Composite-ARF Extra 260 User manual

Composite-ARF Extra 260 (2.6m span)
Instruction Manual
Composite-ARF Extra 260, 2.6 m
TAVS Technology Version 1.0

Instructions for Extra 260 IMAC-Airplane
Thank you very much for purchasing our Composite-ARF Extra 260 all composite aircraft, made
with the revolutionary Total Area Vacuum Sandwich (TAVS) technology. It is based on our 3m
version of the Extra 260, but reduced in size to suit the most popular 75 - 120cc engine sizes.
A few of the photos in this instructions that explain ‘standard’ techniques and methods are actu-
ally of parts from different planes, and this will be obvious from the paint colors/schemes - so
please don’t get confused !
Before you get started building and setting-up your aircraft, please make sure you have read
this instruction manual several times, and understood it. If you have any questions, please
don’t hesitate to contact us. Below are the contact details:
Email: [email protected]
Telephone: Phone your C-ARF Rep!!! He will be there for you.
Website: http://www.composite-arf.com
Liability Exclusion and Damages
You have acquired a kit, which can be assembled into a fully working R/C model when fitted out
with suitable accessories, as described in the instruction manual with the kit.
However, as manufacturers, we at Composite-ARF are not in a position to influence the way you
build and operate your model, and we have no control over the methods you use to install,
operate and maintain the radio control system components. For this reason we are obliged to
deny all liability for loss, damage or costs which are incurred due to the incompetent or incorrect
application and operation of our products, or which are connected with such operation in any
way. Unless otherwise prescribed by binding law, the obligation of the Composite-ARF compa-
ny to pay compensation is excluded, regardless of the legal argument employed.
This applies to personal injury, death, damage to buildings, loss of turnover and business,
interruption of business or other direct and indirect consequent damages. In all circumstances
our total liability is limited to the amount which you actually paid for this model.
BY OPERATING THIS MODEL YOU ASSUME FULL RESPONSIBILITY FOR YOUR ACTIONS.
It is important to understand that Composite-ARF Co., Ltd, is unable to monitor whether you
follow the instructions contained in this instruction manual regarding the construction, operation
and maintenance of the aircraft, nor whether you install and use the radio control system
correctly. For this reason we at Composite-ARF are unable to guarantee or provide a
contractual agreement with any individual or company that the model you have made will
function correctly and safely. You, as operator of the model, must rely upon your own expertise
and judgement in acquiring and operating this model.
Supplementary Safety Notes
Pre-flight checking:
Before every flying session check that all the model’s working systems function correctly, and be
sure to carry out a range check.
2

The first time you fly any new model aircraft we strongly recommend that you enlist the help of
an experienced modeller to help you check the model and offer advice while you are flying. He
should be capable of detecting potential weak points and errors.
Be certain to keep to the recommended CG position and control surface travels. If adjustments
are required, carry them out before operating the model.
Be aware of any instructions and warnings of other manufacturers, whose product(s) you use to
fly this particular aircraft, especially engines and radio equipment.
Please don’t ignore our warnings, or those provided by other manufacturers. They refer to things
and processes which, if ignored, could result in permanent damage or fatal injury.
Attention !
This IMAC-Aircraft is a high-end product and can create an enormous risk for both pilot and
spectators, if not handled with care, and used according to the instructions. Make sure that you
operate your Extra according to the AMA rules, or those laws and regulations governing the
model flying in the country of use.
The engine, servos and control surfaces have to be attached properly. Please use only the
recommended engines, servos, propellers, and accessories supplied in the kit.
Make sure that the ‘Centre of Gravity’ is locat-
ed in the recommended place. Use the nose
heavy end of the CG range for your first flights,
before you start moving the CG back to a more
critical position for 3D-maneouvers. If you find
that you need to relocate your batteries or even
add weight in the aircraft to move the CG to the
recommended position, please do so and don’t
try to save weight or hassle. A tail heavy plane,
in a first flight, can be an enormous danger for
you and all spectators. Fix any weights, and
heavy items like batteries, very securely to the
plane.
Make sure that the plane is secured properly when you start the engine. Have at least 2 helpers
hold your plane from the tail end, or from behind the wing tips, before you start the engine. Make
sure that all spectators are behind, or far in front, of the aircraft when running up the engine.
Make sure that you range check your R/C system thoroughly before the first flight. It is absolute-
ly necessary to range check your complete R/C installation first WITHOUT the engine running.
Leave the transmitter antenna retracted, and check the distance you can walk before ‘fail-safe’
occurs. Then start up the engine, run it at about half throttle and repeat this range check with the
engine running. Make sure that there is no range reduction before ‘fail-safe’ occurs. Only then
make the 1st flight. If you feel that the range with engine running is less then with the engine off,
please contact the radio supplier and the engine manufacturer and DON’T FLY at that time.
Check for vibrations through the whole throttle range. The engine should run smoothly with no
unusual vibration. If you think that there are any excessive vibrations at any engine rpm’s, DON’T
FLY at this time and check your engine, spinner and propeller for proper balancing. The light-
3
NO !!!
Secure the plane
before starting the engine.
DANGER ZONES
NO NO

