Ornithopters, Helicopters and Kites

As the dream of flight lurched toward reality during the nineteenth century, two developments begun centuries earlier came to a climax. One was the failure of attempts to create an ornithopter—a flying machine that emulated birds by having flapping wings—and its cousin, the helicopter, and the other was the development of the kite, which had been around in some form or other for centuries.
In most minds, Italian theorist Giovanni Alfonso Borelli had laid the ornithopter question to rest, yet doubts persisted. New findings about bird flight were casting doubt on Borelli’s conclusions, and new engineering techniques and designs were keeping the possibility of human-powered winged flight alive. One widely publicized plan was that of

Frenchman Jean Pierre Blanchard, who later achieved fame as a balloonist. His machine consisted of an enclosed cabin in which a man’s pedalling with both arms and legs would be amplified by gears and transferred to the flapping wings outside. In 1809, it was widely reported that the Austrian Jacob Degen had successfully flown in an ornithopter. In fact, the reports and the illustrations that accompanied them neglected to mention that Degen and his contraption, an embellishment of Besnier’s design, were tethered to a large hot-air balloon. Degen actually used his wings to provide him just enough lift to rise with the help of the balloon. In this manner, he went balloon-jumping in large leaps on a parade ground, to the delight of onlookers, but only the most gullible would take that for flying.

 Front and aerial views of Jacob Degen’s flying machine as it appeared in the early nineteenth century, but with one important element missing: the huge balloon that actually carried Degen aloft.

Still, Degen had made a contribution: unlike Blanchard and others, his design was actually built and offered some approximation of flight. It also spurred public interest in flight—Degen performed his “act” before appreciative crowds in Paris and Vienna sporadically from 1806 to 1817. Most importantly, however, reports of Degen’s “flight” prompted Sir George Cayley to publish in 1809 the first of his monumental three-part treatise, On Aerial Navigation, a landmark in the history of flight.

In 1810, Thomas Walker’s somewhat more practical design for an ornithopter of Thomas Walker appeared. Though streamlined and mindful of streamlined and mindful of weight limitations, the craft had no chance of ever being airborne. Some elements of its design, however, caught the eye of experimenters in heavier-than-air flight. Although enough experimental and theoretical findings were published throughout the century to show that ornithopters were never going to be feasible flying machines, and the foundation for the airplane had already been laid early in the century, the 1800s saw an ever increasing number of ornithopter designs, particularly from American inventors.

The reason for this was an odd policy of the U.S. Patent Office that granted a large number of patents for such devices; this policy existed because of an assumption that heavier-than-air flight was impossible. (European patent offices were more careful, thus discouraging a great many crackpot designs.) Inventors from weekend tinkerers to Thomas Edison offered a bewildering array of designs, and many were granted patents—but none of these machines flew. A close relative of the ornithopter, the helicopter—a device in which blades rotate in a horizontal plane lifting the device—did see some success in the nineteenth century. As early as 1784, two Frenchmen, Launoy and Bienvenu, built a primitive helicopter powered by a tightly wound cord. Similar success was achieved by Vittorio Sarti in 1828, and by W. H. Phillips in 1842, both of whom used a steam engine as a  power plant.

These machines had no mechanism for control and were less manoeuvrable than balloons. Yet experimenters sensed that this, like the airplane, was an area of great potential. Meanwhile, an age-old device known for centuries, the kite, also underwent some serious study and development. Kites had been used in China since several centuries before Christ, and Marco Polo reported in the fourteenth century that the Chinese had developed kites powerful enough to carry a man aloft. The artistry of Chinese kites has been dazzling through the centuries, and their introduction into Europe by sailors and merchants who brought them back from the Orient delighted both adults and children.

But the development of the kite into a device of interest to aeronautical researchers was the work of a remarkable Australian, Lawrence Hargrave, one of the many extraordinary figures in the early history of flight about whom very little is known. From 1850 to 1915, Hargrave worked in New South Wales, Australia, on many aspects of flight. Far removed from aeronautical activity in Europe and America, and with only a rudimentary grasp of mathematics and physical science, he was a first-class draftsman and mechanic. In 1887, he invented the rotary engine that was later to become a standard design for aircraft power plants, and in 1893 he created the box kite, which was of even more immediate importance.

