Carbon fiber, fiberglass, or what?

Discussion in 'Composites' started by pequeajim, Jan 31, 2007.

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  1. Feb 9, 2015 #41

    SVSUSteve

    SVSUSteve

    SVSUSteve

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    You have a point (Himat beat me to it though) but more often than not, especially in aircraft design, the issue isn't a matter of "the material is lousy!" but rather "the person designing it either ignored something or was lazy and chose the wrong or not enough material to satisfy a need". If you're looking for impact resistance and crash survivability using the techniques available to a homebuilder, then carbon fiber probably isn't the right material for that application. At least not as the only fabric.... There's no reason- barring some issue of incompatibility that I'm not aware of- that you can't use different fabrics on different parts of the same aircraft to achieve different goals. They do it on commercially built aircraft.
     
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  2. Feb 9, 2015 #42

    tunnels

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    If you want to learn what works and what doesn't, what materials and methods of building out last and don't come apart you should do repair work for awhile .Its the best teaching place there is !!, books and class rooms don't even come close and a lot of teachers wear blinker an cant see the who picture!!
    I can take and show you a pile of over a dozen surf life saving boats behind a boat company in nz that the Laminates were designed by on of the top and most experienced composite engineers I the business , everyone of these boats is busted beyond repair and all happened in a very short time of service!
    I was phoned by the owner of the company in shear desperation to come have a look and give advice of what was wrong . It took less than 2 minutes to see what the various problems were !. First the wrong glass was used, second the lay ups were 3 time as heavier as they should have been and the methods of building had no logical thinking gone into how to make it all stay together .
    Myself an there apprentice built 4 new boats out of the same moulds one after the other !! they were just 1/3 the finished weigh of the others , changed the glass to a much lighter non woven fabric , used standard polyester resin ,disregarded ha no core materials any where ad the carbon /nomex bull crap hi-tech transom that was coming apart , we used just 4 layers of unidirectional glass !!.problem solve!!

    If you believe everything you are told and read without doing any testing and finding out for yourself then you are in for a big shock one day when your least expecting it !!
     
  3. Feb 9, 2015 #43

    tunnels

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    Again the 3 most knowledgeable people i know here have answered truthfully and with wisdom ! Thank you and much appreciated .Every material has its uses just the some re better than others for various jobs!
     
  4. Feb 9, 2015 #44

    gtae07

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    Tunnels, I'm so grateful for your presence here. I had no idea how to go about learning composite construction techniques and how to properly design for them, but now I know that I just need to call upon your expert advice--you can just come eyeball my rough project and show me where to lay in a few more layers of glass. Your stunningly clear examples have left left me with no more questions--I'm ready to start!

    Or not.

    You come into the forums in multiple places, asking questions that might have had value if you were inclined to listen. But after getting answers from people who have been there, done that, and have the paper/hardware to prove it, you proceed to tell us how all of us are wrong and should instead just draw upon your (apparently shallow) font of knowledge and boatbuilding experience. And you do so in some nearly-unintelligible parade of characters drawn from the language that you imply you are a native speaker of and sprinkled with a semi-random repeating bursts of punctuation. Poor grasp of a language that is not one's own is one thing; your drivel is quite another.

    That's why nobody wants to listen to you, Mr. Tunnels. You're saying nothing.
     
  5. Feb 9, 2015 #45

    AVI

    AVI

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    "Tunnel(s) Vision" is indeed inspiring!!!!!
    "Why," I ask, "has he/she not been inducted into HBA as a SuperModerator?" ??!!!!!

    Thanks to Tunnels, I've already begun to modify my aircraft fuselage to more resemble a catamaran, or perhaps a trimaran!!! !!!! (Do we need a head and a galley???!!) I'm also seriously considering how to replace the standard, low aspect ratio, horizontal, fiberglass wing with a multi-ply, composite spinnaker molded in the shape of a fully inflated sail!!!!!! !!!!!!!!!!!
    The main obstacle so far, is the fabrication of the composite pylon on which to mount the mid-fuselage, reverse-tractor engine at a sufficient height to push huge volumes of air into the aft face of the curved spinnaker!!!!! Oh, the propeller ... Mr/Mz Tunnels, what materials, and how many overlapping plies should be used in the construction of the wood core propeller, considering that it will have to incorporate reverse pitch in order to direct air forward into the spinnaker???? !!!!!! I mean, we wouldn't have to run any numbers!!!!! You could just eyeball it, couldn't you?????!!!!!!

    I've also googled the ideal landing strip for the initial test flights!!!!! That was not easy to find!!!!!!! The criteria were dirt/grass strip ending at the face of a steep cliff overlooking the ocean with huge boulders at the base of the cliff!!!! It would then be possible to duplicate your rock n surf tests to determine how well the materials hold up!!!!! How many plies of Kevlar do you suppose we should apply to the cockpit floor????!!!!!!!!!

    Are you by any chance a pilot??? !!!!! With the tremendous amount of experience and bountiful knowledge you possess, perhaps you would be kind enough to conduct the first test flight !!!!!!!!!!!!!!!!!!!!!!!





    sorrry ... the Devil made me do it !!!!!!!!!!!!!!!!!!!![​IMG]
     
    Last edited: Feb 10, 2015
  6. Feb 10, 2015 #46

    tunnels

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    Just the sort of behaviour and answers I could expect ! puts you in your little boxes bit a like lab rats but they are useful !! !
    Yes can just take 2 minutes looking at a glass job to tell what its made from and what kind of people made it, and In that quick summery the approximate life expectancy !!
     
  7. Feb 10, 2015 #47

    BJC

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    Quote From the autobiography of the world's most accomplished boat builder.
     
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  8. Feb 10, 2015 #48

    AVI

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    The above must surely be a misquote due to error. It should undoubtedly have read:

    "Always the same blah blah from Tunnels all over this forum! Armchair expert and all he/she has to give is bad breath and hot air !
    Like most forums we have our no-hoper who just likes to see his/her name up on the screen, this one has more than posted his/her fair share of garbage !"
     
    Last edited: Feb 10, 2015
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  9. Feb 10, 2015 #49

    tunnels

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    I am me ! I know who I am ! I don't have to pretend to be something or some one im not or will never be !I know what I know about my job because I go beyond what others would never think of going , i even bought usb microscope to be able to get up close to understand the relation between resin and fibres and how it penetrates and saturates and the reason for small and large fibres and what they can do for you to make you work easer !! also the different types of core materials and how the resin penetrates and soak into balsa and the behaviour of core shear and the peelablity of glass off all of the most commonly used foams including Core matt. Nida core was really interesting and sure changed my mind as to its uses !
    Do you understand what the surface is like when you rip off peel ply and why it really doesn't have to be sanded before the next layer is put on and wet out !! What are just a few ways Peel ply can help you when laying glass ?? Is it worth using or not ??
     
  10. Feb 11, 2015 #50

    Retroflyer_S

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    How would Duramold made with epoxy fair with other composites ?
     
  11. Mar 16, 2015 #51

    pictsidhe

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    Anyone else know the old adage

    'It isn't what you've got, but what you do with it?'

    There is a huge choice of materials that can be used, IF the design is done well. Look at the Colditz escape glider. Bed slats, floorboards, bedsheets and the glue was aka 'breakfast'.

    Us, an odd bunch? What normal person designs and builds their own aircraft?

    My armchair beckons.
     

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