to view the builders construction article.

to view the builders construction article.
The Dirty Birdy is a new pattern ship by Joe Bridi whose Sun
Fly series and Kaos pattern aircraft have become almost legendary in
competition circles. All-up weight, including retracts, ranges from
7% to 8%: Ibs. and, with a wing area of 688 sq. in., this new ship
has been expressly designed for the current AMA and FAI Patterns.
Since the first flights of the prototype, the Dirty Birdy has proven
itself to be a superb pattern ship. The design makes it a gentle and rock
steady flier with absolutely no snap roll tendencies. Even though the
clean design makes a ship that moves out well in the air (from 80 to
100 mph), the landings are as slow as you'll want them to be. 2°
of down thrust is used on the engine with no right or left thrust
required. Response to the use of the control surfaces is extremely
smooth. A minimum of surface deflection is all that is necessary for it
to perform to absolute perfection. As a result, the plane is a very
predictable and reliable ship that you will really enjoy on those
Sunday morning flying sessions or at contest time.
Since most construction articles presented in model aviation
magazines are necessarily short due to space limitation in each
publication, we have asked RCM's Contributing Editor, Ben
Strasser, to present a complete step-by-step construction article with
full material list in order that vou may build the Dirty Birdy in the
shortest possible time and with as complete a set of instructions as is
possible to present. For this reason, this article is divided into two
parts. The conclusion will appear in the July 1975 issue of RIC
Modeler Magazine. In this first segment, vou can assemble the
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Ir dy
Text By Ben Strasser
materials while waiting for vour set of plans to arrive from the RCM
plans department. The canopy is available from the RCM Products
Division and, when your plans arrive, you can proceed with
Ben's instructions to cut out a complete '‘kit"’ for yourself with the
full construction of the aircraft appearing in the conclusion
of this two part series. - - - Don Dewey
If you want to get your own DB going, your first step is to put a kit
together. To save you time, we ve prepared a list of the wood and
hardware you'll need to get the job done. It's at the end of this article
so you can cut it out without messing up our glorious building notes.
Before you begin cutting the parts though, there are some other
comments we want to make. First and foremost, the hotter
the engine the better. If you fly one of the real ** go-ers””
like the new Webra, put in a 14 oz. tank if you want to fly the
whole pattern without running out of fuel. A Sullivan SS-14 fits well.
The size and shape of the canopy is critical for the superb flight char-
acteristics of the plane. If you care about that sort of thing, the cano-
pies are available trom RCM Products Division, P.O. Box 487, Sierra
Madre, California 91024. You can, of course, make your canopy
from a hollowed-out balsa block or make a plug and shape your own.
If you've done a lot of scratch-building you probably have your own
techniques for marking the wood to cut out the pieces. If this is one of
your first attempts, one way is to work with a double set of plans. Cut
up one set. Put household rubber glue onto the back of the
_ a
« .
paper pieces and glue them to the wood. Or do it the easy way and
buy a set of RCM’s adhesive backed templates for the plane
with the plans. As you read through the cutting notes that follow,
watch for the marker (57). Each one means you've read everything
about that part and you re ready to get your knife or jigsaw going.
Now, to quote a friend of ours by the name of Marvin
Barnsworthy, ‘*It’s time to get a'whittlin.
The Fuselage Parts
The top block is cut from 3/8 x 4” balsa, Cut a 3/8’ x 8’ slot in
the back end of the top block for the two rear fin sections. See plans, y
Cut the bottom block from 1/4” x 4” x 36” balsa. Because of the
thickness of the balsa, the bottom sheeting is cut in one piece. The
fuse sides are to be cut from 3/16'* x 3”* balsa. However, since the
fuse is 50” long, a 17%" length of 3/16" x 3"* balsa sheet will first
have to be joined to each of 2 pieces of 3/16" x 3" x 36” balsa. For
maximum strength, the glue joint should be cut at 45° to the grain of
the wood. See plans.wr With the 17%’ piece joined to the 36" piece,
the prepared sheet of 3/16’ balsa for the fuse sides will be 50°”
long. Cut the fuse sides from the two 3/16” x 3" x 50°" balsa sheets.
The glue joint should be located about one-third back of the front of
wing saddle. A ply doubler is added to this area later. Note that the
cut-out for the stab begins with a straight cut down to the middle of
the leading edge of the stab. The cut-out then follows the contour
of of the bottom of the stab to the rear of the fuse.
Cut the servo compartment doublers 1%’ x 13’ from 1/32” ply.*
Bulkheads | & 2 and the two fuselage wing hold-down plates are cut
from 1/4” ply.¥z Cut the notches for the motor mount rails into bulk-
head 1. Use the 3/4’ triangular stock as a guide when cutting the
top angled corners of bulkhead 1.77 Drill two holes in bulkhead 2 for
the wing dowels. ¥r Cut bulkhead 3 from 1/4’ x 4’ balsa so grain
runs from top to bottom. +7 The sub fin is cut from 3/8** x 4’ balsa.
The fuel compartment side blocks are 3/4 x 7/8" x 7” and are cut
from 3/4" x 4" x 36"" balsa plank. The back end of both side blocks
is notched out 11/16" deep by 1/4” long to allow the side block to
overlap bulkhead 2. When properly cut out, the fuel compartment
side block will overlap bulkhead 2 to be flush with the 3/16’ fuse
sides. Sand the end of the block that glues to the front of bulkhead 2
to a slight angle so the block will conform to the angle of the sides. +
The fuel compartment bottom block is 3/8" x 3%" x 7°" and is
cut from 3/8” x 4’ x 36” balsa sheet. tr The fuel compartment top
block is cut from the same balsa sheet. +7 Cut the two top block
stringers to width from the 3/8'" x 2”’ x 36"' balsa. Y
The hardwood motor mount rails are cut to shape from 1/2”* x 1%”
х 12’ beech. Note that they are cut out in the area of the fuel tank
compartment for the fuel tank. The two motor mount supports are
5/8” x 3/4 x 4” and are cut to shape from 3/4’ x 4" x 36" balsa.
From the top view they are the same shape as the front of the motor
mount rails. y The chin block is 3/4” x 344” x 4’ and is cut from
3/4" x 4" x 36” balsa. The 14” x 11%" x 236” upper
spinner ring filler block 1s cut from the piece of 2°’ x 4°’ x 6’ balsa
plank. +r Cut the spinner ring from 1/16"" plywood. ¥r The two wing
fillet base pieces are cut from 1/32” plywood using the template
provided on the plans. ¥r Finish up the fuselage portion of the kit
by cutting the various cross braces from 1/4" x 3/8” balsa.
One cross brace is located in the center of the servo compartment,
another at the location of the fuselage. Note that the cross braces
are cut to fit between the top block stringers. Yr Cut the vertical
support braces for the fuse sides from the 1/4"* x 1/4” balsa. They
are located on each fuse side behind bulkhead 3. The bottom of each
brace should be angled to mate with the 1/4”* triangular stock on
the bottom of the fuse side. Yr Also cut the bottom block cross
brace from 1/4'" x 1/4” balsa. It should be 2%4”* long. yr
Fuselage side showing wing and stab cut-outs.
Bulkheads 1, 2, and 3.
Balsa side block showing cut-out for bulkhead 2.
