This paper reviews history of unmanned aircraft that are making news today. A team led by the inventor Charles Kettering had developed the airborne contraption, conceived as a top-secret weapon to deliver explosives against enemy troops. The craft was the first practical unmanned airplane. Unmanned aerial vehicles such as this circa 1946 target drone were built by the Radioplane Co. to train antiaircraft gunners during World War II. Weary bombers, such as the radio-controlled B-17G Flying Fortress, were used with small success as flying bombs during the World War II. World War II era target drones preceding unmanned aerial vehicles for surveillance in the coming decades. In 1999, Northrop Grumman boosted its presence in target aircraft further by acquiring Ryan Aeronautical, the company that built the Spirit of St. Louis for Charles Lindbergh in 1927.


In a test that took place several years ago, a small, pilotless biplane took off from Cook Field in Day ton, Ohio. A team led by the inventor Charles Kettering had developed the airborne contraption, conceived as a top-secret weapon to deliver explosives against enemy troops.

That was 1918, toward the end of World War I. The craft was the first practical unmanned airplane.

Its descendants today seem like wonders from the cutting edge of technology. And, in many ways, they are. Their promise for military and peaceful uses seems only to grow. But the Predator and other drones, which have become an integral weapon of air supremacy over Iraq and Afghanistan, have their roots in the very earliest days of conflict in the air.

The first unmanned aerial vehicle took the name of its chief engineer. The Kettering Bug measured just 6 feet across and 5 feet long, was powered by a small two-stroke engine built by the Ford Motor Co., and had enough lift to carry a 250-pound warhead. It was, according to Dik Daso, curator for modern military aircraft at the National Air and Space Museum in Washington, D.C., the first practical example of an unmanned aerial vehicle in the form of an airplane.

The plan was to launch the Bug from. a track, from which it would fly along a straight path toward enemy lines. A counter would keep track of the number of revolutions made by the propeller, and at the desired time, fuel would be cut off from The engine and the Bug would plunge to earth and explode. The Bug had no direct control. An altitude sensor and pneumatic controls based on bellows from a player piano controlled its climb.

The airplane had a tendency to circle in the sky, Daso said. In early tests, the Bug orbited the fields, buzzed the brass in observation stands, and crashed. Eventually, a gyroscope was used to get it to fly fairly straight.

The Army pushed ahead, and later built about 50 of the planes. Toward the end of 1918, aviator Henry "Hap" Arnold, who would later command the U.S. Army Air Forces in World War 11, was dispatched to Europe to convince General Pershing to use the Bug against Germany. The two never got to speak and, in any case, the war ended before the Bug could be deployed in combat.

Yet the Kettering Bug got people thinking, and interest in using unmanned aerial vehicles in combat continued throughout the 20th century. One idea, under the Aphrodite Project during World War 11, was to enlist torn-up B-17 and B-24 bombers that were no longer suitable for combat missions.

A two-nun crew took up the "weary" bomber, packed with explosives, and armed it in the air. The crew then bailed out over British territory and the bomber, equipped with radio control technology developed in the 1920s and 1930s, was steered from another plane that followed, to maneuver it over enemy lines.

The Allies launched 11 of these bombers during the war, but none was very successful, and they were easy to shoot down, Daso said. The project was scrapped when Joseph Kennedy, the older brother of future President John F. Kennedy, and his fellow crewman were killed when the weary bomber they were flying blew up over England. Proponents such as Arnold viewed unmanned aerial vehicles as a way of avoiding the losses sustained by crewed aircraft flying over heavily defended targets, Daso said.

Part of the lineage of unmanned aerial vehicles is their use as targets. Starting in 1939, a company called Radio-plane manufactured its first unmanned aircraft that would be used by the U.S. Army Air Corps to train gunners. "They would fly these big model airplanes-at the time, very high-tech controlled models-and shoot them down," said Doug Fronius, the target programs director for Northrop Grumman Corp. in San Diego. Northrop Grumman acquired Radioplane in 1962, giving it entree to the unmanned aircraft business.




