SIG MAYHEM 40 User manual

All servos should be standard size dimensionally to fit in the
openings provided in the aircraft structure.
Note: The large control throws used in 3D flying require a servo
with precise centering capability. You can not expect this airplane
to give you optimum 3D performance using non-ball bearing
standard servos.
Servo Chords Needed:
Ailerons - one standard y-harness
Elevator - one 12" servo extension chord
Rudder - one 12" servo extension chord
ENGINE SELECTION
The MAYHEM has been designed to perform well when using the
recommended engine sizes. Do not use an engine larger than
recommended. Recommended Engines:
.40 to .46 cu.in. 2-Stroke
.52 to .70 cu.in. 4-Stroke
Very Important: The MAYHEM 40 is designed for slow speed,
high torque aerobatics. It's fantastic low speed maneuverability is
the result of light weight and very large control surfaces - which are
naturally prone to flutter if flown at excessive airspeeds. To avoid
problems, follow these carefully tested guidelines:
1) Do not use engines larger than recommended. Resist the
urge to overpower your MAYHEM 40 with larger engines, which
can cause balance and structural problems, and produce
excessive airspeed.
2) Do not use a propeller with more than 6 inch pitch. Keep the
airspeed of the MAYHEM down by using low pitch propellers.
3) Do not fly full throttle except during climbs of at least 10
degrees. Always throttle back when in a dive.
Ignoring these cautions will put your model at high risk for
catastrophic in-flight structural failure.
REQUIRED TOOLS
For proper assembly, we suggest you have the following tools and
building materials available:
A selection of glues - thin, medium, and thick SIG CA, and
SIG Epoxy Glue (5-minute and 30-minute)
Threadlock Compound, such as Loctite®Non-Permanent Blue
Silicone Sealer - clear or white
Screwdriver Assortment
Pliers - Needle Nose & Flat Nose
Diagonal Wire Cutters
Small Allen Wrench Assortment
Drill with Assorted Drill Bits
Pin Vise for Small Dia. Drill Bits
Hobby Knife With Sharp #11 Blades
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INTRODUCTION
Congratulations on your purchase of a SIG MAYHEM 40 ARF. This
is not your average R/C aerobatic flyer! Properly assembled,
powered and flown, the MAYHEM 40 can take you into the exciting
world of 3D aerobatic flying. Generous wing area, lightweight
construction, and huge control surfaces with large amounts of
travel, enable the MAYHEM 40 to perform the extreme 3D
maneuvers you've been reading about … hovering, harriers,
waterfalls, blenders … the MAYHEM 40 can do them all.
NOTE: The MAYHEM 40 is not suitable for beginners. While it is
a terrific flying airplane, it's neutral stability and quick controls are
beyond the capabilities of beginning R/C pilots. You should be
capable of flying low-wing, aileron equipped R/C models before
flying this airplane.
EASY TO ASSEMBLE
The MAYHEM 40 ARF has been engineered to get you into the air
as quickly as possible with an R/C model that compares to the
best scratch-built airplanes. The airframe has been expertly
constructed of the finest balsa and plywood available, then
professionally covered with tough SIG AEROKOTE™ polyester
film. The airplane is both rugged and easy to repair.
This assembly manual has been sequenced to get your MAYHEM
assembled and into the air very quickly. We strongly suggest that
you read through the manual first to familiarize yourself with the
various parts and assembly sequences. The successful assembly
and flying of this airplane is your responsibility. If you deviate from
these instructions, you may wind-up with problems later on.
RADIO EQUIPMENT
The MAYHEM 40 requires a 4 (or more) channel radio system
with five servos. We highly recommend the use of a modern
programmable computer radio. Such radio systems allow you to
easily set and adjust every channel and additionally program
various flight functions to suit your individual style of flying.
Servo Requirements:
Ailerons - two(2) standard or high performance servos
Elevator - one(1) standard or high performance servo
Rudder - one(1) standard or high performance servo
Throttle - one(1) standard servo
Standard vs High-Performance Servos?
Standard servos with 45-55 in/oz of torque will fly the MAYHEM 40
with no problem, including basic pattern-style aerobatics. However
if 3D flying is your goal, you should consider upgrading to extra
high speed ball bearing servos for the ailerons, elevator, and
rudder (we used Hitec HS925MG high speed ball bearing servos
in the prototype shown in this manual).

