Forum: F-22A Raptor

Last edited by zeroyon04 on Jul 11, 2007 - 02:41 PM; edited 1 time in total

I just noticed something... the Su-37 didn't have 3D TVC, correct? The engine it used (the AL-31FU) only moves in the vertical plane (just like the F-22). And the Su-30MKI doesn't really either. The Su-30MKI (and Su-30MK prototype #6) uses the AL-31FP, which uses two 2D nozzles mounted perpendicular to each other, to give a pseudo-3D effect. As in, (looking from the back) the right nozzle only moves from top-right to bottom-left, and the left nozzle only moves from top-left to bottom right.
For example, if the left nozzle moved to top-left, and the right nozzle moved to bottom-left, it would give it a yaw motion to the left.

It wasn't until the MiG-29 OVT came along, that russia had a nozzle that matched what was used on the F-16 MATV and F-15 ACTIVE.

How did it ever perpetuate everywhere that the Su-37 has 3D thrust vectoring?

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Last edited by zeroyon04 on Jul 11, 2007 - 01:49 PM; edited 1 time in total

sorry, double posted...

zeroyon04 wrote:

I just noticed something... the Su-37 didn't have 3D TVC, correct? The engine it used (the AL-31FU) only moves in the vertical plane (just like the F-22).

Well thats news to me... do you have a source to go with that info zeroyon04?

Another thing to consider is that the Raptor's engine and airframe was built to accomodate TV while the Su's was simply an afterthought. Also, the F-22' s TV functions with a +- 20 degree envelope while the Su's only operate at 15 degrees. Any statement that involves Russia being superior to the US with TV tech is bold to say the least.

Last edited by zeroyon04 on Jul 11, 2007 - 05:30 PM; edited 3 times in total

The info is almost anywhere that has info on the Su-37, look here for example:

from here: http://propro.ru/flankers/eng/Su-37.htm

"The axis-symmetric swivelling nozzle is secured to the annular swivel and can be moved in the pitch plane with the aid of two pairs of hydraulic jacks."

and from here http://www.fas.org/man/dod-101/sys/ac/row/su-37.htm

"The nozzle only moves in the pitch axis"

and here http://www.sci.fi/~fta/Su-27.htm

"Saturn/Lyulka General Designer Victor Chepkin confirmed to Piotr Butowski (Jane's) that work on a three-dimensional (axisymmetrical) TVC nozzle was underway but that it was not planned for the Su-37 in the immediate future."

and here http://www.milavia.net/aircraft/su-37/su-37.htm

"the Su-37 engine nozzles swivelled only vertically,"

The AL-31FP it talks about on that page above is the one I described on the SU-30MKI BTW.

you can even see that this is the case in this video:
http://www.youtube.com/watch?v=GaUxabw5 ... ed&search=

Ask yourself this, have you actually ever seen a video or even a picture showing the Su-37 with thrust vectoring in the horizontal axis?

Thanks Zeroyon! that is very interesting... yet another example of the Russian Aerospace community trying to exaggerate the features of a sub par aircraft.

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Folks during the F-22 'helicopter spin', it IS the rudders he's using to yaw the jet.

Active member Joined: Nov 22, 2004 Posts: 134

Night wrote:

I believe the F-22 has better flight control computers then the sukhois, and doesn't need 3d TVS to accomplish the same feets.

It's not just the computers and the control laws--regarding the topic at hand, the F-22 has better aerodynamics than the Flanker.

Scorpion1alpha wrote:

In reality, the Raptor's maneuverability is very much UNDERSTATED, whereas the MIGs and SUs are doing everything they can to sell their aircraft based on what it can do in a airshow configured, heavily modified airframe with a specially trained company pilot flying them.

They've been doing this for much longer, too, and take it as far as they dare, crashing a number of aircraft in the process. Obviously, the USAF cannot afford to do this with the F-22, so they're always going to be more conservative. That said, if these are conservative demonstrations based on standard combat-capable airframes, then WOW! Shocked

Note also that the F-22 is pretty much always in control, whereas the other fighters in question often throw themselves around wildly until they reach some predetermined recovery point--the result looks spectacular, but is not as impressive from a technical point of view, nor from a practical one.