4
weight sandwich composite parts don’t like too much vibration and they can suffer damage. The
low mass of all the parts results in a low physical inertia, so that any excess vibrations can affect
the servos and linkages.
Make sure that your main and stab tubes are not damaged. Check that the front and rear anti-
rotation pins for the wings and horizontal stabiliser are located correctly in their holes, and are
not loose. Check that the 4 plastic wing retaining nuts are tight, that the M3 bolts retaining the
horizontal stablisers on to the aluminium tube are installed and tight, and that the hinge wires for
the rudder and elevators cannot come out.
If you carefully checked all the points above and followed our advice exactly, you will have a safe
and successful first flight - and many hours of pleasure with your Composite-ARF Extra 260.
General information about
fully-composite aircraft structure and design
All the parts are produced in negative molds, manufactured using vacuum-bagged sandwich
construction technology. All parts are painted in the moulds, either single colour or designer
colour schemes. A new production method, called TAVS (Total Area Vacuum Sandwich), enables
us to present this aircraft with incredible built-in strength, while still being lightweight, and for a
price that nobody could even consider some years ago. This production process has huge
advantages, but a few disadvantages as well. These facts need to be explained in advance for
your better understanding.
Description of Parts
The Wings:
Both wing halves are made in negative moulds, fully vacuum-bagged, using only 2 layers of cloth
in combination with a hard 2mm foam sandwich to form a hard and durable outer skin. Because
of this TAVS technology no additional structural parts are needed except for the main spar tube.
The ailerons are already hinged for you. They are laminated in the wing mould and are attached
to the main wing with a special nylon hinge-cloth, sandwiched between the outer skin and the
foam. This nylon hinge is 100% safe and durable. You never have to worry about breaking it, or
wearing it out. There is no gap at all on the top wing surface, and there is a very narrow slot in
the bottom surface, where the aileron slides under the main wing skin during down throw. This
hinge setup is the cleanest you can ever obtain, but you have to take some care during assem-
bly for proper installation and servo set up.
First, the hinge line is on the top surface of the wing, not in the centre. This is NOT a disadvan-
tage, if you set in about 10% NEGATIVE aileron differential in your transmitter program. This
means that the ‘down’ throw needs to be about 10% more than the up throw.
Why? Because the axis of the hinge is not at the centreline of the aileron, so it moves slightly
in and out when it travels, and the aileron gets a little "bigger" in surface area when moving up,
and "smaller" when moving down. This is why you have to set the negative differential in your
transmitter to compensate for the size changing. 10% is a good starting point, and you will find
out the exact setting during the first flights, doing fast vertical rolls and watching the fuselage
rolling in a perfect line. You can set it perfectly, this is guaranteed.

The bottom slot needs some explanation, too. The cut line
is exactly in the correct position so that the aileron slides
under the wing skin smoothly. If the cut was a few mm for-
ward or back, it would not work properly. So, make sure that
the lip is not damaged, and that the aileron slides under this
lip perfectly. It will NOT lock at any time, as long as the lip
is not damaged. If damage occurs to the lip, you can cut off
2-3 mm, but you should NEVER need to cut off more than
this.
Make sure that the control horns are glued into the ailerons properly. The hole in the phenolic
horn for the quick-link needs to be exactly perpendicular to the hinge axis line, and in this man-
ual we show you a simple way to ensure that the horns in all pairs of control surfaces will be iden-
tical, making it easy to set up your R/C for accurate flying manoeuvres.
The wings are already set-up with servo covers and hatches for 2 servos per aileron, and we rec-
ommend a pair of high-torque servos, for example the JR DS8411, in each wing. Our servo cov-
ers and milled plywood mounts make installation, and exchange if necessary, very quick and
easy and provide a rock solid servo mounting and linkage system.
The wings are attached to the fuselage with the 4 threaded
aluminium dowel anti-rotation pins, with 4 plastic nuts
inside the fuselage. If the aluminium dowels come loose in
the wing, the wing will slide outwards, away from the fuse-
lage, and the main spar tube will definitely break. So take
great care to inspect the glue joints of these anti-rotation
dowels in the wing REGULARLY. Excessive vibrations or
hard shocks can cause the glue joints to weaken or break.
Monitor these joints whenever you set up your plane. Never
forget to tighten the nuts inside the fuselage. Please DO
NOT modify these attachment dowels in any way, their per-
fect function is proven for many years.
The Fuselage:
The fuselage is also made in negative moulds, and is all
constructed using TAVS technology. All the loadbearing
internal parts are installed during manufacture, to ensure
accurate location and reduce your assembly time. The
fibreglass tubes in the wings to receive the wing spar tube,
the stab spar tubes, and the holes and reinforcement plates
for the anti-rotation dowels, are already installed. There is
no need to even check the incidences - you can be assured
that these are already set in the moulds so that no adjustment is necessary.
The landing gear mount is strong and doesn’t need any extra reinforcement. The fuselage is
extremely light weight, and the gear loads need to be led into the structure gently. No glue joint
needs to be stronger than the materials that it is attached to, as it would just result in increased
weight for no advantage. The landing gear is a fairly flexible design, which works very much like
shock absorbers. This plane is not made for crashing, but the landing gear will take some hard
landings without problems. Do not change or modify it, as the results would only be negative. We
had plenty of time and experience to engineer the strength needed in this area - and we did !
The motordome and firewall are a fully integral parts of the fuselage, and provide plenty of
5
Centreline of hinge axis
Phenolic control horn

strength for any engines up to 120cc on the market today.
See the Engine Installation section for details of engine and
setting thrust angles.
The engine cowling should be attached using the method
shown. It is only a little work and this mounting has been
tested and proven for many years.
The Stabilisers:
The stab parts are also vacuum bagged sandwiched. The
rudder and the elevator control surfaces are hinged with
4mmØ tubes, fitted through phenolic hinge bearing plates
which are jig-installed during manufacture for perfect align-
ment.
The rudder and elevator design allows for at least 50
degrees throw. For the Extra it is mandatory that the tail
area is extraordinarily light weight, so the stab is designed
for one powerful servo installed in each half. All the struc-
tural parts are preinstalled. The horizontal stabs are mount-
ed with one 20mm aluminum tube and one 10mm carbon
anti-rotation pin each.
Servo Screws:
Fix the all the servos into the milled plywood servo mounts
using the 2.9 Ø x13mm sheet metal screws provided in the
kit, not the standard screws normally supplied with servos
by the servo manufacturer. This is because all the holes in
our milled servo mounts are 2mm diameter, due to our CNC
manufacturing process, and this is too big for the normal
screws.
Take Care:
Composite sandwich parts are extremely strong, but fragile
at the same time. Always keep in mind that these contest
airplanes are designed for minimum weight and maximum
strength in flight. Please take care of it, especially when it
is being transported, to make sure that none of the critical
parts and linkages are damaged. Always handle your air-
plane with great care, especially on the ground and during
transport, so you will have many hours of pleasure with it.
6
(above) The lightweight fin-post
has the phenolic rudder hinge
posts already installed and aligned
at the factory. The corresponding
tubes are also installed in the rud-
der for the hinge tube.
(below) The elevator and rudder
hinging uses 4mm diameter alu-
minum tubes, inside phenolic
hinge posts that are factory-
installed and aligned.

