Forum: F-35 Lightning II

http://www.sukhoi.ru/forum/showthread.p ... mp;page=81

T-50 is in trouble at ground test.
it seems that this problem is more serious than F-35B.

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Mate i'm dying to read that but its all in Russian, can you explain roughly whats going on?

Google Translate can sometimes do a better job compared to Babel Fish but I do not know Russian to compare. This looks like 'Double Dutch' in English but what do I know:

http://translate.google.com/translate?j ... mp;act=url

Heh those translations are pretty funny but it seems its something about 'vortices shaking up the keels' or something.
Think i'll await a proper translation...

Buffeting, simple buffeting. F-22 and Su-27 too experienced problems with buffeting during the tests.

I take it you meant the YF-22. Do you have any idea what they plan to do about it?

Edit: according to the link below the YF-22 buffeting was fixed by a software tweak.

"I was also pleased with how smoothly the airplane went through all the ground checks and how smoothly the airplane flew. As an example, the flap schedules on the original F-22 shook the Raptor at speeds above 200 knots. This objectionable buffet was addressed right away through a software change. Paul Metz [first pilot to fly the F-22] and I are the only two pilots who ever experienced that buffeting. I thought that I might experience some sort of buffeting with the first F-35, but I didn't."

http://www.wingsoverkansas.com/features ... asp?id=797

Last edited by quadrofx on Jan 31, 2011 - 11:46 AM; edited 1 time in total

qwe2008
You wrote that there are problems, but could not describe the nature of these problems. In Russian there is a saying: Heard a bell, but doesn't know where it is.
That's funny.
Sorry for my English.

In Su-27 this problem was solved by moving the vertical tail to another location.

To be fair to qwe he did not say he didn't know what the problem was, perhaps he did know but couldn't be bothered to tell us or ran short of time or perhaps he didn't know. We will never know for sure.
Don't read to much into a short forum post.

quadrofx wrote:

In Su-27 this problem was solved by moving the vertical tail to another location.

That's interesting but sounds a bit much to be a quick fix. Perhaps software is the key to solving it as it was with the YF-22 (though that did seem to be a far more minor buffet problem as i understand from elsewhere this problem on the PAK-FA is affecting the structure.)

Quote:

is affecting the structure

You mean the rumors of flutter, which went recently?

No I heard it was in relation to this problem.

Of course without official word (which I doubt we'd get from the Russians what with openness and transparency not being their thing) we are all very much in the dark.

shep1978 wrote:

I take it you meant the YF-22.

He does mean F-22 (well, F/A-22 at the time).
Bird had this problem at early stages of EMD tests.
ttp://ntrs.nasa.gov/archive/nasa/casi.n ... 060467.pdf

"Extraordinarily large buffeting loads were also seen on the F-22 during the flight clearance phase of its program."

X-35 didn't miss buffeting as well
"In 2001, during the contract competition phase of the Joint Strike Fighter (JSF) program, Lockheed-Martin (LM) attempted one high angle-of-attack maneuver of its X-35 prototype. Upon reaching 18 degrees angle of attack, a Mach number of 0.75, and a dynamic pressure of 325 psf, the “knock-off” g-load limits on the tails were reached due to buffet, thus ending the maneuver."

Yes you're quite correct Flateric, if i'd have read what I posted in this very thread a bit better than I would have seen that mistake myself.

X-35 isn't F-35 (as i'm sure you are well aware) though it is still interesting to learn that had a buffet issue.

This photo/blog post needs a LAFF track:

http://www.peopleforum.cn/viewthread.ph ... a=page%3D1

Forum: F-35 Lightning II

T-50 is in trouble, good news for F-35