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GATE 2019 AE – Question 27

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 · 1 mark · Numerical answer

An airplane with maximum lift-to-drag ratio 18 begins an ideal glide at an altitude of 4 km. What is the maximum horizontal range in km?

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Correct answer: 72 to 72

Explanation

For a steady unpowered glide, tanγ=D/L. Horizontal range is height divided by tanγ, so maximum range is $h(L/D)_{max}=4\times18=72$ km. The result assumes still air and the stated maximum-ratio glide.

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