Fuselage top block with engine compartment top block in
Top block showing slot for fin.
Fuselage bottom view. Motor mount supports and spinner
ring filler block shown.
Fin and rudder pieces.
Stab leading edge showing notch for stab ribs.
The Fin, Rudder, Stab, And Elevator Parts
The two 3/8” x 3/4” x 12%” stab leading edge blocks are cut from
3/8’ x 4" x 36"' balsa sheet. 37 The 1/4” x 3/4” x 24” trailing edge
block is cut from 3/4” x 4’’ x 36” balsa. *7 Cut a 3/16” notch down
the length of leading and trailing edge blocks to accept the squared
ends of the ribs. See the plans. Cut the stab ribs from 1/16" x 2"
balsa sheet. The front end of the ribs are oriented toward the front of
the plane on the plans. Mark the front end of the ribs on each rib as
you cut them, otherwise you may have trouble deciding which end is
the front when it comes to gluing them in place. 4%
The stab top filler block dimensions are 3/8" x 2'" x 6-7/16"" and is
cut from the 3/8’ x 4"* x 36’ balsa sheet. The stab top
filler block is installed into the fuselage on top of the stab after
the stab 1s installed. To cut it to shape, the trailing edge of the
fuselage top block may be used as a top view template. #r
The elevator halves are cut from 3/8”* x 3" balsa. > Then, cut the
stab center rib filler block from the 2°" x 4°’ x 36"” balsa plank. 7 Cut
the 3/4” x 2°” x 7" stab tip blocks to shape from the 3/4” x 4'* x 36"
balsa sheet. The fin and rudder parts are cut from 3/8'' x 4" x 36"
balsa sheet. vr Cut out the notch for the rudder horn insert in the
proper rudder piece. vr Prepare the rudder horn insert by
laminating some pieces of 1/16" ply together. +
The Wing Parts
Cut the ribs from the 3/32” x 3” balsa. 57 If you're going to build the
wing on the RCM Wing Jig, the jig rod holes should be drilled as
indicated on the plans. Otherwise they aren't necessary. ¥r Cut the
four false ribs from the 3/16’ x 2” balsa.v The 1/2" X 3/4”
leading edge is cut from 1/2’ x 2” x 36” balsa sheet.
Cut the notched hardwood main gear supports and main gear torsion
blocks to size. Drill a 5/32” hole through the main gear support so
the hole will line up with the slot in the torsion block. See the plans. 3%
The four main gear brace pieces are to be cut from 1/16" ply; two for
each gear support. Notch out the braces for the main gear support.
When installed, the braces align with the edge of the rib, while the
main gear support aligns with the surface of the balsa center section
sheeting. vr Cut the triangular gusset tor the outboard end of each
main gear support from the 1/2" x 1/2" hardwood. ¥¢ If
you are going to use retract gear, cut the retract gear mounting plate
from 1/4" ply. > Cut the four 1/16’ ply retract gear mounting plate
braces, two for each mounting plate. vr Relieve the wing
ribs for the retract gas tubes, wires, or linkage. ¥¢
Cut the 1/4"* hardwood wing hold-down dowels to length and round
the front ends. +r The dowel support pieces are cut to 1%” x 2%”
from 1/16" ply.¥r Drill a hole in the center of each one for the 1/4”
dowel.# The wing hold-down plate is also cut from 1/16’ ply.#% Cut
the two 14°” x 2°’ x 9°" balsa wing tip blocks to shape from the 2°’ x
4 x 36” balsa plank. +7 The two center section trailing edge pieces
are 7-9/16"* long and are cut from scrap aileron stock. Notch the
center section pieces for the aileron torque rods. sx Cut the wing
fairing bottom, sides, and front piece from 1/4’ x 4’ x 36” balsa.
The bottom is 3%)” x 34”. The front is 3/4” x 34", making sure
the grain goes from side to side. The sides are 3/4" x 1%”. These
dimensions are a bit oversize to allow adequate wood so you can
sand the parts to the wing contour.w Cut the main landing
gear from a piece of 5/32" piano wire and bend
it to shape as shown on the plans. sr At this
point you should have a box full of parts and a floor full of balsa
scraps and sawdust. In reality this mess is a special, customized,
deluxe Dirty Birdy kit, all ready to build. And by now the next issue
of the R/C Modeler Magazine should be waiting for you in your mail
box with the Dirty Birdy, Part Il, to get you from the pieces to a plane.
text to page 78
from page 75/48
Before carving the top block, tack glue a
3/16" x 1/2" spacer in the aft end of the
stabilizer and fin slots. These spacers will
support the aft end of the top block during
shaping and prevent the ends from breaking
during handling.
2) Draw a centerline on the top as a guide
while shaping. Use a razor plane or knife to
slab off the corners of the top block and
sides, then start shaping the contour. Follow
the cross section on the plan for the proper
contour. Block sand until the edge of the
3/8" triangle stock is just visible. Taper the
aft top surface starting at the forward end of
the dorsal fin following the side view of the
plans. Round these corners smoothly.
Shape the aft bottom sheet corners with a
coarse sanding block since a knife will tend
to gouge out the cross-grained sheet. Carve
and sand the nose and chin area rounding the
corners to fair smoothly with the nose ring
and Former F-2B. Cover the engine intake
and exhaust parts and wrap the spinner with
a couple of layers of masking tape.
Temporarily install the engine and use the
spinner as a guide tor final shaping.
3) Mount the wing on the fuselage tem-
porarily and remove the spacers from the
slots. Insert the stabilizer into its slot and
sight from the front to check alignment with
the wing. When satisfied, epoxy stabilizer
in place, checking alignment in all planes
very carefully. Slip the fin into the fuselage
slot and seat firmly on top of stabilizer.
Trim the lower surface of the dorsal fin to fit
tightly against the top and glue to the fin.
Remove from fuselage and shape dorsal top
outline and sand contours into fin. Cut hinge
slot in aft end of fuselage and glue fin and
dorsal to fuselage and stab. Check align-
ment and be sure the fin is seated on the
stab. Temporarily mount rudder and
elevator horns and attach surfaces.
4) Check the direction of movement of
your servos and lay out and install all
pushrods. We used .062 diameter music
wire for the throttle and nosegear running in
1/8" O.D. nylon tubing. The rudder and
elevator pushrods used were Su-Pr-Line
NyRods. Cut holes through the sides and
F-3 to suit your installation. Be sure that the
rudder pushrod exits through the left side.
5) Trim canopy base to roughly fit the
fuselage. Wrap 120 sandpaper around
fuselage and sand canopy for final contour.
If you plan to add cockpit detail, make up
the parts now and fit to the fuselage contour.
A Williams Brothers 127" scale pilot is the
right size for this aircraft.
This completes the construction of your
RCM New Era Ill. Go over the airframe
again with fine sandpaper filling any dings
or cracks with Dap or Hobbypoxy Stuff and
you are ready to cover.
We suggest that you assemble the whole
aircraft and give all surfaces a final align-
ment check before starting covering. It's a
lot easier to correct any problems before
finishing the model. Check the landing gear
alignment, saddle fit, wing and tail align-
ment once again and you will be confident
of success on the first flight.
