Knew I could count on you.
Dude can't hold his load in. It's an understandable affliction.
Chinese Engine Development
- Thread starter jackbh
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Dude can't hold his load in. It's an understandable affliction.
Yup, fewer airfoils vs. higher mechanical complexity and difficult sealing. As I said in that old post, I'm not sure it's worthwhile when with conventional, proven measures (variable stages, handling bleeds) there is probably some more performance left to extract from a traditional configuration. The EJ200 HPC is by now 30 year old tech and got a PR of 6.2 out of 5 stages without bleeds and only one stage of variable stators, GE and CIAM were bench-testing 6-stage HPCs for civilian engines with PRs on the order of 14 to 15 almost 20 years ago:
Since we're discussing the relative state of the Chinese aeroengine industry this graphic provides a decent overview I think. It concerns shorthaul airliner engines obviously but, the projects are running roughly contemporaneously and all relevant countries bar Japan are represented. Source: I updated the data because since the paper was published in 2016 more info has come to light.
Worth mentioning that the production PW6000 HPC actually derives from MTU's HDV12 in the left hand table. PW's own 5+1 compressor failed - to nobody's surprise really, it had by far the highest stage PR among a group of universally very ambitious projects. Others, like TRDD-2005 and TECH56, were superseded by designs with higher stage counts but lower stage PR in favour of higher OPR and better stage efficiencies based on increased kerosene price. Note how PW/MTU later follow this trend on the GTF, and SaM146 and PW6000 are really regional jet engines anyway.
No mention of 3D printing in the abstract though (in fact it states the part was machined).
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With engine capabilities up across the board, would the next PLA fighter after J35 move back toward single engine?
I don’t think so. Trend for sixth gen is towards heavy, long range jet. I think they’ll be twin engine heavy fighters the same weight class as today’s bombers/fighter bombers.
Advanced medium thrust engines will be useful on drones.
6th generation aircraft will be very demanding in terms of capabilities and requirements. All the advanced electronics systems will demand a ton of power. There's also a consensus that 6th gen should be faster, and operate at higher altitudes. As well as with what siegecrossbow said, next generational aircraft will demand much more power which a single engine may struggle to provide.
Even F-35's single engine is struggling to power the airplane because it's originally a light fighter but now it has the capabilities of heavy fighter. PLA better off making single engined loyal wingman UAV to complement two engined sixth gen heavy fighter.
I do wonder if the dimension of 6th-gen fighters will become significantly larger than current 5th-gen ones as well?
If the case is true, then they will certainly pose bigger challenges for carriers to field them. For example, perhaps instead of two F-35s can be carried per elevator at any one time, only one F/A-XX can be fitted per elevator at any one time. Or that while both F-35s can take off simultaneously on the fore catapult launch positions, only one F/A-XX can be launched at any one time using the same position on the flight deck.
So that means either carrier-based 6th-gen fighters need to be much smaller than their land-based counterparts, or that future carriers have to grow even bigger in size.
Yeah I think my only reservation with them going this direction is that it’s *extremely* ambitious but they seem to be giving the team working on this some press so they seem pretty committed on this path, at least for now. Tbh the papers I’ve been perusing for this design sounds a bit crazy. The airflow is already supersonic after the first stage. But they’ve also apparently been working on this concept for almost 20 years now, given the first papers that came out we’re in the early 2000s.
Yeah going with more stages just made a lot more sense for commercial applications once fuel efficiency and cost considerations were factored in. You don’t need high thrust to weight efficiency, so no point dropping stage count, and running each stage less intensely means less mechanical wear and longer parts life. I think with contemporary commercial applications these days everything about the engine cycle design probably involves a business optimization function.
That’s not what’s happening in this story. The F135’s propulsion is working just fine for the F-35. The issue here is the F-35’s other subsystems are generating more heat than intended in their design and the amount of bleed air the engine is designed to divert for cooling purposes is insufficient, so they’ve had to run the engine harder just to generate more bleed air to sufficiently cool the rest of the plane.
This is more a problem specific to the F-35’s design than to all future fighter designs in general. If anything, being a larger twin engined fighter would have likely mitigated these kinds of problems by spacing out hot components more to provide more volume for the heat to dissipate, and by having two engines to provide bleed air for additional cooling rather than one.