Why EPO for slope glider version? - Page 4 - RC Groups
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Nov 02, 2007, 09:53 AM
nsg
nsg
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Ken - one reason to apply tape or film covering may be to help the foam handle the tensile stresses (my theory anyway :-) )
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Nov 02, 2007, 10:35 AM
Houng-wen Lin
GWS4CEO's Avatar
I saw the prodouctionline is packing the GWS F15 EPO SG version!
Nov 02, 2007, 11:05 AM
Proud member of LISF and ESL
Quote:
Originally Posted by kensp
"I have started to see EPO in other products. I have a glider called the Hawk that is made of it. However the retailers seem to be confused as they are listing it as EPP." EPO is definitely not EPP. It looks similar to Elapor but it has a greasy feel to it.

What kinds of glue work on EPO?
"Regular CA?" Yes but needs kicker.
"Epoxy?" No
"Gorilla Glue?" Yes
"White and yellow glues?" No
"Others?" GWS Glue or Polyurethane glues

"Can we use fillers with EPO to get smoother finishes? What kind?" Fillers are not needed and possibly would not stick well.

"What kind of sanding considerations? Will it sand?" Yes it sands well, but the kits need very little sanding. The surface finish is almost as good as that on the latest GWS EPS kits.

"Any special considerations for paint? Water based?" Solvent based? You can use any type of paint that will stick. Both water and solvent based will work but some paints require a primer.

"Can I apply Monokote or similar coverings to it?" I have not tried to and see no reason to.

"A common repair method with Elapor is to heat it with hot water to expand it after a hard bump. Will EPO work the same way?" I have not needed to repair yet.

Ken
Ken,

Thanks so much for the answers. I was going to do some experimentation. This will help me a great deal.

As far as sanding, I was thinking primarily about he mold marks. I have them on my Easy Glider and they are very very pronounced through the paint. I don't think they hurt the flying performance, but many people were concerned about the quality of the finish. And, if I paint one of these again, I will likely want to sand off the nubs.

Likewise from a filler point of view. To get a smooth finish, that does not show, or at least minimizes the cell structure, I was thinking a filler would be a good step. Has anyone tried fillers for this purpose?

I have used light weight spackle on wood but I think this would flex too much and just pop the spackle out.

Ed
Nov 02, 2007, 11:31 AM
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Joe 1320's Avatar
For flexible foam like EPO, EPP, Elapor, etc.... I like Liquid nails perfect glue #1. It stays semi flexible.
Nov 02, 2007, 04:54 PM
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kensp's Avatar
Quote:
Originally Posted by nsg
Ken - one reason to apply tape or film covering may be to help the foam handle the tensile stresses (my theory anyway :-) )
The EPO foam is a composite foam that appears to be EPS beads coated with another plastic. This second plastic fuses together during molding to make a honeycomb type structure with far greater tensile strength than plain EPS foam. Photo No 1 shows the cell structure of the EPO foam.

I bent the tailplane on my EPO GWS T-6 to such a degree that EPS would have broken but the EPO foam just sprang back to the original shape when the pressure was released. So nothing is needed to improve the tensile strength of the EPO foam. Maybe if you want a smooth shiny finish then plastic films, such as Monocote, could be used.

Photo No 2 shows my completed EPO GWS T-6 Slope Soarer. To build and paint this model I only made two changes to my normal technique for building GWS models. The changes were to use medium Super Glue with kicker, instead of Epoxy glue, and to paint a plastic trim primer onto the foam before the colour coating.

Ken
Last edited by kensp; Nov 02, 2007 at 07:07 PM.
Nov 02, 2007, 05:11 PM
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kensp's Avatar
Quote:
Originally Posted by Joe 1320
For flexible foam like EPO, EPP, Elapor, etc.... I like Liquid nails perfect glue #1. It stays semi flexible.
I had thought of trying liquid nails but after using medium Super Glue (as we call CA glue here in Aust) I was so pleased with the speed of the build that I did not try the liquid nails.

This is a brand new plastic foam that does not seem to be exactly the same as other foams such as EPP, Arcel or Elapor. So we will have to do some experimentation to get the best techniques for building and painting.

I plane to try Humbrol oil based enamels on my coming EPO GWS-40 build. This paint has a magnificent range of all the WWI, WWII and later colours.

I was doubtful when the EPO foam was announced but now the ease and speed of build using Super Glue has impressed me.

