I am not an expert on this field but I have serious doubts you can squeeze something as complex as aerodynamics into two simple numbers, T/W and T/D, completely disregarding things like pitch authority due to canards / tailerons, FBW settings, inherent instability etc.

BTW, despite of all the T/W talks, most jocks consider the F-16C a better close-in performer than F-15C, let alone F-15E. How that this fit into your calculations?

True and true. Since you mentioned; take F-15C, PW-200 engined; T/W = 1.31, 3741 N/m2 T/A(wing area).

This tells us F-15C’s wings are greater source of drag than F-16C. This CAN translate to less sustained rates on F-15(or not). With 19% more T/W, but 26% T/D, it would all come to other details like Cd, and efficiency in lift generation (L/D). In case of F-15/16, F-15 uses thinner airfoil, at the root (and thus overall), has less Clmax, but also less Cd. This design choice allows similar acceleration at the cost of worse maneuverability.

Assuming comparable Cd with Blk50 F-16, J-10 has 9% less thrust and 48% less drag. If you think advancements in aerodynamics will overcome this, I disagree, it wont. Like I’ve said, J-10 has to be 61% more efficient in lift generation just to match F-16.

BTW; If you ask my opinion GE-129 powered F-15E can easily run circles around F-15C or any F-16.

I completely understand.. What I don’t understand is why you expect Chinese to do so, anyway…

I don’t. As a domestic product its good enough for Chinese. But for export, there is F-16 and MiG-29 on the table; both proven and better, and then there is J-10, which is neither. Excluding many other options of course.

I know. The -132 is fully qualified for F-16C/D and F-15E, yet no one seems to want it. Could be price tag?

Could be. There can be also another reasons. If i were to speak for Turkey; Turkey already produces/assembles GE-129/129B engines locally, and Turkey operates a sizeable fleet with -129 (163 aircraft IIRC). 30 additional F-16’s were mostly due to delays in JSF production, so parts commonality within fleet and manufacturing concerns may have taken priority above individual aircraft performance. I believe similar concerns apply to all countries who had F-16 before their recent orders.

As for F-15E, who really needs more power than GE-129 anyway? Price tag could also play part in this.

Based purely on thrust to weight, an J-10A (9,700 kg empty) with Al-31FN (79.5 kN dry and 125.0 kN wet) falls between Block 42 (8,300kg empty, PW-220, 64.9 kN dry, 105.7 kN wet) and Block 52 Viper (8,300 kg empty, PW-229, 79 kN dry, 129.7 kN wet). Which is not bad, at all. At the same time, I cannot comment on how the J-10’s aerodynamics is more advanced than the one of an F-16.

The Al-31FN differs from the Al-31F by having the gearbox and accessories placed on the bottom instead on top. Generally, I think that mods incorporated in the FM2 version could be used to upgrade the FN, as well, although I haven’t heard about such version being in the pipeline. 117S is a no-go as it is based on a different engine and differs in inlet diameter.

On purely technical comparison you are right. But F-16 is -right now- offered with GE-132. All F-16IN, F-16V, F-16BR, KF-16 had GE-132. And right now, J-10 is -until now- offered with AL-31FN. On theory, latter part is also correct, but it didn’t happen in real life and “engine” is still an important downside of J-10.

What export version? There is no such Pakistan specific variant since it never went beyond talks.

Talks or not, no one else has interested in J-10.

I highly doubt price is that much different

That was his point actually. If MiG-35 even closes Su-35’s price tag, why would anyone buy MiG-35? I understand your love towards MiG-29/35, but there is really nothing MiG-35 offers above Su-35. It needs to be way cheaper than Su-35 to stay attractive in export market.

That chart is wildly inaccurate, and produced before schematics of the T-50 from patents were released, or satellite photos of the J-20 were examined. The J-20 is nowhere near that large, since its length is revealed to be something like 20.5 meters long. Also, the T-50’s fuselage is more voluminous than the diagram suggests. Here’s an accurate frontal view of both the T-50 and F-22.

Sorry for a delayed answer. Ok, since you have posted the schematic from patent itself, I’ve merged it with Su-27 schematic from SK manual. Its as official/valid as it gets:

[ATTACH=CONFIG]236620[/ATTACH]

Matching them at wings, PAK-FA’s engines protrude slightly at top, its fuselage is fatter but wings are thinner, Su-27’s nacelles and vertical fins/stabilizers occupy noticibly greater space than PAK-FA’s.

EDIT: Its also interesting to see T-50’s inlet area is curiously larger than Su-27s.

To be completely honest, average people are capable to evaluate basic aerodynamics using eyeball Mk1 much better than they are able to evaluate RCS, for example. People are constantly confronted with basic aerodynamic principles for most of their lifetime while watching aircraft, Formula 1, sports cars or building paper planes. Don’t want to say that aeroduynamics is self-explanatory but on the other hand, it hardly requires a degree in aerodynamics to decide which car is draggier – a Ford Fiesta or a Lambo Hurracan.

My 0.02 only..

And that is why mk1 eyeball inspection is still utterly unreliable. An interesting fact: Formula 1 cars have higher drag coefficient than a Ford Fiesta, or a Lincoln Navigator or any road going vehicle, including trucks trailers and SUVs. Shocking to the uneducated but perfectly reasonable due to their design priorities; A truck requires fuel economy to be competitive, so lowering the Cd is highest priority. A formula 1 car prioritizes handling, so big/angled spoilers and front lips produce huge downforce, at the cost of Cd. Same reasoning applies to sports cars vs MPVs that Ford C-Max has a drag coef of 0,29 but a Ferrari F430 F1 has 0,34.

