Never heard of Photobucket or numerous others eh? :rolleyes:

Missed the couldn’t be bothered bit?

“Specifically, experts speculate that the F-22 engine exhaust radar blocker will be applied to the JSF as well. Engineers have toiled to develop a device to block the radar return of the exhaust cavity and simultaneously survive the extreme temperatures (Fulghum “Stealth is Still…” 46). Researchers from Lockheed claim to have developed a method of blocking the radar return of the F-22’s nozzles without compromising the fighter’s IR signature. . .”

(I suspect “Amiga500” will zoom right to the EJ200’s nozzle, be blinded by the struts visible there, completely miss everything else, and come back with something along the lines of “see, they’re spray bars just like the Typhoon!” )

I’m sure you’ll point to the bit where Amiga500 said exhaust radar blockers were impossible….?

I’m also sure you’ll point to the bit that specifically states (from your evidence…?) that those exhaust blockers exist downstream the AB injectors….

That would be UPSTREAM of the radar blocker in it’s exhaust.

Yes that would be.

Unless you are now suggesting that a radar blocker would also block IR signature? :confused: (read the context of what you’ve quoted is :))

Why else would I talk about the combustor (i.e. IR) and not the turbine (i.e. radar)…?

The same place the afterburner spray bars are incidentally, UPSTREAM of the radar blockers.

Nope.

The radar blocker might be incorporated between final turbine stage and the spray bars, or as djcross as indicated as an integral part of the spray bars… but not downstream the spray bars… not at 2000+ degK.

Your original post is this:

[COLOR=”DarkRed”]And no, you can’t look up the exhaust and see the fuel injectors. If you look at the right pictures (and I have) and read the right sources (I have) you’d know there are radar blockers there which makes it so you can’t see them. You can see the radar blockers in the exhaust and you can see (from the engine exterior) that the fuel injectors for the spray bars are well upstream from the blockers. Right where they should be.

And its rubbish, as proven both by tempterature limits and this:

http://op-for.com/raptor1.jpg

Clearly visible spray bars and the resultant combustion.

http://pds13.egloos.com/pds/200903/02/84/a0114784_49ab76bf4cdb7.jpg

Clearly visible spray bars.

If you still cannot see this as reality, then I cannot really help you any further bar getting someone from LM to take you to see the nozzles and explain them to you… and that is not gonna happen.

The T-50 engines might have a layer of ‘ceramic’ RAM as a way to reduce radar and IR signature

No, no, no, no.

Its subject to the same problems as the F-22.

The heat is in the plume, not surface heating of the nozzle.

The YF-23 sheilded the initial plume from the ground and to a degree from the side due to the presence of its elevons until it had mixed somewhat*… but behind and above, and you’d see it. The YF-22/F-22 & PAK-FA are nothing like that**.

Besides, nozzles operate at 2000+ degC – so something is up with that quoted text. I suspect (but cannot be sure) that they are actually talking about the RAM layers applied to the fan on the Su-35/27/whatever BM to reduce the frontal RCS.

*see below:

**see below:

If you take the trouble to look at the picture, you will notice, without much effort, that the afterburner is used (perhaps it’s during a take-off?).

No… really?

I hadn’t noticed [/sarcasm]

Why don’t you ask your friends at LM with whom “you’ve been talking to”? They should know. After all, they designed the thing.

I am asking you the question because you are adament they did design IR surpressive features in. Obviously you are going to have to provide some information on these (non-existent) features. Otherwise keep quiet.

I don’t have to ask them (again), because they’ve already told me… there is nothing in there to reduce IR. But seeing as you didn’t believe me, and are showing a startling disregard for basic fundamentals of jet propulsion, and of physics in general, your probably going to plough on ahead and insist you are right anyway.

They also designed the F-117, which lacks afterburners anyway, but still has similar arrangements in its nozzles and additionally has a mechanism mixing cold air with the fumes.

Similar arrangement?

That clueless meter just keeps on rising.

Even the cross section of the exhaust helps in the IR because the heat diffuses faster than with a circular exhaust.

The F-22’s chevron nozzles do not penetrate the ambient or exhaust flow, its not their design goal. Thus no added mixing from the chevron shape.

A rectangular nozzle will induce greater mixing of the flow due to screech… which will help attenuate the high temperatures of the jet plume. However, to put some numbers on it, a round jet will have a turbulence peak at around 6-9 nozzle exit diameters behind the exit plane itself. A square nozzle will reduce this to around 4-6… both of those figure ranges are dependant on a few things like aspect ratio or boat-tail angle.

Anyway, back to the point at hand. LM did not design any part of the ducting/nozzle for IR signature reduction. It is an entirely useless gesture to reduce your wake plume average temperature 5 metres behind the aircraft from (approx) 600 degreesK above ambient to 550 degreesK above ambient… (just realised that I’ve posted 600 degK in the earlier post, should be ~900 degK absolute)

And no, you can’t look up the exhaust and see the fuel injectors. If you look at the right pictures (and I have) and read the right sources (I have) you’d know there are radar blockers there which makes it so you can’t see them. You can see the radar blockers in the exhaust and you can see (from the engine exterior) that the fuel injectors for the spray bars are well upstream from the blockers. Right where they should be.

I do not know what fairy tales you’ve been reading, but there are few substances known to man that can withstand 1800+ degrees Kelvin without active cooling. There are none that can take those temperatures, and absorb EM waves.

You can read whatever you want, and you can look at whatever pictures you want. You are living in a dream world and unable to separate objectional reality from desire.

The injectors can quite clearly be seen here:

Maybe the Russians do use some similar to avoid the need of a S-duct?!

I would seriously doubt it.

A blocker is a band aid fix at best.

It kills pressure recovery from inlet to fan face. I think there are figures on line for how much the blocker reduces SH engine/intake duct performance.

No, actually the nozzles themselves are an IR reduction feature. That is why they are part of the airframe and not the engine itself, and additionally that’s why Raptor’s TV is limited to 2D.

No. They aren’t.

100% fact and not up for discussion. There is not one piece of the Raptor’s engine ducting, either up or downstream designed for IR suppression.

The nozzles are designed to reduce radar signature (in all directions bar being directly behind where you can look up into the afterburner fuel injectors).

I know 😉