Scissors
Covering Iron and Trim Seal Tool
Masking Tape
Paper Towels
Power Drill With Selection of Bits
Dremel®Tool with Selection of Sanding and Grinding Bits
Soldering Iron and Solder
Large Fuel Tubing
KIT CONTENTS INVENTORY
The following is a complete list of all parts contained in this kit.
Before beginning assembly, we suggest that you take the time
to inventory the parts in your kit, using the check-off boxes ❑
provided. Note that the CA type hinges for the ailerons, rudder,
and elevators are not glued in place. You will glue them during the
assembly process. Also, note that the nuts and bolts required to
mount your engine to the motor mounts are not included in this kit
and must be purchased separately.
Note: The following abbreviations are used in the descriptions of
bolts and screws in this list.
SL = Slotted-Head
SC = Socket-Head
PH = Phillips-Head
PWA = Phillips Washer Head
BASIC AIRCRAFT PARTS (covered with AEROKOTE™)
1 bag ❑(1) Right Wing Panel
❑(1) Right Aileron
❑(5) CA Hinges (not glued)
1 bag ❑(1) Left Wing Panel
❑(1) Left Aileron
❑(5) CA Hinges (not glued)
1 bag ❑(1) Stabilizer & Elevator Set, with
❑(6) CA Hinges installed but not glued
1 bag ❑(1) Fin & Rudder Set, with
❑(3) CA Hinges installed but not glued
1 bag ❑(1) Fuselage, with
❑(1) Clear Plastic Canopy
❑(6) M2 x 8mm PWA Screws, for canopy mounting
❑(1) Fuselage Bottom Fairing
❑(2) 1/4-20 Blind Nuts installed, for wing attachment
❑(2) M4 Blind Nuts installed, for l.g. attachment
❑(1) Fuel Tank Hatch
❑(2) M2 x 8mm PWA Screws, for hatch mounting
OTHER_PARTS:
1 bag ❑(1) Fiberglass Cowling
❑(5) M2.6 x 8mm PWA Mounting Screws
1 bag ❑(1) Right Fiberglass Wheel Pant
❑(1) Left Fiberglass Wheel Pant
❑(1) Aluminum Main Landing Gear
❑(2) M4 x 15mm PWA Bolts
❑(2) M4 Split Lock Washers
❑(2) 2-1/4" dia. Main Wheels
❑(2) M4 x 34mm PWA Axle Bolts
❑(4) M4 Lock Nuts
❑(2) M4 Hex Nuts
❑(4) M3 Split Lock Washers
❑(4) M3 x 10mm PWA Bolts
❑(1) 1" dia. Tail Wheel
❑(1) Tailwheel Assembly:FormedWire, Mounting Bracket,
and Wheel Collar w/ Set Screw
❑(4) M2 x 10mm PH Screws
❑(1) Wheel Collar w/ Set Screw
1 bag Fuel Tank Assembly
❑(1) 260cc (8.8 oz.) Plastic Tank
❑(1) Rubber Stopper
❑(1) Metal Front Clamp
❑(1) Metal Rear Clamp
❑(1) M3 x 19mm PH Clamp Bolt
❑(1) Metal Clunk Pickup
❑(1) Fuel Pickup Tubing, for inside tank
❑(1) .118" od x 1-9/16" long Aluminum Tube
❑(1) .118" od x 2" long Aluminum Tube
❑(1) .118" od x 2-3/8" long Aluminum Tube
1 bag 2-1/4" Dia. White Spinner Assembly
❑(1) Plastic Spinner Cone
❑(1) Plastic Spinner Backplate
❑(1) Plastic Prop Shaft Adapters
❑(2) Screws
1 bag ❑(4) Nylon Control Horns and Retainer Plates
❑(8) M2 x 15mm PH Bolts
❑(2) Wire Aileron Pushrods
❑(1) Wire Elevator Pushrod
❑(1) Wire Rudder Pushrod
❑(4) Metal R/C Links
1 bag Throttle Pushrod Assembly
❑(1) 1/8" od x 12-1/2" Plastic Pushrod Tube
❑(1) 3/16" od x 11-3/8" Plastic Pushrod Sleeve
❑(2) M2 x 7/8" long Threaded Studs
❑(2) Metal R/C Links
1 bag ❑(2) Glassed-Filled Engine Mounts
❑(4) M3 x 20mm PH Bolts
❑(4) M3 Blind Nuts
❑(4) M3 Flat Metal Washers
❑(4) M3 Split Lock Washers
1 bag ❑(1) Hardwood Wing Joiner
❑(2) 1/4-20 x 1-1/2" Nylon Wing Bolts
❑(2) Fiberglass Wing Bolt Guides
❑(1) Plywood Wing Bolt Plate
❑(1) Plywood Throttle Pushrod Support
❑(1) 5/16" x 1/2" x 2-7/8" Balsa Stick,
for fuel tank rear support
MISCELLANEOUS:
❑1 Each #SIGDKM298 MAYHEM 40 Decal Sheet
❑1 Each #SIGIB298 MAYHEM 40 Assembly Manual
COVERING MATERIAL
Your MAYHEM 40 ARF has been professionally covered with SIG
AEROKOTE™ polyester film covering.
The colors are: # STL100 White
# STL311 Red
# STL250 Blue
# STL201 Black.
You may notice that some wrinkles might develop in the covering
after removing the parts from their plastic bags. If that is the case,
there is no need to be alarmed. This is perfectly normal in low
humidity climates. Your model was built and covered in a part of
the world with relatively high humidity and therefore the wood was
likely carrying a fair amount of moisture. When exposed to drier air,
the wood typically loses this moisture, dimensionally "shrinking"
slightly in the process. In turn, this causes the wrinkles.
Any wrinkles that appear in the covering material are easy to
remove by using a standard hobby-type heat iron. We suggest
covering the iron's shoe with a thin cotton cloth, such as an old
T-shirt, to prevent scratching the covering film.
Set your iron to 220OF - 250OF (104OC - 121OC).
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First, use the heated iron to go over all the seams and color joints
in the covering, making they are all sealed down and well adhered.
Then use the heated iron to lightly shrink the material - do not
press on it. Once the covering is tight, lightly iron the material back
down to the wood. You can also use a hobby-type heat gun to
re-shrink the covering, but you must be extra careful around the
seams. Re-heating seams may cause them to "creep", making
them unsightly.
MODELER'STIP: One of the most common problems associated
with shrinking any covering film is controlling the heat around
seams. Heat applied close to or directly onto seams re-heats the
covering adhesive and the seam will often "crawl". This is easy to
control. Just tear a few paper towels into strips and soak them in
cool tap water. Lay the wet strips over any covering seam and use
your heat gun or iron as you normally would. The wet strips keep
the seam cool while the covering immediately next to it shrinks.
WARPS!
Light weight is a key ingrediant in the MAYHEM'S flight profile.
Because of their light weight construction, the ailerons, elevators,
and rudder of the MAYHEM can become warped whenever the
covering material is heated for shrinking. Care must be used to
make sure that the control surfaces remain straight as the covering
cools. Avoid putting a twist in the part while taking out wrinkles.
If you find a warp in one of your parts, the warp can almost always
be removed by twisting the surface in the opposite direction and
holding it there while heat is applied to the covering material. After
the covering cools, release the control surface and recheck for the
warp. The amount of reverse twist and heat that you apply, will
determine where the control surface ends up after it cools.
Note: When trying to remove a warp, an extra set of hands are
needed. Have someone assist you. While one person holds the
reverse twist in the control surface, the other person applies the
heat by passing a covering iron over both sides of the part.
WING ASSEMBLY - OVERVIEW
The wing of the MAYHEM comes in two pieces, a right wing panel
and a left wing panel, which will be permanently glued together to
make a strong one-piece wing.
For precise control of the ailerons, there is one aileron servo
mounted in each wing panel.
To avoid unnecessary dents, dings, or scuffing of the airplane
parts, we suggest that you cover your workbench with a soft
household blanket or foam sheet while assemblying your model.
WING ASSEMBLY, PART I: Joining the wing panels
For the following steps you will need these parts:
• 1 - Right Wing Panel
• 1 - Left Wing Panel
• 1 - Hardwood Wing Joiner
❑ 1) Trial fit both wing panels onto the Hardwood Wing Joiner.
Check to see that the wing panels fit together in proper alignment,
and that both root ribs come into firm contact with each other. If
the Hardwood Wing Joiner requires a little trimming to achieve this
fit, do so now. When satisfied with the fit, take back apart.
❑ 2) Use slow drying epoxy glue to permanently join the two wing
panels together. Apply the glue generously to the end ribs, Work
some glue into the joiner slots, and coat the joiner itself.
Carefully slide the wing panels together on the joiner. Press them
together tight. Wipe away any excess epoxy that oozes from the
joint with a paper towel or a rag dampened with rubbing alcohol.
Be careful that the leading and trailing edges of the two wing
panels are perfectly aligned and that there is no built in twist.
Secure the joint in perfect alignment with tape until the glue dries.
NOTE: It's very important to use plenty of epoxy when gluing the
wing panels together. The strength of your wing joint depends on
it! Don't worry if the excess glue oozes out and gets on the

4
covering material. With slow-drying epoxy, you will have plenty of
time to clean up all the glue smears with a paper towel soaked in
rubbing alcohol. Also, if possible get someone to help you with this
proceedure. An extra set of hands makes the job much easier!
While one person is holding the wing panes tightly together, the
other person can wipe off the excess glue.
WING ASSEMBLY, PART II: Installing the aileron servos
For the following steps you will need these parts:
• 1 - The Wing Assembly
• 2 - Aileron Servos (not supplied)
• 1 - ServoY-Harness Chord (not supplied)
Note: On the top side of the wing, on each side of the center joint,
you will find two round holes. Inside each hole you will find a short
length of wood with a string tied to it. Likewise, inside the aileron
servo bays on the bottom of the wing you will find similar wood
pieces with strings tied them. These are the other ends of the
strings you saw at the center of the wing. These strings will be
used to pull the aileron servo wires through the wing panels in the
following steps.
Working on one wing panel at a time...
❑ 1) Start at the center hole and gently break the wood piece loose
from the wing structure. Pull the wood piece and the string a few
inches outside of the wing. Remove the wood piece from the string
and disgard it. Tie the end of the string securely to the end of one
of the two servo leads of yourY-Harness Chord, as shown.
❑ 2) Go to the aileron servo bay on the same side of the wing and
break that wood piece loose from the wing structure. Carefully pull
the string and the attachedY-Harness lead through the wing panel,
until the plug on the end of the wire comes out of the opening in
the servo bay. Be sure you don't pull all of theY-Harness inside the
wing - leave the other two plugs of the Y-Harness outside at the
center of the wing.
Note: You may occasionally feel like the wire has become stuck
inside the wing. This is simply the plug on the end of the servo
wire hitting the side of the holes in the wing ribs. Gently work the
string back and forth from both ends until the plug fits through the
hole. Sometimes the servo plug comes through all the ribs the first
time without getting hung up, and other times it seems like it gets
hung up on every rib. Be patient and don't try to force it. The holes
in the ribs are large enough to get any common servo plug
through. Sometimes it helps to hold the wing panel vertically and
shake it slightly while pulling lightly on the string.
❑ 3) Once you can get a grip on the Y-Harness plug at the servo
bay, connect your aileron servo to the plug. Tape the connection
so it can't ever come loose inside the wing. Then untie the string
from the wire and dispose of it.
❑ 4) Now feed the wire back inside the wing by carefully pulling on
the other end of the Y-Harness where it exits the top of the wing.
Keep pulling the wire back towards the center section until you can
fit the aileron servo into the plywood servo mount that is built into
the wing panel. Note that the servo should be positioned so that
its output arm is at the rear end, toward the trailing edge of the
wing. Use a small drill bit to drill pilot holes in the servo mount for
the servo mounting screws. Use the screws supplied with your
radio system to mount the servo in place on the servo mount.
Repeat these steps to mount an aileron servo in the other side of
the wing.

