The mystery surrounding the J-10’s powerplant – WS-10 or AL-31FN ???

[Deino]

Hi guys … I just call for help as I once again have a problem this time regarding the J-10’s powerplant !

During last few weeks after the unveilance of the J-10 a new “fact” seems to have been accepted regarding the WS-10 powering at least the early prototypes esp. the picture showing several prototypes in a row !


But let me start with a “history as we accepted it until now” !!

Although it was believed to be powered initially by a 27,560lb/12,500kg thrust AL-31FN turbofan, a modified AL-31F which itself powers Su-27/J-11, Russia reportedly had denied China the license to produce the engine locally. As the result, an indigenous engine (WS-10A) may be fitted later during the serial production.
…
The development of J-10 has not been smooth. A full-scale mock-up was built in 1993. High-speed taxing occurred in 1996. The first prototype was set to fly in 1996, powered by a newly designed WS-10 turbofan based on the CFM56 engine core technology. However the development of this indigenous engine suffered some serious difficulties and thus the rear fuselage and engine intake were forced to be redesigned in order to accommodate an alternative AL-31FN engine imported from Russia. After a 15-month delay, the first prototype (01) made its maiden flight on March 23, 1998, two years behind the schedule.
…
China also signed a $300m contract in August 2005 with Russia to acquire 100 improved AL-31FN-M1 turbofan engines with bigger thrust (132.4kN) and TVC in both pitch and yaw, a design similar to that of RD-33OVT. This suggested that an improved version (J-10B?) may have been under development.

http://cnair.top81.cn/J-10_J-11_FC-1.htm

My first idea to that was: We’ve seem the WS-10 on a J-11 and it shows clearly recognisable differences to an AL-31 – regardless on the Su-27 or J-10 – as it has a completely different nozzle. Now some – even some of the well informed members at several other forums – state, that the original WS-10 has some very close similarities to the AL-31FN and can only be distinguished by a slightly longer/wider metal ring around the rear section. Latest suggestions say that on earlier prototypes – with that ring there are also some strange “bubbles” on top of the air-brakes.

My first argument against this theory – esp. as I didn’t find any source on that – was:

Even if I can't get a closer look "inside" it's quite possible to distinguish a specific engine on a military plane by a look at its nozzle: like a F100 powered F-16 from a F110 powered one; the same especially for the first RB.199 powered Typhoons from the serial EJ.200 powered. And so on ! Every modern engine has its typical external characteristics ... and no two engines especially from two very different manufactures look so similar like these Shenyang WS-10A and the Saturn AL-31FN exhausts !

If the J-10 uses a WS-10 it will surely show a different nozzle.

Therefore I still ask myself 2 questions: ???

1) If the WS-10A is actually based on the core of the CFM.56 as reported and we assume that the engine shown on the J-11/WS-10-testbed is then a "prototype" with not the final arrangement ... would it be possible to adopt the AL-31's nozzle ???

2) Otherwise if both engines do use the same nozzle and are only distinguishable by the length of the metal ring ... could it be that the WS-10 then is more related to the AL-31F as I thought before (like the WS-13 to the RD-93) ???

Therefore IMO the differences are much smaller than between an F100-PW-200 in an F-15 and a late F100-PW-229 in an F-16.

... what led me to three conclusions:

1) this is not the WS-10A !!!! ... or ...
2) both engines are closely related ... or do at least use the same exhaust design ! (Why; I don't know)
3) both engines are the same (= AL-31FN's) ... maybe from another production block and therefore show minimal external changes ... changes on the rear part of the airframe and not on the engine !

 

[Deino]

Part 2 !! ;D

Several posts later – still without an explanation and I started to make a simple “cut & paste” attempt with a serial AL-31FN onto the early prototype 1003 now supposed to be WS-10-powered !

To my own surprise there are in fact some noticeable changes … but more to the airframe, the tail and that ring and not so much to the nozzle:


Then yesterday the latest possible external differences between an early J-10 supposedly powered by the WS-10 and the later AL-31FN powered serial machines appeared in form of two distinct “bubbles” above the lower air-brakes + the wider metal part:


... the first two pictures (pic. 02 + 04) are from that one early prototype (1005 ???) repainted for Zhuhai 2006 with the bubbles on the air-brakes and the wider metal part = WS-10 !!

