RC Airplane Terms A/Z

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.

ABN Aluminum-Brass-Nickel. The components used in the production of non-ringed engines. These engines use an aluminum piston, and a nickel plated brass sleeve. The engine is harder to turn over and start due to the tight fit between the piston and cylinder. This tight fit is what makes the engine more efficient, and powerful. ABN engines must be run in for best performance.

ABL Advanced Bimetallic Liner. Specialized form of ABN. Instead of a single-step, single-material plating, the ABL Plating process is based on a layered approach made possible by two OS-developed hard-nickel alloys. The first alloy is used as the bottom (bonding) layer, to fuse the top layer to the brass liner. The second alloy, developed for superior hardness, forms the top layer. Together, they create a barrier that protects the liner against excessive heat and wear.

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.

Aerobatics The act of performing 'acrobatic' or stunt manuevers in the air such as loops, rolls, etc.

After Run Oil A lubricant designed to displace unburned fuel in the engine after running. The fuel can accelerate corrosion on some engine parts. By using an after run oil, the fuel is displaced, and a protective coating lines sensitive engine parts. This is an inexpensive engine insurance, and promotes long engine life. There are several good after run oils on the market.

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.

ARC - Almost ready to cover.

ARF - A prefabricated model - Almost Ready to Fly.

Angle of Attack The amount of pitch at which an airfoil is flying. By adjusting the angle of attack, the efficiency of the wing/blade is effected. More precisely, the angle between the chord of an airfoil and the wind.

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.
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.

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.

Axis The line around which a body rotates.

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.

Barndoor Ailerons Larger, built up ailerons rather than an aileron from a simple strip of solid wood like some kits have.

Base Load Antenna A rigid, short antenna mounted to the model. Used to replace the longer receiver antenna.

Blade Strike Term describing the event of a propeller blade hitting another object. Although this can seem like a minor impact, the blades should be carefully and thoroughly inspected, as structural integrity is often compromised, producing an unsafe condition. If any question remains, do not fly until the blades are replaced.

Boring holes in the sky Having fun flying an R/C airplane, without any pre-determined flight pattern.Buddy Box Training method utilizing two transmitter control boxes, linked together. The trainer radio has override control, which the instructor uses to take control when the trainee looses control, or becomes disoriented.

Binding What occurs when the friction at a joint is stronger than the linkage.Blade Balancer Usually called a 'prop balancer' for aircraft. Used to ensure that the propeller and spinner are equally balanced side-to-side to avoid vibration problem

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.

CG Center of Gravity. A measurement used when balancing blades, as well as the model overall. Describes a central point in a given body, where all weight is considered to be concentrated. A central balance point.

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.

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.

Center of Pressure An imaginary point on the chord of an airfoil where the total of all aerodynamic forces are assumed to act.

Centrifugal Force he force created by a body's tendency to to follow a straight path working against a force which causes it to move in a curve, the resultant force which pulls away from a central axis of rotation.

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

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, usually supplied with the radio if NiCd batteries are included.

Chicken Stick - A hand-held stick used to "flip start" a model airplane engine.

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.

Clunk - A weighted fuel pick-up used in a fuel tank to assure the intake line is always in fuel.

Coning This effect is the bending of the rotor or propeller blades when stressed.

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 tailwheel.

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.

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 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.

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.

Disk Term describing the shape of the rotary wing or propeller formed by the spinning blades.

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.

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 Rates Radio function used to adjust control sensitivity.

Electric Starter - A hand-held electric motor used for starting a model airplane engine. Usually powered by a 12-volt battery.

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.

Empennage The vertical and horizontal tail surfaces of an airplane.

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.

Engine The methanol or gasoline fueled power plant used in a model. Two or four-stroke gasoline and glow engines are very popular in aircraft. Four-stroke engines tend to turn higher diameter lower pitch props, and therefore tend to be used in applications requiring more torque and less speed response.

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 This radio function allows the modeler to adjust the sensitivity of the control towards the center. This will make the small stick motions very precise, while longer stick movement moves the servo arm at a proportional rate.
FM Frequency Modulation. This describes the mode of transmission of radio signal from transmitter to receiver.

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.

Fin, Vertical Fin The fixed portion of the vertical tail surface.

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.

