Page 1
BUILDING
THE
PIPER
J-3
CUB
Page 2
INTRODUCTION
Top Flite is proud to present it's large, scale version of the legendary J-3 PIPER CUB. Few aircraft in the history of aviation have
had the overall appeal of this rugged, good-looking little airplane.
"Cubs" have been used in a wide variety of roles including; trainer, bush plane, ranch work, crop duster, float plane, military and
just for all-around fun. The gentle "lightly-loaded" flying characteristics of the original J-3 Cub have been faithfully reproduced
for you with this kit.
In the "clipped wing" configuration, your Cub takes on a somewhat more acrobatic nature. The
has been the star performer of many an airshow and some of this
country's best-known acrobatic pilots such as Bevo Howard,
Pappy Spinks, Charlie Hillard, Pete Meyers, etc....started their
acrobatic careers in "clipped wing" Cubs.
Our kit offers you the choice of building either the full-span J-3
or the "clipped wing" variant. The only changes needed to build
the "clipped wing" version is to shorten the wing as shown on the
plans and to shorten the length and mounting angle of the struts.
With either version, your Cub will be an outstanding scale model
of the real thing, with flight characteristics to match. When your
Cub is covered with Top Flite's PIPER YELLOW FABRIKOTE.
no additional finishing will be necessary. Even the one piece
molded cowl has been color-coordinated to the FabriKote and it,
too, is ready-to-use without the need of paint. FabriKote will
also give your Cub a tremendous amount of structural integrity
by virtue of it's ability to shrink drum-tight and stay that way.
The construction of the Cub is straight-forward and only requires
attention to both the plans and this instruction manual. Since
the Cub contains so much open structure to duplicate the
original, techniques such as accurate joints and complete glueing
are very important.
full
scale
"clipped
wing"
Cub
The construction sequence in the instruction manual has been
proven to provide quick and accurate assembly. Do not deviate
from the instruction manual. Read through the manual first
while reviewing the plans BEFORE starting actual construction. Often this will clear-up questions that might not be understood during construction.
Our production prototypes of the J-3 Cub used standard frontrotor .40 engines with mufflers. Props used were Top Flite 11 -4
Power Props. Radios were standard 4-channel types with medium
output
servoes.
Flite's PIPER YELLOW FabriKote (see box label). Calculated
data on our prototypes is as follows:
Wing Area
Weight
Wing Loading
Our
airplanes
STANDARD SPAN J-3 "CLIPPED-WING"
795
Sq.
76
Ozs.
13.77 Ozs./Sq. Ft.
Ins.
were
covered
completely
595 Sq. Ins.
72 Ozs.
17.43 Ozs./Sq. Ft.
with
Top
WING
These instructions apply to both the "clipped wing" and full-span
wings. The "clipped wing" version requires that W-1/W-2/W-3
root rib lamination be moved outboard to the position shown on
the plans, sheeting applied like the root section shown, the interplane eyelets be moved outboard on the W-13's and the struts
shortened accordingly. The instructions assume that you will
build both wing panels simultaneously.
GLUE JOINTS
Our prototypes were built using a variety of adhesives - aliphatic
resin, cyanoacrylate and 5—minute epoxy. We recommend that
you use any or all of these as you require.
The tools required to build the Cub are those found in the average
modeler's workshop. You should have a work surface that is large
enough to accomodate an airplane of this size, and it must be flat!
"Beaver board" or Celotex is an excellent surface to work on as
it readily accepts pins. Sharp, single edge razor blades, an X-acto
knife, a power drill and bits, T-pins, a good metal straightedge, soldering iron, hobby saws, sanding blocks and a variety of
sandpaper
When removing the die-cut parts from their sheets, always keep an
X-acto knife handy. Do not force these parts from the sheet, use
the knife to carefully cut on the outline of the part and then
gently remove them. Remove only the parts that you require for
a
particular
needed. Touch-up sand any of the parts that may need it and
always trial-fit the parts in place before glueing, some trimming
may be required. The technique of double glueing all joints,
especially in an airplane of this size is advisable
1
grades
will
be
used
construction sequence,
in
construction.
leave
the others
in
place
until
1. a. Glue wingtip pieces W-16, W-17 and W-18 together and
allow to dry.
b. Glue aileron bellcrank tray supports AT-1 to ribs W-6 and
W-7. Note these parts face each other in the rib bay between ribs W-6 and W-7.
c. Glue the 1/16" thick W-3 (PLY) rib to the inside of the
1/4" balsa W-2 rib. Note there is a right and a left W-2/W-3
laminate, one for each wing panel.
d. Trim the wingtip ends of both 1/4" x 5/8" x 36" main
spars
and
both
1/4" x 3/8" x 36"
plans.
2. Using the 4 pieces of 1/4" x 5/8" x 21" balsa provided, cut 2
aileron spars as shown on the plans — these are 19-3/8" long.
Pin these directly to the plan, between rib location W-4 and
W-9. The 2 remaining pieces will become the aileron leading
edges.
Trim
these
to
19-5/16"
glue, tack glue these pieces directly to the back of the aileron
spar
already
aileron cross-section on plans.)
in
place and secure
rear
spars
as
long. Using a few
with
pins.
(Refer to
shown
"dots"
the
on
of
rib/
Page 3
3. Using the 1/16" x 1/4"
19-5/16" length directly to the rear, bottom of the aileron
leading edge, flat against the plans.
4. Position and pin the bottom 1/16" x 1" x 36" trailing edge
(T.E.) stock to the plans. Note this material ends at the outboard W-12 aileron riblet location — let the excess extend inboard past the W-1. W-2. W-3 location as it will be trimmed
x 36"
cap strip stock provided, glue a
later.
5. Using the 1/16" x 1/4" x 36" cap strip material provided,
measure, cut and glue in place the bottom outboard and inboard aileron cap strips, between the T.E. and the aileron
L.E. cap strip. Note: do not add the other bottom aileron
cap strips at this time.
6. With a razor blade, carefully cut away the T.E. sheeting and
aileron cap strip to accept the 1/16" ply aileron horn plate —
W-19 (PLY). Glue W-19 (PLY) in place.
7. Locate and remove all W-12 aileron riblets from their die cut
sheets. Glue all W-12 riblets in place directly to the aileron
L.E., the aileron L.E. cap strip and the bottom T.E. sheeting,
using the plan for location and spacing. Be sure these are
installed 90° upright and square with plan.
8. Develop Wing Construction Spacing:
a. Pin the bottom, forward 1/8" x 1/4" x 36" sheeting spar
directly to the plans — locate accurately.
b. Directly behind this spar, lay a piece of the 1/16" x 1/4"
x 36"
cap strip stock to serve as the forward rib spacer —
it is not necessary to pin this in place.
c. Directly forward of the aileron spar, lay a piece of the
same
cap
strip
material. This
spacer.
