Lake Sawyer HAWKS Glossary254 terms
| Term | Definition |
|---|---|
| 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. |
| Accelerated Stalls: | Occurs above the usual power-off stall speed when too much elevator control is input too quickly. This type of stall is usually far more violent than a wings-level, power-off stall. However, an airplane can be stalled at any speed if too much elevator is applied to fast. |
| 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.) |
| Aero Tow | The act of an aircraft hauling a glider aloft and releasing it. |
| Aero-elastic Flutter | (propeller) Is speculated to be a dominant mechanism causing rapid fatigue failure near a tip when insufficient or destabilizing tip stiffness exists. The interaction between variable loading and deflection induces a high frequency vibration with unpredictable magnitude. |
| Aft | Towards the rear. Used such as: "...with an aft center of gravity....". |
| Aileron Differential | Adverse yaw, especially on flat-bottom wings, is caused by the difference in airflow density between the bottom and top of the wing. The airflow along the wing’s bottom is denser than it is over the top of the wing. Therefore, the aileron moving down into this denser air creates more drag than the “up” aileron moving into the less dense airflow on top of the wing. The greater drag on just one side of the wing, the side with the down aileron, forces the wing, and the attached fuselage, to yaw in that direction. At slow airspeeds this yawing effect is more powerful, and happens faster, than the rolling effect caused by the ailerons. The airplane’s nose first swings away from the turn’s intended direction and only then begins to turn correctly once the roll begins. |
| Ailerons | Hinged control surface located at the trailing edge of each wing, that provides control of the airplane about the roll axis. Ailerons move in opposite directions in order to provide lift on one wing and "stall" on the other, in the process "rolling" the aircraft in the direction of the wing with the raised aileron. |
| Ailevators | Twin elevator servos plugged into separate channels used to control elevator with the option to also have the 2 elevator servos act as ailerons in conjunction with the primary ailerons. |
| Airfoil | The shape of the wing when looking at its profile. Usually a raindrop type shape. |
| Airware | Exclusive software developed by Spektrum for air RC transmitters that includes all programming functions and features. |
| 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. |
| Anhedral | Is the opposite of dihedral, having the wing tip centerline lower than the wing root centerline. Anhedral is generally used to aid in the instability of an aircraft to make it more aerobatic. Note that Anhedral is correctly measured as the vertical distance from the centerline of the root rib to the centerline of the wing tip. |
| ARF Bundle - Almost Ready to Fly | The TechOne ARF BUNDLE airplane requires intermediate level building skills. Some included components such as servos and motors do not come pre-installed and will need to be installed during the build process. Detailed building instructions are included with each model, however an adhesive product would be required such as a Foam Safe CA or FoamTac glue. |
| ARF Plus - Almost Ready to Fly | Freewing offers some of its 90mm jets in "ARF Plus" format. Expanding on the normal ARF format above, The ARF Plus format has ALL components installed already, EXCEPT for the motor, EDF unit, and ESC/UBEC. All other components, from the retracts to the servos and lights, are factory installed. The ARF Plus format allows pilots to obtain nearly ready-to-fly jets with most of the components installed, but gives those pilots the option of experimenting with installing their own custom power system, without the need of installing servos and doing the extensive plumbing of servo wires. |
| AS3X | A proprietary combination of gyros, sensors, and software that helps to stabilize and control the heading of RC aircraft models. |
| 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. |
| ATV | Adjustable Travel Volume. Used on many radio transmitters to limit, or extend, maximum throw of a servo. ATV can indicate having a single adjustment which affects both ends of the servo (known as AST) or one adjustment for each end of the servo throw (known as EPA). |
| AUW | All Up Weight - The total weight of the project. This includes everything needed to make it run or fly. Receiver, servos, batteries, etc. The all up weight of the project. |
| Auxiliary Channel | Any radio channel function other than the four basics (aileron, rudder, elevator and throttle). |
| AVC(Active Vehicle Control) | A proprietary combination of gyros, sensors, and software that helps to stabilize and control the heading of surface RC models. |
| Axial Roll | This type of roll is one where the aircraft’s fuselage remains exactly on the line of flight while the wings roll about it. Except for a very few jet fighters at high speed (the F-5 for one), no full size aircraft can perform a true axial roll. Most aircraft, especially trainers, roll about the line of flight, called a Barrel Roll. |
| 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. |
| 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. |
| Ballast | Extra weight added to a glider to help it penetrate better in windy weather or to increase its speed. Ballast is usually added in tubes in the inner portion of the wings or in the fuselage at the center of gravity. |
| Bank | This is a measure of how far from level flight a plane’s wings are set during a turn or maneuver. It is measured in degrees of angle from level flight. |