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 - The methanol/nitromethane/lubricant mix used to fuel model engines.

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.

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...."

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.

Gasser Slang for a model using a gasoline engine as a power plant.

Glow Fuel A Methanol based fuel, with a lubricating agent, used in most model engines. Most model fuels also use a percentage of nitromethane.

Ground Effect The cushion of air that the model rides on when close to the ground. This will decrease the amount of elevator needed to maintain a constant altitude when near the ground/landing

Gyro A mechanical or electronic device which helps to stabilize the orientation of the model by sensing rotation, and moving the appropriate servo to compensate. This device can be used on any axis, but is most frequently used on rudder and elevator, typically used to aid in 3D and precision flying.

Hanger Rash - The plane gets dings, dents and scratches from hanging around.

Hanger Queen - Stays in the hanger.

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.

Header Tank This is a small fuel tank used in line between the main tank and the carburetor. The purpose of the header tank is to ensure that the fuel fed to the carb is free of bubbles, which can be caused by foaming, or by the clunk falling away from fuel during complex maneuvers.

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. (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.

Horizontal Stabilizer The horizontal tail surface at the back of the fuselage which provides aerodynamic pitch stability to the airplane.

Hot Start An engine which has been running will tend to remain hot for a short time. During this period, it is possible to restart the engine by turning the crankshaft without the glow plug being plugged in to a glow starter. This is something to be aware of, as it could possibly create an unsafe condition.

Hover A 3D manuever. The art of flying without moving, also known as a 'hanger'. The aircraft is pointing straight upward, hanging solely on the thrust from the propeller. The model may be drifting horizontally with the wind but should not climb or dive.

Hydraulic Lock Hydraulic lock happens when the engine becomes flooded with fuel, to the point where the piston cannot compress it in the combustion chamber. This can result in engine damage if the crankshaft is forced through a rotation without relieving the pressure. To cure, remove the glow plug, and pour out the excess fuel.

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.

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 other's 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.

Incidence The angle of one portion of a model when compared to another portion of the model. For example, if the stabilizer is perfectly parallel to the ground and the leading edge of the wing points up 2 degrees when compared to the stabilizer, the wing has a 2 degree positive incidence when compared to the stabilizer. Up or down thrust angle are also called engine incidence. Having these 3 measurements in proper relation to one another affects how well the model flies, particularly on vertical lines. An improper engine-to-wing incidence often results in a model which cannot be trimmed on pitch because at higher throttle the engine is pulling the model upward and at lower throttle it is pulling the model downward, or vice versa.

Incidence Meter Used to measure the angle of attack of an airfoil.

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 "takesin".

Inverted Flying upside down. Note that elevator and rudder seem to work backward from the ground, as elevator, aileron and rudder inputs are all based upon the model's orientation (as if you were sitting inside).

Kit A Kit describes an unassembled model, arrives as packages of parts which must be assembled, as opposed to an ARF, or Almost Ready to Fly, which is mostly pre assembled.

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".

Landing Skid The rail type landing gear used on some models which have no wheels.

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.

Lean Refers to carburetor setting. When an engine is run too lean it will overheat, causing damage, and likely an in flight engine failure. Tuning a carburetor is best accomplished by starting rich, and working gradually to the condition which produces maximum power, while allowing a small amount of unburned fuel mixture to lubricate and cool the engine.

Lean Run This happens when an engine develops a lean condition. Possible causes are improper tuning, improper fuel choice, fuel foaming due to excessive vibration, or a leak developing in the fuel delivery system. The air in the fuel line will cause the engine to run lean.

LGLanding gear

Leading Edge (LE) - The very front edge of the wing or stabilizer. This is the edge that hits the air first.

Loading The load placed on the airfoil of a flying machine. In the case of an aircraft, this would be wing loading. Typically found by dividing the weight of the model by the total area of the main wing(s). Note that wing loading is only a good comparison between models of the same size. Larger models appear to have a far higher wing loading while displaying similar flight characteristics.

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.

Lubricant The agent used to aid in the reduction of friction between two parts. This term is used for many substances, which in turn are used in many different ways. They are all, however, used to reach the same objective, that being the reduction of wear between parts. In the case of engine fuel, the lubricant is added to the fuel at the factory in many cases. This might be castor, a synthetic, or a blend. The percentage of lubricant required in the fuel will depend on the type of fuel, the engine, and the model requirement.

