The lift equation requires that the dynamic pressure, q, be known. q is equal to 256.35 using σ, found from page 20 of Flight Theory and Aerodynamics.

σ = .7385
V = 320 knots

q = σ V²
       295

q = .7385 * 320²
              295

q = 256.35

L = C_L q S

L = .43 * 256.35 * 1135

L = 125,111.6

Lift should equal weight in un-accelerated flight; although the equation is close, it is not exactly equal to the weight. Varying the airspeed does not give an exact equation where lift equals weight either. When V = 319 knots the answer is slightly less the 124,500 lbs. The dynamic pressure, q, again, needs to be found using the table from page 20.

q = .7385 * 319²
           295

q = 75150.50
         295

q = 254.75

L = C_L * q * s

L = .43 * 254.75 * 1135

L = 124,330.74

Lift still does not equal weight. Therefore, lift is equal to weight between 319 and 320 knots.

At 30,000 Feet:

L= W= 124,500 lbs
C_L = unknown
σ = .3741
V = 436 knots
S = 1135 ft²

L = C_LσV²S
;          295

124,500 = (C_L)(.3741)(436²)(1135)
                               295

124,500 = 80715427.9 * C_L
                    295

124,500 = 273611.62 * C_L

C_L = .46

σ= .3741

V = 436 knots

q = V²
       295

q = .3741 * 436²
          295

q = 241.07

L = C_L q S

L = .46 * 241.07 * 1135

L = 125,862.65

Again, the answer to the equation is larger than the actual weight. Varying the speed by two knots leads to the amount of lift being less than weight being lifted.

σ = .3741

V = 434 knots

q = σV²
      295

q = .3741 * 434²
        295

q = 238.86

L = C_L q S

L = .46 * 238.86 * 1135

L = 124709.30

At 434 knots the lift created is slight low, so the cruise speed would be between 434 and 435 knots. The POH gave a cruise speed of 436 knots at 30,000 ft at this weight, but for lift to equal weight the cruise speed would be closer to 434 knots.