J-20... The New Generation Fighter II


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MiG-29

Banned Idiot
Actually, at 1:46, the canards do seem to be at different angles. One side got the sun reflection first, then the other side.

But who knows, I don't claim to have super eyes (unlike you) to say one way or the other.
Let us see facts. all aircraft with canard foreplanes, can use them as roll control, however due to wing canard interaction the roll control is negligible, thus they need to resort to elevon control (trailing edge flaperons),the J-10 and well as the Eurofighter or Rafale and Gripen can use their foreplanes as roll control devices, however they usually leave that task to the elevons.
In the video you can see the canard not moving simply because the J-10 wing can be used as the wing of a Mirage 2000 or LCA and achieve roll control without the use of any canard input.
tailplanes are different and in that aspect more effective, because their wake does not down wash the wing its use is less restricted
you can see it in the same in the Eurofighter

[video=youtube;8JXOssmp5Io]http://www.youtube.com/watch?v=8JXOssmp5Io&feature=related[/video]
 
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delft

Brigadier
I found the discussion on drag coefficients somewhat simple. There is the drag due to friction, as recognized by MiG-29, more drag is due to lift. which is extremely important during manoevers, and wave drag is important when you go supersonic and is dependent on volume and the distribution of that volume over the length of the aircraft (greater length is better there ). Total drag is the sum of those and their relative and absolute sizes vary greatly.
 

johnqh

Junior Member
Let us see facts. all aircraft with canard foreplanes, can use them as roll control, however due to wing canard interaction the roll control is negligible, thus they need to resort to elevon control (trailing edge flaperons),the J-10 and well as the Eurofighter or Rafale and Gripen can use their foreplanes as roll control devices, however they usually leave that task to the elevons.
In the video you can see the canard not moving simply because the J-10 wing can be used as the wing of a Mirage 2000 or LCA and achieve roll control without the use of any canard input.
tailplanes are different and in that aspect more effective, because their wake does not down wash the wing its use is less restricted
you can see it in the same in the Eurofighter

[video=youtube;8JXOssmp5Io]http://www.youtube.com/watch?v=8JXOssmp5Io&feature=related[/video]
So you just ignore what I pointed in the video you posted?

Roll control is not for when the airplane is rolling only. Under different flying conditions, different control surfaces can have different results. If designing an airplane is so easy, you would be a real designer.

For one, controlling canards will not only generate roll force, but also change the strength of the vortex. So, most designers will only use flaps for roll under normal flight conditions, but can work the canards in under high AoA.

By the way, don't use other fighters video to make your argument. There isn't any evidence that any other canard/delta fighters have the ability to move canards independently, so really, what's your point?

And I have noticed that you have ignored quite a few posts which you couldn't respond. Good job on debating!
 
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Engineer

Major
In this two videos you see the J-20 doing rolls at flight it never uses the canards differentially, and the main reason is it does not need it, the elevons are enough to do it without lift losses or drag increases as canard deflection would mean see by your self
You don't see the flaperons move either. Low resolution videos don't allow you to see any detail, but the fact that you cannot see anything does not support your argument that the canards aren't use differentially.

Note the J-10 when it take offs move its canards more than 15 degrees are quit noticeable, so there is not such thing they will use 1 degree of differential deflection to roll, it simply does not use canards, and it does it to keep lift at its max and leaving the elevons do the job without any loss of lift
Of course canards can be used for roll, and you don't see it because
  1. the J-10 in the video is taking off, not rolling,
  2. deflection of canards at higher speed, where rolling usually take place, is much smaller than deflection at lower speed when the aircraft is at V2,
  3. the videos are very low resolution and taken from very far away that you don't see movement of any control surfaces.
Instead of cherry picking videos from youtube, show some real proof that the differential canards can't be used on roll instead.

For the J-20 the V tail will do the job of pitch control as the F-18 does it at take off
All the control surfaces on the J-20 are involved in all the maneuvering, including roll and yaw.
 

Engineer

Major
Let us see facts. all aircraft with canard foreplanes, can use them as roll control, however due to wing canard interaction the roll control is negligible, thus they need to resort to elevon control (trailing edge flaperons)...
There's no evidence that roll control from canards is negligible. Flaperons being used in roll control is not evidence that canards cannot be used in roll control.

the J-10 and well as the Eurofighter or Rafale and Gripen can use their foreplanes as roll control devices, however they usually leave that task to the elevons.
In the video you can see the canard not moving simply because the J-10 wing can be used as the wing of a Mirage 2000 or LCA and achieve roll control without the use of any canard input.
None of the above planes other than J-10 have differential canards, and therefore only the J-10 can use its canards in roll control.

tailplanes are different and in that aspect more effective, because their wake does not down wash the wing its use is less restricted
There is no such evidence that say tail planes are more effective in roll control than canards.
 

Engineer

Major
Any one feel like translating our 7 page banter for our Chinese friends :D?
Their entire thread is about how machine translation sucks, lol.

But really, as one poster there pointed out, there isn't anything of substance in the current "debate". It just consist of one person who wants to see things that are not real coming up with irrelevant facts to support his belittling of J-20, and us picking apart his arguments. For example:
Person in question: Everything encounters drag, therefore J-20 has higher drag.
Us: Everything encounters drag is not a proof that J-20 has higher drag.
 
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