Need some help

[goslow]

Where can I get a some advice on fiberglassing ???

I have received my plans, and have enough reference material to start building the D.J. version of the SSW D III in 1/4 scale. I would like to begin with attenpting to make the cowl and spinner but having never used F.G am a little timid to begin with. I would like to use foam sheet bonded togather with a dowl (broomstick) centered thru same, put on a wood turning lathe (local buddy) and turn down to the correct O.D. and length.

What material do you seal the foam with now ?? Once sealed and sanded down to final dimentional shape, I assume you apply strips of glassing over this and use (some sort of chemical) to eat out the internal foam. Is this MEK ??? I am really in the dark and could use some good advise.

Please help

goslow

[Hannover]

I have used the "lost foam" method for cowls and other parts before, and it works very well. You should make your foam plug slightly undersize to allow for the layers of glass cloth. I would use West Systems epoxy (from Aircraft Spruce) and lay-up using a couple layers of 6 oz. glass cloth, sanding down after the first layer cures (overnight), and then lay-up the second layer. The foam can be dissolved out using laquer thinner.

Jim

[brinesharks]

Epoxy is the best resin to use as it's the least toxic and won't damage foam. Use a fairly light glass cloth (maybe 2oz). Cut it into pieces that will fit the surface contours. Glass cloth won't go around tight bends at all. Mix equal parts of the epoxy (follow directions on pots), thoroughly stirring it. Then 'wet out' the cloth with epoxy. There should be no 'white' spots or areas that aren't wet. You can make the epoxy run a little better if you warm it very carefully with a hair dryer. Be aware though that mixing epoxy in a narrow container (like a plastic cup) can produce a lot of heat due to the chemical reaction. If the container becomes uncomfortably warm, dump it in some water to prevent combustion.

Once the cloth is wetted out, a handy trick is to wrap it in 'cling film' (thin plastic sandwich wrap). Wrap it very tightly and you get a reasonably smooth finish that is easier to fill and finish. This is a cheap alternative to vacuum bagging. Once dry, fill with a light weight model filler and then sand smooth. Carve out or 'melt' out the foam with thinners. Paint in your preferred way.

'Aircraft Workshop: learn to make models that fly' by Kevin Shacklock (Nexus publications) gives very good guidance on the above technique. Well worth a read.

[brinesharks]

Kevin Shacklock gives a good account of making spinners and symmetrical/circular cowls using a clever method. He makes a female mould using auto body filler or plaster and lays up the glass inside. If you can't find his book, email me (or PM) and I'll see if I can organise some diagrams. His technique will produce a very good spinner or cowl and save you a whole lot of cursing, swearing and sanding!

[goslow]

Many thanks for the tips.....

I am waiting for some better weather as think a rainy day is not the best time to attempt this. I will try to find a good book to try and follow. Is there a rule of thumb with relation to spinner wall thickness ? Centrifugal force must be severe on the base of larger spinners and was wondering if carbon fiber should be included in the basic fiber glass mix ?

With spinners, is it best to slightly grind heavy sides or add weights(in epoxy) i.e. shotgun pellets, to achieve proper balance ?

goslow