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Does the F-16 have a movable inlet? Everything else like the f15 has it does the f16?

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2 Answers 2

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No it doesn't, and not everything else has movable inlet.

F-16 intake labeled as a simple normal shock diffuser, which keeps weight and costs low

The F-18, F-22, F-35, and Rafale don't have them either. That's because they represent added complexity (more moving parts means more risk of failure), added cost, and added mass, for performances gains that are not worth it anymore. High supersonic flight speeds are no longer required in today's missions. Flying fast was mostly useful to fly away from combat or intercept incoming threats. Missiles have become so fast that you can not outrun them anyway, and radar detection range has increased to the point that you can detect enemy planes sooner, thus not needing Mach 2.5 interceptors. And if you're flying at Mach 1.5, a simple inlet will have some small losses, but you would be better off with a bigger engine than a variable geometry inlet.

F-15 inlet section view

On the other hand, the F-15, Concorde, and SR-71 had movable inlets. Concorde could supercruise at Mach 2.2, the SR-71 was able to reach Mach 3.2. Those are speeds where pressure losses in front of a simple inlet would be enormous due to the shock waves, totally ruining your engine efficiency. The F-15 inlet has two moving plates allowing for 3 weak shocks thus improving greatly the performances at Mach 2.5, with the inlet efficiency going from 0.5 to approximately 0.85 with the addition of the moving plates. As you can see from the diagram below, the difference in efficiency is only meaningful above Mach 1.5. The F-16's requirement was good performances for low price between Mach 0.6 and Mach 1.5 and that's why they did not use variable geometry inlet.

Pressure losses related to number of weak shock

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No it does not. Simple oval shaped tube.

https://upload.wikimedia.org/wikipedia/commons/thumb/8/89/F-16_Fighting_Falcon_air_intake.JPG/706px-F-16_Fighting_Falcon_air_intake.JPG

{Image from Wikimedia}

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    $\begingroup$ Hi, why does it have a vertical bar at the front of the intake? $\endgroup$ Sep 26, 2020 at 13:58
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    $\begingroup$ Structural support, heater, and CCD (Crew Chief Divider). Provides a bit of strength to the opening, prevents ice from building up on it, and prevents a crew chief from going down the pipe in one piece. $\endgroup$
    – WPNSGuy
    Sep 26, 2020 at 19:40

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