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A Boeing 777 takes off from Denver Airport (1625 m elevation) where the pressure is 101.8 kPa. Assume that the takeoff speed is 99.4 m/s. This 777 has a takeoff weight of 2,897,229 N and its wing area is 418.9 m2. What is the minimum coefficient of lift needed at the point where

 Oct 15, 2020
 #1
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CL = L / (A * .5 * r * V2 )            L will equal the weight of the plane = 2 897 229 N   

                                                   A = 418 m2

                                                    r=air density   ..  we need the temperature (K)  of the air at 1625 m to calculate density

                                                             using STP and standard lapse rate of 2o C per 1000 ft results in 4.34o C = 277.48 K

                                                           pressure = 101.8 kPa    = 101.8 x 10^3  N/m2   = 101.8 x 103  2kg/(s2-m)  = 10377.17 kg/m2

                                                             using these parameters you can calc   r = 1.27 kg/m3

 

                                                              V = 99.4 m/s

 

 

I find CL = 1.105      (not positive of this answer)

 
 Oct 15, 2020
edited by ElectricPavlov  Oct 15, 2020

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