A Comprehensive Lexicon for Fixed-Wing Radio Control Airplanes
The world of radio-controlled (RC) fixed-wing aircraft encompasses a rich vocabulary that spans aerodynamics, engineering, electronics, and operational procedures. This comprehensive glossary serves as your definitive reference guide to understanding the technical language that defines our hobby. Whether you’re a newcomer trying to decode conversations at the flying field or an experienced pilot seeking precise terminology for technical discussions, this guide provides clear, accurate definitions rooted in both theoretical knowledge and practical application.
Each entry reflects current industry standards and regulatory frameworks specific to the United States, incorporating terminology from the Federal Aviation Administration (FAA), Academy of Model Aeronautics (AMA), and leading manufacturers. The definitions emphasize fixed-wing aircraft systems, excluding rotorcraft and multirotor applications to maintain focused clarity.
A
2.4 GHz – The frequency band used by modern “interference-free” RC radio systems. These spread-spectrum systems have largely replaced older MHz-band radios, virtually eliminating channel interference through advanced frequency hopping and direct sequence modulation techniques.
2-stroke (2-cycle) engine – A common type of internal combustion (IC) engine for model planes where the fuel/air mixture is drawn in, compressed, ignited, and exhausted in one piston cycle (single revolution). Two-stroke glow engines are popular for their exceptional power-to-weight ratio and responsive throttle characteristics.
3D – An advanced style of aerobatic flying characterized by maneuvers performed at or near the aircraft’s stall speed with extremely high angles of attack. True 3D aircraft feature oversized control surfaces with extreme deflection capabilities and thrust-to-weight ratios exceeding 1:1, enabling feats like hovering and torque-rolls.
4-stroke (4-cycle) engine – An IC engine design where the piston completes two revolutions (four strokes) to complete the intake, compression, combustion, and exhaust cycle. Four-stroke engines produce superior torque characteristics and more realistic sound profiles compared to 2-stroke engines, making them particularly suitable for scale models.
Academy of Model Aeronautics (AMA) – The largest model aviation organization in the United States, founded in 1936 with approximately 195,000 members. The AMA serves as the official national body for model aircraft flying and acts as a Community Based Organization (CBO) recognized by the FAA to provide safety guidelines for hobbyists.
Adverse yaw – The tendency for an aircraft’s nose to yaw opposite to the direction of an intended turn. This phenomenon occurs because the downward-deflected aileron creates more drag than the upward-deflected aileron, causing the nose to “skid” toward the outside of the turn. Pilots counter adverse yaw through coordinated rudder input or design features like aileron differential.
Aerobatics – Flight maneuvers not required for ordinary transportation, performed for entertainment, competition, or skill development. Examples include loops, rolls, spins, and inverted flight. Aircraft capable of performing a wide variety of aerobatic maneuvers are described as “fully aerobatic.”
Aeromodeling – The comprehensive hobby encompassing design, construction, and operation of scale or representative aircraft models. Aeromodeling practitioners, known as aeromodelers, engage in disciplines ranging from scale replication through innovative design exploration, contributing to both recreational enjoyment and aeronautical research advancement.
Aileron – Hinged control surfaces located on wing trailing edges, operating in differential pairs to control aircraft roll about the longitudinal axis. Aileron deflection creates asymmetric lift distribution across the wingspan, generating the rolling moments necessary for coordinated flight maneuvering.
Aileron differential – A control system configuration where ailerons deflect unequal amounts in opposite directions, typically with reduced downward deflection compared to upward movement. This arrangement decreases adverse yaw by reducing drag penalties from the down-going aileron while maintaining adequate roll authority.
Airfoil – The cross-sectional profile of wings, control surfaces, or other lift-generating components, designed to create specific pressure distributions as air flows around the shape. Airfoil selection fundamentally determines aircraft performance characteristics, including lift coefficient, drag properties, and stall behavior. Primary categories include flat-bottom (high lift, stability-focused), semi-symmetrical (balanced performance), symmetrical (aerobatic applications), and undercambered (maximum lift generation).
Airspeed – The velocity of aircraft relative to the surrounding air mass, distinct from ground speed due to wind effects. Airspeed determines aerodynamic force generation and represents the critical parameter for stall avoidance, optimal performance, and control authority maintenance.
