Graziano & Raulin
Research Methods (9th edition)
Jean Pierre Francois Blanchard (1753-1809) was a French balloonist, who was one of the first to ascend in a hot air balloon. He became famous and rich with his aerial exhibitions.
In 1785, 117 years before the Wright Brothers’ heavier-than-air flights, Blanchard was the first to fly a balloon across the English Channel. Around 1793, he demonstrated a successful parachute and may have been the first person to do so.
Blanchard was mentioned in Chapter 2 of this text, because it was his wing designs that led to the creation of the propeller, a device critical for the Wrights’ later success. Blanchard worked on his flying machines more than half a century before the theory of lift and thrust were developed. Without the advantage of theoretical understanding of principles, Blanchard had to rely mainly on trial-and-error, and he did so with enthusiasm. Before he began to use balloons, Blanchard believed he could lift himself with human-operated wings, and then propel himself through the air using the same lifting apparatus. He never succeeded with his heavier-than-air apparatus, but by 1797, his work on wing designs for lift and forward propulsion, were major contributions to the later design of the propeller.
Aerodynamically, a propeller is similar to a wing, because both are forms of airfoils. The shape of the airfoil is such that, when moved through air, forces perpendicular to the surface of the airfoil are created. An airplane’s wing has a curved upper surface and a relatively flat bottom surface, resulting in a faster flow of air particles across the top. The speed differential, according to Bernoulli’s Principle, causes more pressure (force) against the bottom surface than the top, resulting in lift. Lift supports the craft in the air. With the propeller, the force (again perpendicular to the surface of the device) is thrust, which moves the craft forward. Thus, wing design helped to establish the structure and function of propellers.