AE 440 Performance Discipline Lecture 9

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# AE 440 Performance Discipline Lecture 9 - PowerPoint PPT Presentation

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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AE 440Performance 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.)
• 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.)
Typical Mission Profile

Main mission flight profile definition (Jenkinson).

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
Transition to Climb
• Usually ends at best climb angle.
Important Forces in Climb

Geometry for performance calculation (Raymer).

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).

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)
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
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
Turn Performance

Level turn geometry (Raymer).

Approach and Landing
• VTD = 1.15 VS

Approach and landing definitions (Jenkinson).

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