Ken
Last edited by kensp; Nov 02, 2007 at 07:08 PM.
Nov 05, 2007, 04:16 PM
Long to be flyin'
Antonsoarer's Avatar
Just for those who aren't aware there is also another flexible and resilient foam: PPA

https://www.rcgroups.com/forums/showthread.php?t=312112

Tony.
Nov 05, 2007, 07:51 PM
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kensp's Avatar
Quote:
Originally Posted by Antonsoarer
Just for those who aren't aware there is also another flexible and resilient foam: PPA

https://www.rcgroups.com/forums/showthread.php?t=312112

Tony.
One question. Can this PPA foam be molded to give a smooth surface that can be painted without needing to be sanded?

Ken
Nov 06, 2007, 12:04 PM
Rotozuk's Avatar
Quote:
Originally Posted by kensp
One question. Can this PPA foam be molded to give a smooth surface that can be painted without needing to be sanded?

Ken
Well, reading that thread I'd say that the answer is currently no. One company makes the PPA foam (or did make it) and they sold it in block form. It could be carved with a sharp edge or hot wired. Sounded like a clean version of EPP, but not as stiff. Looked very nice for wings in combat ships, etc.

Many EPP electric plane kits are hot wired or cut from block and have a finish quality of YUK! These planes made from PPA would sure look better.

-Wayne
Nov 06, 2007, 01:49 PM
gws-online-dealer
gws-rc-models.ch's Avatar
I got a few of the new GWS-15 - EPO kits in today.

First impression was: Wow, all the fine lines on this version are exactly the same "fineness" like on the styro version. The surface is smoother than on the Multiplex models. You can see that the foambubbles are bigger than on the styro GWS-15, but the surface is so smooth that I expect that after painting you will see none of the bubbles anymore.

And wow, you can really bend that stuff like the Multiplex stuff.

Since I already fly a styro GWS-15 with fans, I will have to build one of these as a pusher with a 28mm inrunner in a GWS 400 gearbox.

Well done GWS, I was very critic in the beginning because I thought the EPO models will come out like the Multiplex stuff (which structure I dont like to much), but it doesnt, its better....
Nov 06, 2007, 02:53 PM
Long to be flyin'
Antonsoarer's Avatar
Quote:
Originally Posted by kensp
One question. Can this PPA foam be molded to give a smooth surface that can be painted without needing to be sanded?

Ken
Ken,

I don't know if it can be molded into a complex shape, I think my supplier molds to order as he can supply any thickness I want. It is very smooth as supplied and after hot wire cuts, looks like good pink or blue closed cell EPS.

It can be used bare and just painted if the design gives enough structural integrity but without x-weave it can be ripped.

Covering it with x-weave tape gives much bigger gains in toughness than with EPP. I have hit wire fencing at very high speed and only seen minor pvc tape damage and little or no x-weave damage with no detectable damage to the foam.

Tony.
Nov 07, 2007, 09:26 AM
Houng-wen Lin
GWS4CEO's Avatar
Any one who had experienced with GWS EPO, pls tell us how you like?
Nov 07, 2007, 06:31 PM
Registered User
kensp's Avatar
Mr Lin.

I like the EPO foam because of
  • Clean molding
  • Smooth surface that does not need sanding
  • No need to tape the model
  • The use of normal Super Glue (CA) with kicker
  • Can be painted with water based, oil based paints or lacquers
  • Durability
I dislike
  • The extra weight
  • The need for priming before painting colour coats

The ability to use Super Glue (CA) with kicker is a compelling reason for me to build all of my future models from EPO Kits. Add to this the extra durability of the EPO foam and I think that the cost and weight penalties are negated.

Ken
Nov 07, 2007, 10:22 PM
Registered User
Ken,

Are you saying that GWS should produce more EPO birds ?

Chen
Nov 07, 2007, 11:44 PM
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kensp's Avatar
Quote:
Originally Posted by GWS CHEN
Ken,

Are you saying that GWS should produce more EPO birds ?

Chen
Yes Chen.

I would love to get an EPO GWS Spitfire and an EPO Me 109 to replace my four year old models.

B.T.W. I have just tested Humbrol oil based enamel paint on the EPO GWS-40. I did not use primer but the paint has adhered very well. Humbrol has a very wide range of WWI and WWII Warbird colours. It has very good coverage so I think that one or two coats of thin sprayed Humbrol will be very light.

Ken


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