Airplane/Helicopter Terms and Abbreviations

 

 

Airplane Terms

 

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.

3D

Term describing a type of flight pattern, which is characterized by the performance of very specialized aerobatic maneuvers below the model's normal stall speed. Examples include torque rolls, 'walk in the park', harriers, hangers, etc.

For Helis: combining two or more maneuvers into one maneuver. Examples: rolling circle, inverted backwards loop.

3F

Slang abbreviation for flip flop flying. Similar to 3D, but without the finesse.

AFR (Adjustable function rate/high rate)

Adjusts the total travel in each direction of a particular function, such as ailerons. For example, used to adjust total aileron travel whether ailerons are a single servo in channel 1, or two servos set up as flaperons, elevons, or other programming.

ATL

Low-side only trim adjustment. Throttle trims on most radio systems are ATL, allowing the trim to affect only the idle and not the high-speed engine's settings. NOR (normal) is the other option of trim setting wherein trim movement affects the servo across its entire range of motion.

ATV/EPA

Adjustable travel volume or end point adjustment. Adjusts the total travel in each direction of servos 1-8 regardless of their control assignment. For example, ATV adjustment to AIL channel will adjust only the servo plugged into channel 1 regardless of any flaperon, elevons, or other programming set-ups.

Aft

Towards the rear. Used such as: "...with an aft center of gravity...."

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 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.

Elevators

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.

Airbrake (Air only)

Combines elevator, flap, and optionally spoilers to suddenly slow the model for spot landings. May be triggered by throttle position.

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.

Amphibian

An aircraft that can fly off of water or land. The wheels retract into the hull or floats, depending upon the type of aircraft. An amphibian can land on water and then extend the landing gear to allow it to pull up onto the shore. Many seaplane bases had ramps to allow the airplanes to pull up onto dry land parking areas.

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).

Area

The number of square inches (or feet) of the wing. It's the wingspan multiplied by the wing's chord. The area of a tapered wing is the wingspan multiplied by the average chord.

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 wingspan divided by the chord. Aspect ratio is important where a wing's efficiency is concerned. A short aspect ratio (short wings) is better for maneuvering, since it allows a high roll rate. Short wings are also stronger than long wings. Gliders use high-aspect ratio wings (long, skinny wings) because they are more efficient for soaring flight. Example: 10 ft. wingspan with a 1 ft. chord has an aspect ratio of 10.

Auto Shut off

Safety feature which shuts off the transmitter after a set period of time of inactivity to avoid draining the transmitter battery. (Not all transmitters have this feature)

Autorotation

 

.4GHz – a.k.a. Spread Spectrum. The newest radio band available for R/C use. Operates at higher frequencies than noise. See also: FHSS and DMSS.

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.

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.

AMA - The Academy Of Model Aeronautics. The official national body for model aviation in the United States. AMA sanctions more than a thousand model competitions throughout the country each year, and certifies official model flying records on a national and international level.

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.

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.

DMSS – (Direct Sequence Spread Spectrum) — A 2.4GHz radio system which selects one (or two) of the available “free” frequencies and transmits only on the one(s) chosen. Like FHSS (Frequency Hopping Spread Spectrum) systems, it is resistant to electrical noise. See also: FHSS.

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 vs. Gas Cars - Electric vehicles are the most popular choice in R/C car racing. They are quick, quiet, easy to build and comfortable for the beginning R/Cer to drive. The electric cars are powered with a rechargeable NiCd battery that can be charged in as little as 15-20 minutes. A vehicle with a stock motor will provide about 6-8 minutes of run time; with a couple of batteries and a 15 minute charger, an electric car or truck is ready for hours of use. The popularity of Gas vehicles has increased tremendously over the last few years. The explosive power and acceleration of a gas powered car or truck is exciting to watch. Gas vehicles are powered by a small two-cycle engine burning glow fuel (not gasoline!), and many modelers enjoy the realistic sound and smell that goes along with gas powered racing. Some gas models can reach speeds over 50mph! The wider availability of pull-start engines and the new wave of 1/10 scale vehicles has made it much more affordable for the beginner to enter gas-powered racing.

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.

FHSS – (Frequency Hopping Spread Spectrum) — A 2.4GHz radio system which switches from one “free” frequency to another every few milliseconds. While jumping from one to the other frequency, you are not spending much time on that frequency and this keeps out interference. See also: DMSS.