9. Locate and carefully remove all remaining wing ribs from
their die-cut sheets. Carefully remove the die-cut spar cutouts (this is most easily done with the use of an X-acto knife
with a No. 11 blade). "Thread" each rib, in their appropriate
order, over forward 1/4" x 5/8" x 36" main spar and the 1/4"
x 3/8" x 36" rear spar, making sure that the trimmed wingtip
ends of each spar are at the wingtip and are turned up on the
correct side. Space the ribs approximately as shown on the
plans.
10.
Once all the ribs are in place over the plans, the assembly
should be carefully inspected to make sure that each part that
is to contact another, does so. If any trimming is required to
ensure the wing lays flat to the work surface, this is the time
to
do
it.
will
serve
as
the
rear
rib
2
Page 4
11.
Glue the bottom end of each full rib (W-2/W-3 (PLY), and
all W-4's to the 1/16" x 1" x 36" bottom T.E. sheeting. The
outboard W-4 rib is also glued to the inboard end of the
aileron spar, BUT NOT the aileron L.E. Notice the 1/32" resulting gap between the inboard W-12 aileron riblet and the
outboard end of the W-4 rib. This is the correct spacing for
the wing/aileron relationship.
Glue each of the remaining partial ribs (W-5, W-5, W-6, W-7,
W-8 and
on W-6 and W-7 must face each other.
Glue rib W-9 to the outboard end of the aileron spar — not
the aileron L.E.
The W-10 rib is left loose on the spars for the time being.
W-8)
to
the
aileron
spar — remember
that
the
AT-1's
16. Prepare the top forward 1/8" x 1/4" x 36" sheeting spar for
installation by first trial fitting it into place into the rib slots —
relieve any rib slot that might force this spar out of true.
Score the spar just outboard of rib W-9 and lightly "crack" it
downward. Bevel the tip end of the spar to mate flush with
the wingtip as shown on the plans. Glue the spar in place,
into
each
rib
and
to
the
wingtip.
to
dry.
17.
Remove all of the W-11 "false ribs" from their die-cut sheets.
These can now be glued in place onto the 5/16" sq. L.E. and
into the top (only) 1/8" x 1/4" sheeting spar. These ribs
should be aligned with the plans and held securely with pins
until dry.
Secure
with
pins and
allow
12. The wingtip assembly W-16/W-17/W-18 should now be trialfitted in place. Note that this assembly must fit to the very
end of the W-9 rib while the spar slots line-up with the spar
ends and the forward tip piece, W-18, fits against rib W-9
and centered with the L.E. cut-out. At the same time, rib
W-10 must fit into the fore and aft slots provided in the tip
assembly. This is a matter of "fit and try" until you are
satisfied. Once the fit is correct, glue and pin the tip assembly in place as described above. Glue rib W-10 in place in the
slots provided. Allow this assembly to dry completely.
13.
Glue the
against each rib and the cut-out provided in the leading edge
of the wingtip — allow to dry.
14. Using a scrap glue stick, carefully and completely apply glue
(preferably a white glue or an aliphatic resin type) to each
rib/spar
amount of glue but rather to be sure that each joint is completely covered with adhesive, on both sides and top of the
joint.
15. Glue and pin the 3/32" x 1/2" x 36" trailing edge laminate
stock in place on the 1/16" x 1" bottom T.E., directly behind the ends of each rib and aileron riblet. Like the bottom
T.E. sheet, this stock runs from the outboard W-12 riblet, inboard past
trimmed later.
5/16"
joint.
the
sq. x 36"
NOTE:
W-2/W-3
leading
it
is
(PLY)
edge
not
in place. Secure
necessary
ribs.
to
The
firmly
apply a large
excess
will
be
3
18. Use a small sanding block and coarse sandpaper to bevel the
3/32" x 1/2" x 36" T.E. laminate to the shape shown in the
plans. Bevel the laminate only, do not sand into the 1/16"
T.E. bottom sheeting.
19. Glue the 1/16" x 1" x 36" top T.E. sheeting in place. Pin
securely and allow to dry.
20. Prepare the forward wingtip for sheeting by sanding a bevel
into it from the 1/8" x 1/4" top L.E. spar, forward thru the
5/16" sq. L.E., to provide seating for the 1/16" sheeting.
21. Glue and pin the 1/16" balsa top sheeting in place. It is
helpful to lightly score the sheeting just outboard of W-9 to
facilitate the slight compound curve required. Let this
assembly dry completely.
22. Glue all top 1/16" x 1/4" cap strips in place on all ribs, W-12
aileron riblets and W-11 false ribs with the exception of the
W-2/W-3 (PLY) ribs, the inner-most W-11 false rib and the
first inboard W-4 rib. This section will be sheeted later.
Page 5
23.
Locate and remove the 1/16" thick W-19A (PLY) horn plate
doublers from their die-cut sheet. Glue in place on top of
horn plate W-19 (PLY), as shown on the plans. Locate and
remove 4 of the G-2, 3/32" balsa gussets and glue these in
place into each corner of each aileron as shown on the plans.
24.
Using a small sanding block and medium-to-coarse sandpaper,
lightly sand the protruding tops of the aileron spar and aileron
L.E. stock down to the airfoil level of the wing. These should
blend with the cap strips to create the finished airfoil (refer
to wing/aileron cross-section on the plans).
25.
Prepare the aileron bellcrank mounting trays W-20 (PLY) by
first drilling them per the dimensions given on the plans with
a No. 45 (.082") drill bit. Mount the 90° aileron bellcranks
to the trays as shown on the plans. These should work freely
but without "slop". Epoxy the trays into place on the AT-1
supports in the W-6/W-7 rib
bay.
26. Remove wing panels from the building board. Inspect each
panel carefully to be sure of good glue joints, etc. Now is the
time to clean-up each panel to prepare them for finishing.
Glue all the remaining gussets, G-1, G-2 and G-3 in place as
shown.
27. Carefully block-up each panel upside down on the building
board. Be sure that the panels are firmly pinned and blocked
in place and that they are truly flat. Prepare the bottom for-
ward 1/8" x 1/4" x 36" sheeting spar by first trial fitting it in
place into the slots in the ribs. Relieve any rib slot that might
force this spar out of true. Score the spar just outboard of
rib W-9 and lightly crack it. Bevel the tip end of the spar to
fit flush with the wingtip, as shown on the plans and glue the
spar into place. Secure with pins and allow to dry.
4
Page 6
28.
Using a sanding block, bevel the wingtip from the 1/8" x
1/4" sheeting spar, forward thru the 5/16" sq. L.E. to provide seating for the 1/16" balsa L.E. bottom sheeting. Glue
and pin the L.E. sheet in place. Note that it is advisable to
lightly score the sheeting just outboard of the W-9 rib to
facilitate the slight compound curve required. Let this
assembly dry.
29.
Locate and glue 1/16" thick parts W-15 (PLY), W-14 (PLY)
and both W-13 (PLY)'s in place per the plan. NOTE: be sure
to glue the W-15 (PLY) parts in place correctly to provide
exit of the threaded aileron pushrods from the bellcrank end.
TAIL SURFACES
Accurate joints, complete glueing and a flat work surface are
essential to strong tail surfaces. Cover stabilizer and rudder area
of plan sheet 1 with Monokote backing material or Saran Wrap
before beginning construction of these parts.
