KIT NO. FK-OOl
SIG 46" FLOATS - GENERAL DESCRIPTION
These floats are designed to work on any large radio-controlled model
airplane weighing from 12 to 25 pounds. They could be used on models
heavier than 25 pounds if the model isn't physically too large in size. The
floats will support the heavier weight on the water quite easily.
However, models over 25 pounds will usually be physically too large to
handle well on this size of floats. As a general rule, the length of the
floats should be about 2/3 to 3/4 length of the model's fuselage, give or
take a few inches. These floats will work best on a model with a 62 to 70
inch long fuselage, having a 6 to 9 foot wingspan, weighing 12 to 25
pounds.
The finished floats, including all the brace wires, mounting hardware,
and water rudder, normally weigh about 3-1/2 pounds when all done. If
your model's regular wheel landing gear weighs 1-1/2 pounds (as the Sig
1/4-scale Cub does) then the actual weight difference between the water
and land configurations of your plane will be about 2 pounds. Models to
be flown on floats must be amply powered to handle the extra weight
and also extra drag. As a general rule, if your airplane can presently be
safely flown in land configuration at 3/4 throttle or less, it will have
enough power to fly with floats.
The addition of these floats on a model should not change its balance
point very much. The floats by themselves balance near their "step" (at
former F5) when finished. If they are properly mounted on the model
with the step located at the model's balance point, then the model
shouldn't become either nose heavy or tail heavy because of the addition of the floats.
PERFECT FIT ON A SIG CUB
The pre-formed brace·wires and all of the mounting hardware in this kit
are designed for mounting the floats on a Sig 1/4-scale Piper J-3 Cub or
Sig Clipped Wing Cub. Those are the airplanes that the floats were
originally designed for and tested on at our factory. Note that the fullsize plan shows the floats mounted on a Sig 1/4-scale Cub. Also, this instruction book describes every step involved in making the Sig Cub/float
installation. If you intend to mount your floats on a Sig 1/4-scale Cub,
everything you'll need is included in this kit. The only modification required to the model is the installation of another grooved I.g. block farther back in the fuselage to mount the rear brace wire in. It's a simple
process to install the block even if your Cub is already covered and
finished (see page 9).
MOUNTING
ON OTHER MODELS
If you intend to mount your floats on other than a Sig Cub you'll probably
have to modify, or possibly make all new brace wires to fit your particular
airplane. Every airplane will be a little different, depending on the exact
configuration of the bottom of the fuselage. Some models may need a
taller front brace wire. Some models may need a taller rear brace wire.
Some may need the spacing between the tops of the brace wires changed. Although the actual mounting won't come until after the floats are
built and finished, it's a good idea to start planning for the installation
now. Unfortunately, we cannot provide instructions or complete parts to
cover every possible installation. You'll have to use your own ideas and
ingenuity when mounting these floats on models other than a Sig Cub.
See page 12 for more information.
2
GLUES
We recommend that the floats be assembled with either epoxy glue
(such as Sig Kwik-Set or regular Epoxy), or with cyanoacrylate "super"
glue (such as Zap, Jet, or Hot Stuff). Do not use other glues unless you
are sure that they will be waterproof when dry.
CAUTION: Some people have experienced allergic reactions when
exposed to epoxy or cyanoacrylate glues. This is very rare. However,
it is always important that such glues, and also paints, thinners, and
solvents, be used with adequate ventilation to carry fumes away.
NOTES BEFORE BEGINNING
CONSTRUCTION
Any references to right or left refers to your right or left as if you were
seated in the cockpit of the airplane.
To build these floats you will need a good straight building board at least
45 inches long. The building board can be a table, a workbench, a reject
"door core" from the lumber yard, or whatever - as long as it is perfectly
flat and untwisted. Cover the top surface of the building board with a
piece of celotex-type wall board or foam board, into which pins can be
easily pushed. Don't hesitate to use plenty of pins during assembly to
hold drying parts in correct position.
When pinning and gluing parts directly over the full-size plans, cover the
plan with wax paper or plastic kitchen wrap to prevent gluing the parts
to the plans.
Don't use a ball point pen for making marks on the model during construction. If not sanded off, these ink marks will show through the
model's final finish. Use a pencil instead of a pen.
Leave all the die-cut parts in the sheets until needed in construction.
Remove pieces from the sheets carefully. If difficulty is encountered, do
not force the part from the sheet. Use a modeling knife to cut it free.
All of the other kit parts can be identified by the "COMPLETE KIT PARTS
LIST" on page 14. Sort the different sizes of sticks and sheets into in-
dividual piles to avoid confusion during building. Cut all long pieces of
balsa first, followed by medium lengths, before cutting up any full length
strips into short pieces.
Any model parts mentioned in this book, but not furnished in the kit, are
marked by an asterisk (*).
