Found this on Quora. IMO good analysis.
Has WS-13 engine evolved enough to be mass produced and being used in JF-17 Block-3?
Boven Tan, Aviation nerd, especially on Chinese fighters.
Answered Nov 8, 2017
Yes and No.
First,JF-17s are equipped with RD-93 currently.
RD-93 = RD-33 moving gearbox to the bottom.
WS-13 is the intended domestic engine for JF-17.
WS-13 = licensed RD-33 + redesigned former fans. Slightly increased thrust, shorter service life.
WS-13’s development was behind the plane itself. It first ignited back around 2000, and took first flight test as late as 2010 on a JF-17. There were intense flight tests between 10~14, and the engine’s design and testing were finalized around 2015.
So technically, YES. WS-13 is a ready product and can be produced for JF-17 if needed.
But, still, NO. I don’t think current WS-13 will go on JF-17s.
First, there are still RD-93 in stock.
Back in the late 90s, when JF-17 was finally getting in the fast lane after a decade’s up and downs, China had already realized how difficult it is to develop modern jet engines, and experienced a major fighter develop failure due to the problem with engines.
Since JF-17 is a crucial platform for Pakistan, both sides decided to use a matured engine to get the project going, hence, the RD-33 was chosen and developed into RD-93.
RD-93 insured the success of JF-17 in such a short time, without it, there’s little chance to deliver the planes before WS-13 was done.
But RD-93 is provided in a particular way. First Russia exports RD-93s to China, and signs agreement that allows China to then re-export them to whomever it wishes. In this case, Pakistan.
This avoid direct deals between Russia and Pakistan, thus it’s technically all big bad China’s fault if India gets upset, which is OK by China because India gets upset about it literally all the time.
So China is holding the engines before they are exported again for JF-17, since no other plane in China uses RD-93 (and the same for WS-13), there’s no point producing WS-13s to replace it while the stock lasts.
As for the stock number? Different reports said different numbers on RD-93 orders during the years, but most said 150+ at least. With this number, there’s really no hurry changing to WS-13 for current JF-17s.
Second, for Block III, WS-13E would be preferred to the base model.
Block III was said to be planed with WS-13, but I always suspect ChengDu and PAF never stopped evaluating better options.
The reasons are clear. New avionics are more power hungry, especially the planed AESA, you need to draw more power from the engine. Unfortunately JF-17 is already a little under powered with RD-93, its’ TWR is slightly under 1.0 for a fighter, and the 3.7-ton payload is not optimal for air support missions, especially considering the newer L-15B and FA-50 can carry well over 3.5 tons despite their smaller air frame.
WS-13E might just be the solution. It pushes the thrust to 9500 Kg level, while reduces engine weight, thus the engine’s TWR is substantially improved.
WS-13E achieved this by redesigning RD-33’s chamber, and adopting new turbine design from Klimov on RD-33MKM.
The interesting thing is that RD-33MKM is said to adopt WS-13’s former fan design too, AECC and Klimov are working closely on RD-33 series that WS-13E and RD-33MKM are almost the same solution with different executions.
The development is going smoothly so far, it had entered flight test in late 2016, so if things goes normally, it could be expected to be ready by 2019.
In fact, I think the “WS-13E” theory can well explain what takes Block III so long, considering AESA and WS-13 are already on-shelf options now. If it’s waiting for a better engine, it actually makes much sense.
Chengdu can use the time to tweak the structures, maybe adding more hard points to take advantage of increased thrust, pushing payload well over 5 tons.
For PAF, Block III is a needed upgrade but not as urgent as the base model back then, they probably like this upgrade done right, rather than rush it out, knowing something better is likely just 1~2 years away.
Of course, there's another possibility, that WS-13 series are shit and in development hell, all we know about it is pure advertising bullshit from AECC, hence the long wait.
Well, at least we can still buy RD-33MKM then.
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