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Old Mar 19, 2008, 08:45 PM
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Foam Types

Got a couple foam questions for you RC Guru's. I see people referring to "EPP" foam around here. Is this type of foam special or unique for RC planes? Is EPP foam what the average RTF plane is made of? Is it just the same stuff that beach coolers etc., are made of?Are there better (stronger) types available that would be suitable for this hobby? I assume the sheets of "Styrofaom" that you can get at Lowes and Home Depot are not suitable for our needs? Geez...so many questions huh!

I ask only because we use "Foam Core" at work and now that I am into RC Planes they are happy to give me all the free scraps I want. The sizes they can't use any more are more than large enough to get several sets of complete tail sections and rear horizontal stabilizers (elevators). I have made a couple sets of each and tried them on my SkyFly (it's just like a Wing Dragon 3) and they seem to work fine but have noticed that they are almost half again as heavy as the original. I assume this is from the "coating" that is on both sides of the foam core. What I'm wondering is if the foam (in the foam core) is the same as this EPP stuff? Anyone know? Thanks.

Oh...and if I do want to just get some EPP foam so it's closer to the weight of the stock parts is it very expensive and readably available?
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Old Mar 19, 2008, 09:20 PM
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EPP is not the stuff coolers are made of. That would be EPS.

EPP is wonderful in that it bends and is pretty tough to break. Zagis are made of EPP. Foamies like GWS e-starters are usually made of EPP foam.
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Old Mar 19, 2008, 09:52 PM
Pushin' the Limits
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Thanks Laggard. Is this stuff usually available at most hobby Shops?
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Old Mar 19, 2008, 09:57 PM
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Quote:
Originally Posted by Laggard
EPP is not the stuff coolers are made of. That would be EPS.

EPP is wonderful in that it bends and is pretty tough to break. Zagis are made of EPP. Foamies like GWS e-starters are usually made of EPP foam.
^not EPP

EPP is a rubbery type foam. When you push your finger hard into it, it springs back to shape. EPS and styrofoam types won't. Multiplex and the Stryker, Super Cub foam are somewhere inbetween EPP and styrofoam.

The E-starter is styrofoam and GWS may be making it soon out of a better foam, but I haven't seen one yet. Some of the GWS planes are going to better foam, but its heavier.
Molded EPP, like many of the AirHog and 2ch toy planes, the WildWing and Windrider planes and the Nemo is tuffer than the cut EPP planes, but more expensive to do. Butch
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Old Mar 19, 2008, 11:28 PM
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Argh. I think you are confusing EPP with EPE.

EPE springs back; EPP not as much so or as easily but close. GWS is rumored to be releasing the new Beaver in EPE.
EPS = styro coolers (Eskies for the Aussies in the crowd). Used in GWS and other cheap planes.
EPP = Lots of the Airhogs planes as you say, and very durable. Available molded or cut sheet (Nemo)
Arcel/Elapor/Z-Foam are EPE and EPS blends. Rigidity and survivability.

Oh yeah, XPS (extruded polystyrene) is Depron. There are some other specialty foams but you almost never see them in COTS planes.
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Old Mar 20, 2008, 12:06 AM
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Ok, now I'm gettin' confused. All I really want to know is what kind is best for, or what are people using currently when making their own replacement rudders and Horizontal Stabilizers for like the HZ Super Cub? I see people posting pics and how to's from time to time on mods they are doing (making larger control surfaces etc.) on their park flyers (specifically on things like the Super Cub). Thanks
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Old Mar 20, 2008, 12:12 AM
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The best replacement is Arcel/Elapor. Or EPP if reinforced with carbon. EPP sheet is too bendy.
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Old Mar 20, 2008, 01:48 AM
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[QUOTE=IPFlyer]Argh. I think you are confusing EPP with EPE.

EPE springs back; EPP not as much so or as easily but close. GWS is rumored to be releasing the new Beaver in EPE.

It is true EPE springs back, as well as EPP. EPP is made in several different grades/weights.
I've got over 50 EPP planes and around 20 cu ft of different EPP block foam in different grades.
The lighter EPP springs back very well, with no trace.


Depron is one of the better foams for making tails. I used it on my SuperCub to lighten the tail, because I put a lot lighter motor in it.

http://www.rcgroups.com/forums/showthread.php?t=830383

I would not recomend Elapor in thin sheets like Depron for tail surfaces, unless its molded. I have several bulk blocks of Elapor and have cut off sheets experimenting with it for tails and ailerons. Any thinner than 1/4' or so and it is not very rigid. If you bend it and let go, it does not go back to its original shape like EPP will.
EPP will need to be carbonfiber reinforced in thin sheets, so Depron would be a better choice. I usually use EPP for the vertical and horizontal stabs with CF reinforcement and Depron for the elevator and rudder. Many of my EPP planes came this way. Butch
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Old Mar 24, 2008, 05:54 AM
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OK, let me add my comments:

EPS - brand name Styrofoam - Common foam airplane material, coffee cups, coolers - very light. When it breaks it breaks in big chunks and typically fixed with epoxy, white or yellow glue or foam safe CA. Regular CA melts this stuff.

EPP - common on slope gliders as it is nearly impossible to break it and stands up well to hard landing conditions. Problem is it is very rubbery so you need to reinforce/stiffen it with carbon or wood rods to help it hold shape.

Depron - That sheet foam used for meat trays at the grocery store. Very common on small flat sheet 3D planes. Popular for tail surfaces is larger planes. May need carbon or wood dowel stiffeners.

Elapor - Brand name product of Multiplex. Stiffer than EPP but more damage resistant than EPS.

EPO - Expanded Poly Olefin - becoming more popular in planes. Similar to elapor in character. This is the foam that GWS is starting to use in its newer planes.

Z-foam - Similar to Elapor - F27 Stryers and Typhoons are made of this foam.
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Old Mar 24, 2008, 10:19 AM
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Slight clarification: Styrofoam, Elapor, Depron and Z-FOam are all trademark names for various chemicals. EPS, EPE/EPS, XPS and EPE/EPS respectively are the foam types. Arcel is like Elapor and Z-Foam in that it is a blended foam.

And to the OP - as Ed suggests, meat tray foam is a great replacement for tail surfaces. Price is right (free!)
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Old Mar 24, 2008, 01:35 PM
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Ed, where does fan-fold foam (commonly called Bluecore) fall in you list?

Bill
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Old Mar 24, 2008, 01:46 PM
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I believe bluecore is EPS type foam. EPS, as do the others, comes in different densities. There is also pink core which I think is also a different density.

Not sure of the details.
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Old Mar 24, 2008, 02:15 PM
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I found this: What is "Fan-Fold Foam"? Don't know if it will be any help or not.

Bill
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