f-4 phantom II air intake

[jcpuccio 0]

Does anyone here, (maybe a Phantom pilot) know what purpose that small piece of metal next to the air intakes had???....it looks like it's almost made to cover up the air intake from air flow but that couldn't be i don't think...also, does it move at all?...thanks - jcpuccio

[FastCargo 412]

That's not an F-4, it's an F/A-18F Super Hornet.

 

Secondly, can you point out the specific intake and specific 'piece of metal' you are talking about?

 

FC

[Hokum 0]

I think he means this bit, i think it's to slow air intake speed at MACH?

[Gr.Viper 131]

Possibly serves to separate normal intake airflow from the air streaming along the nose. At least on Flogger it does just that.

[+aleks 9]

it was movable and served to reduce the effective airtake aperture, in accordance of the air speed.other aircrafts such as f104, mirages and mig 21 used cones or semi-cones that moved in front in high speds and back to low speeds, for the same reason

[ezlead 42]

Turbojet and turbofan engines cannot effectively use supersonic air. The front blades on the compressors set up shockwaves and the engines compressor stall or flameout.

The air coming in the intake has to be slowed to subsonic speed for the engines to use it effectively.

You will see that all supersonic capable aircraft have some sort of device in or near the intakes to slow or change the airflow.

The devices on the F-4's were variable inlet doors.

They would move the supersonic shockwave far enough out front of the intakes.

They would also slow the air to subsonic speed.

If you ever heard that high pitched whistling noise on an F-4 or any supersonic capable aircraft in the landing pattern,it's the variable inlet doors moving to disrupt the airflow for the engines to use the air more effectively.(It's the air molecules screaming in pain)

At least that's what they taught me in F-4 NATOPS training.

[Gr.Viper 131]

That's how it works on MiG-25. Airflow is slowing down in stages.

 

BUT, the shield there also separates intake air from boundary layer.

[DWCAce 19]

The F-14 uses a similar method for the same reasons.

 

Graphic from Torsten Anft's MATS.

[JediMaster 451]

That's the unique part of a scramjet...it can use supersonic air.

[DWCAce 19]

Doesn't a scramjet require supersonic air?

[JediMaster 451]

Yes, otherwise it's just a ramjet.

[DWCAce 19]

Ramjet, Scramjet, Ram Jam, it's all good to me!