# How much friction is caused by a 10x10 cm window on the side of an airplane?

Say that the airplane is going in 1000 km/h. On the side of the airplane, there is a 10x10 cm window. How much friction would this window cause. For the sake of the calculation, imagine that the airplane is infinitely long. The window is also perfectly level with the rest of the wall, and there is no turbulence on the side of the plane. The outside air is also standing perfectly still. The airplane is travelling at sea level.

I know it is neglectable compared to the turbulence etc. caused by the form of the airplane, but I really need the answer to the question.

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I have to wonder, why do you really need the answer to this question? – David Z Dec 25 '10 at 22:46
If the window wasn't present, what would be? Painted or bare aluminum fuselage wall? Is this all about the friction coefficient of glass? What are you asking? – sigoldberg1 Dec 25 '10 at 22:54
Unfortunatelly, I have no idea what it would be if the window was not present. I guess the friction coefficient of glass would be relevant for answering this question, but I really just need to know the energy loss on glass due to air passing by the glass. The reason for the question is an invention of mine. – David Dec 25 '10 at 23:03
@David: and do you think an answer that assumes the plane being infinitely long will really be relevant for your invention? :-) – Marek Dec 25 '10 at 23:19
Given the vagueness of your question, you really want to ask a practicing aeronautical engineer. This is not really a physics question, more engineering. Try using linked up to find a guy/gal at Boeing, or visit the MIT dept. or NASA or somesuch. You will really need a series of wind tunnel experiments on your invention before you know. – sigoldberg1 Dec 26 '10 at 21:32