Just out of curiosity, the kids at VTech purportedly plugged the J-20 into software designed to estimate mass and volume from photographs in order to construct a 3D model. Given that we have a substantial trove of photographs, wouldn't it be possible to do the same with the J-20 and F-22 and get their respective estimated volumes?
J-20 - physical parameters and other overflow from main thread
- Thread starter latenlazy
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manqiangrexue
Brigadier
Sure it would! I don't think it's too difficult for hardcore techies to develop a program for that. But nobody here seems to have even that minimal level of skill much less the skill it requires to actually attempt to guess what J-20 could weigh with any accuracy. That's why we can really only rely on reports; the level of analysis here is really just for fun. Do you have the VTech numbers?
Quickie
Colonel
That is how it should be done, instead of having a subjective judgement of the probable sizes and shapes based on one or two pictures and then amazingly come out with a number when there's no input of numbers in the first place.
Quickie
Colonel
It's still okay to base the estimation on the same assumptions, even if just for comparison sake, until more information is available.
For a start, with the little info that is available, the estimations would be still interesting to know.
I never presented my estimate as anything other than that. Nonetheless, estimates may have different methodological weaknesses.
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.
The YF-23 had an empty compartment with doors where the bay was, but no missile launching equipment.
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.
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.
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.
Demonstrator =/= prototype. The former is merely a proof of concept.
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)!
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.
Hyperwarp
Captain
Incorrect. YF-23 only had a weapons Bay compartment and demoed the bay doors opening during trials. It did not have any kind launch mechanism since it was not part of the ATF requirements.
YF-22 having a functional launch mechanisms and the decision to launch AIM-9 and AIM-120 was Lockheed-Boeing's own prerogative. It was to build confidence with the USAF and not because it was part of the ATF requirements.
Lockheed pulled few similar stunts during the JSF competition. X-35 Doing things beyond the requirements as confidence building measures.
The decision to build the F-22 remains the right decision, just as China's decision to build the J-20 remains the right decision,, these two unique aircraft are each "scratch built" to suit their own countries unique needs and desires...
as LockMart has been in the L/O business very seriously since the late 50's,,, they have a body of knowledge to pull from! Chengdu has been very impressive getting up to speed, and innovative in their execution of the J-20.
Equation
Lieutenant General
Easy there Brat, them SAC (Shenyang Aircraft Corporation) boys and girls doesn't like it when you ignored them and accomplishments.
I think Shenyang has done a very fine job on the FC-31. Point town though.Easy there Brat, them SAC (Shenyang Aircraft Corporation) boys and girls doesn't like it when you ignored them and accomplishments.