The secret of performance of this size
model is light weight. Resist the urge to pile
on a super finish with many coats of primer
and paint. In our opinion the only way to
finish your New Era III is with one of the
plastic film coverings. Properly done, this
will provide a beautiful finish with minor
weight increase. The structure is very rigid
and strong so any of the film coverings may
be used.
Cover the bottom of the wing first then
add the aileron horn links. Check aileron
operation and cover the top of the wing. If
using MonoKote, covering the tips with a
separate piece will make the job easier. The
bottom rear fuselage is covered first then a
piece of material 1s applied to each side and
wrapped around the top and seamed at the
center. Complete the fuselage covering,
then cover the tail surfaces and ailerons.
Trim to suit.
Now permanently install all control sur-
faces and control horns. Make up pushrod
ends and attach to control surfaces. Install
tank and engine mount, all gear and wheels
and connect the nosegear pushrod. Mount
engine permanently and hook up pushrod to
throttle arm. Position the radio equipment
so that the completed model balances as
shown on the plans. Install servo rails to
suit, and mount the servos. Make up the
inboard pushrod ends, check control
movement and you are ready to go flying.
Insofar as the flying characteristics of the
New Era IIl are concerned, these were
covered in the introduction to the article.
Use your normal check-out procedures for
trimming out a new pattern ship and have at
it! If you've built the New Era Ill according
to the preceeding instructions, and without
deviating from the plans, you'll find that it
will far exceed your expectations for this
size ship. In fact, we're willing to bet that its
performance, coupled with its overall
economy and ease of construction and
transportation, will have you hanging that
.60 powered pattern ship on the wall for a
Good flying. О
from page 38
that as you do, the tail will whip to one side
and you will have to correct for it. Now,
move the cyclic forward and the *‘dolly™
will take-off across the parking lot at a
surprising rate of speed. You may find that
you will be going forward and to the right or
left, while the tail is flipping to one side or
the other as you advance or retard the
throttle. At first, you'll find that it will be
difficult to accurately and precisely control
the movement of the helicopter across the
parking lot since it will want to go in several
different directions at once. Keep running
tank after tank of gas through your
helicopter until you can move it around the
asphalt training area and make it go exactly
where you want it to go! You will find that
as you utilize this helicopter *“dolly *, you
will soon be able to “drive” it around the
parking lot in any direction that you want to
— smoothly and precisely, whether 1t be
backwards or forward or to the side, and that
you can actually do Figure Eights, 360° tail
rotor turn, and the like. In other words, you
will be doing virtually all of the things that
you will be doing in the air, except that you
are safely on the ground where you will not
cause any damage to your expensive
helicopter. In fact, in the first few tanks of
fuel, you can mentally note how many times
you would have crashed your helicopter had
you been in the air instead of on the
helicopter ““dolly””. It is at this point that
you will realize the potential and ultimate
value of this training aid.
Keep working with the ‘“dolly’’ until you
can do exactly what you want to do at all
times, one tank of gas after another. When
you have a gallon or more through your
helicopter, your rate of progress will be so
rapid that it will surprise you. You, and you
alone, will be able to determine when you
are ready to actually stop using the
helicopter ““dolly”” and be ready for your
first test hops into the air. The only
difference between ““driving”” the *“dolly
on the ground and flying in the airis that you
will be using a vertical ascent mode that was
not possible with the ‘’dolly’’. Beyond that,
all movements will be the same except that
it will take less control action to move the
helicopter in the air than it did on the ground
due to the weight of the training gear and the
friction of the wheels against the asphalt or
So that's it for this month — try this
remarkable training aid and stick with it
until you are able to make your helicopter do
exactly what you want it to do all of the
time. At this point you will be ready for Part
IV of the training course and your first
initial flight with your chopper. LJ
from page 35/32
The Dirty Birdy
Materials List
Whenever we've ever done any scratch
building in the past, we've wished the
building instructions would have included a
list of the wood and such we'd need. After
having spent several hours of listing wood
sizes, checking sizes normally available at
hobby shops and so on, we now know why
they haven't done so. However, we've
spent the time for the Dirty Birdy so you
won't have to. Isn't that wonderful?
Following is a list of the materials you'll
need. Because of the special sizes of some
of the parts like the wing leading edge, and
the stab leading and trailing edge for
example, you'll have to cut them from sheet
or plank balsa. In checking the plans you'll
also find that we’ve switched wood sizes in
some cases because the wood size Joe has
cut for himself just may not be available in
most hobby shops. For example, the
fuselage top block stringers are triangular
stock with one point cut off to mate with the
fuse side. We ve used rectangular stock for
the stringers. The plans call for 5/8"
triangular stock up in the nose of the fuse.
Try to find that stuff! 3/4’" triangular stock
works just as well and is available. The
same is true of the 1/4” x 5/16” wing
trailing edge stock. We used 1/4” x 1/4”,
To find the 1/2” x 1%" x 12” beech
hardwood you'll need for the motor mount
rails, stop by a local lumber supply. Happy
Balsa Planks
lea. 2'x4 x 107 —stabcenterrib filler
block, spinner ring filler block, wing
tip blocks.
| ea. 3/4” x 4”* x 36" — stab T.E., stab
tip blocks, chin block, fuel
compartment side blocks, motor
mount supports.
| ea. 1/2’ х 2” х 36'' — wing L.E.
Balsa Strips
4ea. 3/8’ x 1/2" x 36" — wing spar.
| ea. 3/8” x 1/4” x 36" — top block cross
2ea. 1/4" x 1/4” x 36" — fuse vertical
support braces, wing T.E.
lea. 3/32” x 1/4” х 36’ — stab angle
4ea. 3/32” x 3/8” x 36°” — wing
Triangular Stock
lea. 3/4° x 36” — fuel tank
compartment, motor mount
3ea. 1/4” x 36” — motor mount rails,
rear fuse bottom, fuse wing
hold-down plates, plywood wing
fillet pieces, pieces behind bulkhead
Aileron Stock
2ea. 3/8” x 1/4 x36” —ailerons, center
section trailing edge pieces.
Balsa Sheet
lea. 3/8" x 4” x 48” — fuselage top
Zea. 3/8*?* x 4” x 36%” — fuel
compartment top block, stab L.E.,
stab top filler block, sub fin, fuel
compartment bottom, fin & rudder
| ea. 3/8” x 3” x 36’ — elevator.
lea. 3/8” x 2’’ x 36’’ — fuselage top
block stringers.
lea. 1/4 x 4” x 36 — bottom block,
bulkhead %3, wing fairing pieces.
3ea. 3/16" x 3" x 36 — fuse sides.
lea. 3/16 x2” x 36" — wing false ribs
lea. 1/16 x2" x36" — stab ribs.
6 ea. 3/32" x4" x36" — wing L.E. and
center section sheeting.
6ea. 3/32" x 3" x36" — wing ribs.
4ea. 3/32" x 2" x 36°’ — wing Т.Е.
Plywood Sheet
lea. 1/4 x 6 x 12" — bulkhead #1 &
#2, fuselage wing hold-downs.
lea. 1/16? x 6 x 12 — wing
hold-down plate, spinner ring, main
gear brace pieces, dowel support
pieces, rudder horn insert.
lea. 1/32’ x 12’ x 24” — servo
compartment doubler, wing fillet
base pieces.