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WING ASSEMBLY, PART III: Hinging the ailerons
For the following steps you will need these parts:
• The wing assembly
• 1 - Right Aileron
• 1 - Left Aileron
• 10 - CA Hinges (5 per aileron)
❑ 1) Start by inserting CA Hinges into the 5 slots in the trailing
edge of one side of the wing. Slide the hinges HALFWAY into each
hinge slot. DO NOT GLUE THE HINGES AT THIS TIME!
❑ 2) Now install the aileron onto the exposed half of the hinges.
It's easiest to slip the aileron onto the hinges at angle, one hinge
at a time, instead of trying to push it straight onto all the hinges at
once. Start at the wingtip, inserting the end hinge into the end slot
in the aileron. Once you have that hinge started, move to the next
hinge and get it started into its slot. Move on down the line until
you have all five hinges started. Then you can finish pushing the
aileron up against the back of the wing. Don't be overly concerned
if the hinges don't end up perfectly straight or perfectly centered in
the slots - approximately halfway is good enough. AGAIN, DO
NOT GLUE THE HINGES IN AT THIS TIME!
❑ 3) To set the proper amount of gap between the aileron and the
wing, simply deflect the aileron to the maximum amount of travel
needed. This will automatically set the proper hinge gap! Keep in
mind that for best control response the gap should be kept as
small as possible, but big enough to allow full movement of the
control surface. Make sure everything is functioning properly
before proceeding to the next step.
❑ 4) Flex the aileron downward, exposing the hinges between
the wing and aileron. Carefully place 3-4 drops of Thin CA glue
directly onto each hinge in the gap. You will notice that the glue is
quickly wicked into the slot as it penetrates both the wood and the
hinge. Turn the part over and apply 3-4 drops of glue to the other
side of each hinge. Keep a rag handy to wipe off any excess glue.
Note: We recommend using a fine-tip applicator on your CA glue
bottle. If you happen to get glue smears on the plastic covering,
don't worry about them right now. Once the glue is dry, you can
clean the glue smears off the covering with CA Debonder.
❑ 5) Allow at least 10 minutes before flexing the aileron. After
sufficient time has passed, flex the aileron up and down several
times. At first you might notice a little stiffness in the joint. This will
go away after the hinges have been flexed back and forth a few
times. Also, pull on the aileron at each hinge location to make sure
all the hinges are securely in place. Repeat this process to attach
the other aileron to the other wing.
WARNING: The CA hinges provided in this kit are made of a
special absorbant material that can only be glued with Thin CA
adhesive. Thin CA (any brand) is the ONLY type of glue that can
be used on these hinges - do not use epoxy or any other type of
glue! Also, never use CA Accelerator on CA Hinges!
It's critical that you only make one application of glue to each side
of a CA Hinge! If you apply additional glue after the first application
of glue is dry, the second application of glue will merely puddle in
the hinge gap and make the hinge too stiff to operate. The excess
glue could also weaken the hinge! When properly glued, the part of
the hinge that you can see in the hinge gap should have a dry
appearance, not wet. A dry appearance indicates that almost all of
the glue has properly soaked into the hinge slot. A wet appearance
indicates that excess glue is puddled in the hinge gap. Three to four
drops of Thin CA is the right amount
.
WING ASSEMBLY, PART IV: Install Control Horns & Pushrods
For the following steps you will need these parts:
• The wing assembly
• 2 - Nylon Control Horns & Retainer Plates
• 4 - M2 x 15mm Phillips-Head Bolts
• 2 - Wire Aileron Pushrods
• 2 - Metal R/C Links
❑ 1) Use a straight edge and a fine line marker to draw a guideline
on the aileron which lines up with the last hole in the aileron servo
output arm. This line should be 90Oto the hinge line of the aileron.
❑ 2) Set a Nylon Control Horn in place on the bottom of the
aileron. The front edge of the horn's base should be located at the
front edge of the aileron leading edge bevel. The upright arm of

WING ASSEMBLY, PART V: Fitting the Wing to the Fuselage
For the following steps you will need these parts:
• The wing assembly
• 1 - Fuselage
• 1 - Plywood Wing Bolt Plate
• 2 - 1/4-20 x 1-1/2" Nylon Wing Bolts
• 2 - Fiberglass Wing Bolt Guides
• 1 - Fuselage Bottom Fairing
❑ 1) Trial fit the wing in place on the fuselage, using the two
1/4-20 x 1-1/2" Nylon Wing Bolts provided. The nylon wing bolts
should pass freely thru the holes near the trailing edge of the wing
and thread into the blind nuts that are pre-installed in the fuselage.
Do not overtighten the bolts - just snug them up enough to hold the
wing in place for the next step.
Note: If you have any difficulty mounting the wing to the fuselage,
find the cause of any binding now, and fix it before proceeding.
❑ 2) Set the Fuselage Bottom Fairing in place on the bottom of the
wing. Align it with the fuselage. Use a felt-tip pen to mark the
location of the bottom fairing on the wing surface. Mark both sides.
Then remove the fairing and the wing from the fuselage.
❑ 3) Remove the covering material from the bottom of the wing
between the marked lines. Start by using a sharp hobby knife to
cut through the covering material along the marked lines. Be very
careful to cut the covering material only - not the balsa wood
structure underneath! Once you've cut through the covering
material, peel the unwanted covering off the wing.
the control horn should be lined up with the line you drew in the
previous step. Once you have the horn properly located, mark the
location of the two control horn mounting holes onto the aileron.
Drill a 1/16" dia. hole completely through the aileron at each mark.
❑ 3) Mount the control horn in place using the Nylon Retainer
Plate on the top side of the aileron and two M2 x 15mm Phillips-
Head Bolts.
❑ 4) Repeat the last three steps to mount a control horn on the
other aileron.
❑ 5) Note that the Wire Aileron pushrods have threads and an
adjustable R/C Link on one end, and a pre-formed "z-bend" on the
other end.
a) Install the z-bend end of the pushrod into the outer hole of
the aileron servo output arm. Note: The hole in the servo output
arm may be a little too tight. If necessary, drill out the holes in the
arm with a 5/64" dia. or #50 (.070") drill bit.
b) Install the servo arm and pushrod onto the servo, making
sure it is accurately centered in neutral position.
c) Clip the R/C Link into the control horn. Check the aileron for
neutral position, adjusting the overall length of the pushrod by
screwing the R/C Link in or out as needed to get the aileron in
neutral position when the servo is in neutral position.
Note: Because of the thickness of the MAYHEM airfoil, it is not
easy to determine exactly when the aileron is in neutral position.
For this reason we have supplied an Aileron Positioning Guide
(APG). Cut out the APG and use it to hold the aileron in true
neutral position when making your pushrod length adjustments.
SAFETY NOTE: Cut and fit a short length (about 3/16" or so) of
medium diameter fuel tubing (not furnished) onto the R/C Link to
prevent it from opening and coming off the control horn in flight.
6

FUSELAGE ASSEMBLY, PART I: Engine Mounting
For the following steps you will need these parts:
• 1 - Fuselage
• 2 - Glass-Filled Engine Mounts
• 4 - M3 x 20mm PH Bolts
• 4 - M3 Flat Metal Washers
• 4 - M3 Split Lock Washers
• 1 - Engine and suitable engine mounting Bolts (not supplied)
❑ 1) Bolt the Engine Mounts in place on the front of the firewall
using the M3 x 20mm Phillips-Head Bolts, Flat MetalWashers, and
Split Lock Washers provided.
❑ 2)The 1-5/8" vertical spacing between the mounting bolts, along
with the slotted holes in the engine mounts, allow the engine
mounts to accomodate any engine that has a crankcase width
between 1-1/8" to 1-9/16". That should cover any engines within
the recommended size range for the Mayhem 40.
❑ 3) a. Move your engine forward or backward on the engine
mounts until you measure exactly 4-5/8" from the front face of the
prop drive washer to the front of the firewall. This is the distance
your engine needs to be from the firewall for proper cowl
7
❑ 4) Glue the Plywood Wing Bolt Plate in place on the bottom of
the wing, carefully aligning the two 1/4" holes in the plate with the
holes in the wing before the glue dries. Make sure there is no
excess glue inside the holes. If necessary, run a 1/4" dia. drill bit
through the holes after the glue is completely dry.
❑ 5) Now permanently glue the Fuselage Bottom Fairing onto the
bottom of the wing with thick CA or epoxy glue. Let dry.
❑ 6) a.Bolt the wing back in place on the fuselage. Locate the two
Fiberglass Wing Bolt Guides and fit them into the wing bolt holes
in the bottom fairing. The guides should slip into the holes and go
all the way down against the surface of the wing and around the
head of the wing bolt.
b. Once you have the wing bolt guides fitted in place, use a
little thin CA glue to adhere them to the bottom fairing. Let dry.
c. Use a sharp hobby knife to trim the excess wing bolt guide
off flush with the bottom fairing. Don't try to take it all off with one
deep cut - cut off small pieces at a time. By working slowly and
carefully, you can get it trimmed off without gouging or cutting into
the bottom fairing.
d. With the wing removed from the fuselage, and the wing
bolts removed from the wing, put a few drops of thin CA glue in the
bottom of the wing bolt guides to bond them to the surface of the
wing. Don't use too much.

