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Aircraft
Terms Aileron An Aileron is a moveable surface on the
trailing edge of the wing which provides directional
control of the roll of the aircraft. A Strip Aileron
is an aileron that is narrow and usually takes up the
entire, or most of the trailing edge of a wing. A
Barn-door Aileron is wider and takes up a smaller
portion of the trailing edge towards the wing tip. Airfoil The Airfoil is the shape of the cross
section of the wing. The front of the airfoil is the
leading edge and is usually a rounded section. The
back of the airfoil is the trailing edge and usually
tapers to nearly a point. The distance between the two
is the wing chord. The top surface of the airfoil is
usually always curved to allow smooth airflow and
produce lift. Ballast Ballast is extra weight added to a glider to
help it penetrate better in windy weather or to
increase its speed. Ballast is usually added in tubes
in the inner portion of the wings or in the fuselage
at the center of gravity. Center
of Gravity The Center of Gravity is the position in the
aircraft where if a point was placed, the plane would
balance. The “C of G” should usually be found along
the centre line of the aircraft at a distance
approximately 1/3 of the way behind the leading edge
of the wing. Clevis The Clevis is a small fastener at the end of
a push rod, usually made from nylon or metal, which
connects the push rod to the control horn. Clevises
may frequently be referred to as links. Control
Horn The Control Horn is a small bracket mounted
on a control surface to transfer the movement of the
push rod to the control surface. Control
Surface A moveable surface, attached to the
air-frame of an aircraft, which controls the direction
of the aircraft. Conventional
Tail A Conventional Tail is one with the
stabilizer mounted directly on the fuselage and is the
usual configuration of an aircraft. These are the
simplest to construct and seem to be most popular. Covering The covering of an aircraft is the skin
which is applied to the air-frame, closing it in. On
RC aircraft it is commonly a fabric or plastic which
is heat applied with an iron. Plastic covering, once
applied, gives a durable, shiny finish and requires no
further treatment. Fabric covering usually requires a
layer of paint to finish it and make it resistant to
the exhaust of the engine. Covering materials come on
a roll and in many different colors and may be cut to
rough shape before being ironed onto the air-frame. Crucifix
tail Crucifix tail refers to a stabilizer that is
mounted part way up the fin. This is a compromise
between the conventional tail and the T-tail,
combining some of the major advantages of both. Dihedral
The Dihedral of a wing is the V shape the
wing makes or the angle between the wing and the
horizontal. Usually the greater the dihedral angle the
more stable the aircraft will be (to a point) and is
common in trainer type aircraft. A flat wing with
little or no dihedral is less stable and more suited
to aerobatics. Elevator
The Elevator is the horizontal moveable
control surface at the tail of the model connected to
the stabilizer. It controls direction in pitch. Engine
mount An engine mount supports the engine in an
aircraft. Some aircraft use wooden rails to which the
engine is mounted while others require a shaped nylon
or aluminum mount. The wooden rail type would usually
be included in a kit while the molded type may or may
not be included, depending upon the kit. It is
possible to get mounts specifically for a particular
engine, although many generic type mounts are
available to fit certain engine size ranges. Fin
The Fin, also known as the “vertical
stabilizer”, is the fixed vertical surface at the rear
of an aircraft. It provides yaw stability for the
aircraft. Flap
The Flap is a control surface found on some
aircraft, usually located on the inboard trailing edge
of each wing. Flaps may be lowered to increase the
lift of the aircraft by simulating an under-camber
airfoil. Flat
Bottom A Flat Bottom Wing is when the lower surface
of the wing is primarily flat between the leading and
trailing edges. This type of wing has high lift and is
common on trainer type aircraft. Flex
Cable A Flex Cable is a special type of push rod
which is very flexible and can bend around corners
even more easily than a flexible push rod. These are
generally made with a metal cable running inside a
plastic tube and are popular in controlling the engine
throttle. Flying
Stab A flying stab is where the
stabilizer/elevator is one complete unit which all
moves to control the pitch of the aircraft. Foam
Rubber Foam rubber is used to wrap the radio
receiver and receiver battery pack in the plane so
that they will be isolated from the vibration of the
running engine. Fuselage
The fuselage is the body part of the
aircraft which holds the passengers, cargo, or in the
case of an RC aircraft, the radio system. Glide
Ratio The glide ratio is defined as the distance
traveled in a horizontal direction compared with the
vertical distance dropped on a normal glide. A 10 to 1
glide ratio means that the aircraft would loose one
foot of altitude for every ten feet of distance
traveled. Hinges The hinges are used to connect the moveable
control surfaces of the aircraft to the fixed surfaces
and allow smooth, easy movement. They may take several
forms including hinge points, pinned hinges, “living”
hinges, etc. Landing
Gear The landing gear of the aircraft refers to
