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What is the best material to use for molding for a RC hydro. What are some other materials I should get thanks for looking.
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Boron fibre with Polyetheretherketone (PEEK) as the binder would be "best" but will not be practical for the vast majority, due to both the extreme price of boron fibre (which also makes it hard to source, since carbon stiffness isn't that much worse but it is many times cheaper nearly everyone switched to using it/selling it), and moulding with PEEK is very hard for a small run manufacturer as it is naturally a solid and needs to be heated to 400C for moulding, which due to the temperature is best done by injection into a metal mould.
Broadly speaking the tensile strengths of all the fibres are similar, what differs is the amount they will stretch before breaking, with Aramid (kevlar) scoring highly, and Young's modulus (stiffness), with glass being worst, Aramid being aorund 50% stiffer than glass, carbon being around twice as stiff as Aramid and Boron being around 20% stiffer than Carbon.
For the practicalities of home moulding on a budget, if you have access to or can make a vaccum bagger then carbon is the best, if not then its a PITA to get it to lay into all the corners well and I wouldn't make a whole hull from it, just use it to reinforce and stiffen the large flat areas, it's also worth considering that if you have any carbon on the sides or top of the boat you will need to run an external aerial for the radio. Glass and Kevlar are much easier to lay up, Aramid is a PITA to cut but it can be done with either specialist sheers, or sharp razor blades and a lot of perseverance/patience. Let you budget decide which to use Aramid is better but MUCH more expensive. I have used a mixed carbon/aramid weave in the past for aeroplane fusalages and I have to say that I do not think it is a good material, after a crash the Carbon strands would be fractured but the Aramid was elastic enough to survive which leaves a convenient bag to take the bits home in but its no longer stiff enough for use, whereas if I had made it out of just Carbon for the same stiffness I could have made it lighter and had better performance untill the crash that would still have killed it, and if I made it from just Aramid, it would have had to be heavier to maintain the stiffness, but would have survived the crashes and been fine to fly again. I do still use it for bottom reinforcement but just because it looks good and I have a bunch already so it costs nothing, It's the worst compromise possible IMO being hard to cut and hard to lay, costing the same as carbon but not being as stiff, having the elasticity of Aramid but if you use it you break the carbon and loose 2/3rds of the stiffness it had.
Pretty much without question Epoxy resin is the most suitable binder for our fibres, the other easy to use binders (polyester and vinylester) pretty much only have their price going in their favour and you wont be using enough to make 1 model boat hull that it will make a massive price difference anyway. Epoxy has less mold shrinkage, better adhesion and better solvent resistance than Polyester or Vinylester and has better flexibility and fracture toughness than Polyester.Paul Upton-Taylor, Greased Weasel Racing. -
Thank you for all the informationComment
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