China Unveils Yet Another Stealth Jet: Shenyang J-31

[DeltaV]

Just remember that looking stealth and being stealth are two different things.

I'm sure they have radar ranges too. If they hacked the F-35 dimensions then they can do F-35 geometric reflectivity. Surface composition is another matter.

Also the Chinese still don't make high performance engines, it remains beyond them (albiet for now).

Emphasis on "for now".

The other most important thing that makes an aircraft Gen 5, is not how it looks as much as whats in it for avionics, sensors, comms, weapons, countermeasures, etc.

Since most electronics are now made in China... But I get your point, it's the systems integration. That they could fly a twin-engine F-35 knock-off this quickly, however, shows that they are getting their **** together in that department.

[ladajo]

Shape is one thing, materials is completely another. The previous design had some obvious shape flaws, which I thought interesting. I still think they are way behind the curve on materials that is stealthy and performs.

As for flying a "look-alike", I do not think it is that impressive. Modelers and hollywood do it all the time. What are the preformance envelopes and platform capabilities, that is the real question. I do not think they are even close to being there yet. Especially when one starts talking about integrated linked sensor systems.

I really do think there is a lot of misinformed hype when it comes to actual Chinese capabilities. But, to be fair, you don't really know until you actually fight. And in that vein, to date, the US has proven capabilities over and over, while the Chinese have not really proven anything for a long time. Testing is one thing, actual combat is another.

[DeltaV]

We can only surmise. Time will tell.

J-31 top, F-35 bottom:

[krenshala]

The J-31 looks more like a knockoff of the F-22 than the F-35 to me. Both are twin engine, the intake looks pretty similar, not to mention the vertical stabilizers. There are definite similarities to the F-35, mainly wings, however, so I guess it could be a knockoff of both aircraft.

[GIThruster]

Its a carrier plane, so might best be called an F-35 killer.

[ladajo]

Why?

[GIThruster]

The F-35 was conceived of as a low-cost multi-purpose platform. It thus has only one engine. All disappointments aside that it is no longer anything like low cost and should have been cancelled long ago, it cannot compete with modern two engine fighters. It's like pretending an F-16 would be a decent match against an F- 14, F-15 or F-18. The F-16 was a good fighter for what you paid. The F-35 was supposed to be the next gen stealth enabled equivalent of an F-16 but with STOVL thrown in. (Fact is, it was originally supposed to be VTOL and it's not that anymore either.)

Basically, the program sucks. It's costing a fortune--more than $400B now and all the tactical evaluations show it getting its ass shot off by anything new. There isn't much point in building a fighter that can only succeed against 30 year old fighters and weapons systems.

IMHO, the only sensible solution is to end the program and throw everything into the next gen UCAV's like the X-47B and Cormorant. At least when they get shot down no one is lost and they still hold out the possibility of being cheap.

Now that we no longer need to worry about losing pilots in combat, we need to be thinking in terms of having twice as many cheap UCAVs rather than nut busting over small performance improvements. Twice as many guns in the sky is always going to win a fight and without pilots to lose, combat is turning into simple economics.

[ladajo]

I see two problems with you argument.

1. Engine power only brings run away speed and possibly climb rate. A low mass single engine can be a very effective performer. This really only matters in gun fights. Most fights today are missile. And perferably missile at a distance.

2. You over look the most important thing that F-35 brings to the fight. That is capability. It is bluntly the most capable flying killing machine to date. The integrated sensors, flight and weapson control is unmatched by anything else in the air. Its ability to evade/limit detection and locks is also unmatched. It is a even big step forward in capability from the F-22. F-22 is on a long roll upgrade plan to catch it up with F-35 systems.

3. The aircraft is VTOL btw. It has not "lost" this ability. Rolling takeoff is used to save gas in the amphibious version. It can hover or take off just fine. You would just want to gas it for full legs afterwards, just like we do with pretty much any combat loaded aircraft given the chance.