❑ 1) a. Insert one of the M4 x 34mm PWA Axle Bolts through the
hub of one of the 2-1/4" dia. Main Wheels. Slide the wheel all the
way up against the head of the bolt.
b. Next thread a M4 Lock Nut onto the threaded end of the
bolt, and run it all the way up to the wheel - but not too tight - the
wheel must turn freely.
c. Now thread a M4 Hex Nut up tight against the Lock Nut.
This hex nut serves as a spacer to keep the tire from rubbing on
the wheel pant after it is installed.
d. Finally, insert the threaded end of the axel bolt through the
aluminum landing gear leg and install another M4 Lock Nut on the
inside of the landing gear leg. Tighten securely.
e. Repeat this proceedure to install the other wheel onto the
opposite landing gear leg.
❑ 2) Mount the Fiberglass Wheel Pants to the landing gear with
the M3 x 10mm PWA Bolts and M3 Split Lock Washers provided.
Tighten securely. Double check to make sure that the wheels turn
freely without obstruction.
❑ 3) Bolt the main landing gear assembly onto the bottom of the
fuselage using the M4 x 15mm PWA Bolts and M4 Split Lock
Washers provided. Put a drop of thread locking compound, such
as Locktite®, on the threads of the bolts before screwing them in.
alignment and prop clearance purposes. Accurately mark the
engine's mounting bolt hole locations onto the engine mounts.
Then set the engine aside.
b. Drill the four engine mounting holes completely through the
mounts. Be very careful to drill them perpendicular to the mount.
Use a drill press if available.
c. Mount your engine in place on the engine mounts. We
suggest using a little thread locking compound (Loctite®) on the
mounting bolts to keep them from coming loose.
Note: This kit DOES NOT contain bolts for mounting your engine
to the engine mounts. That's because not all of the engines that
can be used in the Mayhem use the same size bolts. Some
engines may need 4-40 size bolts, while others may need 6-32.
You will need to go to the hobby shop to obtain the correct size
mounting bolts for your engine..
FUSELAGE ASSEMBLY, PART II: Main Landing Gear
For the following steps you will need these parts:
• The fuselage assembly
• 1 - Aluminum Landing Gear
• 2 - M4 x 15mm PWA Bolts
• 2 - M4 Split Lock Washers
• 2 - 2-1/4" dia. Main Wheels
• 2 - M4 x 34mm PWA Axle Bolts
• 4 - M4 Lock Nuts
• 2 - M4 Hex Nuts
• 1 - Right Fiberglass Wheel Pant
• 1 - Left Fiberglass Wheel Pant
• 4 - M3 x 10mm PWA Bolts
• 4 - M3 Split Lock Washers
Note: When assembling the hardware in the following steps, we
recommend that you use a thread-locking compound, such as
Locktite®, to keep the parts from vibrating loose in flight. It only
takes a small drop, placed right in the threads of the mating parts,
to keep them tight and secure. 8
IMPORTANT SAFETY ISSUE!
DO NOT DRILL AND TAP THE GLASS-FILLED ENGINE MOUNTS
FOR BOLTS, OR USE SELF-TAPPING SCREWS OR WOOD
SCREWS. THOSE METHODS WILL WEAKEN THE ENGINE
MOUNTS AND CAN LEAD TO ENGINE MOUNT FAILURE!
1) Use only Socket-Head Bolts with Aircraft Lock Nuts and Flat
Metal Washers to fasten your engine to the glass-filled engine
mounts, as shown in these instructions.
2) The holes you drill through the mounts must be big enough for the
engine mounting bolts to pass freely through. The bolts should not go
in tight. In the case of 4-40 mounting bolts, a 1/8" dia. drill bit will
provide proper clearance holes. For 6-32 bolts use a 5/32” drill bit.

FUSELAGE ASSEMBLY, PART III: Cowling and Spinner
For the following steps you will need these parts:
• The fuselage assembly
• 1 - Fiberglass Cowling
• 5 - M2.6 x 8mm PWA Screws
• 1 - 2-1/4" Plastic Spinner Assembly
❑ 1) Try fitting the Fiberglass Cowling over your engine and back
onto the fuselage. If you have a typical MAYHEM engine
installation (meaning a single-cylinder engine mounted inverted)
you will need to make an opening in the bottom of the cowling for
the engine cylinder to stick through. Watch carefully to see where
the head of the engine first hits the inside of the cowling and mark
that location with a pencil or felt tip marker. Remove the cowl, and
use a Dremel®Tool to make a small opening in the cowl at the point
of contact. Refit the cowl, checking the hole location and size,
adjust as needed and again use the Dremel®Tool to make the
opening bigger. Keep refitting, remarking and readjusting the hole
until the cowling can be slipped over the engine into correct
position on the fuselage. As a general rule, you should end up with
at least 3/16" clearance between the cowling and any engine part.
❑ 2) Once the cowling is in place without any part of the engine
contacting it, mount your spinner backplate and propeller on the
engine prop shaft. Tighten the prop assembly sufficiently to bring
the spinner backplate firmly in contact against the engine's prop
mounting flange. Now check to see that you have at least a 1/16"
gap between the back of the spinner backplate and the front of the
cowling (1/16" to 1/8" is OK). Adjust the final location of the
cowling, making sure that the spinner backplate is centered on the
front and that the back edges are tight against the fuselage. Use
masking tape to temporarily hold the cowling in correct position on
the fuselage.
❑ 3) With the cowling securely taped in place, use a 3/64" (or #56)
dia. drill bit to drill pilot holes in the fuselage, centered in each of
the four pre-drilled mounting holes in the cowl. Mount the cowl to
the fuselage with the four M2.6 x 8mm PWA Screws provided.
❑ 4) Determine what size and shape opening you will need in the
cowling to accomodate your engine's muffler. Then cut the
opening in the cowling, starting small and gradually opening it up
to the final size.
Note: As you can see in the next photo, the cutout for the YS-63
muffler in our photo model was a fairly simple 5/8" wide slot cut
straight forward from the back edge of the cowl. The slot is
approximately 2-1/4" long. We used an additional M2.6 x 8mm
PWA Screw (provided) to hold down the corner of the cowling just
above the slot. Depending upon your exact engine ocnfiguration,
you may do something similar for your Mayhem.
❑ 5) Determine the location of the hole required in the cowling for
access to your engine's needle valve. Start with the engine and
cowling on the airplane and "eyeball" the approximate location of
where the needle valve will exit the cowling. Take your best guess
and mark that location on the cowl. Now make a small 1/16" dia.
hole at the marked location. Chances are that you are close to the
correct spot. Stick a piece of music wire into the hole, down to the
needle valve. Carefully observe if the hole needs to be
repositioned to straighten up the wire, as if it were the needle
valve. Make another mark on the cowl and open the hole just a
little towards the corrected position. In this manner, continue
checking and adjusting the exit hole until it aligns perfectly with the
carburetor/needle valve position. Then enlarge the hole enough to
insert and install the needle valve in the carb. Be sure the hole has
at least 3/32" clearance around the needle valve to avoid contact.
Tip: A handy tool to assit with cutting holes in the cowling is a
small penlight. The penlight can be used from the inside or
outside of the cowl to highlight and spot the required hole location.
❑ 6) Figure out how you are going to light your glow plug and
whether that will require an additional opening in your cowling.
Note: For the YS-63, we did not need an additional opening - the
glow plug is accessible through the opening we made in the
bottom of the cowling.
9

