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-   -   Blue foam (http://www.rcuniverse.com/forum/scratch-building-aircraft-design-3d-cad-174/49726-blue-foam.html)

rcsheriff-RCU 02-07-2002 10:45 PM

Blue foam
what is the proper name of the blue foam used in scratch building,the type that is flexible and sold in carpet or flooring stores. ALSO does anyone know where to find plans for using this foam, or plans for the wal mart type of foam glider also...
PLEASE HELP !!!!!!!!!

wynterhwk 02-08-2002 01:57 PM

Blue foam
The web site for the Walmart type planes (aka Wally Wonder Wing) is: http://www.acesim.com/rc/wallywing.html



lnjfarms 02-09-2002 06:56 PM

blue foam
Don't know about the foam in carpet stores but the blue foam from the lumber company is called dow grey board. It can be found as thick as 2" and is extruded foam very dense but light. I use it like balsa for fuse and wings.
The dow foam can be sanded without damage and wire cuts very well. (I use a feather cut machine).
Have built a fokker D8 and am working on another one all built from the blue dow foam

highflyer353535 02-26-2002 09:42 AM

Blue foam
hi.. injfarms is the blue foam better than the pink foam? i am getting ready to build a 1/4 scale c-130 lockheed hercules...that is done with foam then sheeted

Mike James 02-26-2002 09:54 AM

If I'm not mistaken, typically white styrofoam is 2lb/sq.ft., blue foam is 4lbs/sq ft., and pink is 6 lbs/sq.ft.

Pink is too heavy for most flying models, but is great for making plugs. I never use anything but white foam now for flying parts, but have made a few (heavy) blue foam wings in the past. (sheeted)

lnjfarms 02-26-2002 07:26 PM

Blue foam
just for fun I weighed some of the foam that I have been using here. White foam is not available from any of the local suppliers so I was unable to weigh it but here is what I came up with
dow grayboard (blue foam) weighs .0141 ounces/cubic inch.
pink foam (owens corning extruded) weighs .0143 ounces/cubic inch. Just for a comparison I weighed some balsa here off the shelf and it weighs .1088 ounces /cubic inch
That boils down to a 4ftx8ft sheet of blue foam 1.5 inches thick will weigh about 6 lbs the same size chunck of balsa would weigh about 47 lbs

Ollie 02-26-2002 10:17 PM

Foam Density
Corning, pink foam, comes in a variety of densities and compression strengths as Foamular 150, -250 and -350. Foamular 150 is similar to Dow grey board in density.

Dow, blue foam, also comes in a variety of densities and compression strengths. The Dow Hi-Load series (45, 60, etc.) features elongated cells that produce greatest compression strength in the direction perpendicular to the plane of the panel.

Which densities are available locally depends on what the building trades are using locally.

highflyer353535 02-26-2002 10:39 PM

hi..ollie.. i am getting ready to scratch build from a set of plans..a C130 HERCULES LOCKHEED 1/4 SCALE THE CONSTRUCTION is of foam.. which it does not specify other than polystyrene.. then sheeted.. i was just wondering .. our home depot here sells the pink board which seems vert sturdy and light.. any recomendations which foam or is it personal preference.. i am not really concerened about weight since this monster is going to have 4 powerhouses.. any suggestions? would be appreciated thank you

Ollie 02-27-2002 02:14 AM

A 1/4 scale C130 will have a wing span of 33.15 feet. The tip of the tail will be over 9.5 feet off the ground. That is bigger than some light planes. Planes that size should be inspected and certified under FAA rules because of safety considerations.

Safety considerations aside. It will probably take four good size dirt bike engines or equivalent to get it off the ground. It would weight less than 250 pounds to put it in the ultra lite category. If you could build it in the ultra lite category you would still have to fly it yourself. I wouldnít fly anything that hadnít had the proper enginering calculations for strength, etc. I doubt very seriously that you could buy servos in the local hobby shop strong enough to operate the controls. I donít think your project would be covered by AMA insurance.

The Experimental Aircraft Association could give you the best advise.

In summary, it is way too soon to be selecting foam.

Tom-RCU 02-27-2002 08:23 PM

Blue foam, pink foam and balsa

In this thread folks have been asking about different foam densities. I thought the following summary may help in the discussion:

As Ollie pointed out "Blue foam" == Dow HiLoad, "Pink foam" == Corning Foamular. The following tables list products, strengths and densities of the commonly used (by modelers) foam products. Note the compressive strength for some products varies by axis.

