"A Model Mission," Feature Article, December 2004

a model mission

Opening the second century of flight, a team sends a small plane 1,900 miles across the Atlantic—with no one on board.

by Frank Wicks

While the world in 2003 was preparing to celebrate the centennial of the Wright brothers' first flight at Kill Devil Hill on the Outer Banks of North Carolina, a 77-year-old, legally blind experimenter traveled to the Atlantic coast of Newfoundland to launch a flight of his own. Like the Wrights a hundred years earlier, he received little publicity. But his flight may have the kind of significance for this century that the Wrights' achievement had for the last.

Orville and Wilbur Wright put a man in the air on a 600-pound flying machine. Their first flight lasted 12 seconds.
The experimenter, Maynard Hill, sent an 11-pound radio-controlled model airplane on a 38-hour journey from Canada to Ireland. To say "model airplane" makes it sound almost trivial. It was a 1,900-mile flight by an unpiloted aerial vehicle and demonstrated how new technologies can allow unmanned flying machines to perform many types of missions more effectively, cheaper, and safer than human-piloted aircraft.

Hill, who was born in Pennsylvania in 1926, recalls building his first rubber-band-powered model airplane and the thrill of launching a 30-second flight. It was a youth's way of participating in the Golden Age of Aviation, the era of Charles Lindbergh, Jimmy Doolittle, Wiley Post, and Amelia Earhart. The era, too, of Smilin' Jack.

Hill jokes that it caused a lifetime addiction to balsa wood and glue. He continued to build models throughout high school, during his World War II Navy aviation service, and during his years at Penn State, where he received degrees in metallurgy in 1950 and 1951.

Over the years, engines replaced rubber bands, but flight control remained a challenge.

Radio control was an option. It had been pioneered by the twin brothers, Walter and William Good, who were both notable physicists. In 1934 as teenagers, the Goods became the first amateurs to achieve radio-controlled flight.

Maynard Hill in 2003 prepares the aircraft that will cross the Atlantic Ocean under GPS guidance.

They won the Radio Control National Championship in Detroit in 1937, and their entry, the Guff, remained in competition for a decade, until it was retired after winning the nationals again in 1947. The Guff is now on display at the Smithsonian National Air and Space Museum. In 1947, Walter Good was employed by the Johns Hopkins Applied Physics Lab in Maryland. Maynard Hill traveled from Penn State to meet him at his home near Washington. It resulted in a weekend of radio control talk and a lifetime of friendship.

Vacuum tube radio made flight control complicated. Hill said he struggled for two years before he achieved a marginally successful flight with a descending glider by means of stepping the rudder position.

Radio control advanced rapidly after the invention of the transistor in 1947. Transmitters and receivers were developed that provided variable control of the throttle, ailerons, elevator, and rudder.

Maynard also met his wife, Gay, at Penn State. Upon graduation, he took a research position with the Westinghouse Co. in Pittsburgh. He continued to dedicate his spare time to studying radio control and to activities sponsored by the Academy of Model Aeronautics and Fédération Aeronautique Internationale. Much later, he organized the Society for Technical Aeromodel Research, which helped sponsor the trans-Atlantic flight.

In 1960, he moved to the Johns Hopkins Applied Physics Lab, where he could collaborate with Walter Good. Hill's applied research was in high-temperature materials and unmanned aerial vehicles. He later formed his own company for UAV research, design, and development.

Good arranged for Hill to be the chief judge of the World Championships for Aerobatics in 1962. It was held at Kenley Airfield, where 20 years earlier Royal Air Force fighters took off to engage the German bombers during the Battle of Britain.

The event was being held at the height of the Cold War, in the year of the Cuban Missile Crisis. The Soviets continued to lead the United States in space, and technological advances by either side were considered strategic and symbolic victories. Pietrov Velitchkovsky attended the championships wearing a "Hero of the Soviet Union" badge. He already held seven world records, including the top altitude of 7,100 feet.

Hill realized the Soviets were excelling despite the handicap of inferior materials and equipment. He returned to his District of Columbia Radio Control Club and preached that Americans with the advantage of superior resources should be doing much better.

He proceeded to build and fly airplanes to break all of Velitchkovsky's records. He started by almost doubling the record altitude with a flight to 13,320 feet. By 1970, he had established new records for duration, speed, and straight line and closed-circuit distance, along with altitude records for seaplanes and gliders. By 1992, he extended the duration record with a flight of 33 hours and 39 minutes. His son, Scott, flew a model a distance of 808 miles.

Maynard had joked about a trans-Atlantic flight. Then the deployment of the Global Positioning System during the 1990s provided the opportunity: It could guide an autopilot.

The shortest distance across the Atlantic is the 1,900 miles from Newfoundland to Ireland. It was the route of first telegraph between the old and new worlds in 1858. It was first flown in 1919 with a twin engine Vickers bomber by two Royal Air Force officers, Capt. John Alcock and Lt. Arthur Brown. Freezing conditions almost doomed the flight, but Brown maneuvered out onto the wing to clear ice from the engine intake. A monument was constructed in Ireland at the site where they landed.

Executing a Flight Plan

Hill's plan was to begin the flight under manual radio control, transfer to autopilot for the ocean portion, and then back to radio control for landing by another team waiting in Ireland.

International model airplane requirements limited takeoff weight to 11 pounds and engine displacement to 10 cm³ or 0.6 cubic inch. The four-cycle engine Hill preferred had been out of production for two decades, so he advertised on E-Bay to buy a stock of them. A glow plug was replaced by a spark ignition with a Hall effect sensor for timing. A generator was added to eliminate battery weight. Coleman Stove fuel was used for low carbon buildup, with an additive for lubrication.

