flight
...luid flows over a surface, the fluid molecules closest to the surface cling microscopic roughness of the surface. As you move away from the surface, there is a small transition distance where the fluid’s viscosity limits the change in speed of the adjacent molecules, until at a certain distances the fluid is at full speed. (Paper airplane aerodynamics www.geocities.com/capecanaveral/1817/paene/html) Osborne invented a number that was devised which gives the importance of viscosity in fluid flow. It’s called the Reynold’s number. Reynold’s number =9340 for air so you’d take 9340x velocity relative to surface (mph) x length over surface fluid has traveled feet. This determines how influential the viscosity is. Secondly, Swiss mathematician and physicist, Daniel Bernoulli, created Bernoulli’s principle in 1738. It stated the concept that as the speed of a moving fluid increases, the pressure within the fluid decreases. An increase in the fluid’s speed must be matched by a decrease in pressure. The mathematical theorem for the Bernoulli affect is p + ? p V2. One source said, “the principle also applies to the spinning of a baseball” (Simons, 1989, pg. 23) The rotation causes an additional velocity component to be sent in the direction of rotation. Because of all that, the total velocity around the ball is higher on one side then the other. This is an example of how Bernoulli’s principle works. Next, supersonic flight includes speeds from mach one to five: above five are considered hypersonic. The bell X-1 rocket plane first achieved supersonic flight in 1947. “Many attempts had been made before that but when the plane ran against the sound barrier the pilot often lost control when the shock waves built up against the surface” (Compton’s 1994). Mach one is considered traveling below the speed of sound (subsonic). Mach two is traveling twice the speed of sound (supersonic). All aircraft’s that are traveling at supersonic or hypersonic speed create a shock wave that represents a big change in the air pressure. The shock is in reality a cone shape (a mach cone). The mach cone at mach 1 is more of a hill but as the mach numbers increase, the cone gets pushed back to more of a mountain. As the wave gets closer to the wing, the drag increases dramatically. When you are at subsonic mach numbers, the drag is increased as a result of small wing span or low aspect ratio. “Low aspect ratio is the ratio of span to mean chord of an airfoil” (Reithmaie...