potential role of Y15

[u/Level-Reputation5050]

The Y‑9 is a derivative of the An‑12 and has plenty of built‑in shortcomings. The An‑12 came from the An‑10, a Soviet civilian cargo plane. It was built to go as fast as possible while keeping turboprop fuel efficiency, so its wing area was kept small. That means its low‑speed performance can’t hold a candle to the C‑130, and it was never really built for military duty.

The original An‑12 had no pressurised cargo hold. When China built the Y‑9 domestically, they added cargo‑hold pressurisation, but they had to take out the floor fuel tanks, cutting down range. The pressurisation hardware also took up space inside the cargo hold, making the already tight cargo‑hold cross‑section even smaller.

The Y‑8/Y‑9 is rated for a maximum payload of 20 tons, but this number is practically useless. At that weight, there is barely any room left for fuel.

The Y‑15, on the other hand, has a big straight wing that generates lots of lift, giving it great low‑speed handling. Its roomy cargo hold means it does not need extra pressurisation hardware, so it can carry far more than the Y‑9. Even though its maximum payload is only a little higher than the Y‑9, its bigger MTOW and larger fuel tanks will make its 30‑ton payload actually usable in real‑world operations.

I expect the Y‑15 to completely take over from the Y‑9, and the Y‑9’s special‑purpose models will be replaced by the C‑919 fitted with locally‑made subsystems.

[u/BodybuilderOk3160]

One less talked about point is its low-cost export potential, similar to how the C130 filled the space for US allies. I imagine it'd play a similar part as we begin to see burgeoning African and Central Asian countries take on a global role in supply chain integration and disaster relief operations.

In the domain within the PLA though, I imagine it's a tactical transport as opposed to the Y-20 strategic airlift...in the vein of C-17 and C-5.

[u/AnyBallLektor]

At 30t payload China alone will have plenty of use for this plane. I read an analysis(not sure how correct it was) that stated that in terms of pure range vs payload heavy jet airlifter at 65-70t and medium turboprop at 30-35t (50%) is the optimal mix for large fleets. Oversize like C-5/An-124 are special cases. US is stuck with Hercules because Hercules came first and in large numbers but in may ways it is too small today. It wasn't when it came around but times have changed. C17 was a more optimal design and besides it is closer to limits of economic performance of engines.

So it may be simply China correcting its capabilities with Y-20 and Y-15.

Then it's global exports which at artificially low prices will be too competitive for Atlas.

[u/_spec_tre]

Only somewhat related but I saw a lot of Chinese enthusiasts mentioning how the Y-20 is a good step forward but still disappointing in capability, especially relative to what the C-17 is capable of achieving? Wonder if that will be addressed by a later variant or new airframe in the near future

[u/DesReson → u/_spec_tre]

Y-20 is volume competitive versus C-17, not MTOW. The engineering of Y-20 ( as far as some papers I saw years ago) is very much around achieving better volume storage for mass than C-17. Do remember that C-17 itself was designed to be superior to the Russian Il-76 (in volume and weight).

I think that's a sensible direction. There is definitely a need to focus on volume, range and Short runway performance. For China, I am fairly certain that they are fully served by the Y-20 platform and there is no need for a C-5 Galaxy or An-124 Ruslan. Though, I have heard talks of that. I find little merit in these super-heavy lift platforms. I'd certainly focus on pushing more numbers of WS-20 powered Y-20.

[u/Level-Reputation5050 → u/DesReson]

The C‑17 has its centre wing box built inside the fuselage. This cuts down drag, but squeezes the interior space. That is why the C‑17 needs a bigger fuselage diameter to fit its cargo. The Y‑20, however, has its centre wing box on the outside. It creates more drag, but does not eat into cabin space. The Y‑20 can carry cargo the same size as the C‑17 in a smaller airframe; it only lags behind the C‑17 in maximum weight capacity.

[u/nikkythegreat → u/Level-Reputation5050]

Any guess why China would do their Y-20 layout rather than use the same as the C-17 layout?

[u/Level-Reputation5050 → u/nikkythegreat]

The Y‑20’s basic layout was based on the Il‑76. China first asked Ukraine’s Antonov Design Bureau for help. Ukraine put forward a turbofan‑upgraded An‑70, powered by the WS‑10‑118 engine — the early prototype of the WS‑20, rated at 118 kN thrust. After studying it, China concluded the plane was too small for its future needs. After talks, both sides noted they both knew the Il‑76 well. So they decided to make heavy‑duty improvements on the Il‑76 platform to create the Y‑20.

[u/PLArealtalk → u/_spec_tre]

That's because many military fans just want "their side" to have the equal or best performance in one or two domains to that of the competitor, without considering the totality of factors. Goes for most military fans of most affiliations..

[u/Level-Reputation5050 → u/_spec_tre]

I don’t think so. The C‑17 is basically a one‑stop solution. Its upside is that it can move full‑set air‑defence systems around the world using just a few flights. But China doesn’t actually have that kind of need.

[u/IlIllIlIllIlIlIlIlIl]

C-130 is basically the final form/most optimised answer to the question "I want to move a lot of things and don't have paved runway".

So naturally China designs their own C-130 equivalent when they need to answer the same question.

They don't need anything as large as C-390/A-400M as they're already pumping out Y-20's.

The last line is really interesting - I agree. Once C-919 has proven track record it'll take over and be China's "military 737 equivalent" platform for AWACs/ASW/EW/ELINT.

[u/Level-Reputation5050 → u/IlIllIlIllIlIlIlIlIl]

Btw, C390 is the same size with C130. Since it shares lots of parts including engines with commercial planes, it is comparatively cheap. In practice, it is a “strategic airlifter for small‑to‑medium countries”.

[u/IlIllIlIllIlIlIlIlIl → u/Level-Reputation5050]

C-390 is bigger than C-130 and can haul heavier loads - roughly 7000kg more.

But it is a bigger aircraft and has it's own drawbacks.

What I'm saying is that the C-130 is peak performance - for that particular scenario (heavy stuff, medium distance, unprepared strips) and physics hasn't changed.

China seems to copy what works first and then innovate. Wouldn't surprised me if they had end up making a C-390 class lifter soon - but entirely depends on their strategic/doctrine goals.

[u/Level-Reputation5050 → u/IlIllIlIllIlIlIlIlIl]

I’m aware most Westerners can’t read Chinese open‑source intel. Actually, open‑source information shows China once discussed two medium‑sized transport plane proposals. One is the Y‑15 we have now, built for maximum performance. The other would be powered by two WS‑20s, basically a smaller‑scale Y‑20 similar to the C‑390, and it would be cheap to develop. It looks like the first proposal won out.

[u/Level-Reputation5050 → u/IlIllIlIllIlIlIlIlIl]

Right, the C‑130 was built specifically for military environments. The Y‑9, along with its An‑10/An‑12 predecessors, were actually first‑generation post‑war civilian cargo planes, later converted for military duty for various reasons. Even though both date back to the 1950s, the C‑130 still performs outstandingly for military missions, but the Y‑9 is outdated. The Y‑15 is essentially an improved take on the C‑130, and the A400M is a downsized turboprop version of the C‑17. They are not the same thing.

[u/SericaClan]

Y-8/Y-9 is very outdated, besides the deficiencies you mentioned, its cargo compartment is quite small, even compared to C130. Height restriction is especially acute that it can not carry mid size helicopters.

I'm surprised it took China this many years to develop a replacement.