2ea. 1/2” x 1%” x 12” — (beech
hardwood) motor mount rails.
lea. 1/2” x 1/2” x 12” — (hardwood)
servo mount rails, main landing gear
support gusset.
2ea. 5/8" x 1/2 x 12” — (notched
hardwood) landing gear support,
landing gear support torsion block.
lea. 1/4” x 12” — (hardwood dowel)
wing front hold-down.
| ea. nose gear steering arm
| ea. nose gear bearing
| ea. nose gear
| ea. 5/32" piano wire
| ea. Dirty Birdy canopy
6 ea. landing gear straps
| set aileron torque rods
3ea. horns
| ea. Sullivan 14 oz. slant face fuel tank
| ea. 2%’ hard rubber wheel, nose gear
2ea, 2%’ soft rubber wheel, main gear
2 ea. pushrods
3 ea. clevis and rod assembly,
nosegear steering and throttle linkage
Designed By: Joe Bridi
Competition & Sport
64% Inches
11" (Average)
688 Square Inches
Low Wing
Swept L.E.
3/8 -center with wing inverted
55% Inches
(L) 13" X (W) 3" X (H) 2%"
27% Inches
STABILIZER CHORD (incl. elev.)
7%’ Average
212 Square Inches
10" incl. sub fin
VERTICAL FIN WIDTH (incl. rudder)
9 Inches Average
‚61 су. п. (10 с.с.)
12-14 Ounces
4 (5 with retracts)
Rudder, Elevator, Throttle, Ailerons
FUSQIADO 301 tas aa ai ot Balsa and Ply
VE Ma Balsa and Ply
EMDENDADO: do ala a ee Aa: Balsa
Weight Ready-To-Fly .......... 128 oz. (dry)
Wing Loading
20.5 Ounces
(includes wing and stab area)
from page 22
There's a lot of other things you really
should have checklists for — like charging
batteries, for instance — but I just haven't
gotten around to it after all these years. And
that’s why I still qualify as a Sunday flier, |
These last two incidents led me into
recalling some of the other dumb things I've
done through the years. The list is almost
awesome, although I haven't as yet done the
one thing that nearly everybody has heard
about. I'm referring to that old, story about
the guy who was about to hand launch his
plane after making sure eveything was
working okay then proceeds to run into the
wind, with the transmitter in one hand and
the plane in the other, then throws the
transmitter into the wind and tries to control
it with the plane. Some guys swear that
really happened.
Maybe. The closest I've ever come to that
IS to launch the plane with the receiver
turned off. That's embarrassing enough, but
even more embarrassing is to launch the
plane with the receiver on, but the
transmitter off, yell **I ain't got it!” and
then have some guy standing near you say
‘Того on your transmitter, dummy!”
Believe it or not, both those things have
happened to me.
| wonder how many of you have also
done what I did once — rush to get out to the
field in the evening before 1t got too dark —
only to arrive and find that you left the wing
at home. And the reverse; fly a couple of
flights, pack up your gear and go home,
only to find that you left your plane at the
field — or your toolbox. I've done both; a
couple of years ago, at the Pioneers’ WW |
Jamboree, 1 even left my SE-5 at the field.
Considerate members held it for me — but 1
did take quite a ribbing. Deserved it, too.
One of the wildest flights 1 ever had was
when 1 was flight testing the prototype
Wavemaster. We made a lot of flights with
different height steps, to get the best
possible lift-off. To keep from having to
make a lot of hulls, we made one with a
relatively small step, then we had molded
plastic pieces which faired into the bottom
of the hull and gradually increased the
height of the step. They were held on with
waterproof tape. The idea worked great;
Dirty Birdy
O In Part 1 of this construction article we
included a list of materials you will need and
went through the process of building a
custom kit. Now it's time to get out the pins,
clamps, and glue to make something
worthwhile out of those pieces.
The building sequence begins with the
fuselage. Because of the flat top block, the
fuselage is built in typical Bridi fashion,
upside down. Next, the stab, elevator, fin,
and rudder are built. To add strength to the
symmetrical airfoil stab, angle braces are
used between the ribs. Then the wing panels
are assembled and the wing halves are
joined. Follow the construction sequence
outline and you'll get the wing dowels in so
your wing 1s properly located. Then finish
the plane, put in the equipment, and you're
ready to fly.
Since the way the plane flys is affected by
the way the wing, stab, fin, and sub fin are
installed, please follow the alignment
procedure carefully. In addition, the hinge
gaps should be kept as narrow as possible —
or seal the hinge gap with a strip of
Solarfilm. To make sure you get parts like
the wing leading and trailing edge, the stab,
the elevator, and such sanded straight, we
recommend preparing a 12 to 18 inch
sanding block. A piece of 1/2 x 2 aluminum
channel stock with sand paper glued to the
flat face works very well because it's
straight, light, and easy to handle. So the
building sequence will be easy to follow,
the first time a part is used the name is given
in italics. The marker ¥ is used to indicate
that we ve said all we're going to say about
installing a particular piece and it's time to
get out the glue.
lo get started, draw a center line down
the length of the top block, from top to
bottom on bulkheads |, 2, and 3, and down
the fuel compartment top block.¥r Draw a
line across the top block at the location of
the back of the back of the fuel compartment
top block, at the location of the cross brace
in the center of the servo compartment, at
the location of bulkhead 3, and behind
bulkhead 3 at the location of the cross
brace.% Draw a line across the fuel
compartment top block at the location of
bulkheads | and 2.57 Working on the inside
of the right and left fuselage sides, draw
lines to mark the location of bulkheads |, 2,
and 3, and the vertical support braces.
Draw a straight line on the outside of the
fuselage sides just above the wing saddle.
Each line should run from about 1'* in front
of the wing saddle to 1'' behind it and
located about 1%4' from the straight edge of
the top block. This line will be used to check
the wing incidence angle.
With the top edge of bulkhead | “up”,
mark and drill the holes for the nose gear
bearing or retract gear, and for the throttle
linkage and fuel lines. Pin the 3/8" top
block down on a flat building board with the
center line side up.“ Next, the fuel
compartment top block is to be glued in
place. If you are to use retracts, the fuel
compartment top block should be cut out to
make room for the fuel tank. Use the top
view of the motor mount rails in the fuel
compartment as a guide to mark the cut-out.
Text By Ben Strasser
You'll note that bulkhead 2 is already cut
out for this purpose. The side view of the
plans indicates the forward limit of the
cut-out. Be certain not to make the fuel tank
cut-out too far forward or else you may sand
through the top block as the nose of the
fuselage 1s shaped later. +7
After the fuel compartment top block is
glued in place, a piece of 3/8” scrap may be
used under the front end to support it while
you're working. Add the top stringers to
the top block. Note that the stringers shown
on the plans are triangular stock with one
edge of the stock cut down to make a flat
edge to mate with the fuselage side.
Because of the difficulty in preparing this
type of stringer, we have used 3/5’ x 5/8"
stock for the stringers. They should be
installed with the 5/8" side onto the top
block, butted up to the back of the fuel
compartment top block, even with the edges
of the top block, and run to the trailing edge.
The width of each top stringer will have to
be shaved in the area of the fin slot.»