Altitude – The vertical distance between aircraft and ground level, typically expressed in feet Above Ground Level (AGL) for RC operations. Under FAA regulations, recreational model aircraft are generally limited to 400 feet AGL in uncontrolled airspace, with specific requirements for operations in controlled airspace.
Angle of Attack (AOA) – The angle between the wing’s chord line and the relative wind direction. AOA is the primary determinant of lift generation, with increased angles producing more lift until the critical angle is reached, resulting in stall conditions.
Angle of Incidence – The fixed angle between the aircraft’s longitudinal axis and the wing chord line at the wing root, established during design and construction. This angle affects the aircraft’s natural flight attitude and trim characteristics.
ARF (Almost Ready to Fly) – A model aircraft kit requiring minimal assembly, typically involving wing attachment and radio installation. ARF models significantly reduce build time compared to traditional kits while requiring some hobbyist involvement in final setup and configuration.
AS3X Technology – Spektrum’s stabilization system that smooths out turbulence and gusty wind conditions through rapid, subtle control corrections. AS3X technology makes small aircraft handle with the stability characteristics of much larger models, particularly beneficial in challenging weather conditions.
Attitude – The aircraft’s orientation relative to the horizon, describing whether the nose is pitched up or down and whether the wings are banked left or right. Proper attitude control is fundamental to all flight maneuvers and phases.
B
Balsa wood – A lightweight, porous wood traditionally used in model aircraft construction due to its excellent strength-to-weight ratio. Balsa’s cellular structure provides both lightness and structural integrity, making it ideal for airframes, wing ribs, and internal framework components.
Barrel roll – An aerobatic maneuver where the aircraft follows a helical path, completing a 360-degree roll while maintaining forward motion and slight vertical displacement. Unlike an aileron roll, a barrel roll involves coordinated use of all controls to maintain positive G-forces throughout the maneuver.
BEC (Battery Eliminator Circuit) – A voltage regulation system, typically integrated into Electronic Speed Controllers, that provides stable power to receiver and servo systems from the main flight battery. BEC circuits eliminate the need for separate receiver batteries in electric aircraft configurations.
Bind-N-Fly (BNF) – A product format where aircraft come fully assembled with installed servos, motor, and receiver, requiring only transmitter binding for operation. BNF models provide immediate flight capability while allowing pilots to use their existing compatible transmitter systems.
Binding – The electronic pairing process between 2.4 GHz transmitters and receivers, establishing secure communication links and preventing interference from other radio systems. Binding procedures vary by manufacturer but typically involve specific button sequences or switch positions.
Brushless motor – Modern electric motor technology featuring electronic commutation rather than physical brushes, providing superior efficiency, power output, and longevity compared to brushed alternatives. Brushless motors require Electronic Speed Controller compatibility for proper operation.
Buddy box – A training system connecting instructor and student transmitters, allowing seamless control transfer during flight instruction. The instructor maintains override authority while enabling students to develop skills under supervised conditions, significantly improving training safety and effectiveness.
C
C-rating – A battery specification indicating maximum safe discharge rate as a multiple of capacity. For example, a 2200mAh battery with 20C rating can safely deliver 44 amps continuously. Higher C-ratings enable greater power output for demanding applications.
Center of Gravity (CG) – The aircraft’s balance point where weight is evenly distributed. Proper CG positioning is critical for stability and control, with forward CG providing stability at the cost of elevator authority, while aft CG increases maneuverability but reduces stability margins.
Channel – Individual control pathways in radio systems, each dedicated to specific aircraft functions. Modern transmitters typically provide 6-8+ channels, enabling control of throttle, elevator, rudder, ailerons, and auxiliary functions like flaps or retractable landing gear.
Clevis – U-shaped mechanical fasteners connecting pushrods to control horns or servo arms. Clevises are available in nylon (lightweight, non-conductive) and metal (high-strength) variants, with proper retention devices essential for safety.
Control horn – Lever arms attached to control surfaces providing mechanical advantage for servo-driven movement. Control horn positioning affects control throw and servo load, with closer mounting points providing greater precision and reduced servo stress.
Control linkage – The complete mechanical system transmitting servo motion to control surfaces, including pushrods, clevises, control horns, and servo arms. Proper linkage design ensures precise control response while minimizing play and mechanical failure risks.
