F-15 "Variable" Inlets

[GGTharos]

If the compressor stalls, and the engine is still burning fuel you get an engine fire.

[Avilator]

If the compressor stalls, and the engine is still burning fuel you get an engine fire.

 

I was aware of that, but would the supersonic air physically break blades off?

[mvsgas]

It could It depends in many things. Severity of stall, engine design, etc.

[Avilator]

It could It depends in many things. Severity of stall, engine design, etc.

 

Gotcha

[mvsgas]

By the way I was saying that back ward Stagnation is a non recoverable stall. At any rate the variable intake is suppose to help with this at high speed but does not mean it will prevent it.

[mikoyan]

They probably also work as the slats on a wing, creating more lift and shaping the airflow over the fuselage; one of the reasons the eagle is such a great dogfighter; to me it is very impressive that after so many years this machine still one of the best dogfighters in the world; true testament of the quality of the work dome by McDonnell Douglas and NASA, if you look in youtube there are videos of small scale model testing flat spins on a wind tunnel and also the drop test from a huey helicopter.

[mvsgas]

The F-22 has variable inlets ... they're not not 'traditionally variable', ie. there has been talk of using means other than physically moving ramps to shape the airflow.

 

So GG, I know you posted that you do not know how it would work, but it a very unique idea. Do you have a link to this talks, I would love to read some of this things.

[Squid_DK]

JAS-39 and J-35 (F-35 & RF-35 in RFAD service) don't have variable inlets.

 

Staffan

[mvsgas]

I was looking around for the whole F-22 intake moving and I found this. I think is funny, the guys is obviously trolling.

http://www.f-16.net/f-16_forum_viewtopic-t-12789-start-0.html

[vanir]

I read a description of how the F-16 inlet shape allows an effect similar to movable ramps, something about the turbulence created around the upper lip because of its shape making movable ramps/inlet superfluous for Mach 2 flight.

Presumably the F-22 is operating on the same system with the design of its inlets, where the F-35 inlet design is optimised for low alt and speeds of up to 1.8 Mach only, mostly a high transonic efficiency.

 

I find it highly unlikely a complicated system of mechanically compressed air injection or sonic traps are used in the F-22, although these conceptualisations might very loosely describe this effect of high speed turbulence in the F-16 style inlet functionality at speeds of around Mach 2.

[mytai01]

That is most likely primarily about hiding the turbine blades from enemy radars, since exposed turbines make up a surprisingly large fraction of the radar return. Ensuring that an enemy radar cannot get a direct echo from a turbine is an instant and massive radar cross section reduction.

 

You'll see the same feature with the russian PAK-FA.

All supersonic jets have to slow the airflow to subsonic before it hits the fan front. None can accept supersonic air directly. Only a ram jet can accept direct supersonic air. Slowing the air would be the primary reason for the design, radar cross section would be a secondary benefit and not very effective.

[MaverickF22]

That is most likely primarily about hiding the turbine blades from enemy radars...

 

You might want to say compressor blades..., the turbine is well hidden between the exhaust nozzle and combustion chamber, radars mostly can't see the turbine, but rather the first compressor stage!

 

 

Cheers!:thumbup:

[popcorn]

Yes, notice than most aircraft that can achieve high speed flight (Mach 1.5+) have variable intakes. Come to think of it, I only know two modern aircraft that can reach those speed and do not have a variable intake, the F-18 and the F/A-18.

F-16 could reach Mach 2.0 with standard pitot intake but I believe it has one of those new diverterless supersonic intakes on later models.

[GGTharos]

Talk about necroposting ...