J-20 5th Gen Fighter Thread VI

[manqiangrexue]

For a fake you seems a good

Well, I learned form the best, just to make post #653.

PS. What type of "English" are you using now? Italian accent? LOL

 

[latenlazy]

Maybe but i wait since a while an answer for J-20 agility and him provide...others talk provide Nothing !

The sentence with 3 words as Delft posted means nothing only critics.

There is an answer. It's called the original design paper for the J-20's design by the J-20's designer, Song Wencong. I'm going to go out on a limb here and say the actual design study for the plane, written by the plane's designer, will tell you a lot more than someone with at best an idiot's guide understanding of flight mechanics.

b787's contributions boil down to unsubstantiated conjectures built on a shoddy and contrived understanding of the subject. If you desperately want to know whether there is life on other planets and someone gives you made up pseudo-science that sounds like an answer would you believe them? Critique is not nothing. It's how we grade someone's homework so we don't fool ourselves into believing things that are factually wrong. The measure of truth is whether an argument or claim stands up to scrutiny, not whether someone offers an answer that's personally satisfying to you.

If you want an actual informed discussion about the J-20's aerodynamic properties I dug up some old posts on keypublishing from i.e. (who seems to have disappeared) talking about the design a while back. I'll repost them here later when I get the time.

 

[FORBIN]

Well, I learned form the best, just to make post #653.

PS. What type of "English" are you using now? Italian accent? LOL

You quote me in first and we know the feeling... except trolling are you able do other things it is a question
recently one play and he finish on the wall, i don' t have quote you in first so you stop or ...
Good day

 

[FORBIN]

There is an answer. It's called the original design paper for the J-20's design by the J-20's designer, Song Wencong. I'm going to go out on a limb here and say the actual design study for the plane, written by the plane's designer, will tell you a lot more than someone with at best an idiot's guide understanding of flight mechanics.

b787's contributions boil down to unsubstantiated conjectures built on a shoddy and contrived understanding of the subject. If you desperately want to know whether there is life on other planets and someone gives you made up pseudo-science that sounds like an answer would you believe them? Critique is not nothing. It's how we grade someone's homework so we don't fool ourselves into believing things that are factually wrong. The measure of truth is whether an argument or claim stands up to scrutiny, not whether someone offers an answer that's personally satisfying to you.

If you want an actual informed discussion about the J-20's aerodynamic properties I dug up some old posts on keypublishing from i.e. (who seems to have disappeared) talking about the design a while back. I'll repost them here later when I get the time.

Thanks ok

 

[manqiangrexue]

You quote me in first and we know the feeling... except trolling are you able do other things it is a question
recently one play and he finish on the wall, i don' t have quote you in first so you stop or ...
Good day

OK, you can save face. You want the last word in to look like you won but you don't wanna get crushed back so you write something incomprehensible and thus impossible to answer? Good deal LOL

 

[FORBIN]

OK, you can save face. You want the last word in too look like you won but you don't wanna get crushed back so you write something incomprehensible and thus impossible to answer? Good deal LOL

Others guys pay you as an attorney i quote Figaro initialy they are not able defends themselves so low and you think necessary do it but it is not your business young guy... you have begin i finish
But again good day

 

[manqiangrexue]

Others guys pay you as an attorney i quote Figaro initialy they are not able defends themselves so low and you think necessary do it but it is not your business young guy... you have begin i finish
But again good day

I cannot be an attorney. I am unfortunately too honest and kind

 

[FORBIN]

I cannot be an attorney. I am unfortunately too honest and kind

Me also

 

[vesicles]

Maybe but i wait since a while an answer for J-20 agility and him provide...others talk ( not all ofc ) but provide Nothing !

The sentence with 3 words as Delft posted means nothing only critics and thanks to the report finally i know ( about) for agility !!!

You think is intelligent again talk about that for again have the mess here ? ...

Not sure if you've noticed my exchange with b787. He proposed a theory on the wing area. I asked him for proof. I begged him to show his proof. However, he simply refused to show any actual data. He still hasn't given me the measurements and still insists on "eyeballing". In fact, he made fun of me and joked that I was being rude when asking him for numbers.

So he's actually the one who provides nothing.

 

[latenlazy]

Thanks ok

In case you were interested.

Hi all,

watching this thing for a while, finally decided to comment*
Couple of comments, then I will watch the fireworks.*

1) This thing may have big (-10%Mac) negative static margin for transonic speeds. this also should help out with L/D at supercruise speeds.*

2) for close coupled big canards/LEX/DeltaWing combo, 1+1+1 > 3. thus on the planeform side you may will see over all a smaller lifting surface (higher onpaper wing loading) than the other two.*

3), comment 1)+2) should tells you bit about what the idea is for this design. longitudinal wise: try to get good nose pointing ability, good energy turns, and good cruise drag, at same time and affordable price.*

4) On T-50: T-50's wing-body design relies on channel flow between two big engine booms. not entirely with out problems, imho. draggy. the name of the game is always L/D and LEVCON is not necessarily better get your a better L/D. and it does have its drawbacks. and LEVCON certainly can not beat canards at high AOA nose down pitching moment generation.*