SANDING BLOCKS
An assortment of different size sanding blocks are indispensable tools
for model construction. A good general purpose block can be made by
wrapping a full 9" x 11" sheet of sandpaper around a piece of hardwood
or plywood. Use three screws along one edge to hold the overlapped
ends of the sandpaper. Put 80 grit paper on the block during general
construction. Switch to 220 grit paper for final finish sanding just before
covering.
SANDING
BLOCK
3/4" x 3" x 11"
HARDWOOD BLOCK
Another handy block can be made by gluing sandpaper onto a 24" or
36" long piece of aluminum channel stock. Most hardware stores carry a
rack of aluminum in various sizes and shapes. This long block is very
useful for sanding leading and trailing edges accurately.
Finally, glue sandpaper onto different sizes of scrap plywood sticks and
round hardwood dowels. These are handy for working in tight places and
for careful shaping where a big block is too hard to control.
3
...................
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.......................................
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FRONT PLYWOOD DOUBLER
"KEY TO DIE-CUT PLYWOOD PARTS"
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l:illi:li:1
REAR PLYWOOD DOUBLER
111':'11::1
MARK PARTS IN KIT
ACCORDING TO THESE DIAGRAMS
FRONT PLYWOOD DOUBLER
iYl~
3/32" PLYWOOD
118" LITE-PLY
1 REQUIRED
2 REQUIRED
118" LITE-PLY
2 REQUIRED
118" LITE-PLY
118" LITE-PLY
1 REQUIRED
2 REQUIRED
118" LITE-PLY
2 REQUIRED
(e.) Glue all the formers Fl through F9 onto the Lite-Ply Top Sheet.
Use the alignment marks provided along the edges of the Top Sheet Pattern to aid in getting the formers properly located. Also, use a small
triangle or other 90° object to make sure the formers are perpendicular.
Let dry.
(1.) BASIC FLOAT ASSEMBLY
The following instruction sequence describes building one float at a
time. When finished through step (lp.) on page 7, repeat the sequence
to build a second float.
(a.) Since the float has a perfectly flat top, the best way to assemble it
is upside down on the building board. Cut the "LITE-PLY TOP SHEET
PATTERN SHOWING FORMER LOCATIONS" loose from the full-size
plan and pin it down flat on the building board. Cover it with wax paper
or plastic wrap for protection.
(b.) Pin the 1/8" x 3" x 44-112" Lite-Ply Top Sheet in place on the pattern. NOTICE: Look at both sides of your Lite-Ply Top Sheet before pinning it down. One side will be perfectly good while the other side may
have a few small knots or other imperfections. The knots are harmless
strengthwise, but for appearance sake make sure the best side of the
Top Sheet will be on the outside of the finished float.
HELPFUL HINT: You will find that it's a lot easier to push pins
through the plywood parts with a pliers than with your fingers!
(f.) Refer to the "Key To Plywood Parts" on page 3 and find the diecut plywood sheet containing the Front and Rear Plywood Doublers.
Mark each doubler according to the diagram. Be sure to notice in the
diagram the proper locations of the four little holes that are already prepunched into each doubler. These holes mark the locations for the Nylon
Mounting Brackets that will be added later. Identify the holes now to insure that you know which way the doublers should be put in the floats.
When you are positive of their correct location, glue the doublers in
place.
(c.) Glue and pin the Special Shaped Balsa Top Corner Stringers in
place along both edges of the Lite-Ply Top Sheet. Align each stringer
very carefully so that it is right on the edge of the plywood.
rn~
SPECIAL SHAPED
BALSA STBINCEBS
FRONT VIEW
\..'---
LITE-PLY TOP SHEET
~:,:,."
ALIGN
EDGES
(d.) Refer to the "Key To Plywood Parts" on page 3 and identify all of
the die-cut lite-ply formers F1 through F9. Mark each former with the
correct number and then remove them all from the sheets. Glue formers
F5A and F5B together, aligning the edges carefully.
LlTE-'
f5B
TOPS'""
-.\
\
F7 -'"
5
(g.) Drill through all the pre-punched holes in the Front and Rear
Plywood Doublers with a 9/64" or No. 28 drill bit. Drill completely
through the doubler and the lite-ply top sheet.
(i.) Cut to length the 1/4" sq. Balsa Center Keeland the 1/4" sq. Balsa
Front Corner Stringers that go in the notches of formers F1 through
F5A. Glue and pin these pieces securely into the notches. It works best
to start at former F5A and work forward one former at-a time, bending
the sticks down to fit in the notches. Use plenty of pins to hold the sticks
tightly in place until dry.
Install 4-40 blind nuts in the holes. Tap the blind nuts in with a hammer
until the prongs are completely imbedded into the wood. Spread epoxy
glue over the blind nuts to keep them firmly in place. Be careful not to
get any glue in the threads of the blind nuts.
(j.) When completely dry, unpin the float from the building board.
Carefully block sand both sides of the framework until the lite-ply top
sheet and the balsa corner stringers are flush with the formers. For best
results, use a fresh sheet of 80 grit garnet sandpaper on a sanding
block. Don't press too hard against the balsa stringers while sanding or
they may give. Use long, light strokes along the length of the float.
