Shrinking Dacron over foam

[IASCOTT]

I been toying around with the idea of building a bread loaf foamie teardrop. I recently cover a Piper Cub with a water based covering system and I really like this system. What I was wondering was will the foam handle having a iron run over it at 350 degrees Fahrenheit with out any melting problems. Or will I have to run stringers to keep the fabric off the foam. Dacron is a great fabric to work with it shrinks easy with an iron and it's as strong or stronger than canvas with a thinner material. Seams are easier to hide and it come in 72 inch width.

QGM

[KCStudly]

The pink Foamular 150 has a max service rating of 165 deg F (Foamular 150 Specs)

There is another booklet that cautions against exposing it to sunlight with the printed black labels facing the sun, or when covered in black plasitic, such as that used as moisture barrier in ground applications (Foamular & Solar Heat Precautions).

GPW (Glen) has indicated that it can take boiling water (to soften it for bending and/or to thermally expand dents back out), so we know that it can take some incidental temperature excursions, but 350 deg F sounds like it would be pushing it to me. Easy enough to try a little experimentation with some scraps.

Also, unless you are just going for the insulation value, I would think twice about spacing the skin out from the foam. The strength of the panel is due in large part to the high percentage of contact/adhesion between the stabilizing foam and the tension member/skin. I suppose if you laid a grid of splines, stretched the Dacron around and attached it to the underside of the floor really well...better yet, wrap it all the way around encapsulating the floor, then the shrinking action of the Dacron could pull enough tension into it to create more of a truss like arrangment, rather than a stressed panel. Does the Dacron adhere when it is ironed, or will it slip over the splines as it shrinks?

I guess you would also have to worry about the foam bowing in, to some degree, unless you skinned the inside with thin ply.

Interesting concept. Not sure how that would work compared to a true stressed panel or "torsion box", but there sure are plenty of "canvas" covered tubular framed airplanes running around out there.

I have an image of a skewed diamond pattern grid with a little twist or gentle arc shape to the splines telegraphing through the skin. Now that would be a cool visual effect!

[Treeview]

Skin car...

http://www.gizmag.com/bmws-gina-concept ... dy-p/9483/

[Wobbly Wheels]

The only use I know of for Dacron is for sails, so excuse what might be a dumb question....

If the Dacron simply shrinks over the substrate without adhering to it, you cut put something like craft paper on the outside of the foam as an insulator (like ironing some clothes).
Another thought might be to use a heat gun with a spreader nozzle so you can see exactly how much heat you are applying.
Or mount a bunch of lamp sockets to a board and use heat lamps to slowly bring it up to temp ?

[IASCOTT]

I plan on doing a semi sip panels the interior will be a birch or maple plywood bonded to the foam. The outside will be the dacron fabric stretched tight with the iron. If that's not possible then I will route some grooves in the foam and glue in some stringers to keep the fabric above the foam. I think I'll do a test panel as suggested and see what happens. On the leading edges of the wings I glue some felt to help soften the bumps of the screw heads used to attach the leading edge skin to the ribs. Now that could be a possibility but I really wouldn't want to have to cover it all in felt then fabric. A test piece is in order inquiring mind need to know. Plus I just love shrinking fabric it's one of the cool part of being a airplane mechanic.

Scott

[atahoekid]

Sounds cool, Scott. Seems like we may have found another way to skin a Foamie. Can't wait to see the test sample

[Martinup]

Hi all:

Found this really good and informative batch of You tube Videos showing the use of Dacron Fabric , Echo filler , (several coat proccess); folowed by a Three part Water Based Polyurathane painting proccess for those of you looking for a beautiful Auto body finish.

I really like the way this stuff shrinks up and with no wrinkles around tight radiuses, . . . good for Covering Wood, Metal, and Polystyrene.

You will find many many informative videos by this nice Guy , "Dan " who shows you how to use all of the above products to cladd Air Planes. The way I figure it if it is strong enough to hold up on an air frame, wings and all, Just think what neat things we can do with it on Tear Drops.

I spoke to Dan on the phone today and ordered a starter kit to play arround with. I hope to use it on my build and I will share the results on my build page.


I also invited Dan to join in on our forum to answer any question others might have. I think this stuff is really neat and seems easy to work with and apply. It may be a bit pricey for some but for this caliber of finish I think it is well worth it and compared to aluminum or Stainless steel finishes it is vary comprable and I think much lighter.

Dan can even make you a professional sprayer of autobody finishes.