From a CASA 3/99 newsletter we have the following "Blue Foam" data. (sorry for the poor formatting, I am attempting to attach the formatted newsletter as PDF)

Type Compressive Strength Compressive Modulus
Flexural Strength Density

FOAMULAR 150 15 psi min. N/A
60 psi min. 1.4 pounds/cubic foot (approx.)
FOAMULAR 250 25 psi min. N/A
75 psi min. 1.8 pounds/cubic foot (approx.)
FOAMULAR 400 40 psi min. 1400 psi min.
115 psi min. 2.04 pounds/cubic
foot (avg.)
FOAMULAR 600 60 psi min. 2200 psi min.
140 psi min. 2.4 pounds/cubic foot

Type Compression Strength Minimum Density

High Load 40 40 psi min. 1.8 pounds/cubic foot
High Load 60 60 psi min. 2.2 pounds/cubic foot
Grayboard 15 psi min. 1.35 pounds/cubic foot

From my limited experience with High Load 60, the above density for seems low, and I might better agree with the following data found in the same article:

Type Weight Compression Strength
High Load 60 2.8 pounds/cubic foot 60x60x60 psi
Spyder foam 2.3 pounds/cubic foot 45x15x15 psi
Interesting to note the better three dimensional properties of High Load vs. Spyder foam.

White expanded polystyrene is available in several densities and strengths. Type I is 1 pounds/cubic foot @ 10 psi. Type II is 1.5 pounds/cubic foot @ 15 psi. Type IX is 2.0 pounds/cubic foot @ 25 psi.

I hope lnjfarms doesn't mind that I point of the widely varying density of balsa and that he measured a piece that might be found in the typical local hobby shop. Contest grade balsa is about 6lbs per cubic foot.


lnjfarms 02-27-2002 11:48 PM

balsa weight
Hey Tom,
no problem I fully admit that the piece I weighed was a common run hunk of balsa from an outfit in Texas that cuts their own. To be honest I am not up on how balsa is graded and just what does constitute competition grade. There are several pieces in the last batch that are very hard and some that are very soft and not good for anything but sheeting. I have a couple of pieces that are an off color as well very dark .
Let me know about the pdf file on foam though I would like to see the info. I believe that the local lumber yards can order any type of foam I need. Again the pieces that I weighed are what was left over in the shop from cutting out a Fokker D VIII and a set of wings for the flapjack in the Microflight article this month.
The Fokker fly's very well and a bit fast but I need advice on putting landing gear on a foam fuse. So far all attempts have been to frail. Tried using dowels glued into the foam endwise and drilled to accept the wire. Did not work first hard landing pushed the dowels through the foam.
Anyone have any Ideas???????

lnjfarms 02-28-2002 12:19 AM

1 Attachment(s)
I guess I should put a pic of the DVIII up here as well. The specs are as follows:
construction is all blue foam with brown paper covering
flys with a Gropner 480 race and a Model Air Tech 2.56:1 h100 beltdrive on 8 2/3 ae cells

Ed Smith 02-28-2002 01:35 AM

Blue foam
I love the rustic backyard, complete with chickens. Nice touch!

Ed S

lnjfarms 02-28-2002 05:58 AM

Hey Ed,
Guess I had not paid any attention to the backround in this picture, it was taken to send my dad he fly's RC as well. As you can see this is a farm and we do raise chickens for eggs. The tires in front of the tree are part of a pile of engines and trans axles for VW's ( I run sandrail dune buggys).
The lumber is cut offs and leftovers from the sawmill which is in the barn that can be seen in the picture. My outside test and painting bench is of course a dead freezer.


paperairplanes 03-03-2002 04:12 AM

Blue foam
so would pink foam be good to use for wings? how about pink foam for wings on a jet? turbine? i hate to order the white foam known as epp or eps if I could only find some in my area.

lnjfarms 03-03-2002 05:15 PM

Blue foam
Hi Paper,
I think it would work ok it depends on the design criteria, weight , size, power, etc etc. As you can see from the above posts there are different weights and strengths involved. When I needed some epp foam for a skin on a flying wing I went to my friendly neighborhood Wal Mart. They sell foamboard which is epp foam .25 in. thick with paper glued on both sides. My project was electric so the paper added to much weight. An overnight soak in warm soapy water made removal of the paper easy and I had two sheets of epp foam for upper and lower skins for the wing

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