Control surface – Movable aerodynamic surfaces enabling flight path control, including ailerons (roll), elevator (pitch), rudder (yaw), flaps (lift/drag), and spoilers (drag/lift reduction). Control surface effectiveness depends on size, deflection angles, and airflow conditions.
Cowling – Streamlined covering enclosing engines or motors, providing protection, aerodynamic efficiency, and cooling airflow direction. Scale models often feature detailed cowlings replicating full-size aircraft appearance and functionality.
D
Dead stick – Flight condition where propulsion has failed, requiring glided approach and landing. Dead stick scenarios test pilot skill in energy management and landing precision, making dead stick practice valuable for emergency preparation.
Dihedral – The upward V-angle of wings when viewed from the front, providing inherent lateral stability. Aircraft with significant dihedral naturally return to wings-level flight when disturbed, making them particularly suitable for training applications.
Disorientation – Loss of visual reference to aircraft attitude and direction, common when models are distant or silhouetted against sky. Disorientation prevention involves consistent flight patterns, distinctive color schemes, and maintaining reasonable distances.
Drag – Aerodynamic resistance opposing aircraft motion through air. Drag types include induced drag (byproduct of lift generation), parasitic drag (surface friction and form resistance), and interference drag (component interaction effects).
DSM/DSMX – Spektrum’s Digital Spectrum Modulation protocols for 2.4 GHz radio systems. DSMX represents the advanced frequency-hopping version providing enhanced interference resistance and connection reliability compared to earlier DSM2 technology.
Dual rates – Transmitter programming feature enabling multiple control sensitivity settings accessible via switches. High rates provide maximum control surface deflection for aerobatic maneuvers, while low rates offer reduced sensitivity for precise flight and landing approaches.
E
Electric starter – Handheld 12V motor device for starting internal combustion engines safely, eliminating hand-flipping risks. Electric starters feature rubber coupling cones engaging propeller spinners or nuts, providing consistent starting torque.
Elevator – Hinged control surface on the horizontal stabilizer controlling aircraft pitch attitude. Elevator input primarily affects airspeed in sustained flight, with throttle adjustments controlling altitude changes through energy management principles.
Elevon – Combined control surface incorporating both elevator and aileron functions, typically found on delta-wing or flying-wing designs lacking conventional tails. Elevons require transmitter mixing to coordinate pitch and roll control functions.
Engine mount – Structural assembly securing engines or motors to airframe bulkheads or firewalls. Proper mounting handles vibration and thrust loads while maintaining accurate thrust line alignment critical for flight characteristics.
EP (Electric Power) – Designation for battery-powered aircraft using electric motors rather than internal combustion engines. Electric power offers quiet operation, cleanliness, simplified maintenance, and instant throttle response compared to fuel engines.
ESC (Electronic Speed Controller) – Electronic device regulating electric motor speed based on throttle input from receivers. Modern ESCs incorporate multiple protection features including low-voltage cutoffs, thermal protection, programmable parameters, and integrated BEC systems.
Exponential (Expo) – Transmitter programming feature modifying control response curves around stick center positions. Positive expo reduces sensitivity near neutral for smoother control, while negative expo increases sensitivity for more aggressive response characteristics.
F
Failsafe – Safety system determining aircraft behavior upon radio signal loss. Programmable responses include throttle reduction, control surface positioning, or return-to-home sequences, preventing flyaways and uncontrolled crashes when communication fails.
Federal Aviation Administration (FAA) – U.S. government agency regulating airspace and aircraft operations, including recreational model aircraft. FAA rules govern registration requirements, altitude limits, airspace restrictions, and operational procedures for RC pilots.
Field box – Portable equipment container holding essential flying accessories and tools. Fuel pilots typically carry glow plugs, igniters, fuel pumps, and starters, while electric pilots include battery checkers, tools, spare propellers, and repair materials.
Fin – Fixed vertical stabilizer providing directional stability and preventing unwanted yawing motions. The rudder hinges to the fin’s trailing edge, combining to form the vertical tail assembly essential for coordinated flight.