the support between the wheels and the wing or
fuselage. It is usually formed from metal, wire or a
nylon/fiberglass combination. Pitch The pitch refers to the angle of the
aircraft in the up or down direction. Polyhedral Polyhedral refers to the multiple angles
that wing panels make with the horizontal. A wing with
polyhedral has more than two wing panels and the angle
of the wing changes at each joint. Propellers The propeller is the device that converts
the rotational action of the motor into movement of
air that creates the thrust to power the aircraft. The
size of an aircraft propeller is described by two
numbers—the diameter in inches times the pitch in
inches. For example, a 10 x 6 propeller is a prop of
10” diameter and having 6” of pitch. The diameter is
simply the length of the prop. The pitch is described
as the distance the propeller will move ahead in a
perfect or solid medium, at 100% efficiency, in one
revolution. That is to say, if you were to rotate your
10 x 6 propeller exactly once, your plane would move
ahead 6”, assuming this could be done with no
slippage. Push-rod
Connectors The push rod connector is another means by
which a push rod may be connected to a servo. The
connector is mount a servo arm and the push rod wire
is secured by a set screw. Push-rods The push-rods are part of the control
linkage which connects the servo part of the radio
system to the control surfaces of the aircraft.
Push-rods may consist of a firm piece of balsa or
fiberglass rod with threaded wire and clevises
fastened to both ends, or they may be the flexible
type and take the form of a wire or one plastic tube
running inside another with the ability to turn around
corners. Roll The roll refers to the rotation of the
aircraft around it’s center-line (one wing up and one
wing down). Rudder
The Rudder is the moveable control surface
at the tail of the model connected to the fin. It
controls direction in yaw. Semi-symmetrical A semi-symmetrical airfoil has a curved wing
bottom surface but to a lesser degree than the top
surface. It is a compromise between the flat bottom
and the symmetrical airfoil. This is a very popular
airfoil on sport type aircraft. Spinner
The spinner is the cone shaped object
mounted to the engine prop shaft on the nose of the
aircraft. The spinner may be made from plastic or
aluminum and functions primarily to improve looks and
aerodynamics. Spoiler A Spoiler is a control surface more commonly
found on gliders and jet aircraft which is used to
slow down the aircraft and decrease lift. They are
rarely found on conventional aircraft. They may be
mounted on either the top or bottom of the center
portion of the wings. Stabilizer
The Stabilizer is the fixed horizontal
surface at the rear of an aircraft. It provides pitch
stability for the aircraft. Symmetrical A Symmetrical airfoil is curved on the
bottom to the same degree as it is on the top. If a
line was drawn from the center of the leading edge to
the center of the trailing edge the upper and lower
halves of the airfoil would be symmetrical. This is
ideal for aerobatic aircraft and most lift is created
by the angle of incidence of the wing to the flight
path. Tail
Dragger This refers to the landing gear
configuration where the main landing gear with two
wheels is placed forward of the center of gravity and
one small wheel, called a “tail wheel”, is mounted
under the tail of the aircraft. Tow-hook
The tow-hook is a small metal hook mounted
on the bottom of the glider fuselage at approximately
the center of gravity and to which the hi-start or
winch is connected. Tricycle
Landing Gear Tricycle refers to the landing gear
configuration with a single steerable nose-wheel
mounted in front of the center of gravity, and a set
of main landing gear with two wheels positioned just
behind the center of gravity. Tricycle landing gear is
usually a little easier to use when learning. T-tail
The T-tail refers to a stabilizer that is
mounted on top of the fin. This brings the stabilizer
away from the turbulent air-flow of the wing and makes
pitch control more responsive. It also gets the
stabilizer out of harms way when landing on rough
terrain. The T-tail construction is usually more
fragile than the conventional tail, though, and are
more difficult to build. Under-camber An Under-camber airfoil has the lower
surface of the wing curved inwardly almost parallel to
the upper surface . This type of airfoil produces a
great deal of lift but is not common in R/C models. Undercarriage Another name for landing gear (see landing
gear) V-Tail A V-Tail is a special tail surface
configuration where the horizontal stabilizers and
elevators are mounted at an angle between 30 and 45
degrees in a V-shape and the vertical fin is
eliminated entirely. The stabilizers provide stability
in both pitch and yaw while the moveable surfaces
provide directional control in both pitch and yaw. Wheel
Collars Wheel Collars are small metal collars
fastened with a set screw to the axle of an aircraft
on either side of the wheel. This prevents the wheel
from coming off the axle or rubbing against the
landing gear. Wheels
The wheels for an aircraft come in several
styles including treaded, non-treaded, scale tread,
air-filled, and super lightweight. Most brands of
wheels are available in sizes from 1¾” to 6”, in 1/4”
increments. Wing
The wing of the aircraft is the large
horizontal surface which produces the lift and allows
the aircraft to fly. Wing placement may be on the
upper part of the fuselage known as a high wing plane.
