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Thread: blue foam board plane bulding

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    blue foam board plane bulding

    does any one have any photos to post here on building planes with the blue foam board ? im interested in detailed wing designed from ultralight to acrobatic and if its acrobatic please note it. also glue types,board thickness,fuselages welcomed also.inventors to.

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    Registered User GESchwarz's Avatar
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    Re: blue foam board plane bulding

    If I understand you right this blue foam is the common foam used as thermal insulation in the construction industry, and is used to build RC models?
    Last edited by GESchwarz; August 15th, 2010 at 06:18 PM.
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    Registered User steveair2's Avatar
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    Re: blue foam board plane bulding

    Commonly called blue dow. It is not used much in aircraft construction.
    There are a few. www.flysquirrel.net and www.beaujonaircraft.com

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    Registered User bradyaero's Avatar
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    Re: blue foam board plane bulding

    Quote Originally Posted by steveair2 View Post
    Commonly called blue dow. It is not used much in aircraft construction.
    There are a few. www.flysquirrel.net and www.beaujonaircraft.com
    it's been used in a few no-name planes like long-ez, vari-ez etc....
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    Registered User wsimpso1's Avatar
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    Re: blue foam board plane bulding

    Cozy, Aerocanard, and others.

    The Rutan ships and their derivatives have their wings, canards, winglets, and control surfaces carved out of the stuff. Fuselages of same ships have other cores.

    The plans specified Dow flotation billet, which is styrene foam. The boards for building insulation are slightly different stuff, but still styrene foam. The stuff has this terrific advantage for making flight surfaces - you can safely hot wire some pretty darned accurate airfoils that way.

    On my bird, vertical and horizontal tails and all control surfaces are flotation billet.

    Billski

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    Re: blue foam board plane bulding

    the flysquirrel had some very good detail wing foam design that i can improve on; but i"m still open on more designs, thanks allot !

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    Registered User Dan Thomas's Avatar
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    Re: blue foam board plane bulding

    In the '70s Ken Rand created his KR-1 using a set of Taylor Monoplane plans. Instead of cutting all those hundreds of little pieces for the ribs he just cut a few from plywood and used them as patterns to sand styrofoam to shape between them. He used foam instead of plywood on the fuselage, IIRC, and in the tail too. Covered it all with polyester fabric and epoxy resin. Polyester fabric is lighter than glass but stretches a lot more, too. Same fabric as used on fabric-covered airplanes.

    Trouble with all that is the cost of epoxy. You can't use polyester resin (fiberglassing resin) on styrofoam; it'll dissolve the foam. If you want to use polyester resins you have to use urethane foams, which cost a lot more than styrene foams. Gasoline will eat styrofoam but won't touch urethane foam. One of the more common tricks was in making gas tanks; cut and sand the tank shape from styrofoam, glass it up with either polyester fabric or glass cloth, and epoxy resin, then chop the filler hole out of the top, pour in gasoline to dissolve the foam and dump it out. Rinse and repeat as necessary. Epoxy in a filler neck for a cap and a fitting on the bottom for the outlet.

    This sort of construction was supposed to revolutionize homebuilding and production aircraft, but we still see a lot of conventional construction from both homebuilders and the factories. The composites have their drawbacks, too, and some of those airplanes are awful heavy, like our Cirrus SR20, way heavier than a 182. Looking into the structure it becomes apparent as to why: few wing ribs, so the skins have to be pretty thick to carry the unsupported areas. Simplicity is often heavy, something I found out years ago building a frameless boat of my own design. Easy to build and almost impossible to move.

    Dan

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    Re: blue foam board plane bulding

    I am surprised no one has mentioned the Sky pup.

    Home Sky Pup

    There are several other sites with this airplane. Also, several Youtube videos for the Sky pup.

    Kevin in Missouri.

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    Re: blue foam board plane bulding

    I was going to mention the Skypup as well, though its not used structurally, just to fill in the gaps between the structure.

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    Re: blue foam board plane bulding

    Not used structurally?!! You must not have Sky Pup plans. Look at the spar and the ribs. Look at the uprights that hold the wing to the fuselage. To me that is very structural.

    Kevin in Missouri

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    Re: blue foam board plane bulding

    The generic name is extruded polystyrene. The most common is Dow Roofmate, Wallmate and Floormate, all colored blue. I have built a gyroplane all flying cruciform tail using it and tested it to 30 lbs/sq ft loading X 2 safety factor. Read more at STYROFOAMâ„¢ Brand ROOFMATEâ„¢ Insulation.

    And also take the Min. compresssive strength of 40 psi listed with a grain of salt. As bilski mentioned there are many grades of stuff. I assumed 20 psi compressive strength.

    It is not heat resistant and will start losing its strength at temperatures a dark colored surface could reach in direct sunlight much like epoxies with low glass transition temperatures. It is also not fuel resistant.


    Dino

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    Registered User GlassVampire's Avatar
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    Re: blue foam board plane bulding

    Well then I stand corrected. Is it just..plain foam? Epoxy? Anything??!

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    Re: blue foam board plane bulding

    actually it is structural, it is the shear web for the spars and the shear panels for the fuselage. The design shear allowable that Steve used was 15 psi. The foam reliabaly failed around 90 psi, in testing, but the derated allowable was considered a good safety margin

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    Re: blue foam board plane bulding

    And you need to watch what foam you use. There is some insulation stuff in Home Desperate and other 'big box' home-improvement stores that is blue, comes in sheets, and otherwise resembles on casual observation the stuff we're talking about here.

    IT'S NOT THE SAME, AND IS NOT SAFE FOR AIRPLANE USE.

    The cheap stuff you can get at Home Depot and the like doesn't have much strength at all, and is far too flexible. It tends to crumble at a very low load, while the good stuff takes a pretty amazing load and then fractures.

    How can you tell the difference?
    • The 'bad' stuff looks like it's made of a bunch of foam beads pressed together until they're one solid block. You can't really see individual 'cells' in the foam, except as a kind of 'sparkle' in the areas inside the 'bead boundaries'. It looks exactly like a blue version of the stuff used to make cheap camp/sports coolers - becuase that's exactly what it is.
    • The GOOD stuff looks like a fine foam sponge. You can see distinct open cells in the foam, just like a sponge, only smaller. It has a rough surface along a cut edge, because of these cells, and it's one smooth composition, without any of the 'pressed-together-beads' appearance of the cheap stuff.
    Another way to tell: If you can bend the sheet much at all without feeling like you might break it (it's somewhat flexible) at thicknesses any greater than about 3/4", you've got the wrong stuff.

    I have yet to see the 'good' material sold at a 'big box' home-improvement stores in my area. They invariably carry the cheaper, compressed bead foam, which is absolutely useless for airplane construction. If you want to be sure, buy your foam from Aircraft Spruce or Wicks. They'll give you the right stuff. Isn't cheap, but neither is your life.
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    Rom
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    Re: blue foam board plane bulding

    The blue or pink extruded foam used in construction, not the bead board, and that can be found at home centers, is 1.5 lb/cf density. Currently building a school out of the stuff in the form of insulated concrete forms (ICF) at 1.5 lb/cf. Very strong material to hold an 8' height of poured concrete.
    The blue foam sold at Aircraft Spruce is 2 lb/cf. My control surfaces are made of the 2 lb veriety.
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