Accessories
Below are the things you may need to get your Composite-ARF Extra 260 (2.6m) in the air. Some
of them are mandatory, some of them can be chosen by you. What we list here are highly rec-
ommended parts, and have been thoroughly tested.
1. Power servos (min. 8 required). We highly recommend JR 8411 or 8511/8611 for all con
trol surfaces. For Futaba users, we recommend 2 x S9351’s for each Aileron, 1 x S9351
for each elevator, and 2 x S3951’s for rudder.
2. Aluminium servo output discs, or full metal arms (8 pieces). We strongly recommend that
you attach the phenolic servo extension arms provided in the kit to metal servo output
discs, or use full metal servo arms (eg: SWB ‘Double-Loc’ type). The rudder phenolic servo
horns must be attached to metal servo output discs (eg:‘Hangar 9’ #HAN3526 or 3520).
3. Throttle servo. Any standard servo will do (eg: JR/Graupner 4041/5391)
4. Aluminum Spinner 115 - 125 mm/4.5 - 5” dia. eg: Tru-Turn. (Ø120mm carbon spinner
& CNC T6 alu. backplate available from C-ARF as an option, #810100 - 810105+)
5. Main wheels 115 - 125 mm (4.5 - 5"). Kavan Light or Dubro wheels are recommended.
6. Engine 75 - 100cc. The DA-100 is probably the most commonly used engine for our 2.6m
span Extras, and the mounting dimensions are shown for this motor. However in these
instructions we also show the installation of a lightweight option with a 3W 80cc single
cylinder and tuned pipe set-up.
7. Muffler/Canister or Tuned pipe(s) and headers. (Headers, canisters, tuned pipes and
Teflon joiners are available from C-ARF as options. See our webpage for availability)
8. Tailwheel assembly. (Available as an option from C-ARF. Product # 801000.)
9. High quality heavy-duty servo extension cables, with gold connectors. High quality
receiver and ignition switches, etc.
10. Receiver and Ignition batteries.
11. Powerbox and dual powerswitches for dual batteries (available from C-ARF as an option)
12. Fuel tank (750 - 900 ml) with gasoline stopper. We used a Dubro #690 in this plane.
13. Cable ties in various lengths.
14. Propeller. Carbon Meijzlik or Menz 28 x10 for DA-100. 26 x 12 or 27 x 10 for 3W 80cc.
7

Tools
This is a very quick and easy plane to build, not requiring difficult techniques or special equip-
ment, but even the building of Composite-ARF aircraft requires some suitable tools! You will
probably have all these tools in your workshop anyway, but if not, they should be available in all
good hobby shops, or hardware stores like "Home Depot" or similar.
1. Sharp knife (X-Acto or similar)
2. Allen key set (metric) 2.5mm, 3mm, 4mm & 5mm.
3. Sharp scissors
4. Pliers (various types)
5. Wrenches (metric)
6. Slotted and Phillips screwdrivers (various sizes)
7. M3 tapping tool (metric)
8. Drills of various sizes
9. Small spirit level, or incidence meter.
10. Dremel tool (or Proxxon, or similar) with cutting discs, sanding tools and mills.
11. Sandpaper (various grits), or Permagrit sanding tools (high quality).
12. Carpet, bubble wrap or soft cloth to cover your work bench (most important !)
13. Car wax polish (clear)
14. Paper masking tape
15. Denaturised alcohol, or similar (for cleaning joints before gluing)
Adhesives and Solvents
Not all types of glues are suited to working with composite parts. Here is a selection of what we
normally use, and what we can truly recommend. Please don’t use inferior quality glues - you will
end up with an inferior quality plane, that is not so strong or safe.
High performance models require good gluing techniques. We highly recommend that you use
either a slow (minimum 30 minute cure) epoxy resin and milled fibre mixture, or a slow filled
thixotropic epoxy for gluing highly stressed joints (eg: Hysol 9462). The self-mixing nozzles make
it easy to apply exactly the required amount, in exactly the right place, and it will not run or flow
onto places where you don’t want it! It takes about 1 - 2 hours to start to harden so it also gives
plenty of time for accurate assembly. Finally it gives a superb bond on all fibreglass and wood
surfaces. Of course there are many similar glues available, and you can use your favourite type.
1. CA glue ‘Thin’ and ‘Thick’ types. We recommend ZAP, as this is very high quality.
2. ZAP-O or Plasti-ZAP, odourless, or ZAP canopy glue 560 (for clear canopy)
3. 30 minute epoxy (stressed joints must be glued with at least 30 min & NOT 5 min epoxy).
4. Loctite Hysol 9462 or equivalent (optional, but highly recommended)
5. Epoxy laminating resin (12 - 24 hr cure) with hardener.
6. Milled glass fibre, for adding to slow epoxy for stronger joints.
7. Micro-balloons, for adding to slow epoxy for lightweight filling.
8. Thread-locking compound (Loctite 243, ZAP Z-42, or equivalent)
8

We take great care during production and Quality Control at the factory to ensure that all joints
are properly glued, but of course it is wise to check these yourself and re-glue any that might just
have been missed.
When sanding areas on the inside of the composite sand-
wich parts to prepare the surface for gluing something onto
it, do NOT sand through the layer of lightweight glasscloth
on the inside foam sandwich. It is only necessary to rough
up the surface, with 80/120 grit, and wipe off any dust with
acetone or de-natured alcohol (or similar) before gluing to
make a perfect joint. Of course, you should always prepare
both parts to be joined before gluing for the highest quality
joints. Don’t use Acetone for cleaning external, painted,
surfaces as you will damage the paint.
Tip: For cleaning small (uncured) glue spots or marks off the
painted surfaces you can use old-fashioned liquid cigarette-
lighter fuel, like ‘Ronsonol’ or equivalent. This does not dam-
age the paint, as Acetone and many other solvents will, and
this is what we use at the factory.
At Composite-ARF we try our best to offer you a high quality kit, with outstanding value-for-
money, and as complete as possible. However, if you feel that some additional or different hard-
ware should be included, please feel free to let us know.
We know that even good things can be made better !
Did you read the hints and warnings above and the instructions carefully?
Did you understand everything in this manual completely?
Then, and only then, let’s start assembling your Composite-ARF Extra 260
9
TIP: Lighter fluid is excellent for
cleaning small marks, clear wax,
uncured glue, or similar off the
painted surface of the plane -
without damaging the paint.