❑ 3) Mount the wing to the fuselage, and then trial fit the
stabilizer/elevator assembly in place. Check the alignment of the
stab with the rest of the airplane. View the airplane from the top,
front and rear, making sure the stabilizer is not tilted or skewed
(see drawing on next page). Measure the distance from the wing
trailing edge back to the stab's leading edge tip, and note the
distance. Then make the same measurement on the opposite side
of the airplane. The two measurements must be the same. Adjust
the stabilizer as needed until they are the same.
❑ 4) The stabilizer/elevator assembly can now be permanently
glued into the fuselage. Slow-drying epoxy glue is recommended
for this step, to allow you plenty of time to get the stab back in
proper alignment before the glue dries. Wipe any epoxy glue
smears off the covering material with a rag soaked in rubbing
alcohol.
❑ 5) Seperate the Fin and Rudder from each other, and set the
Rudder and Hinges aside for now. Trial fit the fin alone in place on
the fuselage. There should be no gaps between the bottom of the
fin and the top of the fuselage. If there are any gaps, sand the
bottom of the fin to eliminate them.
❑ 6) Use a felt-tip pen to mark the locaton of the fin on the top of
the fuselage. Then take the fin back off the airplane and remove
the covering material from the top of the fuselage between the
marked lines, (see photo on next page). This must be done to
provide a strong wood-to-wood joint between the bottom of the fin
and the fuselage.
❑ 7) Next figure out how you are going to fuel and de-fuel your
airplane, and whether that will require another opening in your
cowling. If so, make the appropriate opening at this time.
Note: For the YS-63, we did not need an additional opening - the
fueling is done through the opening we made for the cylinder head
in the bottom of the cowling.
❑ 8) The supplied plastic Spinner is easy to assemble. If the
diameter of your engine's prop shaft is smaller than the hole in the
spinner backplate, select a prop shaft adapter to fit. If your prop
shaft is larger than the hole in the backplate, the hole can be drilled
larger to fit (use drill press). Install the backplate and your
propeller tightly onto your engine, using the engine's prop nut and
washer. Snap the spinner cone in place, and attach it to the
backplate with the four screws provided. Don't over-tighten the
screws.
FUSELAGE ASSEMBLY, PART IV: Tail Surfaces &Tailwheel
For the following steps you will need these parts:
• The fuselage assembly
• 1 - Stabilizer & Elevator Set
• 1 - Fin & Rudder Set
• 9 - CA Hinges (6 for elevators, 3 for rudder)
• 1 - Tailwheel Wire, Mounting Bracket, Wheel Collar, Set Screw
• 4 - M2 x 10mm Phillips-Head Screws
• 1 - 1" dia.Tail Wheel
• 1 - Wheel Collar w/ Set Screw
❑ 1) Six CA hinges have been factory installed, but not glued, in
the Stabilizer and Elevator set. Glue the hinges permanently in
place at this time, using the same proceedures used for gluing the
aileron hinges on page 5. Let dry 10 minutes before flexing the
hinges. Do not glue the Fin and Rudder hinges at this time!
❑ 2) Prepare the fuselage to receive the stabilizer and elevators by
extending the stabilizer cutout all the way to the back of the
fuselage. In other words, cut out the portion of the fuselage that is
directly behind the stabilizer slot, so that the stab and elevators
can then be slid in place from the back. This portion of the
fuselage was left in during manufacture of the airplane to lend
support the top of the fuselage during shipping and handling.
10
b. Use a hobby razor saw
and/or hobby knife to cut out the
unwanted portion of wood
between the lines.
c. Smooth the surfaces of the
fresh cuts with fine sandpaper,
and then fuel proof the exposed
wood with some thin CA glue.
a. Start by drawing guidelines
on the rear of the fuselage to
indicate exactly where cuts
should be made to remove the
unwanted portion. The guidelines
are simply a straight extension of
the top and bottom edges of the
stabilizer slot.

❑ 10) Hold the plastic tailwheel Mounting Bracket in place against
the bottom of the fuselage. Mark the locations of the four
mounting holes on the fuselage. Drill 3/64" dia. pilot holes at the
marks. Install the Mounting Bracket with the four M2 x 10mm
Phillips-Head Screws provided.
❑ 11) Hold the Wheel Collar that is on the Tailwheel Wire up tight
against the bottom of the Mounting Bracket, and then tighten the
Set Screw.
❑ 12) Install the 1" dia. Tail Wheel on the axle, holding it in place
with the Wheel Collar provided.
RADIO INSTALLATION, PART I: Elevator
For the following steps you will need these parts:
• The fuselage assembly
• 1 - Nylon Control Horn and Retainer Plate
• 2 - M2 x 15mm Phillips-Head Bolts
• 1 - Wire Elevator Pushrod
• 1 - Metal R/C Link
• 1 - Elevator Servo (not supplied)
• 1 - 12" Servo Extension Chord (not supplied)
❑ 1) Plug a 12" long servo extension chord onto the end of the
elevator servo wire. Secure well with tape. Poke the free end of
the extended servo wire through the elevator servo mount in the
rear of the fuselage. Hold the fuselage vertically, nose down,
as you pass the servo wire all the way forward to the radio
compartment. Once you have the wire completely inside, install
the elevator servo in the fuselage using the using the rubber
grommets and screws that came with the servo.
❑ 2) Mount a control horn on the BOTTOM OF THE LEFT
ELEVATOR. Locate the horn at the inboard end of the elevator,
directly in line with the elevator servo. The front edge of the horn's
base should be located right at the front edge of the elevator's
leading edge bevel. Once you have the horn properly located,
❑ 7) The fin can now be permanently glued in place on the
fuselage. Epoxy glue is recommended for this step for maximum
strength. Wipe any excess epoxy glue smears off the covering
material with a rag soaked in rubbing alcohol.
❑ 8) Look closely at the bottom of the rudder leading edge. Notice
that there is a pre-drilled hole in the leading edge, about 5/8" up
from the bottom corner, where the 90Oarm of the Tailwheel Wire
will be installed.
c. Glue the Tailwheel Wire in place, being careful not to get any
glue on the plastic Mounting Bracket.
❑ 9) Install the rudder to the back of the fin and fuselage with three
CA Hinges. After preliminary assembly and alignment, glue the
hinges permanently in place using the same proceedures you
used for gluing the aileron hinges and elevator hinges in previous
steps. Let dry 10 minutes before flexing the hinges.
11
a. Use a sharp #11 hobby knife
or single-edge razor blade to inlet
the rudder leading edge, from the
hole down to the bottom corner, to
accept the shank of the Tailwheel
Wire.
b. Trial fit the Tailwheel Wire in
place in the rudder leading edge.
Adjust the slot if necessary.

