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Why does it have such strange intakes?enter image description here

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    $\begingroup$ Please include the image/video source, thanks. $\endgroup$
    – user14897
    Commented May 23, 2018 at 3:19
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    $\begingroup$ @ymb1 It was a YouTube video that came up on autoplay. I didn't keep track of it. I will in the future. $\endgroup$
    – Pilothead
    Commented May 23, 2018 at 19:31
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    $\begingroup$ @Pilothead ok but now that you know what the plane is, it shouldn’t be hard to find a properly licensed image that you can attribute. Also, the video will be in your YouTube history. $\endgroup$ Commented May 24, 2018 at 7:01
  • $\begingroup$ Better view. $\endgroup$
    – mins
    Commented Mar 17, 2023 at 13:46

2 Answers 2

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That's a Polish Air Force MiG-29 "Fulcrum". The strange intakes are to decrease the risk of foreign object damage during rough-field operations.

Edit to clarify: Normally, when the MiG-29 is in flight, the large ramp intakes below the wings are open, providing all the air for the engines, and the louvered intakes on top of the wings are closed. However, if the aircraft is going to be operating from rough fields or flying at very low altitude, the pilot can close the main air intakes. When the main intakes are closed, the louvered auxiliary intakes automatically pop open, so that the air going into the MiG-29's engines comes from above the aircraft, rather than below it; this greatly decreases the risk of the engine eating loose objects on the runway (that, and the fact that the opening a foreign object would have to pass through to enter the engine via an auxiliary intake is much smaller than the opening for the main intakes). As the auxiliary intakes are smaller and at an angle to the airstream, the engines can't get as much air (and, consequently, can't produce as much thrust) when using the louvers as they can when using the main ramps; Mikoyan apparently decided that, for rough-field operations, decreased performance was an acceptable price to pay for a decreased rate of engine object ingestion.

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  • $\begingroup$ Why not have such intakes on large jets also? $\endgroup$
    – Cloud
    Commented May 23, 2018 at 9:39
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    $\begingroup$ Not many jets are designed to take off from grass or gravel. $\endgroup$
    – Hobbes
    Commented May 23, 2018 at 10:27
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    $\begingroup$ @Cloud Cost, weight, maintenance, and lack of operation from rough fields. $\endgroup$ Commented May 23, 2018 at 13:35
  • $\begingroup$ Regarding the thrust question, are the aux intake actually "much smaller" or are they just a lot less efficient at high speeds than the properly shaped and directed main intakes? $\endgroup$
    – Argyll
    Commented Feb 3 at 3:59
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if you look up the top of the leading edge where the wings join with the fuselage, you can see some slats, the engines breathe through these slats when the main intakes are closed, which is mainly during takeoff and landing to reduce the risk of foriegn object damage to the engines. this allows for the russian built mig 29 fulcrum to be able to land on much rougher landing strips

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    $\begingroup$ Aren't the air-intake requirements higher at ground-level because the engines run at full-blast to take-off? If so then it's unusual that they're so small compared to the front intakes. Or are the front intakes bigger because at higher altitude the air is less dense so it needs a bigger cross-section? $\endgroup$
    – Dai
    Commented May 23, 2018 at 17:43
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    $\begingroup$ @Dai Sure, but the risks of ingesting rocks are also higher when the engines are run at full blast to take off! $\endgroup$ Commented May 23, 2018 at 18:12
  • $\begingroup$ @DavidRicherby: Especially since, when the airplane is taking off, it is much more likely to be somewhere where there are rocks to ingest. $\endgroup$
    – Vikki
    Commented May 23, 2018 at 20:50

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