I never presented my estimate as anything other than that. Nonetheless, estimates may have different methodological weaknesses.
They're still estimates; and methodological weaknesses can be compensated for.
In what respect? I'm assuming the *same* density, not more, and do end up with the J-20 having a bigger increase in fuel capacity than in OEW.
That the J-20 is denser than the F-22 prototype.
The YF-23 had an empty compartment with doors where the bay was, but no missile launching equipment.
Point given.
Wrong. It implies a half ton weight increase on the Flanker test bed. That says nothing about the F-22 (see below).
It's not a case of US technology being better - the Russians can probably teach anybody a thing or two about TVC - but it's an apples to oranges comparison.
Have you looked at the sheer size of that thing? It was a tech demo for the T-60S *bomber* (having a much larger engine) with IR signature reduction the primary goal - hence the very long duct and cooling air inlets. A fighter-style rectangular TVC nozzle (such as the F119's or that implemented by Soyuz on the R79 for the planned production Su-47) would have been heavier than an axisymmetrical nozzle for all the reasons you state, yes, but certainly not by several hundred kg. Count on it.
Here, you're accusing the Sukhoi engineer of dishonesty. Note that he was talking about TVC work in the late 1980s, when the modified airframe with 2D TVC flew in 1990. Moreover, the engineer is discussing the choice of 3D TVC over 2D TVC on the Flankers. If you're talking about the bomber TVC system, the Sukhoi engineer is comparing a 3D TVC, which was never discussed for the bomber, with 2D TVC. It stands to reason he's discussing TVC for the AL-31, not for the bomber engine.
The best argument for much lighter F-22 nozzles, in my estimation, is not bashing the Sukhoi engineer, but the presence of ceramic matrix RAM on the F-22's nozzles. It suggests that the Americans were able to achieve what Sukhoi could not, i.e, the use of "carbon-carbon" inside a ceramic shell. This is, on the other hand, just speculation. Also, for size, please do take a look at the F-22's nozzles themselves, which are not insubstantial.
Nope, it won because it was more mature and less risky, so had a greater chance of entering service on time & within budget. Although the YF-22 was considered more agile thanks largely to TVC, the YF-23 was judged to meet the desired maneuverability criteria even without - in the same way as the YF-23 rated higher on stealth but the YF-22 was still adequate. With both designs satisfactory in technical terms, they went with the one which promised a smoother development process.
Except that the F-22's development project was heavily delayed and its production variants had hypoxia issues, often lethal, for its pilots. But that's a dig and not really relevant, while your comment is an accurate correction, but it is not relevant to the fact that the YF-22 was more agile than the YF-23, and impressed evaluators, suggesting greater structural reinforcement
What stands to reason is that you are not going to build a demonstrator which will never fly more than a hundred hours to last 6000+h. It's not just the maximum g-load, but how long you expect to operate the aircraft.
Your point about lesser airframe life on the YF-22 is accepted, but the other reasons for high structural weight are not. The YF-22 conducted high AOA flight, first, second, the YF-22 had a working weapons bay that would have added on weight. Only lesser airframe life would account for lesser structural weight on the YF-22, but this can't justify the 30% weight increase between the fighters.
Demonstrator =/= prototype. The former is merely a proof of concept.
Point-ceded.
The C919 also has almost twice the fuel capacity (so - ex payload - similar fuel fraction), a wing aspect ratio of ~10 as opposed to 2.2 (hence a lot less induced drag) and *way* lower engine SFC (BPR of 11 against 0.6). The only things the J-20 has going in its favour are disproportionately lower payload (i.e. considerably less than half that of the C919) and wetted area (parasitic drag - though with the J-20 wing being more than half the area I'm not sure how big the C919's disadvantage from its fuselage is).
As for the F-15C, that's *theoretical* range with drop tanks *and* CFTs *and* no weapons, but fuel weight is so high in that configuration that it's actually an overload condition (it would be possible to top up from a tanker after take-off, but that kind of defeats the purpose). Take on only as much fuel as the MTOW limit allows and range reduces to 4800km, and then only if the drop tanks are punched off once empty to shed the drag. Nonetheless, a F-15C in that config *carries its own weight in fuel*, giving it an insane fuel fraction (better than even a 15t J-20 with any realistic internal fuel capacity)!
I'll come back to this in an edit.
As has been pointed out several times now, RAM is merely one of many components in the weight difference between the YF-22 and F-22, and responsible for only a small part of the total. It's a fundamentally flawed premise to operate on, by far the biggest sources of error in the VTech weight estimate are the weighting multipliers (as I stated) and the outdated dimension information used.
Basically, we're making an assumption that the light F-117 RAM paint reflects the light RAM on the F-22, when the F-117 is significantly less stealthy than the F-22 by -10 to -20 dBsm. RAM composites on the F-22 do not merely have to be paint.