STABILIZER
1. Glue and pin in place all die-cut S-1's, S-2's, S-3 , S-4's and
the 1/4" x 1/2" balsa trailing edge. Using the 3/32" x 1/4"
stock
provided,
not glue the 1/8" x 1/2" gussets in place yet.
cut
to
size
and glue
in
place
the
"ribs".
Do
30.
Using the 1/16" balsa sheet provided, sheet the wing root
from the inboard W-4 rib thru the W-2/W-3 (PLY) rib noting
grain direction on plans. Glue all remaining wing and aileron
cap strips in place and allow to dry.
31.
Remove the wing panels from the work surface. As before,
inspect them, remove any glue runs and make sure all joints
are properly glued. The panels can now be lightly sanded to
final shape with the exception of rounding the leading edges
to final shape. This will be done later. Locate and glue the
1/16" thick ply strut plate doublers W-15A (PLY) and W-14A
(PLY) in place on top of W-14 (PLY) and W-15 (PLY).
ELEVATORS
1. Glue and pin in place all die-cut E-1's, E-2's, E-3's, E-4's and
the 1/4" x 1/2" leading and trailing edges from the stock
provided.
Cut off a 3" length of 1/4" diameter dowel and epoxy in
place between the two elevator halves as shown on the plans.
2. When the stabilizer and elevator assemblies have dried, remove
them from the work surface. Inspect and clean-up each of the
glue joints. Using the 1/8" x 1/2" stock provided, carefully
make and install each of the gusset joint reinforcements, as
shown on the plans. Fit these to each joint, noting grain
direction and center them between the upper and lower
Cut
and glue
in
place
the
3/32" x 1/4" "ribs".
surfaces.
FIN
1. Glue and pin in place die-cut parts R-1, R-4 and the 1/4"
x 1/2" outline stock. Note on the plans that the bottom,
trailing edge piece of 1/4" x 1/2" wood has an "extension"
cut
into
it's
shape. This
Also note that 1/4" square balsa is used at the top of the fin
to complete it's outline. Glue the 3/32" x 1/4" "ribs" in
place.
area
is
shown
as
cross-hatched
(////).
32. Use a razor or hobby saw to remove the excess sheeting, L.E.,
T.E. and spar stock from the root of each wing panel.
LIGHTLY sand the balance of this material flush with the
face of root rib W-2. Be careful to sand ONLY to the face of
this rib, not into it.
With a few exceptions,
ceed to the next construction phase of these instructions.
your
wing panels are now complete. Pro-
5
Page 7
RUDDER
1. Glue and pin in place die-cut parts R-2, R-3 and the 1/4" x
1/2" outline stock. As with the fin, note the piece of 1/4"
sq. stock used to complete the outline, just above the top of
the fin. Glue the 3/32" x 1/4" "ribs" in place.
2. When the fin and rudder assemblies are dry, remove them
from the work surface. Inspect and clean-up the joints. Like
the stabilizer and elevator assemblies, install the gussets,
centered between the outside surfaces.
Use a sanding block to sand the tail surfaces to the final outline
shape shown on the plans. Sand the surfaces to remove any high
spots. Finally, sand the final rounded cross-section shapes of each
surface. Note that the R-1 piece on the front of the fin must
blend into the 3/16" diameter dowel used for the "spine" stringer
on the fuselage. Each surface should now be slotted for hinges
and set aside for covering and assembly.
FUSELAGE CONSTRUCTION SEQUENCE
Carefully position and tape plan sheets No.'s 1 and 2 together,
using
the
dashed
one over the other to assure uniformity. These two sides are
identical except
built into it. The instructions take this into consideration. To
further insure uniformity we advise that two each of brace, up-
right and longeron be cut at the same time, when building the
first side. Cover plan with Monokote backing or Saran Wrap
before starting.
lines.
that
the
The
right
two
side
fuselage
will
have
sides
the lower
will
be
constructed
access
door
1. Start the right side by pinning and glueing the two-piece 1/4"
square upper balsa longeron in place. The forward piece is
from the front of the firewall to F-11 position. The rear
piece is from F-11 to rudder hinge line.
2. Pin and glue the three piece 1/4" square lower longeron in
place. The forward piece is from the front of the firewall to
the center of front landing gear block. The center piece from
the center of front L.G. block to center of rear L.G. block.
The rear piece runs from the center of the rear L.G. block
back to the rudder hinge line.
3. Using the 1/4" square and 1/8" x 1/4" balsa provided,
accurately cut, glue and pin all uprights in place. Note that
the front, bottom and rear 1/4" square door outline should
not be glued to the 1/4" square door frame. Maintain a
slight gap all the way around the frame as the door will be
cut free later. Also note that the forward-most nose upright
is recessed back 1/4" to allow the firewall to key in place.
With the 1/4" x 3" x 12" balsa provided, measure, cut and
glue the fillers into the front of the fuselage.
4. Allow to dry and remove pins. With a sanding block, lightly
smooth the frame. Cover frame with Monokote backing or
Saran Wrap and repeat steps 1, 2 and 3 — deleting the door
outline, building the left frame directly over the right one.
5. When dry remove both frames from the work surfaces. Inspect
and clean-up the joints. We suggest double-glueing these
joints. Lay the sides back over the plans and with a soft
pencil, mark the location of formers F-2, F-10 (mark the
location of this former on the INSIDE of each frame), F-11,
F-4, F-5, F-6, F-7, F-8 and F-9. Last, mark the location of
the 1/8" x 1/4" tank shelf supports at the nose.
6. Sand a shallow joining taper into the inside of each fuselage
at the tailpost. Remember the right fuselage side has the door.
This taper should result in the tailpost of each frame measuring 1/8" in width, 1/4" when held together.
7. With the 1/8" balsa sheet provided, cut four 17-3/4" lengths.
Using a flat surface, "butt-glue" two pieces together to form
a rough fuselage side, which should then measure 1/8" x 6" x
17-3/4". Repeat this step with the remaining two pieces.
6
Page 8
Cut two fuselage sides. Note that at the furthest aft point the
fuselage side ends at F-4 on the top and angles forward to the
bottom
as
shown on
past the first upright to the ends of the top and bottom longeron. The firewall fits inside of the fuselage sides.
With the fuselage side frames laying face down on the work
surface, remember that the right side contains the door, glue
the 1/8" sheet fuselage sides to the right and left fuselage
frames. Pin in place. Glue die-cut pushrod exit sheets F-23R
(for right side) and F-23L at the end of each fuselage frame.
Pin in place. Glue the 1/8" square top longeron doubler in
place between the end of the fuselage side and the front edges
of F-23R and F-23L. Locate position of, and glue the
"center"
between fuselage sheeting and F-23R and F-23L.
When the fuselage side assemblies are dry, place them accurately together and sand their edges with a sanding block to
assure uniformity.
