A Boeing 727-200 jet transport has wing plan form area Ap = 148 m², and aspect ratio A, = 6.5. Stall speed at sea level for this aircraft with flaps up and a gross weight, W of 667 kN is 78 m/s. Below M=0.6, drag due to compressibility effects is negligible. Drag at zero lift, Coo for the aircraft is 0.0182. Assume sonic speed, a at sea level is 340 m/s. Answer the following: 1. Evaluate the performance envelope for this aircraft at sea level by plotting drag force Fo versus speed, between stall and M = 0.6. (10 marks) 2. From the graph determine the optimum cruise speed at sea level conditions. (1 mark) 3. Comment on stall speed and optimum cruise speed for the aircraft at 9144 m altitude on a standard day. (4 marks) (Ps.level=1.226 kg/m³, Pat. = 0.46 kg/m²; for steady level flight Fo= 2 p V2 A C₁ = Thrust (T) and F₁ = 1/2 p V2 A C₁ = Weight (W); Co Coo + C/||A₁; M = V/a}.