Relieve the inboard corners of the stringers
in the area of the servo compartment to
make room for the servos. vr Before the glue
has set-up, add the 1/4’" x 3/8" cross brace
in the center of the servo compartment, at
the location of bulkhead 3, and behind
bulkhead 3. The cross braces should be
glued in place with the 1/4" side down. The
top block stringers may be moved in or out
slightly to insure a good glue bond to the
cross braces. vr Glue bulkheads 1, 2, and 3
in place, upside down. 77
Glue the 1/32” ply serve compartment
doubler in place on each fuselage side.*
The fuselage top block showing the stringers, cross
braces, and fuel compartment top block glued in place.
Note the top block centerline.
Add a piece of 1/4” triangular stock along
the bottom of each fuse side from the back
of bulkhead 3 to the fuse trailing edge.
Shape the 1/4" triangular stock as necessary
at the back of the fuselage sides so they can
be glued together at the trailing edge. г
Glue the 1/4” x 1/4” vertical support
brace in place on the fuse side so the angled
end mates with the 1/4 tri stock. #
When the glue has dried, glue the fuse
sides in place from bulkhead 2 to the trailing
edge. Clamp the sides to bulkhead 2,
making sure they are at 90° to the top
block. ¥r Add a piece of 1/4" tri stock along
the back of both sides of bulkhead 2. ¥¢ Glue
the bottom block cross brace 1n place
between the fuse sides. Remove any pins
from the inside of the back of the fuselage
and add the 1/4" rear fuse bottom block. vx
Glue a 9'%"* long piece of 3/4”* triangular
stock onto each side of the fuel compartment
top block so it runs from the front of
bulkhead 2 into the engine compartment. If
you've cut out the fuel compartment top
block for the fuel tank, the inside edges of
the tri stock will also have to be relieved. 7
Put glue on the side of each of the pieces
of 3/4" tri stock that is to mate with the fuse
sides. Before you clamp the fuse sides In
The fuselage sides glued in place from bulkhead #2 to the
tail, with the fuse rear bottom block added. The sides are
not yet glued in place forward of bulkhead #2.
place though, apply glue to the hardwood
motor mounts and slide the motor mount
rails in place. Next, pin and clamp the fuse
sides in place along the tri stock and to
bulkhead |. Clamp the fuse sides together in
the front so they are 2%’ across, from side
to side.
Prepare a 5/8 x 3%’ motor mount
locator template out of some scrap balsa.
This template is used to align the rear of the
motor mount rails when they are glued In
place to make sure they are level and to
build in the correct amount of down thrust
into them. ¥r Pin the template in place to the
fuse sides so it is across the front of
bulkhead 2 and rests on top of the tri stock
on each fuse side, vr Clamp the motor mount
rails in place to the fuse sides so the rear of
each rail rests on top of the template.
Remove the template and let the glue dry.
At this point the fuselage should be removed
from the building board. т
Add 1/4" triangle stock along the top and
bottom of the motor mount rails in the area
of the fuel tank compartment.¥r Shape the
sides of the upper spinner ring filler block to
fit the angle of the fuselage sides. Glue the
block in place. Cut both the top forward end
of the fuel compartment top block and upper
The bulkheads glued in place on the top block. Note that
the end of bulkhead #1 with the angle cuts is oriented
toward the fuel compartment top block.
spinner ring filler block as necessary for
your engine.vr Mark and drill the motor
mount screw holes in the rails and install the
blind nuts. When mounted, the engine
thrust washer should extend 1/8” in front of
the fuse sides.
Fit the fuel compartment side blocks by
cutting the bottom of each one to make a
straight line from bulkhead | to bulkhead 2.
Relieve the inside corner of each side block
as necessary for clearance for the wing
hold-down dowels. r Glue the side blocks
in place so they fit in the notch in bulkhead |
and overlap the side of bulkhead 2. If you're
using fixed gear, you may want to install the
tubing for your nosegear linkage at this time
because it will be more difficult to get to
after the bottom block is in place. Install
the nosegear bearing. Cut out a hole in
the front of the fuel compartment bottom
block for the nosegear strut and spring — or
relieve the center of the block as necessary
for your retract gear. Glue the bottom block
in place. 7
Mark and drill the engine mounting screw
clearance holes in the balsa motor mount
supports. Put a small piece of masking tape
on the bottom of the blind nuts in the motor
text to page 10]
Using the scrap balsa motor mount locator template
pinned in place across the front of bulkhead #2 to align
the rear of the motor mount rails.
The fuel compartment side blocks glued in place so they overlap The 1/4 ply fuselage wing hold-down plates glued in place.
the sides of bulkhead #2 and fit in the notches cut out of Pieces of 1/4 triangle stock have not yet been installed.
bulkhead #1. The rear corners of the side blocks have been
relieved for clearance of the wing hold-down dowels.
The stab ribs and cross braces glued in place to the leading and
trailing edge blocks.
The bottom of the fuselage showing the chin block and fuel tank
compartment bottom block.
NR a
The wing leading edge installed. Note the center line on rib #1
The stab is sheeted, the leading edge partially shaped, and, the
and the back of the leading edge.
tip blocks are installed.
$ с a ET - er ;
272 A5": PC o E A
A“ a. 6” Now "CS
The T.E. and top L.E. sheeting installed.
The bottom L.E. shaped to the rib contour.
The main gear support with the torsion block installed. The main gear support/torsion block assembly installed on the
bottom side of the wing. Note both the gusset at the outboard
end of the main gear support and the ply brace glued to the rib.
from page 98/69
Dale Willoughby of Model Helicopters, also
points out that they have a complete line of metric
screws, nuts, and bolts in the hard-to-find sizes
normally used on model helicopters. And, if you
are looking for floats for use with your helicopter
for water or for training purposes, Model
Helicopter has their #776 floats which are 100%
thicker overall and priced at $16.00 as well as
their standard model #775 heavy duty floats
which are 100% thicker on the bottom only, also
priced at $16.00. Both sets of floats feature
reinforced loops for the landing struts,
And that's it for this month. U)
from page 65/64
mount rails to keep out unwanted glue, and glue
the motor mount supports in place. yr Add a piece
of 3/4” tri stock down the sides of the motor
mount supports. The tri stock should be installed
so one flat side will mate with the chin block to be
glued in place next.
Relieve the top back edge of the chin block so it
will clear the bottom nosegear mounting screws
and nuts, and glue the chin block in place. Add
the two 1/4" ply fuselage wing hold-down plates
inside the fuselage. Glue 1/4” tri stock to the
bottom of the sides and back of the fuselage wing
hold-down plates?
To mount the ply spinner ring in place for a
perfect fit, use your ply spinner ring as a template
and prepare a shim out of à piece of scrap 1/16”
balsa. Tack glue the balsa shim to the back of the
aluminum spinner plate. Ÿ
Mount the engine temporarily in place. Put the
ply spinner ring onto the engine thrust washer so
it rests against the fuse. Then put the spinner plate
— with shim — in place. If the spinner plate
won t seat, sand the appropriate area of the front
of the fuse as necessary. 77 With the prop bolted in
place, hold the ply spinner ring forward to the
balsa shim on the back of the spinner plate. Don't
worry about small gaps between the spinner ring
and the fuse. Large gaps can be shimmed. Get
some epoxy between the ply spinner ring and the
tront of the fuselage and hold the ply spinner ring
up to the balsa shim while the epoxy sets up. vr
Remove the prop and engine from the fuse.
