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RC Dictionary
Below is a list of common radio controlled terms and their meaning.
ABC / Non-Ringed - These letters stand for aluminum, brass and
chrome or a composite such as nickel. These engines have an aluminum
piston and a chrome or composite coated brass cylinder sleeve which
allows them to be more efficient for higher performance. They have
no piston ring and rely on a very tight piston/cylinder fit to obtain
a piston/cylinder seal. New ABC engines are normally hard to turn
over by hand. Because of the tight fit, it is very important that
the engine is broken in properly.
Adjustable Travel Volume (ATV) - ATV allows you to preset the maximum
travel of a servo to either side from its neutral position. Such
settings help tailor control action to suit your flying or driving
style.
Adverse Yaw - The tendency of an airplane to yaw in the opposite
direction of the roll. For instance, when right aileron is applied,
the airplane yaws to the left, thus opposing the turn. Adverse yaw
is common in trainer type airplanes having flat bottom wings. It
is most noticeable at slow speeds and high angles of attack, such
as during takeoffs and when stretching a landing approach. Caused
by the unequal drag of the upward and downward deflection of the
ailerons, this undesirable trait can be minimized by setting up
the ailerons with Differential Throw or by coordinating the turns,
using the aileron and rudder controls simultaneously. (See Differential
Throw.)
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 modelers. 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.
Angle of Attack - The angle that the wing penetrates the air. As
the angle of attack increases so does lift and drag, up to a point.
ARF - A prefabricated model - Almost Ready to Fly.
ARR - Some cars and trucks are available virtually prebuilt and
will be indicated by the terms ARR (Almost-Ready-To-Run) or RTR
(Ready-To-Run). The ARR/RTR vehicles cost a little more, but if
you're just not interested in building your car, this is an option
for you. Most vehicles, however, come in kit form and require you
to do the building. This may require a few evenings, but the familiarity
you gain from assembly will make repairs, adjustments and modifications
easier to make down the road.
Battery Eliminator Circuitry (BEC) - A circuit that eliminates
the need for a receiver battery, usually in electric R/C cars and
boats.
BB - These letters usually designate a ball-bearing supported crankshaft
in an R/C engine. This makes the engine run smoother and last longer.
BRCA - The British Radio Car Association is the official UK organisation
for radio controlled car racing.
Buddy 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.
Boring Holes in the Sky - Having fun flying an R/C airplane, without
any predetermined flight pattern.
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 Styrofoam.
Carburetor - The part of the engine which controls the speed or
throttle setting and lean/rich mixture via setting of the needle
valve.
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.
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, usually supplied with
the radio if NiCd batteries are included.
Chicken Stick - A hand-held stick used to "flip start"
a model airplane engine.
Clunk - A weighted fuel pick-up used in a fuel tank to assure the
intake line is always in fuel.
Dead Stick - A term used to describe unpowered flight (glide) when
the engine quits running.
Differential Throw - Ailerons that are set up to deflect more in
the upward direction than downward are said to have Differential
Throw. The purpose is to counteract Adverse Yaw.
Dihedral - The V-shaped bend in the wing. Typically, more dihedral
causes more aerodynamic stability in an airplane, and causes the
rudder to control both the roll and yaw axis. This is why some trainers
and sailplanes require only 3 channels of radio control--i.e., having
no ailerons.
Direct Servo Control (DSC) - This radio feature permits you to
check servo operation without broadcasting a radio signal. A cable
connects the transmitter to the receiver. Direct servo control is
very useful for on-the-ground control checks.
Ding - Minor dent or damage to the structure. Also, a nick in a
prop. Dinged props must be replaced.
Down Thrust - Downward angle of the engine relative to the centerline
of the airplane. Down thrust helps overcome the normal climbing
tendency of flat bottom wings.
Electric Starter - A hand-held electric motor used for starting
a model airplane engine. Usually powered by a 12-volt battery.
Electronic Speed Control (ESC) - Electronic speed controls replace
the mechanical speed control and servo providing enhanced power
efficiency and precision in an electric R/C car or boat. In addition,
they are lighter which improves the performance of some electric
models.
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.
Endpoint Adjustment - This radio feature adjusts the length of
servo travel in one direction (a single channel will have adjustments
for two endpoints). If your plane rolls faster one way than the
other, endpoint adjustments can correct the problem.
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.
Field Charger - A fast battery charger designed to work from a
12-volt power source, such as a car battery.
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.
Four Stroke (Four Cycle) - Although a 4-stroke engine has less
power than a 2-stroke engine of comparable size, there are advantages
to 4-stroke engines. They do not require a muffler and are often
quieter than most 2-strokes are with a muffler. They can swing a
bigger prop than the same size 2-stroke engine. This is an asset
in the large, slow-flying aerobatic and scale models where 4-stroke
engines are usually mounted. Lastly, the fuel economy is better.