Once you have the horn properly located, mark the location of the
two control horn mounting holes onto the rudder. Drill a 1/16" dia.
hole completely through the rudder at each mark. Mount the
control horn in place with the Nylon Retainer Plate and two
M2 x 15mm Phillips-Head Bolts.
❑ 3) The rudder pushrod consists of a wire rod with threads and
an adjustable R/C Link on one end, and a pre-formed "z-bend" on
the other end.
a) Install the z-bend end of the pushrod into the outer hole of
the rudder servo output arm. Note: The hole in the servo output
arm may be a little too tight. If necessary, drill out the holes in the
arm with a 5/64" dia. or #50 (.070") drill bit.
b) Install the servo arm and pushrod onto the servo, making
sure it is accurately centered in neutral position.
c) Clip the R/C Link into the control horn. Check the rudder
for neutral position, adjusting the overall length of the pushrod by
screwing the R/C Link in or out as needed to get the rudder in
neutral position when the servo is in neutral position.
SAFETY NOTE: Cut and fit a short length (about 3/16" or so) of
fuel tubing (not furnished) onto the R/C Link to prevent it from
opening and coming off the control horn in flight.
RADIO INSTALLATION, PART III: Throttle Pushrod
For the following steps you will need these parts:
• The fuselage assembly
• 1 - 1/8" od x 12-1/2" Plastic Pushrod Tube
• 1 - 3/16" od x 11-3/8" Plastic Pushrod Sleeve
• 2 - M2 x 7/8" long Threaded Studs
• 2 - Metal R/C Links
• 1 - Plywood Pushrod Support
• 1 - Throttle Servo (not supplied)
The following instructions describe installation of the throttle
pushrod components that are included in this kit with the YS-63
engine that we used. This pushrod system should be adaptable to
most 4-stroke or 2-stroke single cylinder glow engines. There may
be some engine installations that require a slightly different
pushrod arrangement and additional materials (not supplied).
Take a few minutes to study your engine installation and develope
a plan on how you can best route your throttle pushrod from the
engine, through the firewall, around the fuel tank, and back to the
throttle servo.
❑ 1) Drill a 3/16"-7/32" dia. hole through the firewall, aligned with
the engine's carburetor throttle arm. From the front, insert the
3/16" od x 11-3/8" long Plastic Pushrod Sleeve through the firewall
12
mark the location of the two control horn mounting holes onto the
elevator. Drill a 1/16" dia. hole completely through the elevator at
each mark.Mount the control horn in place with the Nylon Retainer
Plate on the top side of the elevator and two M2 x 15mm Phillips-
Head Bolts.
❑ 3) The elevator pushrod consists of a wire rod with threads and
an adjustable R/C Link on one end, and a pre-formed "z-bend" on
the other end.
a) Install the z-bend end of the pushrod into the outer hole of
the elevator servo output arm. Note: The hole in the servo output
arm may be a little too tight. If necessary, drill out the holes in the
arm with a 5/64" dia. or #50 (.070") drill bit.
b) Install the servo arm and pushrod onto the servo, making
sure it is accurately centered in neutral position.
c) Clip the R/C Link into the control horn. Check the elevator
for neutral position, adjusting the overall length of the pushrod by
screwing the R/C Link in or out as needed to get the elevator in
neutral position when the servo is in neutral position.
SAFETY NOTE: Cut and fit a short length (about 3/16" or so) of
medium diameter fuel tubing (not furnished) onto the R/C Link to
prevent it from opening and coming off the control horn in flight.
RADIO INSTALLATION, PART II: Rudder
For the following steps you will need these parts:
• The fuselage assembly
• 1 - Nylon Control Horn and Retainer Plate
• 2 - M2 x 15mm Phillips-Head Bolts
• 1 - Wire Rudder Pushrod
• 1 - Metal R/C Link
• 1 - Rudder Servo (not supplied)
• 1 - 12" Servo Extension Chord (not supplied)
❑ 1) Plug a 12" long servo extension chord onto the end of the
rudder servo wire. Secure well with tape. Poke the free end of the
extended servo wire through the rudder servo mount in the rear of
the fuselage. Hold the fuselage vertically, nose down, as you pass
the servo wire all the way forward to the radio compartment. Once
you have the wire completely inside, install the rudder servo in the
fuselage using the using the rubber grommets and screws that
came with the servo.
❑ 2) Mount a control horn on the RIGHT SIDE OF THE RUDDER.
Locate the horn directly in line with the outermost hole of the
rudder servo arm. The front edge of the horn's base should be
located right at the front edge of the rudder's leading edge bevel.

13
and operate the throttle pushrod tube from the servo end. Make
sure the pushrod can fully open and close the carburetor without
binding.
❑ 7) Finish the servo end of the throttle pushrod as follows:
a. Turn your radio on and make sure the throttle servo is
operating in the right direction for high and low throttle. Put the
throttle servo in high throttle position and turn off the radio.
b. Put the throttle pushrod in high throttle position.
c. Inside the fuselage, clip the Threaded Stud with Metal R/C
Link to the servo arm. Hold the threaded stud and the pushrod
tube alongside each other and mark the tube for cutting to length.
Remember to allow for the 1/8" that the threaded stud will be
screwed inside the end of the pushrod tube. Once you’ve
determined the correct length, cut off the excess pushrod tube with
a sharp razor knife.
d. Unclip the R/C link from the servo arm and screw the
threaded stud 1/8" inside the end of the pushrod tube, as you did
the other end in step 5. Then reattach the R/C link to the servo
arm. Use a small piece of fuel tubing (not supplied) on the R/C link
to keep it from coming open.
❑ 8) Turn your radio back on and check the operation of the
throttle. Adjust the overall length of the throttle pushrod by scewing
the R/C links in or out as needed to achieve full throttle control.
When finished, secure at least one of the R/C links to it's threaded
stud with CA glue, so that the pushrod tube cannot rotate in flight
and change adjustment.
RADIO INSTALLATION, PART IV: Radio System
With all the servos now installed, all that remains is the installation
of the receiver, battery pack and switch.
RX BATTERY PACK: The single heaviest unit of the radio system
is the battery pack. This means that you can, if needed, locate the
battery pack wherever it is needed in the airplane to help achieve
the correct balance point. Be sure to wrap the battery pack in foam
rubber to isolate it from vibration. Use more foam packing, rubber
bands or tie-wraps to secure it to the model structure so that it
can't move around in flight.
RECEIVER: Wrap the receiver in foam and secure it in the
fuselage. Route the receiver antenna outside the model and
secure it back near the tail of the airplane.
Notes about our installation: To achieve proper balance with the
YS-63 in our prototype, we needed to put both the battery pack
and the receiver in the area just in front of the servo tray. So we
wrapped the battery pack and the receiver together in a single
piece of foam rubber, with a seperate piece of foam rubber
between them, as shown in the next photo.
For the receiver antenna, we drilled a 1/16” dia. exit hole in the
right fuselage side at the receiver position. The antenna goes
through the hole and is string back to the tail of the airplane. We
and back into the fuselage. Notice that there is a slot cut in the first
fuselage former behind the firewall for the pushrod sleeve to go
through. This slot keeps the pushrod sleeve out of the area where
the fuel tank is mounted.
❑ 2) After you get the pushrod sleeve through the slotted former in
the tank area, experiment with different routings of the pushrod
from that point back to the area where the throttle servo will be
located. Once you've decided on the best location for your throttle
servo and route for your pushrod, mount the throttle servo in the
plywood servo tray using the rubber grommets and mounting
screws that came with the servo.
Note: In our installation of the YS-63, we mounted the throttle
servo near the fuselage side (look ahead to next 2 photos to see
our finished throttle pushrod installation). We made a small notch
in the fuselage former that is located at the leading edge of the
wing opening to accomodate the pushrod. It’s a straight shot from
there back to the servo arm.
❑ 3) Inside the fuselage, slip the Plywood Throttle Pushrod
Support over the end of the pushrod sleeve. The plywood pushrod
support should be positioned near the end of the throttle pushrod
sleeve. Its job is to aim the end of the pushrod directly at the
throttle servo arm. Feel free to change the overall length of the
pushrod support if necessary to fit your particular installation.
Once you've determined where to mount it, glue the plywood
pushrod support to the fuselage structure.
❑ 4) Determine how long the pushrod sleeve needs to be to fit your
installation (we purposely provided it too long so it would work with
practically any installation). In most cases you will need to
shorten the pushrod sleeve a little bit. As a general rule, the ends
of the pushrod sleeve should be about 1-1/2" away from the servo
arm and the throttle arm. Use a sharp razor blade to cut the
pushrod sleeve to length. Remove the tube and sand its surface
with 220 sandpaper to rough it a little. Reinstall the tube and glue
it in place to the firewall and the plywood pushrod supports.
❑ 5) Screw the Threaded Stud with R/C Link into one end of the
1/8" od x 12-1/2" Plastic Pushrod Tube. Use a needle nose pliers
to grip the threaded stud so you can screw it in at least 1/8".
❑ 6) At the firewall, insert the plain end of the plastic pushrod tube
inside the plastic pushrod sleeve. Push it in until the R/C link can
be clipped to engine throttle arm. Then reach inside the fuselage

