growing new aircraft industry as a possible market for his maritime invention, not for the purpose of operating an aircraft unmanned, but as a safety device to help tame unstable manned aircraft, and to assist the pilot in maintaining their bearings in bad weather. Sperry began adopting his system of control on early aircraft with the help of airframe designer Glenn Curtiss. Together they made a perfect team of flyer–designer and automation inventor. Following excellent prewar progress on the idea, the demand during World War I to find new weapons to combat Germany’s battleships combined the inventions of the radio, airplane, and mechanical autopilot to field the world’s first practical unmanned aircraft, an aerial torpedo.

1.4 The Aerial Torpedo: The First Modern Unmanned Aircraft (March 6, 1918)

In late 1916, with war raging in Europe, the U.S. Navy, a military arm of a still neutral country, funded Sperry to begin developing an unmanned aerial torpedo. Elmer Sperry put together a team to tackle the most daunting aerospace endeavor of the time. The Navy contract directed Sperry to build a small, lightweight airplane that could be self-launched without a pilot, fly unmanned out to 1000 yards guided to a target and detonate its warhead at a point close enough to be effective against a warship. Considering that the airplane had just been invented 13 years earlier, the ability to even build an airframe capable of carrying a large warhead against an armored ship, a sizable radio with batteries, heavy electrical actuators, and a large mechanical three-axis gyrostabilization unit, was by itself incredible, but then integrating these primitive technologies into an effective flight profile—spectacular.

Sperry tapped his son Lawrence to lead the flight testing conducted on Long Island, New York. As the United States entered World War I in mid-1917, these various technologies were brought together to begin testing. It is a credit to the substantial funding provided by the U.S. Navy that the project was able to weather a long series of setbacks, crashes, and outright failures of the various pieces that were to make up the Curtis N-9 Aerial Torpedo. Everything that could go wrong did. Catapults failed; engines died; airframe after airframe crashed in stalls, rollovers, and crosswind shifts. The Sperry team persevered and finally on March 6, 1918, the Curtis prototype successfully launched unmanned, flew its 1000-yard course in stable flight and dived on its target at the intended time and place, then recovered and landed. Thus was born the world’s first true unmanned system, or “drone.”

Not to be outdone by the Navy, the Army invested in an aerial bomb concept similar to the aerial torpedo. This effort continued to leverage Sperry’s mechanical gyrostabilization technology and ran nearly concurrent with the Navy program. Charles Kettering designed a lightweight biplane that incorporated aerodynamic static stability features not emphasized on manned aircraft, such as exaggerated main wing dihedral, which increases an airplane’s roll stability at the price of complexity and some loss in maneuverability. The Ford Motor Company was tapped to design a new lightweight V-4 engine that developed 41 horsepower and weighed 151 pounds. The landing gear had a very wide stance to reduce ground roll on landings. To further reduce cost and to highlight the disposable nature of the aircraft, the frame incorporated pasteboard and paper skin alongside traditional cloth. The aircraft employed a catapult system with a nonadjustable full throttle setting.

The Kettering aerial bomb, dubbed the Bug (Figure 1.1), demonstrated impressive distance and altitude performance, having flown some tests at 100 miles distance and 10,000 ft altitudes. To prove the validity of the airframe components, a model was built with a manned cockpit so that a test pilot could fly the aircraft. Unlike the Navy aerial torpedo, which was never put into service production, the aerial bomb was the first mass-produced unmanned aircraft. While too late to see combat in World War I, the aircraft served in testing roles for some 12 to 18 months after the war. The aerial bomb had a supporter in the form of then Colonel Henry “Hap” Arnold, who later became a five-star general in charge of the entire U.S. Army Air Forces in World War II (WWII). The program garnered significant attention when Secretary of War Newton Baker observed a test flight in October 1918. After the war, some 12 Bugs were used alongside several aerial torpedoes for continued test flights at Calstrom Field in Florida.

FIGURE 1.1
U.S. Army Liberty Eagle (Kettering Bug).

1.5 The Target Drone

Surprisingly, most of the world’s aviation efforts in unmanned aircraft after World War I did not pursue weapon platforms like the wartime aerial torpedo and bomb. Instead, work focused primarily on employing unmanned aircraft technology as target drones. In the int...