(h.) Cut the 1/4" sq. Balsa Center Keel and the Special Shaped Balsa
Rear Corner Stringers to fit in the notches of formers F5B through F9.
Glue and pin in place. Note: Both of the Rear Corner Stringers can be
cut from one piece of 48" long special shaped balsa stock.
(k.) Glue one sheet of 3/32" x 5" x 48" Balsa Side Sheeting on each
side of the framework. When dry, trim the edges of the balsa sheets
flush with the framework.
6
(I.) Carefully block sand the bottom of the framework to get the center
keel, corner stringers, and side sheeting all flush with the bottoms of the
formers. Be careful at the front of the float to bevel the 1/4" sq. balsa
center keel equally on both its right and left sides. There should be a
slight peak down the center of the keel when done.
(n.) The Lite-Ply Bottom Front Sheeting is provided die-cut. Refer to
the "Key To Plywood Parts" on page 3 and mark the pieces in the diecut sheets according to the diagrams on that page. Be sure to write on
each piece which edge is the center seam. Then remove the pieces from
the die-cut sheet and trial fit them on the float without glue. You may
have to touch up the center seam edge of each piece slightly with a sanding block to get a good tight fitting joint. When satisfied with the fit, glue
the Bottom Front Sheeting pieces in place. Use plenty of pins to hold the
pieces securely in place until dry.
(m.) A piece of 1/8" x 6" x 24" Lite-Ply is furnished for the Bottom
Rear Sheeting that goes from former F5B to former F9. It's best to trim
the lite-ply to a fairly close fit before gluing it on the float. First trace the
outline of the float on the lite-ply, cut it out about 1/16" or so oversize,
and then glue it in place. When dry, trim and sand the excess off flush
with the balsa side sheeting. Avoid cutting or sanding into the balsa
sides.
When dry, trim and sand the excess lite-ply off flush with the sides of the
floats. Avoid cutting or sanding into the balsa sides.
(0.) Glue the 1-112" x 2" x 4-112" Balsa Nose Block onto the front of
the float. When dry, carve and sand to a pleasing shape thatflows into
the basic contours of the rest of the float.
7
Sand the side-view of the Nose Block to the shape shown on the sideview of the full-size plan.
Sand the top-view of the Nose Block to a semicircular shape as shown
here.
If carving isn't one of your strong suits, try this simple procedure. First
use a razor saw to lopp off the biggest unwanted corners of the Nose
Block.
The Nose Block is now basically done. Finish it up with a little fine sandpaper to smooth out any rough spots and round the corners slightly.
Sand the Nose Block even with the float sides, top, and bottom. Make
the Nose Block a continuation of the float shape.
(p.) Finish sanding the entire float smooth with 220 grit sandpaper to
prepare it for finishing. Round the corners as shown in the cross-section
drawings.
NOW GO BACK TO STEP (la.) ON PAGE 4, AND REPEAT THE PROCESS UP TO THIS POINT TO BUILD ANOTHER IDENTICAL FLOAT.
8
(2.) MAKING THE SPREADER BARS
(a.) Two pieces of 1/4" x 1-1/8" x 19" plywood are provided for making the Spreader Bars which link the floats together. Draw the lines
shown in the photo below on each end of both Spreader Bars. Measure
carefully and draw the lines with a sharp pencil.
(e.) Bolt the Spreader Bars, along with the Nylon Mounting Brackets,
in place on one of the floats. Use the 4-40 x 3/4" Mounting Bolts provided. As you're tightening down the bolts, use a 90· triangle as shown
below to insure that each Spreader Bar is square to the float when viewed from above. Line one side of the triangle up with the edge of the
float's lite-ply top sheet and the other side to the spreader bar.
(b.) Hold (or tack glue with "super glue") one of the Nylon Mounting
Brackets in position between the drawn lines and carefully mark the four
mounting hole locations.
(f.) Now bolt the other float to the other ends of the Spreader Bars.
Use the 90· triangle again to insure that the float is bolted on square.
(c.) Drill the mounting holes through the Spreader Bars with a 1/8" or
No. 31 drill bit.
(3.) WATER RUDDER CONSTRUCTION
(a.) A 1-1/2" long piece of triangular shaped basswood is provided for
making the Rudder Mount. Use a sanding block to round off the 90· corner of the mount as shown here.
BASSWOOD RUDDER MOUNT
/
A "'"~ROUND
CORNER
FULL-SIZE PATTERN ~
(b.) Use the 1/8" o.d. x 1-1/2" long brass tube supplied as a bearing
for the hole in the rudder mount. Push the brass tube carefully into the
hole until it is flush with the wood on both sides.
(d.) Sand the Spreader Bars to final shape. Simply round the edges
and smooth out any rough spots.
SAND
TYPICAL CROSS-SECTION
OF SPREADER BARS
"
R
BASSWOOD
RUDDER
MOUNT
~
CORNERS
~-~-~~-j/~-j0--ROUND
BBASS TUBE BEABINC~
9
(c.) Glue the basswood rudder mount onto the rear end of the LEFT
float. Make sure it is centered and straight. Let dry.
