Su-57 Stealth Fighter: News #8

mnztr wrote:Any truth to them developing flat nozzles for the SU-57 or is it just Western (you must be copying us) BS?

USSR, 1983.

USSR, 1983. wrote:

I believe it was tested in a lab much earlier as well..

I also personally think the flat nozzle is a waste of time and nerfs performance on a fighter aircraft. A fixed stealthy nozzle like the one they want to put in the S-70 Okhotnik then sure. But I am not the one who decides if these things should be funded or not.

GarryB wrote:
Your previous post you said the Su-35 used 2D angled TV with the engines canted to give a sudo 3D effect.
Now you say they are 3D TVC

Sorry but in all my posts about the Su-35's TV's I have clearly stated that they are 3D?
However it is quite clear from your posts that you believe they are 2D.

GarryB wrote:The engines on the Su-35 flanker are 2D as well but are round.

You also claim that they are 2.5D but in all of the literature that I've seen about TVC's they only mention 2D and 3D vectoring, but feel free to enlighten us with some credible evidence on 2.5D TVC's.

GarryB wrote:which is why it sometimes gets called 2.5D

Here is an example: It's from ITP's study on THRUST VECTORING NOZZLE FOR MILITARY AIRCRAFT ENGINES:

From the point of view of the direction of vectoring, TVNs can be classified:

• Single-Axis TVNs: (also called 2-D or Pitch-only)
The deflection of the gas flow is achieved in vertical direction only. They replace and/or complement horizontal control surfaces. This type is suitable for
all types of variable geometry military aircraft nozzles, for applications without Post-Stall.

• Multi-Axis TVNs: (also called 3-D or Pitch and Yaw)
The deflection of the gas flow is achieved in any direction. They replace and/or complement horizontal and vertical control surfaces. This type is specially
suitable for round nozzles, for applications with Post-Stall.

As you can see from the above 2D and 3D all depends on the gas flow direction that the nozzles can achieve.

Here again is what I wrote about the Su-35's 3D TVC.

Mir wrote:the canting allows roll and yaw moments by vectoring each nozzle differentially, thus enabling the aircraft to produce thrust vectoring moments about all three aircraft axes, pitch, yaw and roll.

It's not "sudo" as you mentioned - it's a very basic principal and real science. Actually it is quite brilliant.

Just a side note from Yefim Gordon's 2001 publication: Flankers - The New Generation:

The Sukhoi OKB began initial TVC studies as early as 1983. By then the Western press described 2D vectoring nozzles as the best option. However Sukhoi's Michail Simanov insisted on 3D axis-symetrical vectoring nozzles. It should be noted that Sukhoi worked on 2D nozzles as well. For example the boxy flat nozzle that was tested on the T10-24 was 2D.

In fact the US were the first to develop a 3D axis-symmetric nozzle but it was never deployed - rather opting for a 2D nozzle for their 5th gen  F-22.

Also - From wikipedia.ru:

Klimov, [as] one of the leading Russian turbofan manufacturers, which also produces the world's only serial nozzle with an all—angle thrust vector deviation for installation on RD-33 and AL-31F engines.

List of aircraft fitted with a 3D axis-symetrical vectoring nozzle;

Rockwell-MBB X-31 (Experimental aircraft of the X-planes series)
MiG-29OVT
MiG-35 (optional)
Su-27SM2 (AL-31F-M1 engine, Product 117S)
Su-30 (AL-31FP engine)
Su-35S
Su-37
Su-57
F-15S (experimental)

A flat boxy 2D nozzle was tested in a fight on a flying laboratory that used only one nozzle like that, while the other was standard for Su-27.

ALAMO wrote:A flat boxy 2D nozzle was tested in a fight on a flying laboratory that used only one nozzle like that, while the other was standard for Su-27.

Yes I mentioned it in my post directly above - post "906"

Mir wrote:It should be noted that Sukhoi worked on 2D nozzles as well. For example the boxy flat nozzle that was tested on the T10-24 was 2D.

GarryB wrote:I have seen vectored thrust engines on the Su-35 but not on the in service MiG-35s.

These are optional only as mentioned above, although I believe you thought they come as standard?

https://www.russiadefence.net/t8995p25-competing-aircraft-designs-of-the-90-s-and-beyond

GarryB wrote:The MiG-35 is supposed to get it as standard... and it has real 3D TVC unlike the Sukhoi models with 2.5D.

You are quite correct that the Al-31 was developed by Saturn - and so was the TVC.

GarryB wrote:You post a quote stating that there are two types of thrust vectoring engine, one is 2D and the other is 3D and then you say by canting the 2D type you can achieve 3D flight performance.
I know from experience you are not an idiot, but you can be a prick... which is what is happening right now.

You're not paying attention. The keyword here is "differential". I'll brake it up for you to explain it better.