Afterburned wrote:

I would like to know how the raptor can execute what looks like a controlled nearly flat spin with 2-d VC... something to do with the huge control surfaces or perhaps sending more thrust through one pipe than the other???

It's a combination of great aerodynamic performance and flight control design.

zeroyon04 wrote:

I just noticed something... the Su-37 didn't have 3D TVC, correct? The engine it used (the AL-31FU) only moves in the vertical plane (just like the F-22).

That's right, and the canards are there for greater control and stability at high alpha, among other things. By the way, the baseline Su-27 actually does not have great aerodynamics at high alpha--it's better than most fighters in this respect, but not as stable and controllable as the F/A-18, for example, much less the F-22. However, it does have a unique recovery mode around 90 degrees alpha, which is how it performs the Cobra. Additionally, its engines and their integration are quite robust, of course.

zeroyon04 wrote:

And the Su-30MKI doesn't really either. The Su-30MKI (and Su-30MK prototype #6) uses the AL-31FP, which uses two 2D nozzles mounted perpendicular to each other, to give a pseudo-3D effect. As in, (looking from the back) the right nozzle only moves from top-right to bottom-left, and the left nozzle only moves from top-left to bottom right.

That's right, although the angle between the vectoring axes may be less than 90 degrees, otherwise there might be too much of a compromise to the pitch vectoring force, as well as an excessive corkscrew-type force possibly.

zeroyon04 wrote:

For example, if the left nozzle moved to top-left, and the right nozzle moved to bottom-left, it would give it a yaw motion to the left.

That in addition to a rolling moment, although it may not be that severe and could be compensated for most of the time. It doesn't matter much if the main point is to do cool airshows. Smile

zeroyon04 wrote:

It wasn't until the MiG-29 OVT came along, that russia had a nozzle that matched what was used on the F-16 MATV and F-15 ACTIVE.

Yes, this nozzle design provides a lot of thrust vectoring force in both pitch and yaw, allowing the MiG-29OVT to perform some quite spectacular maneuvers. That said, the only one that really impresses me is the first one, performed shortly after takeoff; the rest of the current demonstration seems kind of lackluster to me, actually. Maybe I'm biased, but the F-22's demonstration is more impressive overall, in my opinion, despite being done under more limited conditions.

zeroyon04 wrote:

How did it ever perpetuate everywhere that the Su-37 has 3D thrust vectoring?

It's mostly the wishful thinking of fanboys, I suppose (not that it's significant in the real world anyway). It's not so different from people saying that the top speed of the F-15 is Mach 2.5 as if a real F-15 would ever reach that speed (or even half that most of the time) in combat, for example. With the Su-37's spectacular displays, this sort of thing is greatly magnified, giving it virtually every capability that anyone has ever thought of, including stealth. Yep, there are people who say that the Su-37 (or the Su-30MKI these days) has a RAM coating or a plasma generator that makes it just as stealthy as the F-22. Uh-huh.... Rolling Eyes

It's also quite likely that many people automatically associate the round (axisymmetric) shape of the nozzle with being able to vector in a circular pattern, since they were accustomed to seeing paddles or rectangular 2D nozzles. Don't ask me why--it's just how the typical person's mind works.

Afterburned wrote:

Also, the F-22' s TV functions with a +- 20 degree envelope while the Su's only operate at 15 degrees. Any statement that involves Russia being superior to the US with TV tech is bold to say the least.

That's certainly true for thrust vectoring, but somewhat understandable because Russian manufacturers are so much more aggressive at marketing this technology, while the USAF's general indifference toward it (for good reasons) discourages US manufacturers from doing the same. Let people believe whatever they want, and during actual combat, let the chips--and enemy aircraft Wink

--fall where they may.

Forum: F-22A Raptor

Pitch/Yaw TV vs Pitch TV on the F-22