# A propeller driven airplane has a gross take-off weight of $4905 \mathrm{~N}$ with a wing area of 6.84 $\mathrm{m}^{2}$. Assume that the wings are operating at the maximum $C_{L}^{3 / 2} / C_{D}$ of $13,$ the propeller efficiency is 0.9 and the specific fuel consumption of the engine is $0.76 \mathrm{~kg} / \mathrm{kW}$ -hr. Given that the density of air at sea level is $1.225 \mathrm{~kg} / \mathrm{m}^{3}$ and the acceleration due to gravity is 9.81 $\mathrm{m} / \mathrm{s}^{2},$ the weight of the fuel required for an endurance of 18 hours at sea level is _____________$\mathrm{N}$ (round off to the nearest integer).

## Question ID - 155473 :- A propeller driven airplane has a gross take-off weight of $4905 \mathrm{~N}$ with a wing area of 6.84 $\mathrm{m}^{2}$. Assume that the wings are operating at the maximum $C_{L}^{3 / 2} / C_{D}$ of $13,$ the propeller efficiency is 0.9 and the specific fuel consumption of the engine is $0.76 \mathrm{~kg} / \mathrm{kW}$ -hr. Given that the density of air at sea level is $1.225 \mathrm{~kg} / \mathrm{m}^{3}$ and the acceleration due to gravity is 9.81 $\mathrm{m} / \mathrm{s}^{2},$ the weight of the fuel required for an endurance of 18 hours at sea level is _____________$\mathrm{N}$ (round off to the nearest integer).

3537

Answer Key : (1440 to 1490) -

1440 to 1490

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The design of an airplane is modified to increase the vertical tail area by $20 \%$ and decrease the moment arm from the aerodynamic centre of the vertical tail to the airplane centre of gravity by $20 \% .$ Assuming all other factors remain unchanged, the ratio of the modified to the original directional static stability ( $C_{N_{\beta}}$ due to tail fin) is____________ (round off to 2 decimal places).