... and the third (pic. 01) one looks like a production AL-31FN-powered machine ...



Therefore by looking at the bubbles + the width of the metal part we could recognise: Only the earliest prototypes do show the wide ring + bubble characteristics:

All the planes with the wider ring do have the “bubbles” ---> = maybe WS-10-powered !
All the planes with the shorter ring and without the “bubbles” ---> = AL-31FN-powered !



Which concludes to All machines from 1001 (the white prototype) to 1009 show the wide ring + bubbles and were powered by earlier AL-31FNs or the WS-10 … only later prototypes from 1013 on have the shorter ring + later AL-31FN.

But this again opens another question and maybe an answer to a, statement made by crobato at the “sinodefenceforum”:

The prototypes with WS-10 satisfy one glaring question I had before. How can the Russians be able to modify and manufacture the engine so quickly you can have it delivered in 1997 so a J-10 prototype can fly it in 1998.

The answer: they didn't. The first AL-31FNs were only delivered after 2001.

Therefore crobato once again had some interesting thoughts regarding the first AL-31FN deliveries …


So … long statements, many pictures … just to conclude the issue:

Maybe I missed something !: What was the reason that appeared to say that these are WS-10 ??? … we already knew these pictures from the early prototypes – some of them for years – we were speculation when and if ever a J-10 was powered actually by an WS-10 !!!

But just take a look ! …. Any comments ??

Cheers, Deino ???

 

[overscan (PaulMM)]

I believe every J-10 pic I've seen to date has an AL-31FN. The earlier prototypes have the prototype AL-31FNs from Saturn. The later prototypes have the series AL-31FN from Salyut.

Now, there are a number of possibilities.

1) The article is wrong, for whatever reason; perhaps the journalist misunderstood the reply.
2) The first 5 J-10s were built in 1993-1996 period with WS-10. They were later (1997 onwards) reengined with AL-31FN. All the photos to date are post 1998, so we have not yet seen the J-10 with WS-10.
3) WS-10 exhaust looks like AL-31FN, but WS-10A is significantly different. Perhaps WS-10 stole the AL-31F afterburner section from production AL-31Fs and mated it with the hot section derived from CFM-56 reverse engineering?

At this stage we don't have enough information.

 

[Deino]

I believe every J-10 pic I've seen to date has an AL-31FN. The earlier prototypes have the prototype AL-31FNs from Saturn. The later prototypes have the series AL-31FN from Salyut.

Now, there are a umber of possibilities.

1) The article is wrong, for whatever reason; perhaps the journalist misunderstood the reply.
2) The first 5 J-10s were built in 1993-1996 period with WS-10. They were later (1998 onwards) reengined with AL-31FN. All the photos to date are post 1998, so we have not yet seen the J-10 with WS-10.
3) WS-10 exhaust looks like AL-31FN, but WS-10A is significantly different. Perhaps WS-10 stole the AL-31F afterburner section from production AL-31Fs and mated it with the hot section derived from CFM-56 reverse engineering?

At this stage we don't have enough information.

Completely agree with YOU as these are the only possibilities ... additional to maybe
4) the WS-10 is actually more related to the AL-31 than known !

But let me add two questions:

reg. 1) Do You know the original article which is the "source" of that "the WS-10 poweres the J-10" !
reg. 3) .... would this be possible ?? To add the AL-31FN's burner-section + nozzle onto the WS-10's core ??

Again this led me to another "mystery":
The WS-10A is said to be slightly fatter than the AL-31FN and also the first WS-10 ... I always thought this is also the reason for that strange break from the relative wide/fat aft fuselage to the narrower burner section and that huge gap between tail-base and nozzle !

But even on the latest J-11B pictures reportedly equipped with the WS-10A the nozzle looks identical to the AL-31F’s and not wider as seen on that prototype/testbed. ???

Deino

 

[elmayerle]

If the WS-10 is based on CFM-56 core technology, things get really interesting since the CFM-56 shares much of its core in common with the F101/F110/F118 family of military engines.

