J-20 5th Gen Fighter Thread VI

[Biscuits]

If PL-15 has a dual pulse motor and an AESA seeker those would be significant boons to its overall capability vs AIM-120D.

Specifically, the dual pulse motor means that its end game kinematics nearer to its maximum range will be more capable than traditional single pulse motors with higher kP

Not sure about the dual pulse motor but it uses an AESA seeker.

I doubt it’s cinematics at 180km would be any worse than the AIM120D at the same range even if it lacks the dual pulse motor. At 180km the PL15 still has juice for another 120km while the AIM120D is all out.

 

[ougoah]

It's as clear as day that 6 PL-15s will NOT fit in the current setup and with fixed fins. PL-15 has a bit more range but they are slightly longer than PL-12s and the bays cannot do the offset fitting because the length does not allow for it. Look at the actual available space rather than the panel length. There are structural elements tapering into the actual storage depth of the bay. J-20 will probably soon have MRAAMs that have ranges that are around AIM-120D/ PL-12 but either with retractable fins or clipped fins to fit either 6 or 8 into the bays. The range offered by these missiles should still be enough for J-20 which can exploit its LO to give those missiles more than enough NEZ. PL-15 and PL-xx are too thick or long.

 

[Deino]

I've given it up as a lost cause. Some people only see what they want to see.

Pardon in case I missed it, but with what part of Henry's report you don't agree?

 

[Blitzo]

Pardon in case I missed it, but with what part of Henry's report you don't agree?

I think he's talking about the first part of Hendrik's post which says "When ask to the performance of J20 the pilot said that J20 is as agile as J10. That should put and end to the myth that J 20 is underpower" -- i.e.: that regardless of Henry's report, people will still believe things about J-20 (interceptor/striker/not intended to be agile etc)

 

[Deino]

I think he's talking about the first part of Hendrik's post which says "When ask to the performance of J20 the pilot said that J20 is as agile as J10. That should put and end to the myth that J 20 is underpower" -- i.e.: that regardless of Henry's report, people will still believe things about J-20 (interceptor/striker/not intended to be agile etc)

Agreed ...

 

[Totoro]

There's little reason for the current j-20 engines not to be rated around 140 kn. If we're talking about true definition of agility (and not maneuverability) then it's all about mass vs thrust. Supersonic thrust is another matter, but subsonic one is mostly about engine power and weight.

If J-10 is 9 tons empty, with similar payload/fuel loadout, its 137 kn engine should provide for similar agility as if j-20 had the engine of same thrust, if it was 18 tons empty and had similar payload/fuel fraction. Which are all fairly realistic assumptions. If J-20 engines were specially uprated or are perhaps AL31FM2 variant, going up to 142 kn, then J-20 could be even close to 19 tons empty and still retain generally the same agility as J-10.

Now, J-10 might be closer to 8 tons empty... but somehow I find that unlikely, given how much weight have F16 and Gripen gained with their newer variants. Especially since J10 is slightly bigger. Actually, empty weight of closer to 10 tons might still be realistic for J10. In which case it'd be little wonder that J-20 would have (at least) the same agility as J10.

 

[Blitzo]

There's little reason for the current j-20 engines not to be rated around 140 kn. If we're talking about true definition of agility (and not maneuverability) then it's all about mass vs thrust. Supersonic thrust is another matter, but subsonic one is mostly about engine power and weight.

If J-10 is 9 tons empty, with similar payload/fuel loadout, its 137 kn engine should provide for similar agility as if j-20 had the engine of same thrust, if it was 18 tons empty and had similar payload/fuel fraction. Which are all fairly realistic assumptions. If J-20 engines were specially uprated or are perhaps AL31FM2 variant, going up to 142 kn, then J-20 could be even close to 19 tons empty and still retain generally the same agility as J-10.

Now, J-10 might be closer to 8 tons empty... but somehow I find that unlikely, given how much weight have F16 and Gripen gained with their newer variants. Especially since J10 is slightly bigger. Actually, empty weight of closer to 10 tons might still be realistic for J10. In which case it'd be little wonder that J-20 would have (at least) the same agility as J10.

I'm actually wondering about the J-20 having similar agility to J-10 statement a little bit.

I wonder if it is comparing a loaded J-20 with a similar payload and load of fuel, to a J-10 or if it is compared to a J-10 with a lighter payload.

as a 5th generation fighter J-20 should have a higher fuel fraction than a 4th generation fighter, and having its main weapons stowed internally should have significant benefits for reducing drag when conducting maneuvers vs a 4th gen fighter with an equal external load.


So I don't think the best comparison is thrust vs empty weight, but rather thrust vs loaded weight (or combat weight).

Also, is there a generally accepted idea that agility in aerospace is the relationship between thrust and mass? If not, then I think maneuverability or an aircraft's overall kinematic properties can qualify as "agility" as well (in which case it doesn't simply become a matter of thrust and weight but also the more complex aerodynamic design properties of each aircraft).

 

[latenlazy]

I'm actually wondering about the J-20 having similar agility to J-10 statement a little bit.

I wonder if it is comparing a loaded J-20 with a similar payload and load of fuel, to a J-10 or if it is compared to a J-10 with a lighter payload.

as a 5th generation fighter J-20 should have a higher fuel fraction than a 4th generation fighter, and having its main weapons stowed internally should have significant benefits for reducing drag when conducting maneuvers vs a 4th gen fighter with an equal external load.


So I don't think the best comparison is thrust vs empty weight, but rather thrust vs loaded weight (or combat weight).

Also, is there a generally accepted idea that agility in aerospace is the relationship between thrust and mass? If not, then I think maneuverability or an aircraft's overall kinematic properties can qualify as "agility" as well (in which case it doesn't simply become a matter of thrust and weight but also the more complex aerodynamic design properties of each aircraft).

It’s the relationship between thrust, mass, lift, and drag. People use thrust and mass as a simplified proxy because thrust provides the total energy for every maneuver and mass is what’s being moved, but a simplification is always just that. In the case of comparing the J-20 with internal carriage and a J-10 with a similar combat load that drag component should be a major consideration.

 

[Totoro]

Everyone defines stuff differently, that's part of the problem. I happen to define it this way: Maneuverability is capability to change the direction of movement of object within function of time. Agility is capability to change the position of object within the function of time. Other people can define it differently. Lots of people happen to conflate agility and maneuverability as one and the same. I happen not to.

I REALLY don't want to comment further on other stuff as we have too little info on how much aerodynamics influences what at which speeds. Same goes for drag generation. It's next to impossible for us to approximate the effects of a larger body compared to smaller body and outside payloads. So lets please not go there.

 

[latenlazy]

I REALLY don't want to comment further on other stuff as we have too little info on how much aerodynamics influences what at which speeds. Same goes for drag generation. It's next to impossible for us to approximate the effects of a larger body compared to smaller body and outside payloads. So lets please not go there.

That doesn’t mean it doesn’t matter though. Just because this stuff is complicated and impossible to determine as bystanders doesn’t mean we should just pretend it doesn’t exist, especially when these are the actual factors that matter most when we talk about stuff like maneuverability and agility. If they could just be put to the side while preserving any meaningful asssessment then everyone would just be flying bricks of different mass and different thrust.