M.A.A.C. - Model Aircraft Association of Canada. The official governing body for model aviation in Canada acting as a liason 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 competitve 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.

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.

Midrange The power band of an engine between idle and full throttle.

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.

Mixture Fuel to air mixture is determined by the needle valve on the engine carburetor.

Motor Any electric motor used in the model. Examples are the servo motors, which move the servo arms, and thus the control surfaces. There are also kits which use electric motors in place of the engine for quieter, cleaner flight.

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.

MPH Speed in Miles Per Hour. Like RPM, MPH is both singular and plural. You can go 1 MPH or 100 MPH. You don't go 100 MPH's.

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. 

Nose The front portion of a model's fuselage

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

One-Point Landing - Synonymous with "stuffing it in." Something we hope you never do.

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.

Pontoons See Floats.

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.

PCM Pulse Code Modulation. A modified FM signal used in high end radios. The signal is coded by the transmitter, resulting in a cleaner signal.

PPM Pulse Position Modulation. Another term for FM.

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 Balancer Device designed to aid in the balancing of model airplane propellers.

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".

Push-Pull A linkage set up using two rods. One rod pushes, while the other pulls.

Pull-Pull A linkage set up using two rods or wires. One is pulled for one direction, the other is pulled for the other.

Reflex If a wing has an airfoil that curves down from the high point, and then curves back up, it's said to be "reflexed". Reflex is the size of that reverse curve.

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.

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.

Retracts Short for retractable landing gear. Wheels and struts that fold up into the airplane to get them out of the airstream and present less resistance to the airflow.

Right Thrust Right yaw angle of the engine relative to the centerline of the airplane. Right thrust helps overcome the normal yaw tendency caused by the torque of the engine.

Ringed - An engine which uses a piston with a piston ring. Compare to ABC or ABN. Best used in dusty environments, a ringed engine is less susceptible to damage from contaminants in the fuel/air mixture, but does not provide the higher compression ratio of the ABC/ABN engines.

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.

RPM - Revolutions Per Minute. How fast something turns. It is both singular and plural. An engine can turn 1 RPM, or 10,000 RPM, NEVER 10,000 RPM's.

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.

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.

Rx Abbreviation for receiver.

Seaplane An airplane that has floats, or pontoons, attached to allow it to land on water.

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.

Simulator A computer program which uses a modified radio transmitter, and a graphic depiction of a model and flying area. This is used to give model pilots a feel for flying, without the risk of a crash. The simulator can be used by the newcomer to learn to take off/hover/forward flight/landings, or by the expert to dial in that new 3D routine without crashing a very expensive 3D model.

Skid The rail type landing gear used on many helicopter and some aircraft models.

Slats Moveable surfaces on the leading edge of the wing that help airflow in low-speed flight. They enable the wing to fly at lower airspeeds than without them by directing the airflow over the wing and preventing separation of the airflow. Basically, they are retractable slots. All modern jetliners have slats, which open when landing flaps are lowered. Some aircraft intended for very short takeoff and landing have slats that open and close automatically, depending upon airspeed and angle of attack.

Slip A maneuver where the airplane's controls are used to make the fuselage fly at an angle to the line of flight. This causes a tremendous increase in drag, and allows an airplane without landing flaps to increase its angle of descent without picking up a lot of speed.

Shot Down - A "hit" that results in a crash landing. Sometimes caused by radios miles away.

Slot A specially-shaped slot in the wing just behind the leading edge. This directs airflow from below to the top of the wing, and helps low-speed flight by delaying the stall. Because they are permanently-mounted, they do add drag. See also "Slats"

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.)

Snap Roll A type of rolling maneuver that is very quick and violent. It's basically a spin where the flight path is in any direction chosen by the pilot. Improper speed control during a landing approach can also make the model snap over on one wing and enter a spin. Since it's close to the ground, there's not enough room to recover, and a crash results

Solo - Your first totally unassisted flight that results in a controlled landing.

Slow Roll A very slow version of the roll.

Span, also "Wingspan" The widest straight-line distance between the two wingtips.

