In deciding upon the shape of a dirigible balloon the chief consideration is to secure an end surface which presents the least possible resistance to the air and also to secure stability and equilibrium. Of course the motor, fuel and propellers are other considerations of vital importance.
The first experimenter on the size of wing surface necessary to sustain a man in the air, calculated from the proportion of weight and wing surface in birds, was Karl Meerwein of Baden. He calculated that a man weighing 200 lbs. would require 128 square feet. In 1781 he made a spindle-shaped apparatus presenting such a surface to the resistance of the air. It was collapsible on the middle and here the operator was fastened and lay horizontally with his face towards the earth working the collapsible wings by means of a transverse rod. It was not a success.
During the first half of the 19th Century there were many experiments with wing surfaces, none of which gave any promise. In fact it was not until 1865 that any advance was made, when Francis Wenham showed that the lifting power of a plane of great superficial area could be obtained by dividing the large plane into several parts arranged on tiers. This may be regarded as the germ of the modern aeroplane, the first glimmer of hope to filter through the darkness of experimentation until then. When Wenham's apparatus went against a strong wind it was only lifted up and thrown back. However, the idea gave thought to many others years afterwards.
In 1885 the brothers Lilienthal in Germany discovered the possibility of driving curved aeroplanes against the wind. Otto Lilienthal held that it was necessary to begin with "sailing" flight and first of all that the art of balancing in the air must be learned by practical experiments. He made several flights of the kind now known as gliding. From a height of 100 feet he glided a distance of 700 feet and found he could deflect his flight from left to right by moving his legs which were hanging freely from the seat. He attached a light motor weighing only 96 lbs. and generating 2-1/2 horse power. To sustain the weight he had to increase the size of his planes.
Unfortunately this pioneer in modern aviation was killed in an experiment, but he left much data behind which has helped others. His was the first actual flyer which demonstrated the elementary laws governing real flight and blazed the way for the successful experiments of the present time. His example made the gliding machine a continuous performance until real practical aerial flight was achieved.
As far back as 1894 Maxim built a giant aeroplane but it was too cumbersome to be operated.
In America the wonderful work of Professor Langley of the Smithsonian Institution with his aerodromes attracted worldwide attention. Langley was the great originator of the science of aerodynamics on this side of the water. Langley studied from artificial birds which he had constructed and kept almost constantly before him.
To Langley, Chanute, Herring and Manly, America owes much in the way of aeronautics before the Wrights entered the field. The Wrights have given the greatest impetus to modern aviation. They entered the field in 1900 and immediately achieved greater results than any of their predecessors. They followed the idea of Lilienthal to a certain extent. They made gliders in which the aviator had a horizontal position and they used twice as great a lifting surface as that hitherto employed. The flights of their first motor machine was made December 17, 1903, at Kitty Hawk, N.C. In 1904 with a new machine they resumed experiments at their home near Dayton, O. In September of that year they succeeded in changing the course from one dead against the wind to a curved path where cross currents must be encountered, and made many circular flights. During 1906 they rested for a while from practical flight, perfecting plans for the future. In the beginning of September, 1908, Orville Wright made an aeroplane flight of one hour, and a few days later stayed up one hour and fourteen minutes. Wilbur Wright went to France and began a series of remarkable flights taking up passengers. On December 31, of that year, he startled the world by making the record flight of two hours and nineteen minutes.
It was on Sept. 13, 1906, that Santos-Dumont made the first officially recorded European aeroplane flight, leaving the ground for a distance of 12 yards. On November 12, of same year, he remained in the air for 21 seconds and traveled a distance of 230 yards. These feats caused a great sensation at the time.
While the Wrights were achieving fame for America, Henri Farman was busy in England. On October 26, 1907, he flew 820 yards in 52-1/2 seconds. On July 6, 1908, he remained in the air for 20-1/2 minutes. On October 31, same year, in France, he flew from Chalons to Rheims, a distance of sixteen miles, in twenty minutes.