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 - The FCC has allowed the 72MHz 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.

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.

LiIon Battery – Lithium Ion Battery. They are lighter in weight and have a much lower (5%) discharge rate than NiCds or NiMHs (30%).

LiPo Battery – Lithium Polymer Battery. Derived from Lithium Ion batteries, they’re compact and light, with the ability to offer 30% more power in less space than comparable NiCds and NiMHs. Must be used with a LiPo-compatible balancing charger.

M.A.A.C. - Model Aircraft Association of Canada. The official governing body for model aviation in Canada acting as a liaison to government agencies, such as Industry Canada (formerly Department of Communications) with regard to radio frequencies and their use in R/C models, as well as representing internationally competitive modelers to the Fédération Aéronautique International (FAI) through the Aero Club of Canada. M.A.A.C. also provides liability insurance to its members and chartered clubs, among many other membership benefits.

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.

Mode 1 / Mode 2 - Refers to the stick configuration of an aircraft transmitter's control sticks. Mode 1 has the aileron/throttle on the right stick and the rudder/elevator on the left. Mode 1 is popular in Europe and Asia. Mode 2 is the USA standard and has the elevator/aileron on the right stick and the rudder/throttle on the left. Almost all radios used in the USA, Canada, Central and South America are Mode 2. All 4-channel and above aircraft radios sold by Tower Hobbies are Mode 2 unless otherwise noted.

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 - Nitro methane, 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.)

NiMH Battery – Nickel Metal Hydride Battery. Rechargeable batteries which are typically used as power sources for cars, trucks and boats as well as receiver packs. They’re offer longer run times and are more environmentally friendly than NiCds.

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 is 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.

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.

 

 

RC Airplane terms

Engine – This is most often an internal combustion (IC) engine. Somewhat similar to your car or lawnmower engine in that fuel is burned inside a cylinder, which drives a piston, which turns a shaft. However, there are some very important differences, see here.

Motor – Sometimes used in place of “engine”. Also refers to the increasingly common electric motors used in place of the IC engine.

Nitro – Refers to fuel containing Nitro methane. Sometimes refers to just the nitro methane ingredient itself, as in: “this fuel contains 15% nitro”.

Glow Fuel – Same as nitro fuel. It’s called “glow” because the engine uses a glow plug instead of the spark plug found in gasoline engines.

Glow Plug – A heated element that causes the fuel to burn. The plug has a steady glow instead of an intermittent spark.

Battery – May refer to the power battery of an electric motor, or the battery for the radio receiver.

Receiver – Much like your car radio, the receiver gets radio waves sent through the air. These waves contain instructions for the servos that move the rc airplane's controls.

Transmitter – This is the box with joysticks that you hold, and use to send commands to the rc airplane.

Servo – Each servo is a small motor that is wired to the receiver. If given instructions to do so by the transmitter, the servo moves a certain amount, which also moves the aircraft control surface that is mechanically connected to it.

Servo arm – Connects the servo motor to the pushrod

Pushrod – Connects the servo arm to the control horn

Control Horn – Connects the pushrod to the control surface or device, e.g.: rudder, elevator, aileron, throttle, speed control

Rudder – The movable part at the back of the vertical fin. Causes the airplane to rotate left or right (yaw) about a vertical axis.

Elevator – The movable part at the back of the horizontal stab. Causes the airplane to rotate up or down (pitch) about a horizontal axis.

Aileron – The movable part at the back of the wing. Causes the airplane to roll left or right.

Vertical Fin – Part of the airplane’s tail piece. Stabilizes the aircraft against yawing motions.

Horizontal Stab – Part of the airplane’s tail piece. Stabilizes the aircraft against pitching motions.

Center of Gravity (CG) – The balance point of the plane. An unbalanced rc airplane will fly poorly and could crash.

Stall – Airplane flies too slowly for the wing to produce upward lift. The plane will start to fall from the sky. A bad stall near the ground is a common type of crash.

Spin – A stall combined with rotational motion. Could create a crash, or if done correctly, a fun aerobatic maneuver!

Propeller – Attached to the engine or motor, this creates thrust that pulls the aircraft forward.

Electronic Speed Control – On an electric rc airplane, device that regulates the battery voltage going to the motor. When the transmitter stick is moved, increases or decreases the motor and propeller speed, as well as the thrust.

Brushed Motor – A type of electric motor where current is supplied by a mechanical sliding contact.

