FAR 25.121 Climb, One Engine Inoperative, Approach

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For jet driven aircraft , the thrust to weight ratio to meet FAR 25.121 One Engine Inoperative, Approach Climb requirements is plotted using the following relationship:

 

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The lift coefficient is found from:

 

image\PERF0800_wmf.gif

 

Th e drag coefficient is calculated from:

 

image\PERF0801_wmf.gif

 

The zero lift drag coefficient during approach is dependent on the value of the change in zero-lift drag due to approach:

 

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The 'B' of the aircraft drag polar is calculated from:

 

image\PERF0803_wmf.gif

 

See Matching Plot Guidelines: Jet Driven Airplanes

 

 

For propeller powered aircraft , the weight to power ratio to meet FAR 25.121 One Engine Inoperative, Approach Climb requirements is plotted using the following relationship:

 

image\PERF0804_wmf.gif

 

The lift coefficient is found from:

 

image\PERF0805_wmf.gif

 

The Drag Coefficient is described above.

 

See Matching Plot Guidelines: Propeller Driven Airplanes

 

Note: Equations used in this topic assume the British unit of the parameter used in the program. For the SI unit system, appropriate conversions must be made.