| Barn Door Ailerons | Larger, built up ailerons rather than an aileron from a simple strip of solid wood like some kits have. |
| Barrel Roll | This refers to an aerobatic maneuver that involves the airplane following the twist of a large imaginary corkscrew (horizontal) through the air by way of rolling the aircraft. |
| BB | These letters usually designate a ball-bearing supported crankshaft in an R/C engine or ball bearings in a better servo. This makes the engine run smoother and last longer. |
| BEC (battery eliminator circuit) | A feature of some speed control units that permits both the motor and the receiver to be powered by the same battery. |
| BHP | Brake horsepower. A measurement standard used by manufacturers to help consumers compare engines. NOTE: BHP is measured at the maximum operating RPM of the engine, which may not be the RPM level at which your engine will provide maximum life and consistent performance. |
| Binding Process | A proprietary combination of gyros, sensors, and software that helps to stabilize and control the heading of RC aircraft models. |
| Blind Nut: | (Also called a T-Nut) A pronged nut that is pulled into a surface such as wood so that it cannot turn when a bolt is tightened into it. Blind nuts are typically used in situations where it would be impractical to use a tool, such as pliers, to hold the nut while the fastener is being tightened. |
| BNF ("Bind And Fly") | Bind N' Fly airplanes/quads/helis already come with a receiver so all that is required is for you to bind the receiver to your radio. It is important to make sure that the receiver that comes with the model is compatible with your radio. For instance, if you have a Spektrum transmitter, only a Spektrum receiver will be able to bind it to an aircraft compatible with Spektrum receivers. Most radios and receivers are proprietary and only work together. Hobbico produces many "TXR" Transmitter Ready aircraft, which are essentially the convenience of a BNF since the pilot just needs to add their compatible Hobbico/Tactic brand radio. Horizon Hobby produces a wide lineup of aircraft sold in the BNF format under the sub-brands "Eflite" and "Parkzone". These aircraft are convenient additions to a pilot's fleet, eliminating the added cost of purchasing a new radio with each new aircraft. |
| Boundary Layer: | The thin layer of air immediately adjacent to a body moving through the air. |
| Brushless Motors | Brushless motors have almost completely replaced brushed motors in the RC industry. Their superior power and efficiency make them the obvious choice for powering your RC aircraft. Here’s what you need to know to use them, and some helpful info on how they work. Brushless Motor Benefits Before going into how brushless motors work, here’s why they’re useful: More Efficient – Brushless motors are much more efficient than conventional brushed motors. This efficiency has been measured to be between 85% to 95% better than brushed motors. Less electrical energy is wasted as heat, and more is used to do useful work. Reduced Noise – Brushless motors have fewer mechanical parts than brushed motors, so they emit less sound. Longer Lifetime – Fewer moving parts are in mechanical contact than in brushed motors, reducing wear. Reduced EM Interference – Brushless motors emit less energy as electromagnetic (EM) waves than brushed motors do. This contributes to their efficiency, and helps reduce radio interference. Torque, Voltage, And RPM Linearly Related – This means that the amount of torque or RPM produced by the motor divided by the voltage put in is a constant, making it easy to predict how much power you’re going to get. How Brushless Motors Work On a fundamental level, an electric motor’s only job is to convert electrical energy (like that provided by a battery) into mechanical energy, like the turning of a propeller or rotor blade. There are two basic facts that allow electric motors to work: Electric and Magnetic Fields are Related - That is, every moving charge produces a magnetic field, and magnetic fields can produce electric charge. Magnets Interact – Magnets will align when placed near to each other. All electric motors basically consist of two magnets. One of them is permanent, the other is a coil of wire that, when charged, becomes a magnet. The motor is designed such that the magnetic fields produced by each of the magnets are always out of alignment, causing the motor axil to rotate. This is similar to what happens when you hold a permanent magnet to a compass – the compass swings position so that it lines up with the magnets field. With the brushed motor design, the magnetic fields are kept out of alignment by turning on the different coils of wire that surround the motor axil in succession. Metal brushes make mechanical contact with the rotating axil and the contacts with each metal coil. As the axil rotates, the brushes contact different coils. The end result is that current flows through different coils at different times, constantly changing the magnetic field and rotating the motor shaft. It’s here that we see the main problem with the brushed design: the contact between the motor coils and the brushes causes friction, which increases with speed. The metal coils wear out over time, and are prone to sparking. They can also ionize surrounding air, creating ozone. So how can we get around these issues? The answer lies in the brushless motor design. Instead of using mechanical brushes to turn on the various wire coils, an ESC (electronic speed controller) is used instead. The ESC switches the motor coils on or off rapidly, and is synchronized to the motor axil position. Always look for an ESC with a capacity (measured in amps) greater than that of the motor you’re pairing it with. |
