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West Michigan Park Flyers
Brings you How to Build a Foamy
By Ronald Haward
| products for sale this collumn
| My name is Ronald
Hayward, I am 70 years young, I was a designer/draftsman/engineer for all my
‘working days’ and became proficient with AutoCAD and have AutoCAD LT at my
home. I have been involved with model airplanes for as long as I can remember. From
whittling them out of a piece of wood to rubber powered to u-control to R/C to
foamys. I got into R/C in 1989 and into foamys in 2003. I love to build models.
For this article, I have decided to build a and describe the process of a
favorite of mine and several other PCRC club members – a slightly modified
version of a foamy called Chucky – designed by Chuck Auger in 2004. The
original design had a 36” wingspan, my version is 32”. One of the main reasons
I reduced the size is now I can get three airplanes out of two ¼” thick x 24” x
48” sheets of blue “fan fold” foam
insulation. The stuff home builders put under vinyl siding on a house. It comes
in bundles of 25 sheets for around $30.00 at Lowes. I’ve tried the pink, the
green & others and like the blue stuff the best.
Remember, most Foamys are NOT trainers – they are highly maneuverable and very quick –
they have to be to fly indoors.
The first picture is of my current flyable
foamy fleet - from left to right – a
mini Shark Bait, 19 ½” span, made from 3mm (about 1/8”) Depron – below that,
a 15 ½” dia “UFO, a 28” span (my
design), from 3mm Depron – a 28” span (my design) twin from 3mm Depron – a 30”
span (my design) ¼” blue foam and a 30” span Pitts Python bipe using both 3mm
Depron & ¼” blue foam. Details, plans, information, etc. available on
request.
Picture1
| | | Picture #2 shows my work bench with some of
the necessary things needed to build a foamy.
Picture2
In addition to the 1/4"
thick foam, you're going to need some foam-safe CA (medium), some CA kicker, a
hot-melt glue gun and glue sticks, 1/8 or 5/32 dia. carbon fiber rod or tube or
similar to stiffen the wing and elevator, some clear 1 ½” wide packaging tape
(and I found some clear ¾” wide tape at Meijers), some sticky-back velcro, and
colored markers or H2O paint, rulers or yard stick, some weights (hunks of
steel or lead), and a SHARP hobby knife.
A couple of pieces of 4 x 4 wood about 16-24" long are helpful to keep
things square during assembly on the bench.
I use some 3” x 6” balsa blocks I just happen to have. A cutting mat (my
wife has been looking for hers for over a year), is a very handy thing to have
too.
I’m
going to assume you have acquired a plan that you want to build and you have
some basic model airplane building skills. I like to make a template for each
of the major parts so I can replace the plane when I need to. Templates can be
made from card board, old paneling, scrap pieces of ¼” foam taped together,
almost anything you have handy. | |
Picture #3 shows my templates on a 24” x 48”
sheet of foam ready to be traced & cut out
Picture3
(remember, for the second
aileron, flip the aileron template over and trace again). Also is my stainless
steel 24” ruler/straight edge and an extra fine Sharpy marker.
Picture #4 is
the pieces all cut out and cleaned of marker with rubbing alcohol.
Picture4
Be sure to
cut at about a 45 degree angle at each hinge joint to prevent binding.
To
reinforce and strengthen the wing and elevator, you need to add some carbon
fiber rod or tube or something similar. Start by carefully cutting a shallow
"V" groove in the bottom of the wing or elevator with a hobby knife
(I made a ‘tool’ by sticking a #11 blade through a piece of balsa at an angle
so it stuck out about 3/16” – pictures 5 & 6), then "shaping" it
with the rod or tube (see Illustration 1). Cut the C.F. to length(s) required with a
Dremel cut-off disc, and glue in the groove with foam-safe CA and kicker. See pictures # 7 & 8.