Fixed-wing – Aircraft generating lift through stationary wings as opposed to rotary-wing helicopters or multirotor drones. This glossary focuses exclusively on fixed-wing RC aircraft, encompassing trainers, sport planes, scale models, and jets.
Flaps – Hinged surfaces on wing trailing edges that increase camber and surface area when deployed. Flaps generate additional lift and drag, enabling slower approach speeds and steeper descent angles beneficial for landing operations.
Flaperon – Aileron surfaces programmed to function as both ailerons (differential movement for roll control) and flaps (simultaneous downward deflection for increased lift and drag). Flaperons require transmitter mixing capabilities for proper operation.
Flare – Critical landing maneuver performed just before touchdown, involving power reduction and gentle up-elevator input to arrest descent rate and achieve smooth ground contact. Proper flare timing prevents hard landings and landing gear damage.
Flight pack – Main propulsion battery powering electric aircraft motors and (via BEC) radio systems. Flight pack selection affects aircraft performance, flight duration, and weight distribution critical for proper center of gravity positioning.
Foamie – Colloquial term for aircraft constructed primarily from foam materials including EPS, EPO, ELAPOR, and Depron. Foam planes offer lightweight construction, excellent crash resistance, and easy repair capabilities using appropriate adhesives.
FPV (First Person View) – Flight technique using onboard cameras and video transmission to pilot’s goggles or monitor, providing cockpit perspective. FPV operations require visual observers maintaining direct line-of-sight per AMA and FAA requirements.
Frequency – Radio communication channel designation. Historical MHz systems used crystal-controlled channels requiring careful coordination, while modern 2.4 GHz systems employ spread spectrum technology with automatic frequency management eliminating interference concerns.
Frequency control – Traditional club procedures preventing simultaneous use of identical frequencies through pegboard systems or frequency pins. Modern 2.4 GHz systems have largely eliminated frequency conflicts through advanced protocol design and automatic channel management.
Frequency hopping – Spread spectrum technique where transmitters and receivers rapidly switch among multiple frequencies according to predetermined patterns. This technology provides excellent interference resistance and enables multiple simultaneous operations without coordination requirements.
FRIA (FAA-Recognized Identification Area) – Designated locations where Remote ID requirements are waived for recreational model aircraft operations. Most AMA club fields qualify as FRIAs, simplifying regulatory compliance for traditional RC activities.
Fuel lock – Engine flooding condition where excess fuel prevents propeller rotation due to incompressible liquid in combustion chambers. Fuel lock typically results from over-priming and requires fuel removal via glow plug extraction before starting attempts.
Fuselage – Aircraft’s main structural body to which wings, tail surfaces, and landing gear attach. The fuselage houses radio equipment, batteries or fuel systems, and provides the primary load-bearing framework for all aircraft loads and stresses.
G
Glide ratio – The relationship between horizontal distance traveled and altitude lost during unpowered flight, expressing aircraft aerodynamic efficiency. Higher glide ratios indicate superior efficiency, with sailplanes achieving ratios exceeding 40:1 compared to typical trainer ratios of 8:1.
Glow fuel – Fuel mixture for glow plug engines consisting primarily of methanol (fuel), oil (lubrication), and nitromethane (power enhancement). Fuel composition ratios affect engine performance, with higher nitro percentages providing increased power at greater cost and complexity.
Glow plug – Heating element in glow engine combustion chambers, featuring platinum filaments that glow red-hot to ignite fuel/air mixtures. Glow plugs operate from battery-powered igniters during starting, then maintain combustion heat through catalytic reaction with methanol.
Go-around – Safety procedure aborting landing approaches when conditions become unsafe, involving immediate power application, pitch control for climb attitude, and return to traffic pattern for subsequent approach attempts. Go-around decisions prevent accidents from attempting to salvage poor approaches.
Ground effect – Aerodynamic phenomenon where aircraft flying very close to ground experience increased lift and reduced drag due to airflow interaction with surface. Ground effect becomes significant at altitudes less than wingspan and affects landing energy management.
Ground loop – Rapid, uncontrolled yawing motion during ground operations, particularly common with taildragger aircraft configurations. Ground loops result from center of gravity positioning behind main wheels, requiring proactive rudder control and proper approach techniques for prevention.
