The Boeing 777 has a wing planform area of 4605 square feet (ft2). Assuming at akeoff weight of 506,000 lb and a takeoff velocity of 160 mi/h, calculate the lift coefficient at takeoff for standard sea-level conditions.
The Boeing 777 has a wing planform area of 4605 square feet (ft2). Assuming at akeoff weight of 506,000 lb and a takeoff velocity of 160 mi/h, calculate the lift coefficient at takeoff for standard sea-level conditions.
For steady, level flight, the weight is equal to the lift.
\[C_{L} = \frac{L}{q_{\infty}S} = \frac{W}{q_{\infty}S}\]
\[ V_{\infty} = 160\left ( \frac{88}{60} \right )=234.7\,ft/s\]
\[ q_{\infty} = \frac{1}{2}\rho_{\infty} V_{\infty}^{2} = \frac{1}{2}\left ( 0.002377 \right )\left ( 234.7 \right )^{2} = 65.45\,lb/ft^{2}\]Therefore,
\[ C_{L} = \frac{W}{q_{\infty}S}= \frac{506000}{\left ( 65.45 \right )\left (4605 \right )} = 0.362\]