 

[overscan (PaulMM)]

The source is the J-10 issue of Ordnance Knowledge (the one posted in huge scans on China Defense.com Forum) apparently. I *think* it might be here:

http://www.china-defense.com/forum/uploads/post-8-1169049803.jpg

Evan, yes, China acquired two CFM-56s in 1983 allegedly for testing for civilian refits which were mysteriously "lost" in a fire. The theory is that they hoped to reverse engineer a fighter engine by studying its core, which is as you said F101/110 derived.

 

[Deino]

Hmmm ... so I think it would be interesting and helpfull to redraw the history of the AL-31FN !

When was the development contract signed ?? .. maybe a hint for problems of the original WS-10.
When were the first engines delivered ... and how many ??

... ohhhh what wonderfull times ! :

Cheers, Deino ;D

 

[Mike Pryce]

I think that the differences in the fairing 'ring' of the engine (the nozzles themselves are clearly identical on all aircraft) could be down to attempts to improve airflow around the rear fuselage during development. The fairing looks like it is there because the engine is narrower than the fuselage was designed for - which along with the intake looking a bit small and 'bodged' again indicates a bigger engine is/was intended. If the AL-31 is an interim engine they may also have shifted its mounting fore and aft for balance reasons during development.

If the WS-10 is based on the CFM56 then I guess its core airflow would be in the region of 130-170 lb/sec. (based on mass flow/bpr figures from http://en.wikipedia.org/wiki/CFM_International_CFM56). With a bpr around 0.4-0.6 the total mass flow can be estimated. Anyone got numbers for AL-31?

The blisters (bubbles) could just be added/moved equipment around the jetpipe.

 

[overscan (PaulMM)]

Indeed. The earlier prototypes look more as if an engine with a smaller diameter than intended has been used; it looks a little odd. The later prototypes look a bit smoother.

AL-31F mass flow is 110kg/sec.

 

[Tam]

This was probably the first plane spotted with the shorter metal ring. It lacks a number, and the nose is all metal and primered yellow, meaning it got no radar but flight telemetry equipment. When the first FC-1 flying prototype flew, it also had a metal nose, albeit painted with black enamel and had no static stripes.

Note this is when the J-10 first "officially" flew in front of Jiang Zhemin (said to be the major patron of the program and the guy who ordered its high priority secrecy). The nose of the plane had static strips, indicating an actual radar, not flight telemetry equipment. This really should not be the real first actual flight, but a prepared one. That means the plane had done flight telemetry tests before, and had passed that stage so they have fitted a radar on it to begin avionics testing. The pic makes Jiang Zhemin rather youthful, and in fact, this test pilot shown also appeared in later pics, and he has grown a belly and a few grey hairs since then. The pic gives credence to the article that the 1998 flight was probably one cooked up for the officials and wasn't the real one at all.

 

[sferrin]

Indeed. The earlier prototypes look more as if an engine with a smaller diameter than intended has been used; it looks a little odd. The later prototypes look a bit smoother.

AL-31F mass flow is 110kg/sec.

Interesting. The F110-132 is about 125kg/sec with the -100 and -129 at about 123kg/sec and the F100 and it's variants a bit less.


(Heh. The things you find while looking for other information "Combined cycle pulse detonation turbine engine operating method"
http://www.patentstorm.us/patents/6550235-description.html )

 

[overscan (PaulMM)]

First mention of AL-31F for J-10 I've found:

DATE:22/11/95
SOURCE:Flight International
Russians pursue engine and radar on Chinese F-10 fighter

CHINA'S CHENGDU F-10 fighter aircraft, being developed jointly with Israel, may be fitted with a Russian air-intercept radar and power plant.

Russian radar-design house Phazotron is proposing an advanced variant of its Zhuk (Beetle) multi-mode pulse-Doppler radar for the fighter, as the Israelis try to convince the Chinese to fit their systems.

Phazotron officials say that they are offering the Zhemchoug (Pearl) radar - described as a "development of the Zhuk, but with a better performance in terms of target detection range".

Previous reports on the development of the F-10 had suggested that the aircraft - effectively a continuation of Israel's Lavi programme, cancelled in 1987 would have an Elta radar.