 Picture 6
 Picture 7  Picture 8
| | Painting, decorating, trim can be done now
or when finished – I like to do before assembly – Picture # 9 shows the
“canopy” painted with H2O spray paint sprayed into a clean tuna fish can, then
applied with a brush. Colored markers, acrylic paints, etc. can also be used. LOW TEMPERATURE iron-on coverings like
Coverite’s Micro Lite, Black Baron or Tower Hobbies TowerKote can be used also
to dress up your foamy.
 Picture 9
I L L U S T R A T I O N S
I have
planned this plane so I can hinge the ailerons and elevator before assembly –
note in picture #10 how the horizontal and vertical fuse pieces are cut &
notched. One cut going all the way
from the leading edge of the wing opening to the rear of the fuse.
 picture 10 Picture
#11 shows the application of the packaging tape hinge to the top of the stab
& elevator.
 picture 11
 picture 12
Pictures 13 &14 illustrate how to apply the ¾” wide
clear tape to the bottom side – about 2” – 3” apart.
 picture 13  Picture 14 | | I use a pop sicle stick
squared off and sanded smooth to make sure the tape on the backside follows the
taper and contacts the tape on the topside. Again I used low tack green tape
because you can’t see the clear. Use this same method for hinging the ailerons
to the wing and, (AFTER assembling the wing & fuse parts), hinging the
rudder to the fuse. (See Illustration 2).
Make sure all surfaces have plenty of
travel and can move easily.
Ok,
now we can begin to assemble our foamy.
Picture #15 shows the 3 main parts of our foamy put together and held
“plumb, level and square” on the balsa or 4 x 4 wood blocks that you have.
 Picture 15
Once
every thing is about where you want it, we have to square-up the wing to the fuselage.
First, center the wing by measuring from each wing tip to the fuse. Then, to
square the wing to the fuse.
Picture #16 illustrates measuring from the tip of
the stabilizer to the centerline of the carbon fiber tube.
 Picture 16
It really doesn’t
matter what two points you use, just so you use the same points on each
side. Recheck again to make sure all is
square. Hold everything in place with
some weights and begin gluing together with hot melt glue. I like to ‘spot glue’ about two inches apart
as I hold things in place. Then, once I’m happy, I run a small bead the full
length of all joints on the bottom. (see picture #17)
 Picture 17
| | Turn it over and repeat the process on the
top side. Now its time to hinge the rudder in place – the same way you did the
ailerons & elevator.
Reinforce
the front motor mount area with some scrap blocks of white or blue or
pink foam scrap and glue in place with medium foam-safe CA and spray on
some kicker. Hot melt glue can be used if you are quick. Carefully
sand the motor-mount area FLAT with about a 2 degree RIGHT thrust and
use 30 minute epoxy to assemble the 1/16" or 3/32" plywood motor mount
(see illustration 3 and pictures #18 & #19). Use some weight to
hold in place until the epoxy sets.
 Picture 18  Picture 19
Control
horns can be purchased, but I like to make my own from 1/32" thick
plywood or used-up gas cards, gift cards, etc. (see illustration 2). To
install, simply cut a slit on the aileron, elevator or rudder, insert
the horn, align the holes even with the hinge line. Remove the horn,
apply medium CA to the cut and to each side of the lower edge of the
horn, insert the horn back into the slot with the holes lined up with
the hinge line and then spray on some kicker - see pictures # 20 &
#21.
 Picture 20  Picture 21
| | Motors mount in a lot of different ways, but most
out-runners mount to the firewall with or without a separate mounting
flange or bracket. If your motor shaft protrudes beyond the back of
the mounting bracket, you will have to drill a clearance hole for it in
the enter of the firewall. Position the mounting bracket and drill
ONE 3/64” dia. hole in the firewall. (Picture # 22) Install a mounting
screw – do not tighten. Position the mounting bracket and repeat for a
second screw . Tighten the two screws, drill and install the remaining
screws. Place the motor in the bracket and tighten the set screws.
