results. Other experimenters, who were convinced that man flight should have wings, worked to .
establish basic principles in aerodynamics, flight stability and control, as well as propulsion. .
Controlled mechanical flight came on August 9, 1884. Charles Renard and A.C. Krebs flew the .
airship "La France- on a closed circuit from Chalais-Meudon to Villacoublay and back in 23 .
minutes. The airship "La France- was powered by a 9 horsepower electric motor that drove a 23ft .
diameter propeller and reached a speed of 14.5 mph. This flight was the birth of the dirigible, a .
steerable, lighter-than-air ship with adequate propulsion. Another important milestone in aviation, .
was the understanding of aerodynamics. Sir George Cayley, a British theorist, was acclaimed as the .
father of aerodynamics. He established a solid foundation of aerodynamic principles that were .
essential to the success of other pioneers. In 1875, Thomas Moy created a large model that had .
twin 12ft propellers with 6 blades each! Interestingly enough these blades could be adjusted to .
produce maximum thrust under certain conditions, an early recognition of the need for changing .
blade pitch. Without a doubt, the most expensive and spectacular project of its time was that carried .
out by Sir Hiram Maxim. His numerous experiments with propellers, culminated in the construction .
of a huge, four-ton biplane in 1890. This contraption was powered by two 180hp steam engines .
that each drove propellers 17ft, 10inches in diameter and weighing 135lbs. The two-blade .
propellers, inversely tapered and squared at the tips 5 ½ ft wide, were made of American Pine, .
planed smooth, covered with glued canvas and stayed to the propeller shafts with steel wire to .
handle the high thrust loads. These massive propellers produced 1,100lbs of thrust each during full .
power while rotating at 425rpm. Maxim's jumbo creation didn't last long however, it jumped the .
test track and suffered extensive damage.
