China Flanker Thread II

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plawolf

plawolf

Lieutenant General
KIENCHIN said:
Hi Deflt, the J10B/C has a large proportion of the upper wing in composite and vaguely remember possibly the same under wing. Please see Sinosoldier and Dieno's post on the J10 thread. Is this because the J10 B/C is a more advance aircraft and we will probably see the same amount of composites in the J11D. From a layman point of view, the one thing I had observed is the increasing amount of composites used with each subsequent model upgrade and this is a good sign.
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I think the gradual increase in composites is more to do with supply of the materials, rather than any structural or design limitations.
 
SinoSoldier

SinoSoldier

Colonel
delft said:
The wing is largely hollow, fit to be filled with fuel. So imagine it as a box, the wing box. Then bend the wing box: The strain is largest at the outside of a wing box: at the upper and lower skins.
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That makes sense. I completely missed the fact that the wings are filled with fuel.
 
D

delft

Brigadier
KIENCHIN said:
Hi Deflt, the J10B/C has a large proportion of the upper wing in composite and vaguely remember possibly the same under wing. Please see Sinosoldier and Dieno's post on the J10 thread. Is this because the J10 B/C is a more advance aircraft and we will probably see the same amount of composites in the J11D. From a layman point of view, the one thing I had observed is the increasing amount of composites used with each subsequent model upgrade and this is a good sign.
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The aspect ration of a delta wing is much lower than that of J-11 which makes designing a composite upper wing skin much easier.
 
D

delft

Brigadier
antiterror13 said:
Would you kind enough to elaborate ? for people (like me) who don't know much of composites
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Composites are thin and therefore flexible fibres in a matrix of in this case plastic ( there are also metal matrices but these are not relevant here ). When a part is under compression the fibres must be prevented from buckling by the matrix. This leads to a lower maximum stress level under compression than under tension and the disadvantage from that can be minimized by careful shaping as well as by improvements in the matrix material. Shaping includes that of stiffeners attached to or part of the skin.
My Idea is that you should forget about the ribs and stringers used in Aluminium wing structures and look at the wing structures as developed by Barnes Wallis and used in the Vickers Wellington.
 
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A

antiterror13

Brigadier
delft said:
Composites are thin and therefore flexible fibres in a matrix of in this case plastic ( there are also metal matrices but these are not relevant here ). When a part is under compression the fibres must be prevented from buckling by the matrix. This leads to a lower maximum stress level under compression than under tension and the disadvantage from that can be minimized by careful shaping as well as by improvements in the matrix material. Shaping includes that of stiffeners attached to or part of the skin.
My Idea is that you should forget about the ribs and stringers used in Aluminium wing structures and look at the wing structures as developed by Barnes Wallis and used in the Vickers Wellington.
Click to expand...

Thanks. My real question is why "Impressive" from expert point of view? as @Zahid claimed
 
Air Force Brat

Air Force Brat

Brigadier
Super Moderator
delft said:
The wing is largely hollow, fit to be filled with fuel. So imagine it as a box, the wing box. Then bend the wing box: The strain is largest at the outside of a wing box: at the upper and lower skins.
Click to expand...

Lots to think about here, for clarification the "center wing box" or "center-section" of the wing is the "spar carry through" that is attached to the fuselage structure, where the wing and fuselage are joined. The outer wing panels usually bolt on, or are "pinned" to the "center wing box".

For a "wet wing" that carries fuel without a separate fuel tank, the stress is greatest naturally as the gross weight of the aircraft increases. As well a "wet wing" that is filled with fuel is marginally stronger, than a "wet wing" that is empty.

So every wing has a load bearing member, normally a "spar", but on composite wings it can simply be a "thicker section" that is designed to carry the "load" and transfer that load back to, and through the wing "center section"/fuselage join.

Most fighter aircraft have a longitudinal heavy stringer as the "back-bone" of the aircraft, and all loads are ultimately carried by this "back bone", much like your own "spine".

When an aircraft increases the G force it is experiencing, that added force is concentrated at the wing root, and contained and the load dispersed "though" the airframe by the underlying supporting structure, traditionally a "main spar/forward spar", ribs, and skin which are almost always "load bearing" members.
 
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