5) DSI may not be that bad with supersonic pressure recovery, all depends on how you design it and where your critical speeds are.*

6) This thing may well turn out to have distributed hydraulic/ EHAS.*

7) ah those dreaded ventral fins. my guess is lateral stability at high aoa ( and high mach) may be border line with the two smallish VT when they did their tunnel and cfd studies. and the canards are naturally handicapped at providing enough rolling moment (main wing aileron is long gone) at extreme aoas. (see F-22's famous paddle walk), thus they are out of options. now unless flight test turns out that that's not critical or they are really going to get some good TVCs, fins are staying.*

which are not necessarily excruciatingly good RCS reflectors.... certainly the much smaller all moving smaller VT helped balanced out the total side RCS budget.*


over-all very nice job Mr. Yang Wei and Mr. Song. and all the hardworking folks at 611 and 132, hats off to you guys, merry christmas happy new year.*

Now let's see WS-15 is really what it touts itself to be.*

also bit of random thought.*

any one notice the big washout on the big anhedral wings?reminds one of concorde's wing?

couple that with the dihedral in the canards?*

lateral stability might not be a big factor in those choices.

==========


Also,*

they could make this really interesting by make a F/H-20.... think F/B-22.
it's already huge. lot's of room for gas and bombs.*
No need for absurdly high AOA demands, thus LEVCONs are ok. new compound curve wing, optimized for high speed cruise.*
all the system is paid for.*
heck even lighten the structure much up by decrease max G-load requirement from +9.5 to +6.
go tailless if one is venturous enough...


instant strategic bomber.

"How do you know ? Do you work at Shengdu ? "

No need to. See page 16 of this thread. They open sourced their own studies on this intake design! You can read the conclusions the Chinese came to in English. Their own conclusion is it suffers no penalty in the .6-1 mach range, but at speeds over mach 1 there is a penalty with this intake design. It becomes rather serious at or around mach 1.5. Like the Flanker, this is a design optimized for nose pointing in the transonic or low mach sphere.*

The T-50 is as much a MiG-31 replacement as it is a Su-27 replacement. It is optimized for high mach performance. In fact, in the transonic zone its probably inferior to the J-20 because canards at those speeds will do a lot for you.*

Typhoon, Rafale and Gripen are not serious mach 2+ performers. The T-50 is built to live at or above mach 2, lots of sources out there cite the mach 2.2 number -- including Russian state TV.

couple of points

the source you pointed to was from some Phds writing papers in Nanjing University of Aeronautics and Astronautics. good school, but hardly the final word.*
fyi, original design calls [note: I presume he meant for the J-20] for a caret intake. they didn't do dsi for fun of it.*

if T-50 is opitimized to live above M2 then why bother with the big surfaces. one big compound delta wing would surfice.*

btw, in these fighters, top mach # means very little by itself. push the engine out pass blade temp and you can up the mach. the point is how much drag you will get in turn and cruise and at what altitude.

see my reply in blue


I think they chose a safer and the most popular path - intakes at the side F-22/F-35 style, and narrowly situated engines, result - very bulky airframe. Raptor's problem is short legs, so they probably tried to find/create some space for fuel and made J-20 longer.*

I think they were juggling the choices between lifting body type aka T-50 and the canard/lex/delta combo they were trying to do. Mr. Song's original paper talked about this problem. basically the choice is that a flattened blended wing-fuselage can not realistically mount the canard up and above the main wing.*
One thing one does not do often is to get inside of the chief aerodynamicist's head on a particular project. what his reasonings are initially and see the final product. this might be an exception.*


I don't see such long and heavy aircraft to be in the same class as F-22 and T-50 in terms of maneuverability. Also it will need monster engines to SC, but even then DSI intakes will put its limits.

I think you may be surprised. you still hasn't see its actual weight class. human eyes are deceptive.*


YF-23 and T-50 designers were more original, they were able to create internal bays without bloating the whole design.

if I remember correctly (or not), original YF-23 had problems fitting in larger bays that AF wanted. I do not know whether they will be successful in that regard if they choose to kept the development going.”


as far as size goes. the key is engine.
all the information pointing to WS-15 as squarely a F-135 class engine.*
with all the T/W ratio to match.*

if I remember correctly, J-10's 1st prototype was with in 100 kg of its designed weight. the same team that does J-20 now has gone through now 2.5 programs (J-10, FC-1, J-10B), in less than 20 years. I would guess the probability that it would be overshoot its weights target would be kinda low.*

planeform area may look deceptively small. and its sides are broad single wedge, and with an top wing design. thus give one the impression of "heavy".”

“May be The reason some think it is "bloating the whole design" because they choose to use an upper wing mounted on top of fuselage. by contrast F-22/-35/T-50 all have mid mounted wing. also. notice the landing gear strut attachment location. should give some indication where they have their main load bearing structure laid out. This thing's structure reminds of X-32 actually...*

also, remember, doesn't matter how much lift one's fighter's body can generate. the lift-over-drag is still better on a pure wing. .
with its Canard-LEX-Delta combo this thing may have deceptively smaller on paper -wing loading.