| 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 loses control or becomes disoriented. |
| Bulkhead | A vertical former inside a fuselage. |
| Butterfly | Also known as crow. A mix which activates up flaperons and down inner-most flaps for gliding speed control without spoilers or airbrakes. Crow (or butterfly) is only used for landing or perhaps for diving out of a thermal. |
| CA (cyanoacrylate): | A modern hobby adhesive that cures very quickly. |
| Cabane | A strut attaching a wing to the fuselage when the wing is above the fuselage such as biplanes and parasol aircraft. |
| 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 | An aircraft having the horizontal stabilizer forward of the main wing rather than in the conventional position behind it. Canard aircraft are theoretically more efficient because both the horizontal stabilizer and the wing provide upward lift. The horizontal stabilizer of a conventional aircraft provides downward lift to stabilize the aircraft resulting in an overall decrease of the aircraft's total lift. |
| Carburetor | The part of the engine which controls the speed or throttle setting and lean/rich mixture via setting of the needle valve. |
| Center of Gravity (CG) | The balance point of a model airplane. 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. |
| Center of Lift (COL) | The location on the top of the wing where the sum of all lifting forces is located. |
| Centrifugal loads | (propeller) are very predictable, given rotational speed and mass density distribution of a blade. Their contribution to total stress is relatively small. |
| CG | Center of Gravity. Describes a central point in a given body, where all weight is considered to be concentrated. A central balance point. |
| Chandelle | A very steep climbing turn where the airplane makes a 180° change of direction. |
| Channel | The number of functions your radio can control. Example: A 7-channel radio has 7 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. |
| 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. |
| Clevis | The Clevis is a small fastener at the end of a pushrod, usually made from nylon or metal, which connects the pushrod to the control horn. Clevises may frequently be referred to as links. |
| Collet | A slotted jaw that allows a limited range of bits to be placed in a tool such as a router, moto-tool, or pin vice. |
| Coning | This effect is the bending of the rotor or propeller blades when stressed. |
| Control Linkage | Any linkage transmitting servo movement to a control surface. |
| Control Surface | A movable surface such as elevator, rudder, and aileron. |
| Conventional Tail | A Conventional Tail is one with the stabilizer mounted directly on the fuselage and is the usual configuration of an aircraft. These are the simplest to construct and seem to be most popular. |
| Covering | The covering of an aircraft is the skin which is applied to the airframe, closing it in. On R/C aircraft, it is commonly a fabric or plastic film which is heat applied with an iron. Plastic covering, once applied, gives a durable, shiny finish and requires no further treatment. Fabric covering usually requires a layer of paint to finish it and make it resistant to the exhaust of the engine. Covering materials come on a roll and in many different colors and may be cut to rough shape before being ironed onto the airframe. |
| Cowl or Cowling | The large molded fairing around an engine. It serves two purposes: It helps the airflow go smoothly around the front of the airplane and also provides a proper path for cooling air around the engine. |
| Crab | When an aircraft flies at a sideways angle relative to the direction being traveled. Can be caused by a crosswind or may be flown intentionally to reduce altitude without increasing forward airspeed while on landing approach. |
| Crow | See "Butterfly". |
| Crucifix Tail | A stabilizer that is mounted partway up the fin. This is a compromise between the conventional tail and the T-tail, combining some of the major advantages of both. |
| Datum | (aka Datum Line) A reference line from which measurements are taken. |
| 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". |
| Decalage | The angular difference of the wing incidence and the horizontal stabilizer incidence. |
| Delta Wing | Delta Wing aircraft have one large wing with a sharply swept leading edge and a straight trailing edge. The result is a wing that looks like the Greek letter Delta (Δ). There is usually no horizontal stabilizer with conventional elevators. Delta Wing aircraft use their ailerons for both pitch and roll control. |
| Dethermalizer | A device used to spoil the trim of an aircraft and cause it to sink. A dethermalizer is most commonly used on free-flight endurance models to prevent them from flying away. |
| Detonation | Or pre-ignition is a potentially engine-damaging condition in which part of the fuel/air mixture ignites before the piston is at top dead center (TDC). Pre-ignition is a result of poor ignition timing and can be heard as 'engine knock'. In nitro engines, the proper combination of glow plug and nitro content will prevent this. |
| 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 upward inclination of an aircraft wing in relation to the lateral axis. A wing with dihedral is more stable and will tend to level itself from banked flight due to the higher wing having less lift than the lower wing. |