Remove the 1/16" balsa shim from the spinner
plate. 77 Use epoxy and micro balloons to fill any
gaps between the ply spinner ring and the front of
the fuselage
At this point the fuselage should be complete
except that it has not been shaped and the ply
wing fillet base pieces, fin, sub fin, and stab are
not vet installed.
Sand the inboard end of each of the leading
edge blocks as necessary so they will fit together
at the proper angle. The groove serves to center
the stab ribs and to assure a strong rib to leading
and trailing edge glue joint.» Glue the two
leading edge blocks together and pin them in
place on your building board. +r
Use the root and center ribs to space the trailing
edge block and pin it in place. *r Sand the center
rib filler block to the rib contour. Glue it and the
center and root ribs in place.*r Glue in the
remaining ribs. yr Cut and install the angle braces
using the 3/32" x 1/4" balsa stock. y
When the glue has dried and while the stab is
still pinned down on your building board, apply
the 1/16" top sheeting so it butts up to the leading
and trailing edge. Be certain that when installed,
the sheeting is seated on each rib and butts up to
the leading and trailing edge. 7 Remove the stab
from the building board after the glue has set-up
and install the bottom sheeting. Yr Cut the leading
edge to shape and finish sand it with your 12-18
inch sanding block. See the plans. *7 To shape the
trailing edge, tack glue the elevators to the stab
T.E., then sand the stab T.E. down to size. ¥r Add
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the stab rip blocks and sand them to a sharp edge
as shown on the plans. 7
Break the tack-glued elevaror halves free from
the stab and sand them to shape. The T.E. of the
elevators should be left 1/8" thick rather than
sanded to a sharp edge. Do not install the
elevators onto the stab yet. They are to be hinged
after the stab is installed on the fuselage. +
Glue the two rear fin pieces together. The
forward fin piece should not be glued in place
until after the other fin pieces are glued to the
fuselage. Glue the rudder pieces together and
add the plywood rudder horn insert. 1f you want
to make the rudder horn insert flush with the
surface of the rudder, you can either laminate
several pieces of ply together or add a piece of
scrap balsa to one side. vr Sand the sides of the fin
and rudder smooth. +7 Round the fin tip and taper
the rudder T.E. down to 1/8". Do not hinge the
rudder until the fin has been installed onto the
fuse. yr
At this point you should have the stab,
elevators, a forward fin piece, the fin, and the
rudder ready to install,
Lay both pieces of leading edge stock on your
workbench with the 3/4” side down. Draw a
center line down the length of the top side. Also
draw a center line down ribs 1, 6, and 11, from
the leading to the trailing edge. 77 Finally, relieve
the appropriate ribs for your landing gear. If
you re using fixed gear, the bottom of ribs 3 and 4
should be notched for the hardwood main gear
support. The support should be mounted so it will
be just flush with the balsa center section
sheeting. If you're using retract gear, the ribs
should be relieved for the 1/4" plywood retract
gear mounting plate just deep enough so the
mounting flange on the retract gear is flush with
the balsa center section sheeting. Also relieve the
ribs for the retract gas tubes, wires, or linkage. v¢
When you build the wing panels, rib | is to be
glued only to the leading and trailing edge pieces.
It should not be glued to the spars and leading and
trailing edge sheeting. That will allow you to
adjust the angle of the root rib on each panel so
they will mate squarely when the wing panels are
joined. With the angle of the root rib properly
adjusted, each one is glued to the spars and
sheeting. Then the wing panels are joined.
Building The Wing Panels
On A RCM Wing Jig
To build the wing panels on a wing jig, use the
sequence outlined for building one wing on a
building board which follows. However, to make
sure the ribs are properly spaced, mark the
location of the ribs on the spars and trailing edge
stock. Begin by putting the ribs onto the jig, then
pin and glue the bottom spar in place.
Building The Wing Panels
On A Building Board
Before you get started, save yourself some
grief by checking out your building board with a
straight edge or carpenter's level to make sure
you have a flat surface. To make the work easier,
set up your wing so the leading edge is toward the
front of your workbench.
Since the wing is built top side up, begin by
pinning the 3/8’ x 1/2” bottom spar down.
Pin rib | in place on the spar but do not glue it. Я;
Pin and glue the other ribs in place on the bottom
spar. The ribs relieved for the landing gear should
have the notched side down. Add the trailing
edge, making sure that the ribs are at 90° to the
trailing edge stock. Note that 5/16" x 1/4" stock
is called for on the plans, but 1/4" x 1/4” is more
readily available and works just as well. ¥ Sand
the trailing edge to the rib contour with the king
sized sanding block. Add the 3/32’ x 2’ top
trailing edge sheeting, but don't glue it to rib 1.7
Block up the trailing edge of the wing as
necessary so the center lines on ribs I, 6, and | |
are parallel to your building board. Glue the top
spar in place to ribs 2-11 and pin it to rib 1.77 Add
the leading edge so the center line aligns with the
center line on ribs 1, 6, and | |. Center the other
ribs on the leading edge. vr
Use your X-Acto knife to roughly shape the top
of the leading edge stock to the rib contour. Then
sand it smooth to the rib contour with the big
to page 105
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from page 102/64
sanding block. The front of the leading edge
should not be rounded until the top and bottom
sheeting have been installed. Add the
3/32" x 4" leading edge sheeting so it goes to
the center of the spar and overlaps the leading
edge. Do not glue the leading edge sheeting to rib
|. The outside of the sheeting may be dampened
with a sponge so it will bend to the rib contour
easily. ¥r Trim the leading edge sheet flush with
the front of the leading edge.” Add the
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3/32" x 4” center section sheeting pieces, but
don’t glue themtorib |.% Glue the 3/32" x 3/8"
capstrips in place.
Remove the wing from the building board.
Shape the bottom of the leading and trailing edge
to the rib contour. vr Add the bottom trailing edge
sheeting. vt
Build the second wing panel in the same way.
Be sure to set up the other wing panel carefully so
you won't end up with two right or left wings.
Now it's time to glue rib | of both wing panels
in place. To find the proper angle, turn the wing
panels upside down and move them together.
With the spar at the tip rib down on the building
board, block the center of each wing panel up 3/8
of an inch. Adjust the angle of rib | on each wing
panel so these ribs will mate squarely when the
wing panels are joined. Glue rib | on each wing
panel in place to the spars and the sheeting.
Trim the leading edge, spars, trailing edge, etc.,
flush with rib 1.47 Glue the wing panels together
using 5 minute epoxy. As you do so the center
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won't get inside, and glue the center section
trailing edge pieces in place. Add the 1/16” ply
hold-down plate on the bottom of the wing with 5
minute epoxy. See the plans. 7
As preparation for the installation of the wing
hold down dowels, draw a line on the bottom
back of bulkhead 2 to indicate the location of the
center of the wing dowel holes.
