F-22 vs PKA-FA thrust vectoring

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gta4

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Unread post25 Jan 2018, 12:56

First thing first, PKA-FA DOES NOT HAVE 3D TVC! It is still useing 2D TVC, as revealed in Russian's bureau of intellectual property:
T-50 2d tvc.jpg


Secondly, F-22 has 20 deg of deflection, while Russian has only 15 deg of deflection. This makes F-22 much more agile in the pitch axis, at least judging from airshow moves:
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hythelday

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Unread post25 Jan 2018, 13:12

gta4 wrote:at least judging from airshow moves


I sorry but that is stupid. Airshow videos are only good for seeing what a plane can do, and are worthless as comparison between two jets, because there is no reference for speed, turn rate, altitude and whether a maneuver was best possible or not.

In addition: what is "3D" TVC anyway? Is it when nozzles become longer? F-22 can only control pitch with TVC. Flankers and PAK FA can use TVC to influence yaw too, even if the picture you provided is, in fact correct and not a simplification/misunderstanding.

Your post with numbers from flight manuals are much better that these "airshow video comparisons".
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gta4

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Unread post25 Jan 2018, 13:22

You think T-50's TVC can affect YAW because it is a 2D TVC that moves in a "V" pattern, right?

That is not true. If it wants to create YAW moment, one nozzle mush pitch upward, while another nozzle mush pitch downward. As a result, while it generates the YAW moment you need, it also generates the ROLL moment that you don't want. This is called "parasitic moment"

So, the plane cannot yaw with TVC, because it always has the tendency to ROLL OVER instead of proper yawing.

Oh, do you mean PKA-FA "yawed" during airshows? That was a falling leaf departure that every plane (even without TVC) can do. F-22 can do it much faster:
F-22 heli turn.gif
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hythelday

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Unread post25 Jan 2018, 13:30

You are entering wewuz territory here.

As I said: airshow videos and footage from flight testing is not a "proof" of anything because 1) there are no numbers involved 2) there isn't a reference point.

F-22 can only pitch with TVC. Russian TVC can pitch and also influence yaw rate. Whichever system is "better" or makes plane more agile is a whole different story.
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gta4

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Unread post25 Jan 2018, 13:33

Russian TVC can pitch and also influence yaw rate
-----------------
Prove it.

I have proven that it can not yaw because it has the tendency to ROLL OVER.

And, please prove that "15 deg deflection is better than 20 deg deflection"
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Unread post25 Jan 2018, 14:11

gta4 wrote:Russian TVC can pitch and also influence yaw rate
-----------------
Prove it.

I have proven that it can not yaw because it has the tendency to ROLL OVER.

And, please prove that "15 deg deflection is better than 20 deg deflection"


You seem to imagine arguments just so you can post more gifs from airshows as "proofs", because you want me to prove things I never stood by.

To recap, me statements, nothing more, nothing less:
1) Footage from airshows and flight testing is not a proof of anything since there is no hard data on the maneuvers performed, and as such cannot be used in plane comparisons.
2) F-22 can only control pitch because F119 nozzle only moves up or down. AL-31 can also move nozzle laterally, whether or not this also causes roll is irrelevant because F119 does not have this feature at all (unlike STOL/MTD P&W F100, HARV GE F404, VISTA GE F110 which I know about, just in case). HOWEVER never did I claim that one system is superior to another. MOREOVER system performance is driven in large by design specifications - e.g. YF-23 was as maneuverable as YF-22 without TVC at all - which is why I do not automatically declare one system "better" for the lack/presence of certain features.

You should stick to the numbers and flight manuals, as you once did. Those posts were much better.
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gta4

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Unread post25 Jan 2018, 14:27

AL-31 can also move nozzle laterally
------------------
Prove it.

Su-37, Su-30MKI all have 2D TVC which only moves up and down (in a V pattern). Not laterally.
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Unread post25 Jan 2018, 15:00

YF-23 MANEUVERS AS GOOD AS YF-22?

This is what I have read:

"YF-22 demonstrated 60 deg controllable AOA. YF-23 claimed to have very high controllable AOA but only demonstrated 22 deg. USAF emphasized so much on maneuverability so it chose YF-22."
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gta4

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Unread post25 Jan 2018, 15:04

I think hythelday can't understand the difference between "deflect laterally" and "deflect vertically in a V pattern".

The former generates yaw moment without generating unwanted roll moment. The latter must generate parasite roll moment.

We can't talk with illiteracy. :bang: :bang: :bang: :bang:
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Unread post25 Jan 2018, 15:40

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Unread post25 Jan 2018, 15:58

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Unread post25 Jan 2018, 17:32

"Those who know don’t talk. Those who talk don’t know"
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hythelday

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Unread post25 Jan 2018, 18:08

gta, let me get this straight, you define 3D vectoring as "ability of nozzle to deflect in any direction of 360 deg circle freely just because it is cool" as opposed to "ability to deflect nozzle in a way that assists aircraft maneuver in pitch, roll and yaw"? Because according to your definition there are no operational aircraft with "3D" thrust vectoring, and Raptor is a "1D" TVC aircaft.

I may be illiterate, but I do know how simple vector math works. By deflecting left nozzle UP and LEFT, and right one DOWN and LEFT pilot assists plane in yawing to the left (as seen in Xanders picture up&right corner). Alternatively, if left nozzle is deflected DOWN and RIGHT, while right one is deflected UP & RIGHT the plane yaws to the right (as seen in Xanders picture down&left corner). Pitching momentum is created by deflecting both nozzles UP (but in different directions), while I guess roll could be assisted by deflecting one nozzle more than the over.

I'll let the people of the forum be the judges. If there's really something I understand wrong about Russian thrust vectoring I'll accept it. I'll put it my signature too.
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Unread post25 Jan 2018, 18:34

with the V shaped TVC it can produce Yaw, and yes there will be an accompanying roll moment. The roll is likely desired and if not then a proper FCS can counter the roll moment with inside (direction the nose is yawing) aileron dropping to hold the wing up which in addition also increases the asymmetrical drag pulling the nose in the desired direction for pure yaw.

TVC does not operate in a vacuum, as the Su-35S clip shows.
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Unread post25 Jan 2018, 20:56

Agreed, such video comparisons are worthless. Airshows are airshows and combat is combat, little relation between the two.
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