Building Instructions
General Tips:
We recommend that you follow the order of construction shown in this manual for the fuselage,
as it makes access to everything easier and saves time in the end. The wings and stabs can be
done at almost any point, and only need servos and control horns installing anyway.
The first thing to do is protect the finished paint on the outside of the model from scratches and
dents during building - so cover your work table with a piece of soft carpet, cloth or bubble-plas-
tic. The best way to stop small spots of glue getting stuck to the outside of the fuselage is to give
the whole model 2 good coats of clear car wax first, but of course you must be sure to remove
this 100% completely before adding any decals or markings. Additionally you can cover the
majority of the fuselage with the bubble-plastic used to pack your model for shipping, fixed with
paper masking tape, which also protects it very well.
When sanding any areas of the inside of the fuselage to prepare the surface for gluing some-
thing onto it, do NOT sand right through the layer of glasscloth on the inside foam sandwich !
It is only necessary to rough up the surface, with 60/80 grit or equivalent, and wipe off any dust
with alcohol (or similar) before gluing to make a perfect joint.
Before starting construction it is a good idea to check inside the fuselage for any loose glass
fibres that could cut your hands, and a quick scuff over any of these with a coarse Scotchbrite
pad will remove them.
Note: It is very important to prepare the inside of the fuselage properly, by roughing up and
cleaning the surface, before gluing any parts to it.
Landing Gear
The 1st job is to fit the landing gear legs, and you can leave
these in place, as they will protect the bottom of the fuse-
lage during assembly and gear installation.
The Composite-ARF landing gear for the Extras consists of
45 deg laminated carbon fibre and fibreglass cloth and a
huge number of rovings inside, all made under vacuum and
heat-cured. However it is still light weight, and retains
enough flexibility to take the shock out of any landings that
are less-than-perfect!
The 4 undercarriage fixing bolts are installed from the out-
side, bottom, of the fuselage, as shown in photo P1.
Mark the position of the holes on each carbon
leg, and drill the holes with a sharp 6.5mm Ø
drill. The centres of the holes are measured
from the centre of the bend in the leg that will
be positioned about 8mm outside the fuselage
surface (photo P1). The outer holes are 33mm
from the bend, and the inner holes are 81mm
10
(above) The main parts used to
assemble the Landing Gear.
(below) Drill 2 x 6.5mm Ø holes for
bolting in the Landing Gear.

inside them. The centre of the holes should be 18mm from
the front edge of the carbon (photo above).
The legs are fixed to the plane with the M6 x 20 bolts and
13mm Ø washers into the blind nuts that are installed in the
plywood supports during manufacture (photo P2). Both
main legs are identical, until you have drilled the mounting
holes, and can be used either side.
The method of fixing the wheelpants and axles to the land-
ing gear legs is slightly different to the method we have
described in the past, but it is even easier and works bet-
ter. The wheelpants have a moulded-in recess for the end
of the landing gear legs, which also sets the correct angle
relative to the ground. Drill an 8mm Ø hole through the
moulded-in ‘dimple’ for the axle, and another 8mm hole
directly opposite, on the outside surface of the wheelpant
for inserting the axle bolt. You can spin the head of the axle
bolt against a sander to reduce the diameter a little if you
wish (see photo right).
Prepare the inner surface of the wheelpants by sanding the
kevlar patch. Take the 2 milled plywood ‘U’ shaped pieces
and enlarge the 6mm Ø holes to 8mm diameter. Press the
M6 T-nuts into the holes, just far enough so that the end of
the T-nut projects through the hole a maximum of 1mm.
The ‘spikes’ will still engage in the plywood, and the gap
between the T’ nut and the plywood is filled with epoxy and
microballoons mixture. (see photo P3)
Glue the 2 ‘U’ shaped milled plywood pieces to the inside
surface of the wheelpants with 30 minute epoxy and
microballoons mixture, over the kevlar reinforcement, in
line with the moulded recess, and so that the hole in the
plywood is exactly in line with the 8mm hole you have
drilled in the wheelpant. Temporarily use the LG mounting
bolts to secure the plywood to the wheelpant while the glue
dries. At the same time secure the T-nut to the plywood with
some of the thick epoxy/micro mixture, as shown.
Drill 6mm Ø through the centre of the moulded dimples in
the bottom of the carbon legs, and bolt to the wheelpants
temporarily with the axle bolt. You might need to sand the
ends of the carbon LG legs a little so that they fit into the
molded recesses in the wheelpants perfectly.
Bolt the LG legs to the wheelpants, and drill a 3mm hole
thru’ the carbon leg and wheelpant, about 25mm above the
axle. Fit an M3 bolt and washer, and use an M3 T-nut inside - also secured to the plywood ‘U’
shape with epoxy/micro mixture. This bolt sets the precise angle of the wheelpant to the carbon
landing gear leg. Do not use a bolt of larger diameter, as a larger hole required could weaken
the leg.
11
(above) Glue the milled plywood
reinforcements to the inside of the
wheelpant as shown, using a 30
minute epoxy and microbaloons
mixture.
(above) The moulded dimple in
the bottom of the carbon legs. Drill
a central hole of 6mm diameter.
(below) shows the M3 bolt thru’
the carbon leg, into the T-nut
glued inside the wheelpant.