With a hobby saw or a razor blade, score the longerons of
each fuselage side just behind the second 1/4" square upright, both the top and bottom. Turn the fuselage sides over
and score the 1/8" sheeting along the same line represented
by the back edge of the second fuselage upright. Do not cut
all the way through but enough to allow the fuselage sides to
be "cracked" inward along the scored lines. Place the fuselage sides down on the edge of a table, longeron side down,
with the scored line just above the table edge. Carefully
press down on the section ahead of the scored line and crack
it. Do the same for the opposite fuselage side.
8. Glue F-5A to F-5B to form former F-5. Glue all 1/8" x
1/4" braces to F-5, F-6, F-7, F-8 and F-9. Allow to dry.
Cover bottom view of plans with Monokote backing or Saran
Wrap. Carefully cut, glue and pin all bottom 1/4" square
and 1/8" x 1/4" cross-pieces and diagonals over plan.
Position
down and the widest area of the block toward the rear.
Secure with pins.
1/8"
rear landing
the
plans.
square stringer in
gear
block
At
the nose, the
place
along
over plan
with
sides
fuselage
the
slot
extend
framing
facing
7
9. Pin
and glue the right and left fuselage sides over the plans
and to the cross-pieces, diagonals, the rear landing gear block
and to each other at the rear tail-post. Use a triangle to keep
the sides at 90° to the work surface.
Glue, position and pin formers F-4 (PLY), F-5, F-6, F-7, F-8
and F-9 to top rear of fuselage sides using the pencil marks
made earlier for location. NOTE: these formers do not sit at
90° to the top of the fuselage longerons, they "lean" slightly
toward the rear of the fuselage as shown on the plans. Allow
glue to dry.
Bevel the ends of the forward landing gear block to match
those shown on the plans. Glue forward landing gear block
in
place,
slot
down.
Note
that
the
edges
of
this
block
will
beveled later to match the fuselage bottom.
Trim notches of former F-3 slightly to allow it to sit at the
angle shown on the plans. Glue former F-3 in place.
Trial-fit former F-11 (PLY) in place, referring to Section D-D
on plans. F-11 (PLY) must fit between the two 1/4" square
uprights in this section and directly on top of the 1/4" square
top longerons. Trim if necessary to fit and epoxy in place,
centered on the uprights.
Using the location marks made earlier, trial-fit forward former
F-10 (PLY) in place. Note that the installation of F-10
(PLY) requires that the bottom nose area of the fuselage be
pulled in slightly. Glue the 1/8" x 1/4" tank supports in
place using earlier marks. Epoxy F-10 (PLY) in place and
secure
with
tape
until dry.
Glue F-19 stabilizer supports in place at the rear of the fuse-
lage. They glue to the top of the longerons, against F-9 with
the outer surface flush with the top 1/8" stringer —
Sections J-J and K-K on plans.
Cut and glue 1/4" square nose cross braces in place between
top and bottom longerons. Glue the last two nose formers
F-1 and F-2 in place. Glue the top center length of 1/8" x
1/4" stringer in place in slots in F-1, F-2 and F-3.
When dry, remove fuselage from the building surface, inspect
joints, clean them up as required, double glue if necessary
and proceed to next step.
be
see
Page 9
10.
NOTE: This
engine to the right side as shown on the plans.
Carefully cut-out the firewall template provided on plan
sheet No. 2 and lightly glue it to the 1/4" plywood firewall.
Drill four 3/16" diameter holes in the firewall using the template as a guide. Using the No. 4-40 x 5/8" bolts and the
No. 4-40 blind mounting nuts provided, install the motor
mount to the firewall. Tighten the bolts enough to force the
blind nuts into the back of the firewall. Carefully remove
the bolts and epoxy the blind nuts to the back of the firewall — DO NOT get any epoxy into the holes of the nuts but
apply epoxy around the edges to retain them in place.
step
assumes
that
you
will
be
mounting your
Epoxy both F-12 (PLY) forward landing gear block supports
in place on the inside of the fuselage. Also epoxy both F-13
(PLY) rear supports in place.
Using two 5" lengths of the 1/4" x 3" x 24" balsa provided,
cover the bottom of the nose area from the forward landing
gear block to firewall — see side view. Trim the excess flush
with
the outer
With the 3/32" sheet provided, plank the top nose area from
F-3 forward to firewall. This is done with two pieces with
the joining seam on top of the 1/8" x 1/4" balsa stringer.
Sand flush with rear face of F-3 and front of firewall.
fuselage
sides.
MOTOR MOUNT
Trial-fit the
note that it will be necessary to slightly relieve the top fuselage
cross-brace and the face of F-1 to allow the firewall to fit
flush. It may also be necessary to trim the firewall slightly to
fit properly.
Using the remainder of the 1/8" sheeting used for the fuse-
lage
sides,
grained as shown on the plans, to become the fuel tank tray.
This is most easily done by making one piece to fit ahead of
F-10 (PLY) and a second to fit behind it. DO NOT cut into
F-10 (PLY) to fit these pieces. Work around it. Glue the
tank tray pieces in place on the 1/8" x 1/4" supports.
Epoxy firewall in place against uprights, cross-braces, F-1 and
tank tray.
11.
Fit and glue 1/4" die-cut bottom nose sheet F-18 in place.
This part fits flush with the bottom longerons. With the remaining 1/8" sheet balsa, fill in the bottom of the fuselage.
cross-grained, from the back of F-18 to the front landing
gear block, between the front and rear landing gear blocks
and from the rear landing gear block to the first 1/4" square
bottom cross-brace. This sheeting fits flush with the bottom
longerons.
firewall
cut,
trim
into
and
the
fit
nose
two
of
the
pieces
fuselage.
of
this stock,
You
will
cross-
12.
Carefully remove the two plywood cabin frames, F-14 (PLY)
and F-15 (PLY), from their die-cut sheets. Remove the
window cut-outs from the frames. Note that F-14 (PLY) is
the right side cabin frame as it contains the upper door half.
Remove this door section from F-14 (PLY) and set it aside
along with the window cut-outs. Clean-up all of the inside
window frame
edges
with a sanding
block
as
required.
8
Page 10
Epoxy F-14 (PLY) and F-15 (PLY) in place, on top of the
fuselage longerons, against formers F-10 (PLY), F-11 (PLY)
and F-4 (PLY) and keyed into the tabs on F-10 (PLY) and
F-11 (PLY). Tape this assembly securely in place and allow
glue to dry completely.
Laminate and glue F-17 (PLY) to F-16 (1/4" balsa). Make a
similar second part but make it just the opposite so that you
have a right and left F-16/F-17 (PLY) assembly.
Glue these two assemblies in place against the insides of F-14
(PLY) and F-15 (PLY) with the F-17 (PLY) facing each other
in the cabin. Align and firmly clamp these assemblies until
completely dry.
13.
With
the
1/16"
sheet
balsa
provided,
that sits on the fuselage top longerons just in front of F-4
(PLY). Glue in place.
cut
and
fit
the
"shelf"
With the 1/4" balsa sheet provided, accurately measure, cut
and fit the top cabin sheeting in place from the back of F-10
(PLY) to the front of F-4 (PLY). Note cross-grain direction.
