Inviting pilot of Eagle and Fighting Falcon

[rousseau]

Hello:
I am curious man who always bring a lot of strange questions to you. I hope that my question won't make you angry, if you don't like me, beat me:}
But for took such risk, please allowed me to post question here.

Did you find some nozzle of Eagle was covered by hood or say long fish scale, but some wasn't.
http://www.haynesintl.com/nozzle.jpg
http://upload.wikimedia.org/wikipedia/commons/b/b2/F-15_nozzle.jpg
But almost all of nozzle on F-16 was covered by hood
http://attach.high-g.net/attachments/pw_nozzle.jpg
So, Would you please tell me why? And what reasone these hood covered this nozzle for?

[c-bert]

The exhaust nozzle diameter changes to maintain the optimum level of thrust. It's all to do with supersonic flow through a nozzle. Unfortunately I've forgotten 95% of the stuff I learnt at uni so that about all I can tell you. :ok:

[Someone Different]

I think (!) I know what you are asking. IIRC (and I remember noticing and asking about the difference some years ago) and IIWIC the airflow at the back of the F16 was still in some semblance of order, so it was worth putting some aerodynamic 'smoothing' around the petals, the airfow at the back of the 15A/B was already messed up enough not to warrant the extra weight/maint of the shroud. The lineys seemed to think it was much more to do with maint side of things.

I am sure there is an Engineologist out there who knows..........

SD

[bArt2]

@ rousseau and Someone Different.

Did you guys send your message through an Enigma machine? :}

I've read your messages a few times but I have no clue what you're actually asking or saying.

Sorry.

Greetings, Bart

[Archimedes]

Do you mean "why were the 'turkey feathers' removed from the PW F-100s on F-15s , but left in place on similar engines in the F-16?"

If so, something (IIRC) to do with the F-15 having major maintenance problems with them. From memory (context - conversation, F-15C driver, beer) there were dynamic load and vibration issues thanks to the two engines being close together, and some of the nozzle components started to fail and fall off in flight. As the F-16 had only one engine, it didn't have the same problem.

Or something like that.

Of course, I may have just given the wrong answer to the wrong question.

[rousseau]

Yes yes, the "feathers", sorry about I didn't know which word should be used to describe it before.
The "feather" also left on some F-15's nozzle.
My inquiry mes cause your angry, but I have to ask again, since smooth air flow was a situation needed, these feathers maybe better for that, why removed from later version of Eagle?

BTW what does that IIRC mean? Could you please give me a complete spell?

[Archimedes]

Sorry - IIRC - If I Remember Correctly/ If I Recall Correctly

I'n not sure why some of the F100 powered F-15s still have the feathers, but I gather that although removing them, increased drag, it did not do so to the extent that the modification caused problems. It also saved quite a lot of weight, I believe.

[MrBernoulli]

bArt2,

Give the guy a break! English is obviously not his 1st language but he is trying.

[DucatiST4]

I believe that the F15's come with a kind of fairing/bodywork around the tail pipe of the engines so you can't see all the moving bits. The engineers found access to the engines difficult so removed the bodywork and left it off as they found that it didn't effect the way the aircraft flew.

[Dan D'air]

Give the guy a break! English is obviously not his 1st language but he is trying.

He certainly is.

[spekesoftly]

rousseau,

You must forgive the last comment, he's only just come out of hospital.:rolleyes: