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Home
Lingo
explained
Effects of Pitch, Roll, Yaw & Throttle
How Much Does It Cost?
Model Trimming
NiCad Battery FAQ
Noise Levels
Balancing Propellers
Selecting a Propeller
Running In The Engine
What Channel Should I Use?
What the control sticks do?
What Transmitter should I buy?
Wheel Size?
Build Your Own Indoor
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Lingo Explained
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- 3D
- Term describing a type of flight pattern, which is characterized by the
performance of very specialized aerobatic manoeuvres below the model's normal
stall speed. Examples include torque rolls, 'walk in the park', harriers,
hangers, etc.
For helis: combining two or more manoeuvres into one
manoeuvre. Examples:
rolling circle, inverted backwards loop.
3F
- Slang abbreviation for flip flop flying. Similar to 3D, but without the
finesse.
360, 540, etc.
- Number describing degrees in an arc. A 360 represents one full turn through
an axis. A 360 turn, for example, is a flat turn where the aircraft does not
roll its wings but rather just 'slides' through 360 degrees turning on rudder
only.
-
For helis: A 540 stall turn, for example, describes a one and one half
revolution spin at the apex of a vertical stall, which results in the helicopter
resuming nose forward flight before recovery.
- ATL = Adjustable Throttle Limiter
- High-end feature which adjusts to bring full servo potential within the
limits of bind-free servo travel. Ideal for throttle control, or for more
effective braking in gas racing.
- ATV/EPA = Adjustable Travel Volume/End Point Adjustment
- Allows separate adjustments of maximum servo travel to both sides of
neutral. Helps tailor outputs for different control styles.
- Aileron Differential
- Creating larger upward aileron travel than downward aileron travel to
help minimize the model "dragging" the drooped aileron which causes a model
to yaw with aileron input.
- Ailerons
- Hinged control surfaces located on the trailing edge of the wing, one
on each side, which provide control of the airplane about the roll axis. The
control direction is often confusing to first time modellers. For a right roll
or turn, the right hand aileron is moved upward and the left hand aileron
downward, and vice versa for a left roll or turn.
- Ailevators
- Twin elevator servos plugged into separate channels used to control elevator
with the option to also have the 2 elevator servos act as ailerons in conjunction
with the primary ailerons.
- Airfoil
- The shape of the wing when looking at its profile. Usually a raindrop
type shape.
For helis: The rotor disk is the effective wing, and airfoil refers
to the shape of the blades.
- Angle of attack
- The angle that the wing penetrates the air. As the angle of attack increases
so does lift, up to a point (and drag).
- Articulated Rotor
- This is borrowed from full sized helicopters, and is a rotor head which
allows the blades to flap, drag and feather.
- Aspect ratio
- The ratio of the wingspan to the wing's chord (depth). For sailplanes
this number will be larger than sport planes, which will generally be larger
than a "jet" style aircraft.
- Autorotation
- The ability of a rotary wing aircraft to land safely without engine power.
This maneuver uses the stored energy in the rotor blades to produce lift at
the end of decent, allowing the model to land safely.
- Axis
- The line around which a body rotates.
- BEC = Battery Eliminator Circuitry
- Allows receiver to draw power from a main battery pack, eliminating the
need for (and weight of) a receiver battery.
- Ball Link
- Connection using a ball, and a link which rotates on the ball. Used to
connect the servo to a control surface or lever.
- Backlash
- Term describing the amount of play between gears, or gear mesh. If too
loose, the gear can slip, or strip the teeth. Too tight, and excessive wear
is caused.
- Base Load Antenna
- A rigid, short antenna mounted to the model. Used to replace the longer
receiver antenna.
- Bell and Hiller
- Control system used in helicopters. Changes pitch of blades in relation
to their position via a swashplate. A flybar with paddles is used to gain
responsiveness. The two systems are linked with Control Levers.
- Binding
- What occurs when the friction at a joint is stronger than the linkage.
- Boring holes in the sky
- Having fun flying an R/C airplane, without any pre-determined flight
pattern.
- "Buddy" or Trainer Box
- Two similar transmitters that are wired together with a "trainer cord."
This is most useful when learning to fly -- it's the same as having dual controls.
The instructor can take control by using the "trainer switch" on his transmitter.
- Butterfly
- Also known as crow. A mix which activates up flaperons and down inner-most
flaps for gliding speed control without spoilers or airbrakes.
- CA
- Abbreviation for cyanoacrylate. An instant type glue that is available
in various viscosities (Thin, Medium, Thick, and Gel). These glues are ideal
for the assembly of wood airplanes and other materials. NOTE: Most CA glues
will attack foam.
- CCPM
- Cyclic-Collective-Pitch-Mixing. Type of swashplate mixing which requires
a radio with CCPM mixing functions. This uses three servos to control the
cyclic, while all three work together to raise and lower the swashplate for
collective control.
- CG = "Center of Gravity"
- For modeling purposes, this is usually considered -- the point at which
the airplane balances fore to aft. This point is critical in regards to how
the airplane reacts in the air. A tail-heavy plane will be very snappy but
generally very unstable and susceptible to more frequent stalls. If the airplane
is nose heavy, it will tend to track better and be less sensitive to control
inputs, but, will generally drop its nose when the throttle is reduced to
idle. This makes the plane more difficult to land since it takes more effort
to hold the nose up. A nose heavy airplane will have to come in faster to
land safely.
- Carburetor
- The part of the engine which controls the speed or throttle setting and
lean/rich mixture via setting of the needle valve.
- Channel
- The frequency number used by the transmitter to send signals to the receiver.
If radios transmit on the same frequency, or channel, glitching will occur
in the active receiver on that channel. This is due to conflicting signals
sent by the two radios. Flying sites should have a frequency control system
to ensure that only one radio operates on any given channel at one time. This
is usually a board with some type of marker for each channel. If the marker
is not available, someone else is using that channel. Do not use your radio
unless you are sure you are the only one on the frequency.
- Channel
- The number of functions your radio can control. Ex: an 8 channel radio
has 8 available servo slots used for separate control surfaces or switches.
These channels can also be mixed on many radios, for such functions as collective,
which increases pitch when throttle is increased.
- Charge Jack
- The plug receptacle of the switch harness into which the charger is plugged
to charge the airborne battery. An expanded scale voltmeter (ESV) can also
be plugged into it to check battery voltage between flights. It is advisable
to mount the charge jack in an accessible area of the fuselage so an ESV can
be used without removing the wing.
- Charger
- Device used to recharge batteries and usually supplied with the radio
if NiCad batteries are included.
- Cyclic
- Term used for the horizontal controls used to determine the attitude
of the helicopter. Also known as elevator and aileron.
- DSC = Direct Servo Control
- High-end convenience feature which allows control/adjustment of servo
function without sending signal through receiver. Requires optional DSC cord
(FUTM4250) and DSC-compatible receiver such as R149DP and R113IP.
- Dead Stick
- A term used to describe unpowered flight (glide) when the engine quits
running.
- Dialed In
- Slang term for the condition in which the model is set up to fly smoothly
and predictably. This is the state where the mechanics and electronics work
together to produce the best performance.
- Differential
- Uneven movement in each direction of a control surface. Usually used
when discussing ailerons or when describing an undesired unevenness in movement
of other controls.
- Diode
- An electronic component which only allows current to flow one direction.
Protects the transmitter against reverse polarity or power surges during charging.
- Dual Conversion
- A type of receiver that converts the incoming frequency through two intermediate
stages. This tends to eliminate the type of interference known as "image".
With high-precision components, it also allows the receiver to be much more
precise in selecting the incoming channel it accepts. This is what helps the
receiver to be very narrow-band.
- Dual Rates
- A switch that can make controls more or less sensitive. Lower rates are
better for beginners, who tend to overcontrol.
- Elevator
- Hinged control surface located at the trailing edge of the horizontal
stabilizer, which provides control of the airplane about the pitch axis and
causes the airplane to climb or dive. The correct direction of control is
to pull the transmitter elevator control stick back, toward the bottom of
the transmitter, to move the elevator upward, which causes the airplane to
climb, and vice versa to dive.
- Elevator-to-Flap Mixing
- Used to apply flaps along with elevators to increase lift, allowing modeler
to fly at slower speeds, make tighter loops or turns, etc.
- Epoxy
- A two-part resin/hardener glue that is extremely strong. It is generally
available in 6 and 30-minute formulas. Used for critical points in the aircraft
where high strength is necessary.
- Expanded Scale Voltmeter (ESV)
- Device used to read the battery voltage of the on- board battery pack
or transmitter battery pack.
- Exponential Rate
- Offers servo travel that is not directly proportional to stick travel.
Control response is milder below half-stick, but becomes increasing stronger
as stick travel approaches 100%. Great for aerobatics and trouble situations.
- FM
- Frequency Modulation. This describes the mode of transmission of radio
signal from transmitter to receiver.
- Fail Safe
- A safety feature which turns a servo to a preset position if the signal
is lost or interrupted. Additionally, battery failsafe is a safety feature
which brings the throttle servo down to idle as a warning that the receiver
battery's voltage is getting dangerously low.
- Field charger
- A fast battery charger designed to work from a 12-volt power source,
such as a car battery.
- Flaperons
- The movement of two aileron servos, both in the same direction at the
same time, acting as flaps.
-
- Flaps
- Hinged control surface located at the trailing edge of the wing inboard
of the ailerons. The flaps are lowered to produce more aerodynamic lift from
the wing, allowing a slower takeoff and landing speed. Flaps are often found
on scale models, but usually not on basic trainers.
- Flare
- The point during the landing approach in which the pilot gives an increased
amount of up elevator to smooth the touchdown of the airplane.
- Flight Box
- A special box used to hold and transport all equipment used at the flying
field.
- Flight Pack or Airborne Pack
- All of the radio equipment installed in the airplane, i.e., Receiver,
Servos, Battery, Switch harness.
- Flutter
- A phenomenon whereby the elevator or aileron control surface begins to
oscillate violently in flight. This can sometimes cause the surface to break
away from the aircraft and cause a crash. There are many reasons for this,
but the most common are excessive hinge gap or excessive "slop" in the pushrod
connections and control horns. If you ever hear a low-pitched buzzing sound,
reduce throttle and land immediately.
- Frequency Control
- The FCC has allowed the 72MHz (72.010 - 72.990) band to be used for R/C
aircraft operations. This band is divided up into many different channels
in which you can choose a radio system. You should be aware that certain areas
have frequencies in which there is pager interference. This is why it is always
a wise move to check with your local hobby shop to find out any channels that
may be troublesome in the area you wish to fly. The FCC has allowed band 75MHz
(75.410 through 75.990) for ground model use only (robots, battlebots, cars,
boats), 50MHz (50.800 - 50.980) is allocated only to Amateur HAM license holders
for R/C use (and only at 1W maximum power output.)
- Fuselage
- The body of an airplane.
- Gain
- Gyro sensitivity. When too low, the tail will not hold position well.
When too high, the surface being dampened by the gyro will tend to wag, or
hunt for center.
- Glitch
- Momentary radio problem that never happens unless you are over trees
or a swamp.
- Glow Plug
- The heat source for igniting the fuel/air mixture in the engine. When
starting the engine a battery is used to heat the filament. After the engine
is running, the battery can be removed. The wire filament inside the plug
is kept hot by the "explosions" in the engine's cylinder. See next heading
and "Idle Bar" plug.
- Gyro
- A gyro is an electro-mechanical, or electronic device which aids in the
control of an R/C model. The gyro senses motion in one axis, and directs the
servo to counter that motion. The sensor, which can be a mechanical gyroscope,
or an electronic piezo crystal, detects unwanted movement. The gyro then instructs
the servo to counter for that motion. At all times, the radio commands will
override the gyro command. The level of control the gyro had is adjusted by
the GAIN setting.
Mechanical Gyro: uses a mechanical gyroscope (similar to the child's toy)
to sense movement.
Piezo Gyro: uses a piezo crystal to sense movement.
Non-Heading-hold vs. heading hold: A standard (nonHH) gyro senses movement
and makes an effort to counter that movement as long as it feels it. Therefore,
it is NOT going to return the model to the exact heading prior to the movement.
Heading Hold (or AVCS) gyros will lock the model into one position, and accurately
correct for movement by sensing rate of change and returning at that same
rate.
SMM technology: utilizes a microchip to sense movement and provide all readings.
Experiences minimal effect from temperature change, commonly known as 'temperature
drift' which affects piezo and some mechanical gyros.
- Heading Hold
- This describes a type of Gyro which senses rotation, and maintains direction.
This is accomplished by sensing the rate of motion, and the time of motion,
then compensating for the distance. While this sounds complicated, the effect
is that if you have the model dialed in, and point the nose north, with a
heading hold gyro on the yaw axis the model will continue to face north until
you command it to yaw. See also Heading Lock. This is not recommended for
aircraft use while in flight due to the requirement to use YAW (rudder) command
to turn the model. Often used for ground use only for perfect take off and
landing runs.
- Heading Lock
- Slang term for Heading Hold Gyro.
- Helicopter Radio
- A remote control radio system designed specifically for use with helicopter
models. The helicopter radio differs from an aircraft radio in a few ways.
First, the heli radio needs mixing functions specific to helicopters, and
usually a minimum of five channels. Collective mixing for collective pitch
helicopters is a necessity. Second is the throttle stick, which is ratcheted
in airplane transmitters, will not have the clicking feel on the heli version.
This is due to the precise control needed on the heli collective stick to
achieve and sustain a controlled hover. The specific radio requirements will
vary from user to user, and the parameters used will vary from helicopter
to helicopter. Note that many radios produced have both airplane and helicopter
programming in a single radio.
- Hit (or to be hit)
- Sudden radio interference which causes your model to fly in an erratic
manner. Most often caused by someone turning on a radio that is on your frequency,
but can be caused by other radio sources miles away.
- Horizontal Stabilizer
- The horizontal tail surface at the back of the fuselage which provides
aerodynamic pitch stability to the airplane.
- Idle Up
- This is a setting on the transmitter which limits the throttle minimum.
Particularly useful for FFF and 3D stunt flying.
- Inverted
- To fly a model upside-down.
- Inverted Flight Control
- Activates inverted flight programming for helis, which reverses the direction
of the rudder, pitch and elevator servos, and sets up inverted flight pitch
high-side and low-side. Inverted programming is used to allow the radio inputs
to be identical to upright flight while the model is inverted. Note: this
approach to hovering is seldom used. Instead, idle-ups are used and the modeler
learns to understand and respond to the controls' reversal in inverted flight.
- Leading Edge (LE)
- The very front edge of the wing or stabilizer. This is the edge that
hits the air first.
- mHz = Megahertz
- The unit of radio frequency. 75 mHz are surface frequencies; 72 mHz are
air frequencies; 27 mHz and 50 mHz can be used for either ground or air applications.
Note: Use of the 50 mHz (ham radio) band requires an FCC license.
- Mixing
- Allows a single input to control the operation of two or more servos.
Simplifies routine flying and allows more involved maneuvers -- great for
intermediate-advanced fliers. For example, Flap-to-elevator mixing: Most models
will change pitch upon deploying flaps (some will climb; others dive). After
test flying the model and determining the direction and amount of elevator
throw required to correct for this change, a pilot may set a flap-to-elevator
mix to compensate. Once the mix is operating properly, when the modeler gives
flap control, the radio automatically also gives the proportional amount of
elevator throw, keeping the model flat and straight.
- Mixing Arm
- A specialized lever which has three or more pivots. The length between
pivots will determine the proportion of the mix between two or more linkages.
- Module
- A removable/replacable plug in unit used in most complex computer radios,
containing all frequency control equipment, including the crystal and all
tuned components. Changing channels or bands on a modular radio requires only
changing module. Changing crystals WITHIN a module to change the channel of
the module itself is against FCC regulation and is not recommended. To use
your transmitter on a different channel you simply purchase another module
on that other channel and the radio is now fully properly tuned and safe and
easy to use on that other channel as well.
- Narrow-Band
- A radio with a 20 KHz band width. All Futaba radios produced 1992 or
later and all Futaba FM and PCM radios ever produced are narrow band.
- NiCad (or NiCd) = Nickel Cadmium battery
- Rechargeable batteries which are typically used as power for radio transmitters
and receivers.
- Nitro = Nitromethane
- A fuel additive which increases a model engine's ability to idle low
and improves high speed performance. Ideal nitro content varies from engine
to engine. Refer to the engine manufacturer's instructions for best results.
Nitro content in fuel is indicated by the percent of the fuel.
- PA2 = Pilot Assist
- Optional onboard device which uses optical sensors to correct model's
orientation to upright.
- PCM = Pulse Code Modulation
- PCM systems use digitally encoded signals to minimize interference and
provide today's most advanced R/C control.
- PPM
- Pulse Position Modulation. Another term for FM.
- Peak
- This is the point at which a battery will no longer accept a charge,
and converts the energy to heat. This is damaging to the battery pack, and
potentially hazardous.
- Peak Charger
- This type of charger will eliminate the guesswork. When the battery has
reached peak, the charger reverts to a maintenance charge rate, which will
not damage the pack.
- Pitch Axis
- The airplane axis controlled by the elevator. Pitch is illustrated by
holding the airplane at each wingtip. Raising or lowering the nose is the
pitch movement. This is how the climb or dive is controlled.
- Pitch Curve
- The programming function of the radio which aids in setting the hover
point, and end points of the blade pitch in the collective mix.
- Pitch Trim
- Offsets the entire heli pitch curve, increasing or decreasing responsiveness
proportionally at all points.
- Power Panel
- 12-volt distribution panel that provides correct voltage for accessories
like glow-plug clips, fuel pumps and electric starters. Usually mounted on
a field box and connected to a 12-volt battery.
- Pull-Pull
- A linkage set up using two rods or wires. One is pulled for one direction,
the other is pulled for the other.
- Push-Pull
- A linkage set up using two rods. One rod pushes, while the other pulls.
- Receiver (Rx)
- The radio unit in the airplane which receives the transmitter signal
and relays the control to the servos. This is somewhat similar to the radio
you may have in your family automobile, except the radio in the airplane perceives
commands from the transmitter, while the radio in your car perceives music
from the radio station.
- Resonance
- This is the vibration frequency of a rotating or moving object. When
the resonance of many parts of a machine are in synch, the whole machine will
vibrate at a greater rate. This can cause vibration damage. Resonance can
cause difficulties in an aircraft, particularly when using a vibration mount
with an improperly balanced propeller/spinner wherein the engine is vibrating
at one frequency and the propeller at another.
For helis: Keep in mind that a helicopter has many rotating parts, and
they all cause resonance. The helicopter will need to be tuned to reduce
the amount of resonance, and the vibration caused by resonance. While this
cannot be eliminated, the vibrations can be tuned individually to reduce
the overall vibration of the helicopter.
- Retract Servo
- Specifically used for mechanical retracts. It is a non-proportional servo
which only moves 180 degrees. That is to say this servo is either "off" (gear
up and fully locked) or "on" (gear down and fully locked). No ATV, EPA, or
AST adjustments can be made on these servos because they are not proportional.
The linkage must be set up properly to allow this servo to operate at its
full range and do its job -- securing your model's landing gear in a gear-up
or gear-down position.
- Revolution Mixing
- The function of the radio which mixes throttle to rudder, preventing
the rotation of the helicopter during throttle increase or decrease.
- Roll Axis
- The airplane axis controlled by the ailerons. Roll is illustrated by
holding the airplane by the nose and tail. Dropping either wingtip is the
roll movement. This is used to bank or turn the airplane. Many aircraft are
not equipped with ailerons and the Roll and Yaw motions are controlled by
the rudder. This is one reason why most trainer aircraft have a larger amount
of dihedral.
- Rudder
- Hinged control surface located at the trailing edge of the vertical stabilizer,
which provides control of the airplane about the Yaw axis and causes the airplane
to Yaw left or right. Left rudder movement causes the airplane to Yaw left,
and right rudder movement causes it to Yaw right.
- Rudder Offset
- In radios with idle up functions, this specifies the amount of tail rotor
pitch in the different idle up conditions.
- Rudder-to-Aileron
- Mix used to counteract undesirable roll which often happens with rudder
input, especially in knife edge, also called roll coupling.
- Rudder-to-Throttle
- This heli mix adds a small amount of throttle to counter the added load
on the main gear from increasing the pitch of the tail blades, helping to
maintain a constant headspeed during rudder application. (This is a minor
effect and is not a critical mix for most helicopters.)
- Rx
- Abbreviation for receiver.
- SMT = Surface Mount Technology
- Ultralight, solid-state components which offer greater vibration resistance
and reliability.
- Servo
- The electro-mechanical device which moves the control surfaces or throttle
of the airplane according to commands from the receiver. The radio device
which does the physical work inside the airplane.
- Servo Reversing
- Reverses the rotation of a servo with the flip of a switch. Adds ease
and flexilibility during installation.
- Servo Output Arm
- The removable arm or wheel which bolts to the output shaft of a servo
and connects to the pushrod.
- Servo Reversing
- Used to reverse the direction of a servo to ease installation and set
up.
- Shot down
- A "hit" that results in a crash landing. Sometimes caused by radios miles
away.
- Slop
- Unwanted, excessive free movement in a control system. Often caused by
a hole in a servo arm or control horn that is too big for the pushrod wire
or clevis pin. This condition allows the control surface to move without transmitter
stick movement. Also, see flutter.
- Snap Roll Switch
- Combines rudder, elevator and aileron movement to cause the aircraft
to snap or spin on the flip of a switch.
- Solo
- Your first totally unassisted flight that results in a controlled landing.
- Speed Flap
- The middle control surface on a 6-trailing-edge-surface glider or the
inboard control surface on a 4-surface glider.
- Stall
- What happens when the angle of attack is too great to generate lift regardless
of airspeed. (Every airfoil has an angle of attack at which it generates maximum
lift -- the airfoil will stall beyond this angle).
- Sub-Trim
- This is a trim function on many computer radios, allowing trim function
during set-up, and still allowing the full trim function in flight.
- Tachometer
- An optical sensor designed specifically to count light impulses through
a turning propeller and read out the engine RPM.
- Throttle Curve
- The programming function of the radio which allows throttle operation
to be adjusted to meet the modeler's specific needs at various points along
the throttle movement. Particularly useful with 2-stroke engines in providing
linear throttle response at the various points of throttle application.
For helis: Aids in setting the hover point, and end points of the throttle
in the collective mix.
- Throttle Hold
- A radio function which locks the throttle at a fixed point while a switch
is activated. This function is used to hold the throttle in an idle. Useful
when starting, as well as for auto rotations.
- Torque
- The force which tends to cause rotation.
- Trailing Edge (TE)
- The rearmost edge of the wing or stabilizer.
- Trainer Airplane
- A model designed to be inherently stable and fly at low speeds, to give
first-time modelers time to think and react as they learn to fly.
- Trainer System
- Allows trainer to link radios with a student via a cord, and to instantly
take control of student's craft in-flight.
- Transmitter (Tx)
- The hand-held radio controller. This is the unit that sends out the commands
that you input.
- Tx
- Abbreviation for transmitter.
- V-tail Model Mixing
- Used on a V-tail model to have two servos operate two control surfaces
as both rudder and elevator.
- Vertical Fin
- The non-moving surface that is perpendicular to the horizontal stabilizer
and provides yaw stability. This is the surface to which the rudder attaches.
- Washout
- An intentional twist in the wing, causing the wing tips to have a lower
angle of attack than the wing root. In other words, the trailing edge is higher
than the leading edge at the wing tips. Washout helps prevent tip stalls,
and helps the "PT" family of trainers recover, hands-off, from unwanted spiral
dives.
- Wing
- The main lifting surface of an airplane.
- Yaw Axis
- The airplane axis controlled by the rudder. Yaw is illustrated by hanging
the airplane level by a wire located at the center of gravity. Left or right
movement of the nose is the Yaw movement.
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