Brushless Motor – A type of electric motor where current is supplied without a mechanical sliding contact. Tends to be more powerful, longer lasting, and more expensive than comparable brushed motors. Also requires a specialized controller.

Two-stroke – Type of internal combustion engine. The fuel is burned (power is supplied) on every second stroke of the piston. Most common and affordable type of rc engine.

Four-stroke – Type of internal combustion engine. The fuel is burned (power is supplied) on every fourth stroke of the piston. Quieter, more fuel efficient, but generally more expensive that comparable two-stroke.

 

Helicopter Terms

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 Bearing

Servo's output shaft is supported with bearings for increased performance and accuracy.

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.

Battery Fail-safe function

Determines how to regain throttle control after a receiver low battery warning.

Bell and Hiller

Control system used in helicopters. Changes pitch of blades in relation to their position via a swash plate. 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.

Brake flap mixing

A group of 3 mixes, mixing brake flap-to-elevator (F-E), aileron and speed flaps, all individually adjustable.

"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.

Butterfly-to-elevator mixing

4- and 5-servo gliders only. A preprogrammed mix to deploy elevator to compensate for ballooning caused by butterfly. Adjusted proportionally with the in-flight adjustment of butterfly.

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. Please refer to the swashplate FAQ for further information.

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.

Camber

If you draw a line through the center of the airfoil that's exactly half-way between the top and bottom surface, you get the mean airfoil line. Depending upon the airfoil, it can be straight or curved. This curve is called the "camber" of the airfoil. If it has a lot of curve, the airfoil is said to be "highly-cambered".

Canard

The horizontal surface forward of the wing used to control pitch. It's found on very few aircraft. Also the word used to describe aircraft that have a main wing and a horizontal control surface in the nose...also called, "tail first" aircraft.

CAMPac

Optional extended data storage module for certain Futaba transmitters.

Carburetor

The part of the engine which controls the speed or throttle setting and lean/rich mixture via setting of the needle valve.

Chandelle

A very steep climbing turn where the airplane makes a 180o change of direction.

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.

Channel delay (Servo Slow/speed)

A feature within ATV which slows servo operation any time the radio is in the particular condition which has the delay set.

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 NiCd batteries are included.

Chord

The "depth" of the wing, its distance from leading edge to trailing edge. One of the components used to determine wing area. May vary from root to tip.

Collective pitch (Air only)

Used to regulate variable pitch props to slow model and keep engine running in vertical dives and provide maximum torque in model's vertical climbs. Idle trim is used for how high the idle is when in reverse pitch (diving) and the pitch trim finely adjusts the amount of pitch at full throttle to avoid over-propping the engine.

Condition

Separate flight model which has nearly 100% adjustability separate from the basic model set-up.

Condition hold

Holds the actual output to the model in a predefined state, allowing the user to make adjustments to other conditions safely without having the model receive the commands for that condition. For example, condition hold is used by a heli pilot to keep the heli idling safely on the ground while adjustments are made to the throttle hold, idle-up, and inverted conditions. Condition hold is used by an aircraft pilot to keep the aircraft idling safely on the ground while adjustments are made to a condition which requires full throttle, retracts up, smoke on, or other equipment combinations which the modeler wants to adjust but not activate on the ground.

Condition Name

Used to name each flight condition to minimize confusion during set up and use.

Condition Select

Used to select and assign a flight condition to the model currently in use.

Control Surface

Any one of the various moveable portions of the wings, tail surfaces, or canard.

Conventional Gear

The landing gear arrangement where the airplane has a main gear and a tail wheel.

Copy condition

Used to copy one condition into another. Often used to duplicate a working base condition into additional conditions to minimize repeating set up steps.

Copy model

Used to duplicate the settings of one model already in memory into a second model memory. Often used to set up 2 similar models, or make a copy of a working model to experiment with new set-ups. Also used to copy models to/from a CAMPac data storage unit or a 32MB CF Card.

Coreless motor

In a conventional servo, the motor has a steel core armature wrapped in wire that spins inside the magnets. In a coreless design, the armature uses a thin wire mesh that forms a cup that spins around the outside of the magnet eliminating the heavy steel core. A coreless motor does not have magnets as standard servo motors do, so they have a smoother, more constant, and stronger action. Regular servo motors have either 3 or 5 magnets (poles) which when the armature is between these, the servo motor is at its weakest.

