Model Aircraft & Field Vernacular

Offered as help, particularly to those new to flying, in understanding the typical references which might be encountered down at the field.

ABC

Aluminium - Brass-Chrome. The components used in the production of non-ringed engines. These engines use an aluminium piston, and a chrome or 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. ABC engines must be run in for best performance.

ARF/ARTF

A prefabricated model - Almost Ready to Fly. Well, OK, so what does "almost" mean? Usually it will take anywhere from 30 minutes to five or six hours....or more if you are just starting. Surprisingly, some modellers actually like to build models...sometimes from "kits" which have some items pre-cut and contain some of the non-wood parts needed to finish the model.  Usually, however, none of the electronic items are included in an ARF except, perhaps, the motor...check the specs carefully before you purchase.

ACE

Arse Covering Exercise - ensuring that all eventualities are covered, might be played before accepting the 'Weekend Passout' See Pass Out

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)

After Run Oil

A lubricant designed to displace unburned fuel in the engine after running. The fuel can accelerate corrosion on some engine parts. By using an after run oil, the fuel is displaced, and a protective coating lines sensitive engine parts. This is an inexpensive engine insurance, and promotes long engine life. Marvel Mystery Air tool Oil is one of the best.

Angle of Attack (1)

The angle that the wing penetrates the air. As the angle of attack increases so does lift and drag, up to a point.

Angle of Attack (2)

This one has to be very carefully assessed before returning home, after you have called the wife or girlfriend on her mobile to organise a Covering (see 'Covering 2') only to find out that all of the time you were talking to her, she was actually sitting in her car by the field gate with you and the lads in full view - oops! Angle of attack could come as a bit of a surprise.

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.

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. It 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.

Buddy Lead

Lead connecting the instructor (master) and student (slave) transmitters together such that control can be switched by instructor to and from student as necessary

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.

CA (cyanoacrylate)

Commonly known as Super Glue.

Centre of gravity (C of G)

The balance point of a model airplane.

Clunk

Term used to describe the weighted end of the fuel pickup line in the fuel tank. The purpose of this is to ensure that the fuel pickup is always in the fuel supply, even when inverted.

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.

Covering (1)

This is the skin of the aircraft and is usually stretched over the airframe and wings prior to finally shrinking taught with a heat iron and gun - takes a little practice before achieving a perfect result.

Covering (2) see also Angle of Attack (2)

Taking far more practice than (1), this is where the member has arrived at the field for a session without any formal Pass Out, sometimes referred to as the Sneak Out and needs 'Covering'.

This usually takes the form of driving around the field whilst speaking to the wife or girlfriend on the mobile, explaining that you are driving to an unexpected call out on a job.

For realism during Covering, other club members should stop flying and drive around the field passing you now and again with engines revving and the occasional toot of the horn thus producing 'out on the road' sounds.

Tip for Novices at Covering - a pre-recorded CD of emergency vehicle sirens played at background volume can give extended flying time due to that road blockage which continues to delay your journey home or airport sounds when having gone to pick up that important customer.

Detonation

The ignition of the fuel air mixture before the piston reaches top dead centre.. not a good situation.

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 sweep angle of the wing panels which aids stability.

Disk

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

Doubler

A second piece of balsa or plywood added to the fuselage side to enhance strength.

Drag (1)

Air resistance that slows the model.

Drag (2)

Having to pack up early on a still sunny day to take the wife to buy a new outfit.

Elevator

Pitch-control surface.

Elevons

This is a feature used for example on Delta's where Elevators and Ailerons are combined and is usually programmable with computer radios.

ESC (electronic speed control)

The unit that controls the rpm of an electric motor.

Failsafe

Method where Servos are programmed to react in a particular way if radio interference is encountered, usually set when using PCM. One example would be to reduce Throttle to tick over to prevent a 'Flyaway'.

Flaperons

This is a feature provided on some computer radios whereby ailerons are programmed to operate in the normal way but are also programmed to act as Flaps when a particular switch is operated

Flare

A gradual increase in pitch angle to bleed off excess airspeed just before landing. 

Flutter (1)

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.

Flutter (2)

Heart state just prior to "Stuffing it in." or “Planting it” or after a ‘Glitch'

Fuselage

The main body of the airplane.