Spectrum Technology - A Transmiter/Reciver 2.4GHz systems that shifts every two milliseconds virtually eliminating signal conficts and interruptions unlike standered transmiters.

Speed Brakes Large panels that fold out of the aircraft structure to provide a lot of extra drag to the air. They are not part of the wing structure, but are usually mounted on the fuselage. Military jets most often have speed brakes, which fold out of the fuselage. Some airliners use spoilers as speed brakes when at altitude.

Spin A maneuver where at least one wing is stalled and the two wings are operating at very different angles of attack. This causes the airplane to rotate around its middle while it descends at a high rate of speed. When it's done on purpose, it is a precision maneuver, with the pilot trying to get the airplane to rotate an exact number of turns from entry to exit. When it's done accidentally, it can easily result in a crash. Many models crash when the pilot enters an accidental spin too close to the ground. This is caused by improper speed control during the landing approach.

Split-S Basically a reverse Immelmann. The airplane rolls onto its back, and then the nose comes down to finish a 1/2-loop. The direction of flight is changed 180°.

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.

Spoiler(s) Control surfaces on the wing that destroy lift. They "spoil" it. They are used on sail-planes because they can steepen the very flat glide of the aircraft, which makes landings much easier. On full-size aircraft, spoilers are also used to kill lift on landing to make sure the airplane is firmly on the ground. They also add a lot of drag to help with aerodynamic braking.

Stab Horizontal stabilizer, 'smaller wing'

Stabilizer A surface which increases the stability of a model. Most aircraft have two stabilizers, the horizontal (stab) and vertical (fin), which are mounted on the tail. The stabilizers help the model overcome the rotational forces caused by the engine.

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).

Strut Basically this is a supporting member. A wing strut supports the wing, and goes from the fuselage to the wing. Cabane struts are on biplanes, and support the upper wing over the fuselage. A landing gear strut is the portion that holds the wheel assembly to the airplane, and away from the wing or fuselage.

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.

Tail dragger The nickname of an airplane that sits on its tail with the two main wheels in front and a tail wheel in the rear.

Tailskid On old World War I type aircraft, or pioneer-type aircraft, there was no tail wheel. A wooden skid was used to support the tail of the airplane. While this helps slow the airplane during landing, it is useless as an aid to steering on the ground. The real aircraft with tailskids had to be maneuvered on the ground by ground crews, who put the tail on a small cart and towed the airplane where they wanted it. For small distances, the tail was picked-up by hand and the airplane pushed into position by the ground crew.

Tail wheel The small wheel at the tail of the airplane. This is found on the type of airplane that has the two large wheels in the front, and the small one in the rear. The airplane sits on its tail.

Throttle The control that allows the pilot to change the speed of the engine. In a car, the "gas pedal" is actually the throttle control for the car.

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.

Thrust The forward force provided by the airplane's engine. This is the force that drives the airplane forward.

TE Trailing edge (rear)

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.

TR Abbreviation for Torque Roll, a 3D manuever which begins as a hover and the torque of the engine/propeller rotates the model in a counterclockwise direction without any aileron (roll) inputs.

Torque The force which tends to cause rotation.

Touch-And-Go - Landing and taking off without a pause. Often confused with a good bounce.

Under camber This means that the lower surface of the wing has a hollow curve when observed from front to back. A thin wing with a high camber will be under cambered.

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.

Weathervane This describes the tendency to point into the wind. Stabilizers on a model result in its desire to weathervane.

Wheel Collar - A small, round retaining device used to keep wheels from sliding off an axle.

Wheel Pants The large fairings used to streamline the wheels of an aircraft that has non-retracting, or "fixed" landing gear (so-called because it's "fixed" in place).

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.

Windsock - This can be used to describe a number of devices, all of which give a visual clue to the direction and speed of wind in a given location.

Winglet - A small vertical surface at the tips of the wings. They help direct the turbulent airflow that all wings have at the tips. They makes the wings more efficient.

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.

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.

Yaw Rate - The rate of movement about the vertical axis of a model.

Z-Bend - A type of linkage point using a bend in the control rod which resemble a Z.

Zinger - Props.

If you know any others Slang please send to Rick@RickRCRacing.com
Please put Airplane Terms A-Z on the subject so I will know what it is.

 

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