Foam ribs covered with Econokote or similar? - RC Groups
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Jan 24, 2012, 02:59 PM
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Foam ribs covered with Econokote or similar?


Anyone ever build a plane the "regular way" except for using balsa ribs they used foam? Just curious for an alternative technique to covering the whole structure in foam.
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Jan 26, 2012, 10:44 AM
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No one? I guess I have some experimenting to do!
Jan 26, 2012, 11:04 AM
Winging it >
leadfeather's Avatar
Ghost bipe comes to mind
Jan 26, 2012, 11:16 AM
RIP Azarr - "Old age is not for sissies"
Azarr's Avatar
It wasn't that uncommon a building method years ago. We built a few competition fun fly planes with them. Particularly easy with a hot wire, just cut a small wing and slice off the ribs. With the advent of ARFs and foamies, most people aren't into actual building anymore.

Azarr
Jan 26, 2012, 12:28 PM
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Quote:
Originally Posted by Spamman127
Anyone ever build a plane the "regular way" except for using balsa ribs they used foam? Just curious for an alternative technique to covering the whole structure in foam.
The problem with substituting foam for balsa in a film covered open wing is that foam lacks the compressive strength of balsa. It can be done but you'll need design a proper spar and support the LE and TE so they don't warp when you shrink the covering.

The advantage, besides cost it that you can hotwire your ribs all at once. Very useful for tapered wings.

See this post: https://www.rcgroups.com/forums/show...2&postcount=75 for the "laser method" using foam ribs.

You can also just sheet from the spar forward and add balsa cap ribs and TE to use this method with heat shrink films.
Jan 26, 2012, 12:34 PM
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Toysrme's Avatar
you can, all tho it can lead to extremely floppy models more prone to damage than just building with balsa & sheeting that.



more popular is to not cover, but use only a minimum amount of foam ribs, spars & bulkheads and sheet it with foam.

also, cheaper than wasting good covering or copious amounts of tape on foam is to take paper & use watered down PVA/AR (white glue or wood glue) and paint that on. it's lighter than tape & adds a huge amount of strength & rigidity to the foam. i have a 3 channel balsa trainer with a styrofoam wing constructed in that method. it's 18 years old, still flies & has taught no telling how many people to fly.

plus, then you can use regular old spray paint without fear of the harsh cleaners & accelerators eating foam





there is no right or wrong way to build something.
Jan 26, 2012, 05:59 PM
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I know this build: http://www.wherzog.de/eflug/sukhoibau1.htm

All in german but you can see by the pics that they used foam ribs on thae wing.
At the bottom of the page you can click further through the build.
What they used for building is a foam called "Styrodur". This is quite dense an "hard" foam.
Jan 27, 2012, 12:59 AM
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AsSoulsDream's Avatar
I've seen it done with the plastic heat shrink that they put around fruit gift baskets, and you can get it at the Dollar Store just spray the foam with 3m 77 or I prefer 3m 90. That will get it to stick to the foam then just use a hot hair dryer or low temp heat gun, you can use a heat gun if its too hot just pull it away from the plane a little farther
Jan 27, 2012, 01:29 AM
Up-Out-&-Gone
demondriver's Avatar
The covering you choose is also VERY important I find Ultracote & Towercote to be best direct to foam, just be shure if you use a Heat-gun to stetch out any loose covering not to melt the internal foam structure, I use Monocote & ultracote on all my airliner & Bomber builds, Good luck Spamman!
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Jan 27, 2012, 01:31 AM
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larryross's Avatar
Do you have a brand name or product name to identify the right plastic?



Quote:
Originally Posted by AsSoulsDream
I've seen it done with the plastic heat shrink that they put around fruit gift baskets, and you can get it at the Dollar Store just spray the foam with 3m 77 or I prefer 3m 90. That will get it to stick to the foam then just use a hot hair dryer or low temp heat gun, you can use a heat gun if its too hot just pull it away from the plane a little farther
Jan 27, 2012, 01:53 AM
'scuse me while I kiss the sky
Lafayette's Avatar
Quote:
Originally Posted by larryross
Do you have a brand name or product name to identify the right plastic?
https://www.rcgroups.com/forums/show....php?t=1243116
Jan 30, 2012, 12:15 AM
Registered User
Thanks for the replies guys! I think I will incorporate this style of construction in my next build. Another question. What would you guys use to glue the balsa to foam? I'm thinking white glue, any other suggestions?
Jan 30, 2012, 12:31 AM
'scuse me while I kiss the sky
Lafayette's Avatar
Quote:
Originally Posted by Spamman127
Thanks for the replies guys! I think I will incorporate this style of construction in my next build. Another question. What would you guys use to glue the balsa to foam? I'm thinking white glue, any other suggestions?
BEST BET:FOAM SAFE CA
3M77
Gorilla glue(need to clamp tight as it will expand 3x)
OR:
My ex mother in law's turkey gravy!


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