epp and epoxy ?

I just bought a flying wing and was wondering if there
was a better way to cover it than the packing tape that
the instructions recommend. I have some left-over
aeronautical fiber-glass, epoxy and microglass. I was
thinking of joing the two halves with a micro slurry,
and covering it with a single layer of UNI glass, except
for the leading edge which might have an extra layer
or two. My questions are:
Will epoxy and slurry bond to epp as well as it does
to hard blue foam ? (Do epoxy and epp have any bad
reaction ?)
Might it be too heavy ? (Or is it overkill ?) It seems
to me that a single layer of FG wouldn't be heavy at all
and might make it border indestructible.
Thanks,
krb
Reply to
Kevin Bailey
Loading thread data ...
In my experience with Zagis, the flexibility of the EPP foam is what makes them so durable. Epoxy will bond to EPP, but the expoxy and glass will likely be heavy and won't be flexible. The fiberglass tape with the packing tape over the top really is the way to go - although one sloper in our club did cover over the fiberglass tape with a low temp R/C film and it came out well. Just use VERY light dustings of the 3M Super 77 to stick the fiberglass tape and spars and you should be fine. Just to be on the safe side, make sure you test the adhesives you plan on using on some scrap EPP (like an outside corner of the wing bed) before putting it on your wing.
Reply to
Tom Simes
I have a Zagi. I think it would bond but I think it's over kill. You might think of doing this in place of ABS, I keep breaking the plastic parts. You may not even need all the tape they call for. mk
Reply to
MK
I think you would find that you will need a LOT of epoxy just to fill the holes in the EPP before you would get good adhesion of the cloth. It would end up making the wing a lot heavier. Also, the glass and epoxy would be a lot less flexibke and would fracture in the minor bumps and bashes that these wings get. EPP is the perfect material to survive this and the tape gives it just the right rigidity.
Reply to
Paul McIntosh
| In my experience with Zagis, the flexibility of the EPP foam is what makes | them so durable. Epoxy will bond to EPP, but the expoxy and glass will | likely be heavy and won't be flexible.
Right -- if you're going to fiberglass it, it'll be strong but fragile. Which is OK as long as you don't crash it, but that sort of defeats the purpose ...
| The fiberglass tape with the packing tape over the top really is the | way to go - although one sloper in our club did cover over the | fiberglass tape with a low temp R/C film and it came out well.
I do all my flying wings in Ultracote now. Looks much better, lasts longer and is a lot smoother. Really, the only downside is that it costs a little more.
There's a lot of web pages out there on modifications to make to your flying wings. Many (like Ultracote, buried control arms and the receiver under the battery rather than in front of it) are very well worth doing.
Reply to
Doug McLaren
That's why I'd use micro slurry under the cloth. Micro slurry is epoxy mixed with several parts microscopic glass bubbles. Very light and strong. It's purpose is to fill the holes and bond to the cloth.
True enough. I measured it would add 100g to a 300g plane.
Here I have to disagree. I have a sample wing which is, although heavier, strong as steel. I can bang the leading edge on the edge of a brick and all it leaves is a smudge of brick. I can also drop a brick on it from eye level, point down, and all that happens is the brick bounces back up to belt level.
In any case, I will take your advice and favor lightness over strength. It does no good to make it strong if it can't fly.
Thanks, krb
Reply to
Kevin Bailey
Interesting. I think we all considered it at one point or another, and just concluded or assumed it would be too rigid to survive crashes. I wonder if it would be possible or worthwhile to carve out most or some of the foam after forming the 'glass. For that matter, maybe form the glass over balsa formers, and ... ;-P Well, that's a whole different realm of construction complexity. The real advantage of carved foam is its simplicity. You could build one entirely with just a hot wire and a kitchen knife.
Reply to
Mike Young
I glassed up most of a picojet. It didn't add a lot of weight and did make it ding proof and snap resistant. And added enough rigidity to make it fly a little better.
The cloth sort of only sticks to the bumps - you don't end up with epoxy fulling the grain...and I used film over the top to make it look good.
If you are worried about that, get some lightweight filler and dilute with water and brush on, and sand first. That fills the hollows.
Finding the right amount of stengthening to still leave it bouncable is a bit of a trick. Use ine layer of thinnets first, and maybe another later in high stress areas..or a layer of thicker glass.
Reply to
The Natural Philosopher

Site Timeline

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.