I think your primary argument is focused on 2 engines or 1. I would point out to you from a maritime aspect the A-4 Skyhawk was a very capable and long flown airframe with a solid combat record. Many folks still flew it long after the US stopped.

[GIThruster]

Well, it's not my argument. It's the argument made by the Air Power Australia and Rand Corporation analysis. The "handling" of those simulations since has shut up complaints but the complaints certainly seemed valid to me. Fact is, the F35 does not have the thrust/weight of two engine designs. It cannot carry the same weapons load. It is more observable and lower performance than Russian and Chinese fighters.

The observation you're making about what the next generation of sensors and avionics will be capable of can be applied to almost any aircraft. Almost all those benefits could be applied to existing F-18's for example. It's true the US has always enjoyed a serious advantage when it comes to better avionics. It's not true those advantages are unique in any way to the F35.

I suggest look at the wiki site and especially the Air Power/Rand studies:

http://www.ausairpower.net/APA-2009-01.html

The contention is, that single engine thrust/weight cannot compete with double engine thrust/weight, and this is something we've known for decades. There are lots of reasons that F-16 was never made a front line fighter, and these all relate to the reduced thrust/weight of single engine fighters.

And just saying, you need to do a hard analysis of how the thing will be used. When you have the B variant with the fan, you lose 1/3 the fuel. When you add the external weapons pods or carry missiles, bombs or tanks on the external hardpoints you lose your stealth, speed and range. It's a single airframe designed to be configured 3 different ways, and then loaded 30 different ways, so generalizations about it are hard to make. It is not hard to show though, that the greatly reduced thrust/weight is a serious concern when up against other 5th generation aircraft.

Just in summary, this thing was designed to be cheap and it is not. The stated goals of the program were that development costs aside, the procurement costs would be the same as our current front line fighters, the F-18. They're not. the current projection is the plane will cost more than twice as much. One needs almost no analysis past that. In planning for cheap, we lost the second engine and all that entails, and now we find the plane is not going to be cheap.

Spend time with the wiki piece too. The sheer numbers of problems with the plane at this late date are shocking and alarming. 20 years and the helmet mounted display does not work. How FUBAR is that?

[DeltaV]

The J-31 looks more like a knockoff of the F-22 than the F-35 to me. Both are twin engine, the intake looks pretty similar, not to mention the vertical stabilizers. There are definite similarities to the F-35, mainly wings, however, so I guess it could be a knockoff of both aircraft.

To me it looks like J-31's intakes are virtual clones of the F-35's diverterless supersonic inlets:






J-20 also uses DSI's, unlike F-22 (it's hard to see the inlet bumps in the J-20/31 photos):






The vertical stabilizer cant angles are very similar for all four.

J-31 has a rear-hinged canopy, unlike F-35 with its B version STOVL duct constraint.

An advantage of two engines is redundancy with failures or battle damage. A disadvantage is weight and double the failure probability.

Add 360 thrust vectoring to dual engines and max roll rate improves, not just pitch and yaw. A high roll rate is critical for turning the lift vector and keeping positive g's on the pilot during a dogfight or terrain following.

The Russians like a wide engine spacing to maximize vectored thrust contributions to roll rate, and for packaging reasons (T-50):

[ladajo]

I would completely beg to differ that you can install the kit for an F-35 into a legacy airframe. You have no idea what you are talking about here.
The kit is what makes it 5th gen. The airframe was designed to mount the kit, the kit was not designed to mount the airframe.

There is no comparison package in the air or near to being in the air. Nor will there be for a while.

I do agree that there are advantages (and disadvantages) to dual engine. I would also agree that there are strong arguments to twin engine, and normally I tend to lean this way. But interestingly, there are some good points to single engine. One of which I will raise is observability.

F-16 is a strike aircraft. It is also a viable air-air platform. Folks still use it as such. F-15s brought multiple sparrow, and then AMRAAM to the fight, and that set them apart (then). But in real terms the most value we got out the series was Strike Eagle. It is a medium bomber in historical terms. Funny thing though, F-16 can also lift a serious air to ground payload.

