I think most people are just reacting to the idea that canard configuration is an inherently less competent choice for signals management compared to other compromises being made on other platforms. When people see a claim saying "canards hurt RCS" for example they see it as code for "plane x is worse than plane y". Personally I think there is some validity to that interpretation of the language, and an abuse of technical understanding on any side of the discussion. At the end of the day everything is being sifted through a comparative lens.
Shenyang FC-31 / J-31 Fighter Demonstrator
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Agreed. And my agreement to your statement is based purely on my extensive reading (not as much thinking though, mind you) on the various Chinese forums since around 2006...
P.S. Not taking ourselves and our opinions too seriously is one of the simple wisdoms I've gained these years...
That definitely would be the wise appraoch... not only toward the Chinese military talk shows but to all such shows and such articles.
Vini_Vidi_Vici
Junior Member
To be completely honest, most people in this thread are biased to some degrees, more or less.
To be objective, at least trying to be, canards do affect the RCS, but depending on which angle it's being scanned by the radar. When scanned by an enemy plane flying straight at it, it makes no difference, since there is only a thin strip along the x,y plane. (assuing the horizontal and vertical plane of the radar to be x,y and distance between air-plane and radar to be z) The canard makes no difference, since the rear/main wing is the widest and will be the main factor in the RCS.
However, when being scanned by a land based radar, it makes a huge difference. Even when the plane is really far away, forming only a 10-20 degree angle relative to the radar, the air-plane is still "tilted" relative to the radar, thus increasing the surface area on the x,y plane, making it more visible. The closer the distance, the greater the effect. Hence canards do increase RCS in this situation.
Look when filmed from the ground, even when the plane is flying straight, it still appears to be tilted. This increases the surface area exposed to radar waves.
The best way to think about it is thinking about a stick/baseball bat. When someone points a stick directly at you at eye-level, you won't even be able to determine the length of it, because you can only see the tip. When it's pointing towards the sky, then you can see the whole stick.
The same idea applies to airplanes. Sure, stealth jets can reduce RCS even when being scanned from underneath, but the fundamental problem is that they start from a large flat surface. The canard makes it worse. Comparing F22 to J20, from a purely technical point of view, not saying which is better. Hypothetically speaking, say the radar scans the jets directly from underneath, say there's only x,y plane, no third dimension. The canards on the J-20 adds to the total surface area to the plane. Say the total surface area of J20 is 110-120 and F22 is 100. Doesn't matter how hard the engineers try to reduce RCS, J20 can still only achieve to being close to F22's level (very hard to surpass it), because it starts with a very large area. It's like making a fat man compete with a 170 pounder to diet to reach 150 pounds, obviously the skinny one will win. He doesn't have to lose that much in the first place.
Another thing I have noticed members have being claiming is that canards make TVC useless. This is actually not true. In Dr Song's papers, he actually mentioned specifically on this. He said TVC combined with canards is greater than 1+1. When used together, they multiply in effectiveness, making the plane more agile than with individual features.
To be objective, at least trying to be, canards do affect the RCS, but depending on which angle it's being scanned by the radar. When scanned by an enemy plane flying straight at it, it makes no difference, since there is only a thin strip along the x,y plane. (assuing the horizontal and vertical plane of the radar to be x,y and distance between air-plane and radar to be z) The canard makes no difference, since the rear/main wing is the widest and will be the main factor in the RCS.
However, when being scanned by a land based radar, it makes a huge difference. Even when the plane is really far away, forming only a 10-20 degree angle relative to the radar, the air-plane is still "tilted" relative to the radar, thus increasing the surface area on the x,y plane, making it more visible. The closer the distance, the greater the effect. Hence canards do increase RCS in this situation.
Look when filmed from the ground, even when the plane is flying straight, it still appears to be tilted. This increases the surface area exposed to radar waves.
The best way to think about it is thinking about a stick/baseball bat. When someone points a stick directly at you at eye-level, you won't even be able to determine the length of it, because you can only see the tip. When it's pointing towards the sky, then you can see the whole stick.
The same idea applies to airplanes. Sure, stealth jets can reduce RCS even when being scanned from underneath, but the fundamental problem is that they start from a large flat surface. The canard makes it worse. Comparing F22 to J20, from a purely technical point of view, not saying which is better. Hypothetically speaking, say the radar scans the jets directly from underneath, say there's only x,y plane, no third dimension. The canards on the J-20 adds to the total surface area to the plane. Say the total surface area of J20 is 110-120 and F22 is 100. Doesn't matter how hard the engineers try to reduce RCS, J20 can still only achieve to being close to F22's level (very hard to surpass it), because it starts with a very large area. It's like making a fat man compete with a 170 pounder to diet to reach 150 pounds, obviously the skinny one will win. He doesn't have to lose that much in the first place.
Another thing I have noticed members have being claiming is that canards make TVC useless. This is actually not true. In Dr Song's papers, he actually mentioned specifically on this. He said TVC combined with canards is greater than 1+1. When used together, they multiply in effectiveness, making the plane more agile than with individual features.
Vini_Vidi_Vici
Junior Member
Right now China doesn't have TVC in active service, so canards are essential in making jets agile, especially in something as big and heavy as the J-20.
I'm sure many Chinese members will say that TVC is useless when canards are installed. To those claims, I suggest go dig up some research papers first, then think about what to say.
I'm sure many Chinese members will say that TVC is useless when canards are installed. To those claims, I suggest go dig up some research papers first, then think about what to say.
They are serving PLA officers, acting as special correspondents for the TV station. 27-28 tons is his expert opinion. If I have to take your guess, anyone else's guess here, the CIA's guess, or his guess, he will win in my book any day of the week plus Saturday and Sunday. He did state the J31 specification hasn't yet been released. We can safely assume anything he said are officially sanctioned. Interestingly, he said any Japanese politicians daring to set foot on China's island territory risks being arrested and bought back to China to face justice. Things like that are no joke. You can be sure he represents official business.
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AssassinsMace
Lieutenant General
What I've read that seemed to have doomed the F-22 by the German Typhoon and the MKIs at Red Flag was using TVCs killed their speed. So is it always a plus and no negatives? No.
French is planning to install TVC for there rafale fighter.and rafale like J-20 both design around canard control.
Anything that can change aircraft attitude in two or more axes is called a 'flight control effector'...
Thrust vectoring made the jet engine such a device. This is what Song was trying to explain: The greater the amount of flight control effectors, the greater the maneuverability of the aircraft, and equally important, the better the survival of a damaged aircraft.
Keyword search: nasa f-15 active
What NASA did was bolted a pair of F-18 horizontal stabs to serve as canards on this F-15 and along with thrust vectoring, this modified F-15 has 9 flight control effectors: two vertical stabs, two horizontal stabs, two canards, two wings, and the engines. NASA used the canards to explore the maneuverability of increased effectors, more complex flight control laws, and how thru simulations a damaged flight control systems can automatically reconfigure itself to save itself, provided it has sufficient quantity of effectors.
The exploration was motivated by this inflight mishap...
The difficulty here is to write the flight control laws sophisticated enough to remove as much of the work load of flight control effectors choreography as possible from the pilot because that Israeli pilot had to devote all mental and physical resources to maintain stable flight. The laws has to be automatic enough to be transparent from the pilot yet be flexible enough to obey his commands to perform extraordinary maneuvers in every situations without killing him.
So yes, it is wrong to say that canards rendered TVC unnecessary.
When it's install then we talk about it.
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