Cowl

The large molded fairing around an engine. It serves two purposes when done right: It helps the airflow go smoothly around the front of the airplane, and also provides a proper path for cooling air around the engine.

Cross-trim

Function set-up where the trimmer next to throttle adjusts elevator and the trimmer next to elevator adjusts throttle.

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

Slang term for a landing without engine power. An example: "I ran out of fuel at 50 feet and had to dead stick".

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.

Digital

Please see the digital servo web page: http://www.futabarc.com/servos/digitalservos.html

Diode

An electronic component which only allows current to flow one direction. Protects the transmitter against reverse polarity or power surges during charging.

Dorsal Fin

An extension of the vertical fin forward of the main part of the fin, and against the fuselage. On the top, or "dorsal" side of the aircraft.

Drag

The air resistance to forward motion. Drag can be increased with the use of certain types of devices installed on the aircraft, such as spoilers, airbrakes, or flaps. Old-style aircraft with lots of supporting wires had very large amounts of drag, while modern aircraft such as military jets, have very low drag.

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.

DualRates

A switch that can make controls more or less sensitive. Lower rates are better for beginners, who tend to over control.

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 trim (2- and 5-servo gliders only)

Two separate offset mixes for the elevator to allow pre-programmed elevator settings, for example, for thermal hunting, penetrating, gliding, etc.

Elevator-to-brake flap mix (5-servo gliders only)

This is a pre-programmed mix from elevator to the brake flaps (small centermost flaps) to increase lift for tighter turns, etc.

Elevator-to-speed flap mix (4-servo gliders only)

This is a pre-programmed mix from elevator to the speed flaps (primary flaps) to increase lift for tighter turns, etc.

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.

Elevon (Air only)

Used for delta wing and tailless aircraft which have 2 servos operating 2 aileron-like control surfaces as both elevator and aileron.

Empennage

The vertical and horizontal tail surfaces of an airplane.

Engine cut

Also known as throttle kill. Used to safely shut engine off.

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.

ExponentialRate

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.

FailSafe

A safety feature which turns a servo to a preset position if the signal is lost or interrupted. Please refer to the FAQ for more information. Additionally, battery fail-safe 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. Please refer to the FAQ for more information.

Fairing

A shaped area used to smooth out, streamline, or "fair", the joint between two members of an airplane. A wing fairing joins the wing and fuselage. A landing gear fairing streamlines the landing gear struts, and wheel fairings (wheel "pants") streamline the bulky shape of the wheels.

Field charger

A fast battery charger designed to work from a 12-volt power source, such as a car battery.

"Figure 9"

Can be an "official" competition maneuver, or a badly-done loop. When the model flies over the top of a loop and picks up too much speed, the momentum prevents it from maintaining a loop's round shape.

Fin, Vertical Fin

The fixed portion of the vertical tail surface.

Flap-to-elevator mixing (Air and 2-servo gliders only)

Used to counteract unwanted changes in pitch when flaps are deployed.

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.

Floats

Long, canoe-shaped structures that allow an airplane to land on water. They are not a part of the aircraft structure, but suspended below the fuselage on struts. Also called "Pontoons".

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.

Flyback

Decrease in angle held by a servo which is being commanded by an AVCS gyro when the input is released. For example, a rudder servo might be at full deflection when rudder input is held. When the rudder stick is released but the model has not yet turned as far as the AVCS gyro has read your input to tell it to move, the servo will continue to hold input. However, it may "flyback" or decrease the angle at which it is holding slightly. This is perfectly normal.

Flying Boat

The type of aircraft where the fuselage has the lower portion shaped like a power boat. The plane lands on water directly onto the fuselage. There may be small floats suspended from the wings to keep the plane level when it's in the water.

Fore, Forward

Towards the front. Used such as "...the forward edge of the rib...", or as in "...with fore and aft movement...."

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.)

Fuel mixture control

Used to command a second servo which adjusts the fuel mixture at the carburetor for different throttle position settings.

Function menu

Used to assign specific features to specific stick, switch, slider and knob positions. For example, flap control can be moved to a switch by simply changing function assignments.

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.

Grease-in

A very smooth, gentle landing without a hint of a bounce.

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.

Gyro sensitivity

Used to create stick priority or activate each rate of a dual rate gyro based on stick position. This preprogrammed mix decreases the gain of the gyro directly proportional to the amount of rudder stick given (or steps the gyro down from high to low rate on dual rate 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.

