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GATE 2024 AE – Question 47

Flight Mechanics & Space Dynamics · Airplane performance: drag polar, take-off and landing, climb and descent, ceilings, range and endurance, load factor, turning flight, V-n diagram, winds · 2 marks · Multiple select

Which of the following statements about absolute ceiling and service ceiling for a piston-propeller aircraft is/are correct?

  1. The altitude corresponding to absolute ceiling is higher than that for service ceiling
  2. At the absolute ceiling, the power required for cruise equals the maximum power available
  3. The altitude corresponding to absolute ceiling is lower than that for service ceiling
  4. At the service ceiling, the maximum rate of climb is 50 ft/min

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Correct answer: (A) The altitude corresponding to absolute ceiling is higher than that for service ceiling; (B) At the absolute ceiling, the power required for cruise equals the maximum power available

Explanation

At the absolute ceiling the maximum rate of climb is zero, which means that the minimum power required equals the maximum power available (B). The service ceiling is the altitude at which the maximum rate of climb has dropped to a small value (100 ft/min for a propeller aircraft), so it is lower than the absolute ceiling (A). The service ceiling is defined by 100 ft/min, not 50 ft/min.