J-20 5th Generation Fighter VII


Richard Santos

Senior Member
Registered Member
From a mechanical engineering point of view, it is possible to design the wing to be stiff so it wont flex. But it would be heavier and more bulky. If you can get away with some flex, it would reduce the weight of the aircraft, which is important for a combat aircraft. Also modern wings, especially when made with composites are designed to flex in flight for better aerodynamic performance. Just google Boeing 787 wing flex. It is meant to mimic how bird wings looks.

A wing that won’t flex require material with infinite modulus of elasticity, Which, not surprisingly, do not exist.
 

ougoah

Colonel
Registered Member
For visible flex it doesn't require infinite E. Even 1mm of edge deflection is really not noticeable. For typical fighter wings they are all designed to deflect a lot more than people realise. It's more than possible to develop a material that meets forces experienced in usual flight and undergo no visible deflection which is the real topic... obvious observable deflection rather than zero deflection.

Basically one member said wow the canards deflect... another went omg is that bad? is that a material problem? Allegedly the deflection is visible from cockpit camera angle. Don't worry. Not only are wings designed to flex, canards are too. In fact, even the fuselage deforms elastically to some extent.

1622704838295.png


Canards experience loading too. They also contribute to lift and exposed to various aerodynamic stresses. A more flexible wing is usually going to be more creep and fatigue resistant than the "equal material" that has higher tensile strength which would exhibit lower visible deflecting.

BTW deflecting obviously isn't referring to canard AOA delta but the deflection along its plane.
 

GTI

New Member
Registered Member
For visible flex it doesn't require infinite E. Even 1mm of edge deflection is really not noticeable. For typical fighter wings they are all designed to deflect a lot more than people realise. It's more than possible to develop a material that meets forces experienced in usual flight and undergo no visible deflection which is the real topic... obvious observable deflection rather than zero deflection.

Basically one member said wow the canards deflect... another went omg is that bad? is that a material problem? Allegedly the deflection is visible from cockpit camera angle. Don't worry. Not only are wings designed to flex, canards are too. In fact, even the fuselage deforms elastically to some extent.

View attachment 72888


Canards experience loading too. They also contribute to lift and exposed to various aerodynamic stresses. A more flexible wing is usually going to be more creep and fatigue resistant than the "equal material" that has higher tensile strength which would exhibit lower visible deflecting.

BTW deflecting obviously isn't referring to canard AOA delta but the deflection along its plane.
I had actually been thinking to suggest watching a video of a B-52 taking off, to whoever had first queried the flex. The little outboard wing landing gear aren’t even touching the runway well before rotation.
 

Richard Santos

Senior Member
Registered Member
For visible flex it doesn't require infinite E. Even 1mm of edge deflection is really not noticeable. For typical fighter wings they are all designed to deflect a lot more than people realise. It's more than possible to develop a material that meets forces experienced in usual flight and undergo no visible deflection which is the real topic... obvious observable deflection rather than zero deflection.

Basically one member said wow the canards deflect... another went omg is that bad? is that a material problem? Allegedly the deflection is visible from cockpit camera angle. Don't worry. Not only are wings designed to flex, canards are too. In fact, even the fuselage deforms elastically to some extent.

View attachment 72888


Canards experience loading too. They also contribute to lift and exposed to various aerodynamic stresses. A more flexible wing is usually going to be more creep and fatigue resistant than the "equal material" that has higher tensile strength which would exhibit lower visible deflecting.

BTW deflecting obviously isn't referring to canard AOA delta but the deflection along its plane.


Keep in mind for two material with the same yield and ultimate stresses, the one with lower modulus of elasticity, and greater elongation after yielding, is correspondingly able to store more energy before yielding, and absorb more energy prior to failure. So the component with lower modulus and higher elongation would tend to more resistant to battle damage.

So Making load bearing components of a military aircraft out of material of sufficient strength, but excessive stiffness, reduces the aircraft’s damage resistance,
 

by78

Lieutenant General
More rehearsal images. Do we have a date for the flyover?

51224851588_0eef950997_k.jpg

51223930867_d0b8649983_k.jpg
 

siegecrossbow

Lieutenant General
Staff member
Super Moderator
So they are back from Quzhou?

I don't know. Probably not. But this photo still contains useful info since it is taken recently. Not all of the Wuhu J-20s are rehearsing for the July 1st flyover this year since we see 15 of them rehearsing in Tianjin right now. This makes sense since sending all of them to Tianjin will leave the Eastern seaboard undefeated.

My hypothesis for J-20s participating in the parade:

1) 5 from Dingxin
2) 5 from Wuhu
3) 5 from Cangzhou
 

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