| Dipole | 3rd generation Frequency Hopping Spektrum 2.4 gHz protocol that offers superior radio frequency link security and the ability for over 100 systems to operate interference-free simultaneously. |
| 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. |
| Disk | Term describing the shape of the rotary wing or propeller formed by the spinning blades. |
| Doublers | A second piece of balsa or plywood added to the fuselage side to enhance strength. |
| Down Thrust | Downward angle of the engine relative to the centerline of the airplane. Down thrust helps overcome the normal climbing tendency caused by the torque of the engine. |
| Drag | Air resistance that slows the model. |
| DSM | Digital Spectrum Modulation; DSM is the 2.4GHz technology that makes Spektrum possible. |
| DSM2 | The second generation of Digital Spread Modulation. DSM2 offers significantly reduced latency and a faster response time than any brand of 27, 75, or 72MHz PCM system. |
| DSMR | Spektrum surface "Racing" protocol that delivers reduced latency, superior Radio Frequency link security, and the ability for over 100 systems to operate interference-free simultaneously. |
| DSMX | 3rd generation Frequency Hopping Spektrum 2.4 gHz protocol that offers superior radio frequency link security and the ability for over 100 systems to operate interference-free simultaneously. |
| DSSS | Direct Sequence Spread Spectrum. DSSS broadcasts on the 2.4GHz frequency band and generates a wide signal on a single frequency. |
| Dual Conversion | A dual conversion receiver filters the incoming radio signal from the transmitter through two separate and distinct electronic filters. This “double filtering” helps the receiver to ignore unwanted signals that are close to the frequency being used. This is NOT protection against another transmitter sending a signal on the SAME frequency. Instead, it is protection against other transmitters transmitting on frequencies that are close to the one being used. |
| Dual Link | Spektrum designed architecture that provides increased Radio Frequency link diversity. This combined with DSM2 is what makes the full range system possible. |
| 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 | The pitch-control surface. |
| 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. |
| 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. |
| ESC (electronic speed control) | The unit that controls the rpm of an electric motor. |
| Expanded Scale Voltmeter (ESV) | Device used to read the battery voltage of the on-board battery pack or transmitter battery pack under load. |
| Exponential(EXPO) | 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. |
| EZ Connector | A Dubro product name generically used to describe a fitting that is attached to a control horn or servo arm by means of a pin and a snap connector. A wire or cable pushrod slides through a hole in the connector and is secured by means of a set screw. (personally, I prefer the good ol' z bend) |
| Fades | The term used to describe data that does not reach the receiver. Dual Link minimizes this possibility. |
| Failsafe | A PCM function which moves servos to a pre-programmed position if transmitter signal is lost or corrupted. |
| Fairing | A component used to create a streamlined intersection between two or more other components or to cover a component to reduce drag. |
| FHSS | Frequency Hopping Spread Spectrum. These systems usually transmit a narrow band signal and rapidly jump through a fixed set of frequencies, spending a few milliseconds on each frequency. |
| Field Charger | A fast battery charger designed to work from a 12-volt power source, such as a car battery. |
| Figure 9 | A loop that is terminated by a dive into the ground. This maneuver is entertaining for all pilots present except the one who performs the maneuver. |
| 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 | A gradual increase in pitch angle to bleed off excess airspeed just before landing. |
| Flight Box | A special box used to hold and transport all equipment used at the flying field. |
| Flight Log | Flight Log is in reference to a screen that reports the signal and reception quality between your Spektrum Transmitter and telemetry capable receiver. This is reported to the user in real-time on compatible Spektrum transmitters. |
| Flight Modes | A function of your transmitter to change flight characteristics with the flip of a switch. This can be customized to control many aspects of flight, such as rates, control mixing and stability modes. |
| 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. |
| FM | Frequency Modulation. This describes the mode of transmission of radio signal from transmitter to receiver. |
| Forward Programming | Spektrum technology that allows the configuration of Smart devices (receivers, etc.) wirelessly and directly from the transmitter. No separate computer or mobile device is needed for setup and adjustments. |
| 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. |
| Frame Loss | The simultaneous loss of information to both antennas in the aircraft system. |
| Frame Rate | The time interval at which the servo data is updated on the receiver. |
| Frequency | The specific channel or Radio Frequency spectrum that a radio broadcast on. In a traditional RC radio, the transmission crystal resonates when voltage is applied; the rate of this resonation determines the frequency that is broadcast on. |
| 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. |
| Fuselage | The main body of the airplane. |
| Gain | Typically referred to in gyros, gain is the feedback correction authority used to counteract the rate of motions in a gyro. |
| Glide Ratio | Momentary radio problem that never happens unless you are over trees or a swamp ;) |
