J-20 5th Gen Fighter Thread VI

[latenlazy]

J20 is not approximatively of same volume as f22. I've myself calculated the volume to be some 20ish percent bigger. Now that doesn't need to be accurate, but it's fairly evident from the images that volume is bigger.

Images can be misleading. Planes are not exactly simple geometric shapes.

 

[Totoro]

Images can be misleading. Planes are not exactly simple geometric shapes.

well, i am talking about my own experience. No one must take my word as gospel. I know how much time i put into it, searching for perfect images to compare from various angles, breaking the planes down to smaller and smaller geometric shapes until i was confident enough to calculate their volumes and add them all up. I probably can't get a precise figure out of such measurements but i am personally (and again no one should just take my word for it) fairly confident J20 is around 20% voluminous than F22.

 

[latenlazy]

well, i am talking about my own experience. No one must take my word as gospel. I know how much time i put into it, searching for perfect images to compare from various angles, breaking the planes down to smaller and smaller geometric shapes until i was confident enough to calculate their volumes and add them all up. I probably can't get a precise figure out of such measurements but i am personally (and again no one should just take my word for it) fairly confident J20 is around 20% voluminous than F22.

I don't mean to dismiss the work you put into the conclusions you drew of course. If possible though, and if you have time, I'd like to see it, or at least hear you run through some of the particulars of what you did.

 

[FORBIN]

I don't think the 15000 kg figure is fully credible, and needs to be substantiated by further sources of independent credibility. But it's not wholly impossible; the J-20 is known to have a 40% weight reduction in its titanium airframe courtesy of Chinese 3D printing technology, and its volume is approximately around that of the F-22's.

Given the F-22 is about 40% titanium by weight, this comes out to a reduction of 3000 kg, or around 16000 kg for the J-20.

15 - 19 t sure closer 19 more big than F-22 no doubt

 

[Quickie]

well, i am talking about my own experience. No one must take my word as gospel. I know how much time i put into it, searching for perfect images to compare from various angles, breaking the planes down to smaller and smaller geometric shapes until i was confident enough to calculate their volumes and add them all up. I probably can't get a precise figure out of such measurements but i am personally (and again no one should just take my word for it) fairly confident J20 is around 20% voluminous than F22.

My opinion is that the images one should take should be very long distance telephoto shots. Short distance wide angle shots will totally distort the dimensions of the aircraft.

As an example, satellite images of the j-20 would give a fairly accurate relative dimensions (not the absolute dimensions though) of the overall shape of the J-20 in the plan view.

 

[siegecrossbow]

To assume J-20 is 4 tons lighter than Raptor without reason would be a stretch, but now, there is word from AVIC, the makers of the J-20, that that is the case. I'm not saying the reliability is indisputable, but that coupled with the many posts here that discuss how weight could have been saved (possible 3 ton loss on improved titanium alone, weight loss through DSI, omission of thrust vectoring, etc...) certainly makes the case for the possibility. Don't forget, the J-20 was designed specifically to be able to cope with inferior engines if needed. At this point, from what I can see, the only argument for why the J-20 could not possibly be that light goes along the lines of, "But USA couldn't make it that light 20 years ago! How could anybody do better than a 20-year old American design?" Well, that's called denial, not reasoning LOL Times are changing, and they change faster in China than anywhere else. Call it "extraterrestrial" if you want, but to many, the entirety of China's meteoric rise has seemed quite out-of-this-world.

That's done with aerodynamics, as can be inferred from Dr. Song's paper. Even though the J-20 managed to save weight through reduced vertical stabilizers, DSI, material, fabrication, etc, it still has internal weaponsbays and the accompanied mechanisms which are significant contributors to weight. I don't think that an aircraft of J-20's size has the proper structural integrity to maneuver like a fighter if its weight is around 15 metric tons!

 

[Inst]

The J-20 also has larger fuel volumes than the F-22, which imply that despite being greater in volume, more of this volume is empty space.

What makes this figure really weird, though, is that it seems to be implying that the J-20, with WS-15, can hit around 1.36 T/W fully loaded and in combat weight sport 1.67 T/W. That's less of an aircraft and more of a missile. Aircraft are typically limited by 9G human tolerance, so is the objective to achieve 9G at mid-supersonic velocities?

 

[Quickie]

That's done with aerodynamics, as can be inferred from Dr. Song's paper. Even though the J-20 managed to save weight through reduced vertical stabilizers, DSI, material, fabrication, etc, it still has internal weaponsbays and the accompanied mechanisms which are significant contributors to weight. I don't think that an aircraft of J-20's size has the proper structural integrity to maneuver like a fighter if its weight is around 15 metric tons!

Increasing the structural mass of the aircraft, to increase strength, also increases its overall mass which then contributes to higher G-forces.

So, its all about balancing the increase in structural strength without increasing the overall mass more than required, meaning that, it's possible that the same structural strength can be attained with less structural mass.

 

[manqiangrexue]

That's done with aerodynamics, as can be inferred from Dr. Song's paper. Even though the J-20 managed to save weight through reduced vertical stabilizers, DSI, material, fabrication, etc, it still has internal weaponsbays and the accompanied mechanisms which are significant contributors to weight. I don't think that an aircraft of J-20's size has the proper structural integrity to maneuver like a fighter if its weight is around 15 metric tons!

Well, it's done' with aerodynamics surely, but don't you think an equal amount of effort was placed on lightening the plane? Would it not be wise? The contributors to weight that you've mentioned are all on F-22 as well and we've already discussed how this plane could have been lightened 4 tonnes from F-22. If you bring internal bays into the equation to add weight, you are essentially comparing it to 4th gen aircraft which are made with much less sophisticated manufacturing techniques and heavier materials.

Anyway, I highlighted your last assertion in bold because I just could not understand how you might have arrived at that conclusion. The number of engineering calculations you'd need to perform and the level of mastery over material science required seems unfathomable to me at this point for someone to make a statement like that. How did you calculate this?

 

[kurutoga]

What makes this figure really weird, though, is that it seems to be implying that the J-20, with WS-15, can hit around 1.36 T/W fully loaded and in combat weight sport 1.67 T/W. That's less of an aircraft and more of a missile

I assume that WS15 can be heavier especially with the rumored all direction vector nozzle with stealth considerations.