THE PIECES MUST FIT ACCURATELY TO ACHIEVE
THE MAXIMUM STRENGTH. Once satisfied with the fit,
epoxy these parts in place and allow to dry.
Carefully trim and fit the triangular cross-piece block that
sits on the front of F-10 (PLY) and between the F-14 (PLY)
and F-15 (PLY) cabin sides — see side view. Glue this block
in place. Next, we have provided one block with two radiused
ends. Using the top view on plan sheet No. 2, cut two top
forward wing blocks. Epoxy these two blocks in place against
the triangular block and F-14 (PLY) and F-15 (PLY). They
will be final shaped later.
14. Use a piece of scrap 1/4" sheet to rest on top of the two
F-19 stabilizer supports, to fill the stabilizer slot. Trial-fit
the fin in place as shown on the plans. Note that when
properly in place, R-1 contacts F-9 and the trailing edge of
the fin lines up with vertical end of the fuselage. Once satisfied, glue the fin in place against F-9 at the front and at the
rear, the small cross-hatched area of the fin trailing edge on
top of the F-19's (see side view of plans). Use pins and tape
to
assure
the
fin
is
truly
vertical
dry completely.
to
the
fuselage.
Allow
to
Frame the left cabin side F-15 (PLY) windows with 1/8" x
1/4" stock provided. The 1/8" side fits against the plywood.
On the left side only the area on top of the fuselage longeron
from F-10 (PLY) to F-11 (PLY) and the two upright window
frames receive this material. On the right side, F-14 (PLY),
the upper door receives the same treatment except that it is
completely framed around its perimeter as well as the two
upright window frames.
9
Page 11
Remove the 1/4" die-cut F-21 fin supports from their sheet.
Note that these fit in place in the notches provided on each
side of F-9, back to the trailing edges of the fin. Bevel the
inside
edge
of
each
F-21
to
fit
flush
with
the
fin
and glue
place. Allow to dry.
15. Note that notches have been provided in all formers from
F-4 (PLY) thru F-9. These are to support the three 3/16"
dia. stringer dowels. The two side dowels are to blend
smoothly with F-21 at the tail. The center dowel is to blend
with the roof line as shown on the top view of the plans and
at
the
tail
it
"carries
trim the dowels as required. Fit them in place, relieving any
former that might force them out of true. Glue dowels in
place and
filler from the stabilizer slot.
Using a sanding block and medium paper, sand the F-19, F-21
and the stringer dowels to the cross-section shapes shown on
the plans.
16.
Trim F-22 (PLY) tailwheel mount to fit inside of the tail-
wheel bracket. As shown on the plans, epoxy a wedge of
1/4" balsa to F-22 (PLY), sand to shape and epoxy to the
bottom of the fuselage at the tailpost. When dry, mount the
tailwheel
screws provided. Do not overtighten screws. Bend the tailwheel wire to the shape shown WITHOUT the "L" bend at
the top. Insert the wire into the nylon bracket and then
bend the 90° "L" bend that goes into the rudder. Drill a
pilot
provided and epoxy this tube in place. Make a slot below
the tubing to clear the tailwheel wire in the rudder. Remove
the tailwheel assembly from the fuselage.
hole
secure
bracket
in
the
with
to
the
rudder
thru"
the
tape
until
F-22 (PLY)
for
the
fin
shape at
dry.
Remove
base
small length
R-1.
the
with
of
Sand and
1/4"
scrap
the
No.
brass
tube
2
in
LANDING GEAR
Note that the landing gear wires have been essentially pre-bent to
shape. It may be necessary to slightly correct some of these
bends during assembly with pliers or a vise. Take the time to be
sure that these wires fit well with one another. Before assembly,
clean
off
the
wires
with a degreasing
tone, etc. A good technique is to sand these wires with No. 400
sandpaper around the areas that are to be soldered before assembly.
1. Turn the fuselage over on it's back and position the front L.G.
wire (1/8" dia.) into the forward landing gear block. Be sure
it is centered from side to side. Position the rear landing gear
wire — also 1/8" dia. — into the rear L.G. block. Using the
plans for reference, fit the rear wire to the forward one at the
axles and temporarily hold in place with a small piece of tape.
Now fit the LOWER 3/32" diameter cross-brace wire in place
and correct as needed for proper fit. Carefully wrap the
three wires together at each axle as shown, with soft copper
wire. Solder these joints.
2.
With
the
landing
two 3/32" dia. top joining wires in place as shown. Wrap the
joints carefully with wire and apply just enough solder to each
of the four joints to keep the wires from shifting. Carefully
remove the landing gear assembly from the fuselage and complete the soldering of these joints.
gear
still
agent, such
in
place on
the
as
alcohol,
fuselage,
ace-
fit
the
17.
Sand entire fuselage to final shape. Take this time to inspect
joints, double-glue as needed. Do any filling that might be
required. The shaped blocks ahead of the cabin carry thru
the leading edge shape of the wing. It is advised that these be
rough-carved to shape and final sanded only when the wing
panels are mounted to the fuselage.
18. If you are planning to install a top observation window over
the cabin (window material not supplied), take the measurements for its size and location from the plans and cut it out
of the 1/4" cabin sheet. Our prototypes used .020" butyrate
for this detail.
3. Fit the top cross-brace wire in place, directly over the lower
wire. They should line-up when viewing from the side. Wrap
the two joints required with soft wire and solder.
10
Page 12
4. Clean-up each of the solder joints with a wire brush and make
sure that the joints are strong. With the 1/4" sheet provided,
make two inserts to fill the triangle created by the front and
rear main wires. Epoxy these in place, centering them on the
front and rear wires. When dry, sand them to shape using the
front
and rear wires
your
wheels
nished). Cut off the excess axle wire and except for covering
the fillers, the landing gear is ready for use.
5. Again place the landing gear assembly on the fuselage. Locate and drill 1/16" guide holes for the four metal landing
gear clips (see plan for position). Leave the landing gear in
position and make the two wing strut supports as shown on
the plans from the material provided. With the two rear landing gear clips in position, drill the guide holes for these supports. Remove all hardware from the fuselage and set aside
for final assembly.
in
as
the
place and
"leading
secure
with
and
wheel
trailing"
collars
edges.
(not
FINAL ASSEMBLY
1. Remove both W-1 (PLY) "cap" ribs from their sheet. Re-
move the four (4) holes stamped on their surface. An X-acto
knife does this best. Accurately tack-glue these two ribs to-
gether. Use a sanding block to "match" their outlines — they
must be identical. Use a 1/4" dia. drill bit to "match" the
four holes. These too, must be the same. Once satisfied,
separate
sanding block.
2. Tack-glue each W-1 (PLY) to each side of the fuselage,
matching the top of the rib to the same edge as the cabin.
This must be accurate to insure proper wing/fuselage mat-
ing. "Eyeball" the two holes at each end of the W-1 (PLY)'s
to
will
Use an electric drill and a 1/4" dia. bit to drill the four holes
into each fuselage side, using the W-1 (PLY)'s as a template.
NOTE:
and all the way through the inner F-17 (PLY)'s. Use a pencil
to mark the left W-1 (PLY) "L" and the right one "R". Re-
move them from the fuselage.
