Official Chengdu J-20 Discussion Thread

[Bonza]

I'm admittedly no expert when it comes to aircraft design, but I think it would be primarily a matter of design requirements. The SU-35BM for example does not include canards as standard, despite canards being relatively commonplace among advanced Flanker variants. Presumably this is because other features like thrust vectoring, flight computers and airframe materials mean canards are not necessary for attaining the required levels of performance. Sure, canards may offer some advantages of their own - but if the design already meets requirements, is it worth incurring a drag and RCS penalty for the sake of exceeding those requirements?

On the other hand an aircraft like the SU-33 probably gains a lot more from canards than the SU-35BM, as it is expected to operate from aircraft carriers and thus additional lift and control is highly desirable. But I don't know nearly enough about aerodynamics or aircraft design to say for sure, so I'm just speculating.

Retractable canards might work, but they and the required retracting mechanism would incur penalties to weight and internal space, both of which are at a premium on a modern combat aircraft, in addition to the drag and RCS penalties incurred when they are extended. So it's a question of whether the utility offered by such canards would be worth the drawbacks - personally I suspect it might be easier to meet performance requirements in another way. As I said though, this is just speculation, your mileage might vary.

 

[SURB]

The concept of retractable canards is not new (more than a decade old with existing patents). There are design issues eg when the canards are in the process of retracting, how does the plane fly? At the same time, it may not be easy to optimise an airframe to perform safely with and without the canards.

Also, what happens if the canards get stuck. How to house them etc. When the optimum time to utilise the canard etc. The use is possible but a lot of issues to consider and test.

Any additional surface increases RCS. Aircraft like the typhoonp may use software to calculate and control the surface to minimise RCS. Retracting it just to minimise RCS may not be beneficial when compared to the loss of flight control.

Well that's great to know if somebody was thinking on the same lines..Was this concept got tested anytime back in the past on any platform?(as you mentioned it's quite an old one).
For typhoon this concept of retractable canards doesn't seems practical.But for a heavy stealth bomber or fighter,it can still give some advantages.You can synchronize it with FBW control when the aircraft is flying steady there is no need to apply them.

But i totally agree with you as far as the above mentioned shortcommings are concerned.But that too demands testing and gradual improvement.

 

[weasel1962]

Re:

Well that's great to know if somebody was thinking on the same lines..Was this concept got tested anytime back in the past on any platform?(as you mentioned it's quite an old one).
For typhoon this concept of retractable canards doesn't seems practical.But for a heavy stealth bomber or fighter,it can still give some advantages.You can synchronize it with FBW control when the aircraft is flying steady there is no need to apply them.

But i totally agree with you as far as the above mentioned shortcommings are concerned.But that too demands testing and gradual improvement.

I'm not aware of any defense projects that incorporate the retractable canards. I would however highlight that concepts may take decades to be incorporated. An example is the stealth flying wing which ironically was a 2nd world war/50s discovery.

Others have highlighted that, in a similar vein, the F-14As had extendable glove vanes which are on the leading edges of the wing gloves. Doesn't appear on other variants of the F-14s though.

 

[Cailet]

But i totally agree with you as far as the above mentioned shortcommings are concerned.But that too demands testing and gradual improvement.

I suspect the real killer would actually be 'where does the the canard retract to?'. With space at a premium aboard your aircraft the canards would need some place to go that wasn't the radar/sensor package and wasn't the cockpit and I can't iamgine there's a great deal of space between them.

 

[Feanor]

I suspect the real killer would actually be 'where does the the canard retract to?'. With space at a premium aboard your aircraft the canards would need some place to go that wasn't the radar/sensor package and wasn't the cockpit and I can't iamgine there's a great deal of space between them.

Couldn't they fold rather then retract, and instead of going into the body, just fold along the body?

 

[SURB]

I suspect the real killer would actually be 'where does the the canard retract to?'. With space at a premium aboard your aircraft the canards would need some place to go that wasn't the radar/sensor package and wasn't the cockpit and I can't iamgine there's a great deal of space between them.

How about providing a dinning table to the pilot in the cockpit.The meal is over when you need the canards outside.

All depends upon their position on the platform.By discussing this idea here i meant bigger platforms like J-XX which can be easily modified to carry such accessories.

