Hand-crafted Giant Scale R/C
warbirds & Golden Age Racer kits! Racers : Gee Bee Z, sport scale model, GeeBee, R-2, Super
Sportster, GeeBee Y, R2, R1, Z, Y, Foam building techniques & technology,
F-4U Corsair, F4-U,
P-51, Mustang, P51, P-47, RC, Thunderbolt, P47, F8F Bearcat, PT-19, Fairchild,
Focke-Wulf, FW-190A, Sea Fury,
A6M3, Zero, P-40 Warhawk, P40, B-25 Mitchell, radio control .
Foam Building Technology
Using Jack Devine's Foam Bond Cement
An easy way to keep this building page
is to print it out! Just set your printer properties to 'Landscape', and
then print a set of full-width color instructions to use at your building table!
Building Technology has come a long way. Here
we will show some building techniques used in applying sheeting and capping to
the foam cores, which are the heart of each lightweight, super-strong Jack
Devine model. One of their building secrets is their Foam-Bond contact
cement, which is the perfect glue for a flawless sheeting job!
All of NW HobbyTech's kits include foam core fuselage structure and flight
surface components. The edges of the
wings and control surfaces are capped using laminated strips of balsa and
aliphatic resin. We used Sig-Bond aliphatic resin here for that
purpose. First, lightly sand the foam to open the pores. On straight
parts, standard balsa stock will be used. On bands and curves, three thin strips are laid together with the glue, and once wetted
with the glue, they
are taped securely to the edges using Lacquer Masking Tape. After the laminated
strips dry, the Lacquer Masking Tape doesn't stick and peels right off!
edges are then sanded flat as an extension of the surface they are glued
to. The strips will become the outermost part that the sheeting is glued
to. A square edge is essential for good glue contact where the sheets meet
the edges. Remember to lightly sand all foam
surfaces to open up the pores before applying any adhesives! These glues
are designed to grip the foam, but they must be able to penetrate the foam to do the job
the way they are supposed to.
During the cutting process, the cutting wire leaves
a hard, thin crust on every surface of the foam. Whenever wood, foam or
anything is to be glued to foam, the foam must be sanded lightly to break that
point, it's usually good to have an FAA inspector check your project to see how
it's going. As you can see from the photo, we called inspector REN.
One reason we have included this photo is to show the fuselage
construction. The fuse comes from the factory just as you see it here with
Ren. The edges of the ring sections (where you see adhesive lines) are
made a little higher than the centers of the ring sections. They are built
this way on purpose. Before sheeting, you will want to take a long, flat
sanding block, and sand across those adhesive joining-lines, and meld the lines
of the fuselage into one long, gradual line up to the bevel in front. The bevel you
see in the nose should be left as it is, so you can easily sheet that with a
flat piece of balsa and simply trim off the edges afterward.
Inspector REN was tough
but fair. We were a few dog biscuits short after he left, but everybody
was happy, and the inspector was well-satisfied that the job was progressing
We're putting together surfaces for a (racing) Gee Bee Z here, and you'll notice that the
wing shown here has an optional spar slot. (Optional
= not stock / but at no extra charge) We've installed a hardwood spar using
the Sig-Bond, making sure it does not extend out past the foam surface
level. As it began to dry, we simply wiped away the excess glue with a
damp cloth, leaving a smooth surface. While the capped edges and the
spar dried, we joined sheets of high-grade balsa provided in the kit using the Sig-bond and
the Lacquer Tape, leaving us with large sheets of balsa that are somewhat larger
than the surfaces we were to be covering. The construction video does a
really good job of showing how these sheets are joined. NW HobbyTech also
has a dedicated page here for Joining Balsa
Sheets , which has a lot of information to help you with your sheeting
job as well. Once the large sheets have dried and the tape has been removed, then
we lay the surfaces on the sheets, and cut around them with some room to spare, as
Applying Foam bond cement. Foam Bond is THE secret weapon for easily sheeting foam with balsa.
Lightly sand foam surfaces first!
an ordinary 3" knapped paint roller (NOT a foam type
roller!), apply Foam
Bond in one generous, even coat over the entire surface that you will be
sheeting. NOTE: Before you start to apply
Foam Bond, make sure that whatever you have to do to the foam core underneath is
the coat as you would a fairly heavy coat of paint, but only apply one
coat. Apply a similar even coat to the entire inside of the sheeting where
the surfaces will meet. Wipe off any excess foam bond from any surfaces
you are not attaching sheeting to, using a wet cloth. Do this NOW, and do
not allow excess Foam Bond to dry on any surface. You'll see why soon!
Now, allow both surfaces to dry COMPLETELY until all
of the Foam bond has gone clear and is no longer tacky to the touch. Once
dry, it will seem like nothing would stick to it now, but this is when you must
be the most careful! This is THE perfect time to sheet up. Don't
let the treated pieces sit a long time, like overnight. That's a bad
thing. The foam bond will lose an excessive amount of its contact-cement
properties if it dries too long. Roll on the Foam Bond only when you are
completely ready to sheet up, when the only thing you'll have to wait for is the
glue to dry enough to go from white to clear, then you're ready.
DO NOT allow any two
surfaces with dried Foam Bond on them to touch each other unless you are doing
it purposely. You will not
get a second chance!!