Frequency Control - Only certain frequencies are legal in the UK.
The most common for rc cars is 27mhz and 40mhz and for planes and
helicopters 35mhz and 40mhz.
Frequency Module - A frequency module plugs into the transmitter
and enables you to change the channel number your radio broadcasts
on.
Fuel Overflow Line (Vent) - The fuel line is either open to atmospheric
pressure or attaches to the muffler pressure nipple to pressurize
the fuel tank for better fuel flow to the engine. This is the line
through which the fuel will overflow when the tank is full.
Fuel Pick Up-Line - The fuel line in the fuel tank through which
fuel travels to the carburetor. Typically a flexible tube with a
weight or "Clunk" on the end which allows it to follow
the fuel with changes in aircraft attitude. This is the line through
which the tank is filled.
Fuselage - The body of an airplane.
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.)
Glow Plug Clip/Battery - A 1.2-volt battery, which is connected
to the glow plug on a model airplane engine for starting. The battery
is removed once the engine is running steadily.
Grease-In - A very smooth, gentle landing without a hint of a bounce.
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 Bar Plug - This type of glow plug has a "bar" across
the tip to help prevent raw fuel from being splashed onto the glow
element. Too much raw fuel will cool the plug and prevent it from
igniting the fuel/air mixture. An idle bar is a help in obtaining
a low idle speed.
Lateral Balance - The left-right or side-to-side balance of an
airplane. An airplane that is laterally balanced will track better
through loops and other maneuvers.
Leading Edge (LE) - The very front edge of the wing or stabilizer.
This is the edge that hits the air first.
mAh (Milliamp Hour) - A measure of a battery's total capacity.
The higher the number (ex. 600 mAh, 1,500 mAh) the more charge a
battery can hold and usually, the longer a battery will last under
a certain load. Typical rechargeable receiver battery packs are
in the 500-600 mAh range. Typical R/C car motor batteries are in
the 1,200 - 1,500 mAh range.
Mixing (Coupling) - Two radio control channels can be coupled together
so that they move together when only one control channel is activated.
Many 1/4 scale models require a combination of aileron and rudder
to turn. Mixing does this electronically at the transmitter. V-tailed
models, where the two halves of the V-tail must move not only together
but independently, are another use of control mixing.
Monster Truck - Monster trucks are gigantic! They are the king
of the hill in any group of R/C vehicles. Designed for torque instead
of speed, these car crushers can move up hills, down slopes and
over unsuspecting cars by virtue of sheer, brute power. The gas
powered monster trucks are nearly unstoppable.
Muffler - A device attached to the exhaust stack of the engine
to reduce noise and increase back pressure which helps low speed
performance. Note: Most R/C Clubs require the use of mufflers.
Muffler Baffle - A restrictor plate inside the muffler which reduces
engine noise. This plate can be removed to increase power, but only
if there are no noise restrictions where you fly.
Needle Valve - Adjustment on a carburetor used to set proper fuel/air
mixture. Some carburetors have separate needle adjustments for low
and high throttle. Typically, turning the needle clockwise (screwing
in) leans the mixture (less fuel), and vice versa. However, there
are a few exceptions--refer to the engine manufacturer's instructions.
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.
NiCd Starter - A self-contained battery and glow plug clip, used
when starting the engine. (See Glow Plug Clip.)
Off-Road Buggy - Off-road buggies are the most popular R/C land
vehicles. Available in gas or electric, these cars sport full-travel
suspensions, and high ground clearance. Their knobby rubber tires
give them the ability to tackle any dirt terrain. On a dirt track
or at the park, these off-road buggies are great fun.
One-Point Landing (or a figure 9) - Synonymous with "stuffing
it in." Something we hope you never do.
On-Road Car - On-road cars don't have the beefy suspension that
the off-road cars have, but they are impressive in their authentic
looks and all out speed. Built for racing on smooth, paved surfaces,
they are available in gas or electric, 1/10,1/12 and 1/8 scale.
It's easy to get involved. On-road cars are burning up the tracks
of organized parking lot racing courses everywhere.
Peak Charger - A peak charger automatically shuts off when your
battery is fully charged. This means longer run times for your vehicle.
Peak chargers are nearly foolproof, if you forget to turn it off,
the charger does it for you. No more overcharged batteries.
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.
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.
Programmable or Computer Radios - These high-tech radios are not
inexpensive but allow a full set of programmable transmitter features
like multiple plane memory, preprogrammed maneuvers (rolls, loops,
etc. at the touch of one button) and much more.
