Question
What is the net upward force on an airplane wing of area 20.1 m2 if the speed of air flow is 302 m/s across the top of the wing and 287 m/s across the bottom? (assume the density of air is 1.29 kg/m3)
Answers
Using Bernoulli equation:
P+(1/2)ρV²+ρgh=constant.
We get
P1+(1/2)ρV1²=P2+(1/2)ρV2²
ρgh being constant.
Thus
P2-P1=(1/2)ρ(V1²-V2²)
=(1.293*g)*(302²-287²)
=111,952 N/m²
The net upward lift
=111,952*20.1 N/m² m²
=2.25*10<sup>6</sup> N
Compare with the weight of a Boeing 747-8:
442,000 Kg= 4.33*10<sup>6</sup> N.
P+(1/2)ρV²+ρgh=constant.
We get
P1+(1/2)ρV1²=P2+(1/2)ρV2²
ρgh being constant.
Thus
P2-P1=(1/2)ρ(V1²-V2²)
=(1.293*g)*(302²-287²)
=111,952 N/m²
The net upward lift
=111,952*20.1 N/m² m²
=2.25*10<sup>6</sup> N
Compare with the weight of a Boeing 747-8:
442,000 Kg= 4.33*10<sup>6</sup> N.
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