Just so we are clear. You think there is sufficient -empty- internal space in a Su-35 that the PAK FA could incorporate its four internal weapons bays, plus its additional avionics, all without increasing its volume over that of the Su-35?

Why don’t you point out for us the wasted space you would reclaim:

Well, reality is not exactly something to be pointed out from a cutaway. If you are asking about a theroatical discussion;

1-the huge equipment bay behind the cockpit has similar dimensions to No1 tank of Su-27, which holds 4050l of fuel. Such equipment bay is absent on F-16A (sharing similar nose shaping) and F-16 holds a 4060L fuselage tank and ammunition drum in its place. Instead, F-16 design distributes all these equipment at the sides of the cockpit and inside the LERX, which are -mostly- unoccupied in Su-27; Technically, following F-16’s design solution with smaller modern avoinics alone should give 4000+L additional internal volume.

2- MLG area of Su-27 does not closely follow tire contours, but merely surrounded by 4 titanium bulkheads. If they were designed with use of composites in mind, these areas could be converted to fuel tanks, adding 200+L fuel. In fact there are few more areas I alone can name for gaining few hundred L of internal volume.

3- Vertical/horizontal stabilizers can be made hollow to accomodate at least 800L more fuel.

You have to understand many things changed in 40 years; #1 was not possible in 70’s because Soviet avonics were simply too large. #2 was not possible without extensive welding as press shaping or casting would have degraded material qualities. #3 was not necessary as costs of doing such outweighted the gains.

In comparison, PAK-FA’s internal bays roughly occupy 6000L of volume. Even if we assume T-50 has same fuel capacity of Su-35 (11500 kg) it also shortens stabilizers, eliminates fins, shrinks elevators by 60-70%. Air inlets are shorter, overall length is shorter, and all the weight/volume gained in these is used on the fuselage, which adds up to the *usable* volume inside. However speaking of overall dimensions, PAK-FA is simply small, and I still believe its airframe occuppies less volume (in total) than Su-27.

Mk1 eyeball; Su-27 is considerably longer, wider, and higher. Su-27’s frontal and side area is considerably larger and its top area is slightly larger. No one can be 100% certain, but all these translates to greater volume to me.

The F-22 on the other hand, has a huge bended air-duct placed inside the airframe, which in it self is heavy and take up a lot or internal volume, which otherwise could be used for.. her it comes; Internal Fuel!

And then we have the Int W-bays.
Again its the same deal here as i explained above. The main Int W-bays on the Pak-Fa are slung underneath the airframe, at the very least a huge portion of it is!

Not only that. Pushing internal weapon bay and inlets further above the inside of the fuselage, makes it increasingly difficult to design a structure to withstand the high G loads, and F-22’s design leaves little vertical room for structure design.

For equal yield stress, Bending moment is proportional to moment of inertia. For bulkheads, it can be assumed as square, with B having cross sectional thickness, and H height, its I = B*H^3/12. This means If you reduce height H by 20%, you need to double the width to maintain same strength. Doing this, increases weight (proportional to B*H) by 1.6 times. In secondary effect, fuselage’s load bearing structure has to carry its own weight too, so lighter bulkheads decrease the required bending moment, further lightening it up. By mk1 eyeball analysis, T-50’s design allows entire height of the fuselage (at least at longeron cross sections) to be used for load bearing, with seperation between internal bays being the most critical part of the design.

You can’t optimize an engine for everything. Variable geometry inlets can help, but they don’t make much of a difference below M2.0, and so aren’t likely to be holding the F-22 back any with its supercruise speed of ~M1.8.

Variable geometry inlets start making difference from M0.00 to top speed. If you are comparing a fixed inlet solely optimized for subsonic flow and a variable inlet, then variable inlet starts making difference above M0,85.

If you want high dry thrust at high speed, you want a relatively low bypass engine. (which the F119 is) The catch is that this is not at all fuel efficient. If the PAK FA’s engines are capable of producing similar or greater (and it would have to be a great deal greater) dry thrust in supercruise conditions then they are going to be inefficient engines for cruise. So which is it? Are they more efficient at cruise, or offer greater supercruise performance? Short of a variable bypass engine they can’t offer both.

Bypass ratio and engine performance is not related to speed but altitude(pressure). See inlet, diffuser, nozzle and con-di nozzle. IF T-50’s inlets have just 10% better pressure recovery, it can easily translate to higher thrust. IMHO it would be stupid to think variable inlets has less than 10% improvement in pressure recovery, if they have gone so much effort putting it onto T-50.

With 2 fuel tanks F-22, reaches 2960 km. T-50 has certainly lower drag (clean aircraft, excluding airframe comparison); possibly higher L/D, less weight (reducing induced drag); I don’t see why it shouldn’t reach 3500 km with its internal fuel.

If you like to believe the F-22’s designers were just a bunch of idiots, how do you explain the obvious incompetence of the Su-35’s designers? How could they have screwed up so badly that only 2 years after the first flight of the final version of their new fighter that the PAK FA would fly… with all the same features and more, plus a bunch of LO features and internal bays… and all while weighing less and outperforming their new fighter in every way?

TBH, I’ve always found claims about Su-35 being an all new design complete BS. Obviously it didn’t started as clean sheet design. Its still designed within the boundaries of the original Su-27 design. In essence, Su-35 is just a revised Su-27. PAK-FA on the other hand is a true clean sheet design. Its smaller in dimensions, and I don’t think T-50 has grater total internal volume than Su-35. It simply uses available volume better. No suprise it weights less than Su-35.