In 1899, Hargrave attended a meeting of the Aeronautical Society in London and delivered a paper on the box kite. It was immediately obvious to all the attendees, as it had been to Hargrave, that the box kite design was highly adaptable to gliders and eventually to airplanes. Among those who attended was Percy Pilcher, who was later to achieve fame as a glider pilot using Hargrave’s box  kite design. In fact, the designs of early European—but not American—aircraft show the profound influence of Hargrave. The box kite design was eventually abandoned when it was realized that the configuration sacrificed too much manoeuvrability to aircraft stability (and as with the Wrights later, whom Hargrave resembled in many ways, stubborn adherence to principle prevented Hargrave from adapting to new forms, limiting his contribution to aviation history).

Early Helicopter Technology

Helicopter flight was probably the first type of flight envisioned by man. The idea dates back to ancient China, where children played with homemade tops of slightly twisted feathers attached to the end of a stick. They would rapidly spin the stick between their hands to generate lift and then release the top into free flight.

In the western world, the ancient Greek mathematician, physicist, and inventor, Archimedes, who lived and worked in the second century B.C.E. perfected the principle of the rotating screw for use as a water pump. When the screw was rotated inside a cylinder, the screw moved the water in front of it. At the same time, the water resisted and pushed back. This resistance also applied to the movement of screws through air—a type of fluid.

The 15th century Italian Leonardo da Vinci has often been cited as the first person who conceived of a helicopter capable of lifting a person and then experimented with models of his designs. His sketch of the "aerial-screw" or "air gyroscope" showed a device with a helical rotor. The helical surface on his device resembled a helicopter and was made from iron wire and covered with linen surfaces made "airtight with starch."

In 1483, Leonardo da Vinci of Italy sketched the most advanced plans of the period for an aircraft that was really a helicopter.  His theory for "compressing" the air to obtain lift was substantially similar to that of the modern helicopter.

Leonardo planned to use muscle power to revolve the rotor, although such power would never have been sufficient to operate a helicopter successfully. His notes implied that his models flew, but from his sketch, there was no way to deal with the torque created by the propeller. Although he had undoubtedly identified the concept of a rotary-wing aircraft, the technology needed to create a helicopter had not yet been produced. His drawings date to 1483, but they were first published nearly three centuries later.

A large number of fanciful inventions surfaced between the time of Leonardo and the 20th century. These helped advance the knowledge of vertical flight, but they all lacked sufficient power to achieve flight and were too bulky and heavy. Serious efforts to create a real helicopter did not occur until the early years of the 20th century.

In 1754, Mikhail Lomonosov, the "Father of Russian Science," suggested that a coaxial rotor machine could be used to lift meteorological instruments. He developed a small coaxial rotor modelled after the Chinese top, but powered by a wound-up spring that he demonstrated to the Russian Academy of Sciences in July 1754. The device may have climbed and flown freely or it may have been suspended from a string.

J.P. Paucton seems to have been the first European to propose the helicopter as a man-carrying vehicle. In his Theorie de la vis d'Archimedes, he described a man-powered machine called a Pterophere with two airscrews—one to support the machine in flight and the second to provide forward propulsion.

In 1783, the French naturalist Launoy, with the assistance of his mechanic Bienvenu, used a version of the Chinese top in a model consisting of two sets of rotors made of turkey feathers that rotated in opposite directions. This "counter-rotation" solved the problem of torque since the forces created by each rotor cancelled each other out. They demonstrated the model, which resembled Lomonosov's model in principle, in 1784 before the French Academy of Sciences and succeeded in achieving free flight.

Launoy and Bienvenu designed a version of the Chinese top that consisted of two sets of rotors made of turkey feathers that rotated in opposite directions, which solved the problem of torque.

George Cayley, who, as a young boy, had been fascinated by the Chinese top, built his earliest vertical-flight model, a twin-rotor helicopter model in 1792 and described it in On Aerial Navigation in 1796. It was very similar to Launoy and Beinvenu's model. By the end of the 18th century, he had constructed several successful vertical-flight models with rotors made of sheets of tin and driven by wound-up clock springs. In a scientific paper published in 1843, Cayley described a relatively large vertical flight aircraft design that he called an Aerial Carriage. However, his device remained only an idea because the only engines available at the time were steam engines, which were much too heavy for successful flight.

In 1843, Sir George Cayley of Great Britain drew up plans for this "aerial carriage" that used rotors on opposite sides to counteract torque. This configuration is sometimes still used.

The lack of a suitable engine stifled aeronautical progress, but the use of miniature lightweight steam engines met with limited success. In 1842, the Englishman W.H. Phillips constructed a steam-driven vertical flight machine that ejected steam generated by a miniature boiler out of its blade tips. Although impractical to build at full-scale, Phillips' machine marked the first time that a model helicopter had flown powered by an engine rather than by stored energy devices such as wound-up springs. He exhibited his model at the Crystal Palace in London in 1868.

