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Sep 20, 2020, 08:51 PM
IT'S NOSE HEAVY!!!!
cityevader's Avatar
Thread OP
Discussion

Noob to EPP; questions. .. jw60 build


I've only built one foamie, a Slope Monkey, and butchered it.
10 years later, I'm now starting a JW60...

Is there a concise THREAD, comparing/contrasting the different methods (or specific links to each topic) to finishing an EPP plane? Something like:

3m77/bi-directional tape.
Thinned Goop.
Spackle/sand/CA-ing the sanding dust.
PU/sand/PU.
etc...?
..... PLUS all of the benefits/drawbacks of each method, ALL in one thread?

Google searching RCG gets lots of "white noise" that I'm not after.

I've got Lam Film/ "monokote"/Solartex, but am ACTUALLY looking for threads of the differences between different"substrate" treatment.
My build intent is a semi-disposable DS trainer.
..... But... I flew a M.O.M. race at the Slot and a JW60 took the win... So, it might get some frontside use if it survives the backside.
Last edited by cityevader; Sep 22, 2020 at 10:33 PM. Reason: Title change
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Sep 20, 2020, 09:26 PM
Just Toss It !!!
MATIN's Avatar
Wait......Let me get my baseball bat.....
Sep 20, 2020, 09:49 PM
F3Foamie Pilot
Slopemaster's Avatar
If I were in your shoes I'd identify and review some EPP build threads that you feel makes sense and you like.

There are many differing opinions on the best way to approach an EPP build.

IMO, two important considerations would be structural strength and a finish that meets your expectations. These two things will vary from builder to builder.

BTW, that warmed my heart hearing that a JW60 won a slope race. I would love to race my Bluto against a glass slipper someday.
Sep 20, 2020, 10:41 PM
Registered User
chip.greely's Avatar
Chad

1. Build it straight
2. 10mil NS On the Wing (Stiff as sh t)
3. Thinned GOOP on 5mil NS on well rounded fuselage
4. Servo linkage per NCFM (thru wing)

Easy peasy
Sep 20, 2020, 10:59 PM
Registered User
And oddly almost nobody builds the plane according to the printed directions that come with it which recommends covering with 3M spray glue then the ultra thin colored packing tape. So many threads....so many different ways to build it from Uber light to a 3 pounder.
Sep 20, 2020, 11:43 PM
Just Toss It !!!
MATIN's Avatar
Quote:
Originally Posted by Slowper
And oddly almost nobody builds the plane according to the printed directions that come with it which recommends covering with 3M spray glue then the ultra thin colored packing tape. So many threads....so many different ways to build it from Uber light to a 3 pounder.
What a hobby! ....Eh??!!!!

It 's pretty much the same for those whose hobby is skinning cats.
Sep 21, 2020, 12:01 AM
Registered User
Daemon's Avatar
3m Super77 + strapping tape + colored tape (aka.. Zagi tape) was pioneered with the original Zagi wing in mid/late 90's.
It makes it light, but entirely too destructible and the tape is very hard to iron (it expands first
with heat then shrinks so it's easy to add wrinkles or make it peel up at the edges).
Eventually the tape just starts to get torn up and it needs to re-covered.

I love thinned Goop on molded EPP as it makes for a permanent bond to any covering,
and it also pretty good on wire cut/sanded EPP fuselages as it really adds a lot of strength
to the foam.
Thinned Goop on wire cut EPP wings does some odd things though. Because it cures by evaporation
it will form a skin on the outside and then make the foam first swell up as the gas
is forced inside the wing, then slowly shrink back to original size as the gas escapes. This
can cause wings to bend or twist. The trick to avoid this is to let it cure mostly through
to add strength to the foam (but will make all the cell walls pretty prickly) then
come back and hit it with a little toluene or Xylene (or PERC) to soften it up and apply the tape and iron-on
covering on top of that. Generally too much of a hassle on wings so I generally avoid it
there and use it only on fuselages.

I've never cared for spackle because it tends to be the weakest link between
the wire cut foam, tape and covering and will disintegrate on inpact *but*, I have seen it used
in a very creative way. I've got a couple EPP aircraft that were designed and built for
FPV use (one of them is the giant Graugans plank, which some have seen me fly at Weldon).
The designer/builder uses spackle + thinned Goop, and works it into the foam
let's dry, sands, adds another layer, repeat until smooth, and then lays Kevlar cloth
over it (could use Super77 just to tack it down), and works thinned Goop through it
(as you would thin epoxy) to bond it. Paint over the top.
These planes are simply indestructible, and I've never had any de-lamination
of the skin from the foam even in some pretty serious crashes.

All that said, if I were trying to build a JW60 today, I'd probably just
do stock taping scheme on the wings, adhered any way you like, and then
10 mil CP laminate for a somewhat bouncy build, or 10 mil DL laminate if I want
it to be able to cut other planes in half.
Sep 21, 2020, 09:24 AM
Registered User
gp49's Avatar
Hi Chad,

Here are a couple links for builds:

https://www.jwglider.com/build-logs
Sep 21, 2020, 05:21 PM
IT'S NOSE HEAVY!!!!
cityevader's Avatar
Thread OP
I've searched for some build logs here, and the ones I want to see have pictures no longer viewable, and links that no longer work.

Ima gonna New Stuff the wings, and may just experiment with the thinned-Goop fuse....it's really applied AFTER taping it, right?
Sep 21, 2020, 05:37 PM
the occasional flyer
rothlisburger's Avatar
Yes
Sep 21, 2020, 06:18 PM
DS Junkie
Screamin' Eagle's Avatar
Stu has a slew of build logs on his blog. (See what I did there?)

1000MPH

https://www.rcgroups.com/forums/member.php?u=17060
Sep 21, 2020, 07:37 PM
Registered User
^+1
Sep 21, 2020, 08:48 PM
Registered User
Daemon's Avatar
Quote:
Originally Posted by cityevader
it's really applied AFTER taping it, right?
I actually do it before as well, with the caveats I mentioned above. The real power of
thinned goop is only realized if it can bond the foam cells as well.
Sep 21, 2020, 10:03 PM
Expert Rekitter
Quote:
Originally Posted by chip.greely
Chad

1. Build it straight
2. 10mil NS On the Wing (Stiff as sh t)
3. Thinned GOOP on 5mil NS on well rounded fuselage
4. Servo linkage per NCFM (thru wing)

Easy peasy
Thats how I built mine that won the Mom heat, can't go wrong. Rips on backside. Build a balsa fin if your gonna break the sound barrier!
Sep 21, 2020, 10:27 PM
DS Junkie
Screamin' Eagle's Avatar
Balsa fin is mandatory. Covered in film it weighs the same as the coro. Don't skimp on glue when attaching it to the fuse. There shouldn't be any play there side to side or tracking will suffer.


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