LESSON 11 Chapter 9 Prop Aircraft Applied Performance ANA Chapter 2 *Glider Fact Sheet Due*

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Flight Theory

Chapter 9

Prop Aircraft Applied Performance

Weight

  • We need to take a look at the relationship between power required and thrust required.
  • With an increase in weight there must be an increase in power required and a corresponding increase in velocity.

Configuration

  • The configuration concepts are pretty much the same as the jet performance section with the exception that instead of dealing with thrust required or really the drag curve it must be converted into power required.
  • The basic idea that the parasite drag increases and causes the power required curve to open up at the top.

Altitude Changes

  • In analyzing the power required curve as altitude is increased remember that the TAS goes up and as a result the power required must increase.
  • The L/Dmax tangent point stays the same for each curve its just that the velocity needs to be increased.
  • Supercritical Airfoil
  • Developed by Richard Whitcomb
  • Examples
  • Summary
  • Max specific range is the same at altitude as sea level
  • PR to overcome induced drag varies inversely with V
  • At L/Dmax:

–Best glide

–Max range

  • At PRmin:

–Max endurance

–Min drag

  • For max range at high altitude the same EAS is flown resulting in a higher TAS
  • It takes more power to hold the same EAS at altitude because of less density
  • Best angle of climb Vx is a function of excess thrust
  • Best rate of climb Vy is a function of excess power
  • Best range IAS is higher for a higher gross weight
  • Best range IAS is the same at any altitude for a given weight
  • Best glide ratio is the same regardless of weight
  • Best glide ratio is found at L/Dmax
  • Best rate of climb Vy is at (PA-PR) max
  • Best angle of climb Vx is at or near stall
  • The increase in PR curve for a weigh increase is greater at low speeds because of the increase in induced drag
  • DON’T FORGET ABOUT THE JET ENGINE STUFF!

 

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