Install your chosen wheels (Ø5” Dubro 500TL
shown), inserting the M6 x 70mm steel axle
bolt through the hole you drilled in the outside
surface of the wheelpant. Depending on the
thickness of your chosen wheel, you will need
2 or 3 of the M6 washers either side of the
wheel to centre it - and also an M6 wheel col-
lar (supplied) on the inner side as well,
between the washers and the ‘T’ nut.
Tighten the axle bolt securely into the T-nut,
and then secure the assembled wheelpant to
the carbon leg using an M6 washer and M6 locknut as
shown right. A drop of loctite on the M6 lock-nut is good
insurance. Finally insert the M3 bolt thru’ the carbon leg into
the T-nut.
You can use any 4.5” - 5" main wheels. Kavan wheels are
very lightweight, but not very durable on asphalt runways,
and Dubro wheels are a little heavier but much more solid.
Tailwheel
The tail wheel setup shown in these photos is an optional
part available from C-ARF (# 801000), and is mounted with
2 sheet metal screws and 2 plastic ‘U’ brackets under the
fuselage, screwed into the plywood reinforcement that’s
installed in the fuselage at the factory. Drill a 4.8mm diam-
eter hole, 55mm in front of the finpost and insert the tail-
wheel wire (photo right).
You don’t need to make the tailwheel steer-
able if flying from grass surfaces, a simple
castoring action is fine. However, for hard run-
ways you may prefer to connect it either to the
rudder horn with 2 small springs, or even bet-
ter to the rudder pull-pull cables about 130mm
in front of the rudder leading edge - as shown
here. It’s easy to make the springs, if neces-
sary, by winding some 0.5 - 0.8mm Ø piano
wire around a 5mm drill bit, turned slowly in a
battery-drill, with a small hook in each end to
connect to the tailwheel steering arms. (see
also photo P4)
Remember - keep it lightweight at the tail end!
12
(below) Tailwheel assembly
installed. It can be connected to
rudder horn OR rudder cables with
springs for improved steering.
(above) Completed wheel pant.
(below) Position of Ø 4.8mm hole
for C-ARF optional tailwheel.

Cowling
The 1 piece cowling is already cut and trimmed at the fac-
tory, and should need very little adjustment for a perfect fit.
With the main undercarriage legs bolted into place, install
the wing tube in the fuselage sleeve and place a small spir-
it or incidence meter level on top of it to set the plane exact-
ly level (side to side). Pack under one undercarriage leg as
necessary to get it level on your building table.
If necessary, sand the fibreglass joining tapes inside the
back edge of the cowl slightly to get a perfectly flush fit
between the cowling and the fuselage sides. Trial fit the
cowling, and use a straight-edge on the lower (flat) part of
the cutout at the front of the cowl to make sure that it is par-
allel with the wing tube, or stab, and properly centred. Tape
the cowl firmly into position, and mark a centreline on the
top of the cowl and the fuselage, on masking tape.
The cowling is held in place with 9 bolts (M3 x 12mm),
washers and blind nuts. Drill one 3mm diameter hole at the
top/centreline of the cowl, approx. 8mm (5/16”) in front of
the back edge of the cowling, and insert an M3 x 12mm
bolt. Thread a T-nut onto the bolt inside the fuselage, and
secure it to the fuselage with one small drop of thick CA.
Note that the blind nuts are fitted reversed, with the spikes
pointing inwards! Check alignment again, and then drill and
fit the other 8 bolts in the same way, securing the blind nuts
to the inside of the fuselage with a single drop of thick CA.
Space the 9 bolts 110mm (4.5”) apart, so that the lowest 2
bolts will be about 25mm from the edges of the square
cutout in the bottom of the cowling, to retain it properly.
Don’t forget to wax, or oil, the M3 bolts first, to make sure
that you don’t accidentally glue any of the bolts to the cowl-
ing or into the blind nuts! Finally glue the 9 blind nuts in
place properly using a medium-thick mixture of 30 minute
epoxy and micro-balloons, as shown. During final assem-
bly, add the supplied M3 washers under the heads of all the
M3 bolts.
13
(above) Check cowl opening is
parallel to stab or wing tube, and
tape in position.
(below) Secure with 9 equally-
spaced M3 x 12 bolts, into T-nuts
glued inside the fuselage.
(above & below) Tack glue the T-
nuts in position with a small drop
of thick CA first. When cowling is
correct, secure all the T-nuts with
a drop of, fairly wet, epoxy and
microballoons mixture as shown.
M3 T-nut
M3 bolt
cowl/fuselage
Epoxy
& micro
mixture.

Canopy Frame
The fibreglass canopy frame mountings are already com-
pleted for you at the factory. It is secured to the fuselage
with four M4 x 10mm allen bolts, fitted from the outside of
the fuselage, through the plywood tabs that are glued to the
canopy frame, into M4 T-nuts. This system has been very
well proven on all of our aerobatic planes, and is a strong
and rigid solution.
Fitting the clear canopy into the frame can be a little bit
tricky, and this is a step by step guide of how we do it. Of
course you can use own your favourite glue and method if
you prefer.
Sand the inside edges of the canopy frame carefully with
120 grit sandpaper, especially the fibreglass joining tapes,
to ensure a perfect fit of the canopy. Fit the canopy frame
on the fuselage and secure with all 4 bolts. Lay the canopy
on top of the frame, view from the front to check that it is
centred and symettrically positioned, and then mark the
approx. shape with a felt pen or wax crayon. There is an
approx. ‘cut-line’ molded into in the edges of the canopy to
assist you, and you should start by trimming 4 - 6mm out-
side this line. Unless you are in a very warm room, we rec-
ommend that the canopy is slightly warmed up with a hair
dryer to prevent cracking - but be careful not to melt or
deform it! When the canopy fits inside the frame, tape it
into position temporarily, and accurately mark the edge of
the frame on the canopy with a wax crayon. Remove the
canopy and trim exactly to shape, leaving about 6mm over-
lap outside the line all around.
Refit the canopy into the frame, and tape into position from
the inside. Push the canopy up tightly inside the back of the
frame and fix the bottom 2 back corners with
one small drop of odorless CA each (ZAP-O
recommended).
Note: Do NOT use any CA accelerator/kicker
- you will immediately ‘fog’ the clear canopy!
Make visual check from the front and back to
make sure sure that the canopy is straight.
Make several hand-holds with strong tape to
make holding and positioning the canopy
easy. Remount the frame to the fuselage (use
all 4 bolts), and tape the canopy frame tightly
to the fuselage all around.
Tip: The sides of the fuselage and canopy frame are almost straight and so, if you wish, you can
temporarily stiffen the edges of the canopy frame (while gluing the canopy in) by tacking some
14
(above) Mark centrelines on the
clear canopy at front and back and
visually check that it is straight.
(below) Duct-tape handles used to
pull clear canopy against the
canopy frame while gluing it in
position with a few small drops of
odorless-CA. Remove canopy and
secure the edges of the clear
canopy with a bead of epoxy to
trap it in place (see above)
(above) The canopy frame is
secured to the fuselage with 4
tabs, M4 bolts and T-nuts, all fin-
ished at the factory for you. Also
note the bead of epoxy to secure
the canopy to the inside of the
fibreglass frame.

