Calculating Cruise Flight Performance of Jet-Engine Aircrafts

by admin in , , on April 12, 2019

This is a GUI program that calculates the cruise flight performance including: Maximum Level Flight Speed, Minimum Level Flight Speed, Stall Speed, Speed Corresponding to Minimum Drag, Maximum Lift to Drag Ratio, Absolute Ceiling (Maximum Flight Hight corresponding to Minimum Drag) and finally chart presenting Induced Drag, Zero-Lift Drag, Total Drag and position of Vmin, Vmax and VDmin.

To run the program you need to insert the following values: Flight Altitude, Reference Area, Airplane Weight, Engine Thrust, Zero-Lift Drag Coefficient CDo, K constant of CL^2 in the drag polar equation, and the Maximum Lift Coefficient.

The program gives you the maximum hight of a given airplane characteristics and the minimum required thrust for this altitude. The code based on Pamadi[1] and Saarlas[2] equations of performance of jet engine aircraft in cruise flight.

Examples you can try with this program:

A jet-engine airplane weighs 45000 N and has a reference area S of 31 m2. The drag polar is given by CD = 0.014 + 0.038CL^2, CLmax = 1.5, and the engine thrust T = 20,000 a. Determine the maximum and minimum speeds in level flight at sea level and at an altitude of 9000 m. What is the absolute ceiling of this airplane?

Used Terms:

  • L: Lift
  • D: Drag
  • Em: Maximum E(L/D)
  • CD0: Zero-Lift Drag Coefficient
  • K: Weight of CL^2 in Drag Polar (CD = CD0 + K*CL^2)

References:

[1] Bandu N. Pamadi, Performance, Stability, Dynamics, and Control of Airplanes, Second Edition,  at NASA Langley Research Center, Hampton, Virginia.

[2] Maido Saarlas, Aircraft Performance, Department of Aeronautics Engineering at U.S. Naval Academy.

 

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