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Wing Styrofoam for EZ/Cozy


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I've been doing some research on the foam used in the flying surfaces of both the Long-EZ and the Cozy. What I've found is that the original "2 lb/ft^3 Styrofoam FB" called for in the plans doesn't seem to be made any longer. A/C Spruce still sells what they call 2 lb/ft^3 Styrofoam FB so maybe they stocked up on it? Wicks sells "POLYSTYRENE Blue Large Cell expanded 1.6 lb. density". I called both suppliers and the lady I talked to at A/C Spruce had no knowledge beyond what was printed in their catalogue. She gave me a phone number to their distributer which led to a dead end. Wicks sells 1.6 lb/ft^3 pipe insulation. I ordered samples from both suppliers and they are indeed different. The foam from A/C Spruce

is, in fact 2 lb/ft^3 and has a larger cell size than the stuff from Wicks. What concerns me is that the original Styrofoam FB had a compressive strength of 35 psi while 1.6 lb/ft^3 pipe insulation has only 20 psi. That's less then 60% of the strength. Also, there are warnings in the old canard pushers about using only the correct type of wing styrofoam called for in the plans. It specifically says not to use different types with less strength. There is also, by the way, a specific warning against using dock floatation foam which I have heard others say is the same stuff.

 

I would just order the stuff from A/C Spruce and be done with it but A/C Spruce is really expensive. The price difference between suppliers for foam for 1 airplane is $260. Add to that the fact that I would have to pay for shipping from A/C Spruce while I could go pick up the other stuff in my truck and you get probably more like $500 in price difference. Do any of you have any further insight/information on this? Perhaps a Cozy builder could find out since it is still a supported design.

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Good question. I bought a bunch of the 1.6# foam from Wicks this year, and am planning on using it for all flight surfaces.

 

I've heard the blue dock foam CAN be the same foam, but without knowing you could end up with a different density. For me, 1.6 vs. 2.0 is close enough and have heard enough "you can use it" feedback to be comfortable.

 

In fact, I wonder how much weight I'll save with the 1.6# foam vs. the 2.0# foam. 5lbs? :)

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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The replacement for high density Clark Foam is Corecell S-foam or Divinycell H250.

The topic is wing foam, where none of these apply. Also, the Cozy plans refer to Last-a-foam as the Clark replacement, which has always been available. Where does it say (or who is saying) that those types are also replacements?

 

I think I would do some more research on the 1.6 V 2.0 This is not a place to save weight unless the strength is equal to the designed foam.

I'm not actually looking to save weight, just use the foam that I managed to get on sale from Wicks, where it's described as Long-EZ foam. The topic has come up in the mailing lists too, with some consensus being that 1.6lb/ft^3 is okay to use.

 

I appreciate the concern, and welcome any other feedback on the topic.

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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You should save approx 7 lbs for a pair of wings. This doesn't include canard or winglets so they may save you another couple of lbs or so. As you said though, this has nothing to do with weight savings. I'm going to thoroughly run this to ground before going with the 1.6# stuff. I would really like to use it but I'm going to have to be sure it's ok first. If I can't get a definitive answer, I'll suck it up and buy from A/C Spruce.

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I just finished my canard out of foam purchased at Wicks. So, it is the 1.6# foam. Guess I haven't checked the archives well enough, because this is the first I have heard of the issue!

 

On the other hand, there must be a lot of planes out there built from this foam. I think they have been selling it for some time. I am almost positive that Dennis Oelmann buys his foam from Wicks because they seem to know him pretty well. He certainly cranks out a lot of canards and wings.

 

Featherlite on the other hand does not get their foam from either Wicks or Aircraft Spruce. They get their foam from a place local to me in Sacramento. I guess that is probably where I will be buying my foam for the wings.

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I guess I have a short memory.

 

There were at least four posts on the Cozy list on June 2, 2006.

 

Richard Riley dismissed this issue. He stated that the foam density can vary widely and that what Wicks and Aircraft Spruce sells is essentially the same stuff.