The Russians also claim that the aircraft is to be powered by a single Lyulka Al-31F engine, two of which are fitted to the Sukhoi Su-27 Flanker. With a first flight expected as early as 1996, a power plant for the prototype will already have been selected and possibly fitted.

The Lavi was fitted with the 91.7kN (20,620lb)-thrust Pratt & Whitney PW1120 turbojet, although the release of the US engine to China is highly unlikely. A single Lyulka AL-31F produces 122kN of thrust with reheat.

The Chinese air force already has 26 Flankers in service, with a second batch of 24 believed to be on order. China has ambitions eventually to licence-produce the airframe and Lyulka engine. The latter would probably be produced by Wopen in Guiyang.

While the Chinese may in effect be holding a radar competition, the Israelis have run into serious opposition from the USA over the potential supply of advanced air- intercept-radar technology to the Chinese.

When Flight International first revealed in 1994 that the F-10 was a Chinese-Israeli collaborative programme, the US State Department announced publicly that it would examine whether Israel was in breach of US export regulations.

The US Government had been aware of the programme for several years and tried to get Tel Aviv to drop the project - the Lavi fighter programme having received much of its funding and technology from the USA.

The first pictures of the aircraft are reported to have been taken by US intelligence satellites in 1994, prompting US defence secretary William Perry to make a personal plea earlier this year to recently assassinated Israeli prime minister, Yitzak Rabin to drop the programme - without success.

The prototype of the new fighter is being assembled in a special site at Chengdu Aircraft, in Sichuan. In the late 1980s, at least 20 engineers from Israel Aircraft Industries (IAI) were part of the fighter's design team at Chengdu. IAI also helped with wind tunnel testing in the early design stage. The Israeli presence has been scaled down in the last three years.

The Israeli design and development input in the programme is valued at more than $500 million. Overall programme costs are said to top $5 billion.

 

[Tam]

I kind of wonder what exactly is the radar on that J-10 prototype.

 

[Tam]

Also its a good idea to keep a look out for more planes with flight telemetry noses. Either the plane nose is metal, primered but unpainted, or painted black to look like a fake radome, in which case it would have a shiny black enamel surface, but without the static stripes. This can mean prototypes with the WS-10A, AL-31FM1 and seeing a new one on an FC-1 can mean having the WS-13 Taisan engine on it.

On the radar it puzzles me, what slotted array radar did China have back in 1998 that you could fit on the J-10 01? Was the KLJ-1 even in service then? Was a Zhuk provided or is this an Israeli ELTA? The slotted array JL-10A was already on testing onboard the JH-7 084 prototype.

The sighting of a PL-11 on what maybe the wing of J-10 01 (the photo was shot right from underneath the plane), suggests its not a Zhuk. As the PL-11 is basically a Sparrow copy, this hints to a Western style radar, in which case possibly an ELTA or an early KLJ series type.

The radar on the 100X series of J-10 probably belonged to as KANWA reported, Type 1473 in PLA parlance, or KLJ-3 in its factory designation. The capabilities appear limited only to the PL-8 and the PL-11.

Not only the 101X series and with the J-10s that appeared with the Flight Test and Training Center did the J-10s started sporting PL-12s. This is probably a second generation slotted array, with a PLA parlance Type 149X, with X as an unknown number. There has been brochures of radars called KLJ-6 and KLJ-7, one of which may be for the J-10's.

This is in parallel with J-8II developments. The KLJ-1 or Type 1471 slotted array radar first appeared in upgraded J-8Ds and J-8Hs but only feature PL-5, PL-8 and PL-11 compatibility. Not until the J-8F with a new radar set that you have the PL-12 capabiltiy. A leaked inventory sheet reveals the designation Type 1492.

 

[Deino]

Hmmm ... is this the WS-10/WS-10A ???

 

[Tam]

Hard to say. Ths one has the nozzles that are more similar to the one in the original J-11 testbed.

 

[Matej]

Nice explanation of the engine puzzle with the photos: http://www.defence.pk/forums/china-defence/84838-new-j11bs-ws-10-engine-pics-2.html

 

[F-2]

Early WS-10 tested on J-10A