So check out the gret Youtube videos:
[youtube] http://www.youtube.com/watch?v=rl9I3FOA ... E46A3F6FC2 [/youtube]

The contact information is as follows:
Stewart Systems
Ph: 1 . 888 . 356 . 7659
http://www.stewartsystems.aero
Email: info@stewartsystemaero

For our build I have to come up with something a little different to clad my roof. But I thought it may be especially useful for you foamlings out there.

So check it out and post your thoughts and I will convince Dan to Join in the discussions to provide answers.



Enjoy,

Martin

[IASCOTT]

I just got done covering a Piper Cub with the Stewart System. I really like this system and I have done just about every system out there for covering an airplane. The glue for gluing the fabric on is mile ahead of the other systems. There is virtually no smell associated with this glue no fire hazards and no mask needed up until you go to spraying. I will say there is a learning curve when it comes to this water base paint. It needs to be applied the way they say other wise a person will have troubles. I'm use to solvent based paint and I would revert to my old ways while spraying and it always got me into trouble. With a little practice a person can get a great finish with this system. The real nice part is the paint that is used on the fabric can also be used on the metal parts. But like everything else in aviation it is kind of expensive.

Scott

[Martinup]

Hi all:

Man I didn't see the heading on this topic otherwise I would have posted onto this one . . . Anyway check out the topic above this one. There are some good info links and supplier contact input coming up soon I hope.

Can the administrator or moderator combine these two topic titles into one.

Thanks,

I'll try and Martinup next time,

Martin

[Martinup]

Hi KC;

I was on the Owens Corning site researching this and for roof application they recomended using the therma pink product line. I read through the spces really quickly and menteioned that it can take temps up to 250 degress.

Anyway the videos I saw on Dacron suggest to get shrinking the temps are around 250 degress. To get adhesion to a metal frame they recommend I beleive 275 degrees to 350 degress.

The temperatures may have to be played with but the glue applied to metal is one application and the same glue put on polystyrene may not require such a high temp to get good adhesion.

From what Dan from, "Stewart Systems" mentioned to me that he thought this might be possible to do.

I've invited him to join us here and share his knowledge and skill with this product. Might save us all some trial and error.

Also search it on You tube to see a whole bunch of videos on Airplane Applications.



Martin

[eaglesdare]

i don't know how i missed this thread. i will check out the above link as mentioned and see about combining. but i will read it first. i just didn't want anyone to think i was ignoring.

but i think this is a really cool idea. please report back after testing this.

[GPW]

Having covered many SMALLER aircraft (flying models ) some 100” WS or more .... with a variety of heat shrink or “paint shrink” fabrics, fibers, mylar films , and combinations thereof , over open frame structures (stringer and formers ) and over Foam , especially beaded foam , both cut and moulded.... I think it would be totally unnecessary in the real world dynamics of a functioning TD trailer ....
Just more Overkill , overbuilding , over considering .... and expense... JMHO

Good covering technique with common heavier canvas produces a simple and durable structure (sandwich) with no need to squeeze the structure together further, for a somewhat mystical added strength (?)... and then , there’s always “too much of a Good thing “ , and a shrinking skin can WARP a surface dramatically ... I can’t tell you how many good wings I turned into Bananas by “over shrinking”


And I suspect there is some natural shrinkage going on anyway , even with the canvas and T2 alone .... everything did seem to dry quite Taught when It was all over ... a few weeks later it seemed even tighter ... and has stayed that way for some time now ...

[Martinup]

Hi GPW:

You mentioned beading . . . what did you mean exactly? I can understand the warping. With my build the roof is kind of the crown. The connections are not the same as with a flat roofed trailer whre you have many more and different contact points.

I want to get this as nice as possible inside and out. By the way did you preshink your canvas? There is quite a nice expansive feeling inside this shape.



Martin

[IASCOTT]

Here is a method for finishing the dracon once it applied and from the pictures he got a nice finish. Plus you got to love a Pietenpol Aircamper. With dacron you can get a much smoother finish with less work. I don't know as I go as far as this person did but it is an option. Plus the cost is back down there where it a wash.

http://home.comcast.net/~mmorrison123/piet.html

For covering of complex cures you can't beat dacron fabric. And if shrunk in stages starting at 250 degrees then 300 degrees then a final shrink at 350 degrees you won't warp you teardrop out of shape.

Scott

[GPW]

Bead board foam ... the kind made up of all the little balls (beads) of foam ... Used that long before we ever got to the Blu' stuff ...
Na, I didn’t pre shrink my canvas ... maybe that helped ... ?

Scott , I mentioned aircraft style framed TDs with fabric covering in the past ... Not much response , But I sure do like the idea personally ... Pretty Piet‘ huh !!!