strips of 10mm balsa to masking tape on the fuselage sides. This makes it easier to pull the clear
canopy against the frame, using the tape ‘handles’ while tacking it in to place - without deform-
ing the canopy frame.
Using the tape handles to pull the canopy outwards firmly against the frame, working from the
back towards the front, glue the edges of the canopy in place in 2 more places each side, with
just a single small drop of CA at each position, all the time checking that the edge of the canopy
is tight up against the frame at the front.
Now that the canopy is fixed in position and cannot twist or warp anymore, you can carefully
remove the canopy frame from the fuselage, and use a 30 minute or 24hr epoxy and micro-bal-
loon mixture for gluing all the edges to the frame on the inside surface (see photo above). It is
most important that the canopy cannot come off in flight, so make sure that the bead of glue traps
the clear canopy firmly in place. Re-secure the canopy frame onto the fuselage with all 4 bolts
while the epoxy-microballoons mixture is curing to prevent any warps or twists.
If you want a completely rattle-free canopy, you can fill the slight gaps at the front and back of
the frame with a bead of clear silicone. Apply shiny brown plastic tape to the front and back
edges of the opening in the fuselage and wax twice with clear car wax. Sand lightly, and de-
grease edges of canopy frame where the silicone will be applied. Apply a small bead of clear sil-
icone to the front end of the frame only, and secure the frame into position wthl all 4 bolts until
cured. Remove frame, and trim off excess silicone with a very sharp knife. Then repeat for the
back edge. Do not try to do the back and front at the same time - or you will find it very difficult
to get the canopy frame off the fuselage! See photo P5.
If you wish you can tint the inside of the canopy using one of the aerosol spray paints used for
painting the inside of polycarbonate car bodies (eg: the Tamiya or Lexanit ranges). Degrease and
clean the the surface very carefully, removing all finger-prints, and use many very light ‘mist’
coats to get even coverage.
Horizontal Stabs
The stabilisers are 95% finished at the factory, and only need the servos, horns and linkages
installing. Insert the Ø20 x 330mm long aluminium tube spar in the fuselage sleeve, and slide on
both stabs to check the fit between the root ribs and
the fuselage. You can sand the root of the stabs
slightly to make a perfect joint if needed, and if the
spar tube is a fraction long you must shorten it.
The elevators are hinged to each stab using the Ø
4mm aluminium tubes provided. Make sure there is
no burr on either end of the tubes, and chamfer one
end slightly with fine sandpaper to make it easier to
get them through the holes in the phenolic hinge
plates. Be careful inserting them, and if they are a bit
stiff, then use a little grease on the tubes. Don’t use
too much force, otherwise a phenolic hinge post
inside might break loose. Leave the tubes a bit too
long during assembly, and cut them to exact length
when the model is finished.
15
(above) Bell/splay one end of each tube,
countersink the hole in the root end of
the elevator, & use clear tape to fix the
tube in position during final assembly.

During final assembly, you can retain both ends of the
tubes with small pieces of clear tape on the root and tip
ends of the elevators. An alternative method is the ‘bell’ one
end of each aluminium tube, and countersink the hole in the
root end of the stab. Then you only need to tape the inner
end of the hinge tube (photo above).
Servos
You have a choice of elevator servos; either a hi-power dig-
ital JR8511/8611 in each stab, or an JR8411, which is also
sufficient. Although the JR8511/8611 servos are about 1
mm longer and wider than the 8411, both sizes will fit in the
milled servo cutouts in the ribs. If using Futaba servos, we
recommend that you use S9351’s, which also fit the milled
servo cutouts. Please do not use inferior quality servos, or
servo arms, in this plane. It will result in an aircraft that does
not fly accurately, reliably or safely.
The servos are installed with the output shafts towards the
stab trailing edge, and they must be installed using the
2.9mm Ø x 13mm sheetmetal screws provided in the kit,
not the standard screws provided with the servos which are
too small for the Ø 2mm milled holes.
Servo arms
To obtain sufficient elevator throws, quite long servo output
arms are needed (30 - 35mm/1.25 -1.5”). In the kit we sup-
ply phenolic servo arm extensions for this purpose, which
can be fitted onto your servo output discs to achieve the
throws. However, it is mandatory to secure these to metal
servo output discs, or to use full metal servo arms (like
those shown below from SWB) - and not the standard plas-
tic output discs supplied with the servos. The extreme
torque of the current hi-torque digital servos can strip the
plastic splines from the inside of the disc - which will result
in immediate flutter and destruction of your Extra. Several
reputable accessory companies make aluminium discs and
servo arms, but you should check that the CNC machined
splines fit onto the servo output shaft tightly, with a mini-
mum of lost movement/play.
Secure the phenolic arms to the servo output discs as follows: Fit the metal discs to the servos.
Centre both elevator servos using your R/C and attach the phenolic servo arms to the outside of
the metal discs temporarily with a couple of drops of CA, making sure that the servo arms are
both at 90° to the bottom surface of the stabs using a set square. Then remove the arms and
discs, drill through both, and secure with at least 2 small bolts, washers, locknuts and Loctite (M2
bolts and nuts included). Add a drop of Loctite to the bolt that secures the discs to the servos.
Use this same method to attach the phenolic extension arms to metal discs for the aileron &
rudder surfaces also.
At Composite-ARF we only use the aluminium ‘Double-Loc’ servo arms from SWB manufactur-
16
(above) Servo is screwed into the
milled cutout in the inner rib.
*
(above) If you use the phenolic
servo arm extensions, you MUST
bolt these to metal servo discs.
(below) The alternative is full metal
servo arms, such as these SWB
‘Double-Loc’ types that we use on
most of our factory planes.

