J-35 carrier fighter (PLAN) thread

Gloire_bb

Colonel
Registered Member
1: The J35 is designed around nearly 40 years after the Flanker and the computational capacity has increased tremendously, allowing designers to make aerodynamic gains by more thoroughly optimizing the airframe. I would suspect that this alone offsets the Cd penalty to some extent. We also have to consider that modern fighters usually carry a few A2A missiles even in strike missions, and J35 carries these internally with no additional compromises to its aerodynamic shape. Overall I do not expect the drag coefficient increase to be overly worrying.
Broad direction of development - in most countries, but China is one of them, - is ironically the opposite.
Aka, less and less fine/risky aerodynamics, more and more gains via investment into engine power/effeciency.

Fine refinements do help, but overall J-35 is still a rather heavy(deck) medium aircraft of a rather conservative layout, with substantial parasitic internal volume (weapon bays and serpentine ducts), which take as much volume as a 3rd engine. Furthermore, it really appears that major design intent for both airframe and engines was achieving supercruise(don't know how applicable it is to naval J-35*) rather than range.
Flanker, on the other hand, is effectively a kite with 3 nacelles.

*Сan WS-21 be higher bypass when compared to WS-19?
2: Internal fuel. According to yankeesama the Air Force J35A has at least 7t internal fuel (source is one of the podcasts either this or last year, I'll have to look it up). If we assume the naval J35 has similar capacity then it should be plenty enough for any operations within reason. Remember that fuel quantity is not the only determining factor of range, you also need to consider aircraft weight (J35 would be lighter), as well as tsfc, and L/D, both of which I would assume J35 (having a newer engine design and having undergone better aerodynamic optimization) is at least comparable to the J15T.
This, btw, isn't all that high as for an aircraft without access to external fuel; or 3.5t per engine.
F-35A carries 8.2t with (likely) substantially lower sfc(F-35C almost 9). Su-33(J-15) does 9.5t, Su-35(proxy for an advanced flanker) 11.5t.

International hotcake medium fighter (rafale) - 9.5t fuel (internal+external); with tanks, but also with very clean/refined base airframe. Likely will be even more soon enough(they promised CFTs).
 
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Schwerter_

Junior Member
Registered Member
Broad direction of development - in most countries, but China is one of them, - is ironically the opposite.
Aka, less and less fine/risky aerodynamics, more and more gains via investment into engine power/efficiency.
Fine refinements do help, but overall J-35 is still a rather heavy(deck) medium aircraft of a rather conservative layout, with substantial parasitic internal volume (weapon bays and serpentine ducts), which take as much volume as a 3rd engine. Furthermore, it really appears that major design intent for both airframe and engines was achieving supercruise(don't know how applicable it is to naval J-35*) rather than range.
Flanker, on the other hand, is effectively a kite with 3 nacelles.

*making an interesting theory; can WS-21 be higher bypass when compared to WS-19?

This, btw, isn't all that high as for an aircraft without access to external fuel; or 3.5t per engine.
F-35A carries 8.2t with (likely) substantially lower sfc(F-35C almost 9). Su-33(J-15) does 9.5t, Su-35(proxy for an advanced flanker) 11.5t.
I would beg to differ on how much advances in CFD and simulations contribute to aircraft performance, better/more optimized aerodynamics doesn’t equal more outlandish and radical designs. Small, hardly visible changes to the aerodynamics — a slight modification to leading edge, tweaking the spread of wing twist, changing the contours of the fuselage at select places, etc.— add up to very noticeable gains in efficiency. All of this is impossible (or at least extremely time-consuming and hard) a few decades earlier, when CAD was in its primitive stages, high fidelity CFD for complex shapes is conceptual at best, and the most reliable way to figure out how a design works is to build one and fuck around to find out. Aircraft design has come a long way.