Ground speed – Aircraft velocity relative to ground surface, differing from airspeed due to wind effects. Ground speed affects landing approaches, with headwinds reducing ground speed and tailwinds increasing it, requiring approach adjustments for proper touchdown positioning.
Gyro – Electronic stabilization device providing automatic disturbance correction through rate sensors and servo feedback systems. Modern gyros offer programmable gain settings and multiple axis stabilization, significantly improving aircraft handling in turbulent conditions.
H
Hand launch – Takeoff method involving manual throwing of aircraft, typically used for models without landing gear or when operating from unprepared surfaces. Successful hand launches require proper technique, adequate airspeed, and immediate control input coordination.
High wing – Aircraft configuration with wings mounted above fuselage centerlines, providing inherent stability through pendulum effects. High-wing designs offer excellent ground clearance, stable flight characteristics, and simplified construction, making them popular for training aircraft.
Horizontal stabilizer – Fixed horizontal surface at aircraft rear providing longitudinal stability and elevator mounting structure. Horizontal stabilizer sizing and positioning significantly influence aircraft stability margins and control authority throughout the flight envelope.
I
IC (Internal Combustion) – Engine classification encompassing glow, gasoline, and diesel powerplants burning fuel/air mixtures for power generation. IC engines offer high power density and realistic operation but require fuel handling, maintenance, and noise considerations.
Incidence – Fixed angle between wing chord lines and aircraft longitudinal axis, established during construction. Wing incidence affects aircraft’s natural flight attitude, with typical trainers featuring slight positive incidence for stable cruise characteristics.
Induced drag – Drag component resulting from lift generation, where lifting surfaces create downwash and wingtip vortices that redirect some lift force rearward. Induced drag increases with angle of attack and decreases with airspeed, representing unavoidable cost of lift production.
Inrunner motor – Brushless motor configuration with internal rotating magnets surrounded by stationary windings, typically producing high RPM with lower torque. Inrunners excel in ducted fan applications or when coupled with reduction gearboxes for propeller drive.
J
Jet – Model aircraft powered by ducted fans (EDF) or miniature turbine engines, replicating full-scale jet aircraft appearance and performance characteristics. EDF jets offer electric convenience while turbine models provide ultimate realism at significantly higher complexity and cost.
L
LAANC (Low Altitude Authorization and Notification Capability) – FAA system providing automated airspace authorization for operations in controlled airspace, enabling RC pilots to obtain required permissions for flights near airports through smartphone applications or web interfaces.
Landing – Flight phase involving controlled descent and ground contact, representing one of the most challenging aspects of RC piloting. Successful landings require energy management, approach path control, and precise timing for flare execution.
Landing gear – Aircraft support systems including wheels, struts, and associated hardware enabling ground operations. Landing gear configurations include tricycle (nose wheel and two mains) and conventional (tailwheel) arrangements, each with distinct handling characteristics.
Leading edge – Forward edge of wings or control surfaces where air initially contacts the airfoil. Leading edge condition affects airflow attachment and stall characteristics, with modifications like slots or slats influencing performance boundaries.
Lift – Upward aerodynamic force generated by wings moving through air, opposing aircraft weight to enable flight. Lift production involves pressure differentials created by airfoil shapes and angles of attack, fundamental to all flight operations.
Li-Po (Lithium Polymer) – Advanced rechargeable battery technology offering high energy density, light weight, and excellent discharge characteristics for electric aircraft. Li-Po batteries require careful handling, specialized charging equipment, and safety precautions due to fire risks if damaged or mishandled.
Line of Sight (LOS) – Visual contact requirement where pilots maintain direct visual observation of aircraft throughout flight operations. LOS ensures situational awareness and regulatory compliance, with visual observers required for FPV operations.
Loop – Fundamental aerobatic maneuver involving vertical circular flight path, typically initiated from level flight with gradual elevator input to maintain consistent radius and G-loading throughout the maneuver.
M
Mixing – Transmitter programming feature combining multiple control functions to operate together when single inputs are made. Common applications include flaperons (aileron/flap combination), elevons (elevator/aileron), and crow (spoiler/flap coordination for glider landing approaches).
Mode 1/Mode 2 – Transmitter stick configuration standards determining which controls operate specific aircraft functions. Mode 2 (standard in USA) assigns throttle/rudder to left stick and elevator/aileron to right stick, with consistency critical for muscle memory development.