(g.) Assemble all the water rudder parts as shown and check to see
that it turns freely.
(d.) Sand the basswood rudder mount, with brass tube installed, flush
with the top and bottom surfaces of the float.
(4.) MOUNTING THE FLOATS TO A SIG 1I4-SCALE
PIPER J-3 CUB OR CLIPPED WING CUB
The finished floats can be mounted on a Sig 1/4-scale Cub using the
brace wires and mounting hardware supplied in this kit. Nothing additional should be needed. The float's front brace wire mounts in the same
L.G. Block that normally holds the front wire of the Cub's standard
wheel landing gear. The L.G. Block in the Cub that normally holds the
rear wire of the wheel landing gear will not be used for the float installation. Instead, a new Rear L.G. Block must be installed further back in the
fuselage to accomodate the float's rear brace wire. The exact location for
this new Rear L.G. Block is shown on the float plan. Getting the location
correct in the model is very important! If you install the block too far off,
the brace wires furnished may not fit properly. Measure carefully in
these next steps!
(e.) Remove the lite-ply water rudder from its die-cut sheet and sand
the outer edges round.
(f.) Trial fit the 3/32" diameter wire horn into the slot in the lite-ply
water rudder. Alter the slot a little if necessary for a good fit. Then lay
the water rudder down on a piece of wax paper or plastic wrap and glue
the horn into the slot permanently. Reinforce the horn installation byapplying a small patch of lightweight fiberglass cloth(*) and epoxy glue
over it, on both sides of the rudder.
(a.) Measure from the CENTER OF THE GROOVE in the Front L.G.
Block back exactly 6-3/8" along the bottom of the fuselage near one
edge. Make a mark there with a sharp pencil or fineline felt tip pen.
Repeat the measurement and make a similar mark along the opposite
edge of the fuse bottom.
63/8"
NOTE: These instructions assume that you are retrofitting these floats
to a finished Sig Cub. If your Cub is uncovered, you can skip step (4a.)
and simply make the 5-9/16" measurement called for in step (4b.) from
the back corner of the Cub's standard rear I.g. block (see side-view float
plan).
10
(b.) Now measure back from the two 6-3/8" marks an additional
5-9/16" along each edge. Draw a line between the two 5-9/16" marks,
completely across the bottom of the fuselage. Extend the line a little
ways around the corner onto the fuse side. This line is where the
CENTER OF THE GROOVE in the new Rear L.G. Block will go.
(c.) Using a sharp new razor blade or modeling knife, cut through the
model covering on the 5-9/16" line. Also, cut through the covering for a
little ways along the edge of each fuselage side so that the covering can
be pulled back, exposing the model framework. Use some masking tape
to hold the loose covering back out of the way for the next step.
(d.) Notch the inside, balsa portion of the Cub fuselage side to receive
the new Rear L.G. Block. Do not notch into the outer lite-ply portion of
the fuse side. The notches should be 1" wide and 1/2" deep, same as the
block. Make sure that the CENTER OF THE GROOVE in the L.G. Block
will be located exactly at the 5-9/16" line. Epoxy the L.G. Block securely
into the notches, flush with the bottom of the fuselage. Let dry.
cyanoacrylate "super" glue. Double glue the seams to make sure they
are down securely. After the glue is dry, reshrink the Koverall with a hot
air gun. Lightly sand the seams with fine sandpaper and then repaint
the patched area. When dry it should look as good as new!
(f.) Solder 5/32" 1.0. Flat Metal Washers onto the axles of both the
Front and Rear Brace Wires. Note that the washers should end up being
15-7/8" apart, as shown in the front-view on the plan. That's the same as
the distance between the Nylon Mounting Brackets on the floats.
SOLDERING HINT: Slip a short piece of Sig Heat-Proof Silicone Fuel
Tubing(*) onto the axle of the brace wire, and push the tubing right up
against the washer to hold it in correct location for soldering. The tubing
will also keep excess solder from getting on the wrong side of the
washer. After the solder cools, cut the fuel tubing off of the wire.
(g.) Insert the Front and Rear Brace Wires into their
Mounting Brackets. You'll have to take the Mounting
side loose from the float long enough to slip the wires
5/32" 1.0. Wheel Collars supplied to lock the wires in
(e.) Glue the loose covering material back down to the model
framework and to the new L.G. Block. Pull the covering as tightly as
possible back into its original position. Choice of glue for this will depend
upon what type of covering material is on your model. Our Cub in the
photos is covered with heat-shrinkable Sig Koverall fabric, painted with
dope. The Koverall can be glued back down with either Sig-Ment glue or
respective Nylon
Brackets on one
in place. Use the
the brackets.
