J-20 5th Generation Fighter VII

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Richard Santos

Captain
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siegecrossbow said:
They were done with afterburners. It is just that the flames aren’t visible due to the lighting.
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In actual service, air combat maneuvers like these would be done only in relatively close combat, and then it would be done mostly without afterburners to avoid giving marginal IR shots an increased chance of hitting it. You would only light up afterburners if you lost a lot of energy and must gain the energy back quickly regardless of consequences.

Afterburners should be thought of as mostly an emergency device in combat, not something you light up whenever you feel the need for speed.
 
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Volpler11

Junior Member
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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.
 
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Richard Santos

Captain
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Volpler11 said:
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.
Click to expand...

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

Brigadier
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.

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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.
 
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GTI

Junior Member
Registered Member
ougoah said:
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.
Click to expand...
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.
 
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Richard Santos

Captain
Registered Member
ougoah said:
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.
Click to expand...


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

by78

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

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