model and still have solid control. Have an assistant stand by the
airplane to watch the action of the control surfaces, while you walk
slowly away from the model, constantly working the controls as
you go. Your assistant should signal to you if the control surfaces
become erratic. If all is well out to 100 ft.or further, repeat the test
with the engine running, with the assistant holding the airplane. If
the control surfaces do not respond correctly, do not fly! Find and
correct the problem first. Look for loose servo connections or
broken wires, corroded wires, poor solder joints in your battery
pack, or a defective cell in the battery pack, or a damaged
receiver crystal from a previous crash. If you can't find and fix the
problem, send the radio in to an approved service center.
NEVER FLY WITH A RADIO SYSTEM THAT ISN'T WORKING
100% CORRECTLY. THE PROBLEM WON'T GET BETTER IN
THE AIR, IT WILL GET WORSE!
RADIO INSTALLATION, PART VI: Set The Control Throws
Use a ruler to accurately measure and adjust the travel of each
control surface to the amounts shown below. Keep in mind that
these settings are meant to serve as a starting point. As you gain
experience flying your MAYHEM, you may want to adjust the
throws to suit your flying style. All measurements should be taken
at the widest part of the elevators, ailerons, and rudder.
Low Rate High 3D Rate
Ailerons 1" up 2" up
1" down 2" down
-20% expo -70% expo
Elevator 1" up 2" up
1" down 2" down
-20% expo -50% expo
Rudder 2" right 3"-4" right
2" left 3"-4" left
-20% expo -70% expo
Note: High Rate 3D ControlThrows
The 3D control throws are only meant for extreme aerobatics.
They are not meant for normal flying. You should be competent
and comfortable flying your MAYHEM with normal control throws
before attempting 3D rates.
FUEL TANK INSTALLATION
❑ 1) Assemble the fuel tank as shown. We recommend that you
plumb your tank with a standard 2 tube setup. One of the tubes is
the "vent" line, through which you will fuel and defuel the tank. The
other tube is the "fuel feed" line to the carburetor.
Note that the rubber stopper for the tank has two holes that go all
the way through it. Use these holes for the aluminum vent and fuel
feed tubes. Use the shortest of the three supplied aluminum tubes
secured the end of the antenna under the stabilizer, using a piece
of small fuel tubing, a small rubber band, and the head of the “T-
pin” glued into the fudselage side, as shown in the second photo.
SWITCH: The radio on/off switch should be mounted on the
fuselage side opposite the engine exhaust. Cut a small
rectangular opening in the fuselage side for the switch toggle to
poke through, and drill two small holes for the switch mounting
bolts.
RADIO INSTALLATION, PART V: Final Safety Inspection
1) Take the time to fit each R/C link with a short length of silicone
fuel tubing to keep the links firmly closed. This common safety
practice has saved a lot of models!
2) Make sure that you have secured the servo arms to each servo
with the retaining screws.
3) Turn the radio on and check the functions of all the controls.
Make sure they are moving in the right direction! Thousands of
R/C airplanes have crashed over the years because the servos
were moving the wrong way! Also make sure all the servos are
centered and working perfectly, without any binding. Correct any
such problems now, before proceeding.
4) Be sure to range check your radio installation on the ground,
before you attempt to fly your MAYHEM for the first time. With the
transmitter antenna collapsed, and the receiver and transmitter
turned on, you should be able to walk at least 100 ft.away from the14

DECAL APPLICATION
The decals in this kit are made of sticky-back mylar with an
extremely aggressive adhesive. They are NOT water activated
transfers. These decals are not die-cut and need to be cut from
their sheets with a sharp hobby knife or scissors. Trim as close to
the image as possible.
Putting sticky-back decals on a model can be tricky! Especially
medium to large size ones like those in this kit. If you don't do it
right you will end up with unsightly air bubbles trapped underneath
the decal. The best method is to put large decals on "wet".
You will need a "soapy water" mixture (water mixed with a very
small amount of dish soap, or SIG Pure Magic Model Airplane
Cleaner, or Fantastic®, Windex®, or 409®type cleaners all work
good). You will also need a supple squeegee (the SIG 4" Epoxy
Spreader #SIGSH678 is perfect for this job), a couple clean soft
cloths (old tee shirts are great), a good straight edge, a ruler, and
a hobby knife with sharp #11 blades. We also suggest that you
have some trim tape handy for making temporary guidelines (1/8"
width or so is perfect) for help in aligning the decals.
First spray the surface of the model where the decal is to be placed
with a soapy water mixture. Then peel the backing sheet
completely off the decal, being careful not to let the sticky side
double over and adhere to itself. Place the decal onto the wet
surface of the model. Do not push down! The soapy water
solution will keep the decal from actually sticking to the model until
you have had time to shift it around into exact position. Once you
have it in position, squeegee the excess soapy water out from
under the decal. Mop up the water with a dry cloth. Squeegee
repeatedly to get as much of the water out from under the decal as
possible.
BALANCE THE MODEL
While all airplanes must be balanced to achieve flight, the balance
of an aerobatic airplane like the MAYHEM 40 is especially critical.
The final placement of the longitudinal Center of Gravity, or
Balance Point, will have a great effect on the aerobatic
performance of this airplane. Balancing this model should be
approached with patience and care.
for the fuel feed tube. Use the longest of the aluminum tubes for
the vent tube. Gently bend the vent tube upwards to 90O, so it will
be near the top of the tank. Adjust the length of the internal
silicone fuel tubing to allow free movement of the metal clunk
pick-up inside the tank. Install the stopper assembly into the neck
of the tank and secure by tightening the clamp bolt.
Be sure to label the "vent" and "carb" lines for later identification.
❑ 2) Trial fit the tank in place into the front of the fuselage to
familiarize yourself with how it mounts. The front of the tank should
fit through the hole in the firewall. The main body of the tank is
supported by the contoured hole in the fuselage former. Take the
tank back out of the fuselage.
❑ 3) Apply a bead of silicon adhesive around the neck of the tank,
where it will contact the inside of the firewall. Put another big blob
of silicone on the front of the tank just below the neck. Slide the
tank in place into the fuselage, pushing it in until the neck goes into
the hole in the firewall.
❑ 4) A 5/16" x 1/2" x 2-7/8" balsa stick is provided to keep the fuel
tank in place. Install the balsa stick across the back of the tank,
gluing it to the front of the fuselage former. This will keep the tank
from sliding backwards in flight. If the tank ever has to be removed
for service, you can break the balsa stick loose to get the tank out.
15

secured in this way, level the wings and then slowly let go. Ideally
the wings should stay level when you put them there. If one wing
panel drops lower, it means that it is heavier than the other panel.
When flying the model, this imbalance can cause the airplane to
"pull" to the heavy side, especially in loops and up line maneuvers.
To make the airplane track true, the light wing panel needs weight
added so it will balance level with the other panel. Add stick-on
weights or push finishing nails into the light wingtip to achieve
balance. Always make sure the weights cannot come loose.
INCIDENCE & THRUST ANGLES
The MAYHEM 40 was built at the factory with the following specs:
Wing Incidence: 0O
Stab Incidence: 0O
Engine - Side View 0Odown
Engine - Top View 2Oright
FLYING
If you have carefully followed this assembly manual, test flying your
MAYHEM 40 should be a lot of fun. Try to choose a calm day with
little or no wind for the first flight. Good conditions allow you to
better evaluate and more accurately adjust the trim requirements
for your airplane. As we've mentioned before, a good running,
reliable engine is a must for the ultimate success of your airplane.
Take the time to solve any engine problems before you try to fly.
Always make it part of your pre-flight routine to check each control
on the airplane, making sure the surfaces are moving in the
correct directions. Also check each control linkage to be sure they
are secure and that nothing is loose.
After starting and warming up the engine, taxi the MAYHEM out to
the take-off position on the flying field. Hold up elevator during the
taxi to keep the tailwheel firmly to the ground. For take-off, the
airplane should be lined-up with the center of the field with the
nose pointed directly into the wind. Hold a little up elevator and
smoothly advance the throttle - do not slam the throttle full open all
at once. The airplane should roll forward smoothly, tailwheel on
the ground. As speed builds, back off of the up elevator input and
use the rudder as needed to maintain a straight takeoff run. The
tail will come up as flying speed is reached and a little up elevator
will lift the MAYHEM off the ground.
Maintain a straight outbound flight path, climbing at a shallow angle
until a safe maneuvering altitude is reached. Make your control
inputs smooth and avoid jerking the sticks. Once you achieve a
safe altitude, throttle back slightly to a nice "cruising" speed .
THROTTLE MANAGEMENT: The MAYHEM, and similar designs,
are not designed to fly at high air speeds. The key to their unique
flying characteristics is super light weight construction and extra
large control surfaces. Full throttle is only for takeoff and aerobatic
maneuvers. For normal level flight, you should throttle back to
cruising speed. Also, never dive the MAYHEM at full throttle (see
CAUTION note about control surface flutter at end of this page).
Once you've settled at cruising altitude and speed, adjust the trims
as needed to achieve hands off straight and level flight. Take it
easy with the MAYHEM for the first flight, gradually getting
acquainted with it as you gain confidence. Take the MAYHEM to a
safe altitude and throttle the engine back to idle. This will give you
a good idea of the glide characteristics. While still at idle, steadily
increase up elevator to get a feel for the stall characteristics. Stalls
tend to be very gentle with the nose dropping straight ahead with
little tendency to drop a wing. This is great information to have
when set up for your first landing.
16
Balance the MAYHEM with everything on board, including the
propeller, spinner, etc. Do not leave anything off the airplane that
will be on it during flight. DO NOT fill the fuel tank - the tank must
be empty during balancing!
BALANCE POINTS REFERENCE CHART
* Percentage of Mean Aerodynamic Chord
% of distance aft of
MAC* wing leading edge
29% 4.06"
31% 4.34"
33% 4.62"
34% 4.76"
35% 4.90"
36% 5.04"
37% 5.18"
38% 5.32"
For initial test flying and familiarization purposes, we suggest a
starting balance point of 33% MAC, which is approximately 4-5/6"
behind the leading edge of the wing.
IMPORTANT NOTE: Balanced means the airplane sets perfectly
level when supported at the desired balance point - NOT slightly
nose down or nose up - PERFECTLY FLAT LEVEL!
As your experience with the MAYHEM 40 increases, you can
adjust the balance point to suit yourself. In general, as the balance
point is moved aft, the airplane will become more responsive and
less stable in all axis. Some pilots like their models extremely
reactive, while others like to fly with more smoothness. If you
never get into 3D flying, you will probably like the balance point at
the intial setting of 33%. In the end, the final balance point and
control throws you use will depend on how you like to fly.
The best means of shifting the CG fore or aft is by shifting the
locatoin of the battery pack. If is the heaviest movable component
in the airplane. Wherever you put the battery pack, make sure it
cannot move around in flight. Our MAYHEM 40 prototypes required
no additional nose or tail weight to achieve different balance points.
We shifted the balance point by shifting the battery pack.
If moving your battery pack does not achieve the balance point you
want, and more weight is needed, consider using a larger (and
therefore heavier) battery pack. Try to avoid adding useless
weight. If you need more weight in the nose, try a heavier spinner
or replace the light wheels with heavier after-market wheels. If
your model is nose heavy and battery shifting does not work, you
can try adding lead stick-on weights in the rear of the fuselage.
After you've determined how much tail weight you need, the
weights can be placed inside the fuselage by simply removing the
elevator servo and placing the weights inside and securing them.
With the elevator servo back in place, the weights are hidden.
Lastly, the aerobatic performance of your MAYHEM 40 will benefit
greatly if you balance the airplane laterally as well as fore and aft
(eliminate the "heavy wingtip" syndrome). Lateral balancing
requires that the model be suspended upside down, using
substantial chord or fishing line. Hang the model in level flight
attitude from the ceiling or a rafter, with one line looped over the
engine propeller shaft and another line looped over the tailwheel
bracket. The model should hang level in side view. With the model
for
normal
flying
for
3D
flying