3. Cut two 6-1/4" lengths of 1/4" dia. dowel provided. Slightly
round their ends and insert them in place through the fuselage. Center them as shown on the plans. These are the for-
ward and aft wing panel supports and will NOT be epoxied in
place
for now for positioning wing panels.
4. Thread the outer nyrod tube through the wing ribs to just
inside the W-6 rib as shown on the plans. Leave the excess
sticking out of the root rib W-2. Epoxy these tubes in place
on each rib. Make the "L-bend" linkage for the inner nyrod
tube to connect the 90° bellcrank to the inner pushrod.
5.
Drill
ing nuts (No. 4-40 provided) into W-14A (PLY) and W-15A
(PLY), as shown on the plans. Drill holes for the interplane
strut eyelets in the W-13 (PLY)'s. DO NOT glue eyelets in
place until after the wings are covered.
6. Place the wing panels on a FLAT surface, using weights to
keep them that way. Epoxy the W-1 (PLY) "cap" rib, that
you makred "L", to the left wing panel root, over the nyrod
tube and flat against W-2 rib. Both the W-1 (PLY) rib and the
wing panel must be flat against a common surface for alignment. Repeat this step with the right panel. When these
assemblies are dry, use the drill and 1/4" bit to drill all four
holes in W-1 (PLY) through the wing root W-2/W-3(PLY) laminate. Like the fuselage, drill these holes at accurate right
angles to the wing root surface.
11
the
two
ribs and clean
be
sure
that
the
1/4"
clear
F-10 (PLY) and F-11 (PLY)
drill
these
holes at
until
after
the
fuselage
holes
for,
and
press
dowel
in
place,
right
is
off
any
dried
holes
you
are
as
shown on
angles
to
the
covered. Leave
the
wing
strut
glue
about
the
fuselage
them
blind
Slip
fur-
with
to
drill
plans.
sides
in
place
mount-
a
7. Slightly enlarge the hole in the W-1 (PLY)/W-2/W-3 (PLY)
wing roots to accept the outer diameter of the 1/4"-20 blind
mounting
Epoxy these nuts in place as shown on the plans. Keep epoxy
away from the threads, but use enough to keep the nut from
coming loose.
8. With the 1/16" balsa sheet provided, cover the top center
section of each wing panel and allow to dry. Trim the excess
outer nyrod tube flush with W-1 (PLY).
9. Join the two wing panels together on the work surface using
some scrap 1/4" dia. dowels at the W-1 (PLY)'s for alignment.
Use a sanding block to final sand the leading edges to the
finished shape. Once satisfied that the panels have the same
leading edge shape, sand the rest of the panels to final shape,
including the wing tips.
10. Drill the 1/16" guide holes in each aileron horn mounting
plate, W-19 (PLY). Mount aileron horns with No. 2 screws
provided. As shown on the plans, bend to correct length and
install the aileron pushrod — provided — to the 90° aileron
bellcrank. Since the ailerons have not yet been cut free from
the wing, neutral is easy to achieve. Turn the wing panels over
and epoxy the bellcrank nut to the bellcrank tray W-20 (PLY).
Remove the aileron horns from the ailerons and set aside for
assembly after covering.
11. Carefully cut ailerons free from wing at the inboard trailing
edge. Break free the tack-glued joint between the aileron
spar and the aileron leading edge. Lightly sand the leading
edge of each aileron to the cross-section shown in Section
B-B on the plans, using a flat sanding block and medium
paper. Cut the hinge slots in each wing panel and aileron and
trial-fit. The ailerons and panels are now ready for covering.
12. The bottom door on the right side of the fuselage can now be
cut free. Pin holes made from the inside at each corner of
the door between the 1/4" square frames will mark it's location accurately. Once the door is free from the fuselage, use
a sanding block to smooth it's edges. Set aside for covering.
13. Remove the 1/4" spacer that is between the F-19 and F-21
pieces at the tail of the fuselage. When the fuselage and fin
are covered, remove the material from around the stabilizer
slot and cut-away the small piece of wood at the tailpostto
facilitate installing the stabilizer. The stabilizer should be
first covered separately, trial-fitted in place and then have the
fabric removed from the center-section where it contacts the
upper F-21's and
Only then should it be glued in place. Then the covered elevators are hinged to the stabilizer followed by hingeing the
covered rudder over the tailwheel steering wire to the fin.
14.
The
tional
the nylon 1/4"-20 wing attach bolts. Therefore provisions for
hingeing these doors
place should now be considered. On plan sheet No. 2 we show
a scale-like method of being able to open and lock these two
doors. This is the method we used on our prototype and it
works well. We hinged our doors with regular model aircraft
hinges. If this method does not appeal to you, we suggest
hingeing the doors with yellow Super Monokote strips and
using tape or Trim Monokote at the center to keep the doors
closed.
15. The aileron, rudder and elevator servos should now be in-
stalled. The installation shown on the plans is exactly what
we used on our prototypes and works very well. Install the
rudder and elevator nyrods as shown. Be sure to anchor the
outer nyrods in place at various points in the fuselage to pre-
nut
top
and
bottom
and provide
that
will
lower
access
access
as
serve
F-19's
to
well
as
the
wing
to
create a good glue
doors
are
meant
the
radio
equipment
as
being able
bolt
to
to
be
"lock"
attach
fully
as
point.
joint.
func-
well
them
as
in
Page 13
vent "snaking". The location of the rudder and elevator
horns should be established, the holes drilled but not installed
until
after covering. The aileron
to the manufacturer's aileron servo tray. The tray is then
mounted to a 1/16" plywood plate that has been cut to size.
The plate is then epoxied in the correct position to the inside
roof of the cabin. The flexible inner nyrod ends that connect
the ailerons to the servo can accomodate virtually any servo
type
and
output
tion works smoothly before covering. The throttle servo is
installed after the plane is covered and the engine installed.
arm
available.
servo
Make
should
sure
be
the
first
servo
mounted
installa-
STRUTS
IMPORTANT NOTE: THE WING STRUTS ON YOUR J-3 CUB
ARE FULLY FUNCTIONAL AND ARE ABSOLUTELY REQUIRED FOR FLIGHT. THEIR ASSEMBLY, FIT AND ATTACHMENT ARE CRITICAL. DO NOT DEVIATE FROM ANY OF
THE FOLLOWING INSTRUCTIONS:
1. The wing struts provided (4) are 9/32" x 11/16" x 27" hardwood, preshaped. Very little sanding should be required to
smooth their surface. Extra length has been provided to allow
a mistake or two achieving the correct angles. Beveling these
parts to fit flush with the bottom of the wing is important
and should be done carefully. Note that none of the wing
struts are interchangeable. There must be a left-front, left-
rear, right-front and right-rear. In order to avoid confusion it
is suggested that you make a front and rear strut for one
panel, mark them as such, set them aside and proceed to the
opposite set.
