Shenyang / Chengdu "6th Gen" Aircraft - General Discussion and Speculation

[Avimimus]

Yes, the GCAP features substantially improved power generation capability compared to previous generation fighter aircraft. Nevertheless, my personal assessment is that a peak generating capacity of 1 MW is still too conservative for the J‑36, considering that according to leaks, the J‑36 places heavy emphasis on electronic warfare. Both its large airframe and two‑seat configuration are tied to its EW requirements.

The WS-15 is expected to produce more power than the WS-10... having three engines means 50% more power... and not all systems will scale in their power draw the way radar or jammers will. So, even without improvements in the ability to draw extra power from the engine - we're still talking about an 150% more power than a late model J-20 and 200% more power than an early model J-20. So it could still be a major increase in capacity even without taking any additional steps to draw more power from the engines.

Given the implied power to weight ratio and relatively limited thrust requirements in cruise they could probably add additional mechanisms to draw power from the engines... which would increase those numbers further - but I don't think it is necessarily implied that they will need to in order 'place heavy emphasis on electronic warfare'. That said, if they did plan a modified engine to allow increased electricity production... ...I wonder if the reason for the dorsal engine placement is partly to fit a larger heat exchanger for cooling electronics?

 

[bennyp]

Doesn’t the beam attenuate towards the edges of the radar? I’d imagine there will be some tradeoff form looking at head on targets.

I dont really see that as a concern. If you think of the total system then instead of each ship staring forward, each ship simply covers adjacent ships' sectors (total fused picture makes this a lot less confusing than in the past). When you bring in other offboard sensors into the picture like CCAs, AWACS, and legacy platforms, this becomes even less of an issue. Instead, it seems advantageous to me that the ownship arrays would be tailored for immediate tactical needs, and sidelooking arrays seem smart in that regard.

 

[Scott Kenny]

Doesn’t the beam attenuate towards the edges of the radar? I’d imagine there will be some tradeoff form looking at head on targets.

I'm not sure, not enough of a radar nerd to understand that.

It's my understanding that the overlap between the two arrays at ~45-50deg ~90-100deg eliminates that issue.

Edit: used sweep angle, not full included angle between arrays.

 

[F119Doctor]

Not sure I like starter-generators inside the spools, that's going to greatly suck for maintenance.

The classic "starter-generator in the inlet bolted onto the front of the compressor" like J34 and J79 may be a better option (not sure how well or even if that works with a multi-spool engine). @F119Doctor can you start a multi-spool engine by starting the LP compressor?

A two spool turbojet, maybe. A two spool turbofan is unlikely since a lot of low spool airflow bypasses the core and doesn’t assist the turning of the core. The F100-100/200/220 (0.7 BPR) requires approximately 350 KIAS speed to perform a windmill air start. I doubt a low spoil starter motor could match that level of airflow to the core rotor.

That said, there is a lot of discussion with starter / generators mounted on both the low and high spools, primarily to provide additional electrical power for aircraft systems without overly loading the high spool. Could a low spool starter help the high spool starter? Would take a ton of current to operate both.

 

[Scott Kenny]

A two spool turbojet, maybe. A two spool turbofan is unlikely since a lot of low spool airflow bypasses the core and doesn’t assist the turning of the core. The F100-100/200/220 (0.7 BPR) requires approximately 350 KIAS speed to perform a windmill air start. I doubt a low spoil starter motor could match that level of airflow to the core rotor.

I was afraid of that.

That said, there is a lot of discussion with starter / generators mounted on both the low and high spools, primarily to provide additional electrical power for aircraft systems without overly loading the high spool. Could a low spool starter help the high spool starter? Would take a ton of current to operate both.

Still means two starter-generators in very hot places that are an absolute nightmare to repair or replace.