F-14 was a terrible air-air platform. It was too darn big. It most effective use was to launch the wing loaded with 4 Pheonix each , and knock down the 300 inbound flying russian schoolbus anti-ship missiles.

F-18 comes in two flavors. Which in reality are two completely different aircraft that only share the "F-18" designator. The C/D legacy birds are not long for the world, and the remaining A birds are already about extinct exsiting only a RDTE or FRS birds. E/F has nothing to do with A or C/D frames. And the G is a F that costs more. Thinking that you could retrofit these airframes with F-35 kit is just plain silly.

You MIGHT be able to argue that you could retro some of F-35 into F-22 but even that is a stretch.
You really are out of your depth on this one. You really do not know what is under the hood, and for good reason.

[GIThruster]

Sorry, not seeing any evidence you have any idea what you're talking about.

I think instead of offering lame excuses for a system that is obviously broken, you'd do better to read the Rand analysis.

F35 only made sense when everyone was assured it would be cheap. It is no longer cheap and it a poor investment. That's why both the Aussies and the Europeans are thinking about backing out. F-47b still holds out the possibility of being affordable. In the meantime, the Australian recommendation is to buy F22's and pass on the F35's for all the reasons outlined in the Rand study. There is no evidence the F35 will be able to compete effectively with the Russian and Chinese planes, because it only has one engine.

[ladajo]

Well, I guess that you will have to take it on faith that I know what is under the hood. I am also sure that you do not.

As for UCAV, UCASS and others, I am in full agreement. I think unmanned is the way to go for many reasons. Especially in the interim unmanned air to ground further development from where we are now. Especially in combined manned/unmanned mission sets. That is easy gain, the other bit which is a tad harder, but achievable in the short term is the navy focus on unmanned air to air. Mix that as a composite mission set as well in the interim and we've got some serious advantage in many fights.

Back to F-35, I personally would love to see a follow on two engine airframe using the same kit concepts. But that is just me, and I am sure it would not be cheap.

In an integrated fight environment, F-35 is serious leverage.
Engines do not make a airframe 5th Gen.

[GIThruster]

I think all of the lessons learned with the F35 will be useful. It's engine is the highest performance engine of its type in the world. It's the first craft to use carbon nanotube composites. There are all sorts of things to be gained from the program. It's just that the plane itself is not amongst them.

If the Marines really NEED a VTOL, it's best to optimize from the start and stop pretending the A, B and C are all the same plane. They're not. The new stealth coverage material is supposedly better and cheaper. We can use it on any design.

I would say though, that a careful study needs to be done to see just how much internal bay storage is necessary for an ideal multi-role fighter. The F35 doesn't have much bay storage and there's no point hauling around all your stealth material, and compromising aerodynamics for the sake of stealth, if you're going to throw all that away by hanging guns, rockets, bombs and tanks all over the airframe.

Probably the idea solution is a 2 engine plane with much larger internal bays, longer range and supercruise. Basically, an improvement over the F22, that can land on a carrier, doesn't need a pilot and costs far less. That's a tough nut to crack and F35 isn't even close.

[ladajo]

Yes getting to a two engine "full size" unmanned airframe is a leap to some degree. But I am not sure sure it is as far off as you are thinking.

The new stealth coverage material is supposedly better and cheaper. We can use it on any design.

I disagree with the idea the F-35 stealthing is "exportable".
The system is more than the paint job.

The VTOL package requirement is driven by the Amphibs themselves. As for the groundup design of a marine dedicated bird, I just don't see the political will in the Pentagon to go the route. It has been tried, and never gets far. The fixed wing package going forward for ARG ops is sufficiently met with F-35 and MV-22. That combo is giving our force capability some legs it never had before. That capability alone is lightyears ahead of any near competitor. And it worries them greatly. They now have to factor protective factors into the deep battle space that they had not to worry about before, and it is an exponential cost for them. The stupid ones will never see it coming.

Now if we can catch up with kenetic fires to have the reach the boots do, ohh my.