| Grease-In | A very smooth, gentle landing without a hint of a bounce. |
| 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. |
| GUID | Globally Unique Identification Code. Each individual module or radio is factory programmed with its own unique serial code. In the binding process, the receiver is programmed to only recognize the GUID code of one specific radio or module. |
| Half Cuban Eight | Model pulls up and executes five-eighths (5/8) inside loop to 45 degrees, hesitates, does one-half (1/2) roll, hesitates, then performs one-eight (1/8) inside loop back to level flight in the opposite direction as entry. |
| Half Reverse Cuban Eight | Model pulls up and executes one-eighth (1/8) inside loop to 45 degrees, hesitates, does one-half (1/2) roll, hesitates, then performs five-eights (5/8) inside loop back to level flight in the opposite direction as entry. |
| Hammerhead (stall turn) | Model executes one-quarter (1/4) loop to a vertical track, performs a stall turn through 180 degrees, then recovers with another one-quarter (1/4) loop to level flight in the opposite direction. |
| Hangar Rash | A skin condition suffered by your aircraft when it is not taxiing, flying or landing. I.E. when you are transporting it to the flying field, or working on it on your bench, or when someone steps on it accidentally. |
| Heading Hold | In gyros, used to maintain the indented heading or direction of the aircraft or vehicle despite outside influences, wind, round surfaces, etc. |
| 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. |
| Holds | In Spektrum systems, a hold occurs when 45 consecutive Frame losses occur. At this point the system enters failsafe. |
| Horizontal Stabilizer | The flight surface that supports the elevator and also helps to stabilize the model in pitch. |
| 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. |
| 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 | Angle of the airfoil's centerline to the longitudinal axis of the aircraft. Positive incidence indicates that the center of the leading edge is higher than the center of the trailing edge. Negative incidence indicates that the center of the leading edge of the wing is lower than the center of the trailing edge of the wing. |
| Incidence Meter | Used to measure the angle of attack of an airfoil. |
| 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 or a PNP Plug and Play. |
| Knife Edge | Model rolls 90 degrees at a uniform rate. The center of gravity is held at a constant altitude during the entire maneuver using rudder for altitude and elevator for rudder. |
| Kv Rating | The Kv number’s useful because it let’s you figure out how many volts you need to achieve a certain RPM, or vice versa. For an example, a 980 Kv motor powered by an 11.1 volt battery would spin at 980 x 11.1 = 10878 RPM with no load. The Kv rating always assumes no load on the motor, so the actual RPM that your achieve will be less than the one you calculate. |
| Laminar Flow Wing | Laminar Flow is the smooth, uninterrupted flow of air over the contour of the wings, fuselage, or other parts of an aircraft in flight. Laminar flow is most often found at the front of a streamlined body and is an important factor in flight. If the smooth flow of air is interrupted over a wing section, turbulence is created which results in a loss of lift and a high degree of drag. An airfoil designed for minimum drag and uninterrupted flow of the boundary layer is called a laminar airfoil. |
| Landing | The landing maneuver will start two (2) meters from the ground. The model flares smoothly to a nose-high attitude, dissipating flying speed, then smoothly touches the ground, within the landing zone, with the main wheels first, with no bouncing or changes in heading after touchdown. The nose wheel on a tricycle gear and the tail wheel on a conventional (unless a "three (3) point landing" of mains and tail wheel touching simultaneously is executed) should settle gently to the ground after a brief rollout. The maneuver shall be considered complete once the plane has slowed below flying speed and has rolled straight for 15 meters. |
| Latency | The time it takes for a servo or ESC to react to an input made on a radio. |
| 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 foremost edge of an airfoil or propeller, first part of the wing or propeller to go through the air. |
| Lift | The aerodynamic force generated by air flowing around an airfoil that is equal to or greater than the weight of the aircraft and acts opposite to the force of gravity. |
| Longeron | A load-bearing, fore-to-aft structural member of a fuselage. |
| mAh (Milliamp Hour) | A measure of a battery's total capacity. The higher the number (e.g., 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. |
| MHz | Megahertz. One hertz represents one cycle per second, and a megahertz is 1,000,000 hertz. |
| 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. |
| Model Memory | Internal memory or capacity available in the transmitters to store different aircraft settings and parameters. |
| ModelMatch | A safety feature that prevents a pilot from flying a model when the model selected in the radio is not correct. |
| Module MeMory | A device that plugs into the back of many radios that determines the broadcast frequency and band. |
| Moment (nose moment, tail moment) | Refers to a distance on a model forward or aft of the balance point. |
| Moment Arm | The distance between where a force is applied and the Center of Gravity. The distance from the Elevator hinge line to the Center of Gravity is the Pitch Moment Arm. |