Prop Pitch - Props are designated by these two numbers, for instance
10 - 6. The first number is the prop's length, 10". The second
number is the pitch or angle of the blades. The 6 represents the
distance the propeller will move forward in one revolution, in this
case 6".
Re-Kitting Your Airplane - Changing your finished model back into
a kit, as a result of "stuffing it in."
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.
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.
ROAR - Radio Operated Auto Racing. National body to standardize
and sanction R/C car and truck racing.
RTF - Ready-to-Fly. Some newer airplanes are now available as RTF
models. These planes usually come with everything needed for flight--plane,
radio system, engine and all hardware. The really nice thing about
an RTF is that it will almost always be completely pre-built with
only a few minor construction steps left for the modeler. If you
want to fly and want to fly now, RTF is the way to go.
RTR - Some cars and trucks are available virtually prebuilt and
will be indicated by the terms ARR (Almost-Ready-To-Run) or RTR
(Ready-To-Run). The ARR/RTR vehicles cost a little more, but if
you're just not interested in building your car, this is an option
for you. Most vehicles, however, come in kit form and require you
to do the building. This may require a few evenings, but the familiarity
you gain from assembly will make repairs, adjustments and modifications
easier to make down the road.
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.
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 Output Arm - The removable arm or wheel which bolts to the
output shaft of a servo and connects to the pushrod.
Servo Reversing - This radio feature allows you to install the
servos where they can give the best pushrod routing without concern
about the direction of servo rotation. When your installation is
complete, turn on your radio and check each channel. If a channel
operates opposite of its intended direction, a simple flick of a
switch corrects the problem.
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. (See Flutter.)
Solo - Your first totally unassisted flight that results in a controlled
landing.
Spinner - The nose cone which covers the hub of the propeller.
Sport Airplane - A model which possesses some attributes of many
of the specialty airplanes and are best for general flying as they
are the most versatile and durable.
Stadium Truck - Designed for backyard fun, or all out racing, R/C
stadium trucks are the masters of "bump and jump" excitement.
Like full-size stadium trucks they are built to take punishment.
They have heavy-duty suspensions, oversized shocks and large tires
which enable them to survive the roughest terrain. Yet, when tuned
correctly, they also display speed and agility equal to the off-road
buggies.
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).
Tachometer - An optical sensor designed specifically to count light
impulses through a turning propeller and read out the engine RPM.
Tip Stall - The outboard end of one wing (the tip) stops developing
lift, causing the plane to roll suddenly in the direction of the
stalled wing. This situation is not fun when you are only a few
feet off the runway trying to land.
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 - This effective method of training allows two transmitters
to be connected by means of a trainer cord. The instructor can pass
control over to the student's transmitter so that he can fly. If
the student gets into trouble, the instructor can regain control
instantly.
Trailing Edge (TE) - The rearmost edge of the wing or stabilizer.
Transmitter (Tx) - The hand-held radio controller. This is the
unit that sends out the commands that you input.
Touch-And-Go - Landing and taking off without a pause. Often confused
with a good bounce.
2-Wheel-Drive vs. 4-Wheel Drive - As in full-scale cars, there
are two main drive types: two-wheel drive (2WD) where power is supplied
to the two rear wheels, and four-wheel drive (4WD) where power is
supplied to all four wheels. The 2WD vehicles are less expensive
and require less overall assembly and maintenance than 4WD vehicles.
Assembly and maintenance for 4WD vehicles tends to be more involved,
though not necessarily more difficult; the trade-off is that 4WD
vehicles offer better steering through turns.
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.
Wheel Collar - A small, round retaining device used to keep wheels
from sliding off an axle.
Wing - The main lifting surface of an airplane.
Wing Loading - This is the amount of weight per square foot that
has to be overcome to provide lift. It is normally expressed in
ounces per square foot. This specification can be easily calculated
as follows: If you know the square inches of the wing, simply divide
by 144 to obtain square feet. Divide the total weight (in ounces)
of the airplane by the wing area (in square feet). This information
is valuable when deciding on which airplane to build next. Planes
with high wing loading numbers must fly faster to stay in the air.
These are generally "performance" airplanes. Conversely,
planes with lower numbers do not need as much air flowing around
the wing to keep it flying. Gliders and trainer airplanes fall into
this category because slow, efficient flight is desirable.
Wing Root - The centerline of the wing, where the left and right
wing panels are joined.
Y-Harness - Two servos can be plugged into one channel with a Y-harness.
The two servos will then operate simultaneously. It is most often
used in areas where the strength of one servo is not adequate.
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.
Z-Bend - A simple Z-shaped bend in the wire end of a pushrod, which
is used to attach the pushrod to a servo output arm.
Z-Bend Pliers - An inexpensive plier type tool used for easily
making perfect Z-bends.
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