Question

When an airplane is flying 200 mph at 5000-ft altitude in a standard atmosphere, the air velocity at a certain point on the wing is 273 mph relative to the airplane. (a) What suction pressure is developed on the wing at that point

Answer 1

Answer:

Pressure = $P2=73.13 lbf/ft^2$

Explanation:

The pressure is calculated by Bernoulli's equation.

$P1+\frac{1}{2} dVi^2=P2+\frac{1}{2} dVf^2$

Solving it for P2

$P2=P1 +\frac{1}{2} d(Vi^2-Vf^2)$

Now inserting values

P1 = 0 as it is given that initial point is at atmospheric point.

d= density = 2.05 sl/ft3

Vi = 200 mph = 293.33 ft/s

Vf = 273 mph = 400.4 ft/s

Putting these values

$P2 = 0 + 0.5* 2.05(293.33^2-400.4^2)\\P2=-76sl/ft.s^2$

Changing the units to pounds per square foot

$P2=73.13 lbf/ft^2$