ing (USA) and we highly recommend them. These arms
clamp onto the servo output shaft with no lost movement
(play) at all. These are high quality, properly engineered
arms, and are available from many good hobby stores.
With your chosen servo arm secured to the servos, fit them
in place in the milled cutouts in the stabs and secure with
the 2.9 Ø x 13mm sheetmetal screws we have included.
It is most important that the linkage from the servo arms
is exactly in-line with the phenolic control surface horns in
the elevators, as any ‘side-load’ or ‘twisting’ could weaken
or even break them, causing flutter and destruction of your
Extra. If you have chosen to fit full metal servo arms, (eg:
SWB), you can fit a single-sided ball-link onto the servo arm
to adjust the line of the linkage if necessary - but you must
not fit a ball-link to a phenolic or plastic servo extension
arm, or phenolic control surface horn.
If your chosen servo arm system does not line up perfectly
with the factory-milled slots for the phenolic control horns,
you can either fill the slots and mill new ones - or even pack
the servo off the rib slightly inside the stabiliser (with thin
plywood) to adjust the alignment. Make up the elevator link-
ages from the hardware supplied, using M3 x 45mm
threaded rods, and M3 steel clevises and nuts at both ends.
If you use a full metal servo arm, then you may need to use
a wider clevise with a separate pin and E-clip, because of
the thickness of the arm and the sizes of the holes - as
shown on the SWB arms here. This also applies to the
aileron horns, of course.
Control Horns
The slots for the phenolic elevator control horns are already
partly milled in the elevators for you, and may be adjusted
or repositioned if required. Extend the slot for the elevator
horn to least 20mm deep, using a Dremel mill or small
Permagrit file, checking alignment with the servo arm/link-
age as you work. Trim the length of one of the phenolic con-
trol arms so that the hole for the clevise is approx. 25mm
from the surface of the elevator, and rough-sand the part
that will be glued into the balsa block inside the elevator.
Ideally the hole in the horn for the clevise should be exact-
ly perpendicular to the centre of the hinge tube.(see P7)
Wax the area with clear car wax, cover with a layer of plas-
tic parcel tape over the area of the milled slot, re-wax the
tape carefully, and then cut through the tape with a very
sharp knife to allow the horn to be glued into the slots. The
tape stops excess glue getting on the painted elevator, and
makes the clean-up easy and quick.
17
(above) Elevator horn alignment
template from scrap plywood. Line
is hinge tube axis. Use for both ele-
vators to ensure same throws.
(below) Stab retaining bolt, with
clear tape over it secure for flight.
The small pieces of tubing stop the
quick-links from opening.
(above) You can ONLY use a ball-
link on a full metal servo arm to
adjust linkage alignment. Do NOT
use on phenolic arms or horns.
(below) Use brown parcel tape
and a coat of clear wax to protect
paint & make easy clean-up when
gluing in all control surface horns.
(NB: Extra 300SX shown here)

Make up the servo linkage from the hardware provided, and connect your servo arm to the con-
trol horn, which helps to hold the horn in exactly the correct position while the glue cures. Fill the
slot in the elevator with slow epoxy and micro-balloons (at least 30 minute cure), or a thixotrop-
ic resin like Loctite Hysol 9462, insert the horn, and then wipe away excess glue. Check that it
is aligned perfectly with the linkage, the clevise hole is 25mm from the surface of the elevator,
and is perpendicular to the hinge axis. View from the back or front to check that the horn is at 90
degrees to the surface of the elevator. See photos P6 and P7 for ideal linkage.
When cured, remove the plastic parcel tape and make a template, as shown above, so that you
can copy the position to the horn on the other elevator. In this way you will get exactly equal ele-
vator throws without lots of mixing and linkage adjustment when setting up your plane. You can
make the template from scrap plywood, and use an old 1.5mm (1/16”) drill bit to insert into the
clevise hole, secured with a drop of CA. Using the template, glue the horn into the other eleva-
tor in exactly the same way.
The linkages between the servo arms and elevator horns are made from the 45mm x M3 all-
thread, with 2 steel clevises and 2 x M3 nuts for each stab. ‘Loctite’ the quick-link and lock-nut
on one end of each linkage. If using full metal arms, like the SWB arms shown, you will need to
replace the steel clevise on the servo end with a larger type as shown here. If using clevises with
aluminium pins in aluminum servo arms, we highly recommend that you apply a little grease on
these joints to give smooth movement and prevent any chance of the aluminium pin binding in
the servo arm hole.
Use this same technique described above, using templates for the inner/outer aileron horns.
Throws
If you need more travel on the elevators than the factory
assembly allows (about 40°) you will need to increase the
length of the slots in the composite/balsa false leading
edge of the elevators with a small file. The outer 2 slots in
particular will need to be longer, and you can extend them
almost right out to the composite skin. Unfortunately it’s not
possible for us to mill these slots longer during manufacture
- as the L.E. spar would fall apart on the CNC milling table.
However, this is a very quick job with a Permagrit file, or
similar (see photos right), and you can easily achieve 50
degree throws if you wish.
Note: Several photos of the stabs in these instructions
show the 1.5” SWB arms on JR8511 servos, with the cle-
vise in the outer hole - and this was used for extreme test-
ing of the model and stabiliser servo system, with more
than 50 degrees throw possible.
Stab Tube
The last job is to fit the M3 stab retaining bolts. Inside the
stabs you will see the small ply reinforcement plates
between the spar sleeve and the bottom surface of the
stab. Mark the bottom of both stabs in the centre of this ply-
wood. Install the aluminium tube into 1 stab, and drill a
2.4mm hole right through the stab surface, the plywood
plate, fibreglass sleeve and the 20mm aluminium tube. The
18
(above/below) You can increase
available throws by lengthening
the slots in the leading edge of the
elevators, especially the 2 outer
slots. Use a fine flat file, such as a
Permagrit, and be careful not to
make the slots any wider. (Extra
300SX elevator shown)
*