17
Landing the MAYHEM is typically a pleasure. To begin a landing
approach, lower the throttle partway while on the downwind leg.
This allows the nose of the model to drop slightly. Continue to
bleed off excess altitude, maintaining good airspeed and control,
while you make your final turn to the runway. Keep a little power
on the engine during final approach, down to a few feet off the
ground. The MAYHEM has a very thick wing and slows down
quickly when you completely close the throttle. Once the airplane
is 3-4 feet off the ground, close the throttle completely in
preparation for touchdown. Gradually add more up elevator as the
airplane slows down and settles towards the ground. Flair the
airplane as the ground approaches for a smooth 3-point landing
and rollout. Hard landings are not necessary - sound piloting skills
are. After landing, always remember to hold up elevator when
taxiing to keep the tailwheel firmly to the ground.
Before flying your MAYHEM 40 a second time, double check the
airplane for anything that may have come loose, become
disconnected, etc. during the first flight.
Each flight will be even more fun as you fine tune the trim of your
MAYHEM. Try a few loops and rolls. Inverted flight is easy,
requiring little down elevator for hold level flight. Next try some
snap rolls, spins, and knife edge flight. The MAYHEM should
perform all of these maneuvers with ease. Note any tendencies
that you can trim out when you're back on the ground. For
instance, if the MAYHEM has a tendancy to "pull", or drift, towards
the canopy during knife edge flight, try raising BOTH ailerons 1/2
turn. If it pulls towards the landing gear, lower both ailerons. Fly it
again and note any difference. Always make changes slowly, in
small amounts, and only one change per flight. As with any
aircraft, getting consistently good results from the MAYHEM is
usually a matter of flight trim and practice.
For those of you interested in 3-D aerobatics, set up your radio to
take advantage of the huge control movements available from this
model. However, we would urge you to "sneak up" on such
control throws, making very sure you have them available to you
only on your high rate switches!
CAUTION: If you notice any unusual sounds while flying, such as
a low pitched buzz, this may be control surface "flutter". Flutter can
happen to any R/C airplane. Designs like the MAYHEM 40, with
light weight, extra large control surfaces are especially vunerable.
Flutter can quickly destroy your aircraft if left unchecked. It can
break your pushrod linkages, strip gears inside the servo, and
even cause control surfaces or entire wings to come off the
airplane in flight. Anytime you detect flutter, you must
immediately cut the throttle and land the airplane! Check all servo
mountings and pushrod linkages before flying again. If a control
surface flutttered once, it will flutter again under similar
circumstances. In general, some of the things to look at when
trying to cure flutter are: Loose servo mounting screws or
deteriorated rubber grommets. Excessive hinge gap. Weak or
loose control horn. Weak or flexible pushrods. Poor fit of R/C link
pin in control horn. Internal servo gears that are weak, stripped, or
have excessive play or backlash.
Please operate your airplane in a safe, responsible manner with
constant regard to other flyers, spectators, and property.
GOOD LUCK AND GOOD FLYING!
WARNING! THIS IS NOT A TOY!
Flying machines of any form, either model-size or full-size, are not toys!
Because of the speeds that airplanes must achieve in order to fly, they are
capable of causing serious bodily harm and property damage if they crash.
IT IS YOUR RESPONSIBILITY AND YOURS ALONE to assemble this
model airplane correctly according to the plans and instructions, to ground
test the finished model before each flight to make sure it is completely
airworthy, and to always fly your model in a safe location and in a safe
manner. The first test flights should only be made by an experienced R/C
flyer, familiar with high performance R/C aircraft.
The governing body for radio-control model airplanes in the United States
is the ACADEMY OF MODEL AERONAUTICS, commonly called the AMA.
The AMA SAFETY CODE provides guidelines for the safe operation of R/C
model airplanes. While AMA membership is not necessarily mandatory, it
is required by most R/C flying clubs in the U.S. and provides you with
important liability insurance in case your R/C model should ever cause
serious property damage or personal injury to someone else.
For more information contact:
ACADEMY OF MODEL AERONAUTICS
5161 East Memorial Drive
Muncie, IN 47302
Telephone: [phone]
AMA WEB SITE: www.modelaircraft.org
CUSTOMER SERVICE
SIG MANUFACTURING COMPANY, INC. is committed to your success in
both assembling and flying the MAYHEM 40 ARF. Should you encounter
any problem building this kit, or discover any missing or damaged parts,
please feel free to contact us by mail or telephone.
SIG MANUFACTURING COMPANY, INC.
401-7 South Front Street
Montezuma, IA 50171-0520
SIG MODELER’S ORDERLINE: 1-800-247-5008
(to order parts)
SIG MODELER’S HOTLINE: [phone]
(for technical support)
SIG WEB SITE: www.sigmfg.com
LIMIT OF LIABILITY
The craftsmanship, attention to detail and actions of the builder/flyer of this
model airplane kit will ultimately determine the airworthiness, flight
performance and safety of the finished model. SIG MFG. CO.’s obligation
shall be to replace those parts of the kit proven to be defective or missing.
The user shall determine the suitability of the product for his or her
intended use and shall assume all risk and liability in connection therewith.

18
SPECIFICATIONS:
Engines: .40 to .46 2-Stroke
.52 to .70 4-Stroke
Wing Span: 54-1/2 in. (1384 mm)
Wing Area: 746 sq. in. (48.1 sq. dm.)
Length: 49-1/2 in. (1257 mm)
Flying Weight: 4.5 to 5 lb. (2041 to 2268 g)
Wing Loading: 13.9 to 15.4 oz. per sq. ft.
Radio: 4-channel with 5 servos