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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
• Federal Air Regulations Part 23
  – Light Planes 12,500 lbs or less
• Federal Air Regulations Part 25
  – Airworthiness Standards: Transport Category
              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
              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, &
• 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.

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