Couldn't they fold rather then retract, and instead of going into the body, just fold along the body?

That seems a bit difficult. Untill the surface is not flat to incorporate them.And more or less will be decided by the shape and the overall structure of A/C.Could have been experimented on F-117 i guess.

 

[gf0012-aust]

Any additional surface increases RCS. Aircraft like the typhoon may use software to calculate and control the surface to minimise RCS. Retracting it just to minimise RCS may not be beneficial when compared to the loss of flight control.

Any additional surface potentially can increase RCS. Aircraft like the typhoon may use software to calculate and control the surface to minimise RCS. Retracting it just to minimise RCS may not be beneficial when compared to the loss of flight control.

The canards are critical to flight perfornance for these aircraft. - removing them is just as likely to result in an RCS hit as the RCS is already factored in to include canards through various handling profiles...

FBW results in literally thousands of micro commands going to handling surfaces... (eg look at the F-16)

 

[Marc 1]

FBW results in literally thousands of micro commands going to handling surfaces... (eg look at the F-16)

My thoughts exactly - having seen in flight video of one of the aerodynamically unstable teen series fighters flying straight and level - and watching the control surfaces dancing about as though they had parkinsons disease, there is possibly no way they could be 'stowed' when not engaged in combat manouvres - the jet needs the control sufaces to feep themselves flying, because unlike a basic cessna that is natuarally stable, without the computers making these minute adjustments the aircraft will fall out of the sky.

 

[weasel1962]

Re:

My thoughts exactly - having seen in flight video of one of the aerodynamically unstable teen series fighters flying straight and level - and watching the control surfaces dancing about as though they had parkinsons disease, there is possibly no way they could be 'stowed' when not engaged in combat manouvres - the jet needs the control sufaces to feep themselves flying, because unlike a basic cessna that is natuarally stable, without the computers making these minute adjustments the aircraft will fall out of the sky.

The F-16 didn't exactly have canards so its not exactly a must have for any aero-dynamically unstable design. Could the F-16 actually benefit from having canards in some situations, actually? It could.

The complexity of FBW calculations is immense and requires a lot of computing power. However, if there's anything that has grown exponentially over the past decades, that is computing technology and massive processors.

It could merely be a timing issue before such calculations and technology becomes mature to be incorporated into actual designs. That's crystal balling though but not unrealistic to assume.

 

[Kilo 2-3]

The F-16 didn't exactly have canards so its not exactly a must have for any aero-dynamically unstable design. Could the F-16 actually benefit from having canards in some situations, actually? It could.

The complexity of FBW calculations is immense and requires a lot of computing power. However, if there's anything that has grown exponentially over the past decades, that is computing technology and massive processors.

It could merely be a timing issue before such calculations and technology becomes mature to be incorporated into actual designs. That's crystal balling though but not unrealistic to assume.

There were a couple of programs back in the mid-late '70s which tried fitting some additional control surfaces to F-16s. To the best of my knowledge the results looked fairly promising (the CCV/AFTI F-16s had better control authority and a wider range of maneuvers); but IIRC the additional control surfaces never made it onto any production F-16s.

• http://www.f-16.net/f-16_versions_article13.html
• http://www.f-16.net/f-16_versions_article15.html
• [2.0] F-16 Variants

Looks like the JASDF and Mitsubishi tried something similar with the third production T-2.

• http://www.airforceworld.com/attacker/gfx/f1/t2ccv_1.jpg
• http://www.airforceworld.com/attacker/gfx/f1/t2ccv_1.jpg

 

[gf0012-aust]

The F-16 didn't exactly have canards so its not exactly a must have for any aero-dynamically unstable design. Could the F-16 actually benefit from having canards in some situations, actually? It could.

The complexity of FBW calculations is immense and requires a lot of computing power. However, if there's anything that has grown exponentially over the past decades, that is computing technology and massive processors.

It could merely be a timing issue before such calculations and technology becomes mature to be incorporated into actual designs. That's crystal balling though but not unrealistic to assume.