centre of the hole will be 26 - 28mm from the stab T.E.
Thread the hole with an M3 tap and secure it with an M3 x
16 bolt. Then glue an M3 blind nut (included) inside the
spar tube, with some 30 minute epoxy and micro-balloons.
Wax or oil the bolt first! Fit both stabs to the fuselage, check
that they fit tightly to the fuselage at the roots, and then drill
the hole in the other stab and spar tube, and tap the thread
as before. Counterbore the holes in the bottom surface of
the stabs for the boltheads so that they sit flush on the
small plywood plates.
TIP: Try to always leave the stab tube fixed into one stab,
and never remove that one bolt, as it is difficult to find the
right position for the stab tube again if it is removed from
both stabs!
Rudder
Trial fit the the double-sided phenolic control horn in the slot
that is already milled in the base of the rudder, mark the
central part that will be glued in, and scuff it well with coarse
sandpaper. There is a balsa block above the horn position
inside the rudder, and this should also be scuffed with
sandpaper or a small file. Adjust the milled slot in the rud-
der so that it is a little higher than the phenolic control horn
thickness, so that all the glue is not scraped off the horn
when you insert it into the rudder !
Cover the rudder both sides around the slot area with
masking tape, wax the area, and then cut through the tape
to expose the slot with a sharp knife - in the same way as
described for the elevators. You can also protect the out-
sides of the phenolic horn with tape, and this makes it easy
to clean off excess glue afterwards. Glue the horn in posi-
tion with slow (min. 30 minute) epoxy & micro-balloon mix,
making sure that it is perfectly centred and level in the rud-
der. (Photo P8.)
When the glue has cured, fit the rudder to the vertical sta-
biliser with the Ø 4mm aluminum hinge tube. Check for
smooth movement. You can increase the lengths of the
slots in the rudder L.E. in same way as for the elevators for
extra throw if necessary.
The rudder servo mounting tray can be installed in 2 different positions, and the milled parts are
supplied for both options. If using a lightweight engine, such as the 3W shown here, you will def-
initely need to install the rudder tray as far forward as possible for correct Centre of Gravity,
against the back of the landing gear mount. If using a 100 - 125cc twin, then you may be able
19
(above) Scuff up the gluing sur-
faces on the phenolic rudder horn
and glue into the slot in rudder.
(below) The Tank base/Rudder tray
is assembled from the milled parts
included. Shown here with the
bulkhead glued to the front of the
tray, for fitting in the rear position
(for large motors)
(below) M3 blind nut glued into
elevator spar tube.

install it at the back of the cockpit, as shown in the photo
right, but this will also depend on the weight and position of
your batteries and exhaust system.
Assemble the tray and install the servos and phenolic arms
outside the model, and decide which position you will install
it in. Lightly sand all composite balsa milled parts, and glue
together with thin CA. Add the 3mm thick plywood strips
underneath each servo rail, cut from the 12mm wide ply
strips provided. Then reinforce all joints with 30 minute
epoxy. (see photo P9)
Servos
The recommended choice of servos is similar to that for the
elevators, either a pair of JR/Graupner 8411/8511/8611’s or
a pair of Futaba S9351’s.
Servo arms
The supplied phenolic rudder servo output arms must be
bolted to 1” or 1.25” diameter metal servo output discs in
the same way as the elevators. We used ‘Hangar 9’ #
3520’s. Please do not use the standard plastic discs for
this, as there is a chance that the internal plastic splines
can be stripped by the current hi-torque servos - causing
instant rudder flutter, and probable loss of your plane.
Fit the 2 rudder servos into the tray, with the output shafts
nearest to the tailplane, and screw into position using the
2.9mm Ø x 13mm long sheet-metal screws supplied. Fit the
metal servo discs, and centre both servos using your R/C.
Rough sand and clean the bottom surface of the 2 pheno-
lic horns, and the top of the metal discs.
With the R/C still switched ‘ON’, place the C-ARF rudder
servo horns on top of the output discs, with the ‘hooks’ of
the back arm facing forwards, and align them exactly paral-
lel. Tack glue the phenolic arms on top of the output discs
with a couple of drops of thick CA. When the glue has
cured, remove the arms and discs, drill through both and secure with at least 2 small bolts, wash-
ers, locknuts and Loctite (M2 bolts and nuts included). Finally add a drop of Loctite to the bolts
that secure the discs to the servos.
Make up the linkages between the phenolic 2 arms from the M3 ball-links, threaded rod and steel
clevises included, as shown above. You will need to drill the inner holes on the back arm out to
3mm diameter for the M3 x 16mm bolts that secure the ball-links. Fit just one of the linkages
between the phenolic arms, and adjust the length of the linkage very carefully until so that there
is minimal buzzing or humming from the servos at idle, and at full throw. When satisfied, add the
other linkage and follow the same method of adjustment.
Install the completed tray in the fuselage, prepare the area for gluing with sanding, and glue the
assembly in position with at least 30 minute epoxy. Fit the small balsa sub-bulkhead to the back
of the tray if in the forward position, or the front if the tray is in the rear position (photo P10).
20
(above) Make sure that the pheno-
lic arms are parallel when you glue
them onto the discs.
(below) Scuff the discs and arms
before gluing. Secure with at least
two M2 bolts provided.
(above) Rudder tray and sub-bulk-
head shown in the (optional) rear-
wards position.
Table of contents
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