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Fiberglass streamliner motorcycle

Discussion in 'Modifications and Projects' started by Salad Cycle, Jan 31, 2015.

  1. Hello, I want to get some recommendations regarding the number of layers and type and weight of fiberglass layers (chopped/uni/bi/multiple directional) for a streamlined motorcycle fairing.

    Something like this: [​IMG]

    I have found this vital information difficult to come by. So help is appreciated.
  2. Don't use chopped strand mat. It's inefficient (read: heavy for a given strength and stiffness) and looks crap where the weave is visible.

    Personally I'd go with a fairly light cloth, with a weave that allows it to follow compound curves, and use at least a couple of layers at 45 degrees to each other so there are fibres in multiple directions. It would be possible to economise a bit by working out which way the major stresses go but I doubt if I could be arsed. I'm an engineer by profession but constructional stuff for my own projects I tend to work by rules of thumb, past experience and that ever elusive quality, "feel".

    Polyester resin will do the job fine but do treat the chemicals with respect. The hardeners and catalysts used, particularly, are fairly nasty. Epoxy is nicer to work with and has better mechanical properties but it's spendy. Not ludicrously so in the quantities needed for a bike shell though.

    Number of layers and hence laminate thickness depend on what you're doing with the bike. A road bike, expected to survive a hundred thousand kms of everyday wear and tear will need something more robust than a salt lake special which gets run once a year and where weight is critical. Best bet would be to go to your nearest track on either a track day or a club meeting where the public can wander around the paddock. There'll be a zillion sets of race glass there and looking at that will give you a better idea of what's required, along with plenty of ideas for mountings and hardpoints which you can adapt to your own application.

    If you haven't done much fibreglass work. Try getting a selection of materials and have a play around making small bits and pieces, for example a seat unit or a mudguard, to get a feel (that word again) for the techniques and an idea of the strength of the finished product.

    Now, how confident are you in your ability to get the aerodynamics right? Streamliner shells and dustbin fairings have plenty of potential to kill you. Both the effects of side winds and any tendency to become airborne can become rather exciting and, almost by definition, you're likely to be going quite quickly when they do.
    • Like Like x 1
  3. shop around for your consumables -- 20L cans are a lot less than 100 times the price of 200ml cans.
  4. Talk to a boat building shop. Hydrodynamics is pretty important to those guys.
  5. is it for max speed racing? or day to day?
  6. Consider also the resin. Vinyl Ester, AKA Derakane, has a bit more flex than Polyester which can be brittle. In effect, that makes it quite a bit stronger where vibration, impact or flex is an issue. It is compatible with all of the usual fillers, like talc (too heavy) or glass beads like one would use in polyester, whereas the fussy people who use epoxy suggest using only epoxy compatible pigments. It is also activated by bog standard MEKP activator. Clean up also with acetone. It is simply a better resin.

    3 laminations of light cloth is enough. You can get CSM in different weights. The lighter stuff is not so stiff. You won't find it at Bunnings however. People often sandwich a layer of CSM between 2 layers of cloth.

    The key is to use a minimum of resin - enough so that there are no voids in the laminations and no pools of resin. For this reason, many builders use a vacuum system to press the laminations against the mould and do all the layers in one go. It can be really low tech - air compressor, garden hose, plastic sheet, sealant. This guarantees you get all the air out and makes it possible to produce thin, strong parts with a minimum of resin. It's much more effective than rolling. You'd be surprised at how much less resin you can use, and it's fast.

    If the panel was made of polyester/glass, I'd want the hard points/mounts to be based on Vinyl Ester. It is completely compatible with polyester, except in flow coat applications - ie. polyester that has paraffin in it as is used to finish the inside of boat hulls, giving the chopper gun applied CSM a smooth finish. For small articles you'd be hand rolling or vacuuming the layers down.

    Get friendly with a boat builder, particularly those who build high tech canoes for racing or racing yachts. They will have a lot of expertise and may be willing to sell you materials, which can be a bit hard to source otherwise.
    • Informative Informative x 1
  7. Thank you for your great replies.

    Purpose: Upgrade for day to day use. Better fuel efficiency, better wind protection, better top/cruise speed and it will look awesome if I can pull it off.