(Picture #23)
 Picture 22  Picture 23
Radio
gear installation is next – I like to put the ESC, Rx and at least one
servo on one side and the battery on the opposite side for balance
reasons. Sticky-backed Velcro works for this about as good as anything,
although some folks use ty-wraps or hot melt. (see illustration #4)
| | Tape the Rx antenna to the underside of the wing, away
from other components. Be sure to use enough Velcro for the battery so
the battery can be moved back & forth to obtain the correct CG.
Some folks solder the motor leads to the ESC leads – some solder
connectors – your choice but if the motor runs backwards, its easier to
change with connectors. Cover joints or connectors with heat shrink
tubing.
Before I install my servos, I prefer to wrap them
with masking tape (the hot melt glue is easier to get off when
switching to a new model). Remove any pre-installed servo arms (don’t
lose those little bitty screws). You can cut holes in the foam or just
stick them in place with hot melt or just secure them in place with
ty-wraps. If you cut holes for them, use hot melt to keep them from
moving. Install the receiver and ESC in place and connect motor leads
to ESC per instructions furnished with ESC. Connect servos and ESC to
receiver per instructions from Rx & ESC.
BE SURE YOUR
TRANSMITTER THROTTLE STICK and THROTTLE TRIM IS ALL THE WAY DOWN, turn
on transmitter FIRST, THEN plug the battery into the ESC battery leads.
If the motor spins, unplug the battery from the ESC, and REVERSE the
‘throttle servo’ on your transmitter. Again, with the throttle stick
all the way down and the transmitter ‘on’, plug in the airplane
battery. With the rudder, elevator and aileron trims set to zero or
centered, move the rudder, elevator & aileron sticks to make sure
the proper servo works (we’ll worry about direction later). With the
three sticks in their neutral or center position, un plug the airplane
battery, then turn off the transmitter.
Here, in picture #24
is the single aileron Servo installed in its location and the servo arm
has had two mini servo connectors installed.
 Picture 24
These
little devices make it easy to make minor adjustments to the control
surfaces. Once all servos have been ‘zeroed’, install the proper servo
control arm - BE SURE TO INSTALL THE LITTLE BITTY SCREW!
Control
rods are made from .039 dia. music wire. File or lightly grind any
burrs off the ends of the wire. Make a ‘Z’ bend in one as follows;
(refer to picture #25) make a 90 deg. bend (A) - then make a second 90
deg. bend about 3/32” from the first bend (B) - now, twist the first
90 deg. bend until it is parallel with the main part of the wire(C).
It may take you a few times to get it just right. Make any additional
bends so the rod lines up properly with the control rod, cut to length
(about ¼” longer than necessary) and install as seen in picture #26.
Repeat this process for all control surfaces.
Picture 25
Picture 26
Ok, almost done. We just need to check a few things, install the prop and we’re ready to make that first flight!
With the transmitter throttle stick all the way down, turn on the
transmitter and then plug in the airplane battery into the ESC leads.
You’ll hear a series of ‘beeps’. Advance the throttle stick about one
fourth up – the motor should spin COUNTER clockwise as you face it from
the front. If not, throttle down and swap two of the three motor/ESC
leads – try again. Face the plane AWAY from you. Move the rudder stick
to the LEFT – the rudder should also move to the left. If not, REVERSE
the ‘rudder servo’ on your transmitter. With the plane still facing
away from you, move the aileron stick to the left – the left aileron
should move UP, the right one DOWN. If not, REVERSE the ‘aileron servo’
on your transmitter. Now move the elevator stick back or towards you –
the elevator should move UP. If not, aww, you know what to do. RECHECK
all control surface movements. If you have a radio that has dual rates
and/or exponential, set the ‘high’ rates at 100% and the ‘low’ rate at
about 65% to start with. For exponential, I’d put in about -35% on low
rate and about -65% on high rate. NOTE all radios do not use the same
+ or – for expo. What you are looking for is LESS control surface
movement when the stick is near the center and MORE movement as the
stick nears the end of its travel. Consult your radio manual!
If you’re gonna use a prop saver, install it on the motor shaft now, and/or, just install the prop and go fly that puppy!
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