2007_1_55

To be present at the demonstration in May 1964 was to be sure of one thing: The machine worked. It looked like something from a science-fiction movie, a three-foot-square truss of aluminum wire and balsa wood with no moving parts or airfoils, floating silently above the ground. Adjusting electrical controls could make it move up or down or bank in any direction. To some of the observers at the Electron-Atom, Inc., laboratory in Queens, New York, the event seemed almost spiritual.

The man putting the craft through its paces was a renowned aviation pioneer, Alexander de Seversky. He had been involved in aviation for half a century, starting soon after his graduation from Russia’s Imperial Naval Academy in 1914. As a navy flier he was credited with shooting down 13 enemy planes despite having lost a leg in a crash during his first bombing mission. In 1918 he went to the United States as a navalaviation attaché, and as the political situation in Russia worsened, he decided to stay in America.

During the 1920s, as a major in the U.S. Army Air Corps, he was an advisor to Gen. Billy Mitchell, an early advocate of air power. In 1931 he started the Seversky Aircraft Corporation, where he would contribute to the design of a number of innovative aircraft, most notably the P-47 Thunderbolt. He also invented a gyroscopically stabilized bombsight, an in-flight refueling system, and a fuel-carrying wing, and as a pilot he set numerous speed records.

De Seversky was a consummate engineer and showman but a terrible manager, and in 1939 he was ousted from the company by his own trustees, who reorganized it into the Republic Aviation Corporation. He continued his work in experimental aircraft, established himself as a prophet with his 1942 book Victory Through Air Power , and served as an adviser on air-defense strategy after World War II, a job that included attending atomic-bomb tests.

Now, at the age of 69, he was proudly demonstrating his latest invention, the Ionocraft. Like the salesman that he was, he suggested many roles for his creation, as an improvement on the helicopter, a controllable weather-observation platform, an antimissile protection system, and a skyborne antenna or microwave relay. He predicted that future versions would soar to altitudes of more than 50 miles and fly at tremendous speeds.

The craft that inspired such extravagant dreams consisted of a set of negatively charged spikes mounted above a positively charged grid. If the voltage and geometry were right, the spikes would discharge electrons, which were attracted toward the grid by a potential difference of about 30 kilovolts. This current ionized air molecules, which were then pulled toward the grid themselves.

2007_1_56

By itself, this process did not create any lifting force on the craft. But before they slammed into the grid, the ionized air molecules collided many times with neutral air molecules, pushing them downward. Since these molecules had no charge, they were not attracted to the grid, and most of them passed through it. This phenomenon, known as ionic wind, created a downwash of air, just like the rotors of a helicopter, and that was what held the Ionocraft up. A joystick applying different voltages to different parts of the grid could tilt or propel the craft in any direction.

The innovative aircraft had its origins in an entirely different invention, an electrostatic device to reduce air pollution by precipitating gases and particulate matter onto a liquid electrode. While experimenting with this process, de Seversky noticed that it created an air current between the electrodes. “To an old flyer like me,” he told a reporter, “anything that stirs up a wind is a flying machine. So I began to develop the idea.”

In 1964 America was astronaut-crazy, so de Seversky found it necessary to caution: “This is not a spacecraft. It’s an airplane, designed to operate within the atmosphere. But it will be able to do things that no present type of aircraft can accomplish.” With no moving parts, its maintenance would be much simpler than that of any airplane or helicopter. It could take off and land vertically and could hover in place, creep along as slowly as needed, or zoom like a jet. Calculations suggested that it could climb as high as 300,000 feet, much higher than helicopters, which struggle to generate sufficient lift above 20,000 feet. In combat, the open grid would make it less susceptible to enemy fire than conventional aircraft. And the design had no size limit; in fact, the bigger the grid’s surface area, the more energy-efficient it would be, since edge effects would become less important. “We’ll be able to build them as big as a city block,” de Seversky bragged.

The problem with all these schemes, however, was visible in the dangling wire that led to the Ionocraft’s stationary, earthbound power supply. There was no way to put an engine on the craft itself because any apparatus that could maintain the necessary voltage would have made it way too heavy. Even using a mouse as a passenger would have added too much weight. As Hans Fantel of Popular Mechanics wrote, “at present it takes 90 watts (30,000 volts at 3 milliamperes) to fly a two ounce model. Translated into ordinary power-to-weight ratios, this works out to roughly 0.96 hp per pound, as compared with a typical 0.1 hp per pound of helicopter or 0.065 hp per pound for a Piper Cub.”

De Seversky was aware of these obstacles and envisioned a number of possible solutions. These included microwave or laser transmission of energy from the ground, photovoltaic panels, or even a turbine that would use the sun’s heat to boil mercury. His engineers spoke of boosting efficiency by pulsing the power in short bursts, refining the layout of the grid and emitters, and streamlining the craft to reduce drag. With characteristic confidence, de Seversky said, “We hope to fly a model with self-contained power, perhaps by the end of the year. Ultimately, the ionic drive will prove more efficient than either propeller or jet as a method of aircraft propulsion.”

It didn’t happen. Not only did the weight problem prove insurmountable, but other issues became apparent: Could pilots and passengers be safely shielded from the intense voltages? Would there be health consequences from breathing the ionized air? With no wings, how could the Ionocraft glide to a “dead-stick” landing in case of electrical failure? The project was never again pursued by a major company.

Yet the mere fact that it doesn’t work has not kept the Ionocraft from being embraced worldwide. Hundreds of listings on the Internet and in the back pages of magazines offer plans for home-built “UFOs” and “magical flying saucers” using the same technology that de Seversky demonstrated in 1964. Similar devices called “lifters” are a staple of museums, classrooms, and science fairs.

And there is a postscript, of sorts, in the aerospace world. De Seversky’s device and the novelties mentioned above need air to operate, but in space a different form of ionic propulsion has proved valuable. In this method, a beam of atoms, typically of a noble gas, is ionized with electrons, accelerated with a positively charged grid, and ejected through a nozzle. The principle is the same as with a rocket engine ejecting hot gases, but ionized particles can reach much greater velocities because of their high charge-to-weight ratio.

This technology is useful for keeping the microwave antennas of communications satellites pointed toward the earth and their solar panels pointed toward the sun. Adrian Popa, formerly of Hughes Research Laboratories, explains: “The ion engines work well in the vacuum of space because the exhaust beam of ions can reach 100,000 km per hour, so that they use only one-tenth of the amount of fuel that similar chemical thrusters use to provide the required thrust to keep the spacecraft oriented correctly for 15 years.”

Alexander de Seversky died in 1974, having been involved in aviation from the era of frail wood-and-fabric biplanes all the way to jumbo jets and men on the moon. Most of his obituaries mentioned the Ionocraft only briefly, and while it was certainly not one of his more successful projects, it exemplified the wide-ranging imagination and endless passion for improvement that characterized the restless genius’s long career in flight.