Wing Architecture Selection 2

[BAYU7]

Hi,
I am analysing diferent configurations of multi-spar Wings, and I am making a comparison between a wing based on convergent spars and other one based on parallel spars.

At first sight, it seems than a parallel configuration would optimize the design of the skin panels (CFC) if these are sized by buckling, but it seems that you have to increase a lot the weight of the sub-structure due to the high number of spars in comparison with a convergent architecture, that would reduce the number of spars, although perhaps would penalyze the weight of the skin panels.

Please could anybody give some guide to check wich would be the better architecture?

Thanks in advance

 

[SWComposites]

What is your definition of "better"? cost, weight, damage tolerance, ??

What type of aircraft?
Is there fuel in the wing box?
Are there engines on the wings?
Are there other point loads on the wings (weapons racks, etc.)?
How is the wing box going to be assembled (bolted, bonded, one-piece)?

This kind of design trade study is very complex, and the result and conclusions will depend on the specific design criteria, goals and objectives, and with the selected fabrication processes.

 

[rb1957]

you may want to compare the wing structure of a Lear31 and a Lear45 ... the eariler 31 design is based on a fighter multi-spar wing, the latter 45 was designed as a two spar wing (ok, 2 & 1/2).

I think a multi-spar wing is more tolerant of battle damage, but most commercial jets don't need that !

The minimum number of spars and careful design of the wing stringers produces the minumum weight.

But as SWComposites notes above there are a Huge numbers of things that affect that statement !! Another consideration is that convergent spars on a tapering wing tend to be easier to manufacture than parallel ones (which have varying wing surface tangents to adapt to).

 

[BAYU7]

Thanks for youre reply, in principle the question is a theoretical question, so no fuel on wing, no hard points, no engines, and the idea could be to have a CFC skins and a metallic sub-structure.
My question would be to know the pros and contras of an architecture based on convergence spars and other one based on parallel spars and the impact on terms of weight.

 

[rb1957]

i'd say the 1st consideration is wing planform. a tapered wing obviously lends itself to converging spars, a rectangular wing obviously suggests parallel spars. parallel spars on a tapered wing would be more difficult to manufacture, but as you say this isn't a real problem. converging spars on a rectangular wing would allow you to reduce the torsional stiffness of the wing towards the tip, if you wanted to, maybe to get some aeroelastic deflection happening (dynamic load relief?).
weight-wise i don't think there's much in it.