PAK FA, T-50: News #1

It seems that the aircraft Russia and India will be working on will be very much a new aircraft like the Su-30MKI program according to this article that suggests that the T-50 will not be "abandoned".

RF will not forego its own design of the fighter of the fifth generation

Russia will in parallel conduct the designs of the building of its own fighter of the fifth generation and analogous machine, projected together with India, reported on Thursday vice-premier RF Sergey Ivanov.

“We our project leave will not be. We will go forward in parallel”, said Ivanov to journalists.

He recalled that “[Rosoboroneksport]” and company “dry” in December plan to conclude contract with the government of India according to the design of the aircraft of the fifth generation, which will be produced for VVS of two countries.

In this case Russia continues the tests of its own analogous machine, it noted vice-premier.

To the beginning of November new domestic combat aircraft already completed 36 flights. In the course of tests the basic units of machine and the parameters of the work of engine are perfected, Ivanov reported.

“As yet there are no serious censures”, it noted.

Ivanov also confirmed that the second flying copy before the end of the year into air must rise on this project.

Russia and India agreed about the joint development and the building of the aircraft of the fifth generation, which completed the first flight in January of this year. It is assumed that will be created two versions of this combat vehicle - one-place and two-place. Frame contract for the creation of the fighter of the fifth generation was signed earlier. Expenditures it is planned to distribute approximately equally. Russia and India plan to create the fighter of the fifth generation to 2015-2016 (T -50 the Russian version of aircraft). It is assumed that the fighter of the new generation will begin to enter the Russian troops since 2015 (in the one-place version), and by 2020 it will appear in VVS of India.

T -50 - fighter of the fifth generation of heavy class with a takeoff weight is more than 30 tons, average dimensionality (approximately corresponding to aircraft Su-27), the being monoplane with the widely diverse engines and two keels, strongly deflected outside from the longitudinal axis. The exterior view of glider is designed with the use of technologies of geometric low observability “Stealth”.

The aircraft of the fifth generation is equipped with the fundamentally new complex of avionics, that integrates the function “electronic pilot”, and by promising phased-array radar. This to a considerable degree reduces load on the pilot and makes it possible to be concentrated on the fulfillment of tactical missions.

T -50 can take off and be sat down, using sections of the takeoff and landing strip with a length of 300-400 meters. Aircraft will develop the speed to 2,1 thousand kilometers an hour and accomplish overflights up to the distance to 5,5 thousand kilometers. Fighter is also equipped with the complex of inflight refueling.

Aircraft possesses large internal weapon bay. In it can be placed to eight rockets of the type R -77 of air battle or two enormous guided bombs with a mass of 1500 kilograms each. Fighter is capable during the external suspension to bear two rockets of the super-large distance of development by bureau “innovator”. By these rockets T -50 is capable to destroy aircraft, for example, of the type " AWACS ", at the distance to 400 kilometers.

“RIA of the news”

On November 25, 2010

It also mentions 8 R-77s can be carried internally too.
Note "dry" is the online translator translating "Sukhoi".

Those photos Vlad posts are from the 1980s and the Russian aircraft makers have had a lot more experience since then.

Such experiments have been viewed in the west as failures because the Su-37 and Mig-29OVT which are the only two Russian aircraft with thrust vector engine control (the Su-30MKI has it too of course) they used conventional round engine nozzles.

Obviously the use of flat nozzles will reduce thrust performance but also greatly increases the mixing of hot and cold air so it is better from an IR perspective and it is easier to make the engine nozzles stealthy when they are rectangular than if they are round.

The engine nozzles are separate from the engines so the very first T-50s will likely have rectangular engine nozzles and 117S engines and a re-profiled rear end to reduce RCS. When the proper 5th gen engines are ready... about 2020 or so, they will change the engine and may have to revise the rear end shape depending on the size and shape of the new engines but will still use rectangular engine nozzles.

The rectangular engine nozzles will probably have 3D thrust vector control and if they are effective enough there is a possibility that the horizontal tail surfaces might be removed as redundant.

This will reduce costs and weight and complication and RCS during manoeuvres. With 3D TVC they might be able to remove the vertical tail surfaces too which would further reduce weight and cost and RCS and simplify the design... though it might lead to problems of aerials for various systems not having anywhere to go.

IIRC it was the 90s, and they have done nothing since.

I am pretty sure I saw those photos in the late 1980s, but even if it was the 1990s they have said the T-50 will have rectangular engine exhausts so clearly the drop in thrust is seen as worth it for the improved RCS and IR signature.

