AVSC 1010 Lecture 9

# AVSC 1010 Lecture 9 - Lecture 9 How Aircraft Fly Aircraft...

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Lecture 9 How Aircraft Fly Aircraft must be built and flown according to important physical concepts and constraints. Aerodynamics is the study of why and how aircraft fly. This term may make even experienced pilots wince as they think of mathematical formulas and scientific tables which explain the principles of fluid dynamics. This fear is not necessary. Aerodynamics is such a practical application of physical science principles that it is easy to understand if presented correctly by the instructor. This lecture is not meant to be all encompassing or thorough in its treatment of aerodynamics. Further college courses are available which discuss many important laws and principles in great detail. The lecture, should, however, debunk some myths and false beliefs you might have had about how a heavy piece of metal is able to fly in our atmosphere and how you can safely control it. Aircraft fly based on the principles of lift. Lift is a physical vector which is opposite to the force vector called weight. Weight is caused by gravity. Lift must be able to overcome the force of the weight of an object. For example, if an aircraft weighs 50,000 lbs., as in the case of the aircraft I fly, the forces of lift must be equal to or exceed 50,000 lbs. for an aircraft to fly. It took thousands of years for man to understand these basic principles and apply them to aircraft. The most important principle of lift comes through the application of Bernoulli's Principle. Daniel Bernoulli was a Swiss scientist who discovered over 200 years ago that when a volume of liquid's velocity increases, its resulting pressure decreases. He measured pressure flowing through tubes with constrictions, called a venturi, against water flowing through non- constricted tubes. The venturi constriction caused the water to travel faster to make it through the constriction. The faster moving water demonstrated a lower pressure. To achieve this in an aircraft, an airfoil is needed. An airfoil is any shape or surface designed to produce lift. The most common airfoil is the wing of an aircraft. It is curved, similar to the shape of a venturi, to force air on one side of the airfoil to travel faster, while the other side travels at the same speed. Activity: you can demonstrate Bernoulli's Principle through this small experiment. Take a single sheet of thin computer paper, hold it by the corners in front of you, and blow over it. Do not blow under it, but about one inch above the surface. You will notice that the paper seems to be sucked up into the low pressure air above it. This is what happens with the airfoil of an aircraft, only at much higher speeds and is a demonstration of Bernoulli's Principle. Much of the aircraft is designed to take advantage of the airfoil shape, including the wings,

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## This note was uploaded on 09/04/2011 for the course AVSC 1010 taught by Professor Green during the Fall '11 term at Utah Valley University.

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AVSC 1010 Lecture 9 - Lecture 9 How Aircraft Fly Aircraft...

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