Colin I was avoiding extruded polystyrene since I couldn't find it here in Southern California but since you brought it up again I have found that it is available near here (near French Valley) in Temecula at Whitecaps: http://www.whitecap.com/shop/wc/building-materials/insulation-materials/extruded-polystyrene-insulation so if anyone else here in SoCal needs it it does exist!! Thanks Colin and best on your trip over the Bearing Straits and beyond :) BillM
> To: krnet at list.krnet.org > Date: Sat, 22 Aug 2015 23:23:19 +0100 > Subject: KR> Foam, peel ply and tank vents... > From: krnet at list.krnet.org > CC: colinhales at hotmail.com > > Several thoughts gents, > Bill, high there, I'll write soon, but continuing, unless you want to use > wing tanks, remember that Styrofoam is a much better product than Urethane > foam which I would NEVER ever use. > It crushes and has no rebound unlike polystyrene foams, so if you drop > something on your wing skin or someone kneels on it, the Urethane foam > crushes and a void is left behind the glass as it pulls away from the glass > skin. Styrofoam has a bit of bounce and give and this doesn't happen. Also > Urethane is open cell and you have to add the heavy layer of Micro balloon > slurry to seal it before adding the glass cloth and trying to wet it out. > If you want to still use Urethane foam, you can now get a closed cell type. > Any open cell foam can and will absorb water over time and you never know > about it. Even white polystyrene foam is not water tight enough and water > gets between the molecules over time, unless it is well sealed. > So personally open cell Urethane foam is just a bad idea all round. > I've squeezed water out of Urethane foam on a hovercraft, if you get water on > your plane with open Urethane foam, it goes in and you will never get it back > out. > If you want to use stub wing tanks, and have the outer panels dry, then by > all means use Urethane foam for the stub wings but use Styrofoam for the > outer wing panels. > Here is an article of other types of Styrofoam. The don't like the standard > blue foam much but they are hot wiring it. We are not. > https://www.flyingfoam.com/content/why-we-hate-blue-foam > > A typical good supplier of blue foam I would say is, > http://building.dow.com/en-us/products/styrofoam-brand-residing-board-us-only/?sc_itemid=320ebb4f-f0ab-47e7-a5b6-334429f8dec8 > Next, peel ply. > A good cheap source of peel ply is called 'Ceconite', you know the stuff they > stick on fabric aircraft? Go grab a load of off cuts from a fabric shop or > buy some, its as good as the peel ply you can buy, no silicones obviously, > and it comes in 6 foot wide strips in case you want to cover large areas. It > comes in different grades of light or heavy that will give you different > surface textures depending if you want to add on to the glass or simply have > a smooth surface ready for applying fillers and top coat paints. > Fuel, > As for fuel sitting in vent pipes. If you can see the fuel sits in the pipe > or presume it would do in the dip, that is fine . The air will bypass the > fuel so don't worry about that, there is 'little' to 'no' head of pressure in > the pipe, any slight difference in pressure will move the fuel along. My only > comment on this is that you better make sure the vent pipe you are using or > going to use is happy to have avgas or mogas or regular gasoline, whatever > you intend to use sitting in it for long periods of time. Some nylon pipes go > brittle when immersed in fuel for long periods. Just food for thought. > Sorry I'm going to miss the Kr gathering, I went through Mc.Minnville a week > or two ago on my way up to Alaska. It is a brill place to visit, town is > lovely, the puce Goose and the rest of the Museum is top rate and Graham, > Northwest Air Repair is a great host, so please pass on my regards. > I'm now in Anchorage, eyeing up the Russians and seeing what can be done to > continue. > Cheers Colin. > _______________________________________________ > Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. > To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org > please see other KRnet info at http://www.krnet.org/info.html > see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change > options