 

The density can vary from 1.6 to 2.0, or 1.8 +/- 10%. Maybe I'll go get a large scrap and weigh it and then calculate the density to see what it really is ...

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I will also calculate density on one of the billets I have. I have been told by a reputable source that the QC for foam production is haphazard and that the density might range between 1.5-2.2lbs/ft^3.

 

My only worry was with crushing or impact forces breaking through the skin because of the lighter foam. That also appears to be a non-issue as the skin will absorb the impact/stress in tension and/or compression.

 

Onward and upward for me. :)

Jon Matcho :busy:
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Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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What concerns me is not the density, it's whether or not this is an approved substitute foam. This isn't a matter of density variations between batches of foam, I'm afraid it simply isn't the same foam. According to the canard pushers, foam is never used to transmit primary or secondary loads so the lesser strength may not be a big issue. However, it also specifically says not to substitute materials with less strength. The smaller cell size might affect the peel strength but the only way to find out would be to test it.

 

I emailed Wicks concerning this and received a reply yesterday as follows:

 

"The F200 is the same foam, but it was changed long ago to 1.6 density, in place of 2.0 density. Aircraft Spruce sells the 1.6 also."

 

As I mentioned in my eariler post, I ordered samples from both suppliers. The foam is very similar but does appear to be a bit different. I weighed and measured the stuff from A/C Spruce and it does seem to be 2 lb/ft^3, not 1.6. It also has slightly larger cells and the color is slightly darker than the stuff from Wicks. They didn't tell me anything about compressive strength but Wicks did give me an MSDS number with which I was able to track down exactly what it was on the Dow website. What I'm worried about is the possibility that the type of foam was changed due to the original Styrofoam FB being discontinued and the new stuff was deemed close enough and never tested. I’m afraid Wicks may have assumed it was “the same foam” as it says in the email above and that they may not have sought RAF’s or Nat’s approval for the substitution. It was easy enough to find the strength of the new foam but I had to do some digging to find the original material’s strength. When I did find it I was alarmed to see that the new stuff has less than 60% of the strength of the original. This is what made me start questioning whether or not it is an approved substitute at all. There are other factors such as fatigue strength and no telling what else that may play a part that would have been tested by RAF if they approved it.

 

I’m waiting for replies from emails I sent to Wicks and to RAF concerning this issue. I’ll let you know how it turns out.

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I’m waiting for replies from emails I sent to Wicks and to RAF concerning this issue. I’ll let you know how it turns out.

As the manufacturer of the airplane (at least here in the US) it is up to you to determine the suitability of a given material and your diligence is commendable. I can tell you that I know of at least 6 or 7 sets of EZ wings that were built from the foam at Wicks in the last 10 years or so. All of them are flying fine.

 

You have to remember that the Long-EZ plans were published 25 years ago or so. Manufacturers come and go. Products come and go. A lot of the things that go into our aircraft are not made specifically for aviation. As near as I can tell, the Pipe Insulation foam from Dow is the closest to the original foam that was used back in the 70's. I know of a couple of airplane that used Flotation Billet foam and they seem to be ok.

Rick Pellicciotti

Belle Aire Aviation, Inc.

http://www.belleaireaviation.com

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Amateur surfboard builder here, let me get in on this thread please. Just yesterday stumbled onto this site and thread while trying to figure out exactly which extruded polystyrene foam, XPS, the plane builders are using. The surfboard builders, us included, are having delam issues with all the XPS offerings and thru much homework have not found the plane builders to be having any delam probs, true?? We've been following Rutan methods since the 70's, only recently we kicked off the effort to use the plane builder materials and methods for the boards, we're using Dow bouyancy billets. All board builders are having delams and have mostly given up the effort on XPS in favor of expanded polystyrene, EPS, densities from 1 to 3 pcf, reference www.swaylocks.com. The notation on this thread about a past Canard Pusher note not to use bouyancy billets is very interesting and any feedback, references on if the plane builders are having blue wing foam delam issues please. I've got some pretty good notes on Dow XPS densities from talking with the reps at Dow but need to get that data better organised before posting. Thanks

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Wicks may have assumed it was “the same foam” as it says in the email above and that they may not have sought RAF’s or Nat’s approval for the substitution.