2. Start by assembling the right and left wing panels to the fuselage and securing with the 1/4"-20 nylon bolts provided. Attach the brass strut plates to the bottom of the fuselage as
shown on the plans. Set the assembled airplane upside down
on a flat surface — linoleoum floors work well — with a 1/4"
spacer between the top of the fuselage and the flat surface.
This will impart a slight amount of dihedral to the wings as
in
the
full
scale
Cub.
3. As mentioned in No. 1 above, start with either the right or
left side, beginning with the FORWARD strut. Prop up one
strut, on edge, directly over the front view of the wing/strut
joint on plan sheet No. 2. Remember there is a left and right
strut. Using a razor saw, carefully saw off the end of the
strut at the angle shown on the plans. Next, take this strut
over to your inverted model and, holding the cut angle against
the forward outboard strut plate, make sure that the inboard
end of the strut is at approximately the right location to encounter the brass strut plate. Note that the strut at this
point is too long. It will be cut to length shortly. If the
angle at the end of the strut is not quite right, use a sanding
block to bring it to true. Using a 7/64" dia. drill bit, drill
the outboard strut-attach hole through the end of the strut
as shown on the plans, at a right angle to the bottom of the
wing. This hole is for clearance of the No. 4-40 machine
screw that mounts the strut to the wing. Slip one of the
No. 4-40 machine screws provided through the hole you've
just drilled and into the blind mounting nut in the wing.
Tighten this screw just enough to create an impression of the
screw head in the wood. Remove the screw. With a grinder,
knife or
to allow the head of the screw to sit flush to the wood when
in place. As shown on the plans, epoxy one of the No. 4
steel washers provided, to the strut, over the attach-hole.
When dry, attach the strut to the wing.
4. The inboard end of the strut is simply cut to lenth as shown
on the plans. Remove the strut from the wing. With a 1/16"
dia. drill bit, drill the guide hole for the No. 2-56 x 1"
sanding
block,
create a small
"flat"
around
the
hole
threaded stud that is to be tapped 1/2" into the inboard end
of the strut. Do not drill this hole any deeper than 9/16".
Tape off 1/2" of the No. 2-56 x 1" stud with masking tape,
dip the exposed end into 5-minute epoxy and "screw" this
end into the hole in the end of the strut to the depth of the
masking tape. Pliers can be used to hold the stud during this
operation. Wipe off any excess epoxy. Remove tape and
allow
to
dry.
Thread one
exposed end of the stud and attach to the brass plate, in the
forward hole. Reattach the strut to the wing and fuselage
and proceed
cedure as above. Note that rear inboard end of the forward
strut must be trimmed as is shown on the plans to allow the
rear strut to fit closely to it.
5. The "interplane" struts are made from the two pieces of
.072" dia. x 12" wire provided. Their shape is depicted on
plan sheet No. 3, in Section A-A. Note: do not bend these
to shape until the two nylon mounting clips are first slipped
in place with their ends facing inboard, toward the fuselage
and flat against the front and rear struts. The ends of the
interplate strut fit into the eyelets provided in the wing. Note
that in the front view, the interplane struts exit the wing at
right angles to the bottom of the wing and are held in place
by the
No. 2 x 1/4" wood screws provided also. The ends of these
struts ride free in the eyelets for removal.
6. We strongly recommend that you cover your struts with Fabrikote. This will further strengthen these struts and, if you
are using Fabrikote to cover the rest of your Cub, they will
be color coordinated and ready to use. If you are planning
to use any other covering, we recommend that you fiberglass
the struts and paint to match.
nylon
to
make the
fittings
which
of
rear
are
the
clevises
strut.
attached
provided
Follow the
to
the
spars
onto
same
with
the
pro-
the
COVERING AND FINISH
The full-scale J-3 Cub is almost completely fabric covered. This
covering kept the weight down and added strength. Your Cub,
being an accurate scale model not just in outline but in construc-
tion
sense
as
well,
requires
FABRIKOTE is the perfect covering material for your Cub. It is
extremely light, woven aircraft fabric that is very strong and is
pre-finished and ready-to-use. The PIPER YELLOW color in
FABRIKOTE will yield a perfectly finished J-3 PIPER CUB. On
plan sheet No. 1 you will find the Fabrikote cutting layout. Note
that this layout is approximate and your covering techniques may
increase or decrease some of the dimensions shown.
All of the individual parts of our prototypes were covered separate-
ly; ailerons, doors, stabilizer, rudder, elevators, struts, wing panels
and the fuselage. Only after covering did we hinge the surfaces,
add the windshield and windows, the window support dowels
(3/16" dia. provided), install the cowling and add any of the
tails.
The one piece cowl is matched to the Fabrikote PIPER YELLOW
color and requires no additional finishing.
the cowl we suggest using an epoxy-type paint, color mixed to
match, after first sanding with No. 600 paper, wet. Note that we
have provided an accurate, correct scale 3-view drawing of the 4
cylinder Lycoming engine used in many of the full scale Cubs.
These details can
craftsmanship.
The 3-sheet set of mylar decals will complete your Cub.
cation for these decals are called-out on the plan sheets.
Be sure to give the firewall area of the fuselage a liberal coat of
polyester resin or epoxy glue to fuel proof it and to seal the nose.
Be careful not to get any resin or glue into the cowl mounting
block screw holes.
be
the
same
considerations.
added using plastic,
If
you wish to paint
metal,
wood
Top
Flite's
and a little
The
de-
lo-
12
Page 14
If, for any reason, you choose not to use Fabrikote for covering
your Cub, we recommend that you use some kind of fabric covering, such as silk and dope. CLOTH COVERING IS RECOM-
MENDED ON THIS MODEL.
ENGINE AND COWL MOUNTING
1. Use a few drops of cyanoacrylate glue to mount your engine
temporarily to the motor mount, in the approximate position
shown on the plans. Turn the fuselage so that the firewall is
pointing straight up. Set the engine and mount on the firewall
about where it is shown on the plans, except turn the cylinder head of the engine so that it is inverted instead of sidemounted. Slip the cowl over the engine and on the fuselage.
On some types of engines, it may be necessary to remove the
needle valve.
If the engine is sticking too far out of the cowl opening or is
not sticking out far enough, remove the cowl and reposition
the engine on the mount to correct. Once you have the
engine on the mount where you want it and the cowl down
over the nose of the fuselage where it will finally fit, remove
the cowl and use the engine's position on the mount to mark
hole locations for mounting the engine to the motor mount.
Remove the engine.
2. The typical .40 engine requires the use of No. 4 x 5/8" sheet
metal screws (not furnished) to mount the engine to the
motor mount. Use a 3/32" dia. drill bit and accurately drill
the motor mount with four guide holes. Next it will be
necessary to pre-tap these holes with a No. 4 x 5/8" sheet
metal screw. Use some oil on the screw and in the holes to
assist in the thread cutting.
3. Bolt the motor mount, without engine, in place on the firewall. If you are using a muffler, attach it to the engine at this
time
along
with
the
needle
might be left off. Using the plans as a rough guide, CARE-
FULLY begin to cut-out the right side of the cowl. The use
of a hand held grinder is the quickest way to do this. En-
large this hole gradually until you can fit your engine through
the cowl and set it on the motor mount while the cowl is
held in place with tape or by hand. Once you are satisfied
that the hole is adequate and enough clearance is left around
the engine, the edges of the cut-out can be cleaned-up and
smoothed with light sandpaper. Remove the cowl from the
fuselage.
