1861 - project
Long before the Wright brothers were sailing in their experimental gliders over the sand dunes of Kitty Hawk, a lonely figure of a scientist was bent over his drafting board in a New York City home putting finishing touches to his design for an aerial machine. At last Mortimer Nelson straightened up. This was it, and at once he dispatched his brain child to the United States Patent Office. Nelson was granted a patent on his flying device on May 21, 1861, and as far as is known, this is the earliest record of an American attempt to build a helicopter.
The New York scientist's aerial invention at first was merely considered an improvement for balloon aircraft. His helicopter device, which he called an "aerial car" was to be used along with a balloon. He explained, "The nature of my ... invention consists in revolving fans, applied to balloons and arranged in such a manner that they can be used for communicating a vertical ascending movement, or a forward propulsion." Later he developed more confidence in his flying machine, so that he felt it could be operated by itself.
Nelson's combination helicopter-balloon aircraft consisted of a body which tapered fore and aft, a pear-shaped rudder at the stern, a parachute canopy over the top of the fuselage and two vertical shafts rising out of the body, each equipped with a pair of rotors. A canvas material or oiled silk was suggested for covering the car, rudder, and parachute. He arranged the rudder in such fashion that it could control the craft's upward, downward, and sidewise flying directions.
Nelson's helicopter had several very advanced engineering features for its day. One of these concerned the rotors. Nelson didn't care particularly how many were placed on his aerial car just so long as there was a minimum of two and that others were added in pairs. The rotors and their shafts could be fixed in an upright position or inclined forward. In describing them, he said, "when the shafts stand vertically ... the revolution of them will tend to raise the balloon or car and that when . . . inclined forward their action on the air will give propulsion to the car." This was anticipating by almost a hundred years another type of aircraft, the convertiplane.
Nelson also realized that the rotors had to spin in opposite directions; otherwise a peculiar force of physics which engineers call "torque" would turn his car in one direction while the fans revolved in another. It is for that reason that Nelson insisted on rotors being installed in pairs.
The other feature which distinguished Nelson's helicopter design was his recommendation for the use of aluminum for all the craft's metal parts. Aluminum was scarcely as well known then as it is now; iron and steel were more commonly used for mechanical apparatus. Nelson was aware, however, that its light weight in comparison to iron and steel would be a great advantage in helping his craft to fly better. In this connection, he wrote, "I have discovered that by making the framework ... of aluminum, a sufficient strength can be obtained, and the great weight usually in such parts so much removed that the sustaining power has not as much weight to lift as would be the case in any engine ... made of iron, steel or other metals." Nelson had again anticipated modern day airplane builders by many decades.
The parachute or awning device which Nelson called for in his design was not meant for safety. This was to be installed over the top of the car at an angle and serve the same purpose as a wing to give the craft lift. According to Nelson's own explanation of this feature, "The parachute ... gives outstanding power to the car in moving through the air and forms a buoyant sail."
Nelson failed to provide one very essential item for his helicopter as described in his patent. He didn't say how the aerial vehicle was to be powered. Perhaps this was because the inventor was aware that some means of propulsion other than the heavy steam engine would be necessary before his craft could fly. Evidence of this is shown by the fact that Nelson conducted experiments on a revolutionary lightweight internal combustion engine. As a result of his efforts along this line, he obtained still another patent on a chemical mixture to be used in his new engine. He called it "carbo-sulph-ethal."
Nelson made some very optimistic claims for his new fuel mixture and engine. Not only would his new engine be far lighter than the conventional steam power unit, but it would also burn a good deal less fuel while producing the same amount of energy. Mortimer Nelson, alas, never transformed his paper-designed helicopter into real life substance.
Frank Ross Jr. "Flying Windmills", 1953