That may very well have been the case, but I'm not concerned with the end result. I know of other builders using the 1.6, and Rick knows of flying wings. That, with the other information and feedback, is good enough for me.

 

The surfboard builders, us included, are having delam issues with all the XPS offerings and thru much homework have not found the plane builders to be having any delam probs, true??

If there were any delam issues, even a small amount, it would be a major topic on all places where these planes are discussed.

 

I wonder if you're truly using the Rutan techniques:

  • Polyester/vinylester resins? Don't they eat polystyrene? I'm sure we use different epoxy. Maybe you need to make 200mph surfboards?
  • Preparation? Paint and squeegee foam w/"micro slurry" (glass balloons mixed w/epoxy) to fill voids and establish glass-to-glass surface. Layup glass when wet.
  • Dark colors keep heat in the sun, melting the epoxy underneath.
Hope that helps.

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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Thanks Jon Matcho, I knew that if the plane builders were having delam it would be a huge topic and can't figure why the board builders have it as such a big problem when the plane builders don't. The board laminaters are real pros, do fantastic, thoughtful work, commercial and amateur. Epoxies are being used, many of the same ones lised in A/C Spruce catalog, eg. West, Jeffco. Boards need to be works of art so water clear resin is important, Resin Research Epoxy is commonly used. Rutan method surface preps, micro slurry, are being used with equal delam failures to, no pore filler, or alternative "sealing" methods such as lightweight wall Spackle smear. A tip from this site, I'll be vacuuming the foam pores before micro slurry next time. Temperature, Yes, a big factor, but this has been addressed big time and is probably only part of the issue. A white or clear board sits on beach, or roof of car, or in hot car but that can't match the temp of a white wing sitting on the asphault tarmac at Phoenix or any 100F inland location. I can't figure it, the board glassers are real experts, laminate all day long every day, the product needs to be perfect or its trash and those guys can't avoid the delams. I'm a once in while builder still intent on using the Rutan methods, we've got the video Building Rutan Composites, we still own 2 bouyancy billets and starting the next build, thats why the current push to get feedback. Past Dow XPS notes are in front of me now for the product data I've got, more later, Thanks. John C.

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Thanks Jon Matcho, I knew that if the plane builders were having delam it would be a huge topic and can't figure why the board builders have it as such a big problem when the plane builders don't. The board laminaters are real pros, do fantastic, thoughtful work, commercial and amateur.

I wonder if you are getting point loads on your boards that we don't get on airplane wings? The delaminations could travel or spread from there. In other words if something pointy like an elbow or knee impacts the board, that force can cause a delamination. Then, as the board flexes, the delamination would spread. This is just theory, I have never been on a board.

 

I do know that surfing and flying run in the same families though. My friend, Dave Hirschman, worked his way through college as a professional surfer and he is a pilot. Dave's mom was one of the first women to build a Vari-eze.:)

Rick Pellicciotti

Belle Aire Aviation, Inc.

http://www.belleaireaviation.com

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Here's some data on Dow blue foam. This data is from Fall '04 when I talked to a rep in the architectural foam department at Dow Styrofoam. See www.styrofoam.com > products, architech, the toll free numbers are the same as '04. I was asking about the Hi Load product line and Buoyancy billets. Hi Load 40 psi compressive strength 1.8 pcf. Hi Load 60 psi 2.2 pcf. Hi Load 100 psi 3.0 pcf. Buoyncy billet sheets 25 psi 1.6 pcf. Buoyancy billets blocks untrimmed about 1.8 pcf. End of that data. The 2 billets we own right now are coming in at about 2.0 pcf with an iffy kitchen scale and getting the volume dimenions 24"x10"x96" is tough because of the billet's wavy, round cornered, outer shape. I didn't weigh them when we first got them and they've been soaking up ambient humidity for 2 years. A/C Spruce lists 2 large cell blue foams, and one small celled blue foam, and now I'm getting confused.

