PLA next/6th generation fighter thread

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latenlazy

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Blitzo said:
Given the timeline for when the 6th gen fighter has been described as intended for service, I imagine they should be pretty darn close, unless they've gotten much faster with development cycles (and even then, this aircraft is likely to be the most challenging fighter aircraft project yet, or even the most challenging aircraft project yet).
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I think they’re probably still defining requirements to be honest, given that a lot of 6th Gen combat concepts are theoretical. I would place where they currently are as the stockpile R&D phase to have well developed and mature options for when requirements are finalized. Insofar as aerodynamic design is concerned they’ve probably gotten as far as winnowing down which configurations and control theories offer the best and broadest improvements in control and performance envelopes. When the requirement commitments are made development will probably be a lot quicker than what we saw with the J-20 because of the deeper and more mature R&D pipeline.

Edit:The other thing to keep in mind is that the flight and aerodynamics phase of development are typically the most time consuming.
 
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Blitzo

Blitzo

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latenlazy said:
I think they’re probably still defining requirements to be honest, given that a lot of 6th Gen combat concepts are theoretical. I would place where they currently are as the stockpile R&D phase to have well developed and mature options for when requirements are finalized. Insofar as aerodynamic design is concerned they’ve probably gotten as far as winnowing down which configurations and control theories offer the best and broadest improvements in control and performance envelopes. When the requirement commitments are made development will probably be a lot quicker than what we saw with the J-20 because of the deeper and more mature R&D pipeline.

Edit:The other thing to keep in mind is that the flight and aerodynamics phase of development are typically the most time consuming.
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I know.

And I'm saying that as of now in 2022 given the timespan in which the aircraft is expected to enter service and the likely development and testing time, I would be surprised if they haven't already basically settled on an aerodynamic configuration that they find satisfactory.

I would argue that subsystems integration and testing is more time consuming, for modern fighter aircraft.
 
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latenlazy

Brigadier
Blitzo said:
I know.

And I'm saying that as of now in 2022 given the timespan in which the aircraft is expected to enter service and the likely development and testing time, I would be surprised if they haven't already basically settled on an aerodynamic configuration that they find satisfactory.

I would argue that subsystems integration and testing is more time consuming, for modern fighter aircraft.
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I think subsystems integration and testing is *more important*, but by nature they’re quicker and easier to test, even if you have more of them. Anything involving the mechanical engineering component of hardware just requires a lot more operational legwork and each test parameter will tend to require more work to collect your data, and also much longer to do re-designs for. For example, flight control development and engine integration requires a whole lot of flight hours, but most avionics work can be done on the ground or in a lab until you’re ready to fly them for final integration and performance validation. A lot of test time factors are tied to tolerance and variance factors, and tolerance and variance factors are just wider and harder to control for mechanically related components than electrically related on.
 
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Blitzo

Blitzo

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latenlazy said:
I think subsystems integration and testing is *more important*, but by nature they’re quicker and easier to test, even if you have more of them. Anything involving the mechanical engineering component of hardware just requires a lot more operational legwork and each test parameter will tend to require more work to collect your data, and also much longer to do re-designs for. For example, flight control development and engine integration requires a whole lot of flight hours, but most avionics work can be done on the ground or in a lab until you’re ready to fly them for final integration and performance validation. A lot of test time factors are tied to tolerance and variance factors, and tolerance and variance factors are just wider and harder to control for mechanically related components than electrically related on.
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I think the nature of modern fighter aircraft is such that the advancing complexity of subsystems integration and developmental work has outstripped the advancing complexity of aerodynamic development and testing.

That said, I suppose if we are including the time needed for powerplants as being part of aerodynamic development, then it may be true. Though I would consider that as part of subsystems development, myself...
 
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latenlazy

Brigadier
Blitzo said:
I think the nature of modern fighter aircraft is such that the advancing complexity of subsystems integration and developmental work has outstripped the advancing complexity of aerodynamic development and testing.

That said, I suppose if we are including the time needed for powerplants as being part of aerodynamic development, then it may be true. Though I would consider that as part of subsystems development, myself...
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Even so, complexity of design does not always translate to complexity of testing, and complexity of testing does not always translate to length of testing time. The specific physical attributes of the systems, not the design complexity, plays the largest role in shaping test time factors. To give an example from real life, at my day job we have spent 6 months so far testing and retesting a single mechanical assembly that’s far from the most complex component in the product we’re working on, but because it has very unforgiving tolerances we have spent far more time on that than on other parts of the product’s systems that are more complex in design.

In the case of flight and aerodynamic development, flying the plane through various conditions, covering all flight parameters and flight envelopes, figuring out the minutiae of unanticipated conditions in your control theory, and then doubling back on the mechanical performance of the airframe from your flight tests are all just test work that take long hours. In the span of time taken to test one set of conditions for flight you can probably get through several sets of conditions for your avionics. System design complexity is not the primary factor here. Prepping for a plane to fly just requires more logistical legwork than prepping your electronics suite to buzz and ping.
 
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phrozenflame

phrozenflame

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latenlazy said:
I think subsystems integration and testing is *more important*, but by nature they’re quicker and easier to test, even if you have more of them. Anything involving the mechanical engineering component of hardware just requires a lot more operational legwork and each test parameter will tend to require more work to collect your data, and also much longer to do re-designs for. For example, flight control development and engine integration requires a whole lot of flight hours, but most avionics work can be done on the ground or in a lab until you’re ready to fly them for final integration and performance validation. A lot of test time factors are tied to tolerance and variance factors, and tolerance and variance factors are just wider and harder to control for mechanically related components than electrically related on.
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Here in lies how quickly China catches up the cutting edge or perhaps its somewhere there e.g. How US basically adopted F1 style manufacturing into its NGAD programme where a lot of testing and integration was done digitally.
 
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