Trace based simplified composite analysis. Opinions?

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stanislavz

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Even the same tech at the same temperature and humidity laying up the same part can have variations in the quality and consistency of each layup.
Same was written by Jim Marske in comparision of carbon fibre spar as designed to tested ones.. And solution of pultruded carbon rob come to live. And no, it is not expensive at all.
 

stanislavz

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Inspired by Caro wing. An comparison of wing skins for chord 1300mm, 13.5% thick. Piece of span 750 mm.

Foam less :

1600080053285.png

Reinforcement ribs load :

1600081051130.png

Ribs :
1600081332590.png
Laminas :

1600080090438.png

With foam :

1600081138155.png

1600081191057.png


Load and boundary condition

1600081398308.png

Load is shown inccorectly, its starts from 0.006N/mm2 at the nose and ends at leading edge. Formula is z=(1300-y)/1300/-0.006

For easier calculation, nose section was ommited, and reinforcements were modelled as section with know property.

And yes, it would look different for single spar wing.
 

stanislavz

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Once more, this time for full section, for strut braced wing with jury struts. Only one section

1600094120971.png
1600094325366.png

with foam

1600094363071.png

1600094376482.png

span is 1300 mm, weighs are 5.17 kg for section with foam, and 5.6 for section without foam. In real world , with foam will be bigger ?

Deflection is close, but not similar. Mine tubes weight 0.066 kg per m, and this same as ribs from two plies of 300 gsm..
 

stanislavz

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Added two more ribs, but made all five from 2 plies of 300gsm biax, in stead of 4:

1600099991084.png

1600100009706.png

1600100070910.png
 

stanislavz

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One more run, to minimize parts / operations counts.

Two spar wing, Front is core/rib less D cell, first spar is place ad 120 mm, of 1300 mm chord wing. It is build from two layers of 300 gsm biax of main skin + 2 x 300 ud at 90 degree for rigidity.

From front spar to rear spar - only 300 gsm skin + rib each 200mm.. Ribs olso build from 300 gsm biax.

Skin with front D cell molded as one piece, ribs/shear webs molded in place. With some corrugations for buckling stability.

It shows ~ 10 kg for skin and ribs, per wing for 12.5 m2 wing..

1603839832475.png
 

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Fireflyer228

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My last post on this thread. On my phone it looked like it was recent and on this website I can't edit my posts after a few minutes. It makes me a little crazy when I re-read my posts and it looks like a child wrote it. Sorry for my random post. I didn't mean to detract from the topic. I won't be doing that again.
 

stanislavz

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Did some literature overview - if single skin is used as fabric replacement (non-load bearing, heavy ribs underside), and most numbers looks like this for fiberglass - skin done from two layers of 10 oz / 300gsm fabric with ribs spaces from 225 to 300 mm. Aircraf reviewed - bd4 (recomennded to add one more layer / or rib ), ol' ironoside, Maerske monarch (300mm of ribs spacing in first versions, reduced 225 mm in later ones), Strojnik S4 (250mm, laminar flow).

And, yes it did holds air loads, and planes are ok with this solution, some were able to have laminar flow.

But - here goes the champion from other side - Cri-cri. 0.5mm aluminium skin, bonded to 6mm pvc foam ribs spaced each 45/90 mm.

And results, which are fun to me. A direct comparison of aluminum to black aluminum (0.5mm skin to 0.5mm skin) :



1604239949088.png
1604239973873.png

Winner is black aluminum.
 

stanislavz

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More on wing skins. As one of my teacher learn me - you result in fea is as good as model you did described.

So on wing skin - i did remember of my first airplane, it have ugly airfoil, done from two radiuses :

1605721536607.png

Same simplified model drawn for GA 30-413.5, 1.35m chord.

1605721575791.png
And radiuses are :
1605721673082.png
 
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