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AA311.Lecture1 - AA 311 Lecture 1 Introduction Units...

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AA 311 Lecture 1: Introduction; Units; Airplane Anatomy Reading: [1] Chapter 1, Chapter 2.4, Chapter 2.6. When asked about the beginning of human flight, the first thing that comes to our mind is the historic achievement of the Wright brothers on December 17, 1903, when their Wright Flyer I (shown in Figure 1) lifted off the sand dunes of Kill Devil Hills by its own power, carrying Orville Wright into the air in sustained flight for approximately 12 seconds. The result was a culmination of efforts by many ingenious researchers and scientists over the centuries that lead to the successful controlled flight of the first aeroplane. Atmospheric flight vehicles can be categorized into two very distinct types: 1. Lighter-than-air vehicles, such as blimps and balloons, and 2. Heavier-than-air vehicles, such as airplanes and gliders. (a) From [1]. (b) From [1]. Figure 1: The Wight Flyer. The first human flight actually occurred on November 21, 1783, when a hot-air balloon carried Pilatre de Rozier and Marquis d’Arlandes into the air, and flew about 5 miles across Paris. The hot-air balloon is a lighter-than-air vehicle, where the necessary lift force — to keep the vehicle in the air — is generated by buoyancy. Heavier-than-air vehicles, on the other hand, need an alternative source of lift force, as the buoyant force is typically negligible, and is not sufficient to overcome gravity. Referring to Figure 2a, the four fundamental forces acting on a flight vehicle are Weight (due to gravity). Thrust (force generated by the propulsion system). Lift (an upward force that keeps the airplane in the air by countering gravity). Drag (aerodynamic resistance that has to be countered by thrust). The fundamental problem of heavier-than air flight is to generate the necessary lift force and thrust force to reach a force balance for steady and sustained flight. Early experimentalists tried to solve the problem by inventing machines that would mimic the flight of birds, using flapping wing mechanisms. A common theme in their approach was that the same mechanism was used to generate lift and propulsion (Figure 2b). 1
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(a) From [3]. (b) From [3]. Figure 2: In an airplane, the mechanism for of propulsion (the engine) is separated from the mechanism of lift (wings). Birds use wing strokes for both propulsion, and lift. Birds have evolved to be very efficient flyers that can propel themselves through the air effortlessly. How- ever, early aviators did not have the technology to fabricate machines with high enough power to weight
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