4. Three (3) 1/2" x 1/2" x 1/2" hardwood cowl-mounting
blocks are provided. These must now be epoxied in place on
the firewall as shown on the plans. Different engine set-ups
may require that these be moved to other locations. This is
no problem, as long as they roughly represent a triangular
mounting for the cowl. It is important that these blocks be
epoxied in place at the edge of the fuselage sides at the firewall. Too far inside the edge will allow the mounting screws
to distort the cowl when they are tightened in place.
Slip the cowl over the front of the fuselage and then tempo-
rarily mount the engine with at least two screws so that it is
flat against the mount arms. Position the cowl on the fuselage so that it is properly clearing the engine and drive washer
and is square, both from the side view and the top view. Use
masking tape to hold the cowl firmly in position.
Hold the nose of the fuselage to a light source, such as a bare
light bulb and the mounting blocks can be clearly seen thru
the light yellow plastic. With a pencil, mark a hole location
directly over each mounting block, in the approximate center
of it. With a nail or other sharp object, mark and pre-punch
each of the three pencil marks on the cowl. With a 1/16" dia.
bit, drill each of the three mounting holes through the cowl
valve,
and
anything
else
that
13
and mounting blocks. Screw the three No. 2 x 1/2" cowl
mounting screws in place and remove the tape holding the
cowl to the fuselage. Slip the engine in place to be sure the
cowl is correctly in place. If tightening the cowl mounting
screws tends to force the cowl inward (distortion), that
particular mounting block should be shimmed with a scrap
piece of plywood to close the gap.
5. With the cowl removed and the engine in place, mark the
fuel line and throttle line holes. Remove the engine and drill
these holes.
6. The throttle servo can now be installed in the fuselage. The
location of this servo can vary as long as the access to it is
maintained and it's action does not interfere with the fuel
lines or the tank itself.
7. The fuel tank and fuel lines should be installed carefully to
ensure correct fuel feed. The tank itself should be surrounded
by foam rubber to keep it from "foaming" and to keep it in
place on the tank tray.
PRE-FLIGHT ADJUSTMENT AND RIGGING
Attach the wing panels and struts to the fuselage. It is NOT necessary to overtighten the wing bolts, just snug them in place.
With everything attached, stand back and view the airplane headon. If one wing appears to be low, adjust the strut clevises (both)
to correct. Once the wing panels appear the same and are square
with the stabilizer and rudder, proceed to the next step (see
diagram below).
Now turn the airplane so that you can view it from the side.
Sight down the wing panel facing you to determine if the bottom
of the wing at the tip is on the same plane as the bottom of the
wing at the fuselage. Initially, you should adjust either the forward or rear strut (they act independently) to achieve the same
plane with both the inboard and outboard wing sections (see
diagram below).
Page 15
Repeat this step on the opposite wing panel. Once you are satisfied that the wing panel are aligned properly with both the fin
and
stab
and
each
other,
"lock"
tightening the No. 2-56 nut firmly against the back of the clevises
as shown on the plans. DO NOT forget to use small lengths of
fuel tubing over each of the clevises when they are in place on your
airplane. Without these fuel line lengths in place, a clevis could,
under high loads, become "unpinned", leaving the wing without
proper support.
all
four
strut
clevises
in
place
by
BALANCING
The C.G. range (Center of Gravity) shown on the plans is the ideal
location. DO NOT exceed the rearward limit shown on the plans.
Our prototypes did not require any additional weights to achieve
correct balance. Always balance
equipment in place, ready to fly, but WITHOUT fuel.
For initial flights it is best if the airplane is slightly nose heavy.
This
condition
of stalling or snap-rolling. A slightly forward C.G. also makes the
controls somewhat less sensitive and lessens the chance of overcontrolling. As flight time and familiarity build up, you may wish
to re-balance your Cub with a more rearward C.G. to increase it's
acrobatic ability. Do this gradually and check control response
at a good altitude.
keeps
the
airplane
your
aircraft
naturally stable
"dry".
with
That
less
is:
all
chance
ENGINE AND RADIO
The engine used in your Cub should be completely broken-in
and have the ability to idle reliably. Be sure that your fuel tank
is properly installed and that the fuel lines are feeding properly.
We have found that running the tank with "manifold pressure" —
a pressure tap nipple, tapped into the muffler with the overflow
fuel line connected to it — greatly enhances fuel feed at all attitudes — the plane may go through — loops, rolls, etc.
Your radio installation should be neat with all connections absolutely secure. Do not fly without fuel line safety tubes over
clevises, as shown on the plans. Set the aileron, elevator and
rudder movements to those shown on the plans. These surface
throws
will
give
you
positive
making
it
over-sensitive.
the airplane, these throws can be changed to suit your flying
style.
control
Later, when
of
the airplane
you
are
without
more familiar
with
Your radio equipment MUST be reliable. DO NOT attempt to
fly with a radio that is suspect in any way.
FLYING
If you are a newcomer to radio control, we do not recommend
that you fly your Cub without the help of an experienced R/C
pilot.
Hobby
R/C club. These clubs can offer the beginner much assistance and
advice and they usually have a flying site that is suitable for radio
controlled aircraft.
We would suggest that for test flights, a calm day be chosen. Test
flying in strong winds can be done but it is more difficult. Although the Cub can be operated out of a relatively small area, a
sanctioned R/C flying site, with plenty of area, free of obstructions is much more desireable. Your Cub can be flown off either
asphalt or a cut-grass field. Hand launching an aircraft of this
size is not recommended.
With a full tank and the engine idling reliably, point the plane
directly into the wind, advance the throttle slowly and correct
for torque with a small amount of right rudder. The Cub should
be airborne in just a few feet. Don't let the nose come up too
sharply and use both aileron and rudder to keep the wings level
during the climb out. Climb to a comfortable altitude making all
turns gently. You will find that a medium throttle setting on the
average .40 engine is all that is required for normal flight speeds.
Make all trim adjustments at a good altitude. Use the transmitter
trim
levers
Once you are comfortable with the flying characteristics, throttle
back, while still at altitude and check stall behavior. It should be
gentle and straight without falling off on one wing or another.
Landing approach is best done under about 1/4 throttle (depending on wind conditions), keeping the wings level. As you approach
the threshold of the runway, you should be about 10 feet in the
air. At threshold, chop the throttle to full idle and settle the airplane
down
to a full stop. The Cub by it's nature, has a great deal of parasitic
drag — struts, landing gear, wheels, wires, etc. This drag can fool
you into making overly long low throttle approaches usually term-
inating short of the runway. Try to remember to use a bit more
throttle on approach and with practice spot landings of considerable accuracy can be made almost every time.
shops
in
your
to
obtain
straight and
gently on the main
area
can
direct
level
flight.
gear
and allow the
you
to
an
airplane
organized
to
roll
14
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