    Sometimes I get obsessed with learning how to do or build something and this is such a project.

    I have never used fiberglass before. I have found a lot of supplies on ebay including that Vinyl Ester resin.

    I'll research vacuum molding and see if I will be be able to benefit from this method.

    I am not currently knowledgeable enough regarding aerodynamics to know how to apply the optimal angles to the motorcycle frame.

    I just had an idea for how to make the mold.

    If I can get transverse cross sections of an accurate design then transfer that to cardboard with blocks of foam between them. I'd be able to mount it to the motorcycle frame and use the cardboard as a guide as well as cut away sections of the foam to provide space for legs/wheels etc. With the cost of polystyrene/polyurethane this could help cut down on material costs.
  8. paper Mache is your friend
  9. I have a suggestion; start with something smaller like some glass panniers to get a feel for it.
    • Agree Agree x 1
  10. Hi Salad Cycle.

    Forgive me if you already know of this, but Craig Vetter,
    http://www.craigvetter.com/index.html is the sort of guru for this kind of stuff.

    I dunno if he covers exactly what you want to know....... sorry.
    • Agree Agree x 1
  11. One last thing, There is a book - Building Small Boats, Surf Craft and Canoes in Fibreglass by Jeff Toghill and John Flett ISBN 0 7301 0123 1 It's about 100 pages.

    This is very good on basic techniques and materials. An excellent "primer". Takes you though the whole process of making and finishing the "plug", creating and finishing the mould and using it to produce the moulded article. I would regard this as an "essential read" for the absolute beginner.

    Where it falls short is in its focus - There is little discussion of resin options - ignores Vinyl Ester and Epoxy altogether and there is nothing about vacuum moulding, or modern materials like Carbon Fibre or Kevlar. The book is dated. (1981) However, the basic techniques remain unchanged, and the issues related to mould design, finishing, and mould release are still the same.

    The book is really about empowering the backyarder to make things in GRP

    You might find it in a library, or try Amazon.

    Also a useful tool, - rollers - the best rollers I've had were parsley cutters with the flat plate removed - you can sometimes find them in second hand shops in the junk kitchenware.
    • Informative Informative x 1
  12. Brown vinegar saves you $.
  13. There's a fair bit of stuff on the web about vacuum bagging. It's a popular technique with the homebuilt aircraft crowd 'cos it minimises the ratio of heavy, weak resin to strong glass fibres.
  14. This got me going; what the hell are parsley cutters?
    Goggle here I come; Google "parsley cutter" Images search. Hmm, what the frarck!

    Nope, don't think so.


    Not this either.




    Don't think so?

    By this time, I'm thinking this is may be a wind-up, and I've fallen for it. Oh well, keep going a bit more and see.


    I still don't see how spreading resin with this is gonna work.


    This is just getting rediculous!

    Then, just as I was about to give up;


    Eureka! Now I see what you're on about!

    OK, hijack over, return to normal programming.

    • Like Like x 2
  15. Ran my bike into a telegraph pole a fortnight ago (broken leg). Will take sometime before I go ahead with this plan. Thanks for the replies so far. Good news is I'll be needing new fairings unless I repay the old scratched up ones.
  16. Bugger! Hope all goes well with the healing up.
  17. This is a setback. Heal quickly.
  18. 2015-03-08 14.35.19.
    Still runs, need to replace indicators, mirrors and straighten out brake and gear shift levers. Some other cosmetic scratches. Notice the not existent damage to my helmet (thankfully).

    Now back to fairing.

    I can do this a few ways with foam.
    1) Easy Mode. Have completed foam plug made based on CAD design (do not know CAD probably expensive).

    2) Lofting. Have foam cut into cross sections of the design to be finished by me (do not know CAD probably less expensive).

    3) Sculpting. Buy a bunch of foam, stick it to my bike and cut and sand until desired shape is achieved (cheapest but labor intensive and prone to mistake/inaccurate).

  19. There might be a fourth option......

    Is your model of Honda sold, any place in the world, with some kind of fairing?

    If so, you might be able to buy a cheap and cheerful Chinese replica fairing, then with that fitted you could work on extending the existing fairing into what you really want.