Grills on Flanker

[Airpower]

Hi,

Does anyone know what the function is of the grills underneath the large square air intakes of the flanker?

See the pic.

[RecceJet]

I would think it may have something to do with improved air intake characteristics when at higher angles of attack... not sure though. I know the MiG-29 Fulcrum and other aircraft have intake louvres on top of the LEX for on runways to reduce FOD risks, and that is obviously not what this is for - being underneath.

[Webmaster]

The ones below are "floating" auxiliary intake louvres, they open and close under the impact of air pressure differential, not just a high AoA as far as I know. Anyway they let additional air in. Inside, there is a anti-FOD mesh, which if retracted rests on the lower inner surface of the air intake, over the intake louvres. If extended, it blocks (larger) FOD from entering the engine... or well, cuts it into smaller pieces :-)

The grilles on the sides (both outside and inside of each airtake) are "air by-pass outlets" for braking the supersonic air stream (bleed off boundary later)  in the air intake front part. They let air out.