Time to align the wing to the fuselage. Lay the
fuse upside down on your workbench and tape the
back end down so it won't move. Put the wing in
place in the wing saddle. Center the wing on the
fuselage by measuring the distance from each tip
rb to the fuselage side. To assure the wing is
straight, measure the distance from each wing tip
to a point on the center of the trailing edge of the
fuselage. Obviously, both distances must be the
same. Mark the location of the fuselage on the
leading and trailing edge of the wing. Also draw a
line down the wing cord on the fuselage side of
the wing along both sides of the fuselage — to
mark the location of the outside of the fuselage
sides. This line will be used to locate the ply wing
fillet base pieces. Also mark the location of the
holes to be drilled in the wing for the rear
hold-down bolts. Drill a pilot hole through the
wing hold-down plate into the 1/4" ply plates in
the fuselage to mark the location of the holes. Y:
Remove the wing from the fuse. If the holes are
properly located on the fuselage hold-down
plates, drill out the clearance holes in the wing for
the 6/32 hold-down screws. Also drill the holes in
the plates for the blind nuts and install the blind
nuts on the bottom side of the fuselage wing
hold-down plates. y7
Next the alignment of the wing saddle is to be
checked, First the wing fillet base pieces should
be taped in place on the wing. Working on the
wing, draw a line down the wing cord 3/16"
inboard of each of the lines you drew earlier,
Tape each //32"" wing fillet base piece to the wing
SO 1t butts up to this inboard line. Be certain that
the tape will be clear of the wing saddle. Put the
wing in place on the fuselage to check the
alignment of the fillet base pieces. ¥r If they are
okay, run a strip of masking tape down the wing
SO it butts up to the straight-edge of the ply fillet
base pieces to prevent glue from seeping out from
the saddle and gluing the wing in place. Now
you re ready to get to the final alignment of the
saddle. gr
With the fuselage still taped down on your
workbench, bolt the wing in place. To assure the
wing 1s level, measure the distance from each
wing tip to the workbench. To check the wing
incidence, work on one side of the wing at the
fuselage. Measure the distance from the center of
the leading edge to the line you drew earlier on the
fuse side. Also measure the distance from the
center of the trailing edge to the other end of the
same line. Because the wing incidence is slightly
positive, the distance should be 1/32’ more at the
trailing edge. Double check yourself by
repeating this process on the other side of the
fuse. 77 Remove the wing and sand or shim the
saddle as necessary to assure that the wing is level
to page 110
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actual size :1x1.5x.6 GUARANTEE
le An Automatic Recycling timer that gives mid-flight signals as
well as end of flight warning. You pace yourself.
e À Safety Monitor which sounds its alarm when your
transmitter is left or accidently turned on
IC Reliability e 70db Audio Output e instant Set/Reset e Pre-
select 2-10 min ¢ Custom Molded Case e 9-12V Transmitter
powered at 7ma drain e 2 hour assembly time e Guaranteed
Success — Direct Mail Only — Send Check or Money Order.
Overseas Air Mail Add $1.50 Wa State Res Add Tax.
P.7. Box 495
“Make any water a flying site."
DELUXE KIT — $29.50
Includes ALL balsa sheeting,
hardware, wire, glass cloth.
BASIC KIT — $14.95
Cores, keels, blocks only.
Box 11-A, Mountlake Terrace, WA 98043 J
So you can take advantage of this
unheard of low price. Mattell, Inc. offers
you this price on a limited quantity of its
Signal Command® R/C equipment.
Each unit has been individually tested and
pre-wired and is guaranteed against
factory defects for 30 days.
Units are available functioning on any one
of the five 27 MHz Bands.
Airborn command range of up to one mile.
Operates on 9 volts — 6 C-Cell batteries. *
Battery monitor light.
Stick control plus trim control.
Hi-impact plastic case with convenient
side handle.
Lightweight — less than 3 ounces.
Operates on two pen-cell or NiCad
batteries — 2.4 to 3 volts. *
Magnetic actuator.
* Batteries not included.
TO ORDER your Mattel Signal Command
Single Channel Pulse Radio Control Unit,
simply complete the coupon below and send
with your check or money order (sorry no COD
orders) to: Mattel, Inc., M.S. 504CS, 5150
Rosecrans Ave. Hawthorne, California 90250.
“1973 Mattel Inc.
Radio Control Unit MS 504CS
Mattel, Inc.
5150 Rosecrans Avenue
Hawthorne, California 90250
Please send me Signal Command Radio
Control Units. Frequency desired . | have
enclosed $29.95 for each unit ordered (plus 6% tax
for Calif. residents). (Sorry no COD orders) Postage
Address . ls = — SEES
City _
State_ Zip E
Your complete R/C Center is Fitts Photo and
Hobby Shop, Kings Hyway Plaza - Route 108
Stratham, N.H. (603) 778-8802. Open weekdays
10-9; Sundays 1-6. Kraft — MRC — EK — Enya
— US Max — Fox — Kits and accessories
We fly ourselves.
(27072) PRODUCTS
over 150 specialized items for:
send 25¢< for illustrated catalog
When writing to RCM,
Be sure to include your zip code!
from page 106/64
and is at the proper incidence. Put the wing back
in place and check it again. Don't worry about
trying to get an exact wing-to-saddle fit since the
ply fillet base will give you a perfect fit when
you re done. 77
When the saddle is okay, put a thin coat of 5
minute epoxy on it. Bolt the wing in place and
push down firmly on the front center of the wing
to assure the forward end of the fillet base pieces
will seat properly to the wing saddle. Yr While the
wing is still in place on the fuselage, use the
marks on the back of bulkhead 2 to mark the
location of the holes for the wing hold-down
dowels on the wing leading edge.¥r After the
epoxy on the fillet base pieces has set-up, remove
the tape from them and remove the wing from the
fuse. The fuselage may be removed from the
workbench. vr
Any gaps between the wing fillet base pieces
and the saddle may be filled with epoxy. ¥r Add
pieces of //4'' triangular stock to the fillet base
pieces along the fuselage sides. Use 5 minute
epoxy to glue the back ends of the fillet base
pieces to the fuse sides.% Add //4” triangle
stock to this area as well, +
Drill the two 1/4" holes through the leading
edge for the hold-down dowels.¥r Now you're
ready to glue the dowels in place. Bolt the wing in
place onto the fuse. Put the ply dowel support
pieces onto the wing hold-down dowels. Slide one
end of the dowels through the holes in the wing
leading edge and into the holes in bulkhead 2.
Add some 5 minute epoxy to the back of the ply
dowel support pieces and, while holding the wing
firmly in the wing saddle, slide the dowel support
pieces to the rear so they'll glue to the front of the
top and bottom spar. vr Glue the dowels to the ply
support pieces and to the wing leading edge. 7
Add a false rib to both sides of each dowel. 2;
Remove the wing from the fuselage. Ÿ
Glue the bottom leading edge sheeting in place
as you did the top leading edge, and trim it flush
with the leading edge. If you are using fixed
gear, glue the torsion block to the bottom side of
the main gear support. The grooved side of the
torsion block should be oriented toward the
outboard end of the main gear support. + Glue
one 1/16” ply main gear brace on the inboard
side of rib 3 and the other on the outboard side of
rib 4.Y7 Glue the main gear support/torsion block
assembly in place so the torsion block is glued to
the main gear brace on rib 3.¥r Add the triangular
hardwood gusset at the outboard end of each main
gear support. (If you're using retract gear, glue
the retract gear mounting plate in place. vr Add
the 1/16” ply retract gear mounting plate
braces.) t
Add the bottom center section sheeting and
capstrips.¥r Use your King sized sanding block to
round the leading edge. For the desired flight
characteristics the leading edge should be blunt
rather than sharp. See the plans. Trim the
leading edge, top and bottom sheeting and the
trailing edge sheeting flush with the tip rib. % Add
the rip blocks and sand them to a sharp edge along
the tip as shown. +7
Use 4 to 6 oz. glass cloth at least 5 inches wide
with resin to reinforce the wing center section. vr
Sand the ailerons to shape. A slightly rounded
1.E. about 1/8” is recommended. xr Install the
ailerons using at least 4 hinges for each one. The
outboard hinge should be within 1/2"* of the end
of each aileron. xr
Put the wing in place on the fuse and glue the
wing fairing front, sides, and bottom in place
using 5 minute epoxy. vr Holding the wing upside
down at the center section, do a tip to tip balance.