Hover

To maintain a stationary position in which the model is not climbing, diving, rolling or yawing.

Hovering offset (Heli programming only)

Adjusts the center point of the pitch curves, including the hovering pitch curve, to fine-tune the hovering point when it is not exactly center throttle stick position.

Hovering pitch (Heli programming only)

This is a pre-programmed hovering-type mix which gives an in-flight adjustment to the pitch curve at and around center stick (or the hovering point if that point is not at center throttle stick, then the center-point of this feature is adjusted with the hovering offset command) to give very fine-tuning for easiest hovering.

Idle Up

This is a setting on the transmitter which limits the throttle minimum. Particularly useful for FFF and 3D stunt flying.

Immelmann

A maneuver originally used to reverse direction in combat. The airplane noses up and over onto its back. It then rolls upright and continues in the direction opposite to the original direction. It was invented by the World War I German pilot Max Immelmann, whose airplane could perform the maneuver, and others couldn't. It got him out of a lot of trouble in combat until the Allied aircraft designs caught-up and allowed their planes to perform the maneuver, too.

Inhibit

Makes a feature inactive and unable to be used. When a function is inhibited, it cannot be used even if the assigned switch is moved to the on position. Setting a feature to INH turns off its functionality without losing any settings. Only visible in specific features.

Intake

An air inlet on an aircraft. You can have a carburetor intake, cooling intake, air conditioning intake (on full-size aircraft), and so on. Named because it "takes in" air, and because "intake" is a better-sounding word than "takes in".

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.

Landing Gear

The assemblies that include the wheels and the wheel struts. The word "gear" is used in the sense of "equipment", as opposed to the "toothed wheel" meaning of "gear". The British call the landing gear the "undercarriage".

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.

Linear Mix

Directly proportional.

Link

Instruction for one mix to obey another. Mixing function which allows multiple mixes to work in conjunction.

Lithium battery

The internal battery in the 9Z which maintains memory when the transmitter battery is removed.

Loop

A vertical circle in the air. The plane noses up, keeps rotating until it's on its back, and then comes down and around to describe a vertical circle in the air.

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.

MPH

Speed in Miles Per Hour. Like RPM, MPH is both singular and plural.

Main Gear

Also Main Landing Gear. The large, heavy-duty landing gear struts and wheels that support most of the weight of the airplane. They are usually under the wing or under the fuselage near the center of the aircraft. Any other landing gear struts and wheels are noticeably smaller.

Master Mix Mode

Mix option which causes slave channel to operate based on master channel's ATV, not AFR or D/R settings.

Metal gears

Drive gears within a servo which are made of one or multiple metal types. Metal gears tend to wear more rapidly than nylon gears when in the same installation, and so require more frequent service to maintain optimum accuracy; however, metal gears are more durable in the case of severe vibration, flutter, or physical shock.

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/replaceable 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.

Futaba module models include TP, TK, TJ, TL, and TK-FSS. For information on which module to use, see 9Z/8U modules, TF modules and aftermarket modules.

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. Specific list of Futaba narrow band transmitters.

NiCd = Nickel Cadmium battery

Rechargeable batteries which are typically used as power for radio transmitters and receivers.

Nitro = Nitro methane

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.

Nose Gear

The strut and wheel that's under the nose of some aircraft.

Null

Not assigned or never changed. For example, a mix which has a null switch assignment is always active no matter what switch is moved.

Nylon gears

Drive gears within a servo are made of nylon. Nylon gears show slower wear than metal gears, but are more prone to failure due to severe vibration, flutter, or physical shock to the servo.

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. Please refer to the PCM 1024 info page and the FAQ for more information.

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 to rudder (Heli programming only)

Also known as a revolution mix or a tail rotor mix, counters the torque caused by adding pitch with opposite direction rudder command to keep the helicopter from rotating or revolving as a result of the increased torque. Not required with the use of a heading-hold gyro, which self-counters the torque-caused movement.

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.

Programmable mix (Pmix)

Used to cause specific servo responses to specific inputs separate from the basic control set-ups. For example, used to mix 2 servos to operate in tandem to move a rudder on giant scale aircraft, or to mix smoke activation based upon throttle stick position.

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.

RPM

How fast something turns. It means Revolutions Per Minute. It is both singular and plural.

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.

Reflex