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How well do we really understand the materials we use ??

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Jan Carlsson

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for the last 20 odd years I have worked with professional people within the marine and industry composites industries and 90% of the work i have undertaken is to a survey standard or better !we had inspectors watching our every move taking samples of every resin mix and constantly checking everything all day long !!
So when I was asked to take over the position of project manager on 3 different jobs I to carried on the same tradition In all places I've worked ever since , I am constantly searching for information !
The building of a composite plane is completely new, the weights and types of fabrics are way outside anything I have ever experienced ! so that's my reason for asking so many questions .
finding the truth as it really is up sets a few people but it pays off in then end result !!
And you have got answers on all your questions!
 

davidb

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If I may interject, I gather from tunnels' last post that he is a production and quality control manager that has vast experience in boat production who is now involved with managing the development/production of a seaplane. If that is the case, it makes sense for him to broaden his knowledge base to include the norms for composite aircraft and seaplane design. He's found an excellent forum for that and I applaud those helping him. [A bit of forum diplomacy and honed communication skills on his part would help it go smoother.] I don't see any indication that tunnels has an engineering background, yet he certainly needs to be able to communicate effectively with the engineers of said project.

Tunnels, are there engineers involved with your project? If so, you should chat with them to understand why things are different than what your boat experience tells you is right. They will be counting on you to execute their "right way" with excellent quality control. Keep asking questions on this forum too. I'm learning a lot from the responses.
 

Apollo

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The building of a composite plane is completely new, the weights and types of fabrics are way outside anything I have ever experienced ! so that's my reason for asking so many questions.
And your questions have been answered by Billski and others. Asking the same questions repeatedly just annoys the engineers that have already posted extensive replies to your enquiries.

… finding the truth as it really is up sets a few people but it pays off in then end result !!
I don’t think anyone but you is getting upset by the truth about composite aircraft materials :)

Let’s try another approach: Tell us about your project. Provide details about the structures you’re building. Then the HBA engineers can respond with recommendations for that specific application. Are you building a flying boat? A seaplane? The more details you can provide, the better we can discuss appropriate materials (and the reasons why).


 

tunnels

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Never did get to the airplane manufactures as yet just have sorted lots there things in the mean time !! The weights of materials is still taking some getting my head around hats for sure !! I see lots of people quoting they are using unidirectional glass and makes me wonder why one fabric that's made at +- 45 double bias isn't used instead of laying 2 layers of uni at 45 to each other !ending up with the same thing but the manufactured fabric is stitched together so affords a little more shear strength !!
I have myself made lots of things from unidirectional glass set at all sorts of varying angles !
 

Vision_2012

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Never did get to the airplane manufactures as yet just have sorted lots there things in the mean time !! The weights of materials is still taking some getting my head around hats for sure !! I see lots of people quoting they are using unidirectional glass and makes me wonder why one fabric that's made at +- 45 double bias isn't used instead of laying 2 layers of uni at 45 to each other !ending up with the same thing but the manufactured fabric is stitched together so affords a little more shear strength !!
I have myself made lots of things from unidirectional glass set at all sorts of varying angles !
FYI, we are not "airplane manufacturers" when we build ONE airplane from plans for our personal use. One cannot compare homebuilt aircraft processes with profit making certified manufacturers.
It is not cost effective to buy UNI, 45 two-ply Uni and Tri-Ax. So we buy UNI an BID and use it. The only source I found for Tri-Ax wanted a 100 yd minimum order, which would be a 80 yd waste. So my wings are made from two plies of UNI and one of BID. Your use changes when you and not a company is paying the bills. Also, we not only are the person paying the bills, but the engineer, lay-up tech, inspector, and shop janitor.
 

TFF

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Even a company cant use the best of everything unless you are building F1 cars. Everything has a price point.
 

tunnels

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Like I have pointed out before how many people actually check the materials they bought are what is listed !! is it right weigh or do we just take the sellers word for it ?? To understand glass cloths and fabrics better I bought a computer plug in microscope ! wow seeing things in real lose up detail is rather interesting and opened my eyes for sure ! also the bundles of fibres and watching resin soak its way along through a bundle of glass filaments till it was completely saturated end to end .I like my job and the more I find out the easier It is to understand why small problems happen and I can solve the issues so they don't happen again !!
 

Apollo

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I see lots of people quoting they are using unidirectional glass and makes me wonder why one fabric that's made at +- 45 double bias isn't used instead of laying 2 layers of uni at 45 to each other !ending up with the same thing...
Short answer: Two plies of uni at +/-45 degrees are stiffer and stronger (along their axis) than an equivalent amount of bi-directional fabric (BID) at the same angle. Why? Because fabric fibers are generally not straight when compared to uni. Fabric is woven and this results in over/under bends in the individual fibers. Uni has mostly straight fibers, so it provides greater strength and stiffness than an equivalent weight of BID cloth.
 

jack.39

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We have a nice resort hotel here where we live, named the AVI! Could it have influenced Mr. AVI's choice of User Name?