Glitch

Momentary radio problem that only ever happens over swamps, trees and other inaccessible places. Can be a cause of Flutter (2)

Glow Start

This is used to heat the element in a glow plug, and is used when starting the model engine. Can be self contained unit with own re-chargeable battery or connected by leads to a flight box.

Glow Plug

This is the plug that is used to ignite the fuel in a model engine. The combustion of the fuel in the engine keeps the element hot between cycles, thus the glow plug does not need to be regulated or powered while the engine is running

Gnats, A

Term applied to an extremely small measurement of distance or adjustment. Derived from the relative miniscule size of a Gnats testicle. A common form of usage might be, Jesus! only missed him by a Gnats then!

Greaser  

A very rare smooth, gentle landing without  so much as a bounce.

Ground Loop

An unwanted acrobatic manoeuvre while you plane is on the ground. The plane suddenly spins in a circle, sometimes tipping nose down...not good for propellers.

Hangar Rash

A skin condition suffered by your aircraft when it is not taxiing, flying or landing. i.e. when your are transporting it to the flying field, or working on it on your bench, or when someone steps on it accidentally.

Horizontal stabilizer

The flight surface that supports the elevator and also helps to stabilize the model in pitch.

Hot Start (1)

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.

Hot Start (2)

You get one of these at 4 in the afternoon when you realise that your Pass Out was only the half day type and you have been at the field since 8!!

Hydraulic Lock

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

Leading edge (LE)

The foremost edge of an airfoil or propeller, first part of the wing  or propeller to go thru the air

Li-Po

Rechargeable Lithium Cobalt Dioxide or Lithium Polymer Cell, usually pronounced ‘Ly Poe’

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.

Moment (nose moment, tail moment)

Refers to a distance on a model forward or aft of the balance point

Ni-Cd

Rechargeable Nickel Cadmium Cell, usually pronounced ‘Ny Cad’.

Ni-MH

Rechargeable Nickel Metal Hydride Cell, usually pronounced ‘ Ny My or ‘Nim’

Over-control

Excessive control inputs that overcompensate for unwanted model movement.

Pass Out

Usually obtained from the wife or girlfriend enabling a flyer to take to the field. Most common forms are the full or half day Pass Outs. Weekend Pass Outs are very rare and usually have some catch involved.

PCM / PPM

Pulse Code Modulation / Pulse Position Modulation

Piss Take or Taking the Piss

This is common practice at the field and usually follows the action of  (see Re-Kitting below). A Flyer must be well versed in this art form and be able to both take it and receive it when the occasion warrants such. Comes with experience.

Prop Pitch

Props are designated by these two numbers, for instance 10 - 6. The first number is the prop's length, 10". The second number is the pitch or angle of the blades. The 6 represents the theoretical distance the propeller will move forward in one revolution, in this case 6".

Receiver

The part of the radio system that converts radio signals sent by the transmitter into electrical impulses.

Re-Kitting

Reverting your finished model back into a kit, as a result of "Stuffing it in." or “Planting it” There is normally standard field procedure after such an occurrence - (see  Piss Take above)

Rib

The internal, vertical portion of the wing that gives it an airfoil-shaped contour

Rudder

The vertical control surface that controls yaw.

Servo

A motorised device that moves the control surfaces and is controlled by the electrical impulses from the receiver.

Stall (1)

The point at which the wing experiences a loss of lift; the aircraft will tend to drop abruptly.

Stall (2)

This Stall is probably the most difficult to master and must be well practiced as it is invaluable during questioning from the wife or girlfriend as to why Pass Out  terms seem to have been ignored, before a plausible answer is offered.

The Sneak Out

Crafty disappearance to the field without any form of Pass Out.

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.

Touch-and-Go (1)

Landing and taking off without a pause. Often confused with a good bounce.

Touch-and-Go (2)

That final quick caress with the wife or girlfriend (or boyfriend?) just before disappearing down the field to meet the lads with that new plane for the rest of the day.

Trainer Lead

See Buddy Lead

Trailing edge (TE)

The aft-most edge of an airfoil or propeller.

Transmitter

The hand-held part of the radio system that sends the signal to the receiver.

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.

Wing chord (chord)

The distance measured horizontally between the wing's LE and TE.

Wing Root

The centreline of the wing, where the left and right wing panels are joined.

Yaw

The left or right movement of an aircraft's nose about its vertical axis.

Z-bend

Shaped like a “Z,” it is the simplest way to connect a pushrod to a control horn or servo-output arm.