This also suggests they did not abandon research on the subject. The fact that we have heard nothing is no great surprise because the other aircraft they have made with 2D and 3D TVC have not been stealthy aircraft so the cost in thrust is not worth the minor improvement in RCS and IR signature. Only with a stealthy airframe would such a sacrifice be worth while.

Such experiments were viewed as failures in Russia because they brought the plane's performance to unacceptable levels. It has nothing to do with TVC of others.

Perhaps what they meant was the that the improvement in RCS and IR signature was not significant for non stealthy aircraft while the loss of thrust was significant so it made no sense to apply rectangular exhaust nozzles to a non stealthy airframe.

We already know what the first T-50 engine nozzles will be, the same Iris nozzles on the 117S. When the new engines come, maybe something different. We are talking post 2023.

Austin posted something somewhere about the T-50 having rectangular nozzles and a redesigned rear end that was more stealthy for the in service aircraft. The prototype we have seen doesn't even have an IRST fitted but has the ball position for it... but we can assume that the in service Mk1 fighter will have an IRST installed and it wont be in such an unstealthy ball configuration, but rather some more angled stealthy design too.

Even the F-22 doesn't have 3D TVC... stop reaching.

The Russians seem to be every bit as capable with thrust vector technology. The more so when one allows for the fact that when the Americans wanted a 90 degree plus thrust vectoring nozzle that could handle full AB of a rather powerful jet engine they turn to Yakovlev rather than Rolls Royce. (RR making the pegasus engines for the Harrier series).

The ability to make a 3D thrust vectoring engine with a round tube is potentially harder than doing it with an engine nozzle with 4 surfaces. Improvements in technologies and materials and design suggest a 3D rectangular nozzle is not impossible.

AFAIK the F-117 had a rectangular nozzle for radar and IR purposes and has no thrust vectoring capability at all.

For the T-50 the addition in agility of thrust vectoring alone would be worth the weight and cost of a rectangular nozzle, the reduced RCS and IR signature are added but also very important bonus's. The simple fact of the matter is that leaving the engine exhausts as they are is like always carrying an external AAM on the aircraft. It ruins the efforts made elsewhere.

They didn't quit for a lack of application. IR reduction can be used on any fighter to survive thermal seekers. That is why it was tried with the Su-27.

The Su-27 was a testbed aircraft.

If you are suggesting that this is proof it was being developed for the Su-27 then I have a picture somewhere of the PAK DA... it is a Tu-135UBL with the radar of a Blackjack and a small external bomb rack used as a test bed aircraft and also as an operational trainer.

The PAK FA would therefore be an Su-30M because that aircraft was used to work on the radar and some avionics.

IR reduction and RCS reduction make more sense on an aircraft that already has a low RCS because a difference in effect of a few percent is not enough to warrant the complication and cost and the loss of thrust from rectangular exhausts. A circular nozzle can offer IR reductions simply by making the actual engine less visible.

It makes no sense for any fighter to give up 17% thrust and acceleration curves for slight reduction in an IR signature.

A stealthy aircraft with unstealthy engines doesn't make sense either. Aircraft don't always have the luxury of keeping their noses pointed at their enemies. In fact most of the time they will be facing away from some of their targets.

The RCS is the main thing but IR signature reduction is a bonus.

There is no redesign for the batch 1 production aircraft. There is no time. No new engines, no new nozzles, nothing new, just what can be fitted for pre-production batch by 2013. It has to be on time at all costs or the Indians will bail.

The TVC nozzle on the Mig-29OVT is not part of the engine, I don't see why a rectangular nozzle would need to be part of the current engine (117S). TVC engines will add weight, but for supercruise they will be very very important as they can trim the aircraft in supersonic flight without the need for control surface deflection which would increase drag.
Once they are developed, and we don't know what actual progress has been made in that respect, they could simply be retrofitted to in service aircraft, just like the TVC kits for the Su-30MKIs. To make them work you just need a software upgrade of the flight control system.
The aircraft the Russians build with the Indians will almost certainly need thrust vector control engines of some form. Rectangular nozzles will be better but round nozzles will do.

And manoeuvre capability with TVC will easily outmanoeuvre any aircraft without TVC even with high acceleration and more thrust.

We will see what the next batch of aircraft look like because it will be different from the prototype simply because that ball IRST is not stealthy so they will have to change it. What else will they change? I think if you look at the photo of the engine with the flat nozzle you posted above that has the engine covered all the way down to the nozzle area will be the change made to both engines on the T-50 even if they don't fit rectangular nozzles.

Considering we couldn't get step one right, no reason to take step four.

