SinoDefence Forum

Londo Molari

I am looking at the specs for both the J-10 and the flanker, and their top speed, range, payload seem roughly similar.

The only difference I can see is the # of engines.

Does anybody know why these 2 separate fighter programs are being pursued when their capabilities and roles seem so similar?

crobato

1. The J-11B has more hardpoints and total payload weight.

2. The J-11B has greater fuel range (possibly)

3. The J-11B has a greater radar range.

4. The J-10 is cheaper.

All these point to a high-low mix being pursued as a strategy by the PLAAF.

Plus,

5. China needs to subsidize both companies somehow.

Yang Yang

J-10 is a light fighter , it's used to defend the airspace
J-11B is a heave fighter , it is used to fight against the F-16s of Taiwan.

tphuang

huh? J-10 can't be used against F-16s in Taiwan? That's the first time I've heard of something like that.

You got the basic problem that even if they wanted to, they can't produce as many J-11s as J-10s.

Vlad Plasmius

Perhaps he means J-11B would be used to penetrate enemy airspace and gain superiority while J-10s would go in and maintain it.

dollarman

That makes no sense, as J-10 holds less fuel and therefore would have a shorter loiter time than the J-11B. Also, reserving specific tasks for specific aircrafts is stupid, especially when both fighters are multirole. Both aircraft would be used in any attack, because China does not have that many of either.

Pointblank

I would say it is more of a hi-lo approach, as seen with the USAF and their combo of F-15's on the high end, and F-16's on the low end.

crobato

The J-11B does consume more fuel, with having two engines and double the weight. But as we have discussed in another thread, drag does not go up proportionally with size and weight, so we can expect the J-11B's drag profile to be way less than 2x of the J-10's and each engine would be pushing much less drag than the J-10's single engine.

The J-10 is clearly meant to take the F-16s one on one. Personally I think the J-10 can handle anything the J-11B can do. The J-11B has greater payload and hard points so it can pack more "punch" per mission, but the J-10 will have a higher sortie rate (produce more missions) due to being simpler and easier to maintain.

PLAAF is settled on a high lo mix doctrine. Just remember one of the reasons for such a doctrine is to avoid putting all your eggs in a single basket if it turns out, by the experience of war, your doctrines proved to be wrong.

Londo Molari

Ah, I see. They are pursuing a high-low mix like american F-16/F-15.

So J-11B is superior to J-10 in terms of range and payload... I didn't know that.

Thanks a lot!

I thought they both have the same radar?

crobato

The radars for both are technological and same company siblings. This makes them roughly equivalent in technological level. But the one on the J-11B is larger, giving it an inherent advantage in detection.

tphuang

J-11B's radar detection is probably 30% more than that of J-10. But J-10 has much smaller RCS, so they probably balance each other out.

maglomanic

Just wondering where that 30% figure came from? Also if i am not wrong it was mentioned that J-11B has undergone some RCS treatment on intakes and may have an RCS of around 3 m^2. What are the numbers on J-10 RCS?

In any match up however i would expect both J-11B and J-10 to detect eachother beyond the range of their long range missiles.

crobato

From what we know the diameter of the J-10's radome is around 700mm. We know that by the size of the Zhemchug/Zhuk-ME radar Russians proposed to the J-10. We know that the Su-27's array is about 1m. That's public knowledge based on the N001E Myech radar. That's like 30% difference in array size.

However, its hard to conclude that will amount to 30% increase in detection range, because radar detection formulas don't work linearly. Not only RCS factors count (both J-10 and J-11B has RCS reduction measures) but the power of the emitter (TWT or traveling wave tube). There might also be differences in the electronics themselves and the radar design despite being siblings from the same company where I can expect much sharing of the internal components and software.

It is safe to say the J-11B may have a better detection range, but I won't give it a specific figure as to how much.

Once you're into a fight, and removing all ECM/EW factors, the J-10 has this for its advantage:

-Smaller size, harder to eyeball
-Nimbler
-has a faster roll rate (past 300 degs/sec vs. 220 degs/sec for the Su-27)
-faster instant turn rate (over 30 degs/sec vs. 28 degs/sec over the Su-27).

On the other hand the J-11B has

-IRST
-Greater TWR if the plane is 60% internal fuel and lower
-can sustain a fight longer due to having more fuel

As for hi-lo mix, I expect and in my opinion, that the J-11B might only be 1/3rd costing more than a J-10. There is a good sense of rationalization and commonality between the two aircraft that will lower the cost for both.

---Sharing similar avionics, ECM, radar sets, all reduce the cost of such
---Sharing the engines (AL-31, WS-10A). This rationalizes logistics, maintenance, lower initial purchasing costs with volume buys.
---Sharing similar weapons (PL-12, PL-8B)

tphuang

Oh, the 30% was just a guess. I don't know what 30-40% larger in radar diameter will result for detection range. This was just what I guessed based on Zhuk-ME vs Zhuk-MSE:
I think it was 624 mm vs 960 mm
And the range was 120 km vs 180 km. So, the ratio seemed to be the same.
But I'd love to read some technical stuff on this.

Scratch

Looking at the radarequation [sry, german text] (equations 10 and 12) I think the detection range increases linearily with antenna diameter.
Radius is quadratic in antenna area A, wich is linear in antenna gain G, wich is quadratic in the range R (12) that means radius is in the fourth dimension in R. But it's also in the fourth root. So that should be linear.?
Does that make sense, or is it even understandable ... ??

One point I like to mention is the important thing is not necessarily how J-11B and J-10 compare against each other, but again their common enemies. Most probably F-16s. But also -15, -18, ...
J-11B can detect them from farther away while J-10 can stay undetected for longer.
One thing that's also mentioned rather often is that Flankers could bring more kinetic energy. But I'm not sure if that's that important an advantage over the J-10.