As Larry said, male moulding almost always results in a lot of fairing to cover wrinkles, overlaps and extra laminate. Much better to use female moulds. Problem with these is joining the halves. Etamax uses closed moulds, but these are not for the faint hearted or the novice.
Best solution is moulds for the front and rear sections and make the join at the max chord. This area is less critical shape wise than the leading and trailling edges and much easier to join. Also makes it easier to install a sheer web if required. Moulds can be hot wire cut foam (check the straightness of the edges. 2' sections are likely to be straighter than 8', unless they are cut with a rotating wire) or multiple pieces of mdf, which allows you to vac bag in the mould. Plastic sheet on the mould saves a lot of finishing and polishing.
Best solution is moulds for the front and rear sections and make the join at the max chord. This area is less critical shape wise than the leading and trailling edges and much easier to join. Also makes it easier to install a sheer web if required. Moulds can be hot wire cut foam (check the straightness of the edges. 2' sections are likely to be straighter than 8', unless they are cut with a rotating wire) or multiple pieces of mdf, which allows you to vac bag in the mould. Plastic sheet on the mould saves a lot of finishing and polishing.
Doing anything to partially cured laminates is rarely a good idea. Especially bagged ones where it is hard to know the state of cure.
On Sun, Nov 8, 2015 at 3:20 AM, Gardner Pomper gardner@networknow.org [harryproa] <harryproa@yahoogroups.com.au> wrote:
I have been thinking about wing masts again, and had some ideas on how to build them. Since I have no real experience doing so, I was hoping to get some feedback on whether the ideas make any sense.First, get blue foam, or something similar, CNC cut (in sections that fit together, if necessary) for the length of the mast.Cover with 1 layer of light fiberglass, with wax paper covering the mandrel and overlap, so the fiberglass does not stick to the mandrel or itself. After if cures, glue the overlap together, but not so tightly that the mandrel cannot be removed.Using this fiberglass as a base, lay up the carbon fiber, etc and infuse it to build the mast, using the inner fiberglass skin as the "table", so there is no vacuum force on the mandrel. Once it is done, the foam mandrel can be removed and used to make a second mast.Another idea for building a wing mast is that you can put the bearing up inside it and have a stub mast that buries in the hull that does not need to rotate. The bearing only has to fit up inside the wing mast for about 4' or so (the same bury calculated for the hull). Also, I don't see any reason it needs to be permanently affixed. Couldn't it be in a removable tube, so that it can be replaced if it wears out? All it is doing is allowing rotation.Feedback is welcome, and is, in fact, the whole point of this post.- Gardner
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Posted by: Rob Denney <harryproa@gmail.com>
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