A smaller carburetor was installed for fuel efficiency. The stock engine is capable of one hp, but only about 0.15 hp was required for level flight. A relatively large wooden propeller of 14-inch diameter and 12-inch pitch resulted in an air speed of 43 mph at 3,900 rpm.

The airplane had a 72-inch wingspan. It looked remarkably conventional except for a sleek fuselage. It was named The Spirit of Butts' Farm, in honor of aviation pioneer Beecher Butts. In 1999, he was a vigorous and inspiring 88-year-old who continued to fly his ultralight aircraft. Beecher made his farm available to Hill for flight testing and more poignantly for handicapped and terminally ill children.

An addiction to balsa wood and glue: Maynard Hill (above) in 1948 and fellow modeler Bud Yenney (in top hat) confer while surrounded by model airplane parts during exam week in their Penn State dormitory room.

The autopilot weighed only a few ounces. It was developed by team member Joe Foster. A challenge was performing a smooth transition from manual to autonomous control and then back to manual for landing. Great circle segments were programmed into a microprocessor and compared with the actual position measured by GPS. Servos moved the throttle for engine speed control, the elevator for pitch and altitude, and the aileron that steered and leveled the wings. A single aileron was used to limit weight.

Almost half of the 11-pound takeoff weight was fuel. Engine speed was programmed to increase moderately during the flight as the airplane became lighter and drag decreased. The programmed altitude of 1,000 feet was measured by an air pressure-based altimeter, and periodically corrected with GPS measurements. The aileron controlled rate of turn, which was measured with a piezoelectric gyro. Operating conditions were transmitted by radio telegraphy. Data included airplane position, altitude, speed and heading, engine speed, and control surface positions.

The Wright brothers made several long trips from Dayton, Ohio, to the Outer Banks to prepare for their epic flight in 1903. Similarly, Hill traveled for three years between Maryland and the coast of Newfoundland.

During his first trip, in 2001, he studied the terrain and met Carl Layden of the Model Aeronautic Association of Canada, who would be the official observer for the Fédération Aeronautique Internationale. A former RAF bomber pilot, Nelson Sherren, learned of the Hills' mission, and offered the use of a large shop with workbenches, tools, an oscilloscope, and computers.

Back in Maryland during the winter and spring of 2002, Hill constructed 21 fuselages and 12 wings. He added red dye to his glue to compensate for his impaired vision. He was invited to demonstrate his construction methods to many radio control clubs.

The design for minimizing engine power and fuel requirements was crucial. It required laminar flow on all surfaces and minimal cross sections. The resulting airplane had a lower drag coefficient than the legendary P-51 Mustang. Hill built a customized dynamometer and spent hundreds of hours measuring engine performance, endurance, and fuel consumption over a variety of conditions.

From the Azores to Ireland

In July 2002. Hill's wife drove him, the airplanes, and the equipment on the six-day journey from Maryland to Newfoundland. The first attempted flight started successfully on radio control, but failed to stabilize when Joe Foster sent the radio signal to transfer control to autonomous flight. They suspected that the airplane was too far out of trim for the transition.

They adjusted for it and the next attempt transitioned smoothly to automatic flight. However, the automatic navigation system flew the plane straight toward the Azores rather than Ireland. The error was corrected over the next three days by Foster and Les Hamilton, who recalculated, resimulated, installed patches, and searched for other problems in 10,000 lines of computer code.

The engine also indicated problems that required further testing. Hill returned to Maryland for more building and testing. Good fortune came in the person of a bright and enthusiastic high school student named Cyrus Abdollahi. He had been doing some UAV research at Johns Hopkins. He was a gifted builder, skilled radio control pilot, and computer whiz, who became a vital contributor to the project in the winter and spring of 2003, and then joined the team in Newfoundland for the summer.

Radio-control mentor: Walter Good, who would become a mentor to Hill, guides the Guff during the 1947 Model Airplane Championships in Minneapolis. He and his brother Bill were pioneers in radio control.

The first attempted flight, on the evening of Aug. 8, 2003, resulted in a smooth departure. The signals from the airplane indicated a flawless flight in terms of course, airplane speed, altitude, engine speed, and trim for the first eight hours. Suddenly, at 430 miles, the signal was lost without warning. Somebody suggested the Bermuda triangle, with its history of mysterious airplane and ship losses, might have a counterpart around Greenland.

The second airplane was launched on the evening of Saturday, August 9. Preparations were rushed to take advantage of favorable weather. The good news on Sunday morning was that the plane was still flying after 560 miles. The bad news was that engine speed and altitude were unsteady. It was indicating slow climbs and rapid descents.

The unsteady flight continued until early Monday morning, when the signal was lost. The prospects were bleak, but Cyrus Abdollahi kept his optimism and continued to monitor from his laptop computer. A few hours later, the signal returned. The engine speed and altitude had stabilized, and the flight was on course. It was later learned that the communications relay satellite had set without downloading the data. When the satellite rose in its orbit, the signal returned.

The fuel situation made the last hour a cliff-hanger. The winds had been less favorable than predicted. There was an estimated 36 hours' worth of fuel with a slightly rich carburetor setting, and the airplane had flown for 37 hours when it came within sight of Dave Brown, who was waiting in Ireland.

Brown had been a member of six U.S. World Champion Radio Control teams. He expertly transferred the airplane to his radio control, cut the engine, and guided it to a dead-stick landing near the monument that marks the 1919 landing spot of John Alcock and Arthur Brown. Dave Brown's wife, Sally, called Gay Hill in Newfoundland. Hill wept on his wife's shoulder with tears of joy.

After seven decades of work, he had broken plenty of records, but this time Maynard Hill had scored his greatest triumph.

Frank Wicks, an aviation enthusiast and pilot, is a frequent contributor to Mechanical Engineering. He is a professor of mechanical engineering at Union College in Schenectady, N.Y.