Composite-ARF Extra 260 User manual

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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]
or [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.
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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-
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NO !!!
Secure the plane
before starting the engine.
DANGER ZONES
NO NO

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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
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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.
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(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.
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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)
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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.
Email us: [email protected].
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
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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
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(above) The main parts used to
assemble the Landing Gear.
(below) Drill 2 x 6.5mm Ø holes for
bolting in the Landing Gear.