A commercial airplane has a total mass of 150,000 lbm and a wing planform area of 1700 ft2. The plane has a cruising speed of 625 mi/h and a cruising altitude of 38,000 ft where the air density is 0.0208 lbm/ft3. The plane has double-slotted flaps for use during takeoff and landing, but it cruises with all flaps retracted. Assuming the lift and drag characteristics of the wings can be approximated by NACA 23012, determine (a) the minimum safe speed for takeoff and landing with and without extending the flaps, (b) the angle of attack to cruise steadily at the cruising altitude, and (c) the power that needs to be supplied to provide enough thrust to overcome drag. Take the air density on the ground to be 0.075 lbm/ft3.

A commercial airplane has a total mass of 150,000 lbm and a wing planform area of 1700 ft2. The plane has a cruising speed of 625 mi/h and a cruising altitude of 38,000 ft where the air density is 0.0208 lbm/ft³. The plane has double-slotted flaps for use during takeoff and landing, but it cruises with all flaps retracted. Assuming the lift and drag characteristics of the wings can be approximated by NACA 23012, determine (a) the minimum safe speed for takeoff and landing with and without extending the flaps, (b) the angle of attack to cruise steadily at the cruising altitude, and (c) the power that needs to be supplied to provide enough thrust to overcome drag. Take the air density on the ground to be 0.075 lbm/ft³.