This is more common on trainer type aircraft as a high
wing model is more stable due to the pendulum effect
of the fuselage. A wing mounted on the bottom of the
fuselage is referred to as a low-wing aircraft and is
more suitable for aerobatic type aircraft as stability
is more neutral and maneuvers such as rolls and loops
are more easily done. Wing
Area The Wing Area is the total surface area of
the wing of the aircraft, usually calculated by the
wingspan times the wing chord, although more complex
calculations re used on unconventional wing plans. Wing
Chord The wing chord of an aircraft is the
distance from the front or “leading edge” of a wing to
the back or “trailing edge” Wing
loading Wing loading is defined as the weight of the
aircraft divided by the wing area. It is usually
expressed in ounces per square foot. Wing
Seating Tape Wing seating tape is mounted on the fuselage
wing saddle where the removable wing fits and isolates
the wing from vibration as well as to form a seal to
keep exhaust gases from entering the structure. Wing
Span The Wingspan of an aircraft is the length of
the wing as measured from wing tip to wing tip. Wing
Tip The very outer edge of a wing. Yaw The yaw refers to the angle of the aircraft
in the side to side direction.
Radio
Terms Adjustable
Function Rate (AFR) Similar to ATV, AFR allows end point
adjustment independent of dual rate or exponential
settings. Adjustable
Travel Volume (ATV) An adjustment that lets you preset the
maximum travel of a servo to either side of neutral. Aileron
Extension The aileron extension (servo extension) is a
cable with connectors on either end which goes between
the receiver and a servo. This allows the servo to be
placed at a greater distance from the receiver than
the cable that comes on the servo will allow. It also
permits easier removal of a wing when the servo that
controls the aileron is mounted in the wing and the
receiver is in the fuselage (which is usually the
case). One aileron extension is usually included with
a radio system of four or more channels. Aileron
Extensions of various lengths are available from
different manufacturers. Please note: long aileron
extensions can sometimes cause radio interference
problems unless “noise traps” are used. Amplitude
Modulation (AM) Was initially the primary means of radio
modulation used in RC until recently. The control
information is transmitted by varying the amplitude of
the signal. AM is now used in only less sophisticated
systems. Buddy
Box The ability to connect two transmitters
together, either wireless or wired, for training
purposes. Channel There are two definitions for the word
channel in radio control. 1. It can refer to the
channel number or frequency of operation of a control
system. 2. It may also refer to one of the operating
functions of a radio system. For example, a 4-channel
radio system would have four control functions:
aileron, rudder, throttle and elevator. Crystal An electronic component of the radio that
determines the frequency of operation. There is one in
the receiver and one in the transmitter. Digital
Trims Digital trims utilize a spring loaded slide
switch rather than a potentiometer to adjust trims
using digital messages. Direct
Servo Controller (DSC) Allows full function of an aircraft’s servos
via an umbilical cord. This permits adjustment of
radio functions without switching on the RF portion of
a transmitter. Dual
Aileron Extension The Y-Harness is a cable which plugs into a
single channel in a receiver and two servos. This
allows both servos to be operated from the same
channel. Dual
Conversion Dual conversion refers to the method in
which the receiver processes the incoming signal.