Motor mount – Structural component securing electric motors to aircraft frames, typically featuring cross-mounting or ring configurations. Proper motor mounting ensures thrust line alignment while handling vibration and operational loads throughout the flight envelope.
N
NiCd (Nickel-Cadmium) – Rechargeable battery technology known for durability, high discharge rates, and temperature tolerance, though largely superseded by NiMH and Li-Po alternatives. NiCd batteries suffer from memory effect requiring complete discharge cycles for optimal performance.
NiMH (Nickel-Metal Hydride) – Rechargeable battery technology offering improved capacity and reduced memory effect compared to NiCd, commonly used in transmitters and receiver systems. NiMH provides reliable power with simpler charging requirements than Li-Po systems.
Nitromethane – High-energy fuel additive enhancing glow engine power output, typically comprising 5-30% of fuel mixtures. Higher nitro percentages increase power and improve idle characteristics but raise fuel costs and engine operating temperatures.
O
Outrunner motor – Brushless motor design with external rotating case surrounding internal stationary windings, producing high torque at lower RPM ideal for direct propeller drive. Outrunner motors dominate park flyer and sport aircraft applications due to efficiency and simplicity.
P
Park flyer – Small, lightweight aircraft designed for operation in open park spaces, typically featuring electric power, modest performance, and damage-resistant construction. Park flyers enable urban flying while minimizing noise and safety concerns.
Pegboard – Traditional frequency control system using physical pins or markers to prevent multiple pilots from operating on identical channels. Pegboards have largely become historical artifacts with 2.4 GHz spread spectrum adoption.
Pitch – Aircraft attitude describing nose-up or nose-down orientation, controlled by elevator inputs. Pitch control affects airspeed in sustained flight, with climb/descent primarily controlled through throttle adjustments for energy management.
PNP (Plug-N-Play) – Product format providing complete aircraft with installed motor, servos, and electronics but requiring customer-supplied receiver and transmitter. PNP models offer flexibility in radio system selection while minimizing assembly requirements.
Power panel – Field equipment providing centralized 12V power distribution for glow engine support equipment including starters, fuel pumps, and glow drivers. Power panels simplify field operations while providing consistent power management for various engine support equipment.
Pre-flight checks – Systematic inspection procedures performed before each flight to verify aircraft airworthiness and system functionality. Comprehensive pre-flight checks represent the primary defense against preventable mechanical failures and unsafe conditions.
Proportional control – Radio system capability providing continuously variable control surface movement proportional to transmitter stick displacement, enabling precise flight control and smooth maneuvering. Proportional systems represent the standard for all hobby-grade RC equipment.
Propeller – Rotating airfoil system converting engine rotational power into thrust force, with blade design optimizing efficiency for specific aircraft and mission requirements. Propeller selection significantly affects aircraft performance across all flight phases.
Propeller adapter – Mechanical interface components securing propellers to electric motor shafts, available in various configurations including collet, bolt-on, and threaded designs. Proper adapter selection ensures secure propeller attachment while accommodating different motor and propeller combinations.
Pushrod – Rigid control linkage components transmitting servo motion to control surfaces, typically fabricated from steel wire, carbon fiber, or other stiff materials. Pushrod design affects control precision, weight, and system reliability.
Pusher configuration – Aircraft design with propellers positioned to push rather than pull aircraft through the air, offering advantages including improved forward visibility, reduced noise levels, and protection from propeller strikes during ground operations.
Q
Quarterly checks – Periodic comprehensive inspections examining aircraft structural integrity, engine condition, and system wear beyond daily pre-flight requirements. Quarterly maintenance identifies developing problems before they compromise safety or performance.
R
Radio – Common term for transmitter systems, representing the primary pilot interface with aircraft. Modern radios provide sophisticated programming capabilities, telemetry monitoring, and multiple model memory beyond basic control functions.
Range check – Pre-flight procedure testing radio system operational range and signal strength through reduced-power transmission and physical separation testing. Range checks verify adequate signal strength for planned operations while identifying potential interference sources.