(h.) Next install the Diagonal Brace Wires. This assembly is critical
because the Diagonal Brace Wires link the Front and Rear Brace Wires
rigidly together and establish the final geometry of the floats in relation
to the model. Ideally, we want the flat tops of the floats to end up parallel
to the 0° datum line of the Cub's fuselage. This is the procedure for in-
Ii ystalling
the Diagonal Brace Wires that we have used with good results:
First you need to secure the Rear Brace Wire perpendicular to the top of
the floats. Use a 90° triangle and a piece of 1/4" thick scrap plywood to
align the wire. Draw two lines, 5/32" apart, exactly in the middle of the
Spreader Bar to locate the 90° corner of the triangle. Tack glue the
triangle and plywood in place to hold the wire solid.
Next link the Front Brace Wire to the stationary Rear Brace Wire by tack
gluing a couple scrap balsa sticks between them. The tops of the Brace)
Wires should be exactly 11-7/8" apart. Measure from the center of one
wire to the center of the other.
11
Solder the bindings with a heavy-duty soldering iron, rosin core solder,
and plenty of soldering paste. The secret of soldering a good strong joint
is to get the wires and binding hot enough to melt the solder by
themselves. Don't melt the solder with the iron and then try to get it to
stick to the cool binding. Solder won't flow into the binding and stick to
the wires if they aren't hot enough. First hold the soldering iron on the
binding and let the heat build up in the wires. Touch the solder to the
binding occasionally'until it starts to melt. Add soldering paste and keep
melting solder into the joint until the binding is completely full. Reheat
the joint as needed to keep it up to temperature while soldering. Be
careful when soldering the lower bindings not to melt the Nylon Mounting Bracket (you can take the bracket off while soldering if you make
sure the wires don't shift). Cover the floats during soldering with a cloth
so that dripping solder and paste will not fall on the bare wood.
After all the joints are cool, clean them with a little dope thinner or other
solvent on a rag. Break away the tack glued 90° triangle and the balsa
and plywood jig supports.
(L) Set the completed floats in place on the fuselage. The Brace Wires
are to be held in the grooved blocks in the fuselage with four Molded
Nylon Landing Gear Straps. Notice in the photo below that the Landing
Gear Straps should be installed as near to the edge of the fuselage as
possible, right up against the Brace Wire where it starts to come out of
the groove. This is done to insure that the floats cannot shift sideways in
the groove once all four straps are screwed in place.
The Front and Rear Brace Wires are now rigidly linked together in correct alignment. Bind the Diagonal Brace Wires in place using the soft
copper wire provided. Use approximately 2 ft. of wire for each binding.
(j.) To install the Nylon Landing Gear Straps, first make sure that the
floats are properly centered in the grooves. Hold the Straps in place and
mark the hole locations on the grooved blocks. Then use a 1/16" drill bit
to drill pilot holes in the blocks for the screws. Next screw the Straps in
place using the #4 x 1/2" Sheet Metal Screws provided.
12
SIDE- VIEW ALIGNMENT
SIG 1/4-SCALE CUB
0°
0°
When top of floats are level, model
should also be level or slightly nose up.
0°
0°
•••
BALANCE POINT
(k.) Double check the final alignment of the floats to the Cub fuselage.
Set the Cub, with floats mounted, on a smooth flat surface and slide
scrap wood blocks or books underneath the front and rear ends of the
floats to keep the model from tipping fore or aft. Now set a small
carpenter's bubble level on top of one float and shift the blocks in or out
until the level indicates that the float top is perfectly level. Now step
back 10 to 20 feet and eyeball the alignment of the Cub fuselage. Does it
appear to be level with the floats, slightly nose up, or nose down? If
you've assembled the pre-formed brace wires accurately, it should sit
very close to level. If you can't tell for sure by eyeball, move the bubble
level to the bottom edge of the Cub's side windows and/or on top of the
stabilizer. Both of these places are 00_00with the Sig Cub's fuselage 00
line.
Slight adjustments to the final alignment can be made by cutting small
shims from 1/64", 1/32", 1/16", or even 1/8" thick scrap plywood(*) to
fit between the Nylon Mounting Brackets and the Spreader Bars. If you
want to raise the nose slightly, put shims under the front mounting
brackets of both floats. To lower the nose, put the shims under the rear
mounting brackets. Use the shims as necessary to get the Cub fuselage
level with the top of the floats.
being off a 1/4" or so won't make any difference at all in performance.
Notice on the float plan that the Cub ended up with the step slightly
behind the model's normal balance point, and this location has performed very well. In fact, we've shifted the Cub's balance point around a little
with the installation of different engines, hot plug battery, etc., and none
of the changes altered the model's float performance to any degree. Aim
for getting the step as close as possible to your model's projected
balance point.