Generally a dual conversion receiver is less prone to
outside interference and is the preferred type of
receiver. Dual
Rates (D/R) Dual Rate allows the modeler to choose
between two different control sensitivities. With the
dual rate switch in the “OFF” position, 100% servo
throw is available for maximum control response. In
some more sophisticated systems this “OFF” position
may be adjusted to provide anywhere from 30% to 120%
of normal full throw. In the “ON” position, servo
throw is reduced and the control response is
effectively desensitized. The amount of throw in the
Dual Rate “ON” position is usually adjustable from 30%
to 100% of total servo movement. The modeler can
tailor the sensitivity of his model to his own
preferences. End
Point Adjustment The ability to adjust one end of a servo
travel only. Similar to Adjustable Travel Volume, but
for adjustment on one side of neutral only. Exponential
Rate Exponential Rate is where the servo movement
is not directly proportional to the amount of control
stick movement. Over the first half of the stick
travel, the servo moves less than the stick. This
makes control response milder and smooths out level
flight and normal flight maneuvers. Over the extreme
half of the stick travel, the servo gradually catches
up with the stick throw, achieving 100% servo travel
at full stick throw for aerobatics or trouble
situations. Fail
Safe (FS) An electronically programmed mechanism in
most PCM radios to automatically return a servo or
servos to neutral or a preset position in case of
radio malfunction or interference. Flight
Modes The ability for a radio system to switch
between different types of flying, particularly in
helicopters. Different parameters may be committed to
the transmitter’s memory and selected using a “flight
mode” switch. Frequency
Flag The frequency flag is a marker that is
mounted on your transmitter to indicate what frequency
your system is operating on to alert other modelers so
as not to cause interference. Frequency
Modulation (FM) Now the most common method of radio
modulation in RC, FM is less prone to interference
than AM. Information is transmitted by varying the
frequency of the signal Idle
Up The function of a helicopter radio to first
bring the throttle and rotor speed up before adding
collective pitch. Mixing Mixing is the ability to have one channel of
control input at the transmitter affect more than one
receiver channel and servo movement. Mode
I The control stick configuration with the
rudder and elevator being controlled by the left stick
while the right stick controls the throttle and
ailerons. This is popular in Europe. Mode
II The control stick configuration with the
ailerons and elevator being controlled by the right
stick while the left stick controls the rudder and
throttle. This is the normal set-up for aircraft in
North America. Mode
IV The control stick configuration with the
rudder and elevator being controlled by the right
stick while the left stick controls the ailerons and
throttle. This is similar to Mode 1 except that the
sticks are reversed. Some find this mode more
desirable for flying aerobatics than the default Mode
II. Model
Memory Allows the storage of information for more
than one model. Very convenient for only having to set
reversing, trim, mixing, etc for a model once and
still be able to use the transmitter for more than one
model. Modulation The way the electronic control information
is sent from your transmitter to the receiver through
radio waves. Noise
Traps A noise trap is a small electronic device
which is wired into a long servo extension to reduce
radio interference and to boost the control signal
going to the servo. These are recommended for use
where long servo leads are necessary. Pitch
Curve The pitch curve is the relation between the
position of your transmitter control stick for
collective pitch and the actual pitch of the rotor
blades. It is desirable to have adjustable pitch curve
points on a helicopter radio—the more the better. That
way one can customize the collective response
according to the type of flying. Pulse-Code
Modulation (PCM) A special digital encoding of a frequency
modulated signal. FM is still utilized, however, the
control information is in the form of a digital word
rather than just a pulse width, as is used with
standard AM or FM. Using PCM adds additional
protection against interference from various sources. Servo
Control Arms Servo Control Arms are the plastic output
horns which are mounted to the output shaft on your
servos. These come in various sizes and styles for
different control applications. Most servos will come
with an assortment of arms so you can customize to
your own specific control needs. Servo
Extension Same as aileron extension. Servo
Reversing This feature allows the modeler to reverse a
servo’s rotation direction at the flip of a switch.
