the f-22s main engineering flaw - Square exhaust

[popcorn]

i totally understand, my subject of expertise is the F-16, most of which i learned from my dads war story's

F-16 is a good base to start building upon, specially for things F-35. If you haven't stumbled across it yet, Second Lineof Defense is a good resource.

[JetTest]

Troll or moron, which is it?

just someone here to learn

If you had started off with that short simple intro instead of the way you did, making rather ridiculous statements of opinion about things with nothing to back them up, and then trying to continue to argue those points with people some of whom have either worked on the development, manufacture and flight test of these aircraft, or have flown them for sometimes for thousands of hours, you would have received a much different and more cordial reception. Welcome! To your point, there is a great deal of knowledge here and people are generous and willing to share what they can when asked. I think we all learn some things from time to time.

[count_to_10]

just someone here to learn

A bit of advice: post questions, not statements. It also helps a lot if you can post a link to an article that illustrates where you are getting the question from.

[cooldude2819]

just someone here to learn

A bit of advice: post questions, not statements. It also helps a lot if you can post a link to an article that illustrates where you are getting the question from.

sometimes controversy can be the best way to glean information

[popcorn]

just someone here to learn

A bit of advice: post questions, not statements. It also helps a lot if you can post a link to an article that illustrates where you are getting the question from.

sometimes controversy can be the best way to glean information

Clearly not in your instance. Next time just ask and spare the drama.

[mixelflick]

5 star thread, one of the best on the interwebz...

Troll or just mis-informed? Don't think we'll ever know. One thing I am curious about is just how much technology advanced re round exhausts from the F-22 days. Sorry if I missed it in this thread. My first thought was to retro fit stealthier nozzels into F-15's/16's but obviously, F-15 still has radar signature of a barn door. The F-35 is growing on me, albeit nobody's knocking the F-22 off the top spot. Not one but TWO airshows up my way (New England) during May, featuring the Blue Angels/F-22 demo team

Happy, Happy man...

[mrigdon]

One thing I am curious about is just how much technology advanced re round exhausts from the F-22 days. Sorry if I missed it in this thread. My first thought was to retro fit stealthier nozzels into F-15's/16's but obviously, F-15 still has radar signature of a barn door.

You mean like this? http://www.f-16.net/f-16_versions_article20.html

I'd guess that the radar and infrared returns from these aircraft are so large that fitting a new nozzle wouldn't make enough difference to help. The Super Hornet is basically a brand new plane, for instance. It wasn't just about attaching stealth bits to the older Hornet.

[mixelflick]

You mean like this? http://www.f-16.net/f-16_versions_article20.html

I'd guess that the radar and infrared returns from these aircraft are so large that fitting a new nozzle wouldn't make enough difference to help. The Super Hornet is basically a brand new plane, for instance. It wasn't just about attaching stealth bits to the older Hornet.[/quote]

Yes, thanks so much. I read this is A LOAN (Low-Observable Asymmetric Nozzle). Does that mean the nozzle can swivel to some extent (i.e. provide some degree of thrust vectoring)? And if that answer is yes, does the F-25 currently incorporate/have that ability?

[Scorpion1alpha]

does the F-25 currently incorporate/have that ability?

Wait, we have an "F-25"!?!?

Ooohhh...can I see it?

[sprstdlyscottsmn]

No, the LOAN is just the answer to how to get a round LO nozzle. It has no TVC characteristics.

[mikejamesmedia]

I don't personally have any "insider" information, but last night, I was watching this nicely-subtitled video regarding the Russian T-50. Naturally, they discussed the F-22, by way of comparison.

It was mentioned that one reason to go with the flat interior shape of the thrust-vectoring paddles is that a flat surface is better at absorbing heat... thus improving the thermal aspect of stealth.

When you think back on what has been said by the manufacturers about the exhaust design of both the F-117 and the B2, this makes sense to me.

[zero-one]

Lets cut the new guy some slack and try to answer his question.

1st you started by asking "who was the dufus engineer who installed square nozzles on the F-119 engine?"

A little history the Pratt and Whitney F119 started life as the PW5000 engine. And the requirements were pretty steep, especially when you consider that most of the development was done during the 80s.

Some of the requirements were:
-must have exceptional Thrust-weight ratio, possibly the highest in the World
-must have low observability in both the Radar and infrared spectrum
-must be equiped with thrust vectoring for increased slow speed maneuverability

Now do we honesty think after 5 minutes of brain storming over lunch at McDonalds they just got up and said, "hey lets make it a square nozzle"

It took years of intensive test and development before coming up with the best possible design.

Square nozzles does pose additional problems, such as reduced thrust levels and increased ware and tare.

However again, years and years of intensive research was done to maximize the thrust output of the square nozzle and minimize the ware and tare,

The Russians experimented on square nozzles and found that it reduces thrust by 14-17%.
Now the Russian square nozzle design was significantly different from the f-22s nozzle design, which means that the thrust reduction is not the same as well

I would say they acheived a thrust reduction that is far lower than the Russian design which was very short lived.

How far does it reduce thrust, we don't know, but what we do know is that even with square nozzles,
Static uninstalled thrust rates from the F-119 engine still punches out at 35,000 lbs, which is the second highest thrust rate for a fighter engine (just behind the F135 which blast 43,000 lbs, if you think about it, the F135 is basically a modified F119, so in essence, its safe to say that a round nozzled F119 may have a thrust rate of around 40,000 lbs.)

The most powerful Russian fighter engines with round nozzles can only produce around 31,900 lbs. (AL-41)

Increased ware and tare? Sure, but again nearly a decade of intensive research, development and testing allowed them to produce a square nozzle that would minimize the extra ware and tare,

The result? F-22s are some of the most combat ready fighters in the World and have a very high mission readiness rate.

[KamenRiderBlade]

does the F-25 currently incorporate/have that ability?

Wait, we have an "F-25"!?!? :-o

Ooohhh...can I see it? :D

<joke post>
http://www.macross2.net/m3/macrossf/vf-25f.htm
</joke post>

[popcorn]

Russian efforts at LO nozzle design. Remains to be seen if this will ever amount to anything.
http://defence.pk/threads/low-observabl ... ft.328253/

[mixelflick]

does the F-25 currently incorporate/have that ability?

Wait, we have an "F-25"!?!?

Ooohhh...can I see it?

Yes, afraid you can't see it though. Only me and a select few others, like my 9 year old son Nicholas Maximus. Mach 8 supercruiser, zero radar/infrared due to plasma stealth and an engine with no moving parts. Engine nozzels can morph from circular to flat as the situation calls for it..