Most of my experience with Kopp is from rec.aviation.military in the 90s. He was interesting to read and seemed to know his stuff and wasn’t quite the fanatic he seems to be at times today. Him and Kurt Plummer both- people either liked them or they hated them. There wasn’t much in between.

This is a good conversation though. 🙂 I have an F-22 question as soon as I mark the picture. I’ve been looking at the back end of the F-22 (before this) and in some of the larger images I noticed a suspicious feature that shows up particularly well in the picture you posted. Any idea what these are?

Got to agree I’ve enjoyed this thread, I was also a regular on Rec.aviation.military, I think Kurt’s still around on selected boards, but didn’t he just go on and on with slang and TLA’s made confusing and heavy reading.

As for those thingos at the rear they look like they are to do with shock waves, the two middle ones are not being used, they are there just to make the engines swappable between left and right, the outside ones are there to protect the tail from the airflow. thats what it looks like but this is just a guess.

Cheers

It suggests exactly what it says: that they did trade studies. Just like they did on every other part of the aircraft. It doesn’t say in there that they had to accept a lower degree of stealth than required to do the job. In the trade they probably said something like “is what we can achieve for a reasonable cost good enough or do we need to spend more money to make it better?” If an F-15 or F-16 can’t see it from the rear even though they were told where the thing was they obviously got it good enough.

Exactly, they had to trade something… why do you think it was the low observables team that was doing these tests, if the LO wasn’t the problem what was it that the LO team were responsible for??, remember the engine was meeting or exceeding its thrust and manoeuvring specifications!! and money is very tight.

Couple that with the previously mentioned rewriting of the original LO specifications due to the F-22 not meeting its LO specs.
The only reason you’d rewrite LO specifications is so that it will meet the new targets..not because it was exceeding those targets, granted it well may have a ‘good’ rear RCS figure, not what was originally specified, but just good enough..

You have to remember the situation the F-22 has been and still is in, with funding scarce, the buzzards circling, a failure to meet LO targets may have dealt a mortal blow to the F-22’s, so if a design tweaking was needed, LO targets were redefined, various holes, panels and the Nozzles were duly tested and “well I never!! the little beauty’s passed with flying colours, now can we please have more funding for the production units !!!” , you can see how it works

Several key targets for the F-22 have not been met or have been redefined..
First was the 2000′ landing distance was redefined
Then the 50,000lb weight limit was redefined,
then the LO was redefined,
the airlift support hasn’t been met,
nor the time between maintenance actions,
nor the MMH/FH,
and many more I’ve probably forgotten (anyone have a comprehensive list?)

Redefining targets makes sense for the USAF – without it the program would look like it failed to meet the majority of its original key parameters, and that isn’t a good look when the funding buzzards are circling..

so I’m still failing to see how anything other than “all aspect stealth” applies in regards to the F-22.

OK one last time – relaxed LO at the rear is still “all aspect” it just meets a different ‘more relaxed’ level of LO..

I generally like Kopp but when it comes to the F-22 he makes me look downright reasonable. 😉 I’d be more concerned with the F-35’s limited AAM payload in stealth configuration as well as it’s speed and manueverability limitations than a 5 degree cone of visibility to the rear. The thing has software to tell it where to go so it’s not pointing it at transmitting threats anyway.

OOOwww don’t say you like Dr Kopp.. where’s your self respect!!!:), I have argued with Carlo on many many occasions re the F-22, and I think I told him once that I would be scared to leave him alone with an F-22, think of the offspring of that union 😮

IMHO While Carlo’s data is usually accurate the conclusions he reaches range from the ‘surprising’ to ‘WTF’???. with that said, it wasn’t all bad – I think his best written piece was on the Alarm missile.

hmm time to go.. There’s a huge steak with my name on it about 5 meters away and I’m about to dribble on the keyboard:D

Cheers

I’ll try to track it down (won’t be ’til tomorrow though- family party)

Now worries YourFather came up with the quote…

As for the PDF there’s nothing in there that supports your claims. The only thing even mentioned about the rear of the aircraft was that the engines were a tough problem. There was nothing in there that even suggested that they had to settle for less though.

Hmm not even the quote :-

An extensive test program was conducted on a full-scale twin nozzle model to make design trades and to generate a final design

What does that suggest?? bearing mind its the manager of the F-22 low observables IPT team who wrote it.

Depending on the design a gap doesn’t automatically translate to increased RCS.

lol Well the F-22 RCS guy disagrees, he said in the same document :-

Further examination shows that all of the surfaces
between the edges are smoothly blended, allowing
electrical surface currents to flow over the surfaces
without interruption. Any break in the surface causes
energy to be reflected back to the radar, raising the
aircraft’s signature

What is interesting is the 5% quote for the JSF, this must be the achilles heel that Dr Carlo Kopp talks about when he says the JSF is not all aspect..
now it seems a pretty thin argument.:D

Cheers