I attended a briefing by a RAF exchange pilot about 18 months ago. He discussed the handling characteristics of the Typhoon and made it pretty clear that the canards, even though conjoined so no separate pitch management were critical to its handling (which he regarded as superb)

btw, the F-16 was trialled and muled with canards at one stage.

 

[dragonfire]

Assuming this picture supposedly of the J-XX program of China has not been discussed yet

- Would love to understand various inputs from the experts

 

[SURB]

Assuming this picture supposedly of the J-XX program of China has not been discussed yet

- Would love to understand various inputs from the experts

Well this picture is new to me.Looks like a combo of F-22 and F-35.
And no canards,plus looks smart if we compare it with the flankers and the previous airframe designs of the Chinese fifth generation existing on the internet.

Thanks for sharing.

 

[Scorpion82]

Photoshop. That's an image of the F-22 probably take at Marietta. The aircraft has been extracted and pasted over that image from an Chinese airbase. Honestly Chinese fakers suck like hell.

 

[Feanor]

It could be a PAK-FA photo. The aiframe is similar enough, and the paint-scheme matches the early PAK-FA prototype paint scheme.

 

[Blitzo]

It could be a PAK-FA photo. The aiframe is similar enough, and the paint-scheme matches the early PAK-FA prototype paint scheme.

Not PAK FA, T-50 has the all moving tails and doesn't have the side weapon bays (nor the single piece canopy, and it's rear end is way different, etc). It's obviously an F-22 PS...

Any J-XX (or J-20, as some people are starting to call the 4th gen fighter) will probably have canards. Just keep an eye out for stealthy fighters with canards. (The first two prototypes are reported to have completed assembly and test aircraft 2001 is undergoing taxi tests. We might get photos within a year, if we're lucky...)

 

[Cailet]

Blitzo, I assume I missed something in the thread but where is it confirmed that J-XX will have canards? I thought the discussion of canards in this thread related to J-10 (and similarly configured Euro aircraft) more than any future (and as-yet unseen) 5th-gen offering.

How about providing a dinning table to the pilot in the cockpit.The meal is over when you need the canards outside.

Yes but imagine what some spilled ketchup would do to your RCS, if that stuff dries on you're never gonna get it off

 

[gf0012-aust]

It could be a PAK-FA photo. The aiframe is similar enough,

thats a photshopped F-22. the rear quarter is not PAK-FA

these people need to get a life and stop faking stuff to make their military look stronger - its almost as bad as the photoshopped Ronald Reagan

 

[Blitzo]

Blitzo, I assume I missed something in the thread but where is it confirmed that J-XX will have canards? I thought the discussion of canards in this thread related to J-10 (and similarly configured Euro aircraft) more than any future (and as-yet unseen) 5th-gen offering.



Yes but imagine what some spilled ketchup would do to your RCS, if that stuff dries on you're never gonna get it off

Well I haven't gone through this entire thread, but I'm assuming nowhere is it confirmed that the 4th gen fighter will have canards -- no one's confirmed or denied the J-XX's existence, officially, nevermind its configuration.

But if you keep an ear out there are always a few rumours flying around that eventually turn out to be true. Here's a good, relatively site to keep you up to date on some of the PLAAF's pet fighters and projects:
Chinese Military Aviation | China Air Force (scroll to bottom to see entry on J-XX)

I'm quite sure that the J-20 will feature canards, some sort of DSI intake and LEX/LERX. I'd almost bet my left one on it. But we'll have to wait for pictures to emerge.

With chinese weapon systems you can usually only get a hint of what kind of future they have in mind by rumours, which I presume is why PLA related threads aren't as discussed on defencetalk very much -- there's simply not enough concrete evidence to convince people.

 

[My2Cents]

There were a couple of programs back in the mid-late '70s which tried fitting some additional control surfaces to F-16s. To the best of my knowledge the results looked fairly promising (the CCV/AFTI F-16s had better control authority and a wider range of maneuvers); but IIRC the additional control surfaces never made it onto any production F-16s.
[/LIST]

The CCV version fo the F-16 was abandoned because it freaked out the pilots. Simply put, many of the new maneuvers felt very much like the plane was going out of control, and it would be unsafe to train to accept them.

They ought to bring the idea back for UAVs, it would give them maneuverability impossible to match with manned aircraft.