I also feel like I have to correct the mindset that “aerodynamic performance is judge-able by eye”. Not meant as an attack to anyone in any way, it’s just that doing so is highly unreliable at best and can lead to people being very wrong very confidently at worst, not to mention the definition of “good aerodynamics” and “bad aerodynamics” which is a whole other can of worms. A modern design with a weapons bay, VLO features and a “boxy” fuselage doesn’t necessarily have “worse” aerodynamics than a 40-year-old design that looks streamline. Take the flanker as an example: yes it’s well-designed but the “kite with 3 nacelles” isn’t all good: it has to invest extra weight to bulk up its force-bearing frames compared to a box-ish fuselage, the relatively large surface-to-volume ratio creates higher parasitic drag, to name but a few issues. Ultimately aircraft design is about trade off and it’s generally bad practice to intuitively judge such things.

The assumption that having a weapons bay is detrimental to the aerodynamic performance is also not entirely correct. Yes it’s extra weight and volume, but it’s only really a pure detriment when nothing is carried internally, which is not usually how people use fighter jets. When you need to carry, say 4 ~200kg missiles, the drag benefit from not having to carry unoptimized bodies externally adds up really quick, and may actually even out the penalties or even provide an advantage in certain scenarios. Remember that drag isn’t additive, a fighter jet carrying a missile externally has more drag than that of the fighter and that of the missile simply added together. There’s vortices, changed flow fields & pressure distributions, shockwaves forming and reflecting between stuff, all of which is basically a very big middle finger to the design team.

Range-wise the Guancha trio also touched on this on many occasions with the general concerns us being that the J35/J35A has surprisingly good range, partly due to how stealth fighters work (no/little external storage, large internal fuel, less reliance low level flying to avoid detection, etc.) As I said fuel quantity is only one of several factors determining range, a large fuel quantity doesn’t necessarily mean proportionally more range and vice versa.

also I need to correct myself: having located the podcast in question, the internal fuel is apparently 8.X (hinted at at least 8.1 and possibly higher ) ton for the Air Force J35A (no mention of naval J35 but it should at the very least not be significantly smaller). Apologies for not looking this up for the original post.
Time stamp is around 18:00 for this link
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Schwerter_

Junior Member
Registered Member
Broad direction of development - in most countries, but China is one of them, - is ironically the opposite.
Aka, less and less fine/risky aerodynamics, more and more gains via investment into engine power/effeciency.

Fine refinements do help, but overall J-35 is still a rather heavy(deck) medium aircraft of a rather conservative layout, with substantial parasitic internal volume (weapon bays and serpentine ducts), which take as much volume as a 3rd engine. Furthermore, it really appears that major design intent for both airframe and engines was achieving supercruise(don't know how applicable it is to naval J-35*) rather than range.
Flanker, on the other hand, is effectively a kite with 3 nacelles.

*Сan WS-21 be higher bypass when compared to WS-19?

This, btw, isn't all that high as for an aircraft without access to external fuel; or 3.5t per engine.
F-35A carries 8.2t with (likely) substantially lower sfc(F-35C almost 9). Su-33(J-15) does 9.5t, Su-35(proxy for an advanced flanker) 11.5t.

International hotcake medium fighter (rafale) - 9.5t fuel (internal+external); with tanks, but also with very clean/refined base airframe. Likely will be even more soon enough(they promised CFTs).
Apologies for only just seeing the last paragraph about Rafael, allow me to present the info in another light.

9.5t fuel: around 4.7t internal, the rest is carried in drop tanks which have very low efficiency (iirc on average around 30% of the fuel carried in drop tanks is used to make up for its aerodynamic impact) and atrocious drag.

very clean/refined base airframe: true but again there’s a 20 year gap between available tech at design phase, the J35 would have significantly better simulation and computer-aided design optimization done to it, not to mention better structural design that reduces weight. Also there’s next to no point comparing the aerodynamic performance of something entirely relying on external carriage to something that can carry a substantial part of its arsenal internally: You’ll be surprised how fast flight performance takes a nosedive due to excess drag when you slap a few fuel tanks and some missiles onto an otherwise perfectly fine aircraft.

CFT: AKA slightly better external tanks, still not as good as designing the fuel into the fuselage in the first place if that’s the amount you actually need. It’s essentially making up for designing the aircraft with too little fuel in the first place.
 
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