What are the holes in aircraft glass?

Dear friends and followers. Today s question is another absolute classic passenger question: Joe why is that a little hole in the cabin window ？I m pretty sur...

Nov 24,2021 | Janet

Dear friends and followers.

Today's question is another absolute classic passenger question:

Joe why is that a little hole in the cabin window ？I'm pretty sure that many of you have seen a little hole in the window before and might have asked the same question.So let's get started！ After takeoff and June climb, the outside air pressure is aneight constant for whilst the air pressure within the cabin isn't a constant rise,created by the aircraft's bleed and air conditioning system. Otherwise it would have trouble breathing to the flight.

Building Glass

Now ,due to the big difference between the ambient air pressure in the cabin and the low-pressure outside, there is a lot of physical stress on the cabin hall and especially on the windows. Now if we take a closer look at the cabin windows. You'll see they are made up out of three separate window panes one outer and one middle pane. Which share the same window frame and one inner pane.

Now if you look at your windows installed in your home ,you'll see they're also made up out of at least two window panes of glass with a transparent gas in between acting as a temperature barrier ,which will stop condensation on the inner side of the window.

Now the same in the airplane, but without the special gas in between,because the air pressure difference and the temperature changes are so much higher than in your home. Engineers had to come up with an idea to prevent the windows from fogging and freezing up. So they did decided to leave a little air gap in between the two panes, but air has the physical effect of expanding and shrinking either due to poor air pressure or temperature changes which could damage the window. So that's where the little hole comes to play it acts as a bleed whole balancing of the air

pressure differences in the gap between the two panes letting the outer pane deal with the air pressure, physical stress, and being directly exposed decreasing temperatures whilst the middle pane acts as a fail-safe window in case the outer pane gets damaged and breaks.It's pretty ingenious if you ask me.

So what about the inner pane to be straight with you? It's just a plastic preventing the passages from damaging the middle pane. By the way, there is no seal in between the inner and the middle pane the cabin air flows around the inner pane.

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