Permits servos to be mounted in the most convenient
way without concern for their rotation direction. The
proper movement can then be selected when the
installation is completed. Servo
Torque The measure of power of a servo as measured
in ounce-inches (the number of oz. the servo can push
with a 1” control arm) Servo
Tray A Servo tray is a plastic tray which
facilitates mounting your servos easily in your model.
The tray is molded to hold your servos securely and
ensure positive control to your control surfaces.
Different trays may hold anywhere from one to four
servos and are shaped for different uses and servo
positions in your model. Snap
Roll Button This feature is found on more complex radios
and is used to perform a snap roll maneuver by simply
pressing one button. The function is usually
programmable to give a combination of rudder, elevator
and aileron control. Sub
Trim A radio function which allows very precise
electronic centering of servos. Switch Harness - The
switch harness is mounted in your model and it
connects between your receiver and the NiCd battery
pack. It provides a power ON/OFF switch to the radio
in your model and it also allows your charger to be
connected to your model’s battery pack for charging. Synthesized
Frequency A more sophisticated method of controlling
the frequency of a radio control system than crystals.
Synthesizing is more expensive than crystals, however,
it gives you the opportunity of selecting from a whole
band of frequencies on which to operate. This allows
you to obtain a clear frequency at the field—no more
waiting for a crystal controlled frequency to become
clear. Trainer
System The trainer system feature allows two
transmitters of similar design to be connected
together via a cord (trainer cord) so that one
transmitter may be used by an instructor and the
second one by a student when learning to fly. The
instructor simply has to hold a switch on his
transmitter to give the student’s transmitter full
control. If the student gets into trouble, the
instructor can release the switch and he has full
control of the model. Variable
Trace Rate (VTR) This radio function is similar to
exponential except it uses two linear responses to
determine the servo sensitivity on the first and
second half of the control stick movement. Y-Harness Same as a Dual Aileron Extension. Programmable
Mixing Terms Programmable Mixing is the electronic
coupling of one channel to another. One control input
will yield output to two different servos. Aileron/Rudder
Mixing Adds rudder control when aileron is input
from the transmitter aileron stick. V-Tail
Mixing Used when there is a V-Tail on the aircraft
rather than the conventional elevator and rudder. Each
control surface of the V is connected to a separate
servo. Operating the elevator control stick will move
both surfaces up for back stick or both surfaces down
for forward stick. Moving the rudder control stick
left will move the left surface of the V down and the
right surface up. Moving the rudder control stick to
the right will move the left surface of the V up and
the right surface down. Flaperon
Mixing Mixes the Flap and Aileron functions so that
when each aileron is connected to a separate servo
(one servo plugged into the aileron channel and the
other plugged into the flap channel), the surfaces
will act as both ailerons and flaps, depending on the
position of the controls. Elevon
Mixing Mixes the elevator and aileron functions,
especially useful for delta wing models where the
elevator and ailerons are the same control surfaces.
Each surface is connected to a separate servo (one
servo plugged into the aileron channel and the other
plugged into the elevator channel), the surfaces will
act as both ailerons and elevator, depending on the
position of the controls. Flap/Elevator
Mixing Couples the flaps and elevators such that
when the flaps are lowered, the elevator will be
automatically adjusted to prevent pitching of the
model. Elevator/Flap
Mixing Couples the elevators and flaps such that
when control is input to the elevators, the flaps will
move in the opposite direction. This permits the model
to perform tighter maneuvers in the pitch attitude. Crow
Mixing Primarily used in gliders for spoiler action
by mixing the flaps and ailerons. It is necessary for
the ailerons to be using separate servos, plugged into
separate channels and the flap servo to be independent
of both aileron channels. Upon applying Crow Mixing,
the flaps go down while both ailerons go up. CCPM
Mixing Cyclic/Collective Pitch Mixing is used
exclusively in helicopters and eliminates much of the
complicated linkages required on a conventional setup.
CCPM is a system which mounts 3 servos below the swash
plate, with short, straight linkages directly to the
swash plate at 120 degree intervals. With CCPM,
complex collective and cyclic mixing is accomplished
electronically, rather then mechanically. As a result,
many parts are eliminated, along with excessive
control system play—not to mention the quicker
building time and lower required maintenance.
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