The fact they are talking about rectangular nozzles for T-50 suggests they have step one right. Even if the loss of thrust is 30% being able to redirect thrust is incredibly important.

BTW that thrust loss doesn't mean a 12 ton engine suddenly becomes an 8.4 ton thrust engine... it means when the TVC nozzle is fully deflected it generates 8.4 tons of thrust in that direction. At very low flight speeds that will still make an aircraft the size of the T-50 a very manoeuvrable aircraft, the widely seperated engines will allow differential turns of the engine nozzles to give an amazing roll rate and allow carefree manouver capability at low speeds, while at supersonic speeds very small deflections will not effect thrust performance much at all but will allow the aircraft to trim itself without using control surfaces that would otherwise cause drag. This will significantly improve super cruising speed and performance at supersonic flight speeds.

And I know well the F-117 was a bomber, not a fighter so WTH would they bother with TVC?

So rectangular nozzles are useful for IR and RCS reduction... so why wouldn't they bother to do the same on a fighter that is supposed to be a stealth aircraft too?

The simple fact is, it is beyond our capability for the near future. Revisit the topic in 8-10.

You make that claim. I say that it was tested in the 1990s and a lot of other work has been done with different shaped designs but at the end of the day they know a rectangular nozzle will be needed for any stealth aircraft to remain stealthy. And also because it is for a fighter that 2D thrust vectoring is a necessity and 3D is probably a wanted goal.

They have 5 years before this aircraft gets anywhere near service and probably 10 years before the final 5th gen engine is ready to go into the aircraft, but the engine nozzle is a separate thing from an engine and they can be developed separately so it is not a case of developing one for the current engine and having to make a whole new design for a new engine. Once designed it can be fitted to the current engine and adapted to the next engine too.

makes an interesting read

Before I even click the link... let me guess... America was too quick to stop F-22 production and Russia will sell PAK FAs to all the evil countries of the world and America will loose air superiority. Sky falling. We need to reopen the F-22 factories and start work on 6th Gen fighters.

Ha ha ha... sorry, just started reading that article Austin and it is even sillier than I thought it would be.

Apparently Syria will provide PAK FA stealth fighters to terrorists who will create their own air force to destroy Israel with.

Ha ha ha ha ha ha.

Perhaps in response the USAF could give F-22s to the Chechen rebels to form a state of the art air force to force Moscow to all for an independent Chechen state again...

I also thought this was funny:

Russian doctrine still considers the U.S. its “principal adversary,” even though successive U.S. Administrations have announced that Russia is no longer our enemy.

US administrations say a lot of things and most of the time they are not worth the paper they are written on. Actions speak louder than words and by her actions the US has clearly shown Russia is still the enemy.

Otherwise it seems to be a rehash of Kopps opinion about what the Russians might have and what it might be capable of.

I am an optimistic guy (Ask Vlad... ) but even I think this is a little too optimistic.

At the end of the day the sky will not fall, the world will not end... it is just that the US will have to do a little more planning before it decides to regime change some countries in future.

I think the important thing is that engines can be changed during overhauls and are not that big a deal. Engine nozzles can also be changed easily enough so even if all the new aircraft built next to accelerate the testing process have a particular set up that means nothing when it comes to what the in service aircraft will look like necessarily. If we see a stealthy faceted IRST and round nozzles then we can say that there is an issue with rectangular engine nozzles. Personally I think the only problem they would have is making it full 3D thrust vectoring because they seem to have mastered a round nozzle with 3D TVC already and presented it publicly.

Of course it could also be they want to keep the final aircraft design secret for as long as possible.

It is very easy to get 2D thrust vectoring with a rectangular nozzle, in fact it is easier than getting 2D thrust vectoring capability with a round nozzle.

The thing is that it doesn't matter if it is a rectangle or a hexagon or pentagon it needs straight edges to get the RCS benefits but a more complex shape than a rectangle would probably be easier.

The irony is that early stealth aircraft had straight lines and angles because the software was not sophisticated enough to handle curves... it seems they have hit a wall with a rectangular nozzle because if you think about it up and down is easy... look above at the photos... fixed side walls and flexible horizontal surfaces for up and down vectoring of thrust. The problems occur when you articulate the sides... you need to be able to angle the thrust up or down and to either side at the same time which results in the nozzle becoming a sort of snake like rectangular tube that is very complex that can still converge and diverge the thrust like a normal exhaust nozzle.
Perhaps a pentagon or Hexagon shape might prove easier, or they might just have to settle for 2D thrust vector capability and better flight control software.

agree with you
but i'm talking about 3D TVC with rectangular nozzle,,i think it's impossible..!

