DSI's seem like such an absolutely elegant solution to a problem that has, so far, been solved in a truly overly complicated way.

So, if I'm not missing out on some important small speck of knowledge that complicates DSI's way, way more than being a bump to subsonicize air (of course a slight bit more than that, but you get the idea), then I feel like it is justified for me to get the well-known "this stuff is way too easy to be true"-feeling.

To actually ask the question: Are DSI's really as easy of a solution as they seem right now?

  • 3
    $\begingroup$ I guess you need some serious computing power to calculate it. $\endgroup$ Commented Jun 4, 2018 at 20:15
  • $\begingroup$ Probably for the same reason it took so long to go from a jar of jelly to a squeezable plastic container with a thin slit lid for spreading. It's really not all that obvious until someone thinks of it, and once one person thinks of it everyone else says "That's so obvious! Why didn't I think of that???". $\endgroup$
    – FreeMan
    Commented Feb 1, 2019 at 13:57

1 Answer 1


Designing a DSI inlet is not so simple. It required CFD, a field which had existed for a while but was still viewed with some suspicion in the 1990s. CFD is computationally intensive, so the field has benefited from the massive advances in computing power since the invention of the transistor.

The DSI traces its roots to work done by Lockheed Martin engineers in the early 1990s as part of an independent research and development project called the Advanced Propulsion Integration project. The concept was developed and refined with Lockheed Martin-proprietary computer modeling tools made possible by advances in Computational Fluid Dynamics, or CFD. CFD is the science of determining a numerical solution to the governing equations of fluid flow and advancing this solution through space or time to describe a complete flow field of interest—in this case, the flow field of a fighter forebody, inlet, and inlet duct.


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