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Climb Performance

Introduction:

Best Angle-of-Climb:

  • Max excess thrust results in the best angle of climb
  • Occurs at L/Dmax for a jet
  • Occurs below L/Dmax for a prop

Best Rate-of-Climb:

  • Best rate of climb, or Vy, maximizes velocity to obtain the greatest gain in altitude over a given period of time
  • Vy is normally used during climb, after all obstacles have been cleared
  • It is the point where the largest power is available
  • Occurs above L/Dmax for a jet
  • Occurs at L/Dmax for a prop

Best Rate vs. Angle of Climb:

  • Certain conditions will call for a specific climb profile (Vy or Vx)
  • Advantages of Vy:
    • More visibility over the cowling
    • Faster time to climb
    • Increased airflow over the engine while at high power
    • More of a buffer from stall speeds

Factors Impacting Climb Performance:

  • There are several factors which can impact climb performance:
    • Aircraft Weight

      • One of the most basic considerations with regard to aircraft performance is weight, as it is a principle of flight
      • The higher the weight of an aircraft, the more lift will be required to counteract
    • Temperature:

      • Ambient air temperatures impacts your aircraft performance based on their physical properties
      • Engines don't like to run hot and if they do then reduced throttle settings may be required
      • Temperature is also a leading factor in determining the effect of air density on climb performance
    • Air Density:

      • Air density, and more specifically, density altitude, is the altitude which the aircraft "thinks" it is at
      • Performance does not depend on the physical altitude, but rather the density altitude, and the higher the temperature, the higher that altitude
    • Winds:

      • Headwinds increase performance by allowing wind flow over the wings without any forward motion of the aircraft
      • Tailwinds do the opposite
    • Aircraft Condition:

      • Smooth, parasite free wings produce the best lift
      • Anything to interrupt the smooth flow of air or increase drag will require additional forward movement, or thrust, to overcome

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