Add weight to either wing tip as necessary. yr
The aileron servo well may now be cut into the
top side of the wing.yx Add the 1/2” x 1/2”
hardwood servo mounting rails into the servo
cavity. vv
Time to check the stab saddle and mark the stab
for installation. With the fuse upside down on
to page 112
Sailing Yachts For
Radio Control
LENGTH 136 in
BEAM 94 in
SAIL AREA 600 so in
LENGTH 50 in
BEAM 11% in
SAIL AREA 800 sq in
Complete kits include molded plastic
hull and components, all rigging, finished
sails and semi-finished wooden parts.
$ 74.95
11715 Adenmoor Ave. Downey, Ca. 90241
Calif residents add 6% tax DEALERS WELCOME
9" J-3 CUB
e 106” WING SPAN
PHONE (404) 355-2975
from page 110/64
your workbench, mount the wing in place. Put the
stab in place to check the alignment. The L.E. of
the stab cut-out in the fuse may have to be
enlarged a little to get the stab in place. +r Make
sure that (1) the distance from the stab tip to the
fuse is the same, for both stab sides, (2) the
distance from the center of the stab L.E. and T.E,
to the workbench is the same for each stab panel
(0° incidence) and for both panels, and, (3) the
distance from the L.E. of one stab tip to the T.E.
of the wing tip rib on the same side of the fuse is
the same as for the other stab panel. Mark the
location of the fuselage on the leading and trailing
edge of the stab so you will be able to locate it
properly when you are ready to glue it in place.
Sand or shim the stab saddle as necessary. vr
Turn the fuse right-side-up and glue the fin rear
sections piece in place. The fin T.E. should be
aligned with the fuse T.E. and it should be at 90°
to the fuse top. Eyeball the fin from the front in
relation to the wing to make sure it's okay before
the glue sets up.¥r Add the forward fin piece. +
To glue the sub fin in place, first pin the rudder to
the fin. Then use the rudder to align the T.E. of
the sub fin. The L.E. of the sub fin should be
centered on the fuse bottom. 7
Remove the wing from the fuse. File and sand
the fuselage and wing fairing to shape. Use 3/4
oz. glass cloth and resin on the fuselage, stab, fin,
sub fin, rudder, wing fairing, and elevator.¥r
Shape the bottom of the balsa stab top filler block
so it fits to the top half of the stab. vr Glue the stab
in place in the fuselage using 5 minute epoxy,
making sure it's properly aligned. Epoxy must be
used for this joint because the stab has already
been covered with resin and glass. ¥ Add the stab
filler block by sliding it in place on top of the stab.
It should be glued to the top of the stab and the
fuselage. ¥r Hinge the rudder using at least three
hinges. By making aslight * V”* notch inthe T.E.
of the fin and cutting the L.E. of the rudder to a
slight *“*V” shape, the hinge gap may be
minimized. The bottom hinge should be into the
sub fin. 7
Install the elevator horns onto each elevator
half. Each one should be cocked forward at 15”.
This will assure that both inside and outside loops
take the same amount of control on the elevator
stick. Using a horn on each elevator half means
that the elevators are independently adjustable; a
feature important for fine trimming of the
airplane. For additional strength, a piece of 1/16"
ply may be countersunk into the elevator halves at
the 15° angle in the location of the elevator
horns. ¥r Prepare the stab T.E. and elevator L.E.
as you did the fin and rudder.¥r Install at least
three hinges on each elevator half. x
Finish the area under the canopy as it will be for
the finished airplane and install the canopy using
Hot Stuff. Use resin and micro balloons to build
à fillet around the canopy, along the sides of the
bottom wing fairing, along the stab/fuse joints
For additional information, brochure and catalogue send 0.50¢
P.O. BOX 9641
SAN DIEGO, CA. 92109
and along the fin and sub fin/fuse joints.
Complete the wing fillet by adding resin and
micro balloons to the plywood plate to get the
desired shape. See the plans. yr
Cut the pushrod exit holes for the elevator and
rudder. See the plans. Note that the rudder
pushrod exit hole is actually on the bottom of the
fuselage, near the sub fin. *
The rudder and elevator pushrods may be
prepared at this time. Since the split elevator will
need two rods and clevises at the rear, double
clevis rods will have to be attached to the rear of
the elevator pushrod. 37
Install the nosegear steering linkage. The
steering arm should be at an angle to bulkhead |
so it will be free to move back and forth. 5% Install
the main landing gear. If retracts are used, the
main gear struts should be cut so the plane rests on
the ground with a slightly positive incidence. The
wheel wells may be cut out. Add hardwood rails
above the retracted nose gear to support the fuel
To set up the CG, the plane should be finished.
The landing gear, engine, muffler, fuel tank,
battery, and receiver should be installed. The
pushrods should be in place inside the fuse. Lay
the servos on top of the fuselage and move them
fore and aft until the desired balance point is
found. Then the servos are mounted inside the
fuselage at this location.
While the specific location of the CG in a
pattern ship is a matter of personal preference, we
recommend locating it at a point approximately
6%" in front of the T.E. at the wing tips for your
first flights. Above all, the plane must not be tail
heavy. The CG may then be checked in flight by
putting the plane into a tightly banked turn. If the
nose drops, the plane is nose heavy. If the tail
drops during the bank, the plane is tail heavy.
Shift the battery pack or add weight to the nose as
necessary. The CG may also be checked by
putting the plane into a spin. If it wants to go into
a spiral dive instead, it's nose heavy. The landing
is another thing to check. If elevator must be
added to keep the plane flared out for the touch
down, it may be nose heavy.
With the plane standing on the ground,
measure the distance of each wing tip to the
ground. Bend the main gear as necessary so the
wing tips are level. Eyeball the plane from the
side. It should rest in a slightly nose-up
Check the roll of the plane to make sure it rolls
straight.Ÿ» Check the operation of the control
surfaces to make sure they operate freely and in
the direction they should.% With someone
holding the plane, check the operation of the
surfaces with the engine running wide open — to
check for the effects of vibration.*7 And do a
distance check with your radio.
Time to go a'flyin”. О
from page 51/50
model got up to flying speed, but if you leaned it
out enough to prevent this, the engine would
starve before you could get it moving forward.
Then, you could hold the plane nose up (the tank
is in front of the engine) and get it a bit rich, then
let go and hope, but that was unreliable. So what
to do?
This is what 1 do. It works for me, with the
engine | have. I use a very small diameter fuel
line. In order to draw through the line, the needle
valve setting has to be open a bit more, but once
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