Secondly, the floats must be accurately aligned with the model in the
top, front, and side-views. From the top and front views, they should be
perfectly straight and square in relation to the airplane. Looking from
the side-view, when the tops of the floats are level, the airplane should
also sit level or with its nose slightly up. In the Cub installation, the floats
and fuselage datum line are exactly parallel (00_00) to each other. With
the Cub's large flat-bottomed wing and positive wing incidence relative
to the fuse, this alignment performs well, lifting off the water effortlessly
once flying speed is reached. If you're planning to put the floats on a
model having a fully symmetrical wing and 00-00 wing alignment, you may
want to have the entire airplane sit slightly nose up on the floats. If
necessary small changes can be made to the final alignment after test
flying by using thin plywood shims under the nylon mounting brackets,
as described for the Cub installation.
Plan out your installation by first drawing or taping a side-view of your
model's fuselage on the float plan. Don't forget to consider both the step
location and the incidence angle of the floats in relation to the fuse, as
just discussed. Next decide where you want to locate the grooved L.G.
Blocks in relation to the model's structure. You may be able to locate the
blocks so that the pre-formed Front and Rear Brace Wire supplied for
the Sig Cub can be used in your installation. If that doesn't prove possible and new brace wires will have to be bent, locate the grooved blocks
wherever it is most practical. Keep in mind that the location of the
spreader bars and nylon mounting brackets on top of the floats should
be left unchanged. Also try to keep the front and rear grooved blocks
about 12 to 15 inches apart in the model, to achieve best geometric
strength in the layout of the brace wires. Once you've decided on the
best locations for the grooved I.g. blocks, install them permanently in
the model.
(5.) MOUNTING THE FLOATS ON OTHER MODELS
The Cub/float installation just shown can provide useful guidance for
mounting these floats on other models. The Cub mounting hardware
should also be useable in most cases. When planning your installation,
just remember two important points concerning the final alignment of
the floats to the model;
First, the "step" of the floats should be located right under, or just
slightly behind the model's balance point. The exact step location is not
super critical, just as long as you're fairly close. On models of this size,
Bending a set of new brace wires to fit your particular model is basically
a matter of trial and error. Set the assembled floats on a large flat surface and use scrap wood blocks or books underneath the front and rear
ends to hold the floats in perfectly level position. Put a small carpenter's
bubble level on top of one float, and then shift the blocks in or out until
the bubble level indicates that the floats are perfectly level. Next use
more wood blocks, books, paint cans, or whatever to jig up your airplane
in proper position over the floats. It may take a little time to get the
model securely blocked up in correct alignment, but make sure you get it
right. Then take a wire coat hangar, or other soft bendable wire, and
trial bend it to fit as one of the brace wires. Unbend and rebend the coat
13
hangar until you get the shape just right to fit in the grooved I.g. block
and the nylon mounting brackets. Once you're satisfied with the fit, draw
the shape of the coat hangar on paper and bend your actual new brace
wire out of 5/32" music wire to match the drawing. Repeat the process
to develop patterns for the other brace wires. When they are all done,
bind and solder the new wires in permanent position. Be sure to read
the instructions in this book about mounting the floats on a Sig Cub. You
may find them helpful in making your installation.
(d.) One 4 inch length of nylon tubing is provided for making the cable
guides that go on the rear brace wire (see plan). Cut the 4" piece into
two 2" long pieces using a razor blade or sharp modeling knife. Heat the
middle of one of the pieces with a hot air gun or hair dryer until it softens
enough to be bent 90° without buckling. Hold in shape until it cools. Do
the same for the other piece of tubing. Trim the excess length off both
ends of the guides so they match the ones on the plan.
(6.) COVERING AND PAINTING THE WOOD PARTS
The two floats, the two spreader bars, and the water rudder must be
covered and painted to make them waterproof. Completely disassemble
these parts from the brace wires and from each other so they can be
finished separately.
We have tried two different finishing methods on our prototype floats.
Both provide a durable, flexible, long-lasting, waterproof finish.
METHOD I: Cover your floats with light-weight fiberglass cloth (3/4 oz.
per sq. ft.), adhered with either slow drying epoxy glue or thin
cyanoacrylate adhesive. Then paint the covered floats with epoxy primer
and epoxy color paint (like K&B or Hobbypoxy). If you use slow drying
epoxy glue to adhere the glass cloth, apply it sparingly to avoid adding
too much weight. Use a plastic epoxy spreader (Sig SH-678) or an ordinary playing card to scrape off all the excess epoxy once the cloth is
saturated. Remember, the strength will come from the fiberglass cloth,
not from the glue. Extra glue adds weight, not strength.
METHOD II: Cover your floats with Sig Koverall polyester fabric
adhered with Sig Nitrate Dope or Sig Stix-It adhesive. Then paint the
covered floats with Sig Supercoat clear and color dope.
Both of these methods are commonly used by many modelers for covering and painting their entire airplanes. We assume since this float kit is
an accessory for a completed model, that you may already be familiar
with one or both of these finishing methods. Which finishing method to
, use is really a matter of personal preference. The finished weight of the
floats comes out about the same either way. If you haven't ever painted
a model before, we suggest that you consult your local hObby dealer or
local model fliers for their recommendations.
The brace wires and nylon mounting brackets can also be painted with
epoxy paint if desired for appearance sake. They don't need it for waterproofing.