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Thanks RPelliccioitti for commenting on the surfboard delam issue. Yes, the point loads from hands knees and feet cause compressed foam and associated delam, its one of the worst board durability problems, we and many folks are working on the prob, but that's a durability prob. The laminating delam prob is occuring right in the shop for some people, soon therafter for others, it doesn't seem to be a use, durability thing. Our specific problem on 2 boards could be chaulked up to some other variables, first time using the blue foam, carbon fabric hard to wet out and see thru to see whats going on with the wet laminate...and other rank amateur variables, but the pro and pro/am industry is stymied by the Extruded Polystyrene. One commercial manufacturer in Oceanside Ca. near San Diego, talks about his particular problem, assessment and solution on his web site www.xtrsurfboards.com >FAQ. XTR and other smart enouph folks are always talking about the blowing agents coming out of the foam. Wouldn't the airplane wing just be blowing apart at altitude if that was the issue?? I'm going to persevere to duplicate the Rutan exact methods on next build using glass to see thru the laminate, we've also got the Rutan build booklet, Moldless Composite Homebuilt Sandwich Aircraft Construction, that book combined with the Video ought to do the education job?? Thru this thread I've confirmed that the plane builders are not gettng delam issues, that in itself is a big help toward figuring out what is going on with the surfboard laminations, thank you.

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Here's some data on Dow blue foam. This data is from Fall '04 when I talked to a rep in the architectural foam department at Dow Styrofoam. See www.styrofoam.com > products, architech, the toll free numbers are the same as '04. I was asking about the Hi Load product line and Buoyancy billets. Hi Load 40 psi compressive strength 1.8 pcf. Hi Load 60 psi 2.2 pcf. Hi Load 100 psi 3.0 pcf. Buoyncy billet sheets 25 psi 1.6 pcf. Buoyancy billets blocks untrimmed about 1.8 pcf. End of that data. The 2 billets we own right now are coming in at about 2.0 pcf with an iffy kitchen scale and getting the volume dimenions 24"x10"x96" is tough because of the billet's wavy, round cornered, outer shape. I didn't weigh them when we first got them and they've been soaking up ambient humidity for 2 years. A/C Spruce lists 2 large cell blue foams, and one small celled blue foam, and now I'm getting confused. ADDitional note, this week I spoke with the Dow rep at the Composite Panel dept to confirm that the Bouncy Billets are the same chemical material as the other Dow blue foams and that the billets are produced with same attention to chemical, build consistency as the other foams, yes on all questions of quality control.
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The laminating delam prob is occuring right in the shop for some people, soon therafter for others, it doesn't seem to be a use, durability thing. Our specific problem on 2 boards could be chaulked up to some other variables, first time using the blue foam, carbon fabric hard to wet out and see thru to see whats going on with the wet laminate...and other rank amateur variables, but the pro and pro/am industry is stymied by the Extruded Polystyrene.

You are right, if gas venting out of the core was a problem, we would be blowing wings off left and right. This is not an issue in my opinion but at the same time, I would not use a billet that was blown yesterday. It makes sense to use a stable billet that has had some time to settle down. How long? I don't know. Perhaps some of the others can shed some light on it.

 

I went and read a lot on the site that you mentioned. I can think of a couple of other possibilities since you mentioned that this is happening just out of the shop:

  • Improper handling of the materials and core. Grease on hands, oily working surfaces, etc are a NO-NO.
  • Insufficient wetting out of the fabric leaving dry spots or dry areas.
  • Too dense of a core material which leads to the inability of the epoxy to bind with the core.
  • Inadequate surface prep. Cores have to be clean and vacuumed, removing all sanding dust and other contaminants before glassing.
One might think that the more dense the core material is the better it would be. The problem is that the only bond between the epoxy and the core comes from the ability of the epoxy to get down in between the beads in the foam and "set its teeth in the material". If the core is too dense, the epoxy cannot get a grip.