Another idea at this time, documented by Octave Chanute in Progress in Flying Machines, was a model built by Cossus of France in 1845. It had three rotating aerial screws that were moved by steam power. Chanute also mentioned a device by a Mr. Bright that consisted of axles that were suspended beneath a balloon and rotated in opposite directions.

This 1845 design for a primitive helicopter by Cossus appeared in Octave Chanute's Progress in Flying Machines. The rotating screws were to be moved by steam power.

A U.S. Confederate soldier, William Powers, designed an attack helicopter in 1862 that made use of Archimedes' screws powered by a steam engine that was to propel it vertically and forward. He intended to use it to break the Union's siege of the southern ports. He constructed a non-flying model but did not construct a full-size craft.

In France, an association was set up to assemble the many helicopter models and designs that had proliferated during the 1860s. In 1863, the Vicomte Gustave Ponton d'Amecourt built a model helicopter with counter-rotating propellers and a steam engine. He patented it in France and Great Britain and exhibited it at the 1868 London Aeronautical Exposition. This machine failed, but another model using spring propulsion had better luck. He called his machines "helicopteres," which was derived from the Greek adjective "elikoeioas," meaning spiral or winding and the noun "pteron," meaning feather or wing.

Gustave Ponton D'Amecourt constructed, in 1865, an aerial screw machine that worked by steam. It was exhibited at the London Aeronautical Exposition in 1868.

In 1870, Alphonse Penaud constructed several model helicoptére that he fashioned after the Chinese top. They had two superimposed screws rotating in opposite directions and set in motion by the force of twisted rubber bands. Some of his models rose to more than 50 feet (15 meters). In 1871, Pomes and De la Pauze designed an apparatus that had a rotor powered by gunpowder, but it was never built.

Penaud's flying screw, which the French called a "Helicoptere," consisted of two superimposed screws rotating in opposite directions and powered by the force of twisted rubber bands. This design inspired by the Wright brothers when they were boys.

In 1877, Emmanuel Dieuaide, a former secretary of the French Aeronautical Society, designed a helicopter with counter-rotating rotors. The engine boiler was on the ground and connected to the machine by a flexible tube. Also that year, Melikoff designed and patented a helicopter with a conical-shaped rotor that doubled as a parachute for descent.

The invention of Dieuaide, at one time secretary of the French Aeronautical Society, consisted of two pairs of square vanes set a various angles to the line of motion so as to vary the pitch and rotated in opposite directions by gearing. It had a steam engine.

In 1878, Castel, a Frenchman, designed and built a helicopter driven by compressed air with eight rotors on two counter-rotating shafts. This model did not work, but a smaller one built by Dandrieux between 1878 and 1879 and driven by elastic bands did.

Also in 1878, Enrico Forlanini, an Italian civil engineer, built another type of flying steam-driven helicopter model powered by a 7.7-pound (3.5-kilogram) engine. This model had two counter-rotating rotors and rose more than 40 feet (12 meters), flying for as much as 20 seconds.

This design by Melikoff in 1877 consisted of a screw parachute. It would be rotated by a gas turbine. It was designed to carry a man.

In the 1880s, Thomas Alva Edison experimented with small helicopter models in the United States. He tested several rotor configurations driven by a gun cotton engine, an early form of internal combustion engine. However, a series of explosions that blew up part of his laboratory deterred him. Later, Edison used an electric motor for power, and he was one of the first to realize from his experiments that a large-diameter rotor with low blade area was needed to give good hovering efficiency. Edison's scientific approach to the problems of vertical flight proved that both high aerodynamic efficiency of the rotor and high power from an engine were required for successful vertical flight.

At the end of the nineteenth century, inventors had not solved the inherent aerodynamic and mechanical complexities of building a vertical flight aircraft. The hundreds of failed helicopter inventions had either inadequate power or control or experienced excessive vibration. Some of the better-designed early helicopters managed to hop briefly into the air, but they did not attain sustained flight with control. Steam engines were just too heavy for a full-scale helicopter. Not until the internal combustion engine was invented and became available could inventors develop full-sized models.

A number of technical problems challenged the early developers of helicopters. These included limited knowledge of the aerodynamics of vertical flight, the lack of a suitable engine, the inability to keep the weight of the structure and engine low enough, the problem of excessive vibration, the inability to deal with the torque created by the propellers, and the inability to achieve adequate stability and control.