ColinB Posted June 28, 2009 Share Posted June 28, 2009 Are most of you using plain weave or 2x2 twill? 2x2 has less of a crimp between the weaves and would appear to be the superior choice whats the general opinion on this? Quote Link to comment Share on other sites More sharing options...
TMann Posted June 28, 2009 Share Posted June 28, 2009 whats the general opinion on this? To use what is called out in the plans.Hexcel 7715 & 7725 Quote T Mann - Loooong-EZ/20B Infinity R/G Chpts 18 Velocity/RG N951TM Mann's Airplane Factory We add rocket's to everything! 4, 5, 6, 7, 8. 9, 10, 14, 19, 20 Done Link to comment Share on other sites More sharing options...
ColinB Posted June 28, 2009 Author Share Posted June 28, 2009 To use what is called out in the plans. Hexcel 7715 & 7725 and 7715 is plain and 7725 is 2x2 twill from reading the hexcel site Quote Link to comment Share on other sites More sharing options...
TMann Posted June 28, 2009 Share Posted June 28, 2009 and 7715 is plain and 7725 is 2x2 twill from reading the hexcel site Good .... sounds like you've got it. Quote T Mann - Loooong-EZ/20B Infinity R/G Chpts 18 Velocity/RG N951TM Mann's Airplane Factory We add rocket's to everything! 4, 5, 6, 7, 8. 9, 10, 14, 19, 20 Done Link to comment Share on other sites More sharing options...
Kent Ashton Posted June 28, 2009 Share Posted June 28, 2009 and 7715 is plain and 7725 is 2x2 twill from reading the hexcel site Sounds like some confusion here Check the ACS catalog, p. 30 7715 is Unidirectional - All the fiber go one direction except for small fibers to hold the cloth together. You could call it a plain weave but the cross fibers don't do anything. it's always called "UNI" 7725 is Bi-directional (BID), a twill weave, i.e., a modified over-and-under weave. Used because it drapes better than a plain over-and-under weave. Quote -KentCozy IV N13AM-750 hrs, Long-EZ-85 hrs and sold Link to comment Share on other sites More sharing options...
ColinB Posted June 29, 2009 Author Share Posted June 29, 2009 thanks that clears that up then Quote Link to comment Share on other sites More sharing options...
argoldman Posted June 29, 2009 Share Posted June 29, 2009 This probably goes without saying---- Each glass weave has specific strength characteristics and were chosen by the designer((s) to achieve specific goals. Do not interchange them, or substitute them without proper knowledge in things glass fiber. Rich Quote I Canardly contain myself! Rich Link to comment Share on other sites More sharing options...
ColinB Posted June 29, 2009 Author Share Posted June 29, 2009 Im not using glass im using prepreg carbon, so i will be substituting materials however the info on the hexcel material has helped me a great deal, thanks Quote Link to comment Share on other sites More sharing options...
TMann Posted June 29, 2009 Share Posted June 29, 2009 Im not using glass im using prepreg carbon, so i will be substituting materials however the info on the hexcel material has helped me a great deal, thanks Yes, the hexcell site has all the spec sheets.The Berkut used the CF 716 UNI in place of the 7715 glass for the wing skins in a slightly different layup schedule. 716 is prepreg. Une of the downside of CF is that you can't hide the antenna under the skin. Quote T Mann - Loooong-EZ/20B Infinity R/G Chpts 18 Velocity/RG N951TM Mann's Airplane Factory We add rocket's to everything! 4, 5, 6, 7, 8. 9, 10, 14, 19, 20 Done Link to comment Share on other sites More sharing options...
mak790 Posted June 29, 2009 Share Posted June 29, 2009 716 is prepreg.Isn't it carbon uni fibre? Not prepreg.http://www.hexcel.com/www.hexcel.com/Fabrics_DataSheets/716.pdf http://www.aircraftspruce.com/catalog/cmpages/unicarbongraphite.php in a slightly different layup schedule.I've heard about 3 carbon BID layers insted of two 7725. What did they use in place of the 7725? Was it 282 or 284? Quote Link to comment Share on other sites More sharing options...
TMann Posted June 29, 2009 Share Posted June 29, 2009 I've heard about 3 carbon BID layers insted of two 7725.They don't use 7725 on the wings. Only UNI. Quote T Mann - Loooong-EZ/20B Infinity R/G Chpts 18 Velocity/RG N951TM Mann's Airplane Factory We add rocket's to everything! 4, 5, 6, 7, 8. 9, 10, 14, 19, 20 Done Link to comment Share on other sites More sharing options...
mak790 Posted June 29, 2009 Share Posted June 29, 2009 They don't use 7725 on the wings.I know they don't/didn't use 7725, but I thought that they replaced glass BID 7725 with Carbon BID 282.Only UNI.So I understand they used 3 layers of UNI, first at 45deg, second at 0deg, and third at -45deg. Do you remember exact order? Quote Link to comment Share on other sites More sharing options...
ColinB Posted June 29, 2009 Author Share Posted June 29, 2009 the first ply is 30degrees from center line the second ply is in opposite bias the 3rd ply is span wise this is for the moldless berkut wing this is in uni carbon Quote Link to comment Share on other sites More sharing options...
mak790 Posted June 29, 2009 Share Posted June 29, 2009 Thanks Colin, I completely forgot, about 2-3 years ago there was a discussion at Canaraviation forum about the Berkut wings Layup, Richard Rilley said that fabric was laid at 30 and -30 deg, unfortunately he remowed all his post there, and because he passed away last December I can't ask him about it. I remeber that he said also, that the Berkut had 8 layers of fabric in the shear web, not 6 like the Long Ez. That's all what I remember. Seb Quote Link to comment Share on other sites More sharing options...
mak790 Posted June 30, 2009 Share Posted June 30, 2009 I've heard about 3 carbon BID layers insted of two 7725. What did they use in place of the 7725? Was it 282 or 284? Wow I just checked my Long Ez plans, I haven't seen them for 6-8 months. I'm not into Long Ez any more. Seems that, there is only UNI in the wings, I'm wondering where is that 7725 come from, hmm Quote Link to comment Share on other sites More sharing options...
longez360 Posted June 30, 2009 Share Posted June 30, 2009 Are most of you using plain weave or 2x2 twill? 2x2 has less of a crimp between the weaves and would appear to be the superior choice whats the general opinion on this? I used 2x2 twill 12k tow carbon on some parts. Yes, the crimp is less. I used some non-crimp material with veil as well, but I used very different resin and cure cycle. My suggestion is stick with plans materials for structure unless you are ready to commit to enough testing that would substantiate it's inclusion. Generate allowables, or bridge test to show equivalence. Not sure that's worth the effort. Quote Cheers, Wayne Blackler IO-360 Long EZ VH-WEZ (N360WZ) Melbourne, AUSTRALIA http://v2.ez.org/feature/F0411-1/F0411-1.htm Link to comment Share on other sites More sharing options...
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