| NiCd | Nickel Cadmium battery. Rechargeable batteries typically used as power for radio transmitters and receivers. |
| Nose | The front portion of a model's fuselage. |
| One-Point Landing (or a figure 9) | Synonymous with "stuffing it in." Something we hope you never do. |
| Oscillation | Back-and-forth movement similar to a vibration that may appear like a wobble. It may occur around any axis, roll, pitch or yaw. |
| Over-control | Excessive control inputs that overcompensate for unwanted model movement. |
| Packets | A set or group of data that is sent from an RC transmitter to a receiver in a digital radio system. |
| Panic Recovery | One of the most exciting features of SAFE receivers, Panic Recovery will automatically return the aircraft to level flight with the push of a button. |
| Parasitic Drag | A resisting force caused by external items mounted on an aircraft other than the lifting surfaces. |
| PCM | Pulse-code modulation (PCM) is a digital representation of an analog FM signal where the magnitude of the signal is sampled regularly at uniform intervals, then quantized to a series of symbols in a digital (usually binary) code. PCM hides small amounts of interference, which helps prevent unexpected aircraft movements during transient interference. However, small RFI issues may go unnoticed until they become significant. |
| Peak Charger | A charger that automatically shuts off when your battery is fully charged, ensuring longer run times and preventing overcharging. |
| Pitch | The angle of the aircraft in the up or down direction. |
| Pitch Axis | The airplane axis controlled by the elevator. Pitch movement involves raising or lowering the nose, affecting climb or dive control. |
| Platform | |
| Platform | The outline of a flight surface, such as an elliptical-shaped wing. |
| PNP | Plug And Play. Usually comes set up and ready to fly except for the receiver and transmitter. Some models may include both. |
| Polyhedral | A wing design with three distinct upward angles. The two wing halves form the first angle at the center, and additional angles occur closer to each wing tip. |
| Power Panel | A 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. |
| PowerSafe | An aircraft device (receiver) with dual battery redundancy to support high-current systems found in giant scale and turbine powered aircraft. |
| Preflight | A thorough check of an aircraft prior to flying to ensure airworthiness and safety. This includes checking all control surfaces, the propeller, spinner, landing gear, and more. |
| Priority | In Gyros Stick priority reduces the amount of gain as the control input (stick) is displaced from center. This gives more control authority as the limits of travel. |
| Prop Balancer | A tool used to ensure the propeller and spinner are equally balanced side-to-side, avoiding vibration problems. |
| Prop Pitch | The second number in a propeller designation, representing the distance the propeller will move forward in one revolution. |
| Raceware | Exclusive software developed by Spektrum for surface RC transmitters that includes all programming functions and features. |
| Range Test | An important aspect of RC flying success, the Range Check is a ground procedure to test the radio signal from your RC transmitter to the receiver to make sure it is strong and secure. We suggest a Range Check at the beginning of each flight session to confirm the system's operation. |
| Re-Kitting | Returning your finished model back into a kit, often due to a crash. |
| Receiver | The part of the radio system that converts signals sent by the transmitter into electrical impulses. |
| Reciever | A device mounted into an RC car or aircraft that receives and decodes a signal sent by a transmitter. Servos, ESC, and other devices are plugged into the receiver. |
| Reliakote | A water/ chemical resistance coating that is applied to the PC (electric) boards that make the electronics highly water resistant. |
| Remote Reciever | An auxiliary receiver that works in conjunction with a main receiver. These are beneficial in larger aircraft and aircraft that may have Radio Frequency blind spots caused by larger metallic objects such as engines, batteries, or carbon fiber. |
| Remote Reciever Protocol | The transmission “scheme” that each specific radio manufacturer designs for the brand. |
| Resolution | Refers to the incremental step size of the data transmitted to the receiver. |
| Resonance | The vibration frequency of rotating or moving parts. Excessive resonance can cause vibration damage. |
| Retracts | Short for retractable landing gear. Wheels and struts that fold up into the airplane to get them out of the air stream and present less resistance to the airflow. |
| RFI | Radio Frequency Interference. |
| Rib | The internal, vertical portion of the wing that gives it an airfoil-shaped contour. |
| 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. |
| Roll Coupling | Applying rudder alone can cause the aircraft to bank into a turn without aileron input. The ability of the rudder to perform a banked turn is called roll coupling since the rudder input also induces the roll into the bank. Roll coupling is caused by wing dihedral, (the upward bend in the wing), and rudder placement. The higher the rudder is above the wing and fuselage, the greater its roll coupling effect. Roll coupling in performance aerobatic aircraft is not a good thing as it makes certain maneuvers, like a slow roll or stall turn, very difficult. But it is good in an aerobatic trainer as it teaches the pilot how to coordinate rudder and aileron. |
| 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 | The vertical control surface that controls yaw. |
