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Civil jet aircraft performance

Civil jet aircraft performance. Resulting force perpendicular to the flight path. Four forces of flight. Net thrust from the engines. α angle of attack V velocity. Newton’s second law. resulting force parallell to the flight path. L=Lift = q · S · C L [N] D=Drag = q · S · C D [N]

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Civil jet aircraft performance

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  1. Civil jet aircraft performance

  2. Resulting force perpendicular to the flight path Four forces of flight Net thrust from the engines α angle of attack V velocity Newton’s second law resulting force parallell to the flight path

  3. L=Lift = q·S·CL [N] D=Drag = q·S·CD[N] q = dynamic pressure [N/m²] S = reference wing area [m²] CL= coefficient of lift CL=f(α,Re,M) CD= coefficient of drag CD = f(α,Re,M) Aerodynamic equations

  4. Reference wing area The area is considered to extend without interruption through the fuselage and is usually denoted S.

  5. Lift versus angle of attack

  6. The ISA Atmosphere From lecture 5

  7. Equations

  8. Lift equation

  9. Drag equation

  10. Drag polar

  11. High speed drag polar

  12. Taxi Take off Climb Cruise Descent Approach and landing Diversion to alternate airport? A flight consists of:

  13. Cruise For an airplane to be in level, unaccelerated flight, thrust and drag must be equal and opposite, and the lift and weight must be equal and opposite according to the laws of motion, i.e. Lift = Weight = mg Thrust = Drag

  14. Range

  15. Range

  16. Breguet range equation For a preliminary performance analysis is the range equation usually simplified. If we assume flight at constant altitude, M, SFC and L/D the range equation becomes which is frequently called the Breguet range equation

  17. Breguet range equation The Breuget range equation is written directly in terms of SFC. Clearly maximum range for a jetaircraft is not dictated by maximum L/D, but rather the maximum value of the product M(L/D) or V(L/D).

  18. Breuget range equation From the simplified range equation, maximum range is obtained from • Flight at maximum • Low SFC • High altitude, low ρ • Carrying a lot of fuel

  19. Range

  20. Endurance Endurance is the amout of time that an aircraft can stay in the air on one given load of fuel

  21. Endurance

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