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Old Nov 23, 2009, 04:25 PM
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Spyder Foam VS Hi-load 60/Foamular 600

Has anyone used both Spyder Foam and the equivalent Dow/Owens product?

Blue Spyder is listed as roughly 2.3 lb/cu' as opposed to roughly 2.4 for Hi-load 60 or Foamular 600.

All are said to be 60-PSI foams.

Does Spyder offer any advantages to those out there that have used it? Better hotwiring properties? Any noticeable difference stiffness wise? Pretty much the same stuff?

I did a search and came up with some questions about the bonding qualities of Spyder vs. construction foams but that is about it. CST has some on sale and I was thinking of trying it, but if someone else has done the research I would love to hear the results.
~Jim
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Old Nov 23, 2009, 04:50 PM
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Palo alto CA
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Spyder has been reported as having a higher PSI rating if I am not mistaken (false, apparently they are the same). Of course that is force parallel to the grain.

I really want to get some spyder because it is white. With glassed wings it would be easier to paint over. Your planes always have beautiful graphics, so maybe that would be a plus for you too?
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Old Nov 23, 2009, 05:05 PM
"...certainty is absurd."
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Attached, from Phil Barnes and Mark Drela:

Kevin
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Old Nov 23, 2009, 08:09 PM
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I've used all three foam types extensively.

All three are pretty much interchangeable and you would want to buy whichever is cheapest and/or easiest for you to get.

From a compressive strength or stiffness perspective. All three foams are the same in the axis that matters, that is to say strength/stiffness through the thickness of the sheet. Spyder has been reported to have a bit better stiffness but the last batch I got was actually less stiff than the last batch of Foamular600 I got. So the differences are small between brands and are less than the differences from batch to batch within the brands.

The stiffness or strength in the other two axis don't matter at all but you can look at the chart that Kevin posted a link to if you like.

The density of the three brands is identical, or at least the batch to batch differences are again greater than any brand difference.

The three foams (Foamular 600, HiLoad60 and Spyder (actually Dow "surfboard foam")) are made by different processes and they do have some subtle (and sometimes more than subtle ) differences in how they handle. Foam always curls to some degree after it is cut and hot wire cutting generally creates foam whiskers (or angle hair). Both of tendencies are a nuisance at best. I find Spyder foam has the least curling and least whiskers when cut, Foamular600 is second best and HiLoad60 is the worst. Spyder foam also is sold by Dow in 5.52" thick blocks that are pretty square and true compared to the other foams. If you need single sheet quantities of foam thickervthan 2" then you will be getting Spyder foam in all likely-hood. The other foams are almost always seen in 2" or 1.5" thicknesses, they can be ordered in thicker sheets but only if you want a LOT of foam.

One caution about the Spyder foam. The batch that I have now does not work well for DLG wings due to poor bonding between the foam and skins. This problem came up the first time I tried to bag a DLG wing with Spyder foam so I'm not sure if it's just this batch or all batches. For now I'm assuming that Spyder foam should not be used when doing really dry layups (very little epoxy) such as is used for DLG wings. I've had no bonding problems with other, more epoxy rich wings.

All the Spyder foam I've bought in this decade has been blue (the Dow trademark color) Aradhana Sing Kalsa reports that he knows how to buy white Spyder foam but I don't know what that's all about or if it is normally available in that color.

You can find lots of foam information by searching the words "spyder" and "foamular600" in this forum. Do an advanced search and specify my user name to find the stuff I've written before.

Phil
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Old Nov 23, 2009, 09:04 PM
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United States, AL, Daphne
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Quote:
Originally Posted by Phil Barnes View Post
One caution about the Spyder foam. The batch that I have now does not work well for DLG wings due to poor bonding between the foam and skins.
Might be too much weight for a DLG but you could use an X-acto knife and score the core in a diamond pattern so the resin would have something to grab onto. Glue a stop on the blade so it only goes 1/16" into the foam. (or less)
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Old Nov 24, 2009, 08:58 AM
Throw a glider!
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Columbus Ohio
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Thanks Phil. I appreciate the response. CST is selling small sheets of Spyder foam (1.75" x 12" x 36") far under $13 for anyone that wants to test some small quantities. It is the blue stuff as Phil mentioned.

The dry layup precaution is what has me concerned. I read about it in the threads I searched. Sounds like a negative trade for little to no gain.

I am working on some high end indoor free flight DLG wings. FYI the world record was just broken by Stan Buddenbohm. 1:43.8 seconds indoors with a 100 square inch glider!
~Jim
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Old Nov 24, 2009, 09:12 AM
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Columbus Ohio
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Thanks for the chart link Kevin, I had not seen it.

I do notice the chart says Foamular 600 has a density of 3 lb/cu' as compared to 2.3 lb/cu' for Hi-load 60. Is that still true with recent batches?

That is a pretty significant difference in density. Interestingly the Hi-load actually reaches the 60-psi rating in thickness but the Foamular falls short.

If those are both true it would be worth seeking out Hi-load 60 if you were working on a very critical project, no?
~Jim
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Old Nov 24, 2009, 10:25 AM
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What I hope you take away from this is the following:

The chart that was posted was last revised in May2003. It reports on just the very few test samples that appear on the chart. I too believed those samples to be typical at one point. I actually spent over $1,000 on a large batch of Spyder foam believing that it would offer the greatest E33 stiffness (stiffness through the thickness of the sheet). When I received the batch, I discovered that it was not as stiff as the HiLoad 60 that I could pick up locally in single sheet quantities.

The bottom line is that foam varies from batch to batch just like balsa wood does. On average, the three foam types; Foamular600, HiLoad60 and Spyder foam are equivalent in density and E33 stiffness. If you have some critical project that is very sensitive to one of those properties, you will need to obtain samples of the foam and test it for density and stiffness to determine which batch best matches your needs, just like shopping for balsa. You don't find contest weight C-grain balsa by shopping for brand name and you don't find the lowest density or stiffest foam (among the three we are talking about) by simply shopping by brand. You must test an actual sample of foam from the batch you will be buying from to know which is best.

To specifically answer your question:

The chart reports the data for a single small batch of Foamular600. That was the first Foamular600 that I ever had and it was obtained by a friend who bought a couple sheets and shipped it to me. Later I bought a full unit of Foamular600 that turned out to be about 2.4 pounds per cubic foot (versus the small batch at about 3.0).
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Old Nov 24, 2009, 01:36 PM
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Columbus Ohio
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Arrgh. One of the big advantages of foam in my mind was the uniformity.

I have my phone number on file with local hobby shops. They call me when a new order of balsa arrives. I show up with my scale and density chart the same day. Many times I buy nothing, but occasionally you get a whole 'log" of 1/4" 4 lb C-grain. Those days are fun.

I am accustomed to this with an organic material, I figured all foam should be the same! At least the density variation in foam is much less than balsa. Besides I am pretty sure the local construction supply is not going to be keen on me weighing and sorting their foam for them.

Thanks again.
~Jim
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