It is certainly not easy, but I wouldn't say impossible. A round nozzle is made up of petals that intermesh so there are no gaps when it opens out wide or closes in to a small tight hole (called convergent/divergent nozzle). There is no reason why a rectangular nozzle could not be made the same way so that the nozzle remains a four sided shape but that the sides of the nozzle can change size.

If you think about a rectangle and you shorten it on one side and extend it on the other opposite side you are basically moving the nozzle to one side from where it was. Doing it back the other way and you have 2D thrust vectoring. Being able to adjust it vertically at the same time is mechanically tricky but I wouldn't say impossible.

You could take it a step further and start from a round nozzle and say that it really isn't actually round because each of the petals are flat so instead of aligning the petals to form a round nozzle you could alter their angle and make the nozzle a geometric shape like a 10 sided shape, or an octagon (8 sided), or a Hexagon (6 sided) or a pentagon (5 sides). With the flat sides you might be able to get the RCS reduction and IR reduction without having to go to rectangular nozzles. You might actually find that triangular nozzles (3 sides) is actually even better than 4 for RCS and IR reduction and 3D vectoring might be easier with three sides.

so why russians leave RCS benefits??
i think russians alredy reduce RCS by making astealthy shape and composite materials to the pak fa,but round nozzle still increase RCS...
i think it's not necessary,,f35(5th gen.) althogh has round nozzle and low maneuverity than pak fa !!

I don't think they will spend billions of dollars on it, but if they can solve the problems having 3D TVC that is stealthy in radar and IR wavebands is something they want.

Think of a sniper in a ghillie suit with a bright shiny stainless steel rifle and scope. All the effort and disguising the shape and signature of the sniper is ruined because the same effort applied to the man wasn't applied to his kit.

There are shortcuts... weapons are carried internally because it is cheaper and simpler than making all the weapons stealthy.

The exposed area of the engines that make them look like the engine installation on the Flanker series suggests there is work left to be done at the rear of the aircraft. The fact that the engines are widely separated and angled outwards suggests first they wanted large internal weapon bays, but also that they wanted increased angle of momentum for TVC engines. By putting the engines further apart they increase the separation of the nozzles so when one nozzle is deflected up and one is deflected down it generates more rotational force on the aircraft. It is like a corkscrew. The wider the handle the less force you have to apply to the ends of the handle to turn it. If the handle was 1mm long the leverage would be tiny and it would be easier to twist the cork off with your bare hands. If the handle was 5-10cm it is easier to grip but the leverage means even the toughest cork can be defeated.

so,you mean russian will produce rec. nozzles in the first patch of pak fa??

I don't know. I would expect they would find 2D rectangular nozzles fairly straight forward because the issue of materials for diverting exhaust flow even in AB have been mastered in the Yak-41 and also in the engines for the Mig-29OVT and Su-30MKI and Su-30MKM and the Su-35 and Su-37.
Remember the main engine of the Yak-41 is in the 18-20 ton thrust class so it is a very powerful engine.

at your view: what are yoiu prefer:
# 2D TVC thrust with rec.nozzles(benefits here low RCS and low IR signature)...
or
#3D TVC thrust with round nozzles(benefits here high maneuver against enemy missiles plus more speed)..
...........

It doesn't matter what sort of TVC you have... dodging missiles requires excellent awareness of the incoming missile and really doesn't rely on a high g turn... when you turn 120 degrees in a cobra you basically stop in mid air, you don't suddenly start heading backwards at the same speed you were moving forwards at. You basically stall.
That was bad without TVC because you have no control till you get your aircraft flying nose forward and have air flowing over the wings and tail control surfaces so you can manoeuvre your aircraft.
With TVC you can use engine thrust to continue to point your nose where you want and continue fighting so to speak and you can manouver your nose down... accelerate and then fly away from the area whereas without TVC you have to just wait till your nose falls and you can accelerate and regain control.
Most of the weapons of an aircraft are still optimised to face forward. If you can't turn your nose at a target and fire your missiles then you are a spectator not a fighter.

Without TVC when you stall you are useless.
With TVC you might choose to enter a stall to suddenly change direction or to directly fire at a newly appeared target... it becomes just another tactic option.

Regarding your question ideally as a pilot you want to see them and have them not see you so giving up some manoeuvre capability for Stealth actually makes sense. 2D TVC is still TVC so you can do all those fancy post stall manoeuvres. Whether you have 3D or 2D is really only important to your flight control system which is doing all the work. For the pilot it makes some manoeuvres harder... you might need to roll the aircraft a bit before you can turn a particular way, but remember at normal speed you have all the flight control surfaces plus thrust vector control and also engine differential control as well to manoeuvre the aircraft.

