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Design Chapter 8 First Half Design Requirements and Specifications • Payload • Range • Cruising Speed • Takeoff & Landing Distance • Ceiling Economic Requirements • Cost • Fuel Consumption • Maintainability • Reliability Airworthiness Requirements • Design must meet FAA standards for safety • FAA is responsible for safety of all civil aircraft • Federal Air Regulations Part 23 – Light Planes 12,500 lbs or less • Federal Air Regulations Part 25 – Airworthiness Standards: Transport Category Airplanes Design Phase • Conceptual Design – General concept of what the plane will look like – Jet/prop, single/multi, high wing/low wing, fixed gear/retractable gear • Preliminary Design – The aerodynamic design, consideration of aerodynamics in arriving at overall configuration Design Phase • Detail Design – The final stage – Design of supporting structure – Modification to preliminary desugn decisions Initial Conception • Step one: Study the design & specifications • Step two: Determine what characteristics to shoot for in payload, speed, range, takeoff distance, landing distance, climb rate, & ceiling. Terms • Wing loading – the ratio of weight to wing area – the average weight that each unit of wing area must carry – W/S • Power loading – the amount of power per unit of weight – P/W Fuselage Design • The fuselage design shape for aerodynamic efficiency (low drag) • Optimum shape for a typical four-place light plane is a fuselage length of approx. 24 feet with a diameter of 8 feet • Figure 8-1 p. 217 • Figure 8-2 p. 218, figure 8-3, 8-4 Fuselage Design • Tandem/ Side by side • Seat pitch • Aerodynamic stand point • Cabin Height Wing Design • High/ Low configuration • High Wing – better L/D ratio, lateral stability, shorter landing distance, better crash & fire protection • Low Wing – better landing gear support, roll maneuverability, easier refueling, shorter takeoff distance, crash energy absorption Planform Selection • Planform • figure 8-7 combination of rectangular & tapered wing planform • Optimum airfoil – low drag coefficient, min. drag at design lift coefficient, max. lift coefficient, pitching moment coefficient, sufficient thichness for spar, fuel, & landing gear Increased Thickness • Increases maximum lift coefficient • Increase drag coefficient • Provides greater space for structure and fuel Increased Camber • Increases design lift coefficient • Increases pitching moment • Increases lift coefficient Power Plant Selection • Power to weight to ratio • actual engine dimensions • location of the carburetor • best choice of prop • cowling design Quiz on Chapter 8 Quiz on chapter 8 • List and explain two design obstacles to study when designing a plane.