We next look at the cruise speed requirement. If q denotes the dynamic pressure at cruise conditions, the required thrust to weight ratio T/W as a function of the wing loading W/S can be calculated as:

The Python implementation once again sweeps a sensible range of wing loading values to build the appropriate constraint diagram:

In [60]: WSlistCR_Pa = np.linspace(Start_Pa,8500,Resolution)

TWlistCR = []

i=0

for WS in WSlistCR_Pa:

TW = q_cruise_Pa*CDmin*(1.0/WSlistCR_Pa[i])

+ k*(1/q_cruise_Pa)*WSlistCR_Pa[i]

TWlistCR.append(TW) i=i+1

WSlistCR_kgm2 = [x*0.101971621 for x in WSlistCR_Pa] figCruise = plt.figure()

Assuming a given target approach speed (which, at the start of the typical final approach translates into a dynamic pressure g^{APP}) and a maximum lift coefficient CA^{PP}achievable in the approach configuration (with the high lift system, if present, fully deployed), the wing loading constraint can be formulated as:

The approach speed constraint will thus impose a right hand boundary in the thrust to weight versus wing loading space at: