Question

Estimate the force acting on a passenger’s window in a commercial jet aircraft due to air pressure differential.

 

 

Answer 1

In finding out the force on the window of an airplane we assume the following:

 

1. The size of the aircraft window as 10 in × 15 in or 150 in2

2. The aircraft is cruising at a height of 30000 ft where the atmospheric pressure is only 30% of the sea level value

3. The cabin is pressurized to an equivalent of a mountaintop where the air pressure is about 70% that at sea level.

4. The air pressure at sea level is 14.7 psi

 

After making the above assumptions we know that the net pressure acting on the window is the difference between air pressures inside and outside the aircraft.

 

Therefore

Δp = (0.7 – 0.3) × (14.7 psi)

= 5.88 psi

 

We know that the force acting on the window is given by

F = ΔpA

 

where A is the area of the window and ΔPis the pressure acting on the window

 

Hence substituting the values in the above equation we get

F = (5.88 psi) × (150 in2)

= 882 lb

 

Hence recognizing the uncertainty in the estimate of the window area and the pressure differential we estimate the force as approximately 800 lb – 2000 lb.

Hence recognizing the uncertainty in the estimate of the window area and the pressure differential we estimate the force as approximately 800 lb – 2000 lb.