RC (Radio Control) – Technical designation for model aircraft controlled via radio signals, distinguishing from free-flight or control-line alternatives. RC encompasses the complete system of transmitters, receivers, servos, and control linkages enabling remote aircraft operation.
Receiver (Rx) – Aircraft-mounted component receiving radio signals from transmitters and converting them into servo commands and ESC controls. Modern receivers incorporate multiple antennas, telemetry capabilities, and advanced signal processing for enhanced reliability.
Registration – FAA requirement for recreational aircraft exceeding 0.55 pounds, involving online registration and aircraft marking with unique identification numbers. Registration supports aircraft identification and pilot accountability in the National Airspace System.
Remote ID – FAA regulation requiring most drones and RC aircraft to broadcast identification information during flight, essentially creating digital license plates for aircraft operations. Remote ID aims to enable airspace monitoring and enhance safety through aircraft identification.
Retracts – Retractable landing gear systems folding into aircraft wings or fuselage during flight to reduce drag and improve scale appearance. Retract systems use electric, pneumatic, or servo-driven mechanisms for gear operation.
Roll – Aircraft rotation about the longitudinal (nose-to-tail) axis controlled by aileron deflection. Roll movements enable banking for coordinated turns and aerobatic maneuvers requiring precise control coordination.
RTF (Ready to Fly) – Complete aircraft packages including airframe, radio system, battery, and charger, requiring minimal assembly for immediate operation. RTF models provide entry-level convenience while incorporating all necessary components for flight.
Rudder – Vertical control surface hinged to the fin, controlling aircraft yaw (nose left/right movement). Rudder input coordinates with aileron control for efficient turns while providing directional control during ground operations.
S
SAFE Technology – Spektrum’s Sensor Assisted Flight Envelope system providing multiple flight modes with programmed limitations preventing extreme attitudes and control inputs. SAFE acts as an electronic safety net, particularly beneficial for training applications.
Scale – Aircraft modeled after full-size designs, with varying degrees of detail accuracy and proportion fidelity. Scale models range from semi-scale sport representations to competition-grade replicas with documented accuracy requirements.
Servo – Electromechanical device converting electrical signals into precise mechanical movement for control surface operation. Servo types include digital vs. analog processing, metal vs. plastic gears, and various torque ratings for different applications.
Servo arm – Output component transferring servo motion to control linkages, available in various lengths and configurations affecting control throw and mechanical advantage. Proper servo arm selection optimizes control response while managing servo loads.
Servo reversing – Transmitter programming feature changing servo rotation direction to correct improper control surface response without modifying physical linkages. Servo reversing simplifies installation while ensuring correct control surface movement.
Spinner – Streamlined cone covering propeller hubs to improve aerodynamic efficiency and appearance while providing safety enhancement by covering sharp propeller hardware. Spinners require proper balancing to prevent vibration issues.
Stall – Aerodynamic condition where wings exceed critical angle of attack, resulting in airflow separation and lift loss. Stall recovery involves reducing angle of attack (forward stick) and restoring airspeed before resuming normal flight attitudes.
Sub-trim – Transmitter feature enabling fine electronic adjustment of servo neutral positions without affecting trim lever settings. Sub-trim optimizes control surface alignment during initial setup while preserving trim authority for flight adjustments.
T
Taildragger – Aircraft with conventional landing gear featuring two main wheels and a tail wheel, providing lighter weight and better rough-field capability compared to tricycle configurations. Taildraggers require additional pilot skill due to ground handling characteristics but offer advantages for terrain operations.
Tailplane – Horizontal stabilizer providing longitudinal stability and elevator mounting surface. Tailplane sizing and positioning significantly influence aircraft stability and control characteristics throughout the flight envelope.
Tailwind – Wind component aligned with aircraft flight direction, increasing ground speed while potentially complicating landing approaches due to higher touchdown speeds. Pilots typically avoid tailwind landings when runway and wind conditions permit.
Thrust – Forward propulsive force generated by propeller or jet systems, opposing drag to maintain or increase airspeed. Thrust-to-weight ratios determine climb performance and vertical maneuver capabilities, with ratios exceeding 1:1 enabling 3D aerobatics.
Tractor configuration – Standard propeller arrangement at aircraft nose pulling the airframe through the air, contrasting with pusher configurations. Tractor designs offer advantages for engine cooling, maintenance access, and conventional aircraft appearance.
