Technological Institute of Aeronautics Requirement 4: Missed Approach Climb

 Background

Climb Gradient

JAR 25.121 Climb: One-engine-inoperative.
(d) Discontinued Approach. In a configuration in which VS does not exceed 110% of the VS for the related all-engines-operating landing configuration, the steady gradient may not be less than
      2·1 % for two-engined airplanes,
      2·4 % for three-engined airplanes, and
      2·7 % for four- engined airplanes, with -
(1) The critical engine inoperative, the remaining engines at the available take-off power or thrust;
(2) The maximum landing weight; and
(3) A climb speed established in connection with normal landing procedures, but not exceeding 1·5 VS.
(4) Landing gear retracted.*

 * Number (4) of § 25.121 (d) exists only in JAR 25 but not in FAR Part 25.

 Equation

The missed approach is similar to the second segment situation where one engine of the aircraft is inoperative. The thrust of the remaining engine(s) has to be enough to climb again as required. The second segment climb equation is expanded by the mass ratio determined already in the landing field calculation:

The climb gradient can simplified similar to the second segment:

Lift to Drag Ratio

• Oswald's airplane efficiency factor e is 0.7,
• wing aspect ratio A is given or taken from statistics,
• drag coefficient at zero lift c_{D, 0} is assumed to be 0.02,
• landing gear drag coefficient c_{D, gear} is 0.015,
• slat drag coefficient c_{D, slat} is neglected and set to zero,
• flap drag coefficient c_{D, flap}:
  for c_L = 1.3 : flap deflection 15° => c_{D, flap} = 0.01
  for c_L = 1.5 : flap deflection 25° => c_{D, flap} = 0.02
  for c_L = 1.7 : flap deflection 35° => c_{D, flap} = 0.03 .

background of mass relation   statistics of aspect ratio   next: cruise requirements

 Results compared

Back to Second segment climb   Back to design diagram