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AE 440 Performance Discipline Lecture 9

AE 440 Performance Discipline Lecture 9. Eric Loth For AE 440 A/C Lecture. Some Performance Responsibilities. Define flight requirements with constraint analysis & develop discrete trajectory model for all flight segments Determine fuel for all segments based on engine (from prop.)

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AE 440 Performance Discipline Lecture 9

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  1. AE 440Performance Discipline Lecture 9 Eric Loth For AE 440 A/C Lecture

  2. Some Performance Responsibilities • Define flight requirements with constraint analysis & develop discrete trajectory model for all flight segments • Determine fuel for all segments based on engine (from prop.) • Determine required thrust for mission segments • Determine minimum power/lift. for safety: engine-out, take-off, etc. (to propulsion/aero) • Calculate overall mission performance (alert sub-systems of shortcomings) • Define concept of flight operations (# of flights, airports, etc.)

  3. Typical Mission Profile Main mission flight profile definition (Jenkinson).

  4. Take-Off • Speed definitions (Jenkinson): • VS Stalling speed • V1 Critical power failure speed (decision) • Vr Rotation speed • VLOF Lift-off speed > 1.1VS • V2 Climb speed > 1.2VS

  5. Ground-roll for Takeoff

  6. Transition to Climb • Usually ends at best climb angle.

  7. Important Forces in Climb Geometry for performance calculation (Raymer).

  8. Climb Performance • Best climb rate (jet) graphical method: • Plug in for D, assumes L approx equal to W (small enough climb angle) Graphical method for best climb (Raymer).

  9. Time and Fuel to Climb • Assume linear velocity change for each sectionwhere a = linear constant • Divide climb into smaller segment (less than 5000 ft or 1500 m)

  10. Level Flight • Approx: • Aerodynamicist must provide aircraft S, CL and CD as a function of angle of attack; configurations must provide W (w/ & w/o landing gear, weapons, etc.) • Can re-write to find conditions for minimum thrust (or drag) – see Raymer Eq. 17.19

  11. Range • Missions often specify range – not time, speed or altitude • “Breguet range equation” • “Cruise climb” maximizes range • Break mission into segments to be more accurate • Optimize altitude, speed, wing size, etc. (show this) in order to minimize weight of aircraft and of fuel needed

  12. Turn Performance Level turn geometry (Raymer).

  13. Approach and Landing • VTD = 1.15 VS Approach and landing definitions (Jenkinson).

  14. Ground Roll for Landing • Free-roll (no braking) • Breaking distance:where

  15. Samples of Performance Results from Previous CDRs

  16. Mission Requirements

  17. Mission Profile

  18. Instantaneous Turn for Different Load Factors

  19. Landing and Takeoff Distance Trade Study

  20. Range Trade Study

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