Target Practice

In 1999, Northrop Grumman boosted its presence in target aircraft further by acquiring Ryan Aeronautical, the company that built the Spirit of St. Louis for Charles Lindbergh in 1927. In 1948, Ryan was one of 14 companies to respond to a U.S. Air Force proposal for a jet-powered target aircraft. Ryan won the award and produced the first jet-powered target, the Q2C, which made its first flight in 1952. The Q2C evolved into the BQM34 Firebee, which is in service today.

The real value of air power in World War I was its role in observation and artillery spotting, according to Daso. Unmanned aerial vehicles were ideally suited for this purpose: Cameras were light, and would get lighter.

In October of 1962, the downing of a U2 spy plane prompted a project to put a camera on the Firebee, Fronius said. The program was scrapped when the Cuban Missile Crisis ended shortly thereafter, but the seed was planted to use unmanned aerial vehicles for reconnaissance.

When the United States became involved in the conflict in Southeast Asia, unmanned aerial vehicles were outfitted with film cameras, and also flew electronic warfare missions and electronic surveillance, Fronius said. Real-time delivery of information was not common at the time Although transmitting capabilities existed, more often cameras were retrieved and the film developed later on.

Fronius said the era saw the development of specially designed unmanned aerial vehicles, not merely converted target craft. Some were quite sophisticated, capable of flying at high altitudes and for long periods of time. He added that the industry still did not implement computation al power, digital pay load development that allowed the use of stealth cameras, or the Global Positioning System. Those developments were key to distinguishing later unmanned aerial vehicles from earlier versions.

During the 1980s, the desire to keep pilots out of harm's way and advances in technology came together to focus new attention on unmanned aircraft, Fronius said. In late 2002, the US. Department of Defense issued a "roadmap" for the development of unmanned aerial vehicles over the next 25 years and outlined plans to develop unmanned aerial vehicles by every branch of the service.

Overall, the DOD invested about $3 million in unmanned vehicle development in the 1990s, and another billion dollars since 2000. It plans to invest another $10 billion over the next decade. Today, the number of unmanned aerial vehicles in the field stands at 90; that number could quadruple by 2012. U.S. aerospace companies have unmanned aerial vehicles under development to handle a wide range of missions, those commonly characterized as " the dull, the dirty, and the dangerous"-that is, long-duration flights, sampling of hazardous materials, and exposure to hostile action.



Civilian Flight

Unmanned aerial vehicles may also serve civilian uses. NASA recently concluded a program known as Environmental Research Aircraft and Sensor Technology. The goal of the program, which was started in 1994, was to develop unmanned aerial vehicles and instruments that could be used in science missions too risky for NASA's current science research aircraft.

One of the final steps of the program was to run "detect, see, and avoid" demonstrations to test the feasibility of flying unmanned aerial vehicles in the proximity of other aircraft, with and without transponders.

A follow-up program, called Access Five, will lay the regulatory groundwork that would allow a business case to be made for bringing unmanned aerial vehicles into the commercial market. Besides NASA, the program will also include the Department of Defense, Federal Aviation Administration, and six airframe manufacturers. It will also address technical issues, such as the ability to sense and avoid other aircraft, and secure command and control links, according to Jeffrey Bauer, who will be heading up the program.

Any decision to integrate unmanned aerial vehicles into national airspace will lie with the FAA. Bauer sees the civilian applications of unmanned aerial vehicles as compelling. One obvious application for unmanned aircraft is in homeland defense, and he said there have been discussions with the US. Coast Guard along those lines.

He said that other government agencies, involved with forestry, land resources, and disaster management, have expressed interest in unmanned aerial vehicles. While it is too early to predict exactly where these initial efforts will lead, the groundwork is being laid to take unmanned aerial vehicles to the next level.