Trailing edge – Rear edge of wings or control surfaces where airflow rejoins after passing over upper and lower surfaces. Trailing edge condition affects boundary layer behavior and control surface effectiveness throughout the flight envelope.
Trainer – Aircraft designed for learning fundamental flying skills, featuring inherent stability, gentle handling characteristics, and damage tolerance. Trainers typically employ high-wing configurations with significant dihedral angles for self-leveling tendencies.
Transmitter (Tx) – Handheld controller sending radio signals to aircraft receiver systems. Modern transmitters incorporate computer programming, multiple model memory, telemetry display capabilities, and advanced mixing functions beyond basic control transmission.
Transmitter mode – Stick function assignments determining which controls operate specific aircraft functions. Mode selection affects muscle memory development and must remain consistent throughout training to prevent control confusion.
Trimming – Process of adjusting control neutral positions to achieve hands-off straight-and-level flight at desired cruise conditions. Proper trimming reduces pilot workload while providing reference points for recognizing required control inputs.
Tricycle gear – Landing gear configuration with steerable nose wheel and two main wheels aft of center of gravity. Tricycle gear provides stable ground handling characteristics preferred by many pilots, particularly during training phases.
TRUST – Required online safety test for recreational UAS pilots, covering basic airspace knowledge, operational procedures, and safety practices. TRUST certification must be completed and proof carried during flight operations as mandated by FAA regulations.
Tx – Standard abbreviation for transmitter in RC terminology and documentation.
U
UBEC (Universal Battery Eliminator Circuit) – Standalone voltage regulator providing receiver and servo power from main flight battery when ESC BEC capacity is insufficient. UBECs offer higher current capacity and improved reliability for demanding applications requiring multiple high-current servos.
Undercarriage – Alternative term for landing gear systems, more commonly used in British terminology but occasionally encountered in U.S. documentation and international product literature.
V
Vertical stabilizer – Fixed vertical surface providing directional stability and rudder mounting structure, essential for maintaining coordinated flight and preventing unwanted yaw excursions. Vertical stabilizer sizing affects both stability margins and control authority.
W
Wash-in – Wing twist where wingtips have higher angles of incidence than wing roots, potentially promoting tip stalling and increasing stall severity. Wash-in is generally avoided in design except for specific aerodynamic requirements.
Wash-out – Wing twist where wingtips have lower angles of incidence than wing roots, ensuring root sections stall before tips to maintain aileron effectiveness and gentle stall characteristics. Wash-out improves stall behavior and enhances safety margins.
Weathercocking – Ground handling phenomenon where crosswinds create yawing moments turning aircraft noses into wind direction. Weathercocking affects taxi operations and requires active rudder control for directional maintenance.
Weight – Downward gravitational force acting on aircraft, opposing lift for flight equilibrium. Weight distribution affects center of gravity positioning, critical for stability and control throughout the flight envelope.
Wing loading – Aircraft weight divided by total wing area, indicating lift requirements per unit wing surface. Lower wing loading enables slower flight speeds and gentler handling, while higher loading provides better penetration in turbulent conditions.
Wingspan – Maximum wing dimension from tip to tip, representing primary aircraft size measurement. Wingspan affects transportation requirements, field size needs, and performance characteristics including aspect ratio and wing loading calculations.
Y
Yaw – Aircraft rotation about the vertical axis controlled by rudder deflection, determining nose direction relative to flight path. Coordinated flight requires proper yaw control to prevent sideslipping during turns and maintain efficient flight paths.
Conclusion
This comprehensive terminology guide represents the essential vocabulary for understanding and participating in the fixed-wing RC aircraft hobby. Mastery of these terms enables effective communication with fellow enthusiasts, precise technical discussions, and deeper appreciation of the engineering principles underlying our aircraft.
The hobby continues evolving with advancing technology, regularly introducing new terminology while older concepts become historical references. This guide reflects current U.S. standards and practices, providing the foundation for continued learning and skill development in this rewarding pursuit.
Whether you’re decoding conversations at the flying field, researching aircraft specifications, or troubleshooting technical issues, this reference guide supports your journey toward greater understanding and enjoyment of radio-controlled aviation.
Safe flying and happy landings!