Wetting down the wood.
This is another one of those big secrets that makes or breaks a sheeting
job. We used a 50/50 mixture of ordinary ammonia & water in a spray
bottle with good spraying capacity. MAKE SURE you open windows and doors
for ventilation. Ammonia smells BAD!
Wet the wood thoroughly on the OUTSIDE, which means the side WITHOUT the glue on
it! We wet it until it fairly drips off the balsa. Don't allow any
of the wetting mixture to get on the side with the dried glue on it!
Sheeting! Okay, this is
the really fun and interesting part, but you have to be careful! Lay the wetted side DOWN on
a flat, smooth table top, glue side UP. We're sheeting a wing here.
Take the leading edge of the wing (glue side DOWN), touch down the very inside
tip of it to the very inside corner of the balsa, then carefully follow with the
rest of the leading edge until the entire leading edge is laying squarely down
across the farthest side of the sheet. You are now committed.
leading edge is now securely fastened to the sheeting, and you could not make it
let go if you wanted to, so follow along CAREFULLY here!
on the front leading edge and downward as well, begin a slow, careful rolling of
the wing backwards toward you. Maintain the pressure as you go, and do not
stop the rolling or the pressure until you have rolled the entire chord of the
wing from front to back. Even if your core has a warp to it for some
reason, the flat tabletop will make it come out perfectly flat and
Follow this up by rolling the balsa firmly with a laminate
roller to make sure the glue adhered firmly and evenly, as shown here. We
got our roller (and Lacquer Tape) at Home Depot. It's a roller for applying formica to countertop
There! You've just sheeted a whole wing panel on one
side! Trim the edges to the point where you will be able to sand them square with the caps.
Now, on the flip side of the wing, roll on Foam Bond immediately to sheet
that other side in exactly the same
fashion. It's important that both sides are
done as closely together on the same day as possible! The drying of the
balsa on both sides of the wing must occur simultaneously or nearly so to
guarantee a straight
washout basin at the tip!
The first thing we did (before we applied Foam Bond) was to lightly sand the
wing so that the rounded-out symmetric surface rounded nicely into the line of the washout
basin. The one thing that will probably look impossible to you will be
trying to figure out how to sheet the washout section of the wing, which
basically goes IN, while your sheet of balsa basically rounds OUT with the wing,
as you can see in the photo. But it's simple! Make sure you use the 50/50
mixture to wet the sheeting down thoroughly.
Now, after a minute or two to
allow the mixture to work itself into the grain, we ran the roller straight down
the middle with a LOT of pressure! That attached the middle, but left big
rolls to the left and right. We then rolled off to the left and right,
taking in parts of the rolls each time, and used the roller to compress the
balsa! The Ammonia and water mixture allowed the balsa to compress, and
the Foam Bond held the compressed balsa securely, and we didn't get ONE
wrinkle! Foam Bond, 50/50 spray mixture, and a good roller.
That's what it takes! After drying, the completed wing was so strong and light we almost
couldn't believe it!
Important Note: The balsa sheeting is
critical to the structural integrity of the built-up surface or fuselage. Once it is dry,
sand it heavily. If you desire smoothness, use some brush-on superlight sandable
filling sealer (Sig
Mfg. sells a VERY nice product for this) to fill the grain, and lightly sand it, you'll
love the baby-smooth results, and you won't remove substantial amounts of material. By doing this you will still have the full thickness of
balsa, and your plane will be incredibly strong, as advertised.
At Jack Devine Models we want to stress the importance of following
instructions! Not following them can cost you a plane...or worse!
These planes are essentially exoskeletal, like a big
beetle. The skin is the strongest part, but MAN, is it EVER
strong......so take anymeasures you can to retain its full thickness!
Sheeting the fuselage inside.
took the sheets of balsa and cut pieces that were close to the sizes of the
sides inside the fuse, and trimmed them in until they fit fairly close to the
edges, but not too closely. We found that after the Foam Bond dried that
if we reached in with the piece of sheeting and lifted it UP into place that we
were able to avoid making accidental contact with the inside before we were
ready to press them together! This "Box" you see here that is created through this sheeting is ultimately reinforced with tri-stock,
and the resultant strength is incredible.
The fuselage will not
be bent. And there is still the outside which will be covered with
sheeting and / or runners. This massive GeeBee 'Z' fuselage when completely
sheeted, with stringers, weighed under 3 pounds. It is without a doubt the
TOUGHEST fuselage I have ever built in my life. Every other
This building page
here to help you gain an understanding of how advanced foam-core models really
are. Jack Devine is a wealth of information on this subject, and he's
always more than happy to talk about it. The instructional videos that
come with every kit have a lot more information on this, we've only scratched
the surface here! Jack Devine
Kits are a lot of fun to
build, and they don't use toxic or irritating glues or compounds to build
Check out these Jack
Just Pick, Click, and FLY to their page!
Each and every
model is built using the advanced foam-core technology shown above.
Jack Devine Models
14906 114th Ave. N.E.
Kirkland, WA 98034 - 1031
Business and Information line: 1- 425 -
822 - 8130
Toll-Free Order Line (Not for information): 1- 800- 897- 0717