Mir wrote:the canting allows roll and yaw moments by vectoring each nozzle differentially,

Mir wrote:thus enabling the aircraft to produce thrust vectoring moments about all three aircraft axes, pitch, yaw and roll.

All three axes = 3D.

This is what is known as "axis-symetrical" vectoring nozzles, and this is what Michail Simanov picked for his aircraft instead of 2D nozzles.

So no I'm not trying to be a prick here, I am just trying to explain how it works. It's really very simple but brilliant at the same time.

The boxy 2D TVC that was tested on the Su-27 showed that there was some IR reduction, but it was considered as not enough to pursue any further at that stage.

kvs wrote:They should stop at the addition of serration to the circular nozzles and not waste time with 2D F-22 style nozzles.   I have not seen any justification
for the need for such nozzles.    Escaping AA missiles?    But stealth does not work in the IR range.    The exhaust is always going to be hot enough
relative to the background to be detectable.    Mixing the exhaust enough to lower the IR by a large factor would require impractical large volume chambers.
Shaping of the nozzles is not going to do much without a large increase in surface area.  

Infact, I are of the opinion that the two squared nozzles are not for the air superiority version of the Su-57 but for the S-70 or alternatively for the two seat version of the same Felon, that would be tasked with controlling them or to perform strike roles.
You have however to note how nothing really forbid to mount such squared engines in the same way used in the Su-37 and the Su-57 i.e. slightly canted outward so to obtain the capacity to get a baseline 3D vectoring capability.

The Su-57 is not just a air superiority fighter - but as most of us know by now - it's also a troll machine

Bort number 053 was used to advertise the S-70. It even had the silhouette of the S-70 - acting as wingman - painted on the stabilizer with a Su-57.



Bort number 051 came with a pixelated paint job very closely resembling the latest patented shape of the Su-75 that was only very recently revealed!
055 had a similar shape as well.



Bort number 058 had an intriguing shape superimposed on a white background. Wonder what that could be? My first thoughts back then was that it was some Area 51 design but now I'm thinking it may well be Russian!

Bort number 058 had an intriguing shape superimposed on a white background. Wonder what that could be? My first thoughts back then was that it was some Area 51 design but now I'm thinking it may well be Russian! wrote:

PAK DP

I'm thinking the same thing but it's supposed to be a Mikoyan design? Then again we all thought the single engine light fighter project was a Mig thing - in the end it turned out to be the Checkmate from Sukhoi!

Mir wrote:The boxy 2D TVC that was tested on the Su-27 showed that there was some IR reduction, but it was considered as not enough to pursue any further at that stage.

I expect it also resulted in a thrust penalty which the RuAF decided against.

I've mentioned it before but here is a more simplified explanation for clarity:

Two-dimensional (2-D) vectoring nozzles gives control in a single axis, or pitch-only.
Pitch is the up and down movement of the aircraft from it's center of gravity.

Three-dimensional (3-D) vectoring nozzles gives you pitch, roll and/or yaw control.
Roll is the side to side movement of the wings from the aircraft's center of gravity.
Note that only two planes (i.e. pitch and roll) already gives you 3D vectoring.
Yaw control is an additional but extremely useful bonus - esp in aerial combat.

GarryB wrote:But the smoke and mirrors deflections of 2D angled nozzles to achieve what essentially would be a simple deflection to the left by both engine nozzles to yaw the aircraft would be complex and not as effective as to engine nozzles deflected 15 degrees to the left or right.

You need to look at these two short videos of the Su-57 in a controlled flat spin. It's yaw control in the extreme and I don't know too many aircraft that can do this

This particular controlled maneuver (360° of yaw around the center of gravity within the aircraft) is impossible to perform using only aerodynamic control surfaces. You need 3D TVC for that.
So no - there is no "smoke and mirrors" involved here and it looks extremely effective!  

First video shows the spin 30 seconds in whilst the other one shows it at 39 seconds. You can also look at Combat Approves series on the Su-57.




Here is also an interesting picture of the TVC nozzles on the older AL-31FP. Have a close look. The newer AL-41F1/S series uses the same principle and the same also applies for the AL-51's.

GarryB wrote:That is true for a single engined fighter.

Apparently the F-22 only has 2D TVC's - so how would you explain that?  
(just joking)

Anyway I see in your post above you completely ignore the controlled flat spin performed by the Su-57. A maneuver that can only be accomplished by 3DTVC's.

This is something that the Su-30MKI/SM, the Su-35 and the Su-57 can do. Not forgetting the Mig-29OVT as well.
I have mentioned before that the sole Mig-29OVT is one of my favorite Migs and I am well aware of what it can do.

To elaborate on the picture I posted of the AL-31FP engine nozzles - here is something interesting from the Su-57 series on Combat Approved:
(please note the subtitles)


From the up position going down...


