I see several questions on the NACA ducts found on airliners Example 1, Example 2, Example 3 and I was wondering how much drag is normally generated by these inlets? As they take in air, I imagine there must also be some momentum losses.

I found this source, which gives a nice overview of the distribution of inlet drag for varying locations, but it's hard to judge the total amount from it.

inlet drag sensitivity to location

Image source

Is the inlet drag a significant portion of the total drag? What percentage of the total drag is it?


1 Answer 1


The legendary Fluid Dynamic Drag by Sighard Hoerner contains all the numbers you need. Chapter 9-E should be what you're looking for.


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