RC Glossary of Terms

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.

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.