" its where good things are happening at an alarming rate." Such as unbridled environmental destruction?

"besides becoming the most annoying poster at HBA? " Such distinction is likely held in abeyance, until my own proclivities become evident! jack
 

tunnels

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Fabric is woven and this results in over/under bends in the individual fibers. Uni has mostly straight fibers, so it provides greater strength and stiffness than an equivalent weight of BID cloth.

In all my years of glassing I have never ever seen woven double bias fabrics !!!so that's first !!
Woven fabrics are by nature less stiff than straight flat laid glass in any type of stitched fabric be they 2 ,3,or 4 layers in 4 different directions !!
You missed the fact that you can buy double bias ready made instead of laying two separate layers of unidirectional one after the other and the readymade could possible be using fractionally less resin but it will be stronger because of the stitching holding the layers of uni glass together !!
How many people use peel ply over the top of there laminate ?? you do realise peel ply is compacting your glass layer and holding It down till it goes hard Plus it easier to see bubbles and get the air out!! it also shows resin rich or dry patch's so you get a much more even consistent wet out and more uniform layer !!
 

tunnels

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We have a nice resort hotel here where we live, named the AVI! Could it have influenced Mr. AVI's choice of User Name?


" its where good things are happening at an alarming rate." Such as unbridled environmental destruction?

"besides becoming the most annoying poster at HBA? " Such distinction is likely held in abeyance, until my own proclivities become evident! jack
My God its another one !! please take your soap box to some other post and stay focused on the topics an subjects we are talking about !! Thank you !
 

AVI

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We have a nice resort hotel here where we live, named the AVI! Could it have influenced Mr. AVI's choice of User Name?

jack
Nope. Nice country down there. Visited AZ not too long ago but I've never heard of AVI resort.
The only Mojave I know of is out in the California desert.
Was your resort named after me? :)
 

Vision_2012

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" In all my years of glassing I have never ever seen woven double bias fabrics !!!so that's first !!"
Yes, but do you buy the materials with your own money or is it bought for you? Comparing manufacturing with homebuilt a/c leads to many differences and compromises in design. Show us a personal project not a professional one.

"You missed the fact that you can buy double bias ready made instead of laying two separate layers of unidirectional one after the other and the readymade could possible be using fractionally less resin but it will be stronger because of the stitching holding the layers of uni glass together !! "
Again, where can one buy two ply 45 degree biased UNI by the yard? You don't get the economy that homebuilders are limited by. We have sources like Aircraft Spruce & Specialty, Wickes, etc. that we have learned to trust for quality and business.
 

BJC

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My God its another one !! please take your soap box to some other post and stay focused on the topics an subjects we are talking about !! Thank you !
Alternatively, you, Mr. tunnels, could go back and read all the answers to all your questions, stay focused on them until you understand them, and then engage in rational discussion here on HBA.


BJC
 

AVI

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The single word composite isn't even mentioned !!
and if I have to stay focused on an answer its not worth reading !!
Have you, by any chance, Mr. Tunnels, considered simply logging out?

We aren't exactly sure what your message is. We do not know what your agenda is. We do not know what you're attempting to accomplish, and
at this point, it would appear that you're going to have an extremely difficult time trying to convert or enlighten us with your wealth of knowledge and experience.
Why? Well, maybe we just do things a lot differently over here. Who knows? Perhaps we simply do not know any better. Ignorance is bliss, so they say.

However, in spite of the fact that we are not enlightened as such, our methods and materials do work remarkably well in our shade tree workshop environment.

Have you considered searching the HBA archives in your self-proclaimed quest for knowledge? Have you considered lurking and studying posted material?
Lurking anonymously in the background is, from what I've been told, an excellent method of accumulating specific knowledge without obnoxiously bombarding members with, to put it politely, a steady stream of pure crap.
 
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Vigilant1

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getting answers is le getting blood from stone so the Good news is could be going to visit a couple of light plane manufacture's next month and maybe i'll find out what they are doing and using and score some samples to bring home with me !!
I know you'll make quite an impression.
 
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tunnels

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I know you'll make quite an impression.
my work and what I do deals In real facts as they are ,like the truth ! and figures that are also real learned from actual doing the work ,not read from books or second hand stories that have been handed around for the last 10 years !! Wasting words and filling pages just for the hell of looking important is fruitless and time wasting , But every now an then some one has really good information to share and is very informative and interesting!!
 
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