| Rx | Abbreviation for receiver. |
| SAFE | SAFE technology is an advanced flight assistance system that gives pilots the ability to fly without the worry of crashing due to common mistakes such as orientation loss or over-control. Built upon the successful Spektrum AS3X system, models with SAFE technology have multiple flight modes with progressive flight envelope limitations as well as self-leveling and flight stabilization. |
| Serv Sync | A resequencing of the data the radio transmits based on the type of mixing you select. This feature helps to sync control services that are connected (such as a swash plate on a helicopter) and is used in radios that have many channels. |
| Servo | An electromagnetic device that moves the control surfaces and is controlled by the electrical impulses from the receiver. |
| 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. |
| Sesquiplane | A biplane having one wing significantly smaller than the other. |
| Slat | A high-lift device on the leading edge of a wing designed to keep air flowing over the wing at a higher angle of attack than could be achieved otherwise. |
| 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. |
| 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.) |
| Slow Roll | Model rolls at a uniform rate through one (1) revolution in either direction. Center is the inverted portion of maneuver. Inside Loop: Model pulls up and executes the loop. The loop should be completely round. |
| Smart Technology | Designed and developed by Spektrum, Smart Technology employs the latest advancements in connectivity and integration for a hassle-free and more fun RC experience. This is made possible by an integrated microchip that transmits a vast amount of data to Spektrum chargers, ESCs, and transmitters. |
| 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. |
| Solo | Your first totally unassisted flight that results in a controlled landing. |
| 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. |
| Spinner | Cone on the front of the propeller made from plastic or metal to improve aerodynamics, looks, and use of an electric starter. |
| Split S | Model performs one-half (1/2) roll in level flight then immediately executes one-half inside loop to level flight in opposite direction as entry. (This is basically an Immelmann done backwards.) |
| 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°. |
| 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. |
| Sputter Bug | (Slang courtesy of RC Universe) A new Nitro owner running his engine too rich, causing all the excess fuel to either run down the fuselage or spill on the track. |
| SRXL | SRXL is a single wire serial data protocol developed by Spektrum that allows channel data from SRXL equipped receivers to be transmitted to flight controllers and other accessories. |
| SRXL2 | SRXL2 is a powerful bi-directional communications protocol that improves the speed, security, and richness of data transfer between your radio system and compatible on-board devices such as flight controllers and Smart ESCs. SRXL2 lowers the latency compared to legacy protocols and allows flight controllers to be configured directly from your Spektrum transmitter, without requiring a computer or smart device. You’ll also enjoy more responsive telemetry that can be customized precisely to your needs. And it’s all done over one signal wire! Please note that SRXL2 is not backward compatible with the legacy SRXL and remote receiver protocols. SRXL2 support updates may be required for your device to use SRXL2 receivers. |
| Stab | Horizontal stabilizer. |
| Stall | When the air flowing over the wing cannot produce enough lift to support the weight of the model. This can happen if the modeler flies too slowly, or if the wing is at a too-high angle to the incoming airflow. If the wing is at a too-high angle to the incoming airflow, then it cannot flow over the wing properly to develop lift. |
| Stall Turn | The maneuver in which the model is flown to a point where the rotor disk/main wing is vertical, reaches an apex/stalls, then is turned about the yaw axis to continue in a nose-forward/down attitude, and is then returned to horizontal flight. |
| Straight Flight | The model must be brought exactly parallel to the flight path and flown in an absolutely straight and level path. Inverted Flight: The model flies along a straight line inverted. |
| Sub-Trim | This is a trim function on many computer radios, allowing trim adjustments during setup while still allowing the full trim function in flight. |
| T-tail | Refers to a stabilizer that is mounted on top of the fin. This brings the stabilizer away from the turbulent airflow of the wing and makes pitch control more responsive. It also gets the stabilizer out of harm's way when landing on rough terrain. The T-tail construction is usually more fragile than the conventional tail and is more difficult to build. |
| Tail Dragger | This refers to the landing gear configuration where the main landing gear with two wheels is placed forward of the center of gravity and one small wheel, called a "tail wheel," is mounted under the tail of the aircraft. |
| 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. |
| Take off | The model must stand still on the ground with the engine(s) running, without being held. The throttle is then smoothly, not suddenly, advanced. After the takeoff roll has started, the nose wheel lifts off the ground (tail wheel for a conventional gear airplane), and the aircraft assumes a climb attitude while still rolling on its main wheels. When the aircraft reaches flying speed it should gently lift off the ground and climb at a gradual angle. The aircraft must not deviate in heading during the takeoff. The takeoff is completed when the model is approximately 2 meters (6 1/2 feet) from the ground. |