At the end of the day if you see him and can shoot first you have an enormous advantage and the best chance of a kill, so I would take 2D thrust vectoring nozzles of lower RCS and IR signature over 2D thrust vectoring nozzles of higher RCS and IR signature.

is there any other techniqes to reduce ir signature of the engine ..instead of using rectangular nozzles????
sorry for language..

There are some exotic technologies I have seen mentioned where chemicals are sprayed into the engine exhausts... most of them refer to the B-2 bomber... being a large aircraft with room for that sort of thing.
In practical terms I know of two options... the obvious is to use a higher bypass turbofan. A turbojet engine is basically a tube with a shaft or several shafts down the centre linked together with fans on them... a big fan at the front to suck in cold air and in the middle where the tube narrows there are smaller higher temperature fans (where it narrows it compresses the air which heats it up... this is the high pressure or hot section... also known as the combustion chamber... where fuel is added and burned to heat it further) Then at the rear the tube widens to allow the hot air to expand and sometimes more fuel is sprayed here where it is called an Afterburner or reheat. A turbofan is like a big tube around this turbojet and the shaft from the hot section is connected to a bigger front fan that sucks air into the turbojet engine but also through the outer tube the air going through the outer tube is cold but also very dense so you get more thrust from it than from the thinner faster air through the turbojet. The air going through the outer tube is bypassing the hot thinner air going through the turbojet inner tube so it is called bypass air and when it comes out the rear of the engine because it is relatively cold it mixes with the turbojet air and speeds up cooling. Look at the engines hanging off a Boeing and you will see the big wide short fan at the front that is the bypass section and sticking out the back is the hot turbojet engine... this is a very high bypass engine that generates most of its thrust from the bypass air. The turbojet is just there to turn the big fan that blows a large volume of air.
These engines can have enormous thrust ratings but the thrust they generate is from enormous amounts of cold air not moving at high supersonic speed so the aircraft that use these engines can't fly past the speed of sound. For a military aircraft a turbofan engine is very good because all that bypass air is oxygen rich so the afterburner or reheat can be much more effective at generating thrust than with a standard turbojet.
The problem is that while a high bypass turbofan has a much lower IR signature than a low bypass turbofan or turbojet if you want to supercruise then you need very high exhaust velocities and you only get that from a turbojet or low bypass turbofan.
The best compromise would be a variable cycle high/low bypass turbofan where high bypass could be used for more efficient subsonic flight with low IR signature, but when supercruise or supersonic flight is needed it can operate in a low bypass mode as well.
The other method of reducing IR signature was using an armoured nozzle inside the exhaust nozzle as used on the Su-25 CAS aircraft. This conceals the rear of the engine hot section from view and it can be partially cooled by bypass air, but I rather doubt it could be used on a stealth fighter simply because it might make an afterburner impossible.
Obviously the talk about S shaped intakes so a radar can't see the front of the fan blades of the engine directly also apply to the rear having a big long snake like 3D rectangular engine nozzle might further improve IR signature.

From WSJ

China Clones, Sells Russian Fighter Jets

These reports come out on a regular basis, the thing is that the Russians have moved on. The aircraft they sold China were basically not much different from the Su-27SM. Certainly more advanced than the Su-27 base model, but also not Su-30MKIs either.
As long as Russia can stay a generation ahead I see no real problem.
The Chinese are trying to master and copy Russian material of a generation Russia probably can't sell now anyway. No one seems to be interested in buying Su-27SMs or Mig-29SMTs any more.

The Suggestion that China will suddenly steal all of Russias remaining markets is amusing to say the least. Russia has the problem that it has lost the market of the former soviet republics to a degree and eastern europe as well. Of the other Soviet customers few have much money and were better considered donor clients that accepted Soviet Aide. Russia has worked to cultivate new export opportunities and will continue to do so, but the idea that China will replace them seems a stretch when China continues to buy RD-93 engines for aircraft it exports to Pakistan. The RD-93 is an RD-33 with its gearbox shifted from the top to the bottom to suit the aircraft it is to be installed in. If they can't copy a jet engine from the 1980s then what chance of improving on it?

The reality is that China as an enormous population and labour is plentiful and cheap but most high tech stuff are not manufactured in sweatshops by kids earning a dollar a week so the labour advantage doesn't continue. Later on workers will start to realise they are being used and that pay and conditions are poor and they might start demanding better conditions and better pay for a better living standard.

China has enormous potential, but Russia has changed its market... it is going for high tech, while China seems to be more in the cheap and simple Soviet market.