 

One of the things I do with my cores is that I roll a Top Flight Woodpecker over the core. I do this after vacuuming the core and before applying the micro.

 

I didn't read it anywhere on that site. Are they vacuum bagging these layups?

Rick Pellicciotti

Belle Aire Aviation, Inc.

http://www.belleaireaviation.com

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Other possible issues for a good foam-epoxy bond:

  • cannot have any oil/silocone spray in the air or shop (air tools spitting oil?)
  • 24-hour warm cure (@70degs minimum?) If it were my wings, I'd leave them alone for a couple days.
  • I can't see how you'd do both sides at once; you're not, right? Using peel ply and/or sanding after first side cure is necessary.
This is an interesting issue, with something that might be found to benefit us airplane guys.

 

One of the things I do with my cores is that I roll a Top Flight Woodpecker over the core.

You MUST be an RC modeler...

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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Thanks J. Matcho, Rick P, We are gettng out beyond my own limited experience so I went back to the Swaylocks board building forum to review and relearn what the real guys have experienced. I'll put you onto some interesting threads, but first. Should me move this conversation to a new thread here to allow the original EZ Ahab questions to come thru?? I'll leave that to you. The interesting threads: www.swaylocks.com>discussion>general discussion>general discussion search,type in XPS delamination. 22 results should show. Look at the thread titled, XPS foam gassing problem or XPS roll call. The players Bert Burger and Greg Loerh are real commercial builders/innovaters. Loerh puts out the Resin Research Epoxy, its good, Burger is very knowlegable, commercial and development as you'll see. A look at this thread and you'll know as much as I do except for our own particular delam problems under opaque carbon already mentioned. I've got 4 new test laminated coupons waiting for peel, bash and overheat tests starting today. John C.

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There's seems to be as much hot air over there as anywhere else I've seen. :) I've never heard about "foam gassing" in the same sentence/topic as our blue foam until now. It may be the case that the epoxy doesn't stick to polystyrene, so Rick's woodpecker technique may be worthwhile.

 

Loerh puts out the Resin Research Epoxy, its good...

I wouldn't use it on my airplane. :)

 

I've got 4 new test laminated coupons waiting for peel, bash and overheat tests starting today.

Nothing beats actual testing.

 

The other thought that comes to mind is type of glass you're using. If you want to make a surfboard like a wing, glass the bottom w/2 plies of UNI alternating at 30 degree angles from the longitudinal axis (longways; like a shallow 'X', one +30degs and the other -30degs). Glass the top of the board the same way, but add a 3rd ply so the strands run longways down the board. Use our type of fiberglass weaves AND an epoxy system approved by Rutan for building wings and you might be able to say you "did it".

 

This was an interesting diversion, and it does relate to wing making in aircraft. I'm actually curious enough to want to test glassing an unprepared foam surface. Still, I'm not sure how much more interested everyone will be in the topic of "delamination of surfboards caused by blue foam gassing", but feel free to have at it. Hijaak the thread all you want.

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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Thank you aviation Folks , for the tips. A woodpecker device is being made up right now, test panel with fine nail holes being done today. Surface prep attention double checked for everything. Replicate Rutan methods more exactly, eg, correct micro slurry is really quite thin at 50/50 resin micro. The plane builders have this composite thing down. Moving on to the next steps now, gotta shape up a new full size panel and get it into the surf for durability testing :-) and if it survives, the panel really should get off to Mexico for some real life thermal tolerance tests :-) I'll let you know how things go. thanks again. John C

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...eg, correct micro slurry is really quite thin at 50/50 resin micro.

Sounds like that's not enough micro. I don't measure -- not sure that many do -- but instead just add the micro until I get the desired consistency. Still, the only problem w/having it too wet is that the part will be heavier than otherwise. Actually, the mechanical bond should be stronger, IMO.

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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