| TE | Trailing Edge (rear). |
| Telementry | Provides real time information regarding model parameters (like battery charge condition, speed, radio link condition, etc.) to the pilot or driver typically through the transmitter via on screen information, audio tone, or voice prompts. |
| Throttle Cut | Disables throttle function. |
| Thrust/Drag Loads | (Propeller) These are somewhat uncertain due to the complexities of aerodynamic environments. The relative axial speed at the propeller (at any radial station) is the aircraft speed plus the amount the air in front of the blade is accelerated by the mechanics creating thrust. The latter may be approximated using first-order classical theory. Much empirical lift/drag data (from wind tunnel tests) exists to quantify lift/drag loads once relative velocity and angle of attack distributions are established. |
| 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. |
| Torque | The force which tends to cause rotation. |
| Torsional Acceleration Loads | (Propeller) These are generally not known. Analytical estimating techniques used by Landing Products to quantify torsional acceleration loads suggest that they can become dominant when pre-ignition or detonation occurs. These observations are supported by test experience with very high-performance engines running at elevated temperatures. Such conditions cause high torsional loads (about the engine shaft) which create high bending stresses, adding to those from centrifugal force and lift/drag effects. These loads depend on unique conditions for specific engines, especially those "hopped up" for racing, where lean mixtures lead to high cylinder temperatures and pre-ignition/detonation. |
| Touch-And-Go | Landing and taking off without a pause. Often confused with a good bounce. |
| Trailing Edge (TE) | The aft-most edge of an airfoil or propeller. |
| Trainer Airplane | A model designed to be inherently stable and fly at low speeds, giving 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 they can fly. If the student gets into trouble, the instructor can regain control instantly. |
| Transmitter | The hand-held part of the radio system that sends the signal to the receiver. |
| Transmitter Binding | a 2.4GHz receiver needs to be 'bound' to the transmitter before it can receive signals from it. The process involves the Rx identifying a unique code being emitted from the Tx, and then the two components lock together on an available frequency. The process usually only takes a few seconds. Every flyer who binds a 2.4GHz radio and receiver are immediately given their own unique code that is as unique as a fingerprint. This ensures that the flyer will never have a conflict with any other flyer's code. Imagine 100 flyers all using 2.4GHz radios and receivers flying at the same time at the same field (must be a really big flying field!) without any interference. That's the beauty of 2.4GHz. |
| Tricycle Landing Gear | Refers to the landing gear configuration with a single steerable nose wheel mounted in front of the center of gravity and a set of main landing gear with two wheels positioned just behind the center of gravity. Tricycle landing gear is usually a little easier to use when learning. |
| Trim | The adjustment of a model's control surfaces to obtain a stable and balanced flight performance. |
| Vertical Fin | A fixed, vertical stabilizer that reduces the model's tendency to yaw about the vertical axis. |
| 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 | An aircraft's natural tendency to turn into the wind. |
| Wheel Collar | A small, round retaining device used to keep wheels from sliding off an axle. |
| Wi-Fi | Wireless technology that allows devices to exchange data. |
| Wind Sock | A tubular flag-like device that shows the direction of wind movement. Wind speed may also be approximated by the angle at which the sock hangs. Used by pilots to aid with takeoff, landing, and flight patterns. |
| Wing Chord | The distance measured horizontally between the wing's LE and TE. |
| 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. Trainers are designed to have low wing loading because slow, efficient flight is desired. |
| Wing Root | The centerline of the wing, where the left and right wing panels are joined. |
| Wireless Trainer | Allows wireless buddy box training using two transmitters (instructor and student) typically used to make training easier and safer. |
| X-Plus | Refers to the number of devices that you can connect into a receiver and control; also references the frequency a transmitter broadcast on. Utilizing the SRXL protocol, receivers with SRXL can utilize X-Plus to expand the number of allowed channel outputs with a X-Plus Expansion Module. These additional X-Plus Channels communicate at a slower rate and resolution (512ms compared to 1024ms) and are intended for non-control surface functions such as bomb drops, lights, winches, and retractable landing gear. |
| XBUS | Telemetry Module Protocol that allows for multiple sensors to communicate through one connection. This allows for each sensor to be plugged in from one sensor to the next, in a "Daisy-Chain" fashion. |
| 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 | The left or right movement of an aircraft's nose about its vertical axis. |
| 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 | Shaped like a “Z,” it is the simplest way to connect a pushrod to a control horn or servo-output arm./dd> |