Enamel paint of any kind is not recommended for the floats. Most all
enamels get brittle with age and could develop hairline cracks that
would let water seep in.
Iron-on plastic or cloth coverings are not recommended. No matter how
well they are put on, inevitably a seam in the covering will loosen enough
to let water seep in.
(7.) FINAL ASSEMBLY AND WATER RUDDER HOOKUP
(a.) Once the wooden parts are completely covered and painted,
reassemble the floats for the final time. Squirt a little silicone rubber
sealer(*) in the bolt holes when screwing down the nylon mounting
brackets for waterproofing.
(b.) Mount the floats back on the model. If the Front and Rear Brace
Wires fit a little loose in the grooves on the landing gear blocks, squirt a
bead of silicone seal(*) in the grooves just before putting the wires in.
Wipe off any excess silicone, and then let dry before flying. Also, on a Sig
1/4-scale Cub, it's a good idea to cover the open bolt holes left in the bottom of the fuselage from the wheel landing gear installation with small
pieces of plastic tape so water can't get inside.
(c.) To hookup the water rudder steering cables, your model must
have a control horn on each side of its rudder. The Sig 1/4-scale Cubs
already have this. If your model doesn't have dual rudder horns, you'll
have to install them or come up with an alternate method of actuating
the water rudder. The horns should be as low as possible on the rudder
for easiest cable hookup.
(e.) Bind the nylon tubing cable guides onto the
left leg of the rear brace
wire with regular household sewing thread(*).
Locate the bottom guide as
low as possible on the leg.
Locate the top guide about
4 inches up the leg above
the bottom guide. You
can't put the top guide all
the way to the top for most
airplanes
because the
steering cables must be
able to exit the guide and
connect to the rudder
horns without rubbing on
the fuselage. Coat the
thread bindings with epoxy
glue to make them waterproof. Let dry.
(f.) A 1/16" o.d. x 1-1/2" aluminum tube is provided for making
crimpers to secure the ends of the steering cables. Cut the aluminum
tube into 4 pieces 3/8" long each. A single-edge razor blade works real
well for this. Just hold the blade against the tube with medium pressure.
Roll the blade and tube forward and backward a few times while pushing
down. If the blade is sharp it should cut through the soft aluminum tube
clean and easy without collapsing it.
14
(g.) A 12 foot length of braided steel wire is provided for making the
steering cables. Cut it into two 6 foot long pieces. Slide one of the
aluminum tube cable crimpers over the end of one of the cables. Next
loop the same cable end through the water rudder steering arm and
then back through the cable crimper. Cinch up the loop in the cable to
make it smaller, but not so tight that it binds on the arm. Smash the
cable crimper flat with a pliers. Repeat the process to fasten the other
steering cable to the other side of the steering arm.
(h.) Pass the loose ends of both steering cables together through the
cable guides on the rear brace wire and then back towards the dual rudder horns. Determine which cable goes on the right side of the rudder
and which goes on the left for proper steering direction. Lock the
model's air rudder and the float's water rudder in neutral position. Then
crimp the ends of the steering cables to the rudder horns in the same
manner you did the water rudder ends. Be sure to pull the cables tight,
taking out all the slack, before smashing the aluminum cable crimpers.
NOTE: If you want the steering cables to be removable, we suggest that
you incorporate #7 size fishing swivels(*) into the ends of the cables
where they hook to the air rudder ..
COMPLETE KIT PARTS LIST
BALSA
4 - 3/32" x 5" x 48" Side Sheeting
2 - 1-112" x 2" x 4-114" Nose Blocks
4 - 114" x 114" x 48" Sticks for Center Keel and Front Corner
Stringers
6 - Special Shaped x 48" Sticks for Top Stringers and Rear
Corner Stringers
DIE-CUT
PLYWOOD
- See "Key to Die-Cut Plywood
Parts" on Page 3
SAWN PLYWOOD
2 - 118" x 3" x 44-112" Lite-Ply Top Sheet
2 - 118" x 6" x 24" Lite-Ply Bottom Rear Sheeting
2 - 114" x 1-118" x 19" Spreader Bars
HARDWOOD
2 - 112" x 1" x 6" Grooved L.G. Blocks
1 - 1" Triangular x 1-112" Basswood Rudder Mount
,
MUSIC WIRE
1 - 5/32" Dia.
1 - 5/32" Dia.
2 - 5/32" Dia.
1 - 3/32" Dia.
