The giant J-36 design is indeed the dreamy one for most Chinese military fans, but a hypersonic strategic bomber of that size perhaps needs to be powered by four 7th gen rotating detonation engines, not even four vce can power it.
China has just tested the rde since the last 2 years, and it may need more time to refine it.
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I understand current tech does not allow us to develop a supersonic strategic bomber (intercontinental reach but for one way journey only otherwise China needs regional bases everywhere for return journeys).
I prefer a scenario where H-20 is the intercontinental ranged Ultra Low Observable bomber so keep the pure flying wing for just that little bit better stealth and longer reach. But also develop a JH-xx that has one way range to 2nd island chain (range) and combat radius (operation and return journey accounted for) to 1st island chain when taking off from between central and coastal China. Combat radius to 2nd island chain if taking off from coastal China. Supersonic design kills range but doable with what China has.
With the recent leakers discussing the test flight H-20's details, it sounds like a pure flying wing design. This means it is subsonic and the size suggests intercontinental range. There are actually other programs for supersonic strike aircraft that are around the same length but much thinner.
If JH-xx isn't for next generation and basically will become operational around the same time as H-20, it is going to be using existing engines. This isn't difficult since 4 WS-10 or WS-15 can easily take an optimised design to well past mach 2.5. The limit isn't the airframe but the engine compression staging and bypass ratios which even fighter optimised WS-10 and WS-15 can achieve around Mach 2.5. This is enough speed for JH-xx.
The mystery supersonic, large aircraft has sweep angle that indicates speeds >mach 3.5 though. It also doesn't appear to be able to support 4 WS-10 or even 4 WS-19. It is likely two engines and two WS-15 even modified to suit such a platform is unlikely to be able to push such a large and heavy strike aircraft to past even mach 2. Therefore this aircraft is testing with some other engine. China has tested many types of combined cycle engine in flights since 2019. The rotating detonation is still much more experimental compared to the turbofan - rocket and turbofan - ramjet combined cycle engines. Scramjets are used by the hypersonic cruise missiles YJ-19 and CJ-1000 and quite unlikely to be powering an aircraft because they require rocket boost to scramjet operating speeds. Same issue with ramjets, requires boost or combined cycle with turbofan in lower speed stages.
Therefore the engine used for this mystery aircraft is probably some turbofan - ramjet combined cycle and it's likely only two units.
Note that the GJ-xx which is now speculated to be a large unmanned tanker is B-2 sized in wingspan.
VCE will not be able to push this supersonic aircraft to the speed (mach 3.5+) indicated by wing sweep angle. In fact my measurements this sweep angle is more than the WZ-8 which is already a mach 4 aircraft at altitude. I suspect 2 units of combined cycle is the only way to push beyond mach 3. VCE will start struggling around mach 3 and is mainly great for fuel efficiency -> range.