...but they can also move from side to side  


So it's not only canted but the nozzles can also move a bit from side to side as well. In your parlance it should make it 3.5D then?  
Watch the series if you don't believe me.

What's more is that all these Sukhois are atm the only fighter aircraft in service with 3D TVC's.

Mir wrote:Apparently the F-22 only has 2D TVC's - so how would you explain that?  
(just joking)

Anyway I see in your post above you completely ignore the controlled flat spin performed by the Su-57. A maneuver that can only be accomplished by 3DTVC's.

This is something that the Su-30MKI/SM, the Su-35 and the Su-57 can do. Not forgetting the Mig-29OVT as well.
I have mentioned before that the sole Mig-29OVT is one of my favorite Migs and I am well aware of what it can do.

There are many inaccuracies in your posts, but the bottom line is that the AL-31FP, AL-41F-1S, AL-41F-1 and Izdeliye 30, or AL-51F engine, are all using 2D TVC. In other words the engine nozzle is deflecting only in one plane (up and down).
Also, flat spin can be performed without TVC and here is the practical example of that:



The plane in question is former Su-37 that had new, improved FCS installed, but the engines with the TVC were removed. That is the reason they have used the old Su-35 nomenclature. The same/improved FCS is used for the Su-30MK/SM versions and that plane can also do all those maneuvers without TVC, only at slower rate and with some AoA restrictions.
Su-57 can also do all those maneuvers without TVC, but with the TVC engaged the plane has faster initial rotational rates and better controlability.

The reason Su-57 has extremly fast rotational rates during flat spin lies in the fact that the plane is also directionally unstable. Using TVC and LEVCON's in conjunction, the plane can initiate rotation much faster than any other plane because they provide massive moment arm, and directionally unstable plane can react much faster than the one that is stable. For the same reason pilot can arrest the rotating motion much faster and efficient.
Since the nozzles are canted, differential nozzle deflection can create roll and yaw motion, but if you want just to isolate yaw motion for example, you need to counteract the rolling motion, since the differential deflection in this case is actually producing corkscrew effect/motion.
Planes inteligent FCS is using aerodynamic surfaces to counteract the rolling motion, so that the plane can only initiate the yaw motion.
What people don't understand is the fact that the TVC is just controlling mechanism, and most of rotation at moderately low speeds is done using lift and inherited instability of the plane. TVC is initiating the maneuver and latter controlling and negating all unwanted side slip that would cause the plane to enter uncontrolled spin.

When we look at the Izdeliye 30 mechanic parts of the nozzle, we can see that the deflection is only possible in one plane, up and down:



There are only two actuators at each side of the nozzle that move the whole nozzle up and down. They are connected to ring sealant (the part with the small holes) whose shape is made in such a way that it doesn't allow the 3D movement.
Here is the video that shows how it works:



Here is the true 3D nozzle that was proposed for the Su-57 engine:



You need three main actuators for the full 3D nozzle, and we can clearly see that this nozzle is having three of them. It also needs to have additional actuators for the supersonic part of the nozzle, and here they are made in the shape of the letter Y.
This is solution first implemented by the ФГУП САЛЮТ company on the AL-31F:



Here are the reasons I think Su-57 designers opted for the canted version of the 2D TVC nozzle, and for the full 3D TVC nozzle.

First, such solution is much more simpler with less moving parts, which is beneficial for the jet engine life cycle and ease of maintenance.
From the RCS perspective, it is much more easier and efficient to have less moving parts and intersections.
Also, the engine plume is uniformly putting the pressure on the nozzle walls which is not the case with the full 3D nozzle, and one of the main problems for the 3D nozzles in general was exhaust plume leakage.
Also, as can be seen, 3D TVC is less efficient regarding metal angle and plume angle deflection. You can have for example 15 deg. of metal angle deflection (nozzle deflection), but the plume deflection is always less than metal deflection.  
Next, we can see plume spikes with 3D TVC deflection, and that is additionally reducing plume/thrust efficiency.  

In this video at 19:40 we can see how 2D TVC AL-41F-1S plume is perfectly following nozzle deflection without deformations and additional spikes:



And since you have two widely spaced engines, you can create 3D TVC effect with canted differential nozzle deflection and clever FCS.
As a matter of fact, if we compare the Su-57 to J-10B with full 3D TVC, we come to conclusion that not only that the J-10B is not superior, but inferior in high AoA controlability and in nose pointing capability/rate. Also, fighters with one TVC engine can not create rolling moments, you need two engines for than, and while the 3D TVC is beneficial for the one engined plane, there are not many advantages compared to the two engined fighter with widely spaced, canted 2D TVC nozzles.

In the Su-57 patent, it is described how 2D TVC is working to create 3D TVC effect, confirming that the engines are 2D TVC.
Sukhoi official have stated that there is an option of the full 3D TVC for the Izd.30 that can be used for the Su-75, and that is probably the nozzle from the combat approved episode.