Formed
Formed
Formed
Formed
Front Brace Wire
Rear Brace Wire
Diagonal Brace Wires
Rudder Horn
HARDWARE
4 - Molded Nylon Mounting Brackets
16 - 4-40 x 3/4" Mounting Bolts, for above brackets
16 - 4-40 Blind Nuts, for above bolts
4 - 5/32" I.D. Wheel Collars
4 - Socket Head Set Screws, for above collars
1 - Hex Key Wrench, for above screws
4 - 5/32" I.D. Flat Metal Washers
4 - Molded Nylon Landing Gear Straps
8 - #4 x 112" Sheet Metal Screws, for above straps
1 - 118" a.D. x 1-112" Brass Tube Bearing, for water
rudder
2 - Nylon Washers, for water rudder
1 - Molded Nylon Steering Arm;·Jor water rudder
1 - 3/32" I.D. Wheel Collar, for above steering arm
1 - 4-40 x 3116" Round Head Set Screw, for above collar
1 - 1116" a.D. x 1-112" Aluminum Tube, for cable end
crimpers
1 - .012" x 12 Ft. Roll Braided Steel Cable, for steering
cables
1 - 4" Long Nylon Tube, for cable guides
1 - 10 Ft. Roll Copper Wire, for binding brace wires
MISCELLANEOUS
1 - Full-Size Plan
1 - 16 Page Instruction Book
15
(8.) PRE-FLIGHT
With the floats installed, ready to fly, recheck the balance point of your
model. As mentioned in the introduction, the addition of the floats
shouldn't change the balance of the model very much. It's just a good
,idea to double check before attempting to fly. Don't hesitate to shift your
,.1"lceiver battery or add nose weight if necessary to keep the balance
point where it belongs. Don't try to fly an out-of-balance airplane!
fast enough for the air rudder to become effective, you can steer a little
better. You'll also find that most float planes will turn much better to the
left than they do to the right due to engine torque. Sometimes, if you're
having trouble turning the model to the right to point it in the direction
you want to go, try making a wide left turn all the way around the other
way.
Waterproof your model and radio as much as possible. You'll find that it
is almost impossible to keep all moisture out of your airplane. Water has
a tendency to get inside the smallest openings. However, if you take a
few simple precautions you can usually avoid any serious problems.
First, seCiIany openings in the model as you can, especially on the bottom half of the fuselage where there will be a lot of water spray. Don't try
to seal the pushrod exits, you shouldn't put any bind on them and they
are most likely high enough above the water to avoid being a problem.
Put your receiver and battery pack in plastic bags and seal the bags shut
with rubber bands. These two important pieces of equipment often sit
on the bottom of the fuselage where any water that does get in will
naturally collect. Mount all radio or battery switches inside the fuselage
and actuate them with push/pull wires to the outside. Keep the charging
jack inside the fuselage also. Do not mount your servos against the floor
of the model. Following these few guidelines should provide adequate
waterproofing in most cases.
In spite of all precautions, a wet interior is inevitable at some time. Make
interior checks between flights and at the first sign of any moisture, dry
everything out completely before flying again! If your servos or receiver
get wet, open up the cases, blow them out, and allow to dry thoroughly
before reassembly.
(9.) FLYING
Float flying is fun! It's no more difficult 'than flying off land, just a little
different. If you can successfully fly a model with wheels, you can be just
as successful flying off the water. Some aspects of float flying are a little
.9asier. For instance, most water flying sites are much bigger and flatter
than any model runway. On the other hand, if your engine stops at any
time while you plane is away from shore, it's a lot harder to retrieve the
model, unless you have a boat. For that reason, your engine's idle
reliability is very important! For added security, we recommend that you
install a permanent onboard glow battery(*) in your floatplane to keep
the glow plug lit at idle. Battery systems for this purpose are available
from Ace R/C and other companies.
The best time to fly off water is when the wind is below 10 mph. In higher
winds, taxiing into position for takeoff and back to shore after the flight,
can become very difficult. Simply stated, the "grip" of the floats on the
water is nothing like the grip of wheels to land. Your model will want to
slide or drift across the water with the wind. It will also tend to weathervane into the wind. The floats just won't hold the model from turning as
wheels would do on the ground. Likewise, the water rudder is too small
to hold all of the rest of the model which is above water from turning
when the wind is too high. Sometimes, if you can get your model going
We aren't trying to make it sound like float flying is difficult. Just trying
to explain some of the main differences from land flying. Except while
taxiing, the wind is no more of a factor in float flying than it is in land flying. Experience will quickly teach you how much wind is too much. Below
5-10 mph, the water rudder is effective and you can steer the model at
slow speeds quite effectively. Until you gain some experience, wait for a
relatively calm day tryout your new float plane: For maximum enjoyment, the less wibcjthe better!
Always try to takeoff directly into the wind. Hold full up elevator and
smoothly advance the throttle. Steer straight with the rudder. As the
model accelerates, relax the up elevator and the plane will lift up and
start riding on the step of the floats. The back end of the floats will be
out of the water and the airplane will accelerate even faster. You should
be holding very little, if any, up elevator at this point. When flying speed
is reached pull up slowly on the elevator until the plane lifts off.
Keep your c1imbout and turns gentle until you
model will probably not fly too much different
its wheel landing gear. Just a little bit heavier.
goes on glassy smooth water is pure joy. Good
get to safe altitude. Your
on floats than it did with
Doing endless touch and
luck and happy landings!
)"
-;
PRINTED IN U.S.A.
©SIG MFG. CO., INC. 1985