Glossary of Aeromodelling Terms
his fantastic, sociable and enthralling hobby of ours has a language
all of it's own, below you will find the majority of terms often
talked about, If I've left one out, please E-mail
me and I'll include it.
A | B | C
| D | E | F |
G | H | I | J
| K | L | M
N | O | P | Q
| R | S | T |
U | V | W | X
| Y | Z
Term describing style of flying which is characterised by the performance
of very specialised aerobatic manoeuvres below the model's normal
stall speed. Examples include torque rolls, 'walk in the park',
harriers, hangers, etc.
Slang abbreviation for flip flop flying. Similar to 3D, but without
the finesse.
Number describing degrees in an arc. A 360 represents one full
turn through an axis. A 360 turn, for example, is a flat turn where
the aircraft does not roll its wings but rather just 'slides' through
360 degrees turning on rudder only.
82 deciBell (Average) This is the maximum
recommed noise level measured with a sound meter at 7m from the
engine at full throttle see 'How
to Noise Test a Model Aircraft (The BMFA way)' Noise is measured
on a logarithmic scale (I bet when you were in school you thought
you'd never use log scales in 'real life') so a reduction of 3dB(A)
is roughly half the noise!
These letters are used to describe the type of piston and cylinder
used in some engines. Aluminium piston. Brass cylinder
liner. Chrome coating on the surface of the brass cylinder
liner.
A type of plastic often used for vacuum formed components such
as cowlings.
American version of ARTF
ARTF = Almost Ready To Fly (back
to top)
A Kit where most of the hard and time consuming work has been done
in the factory. All of the building and covering of the fuselage,
wings and tail plane are done for you, all that is left to be done
is join the wings, glue in the tail assembly, install the engine,
and radio equipment. This type of kit is becoming very popular and
the quality is improving all the time. Having said that I still
find ARTF kits with the wrong incidence set on either the wing or
the tail plane.
ARTC = Almost Ready To Cover (back
to top)
A Kit where most of the wood work has been done in the factory.
Most of the building of the fuselage, wings and tail plane are done.
You have to cover all parts, join the wings, glue in the tail assembly,
install the engine, and radio equipment. This is a good type of
kit as you have a lot of the long and tedious work done for you,
but you have the choice of making your model aircraft stand out
by applying some snazzy colour scheme. This type of kit is not very
popular, most people want the speed and convenience or ARTF kits.
ATL = Adjustable Throttle Limiter (back
to top)
High-end feature which adjusts to bring full servo potential within
the limits of bind-free servo travel. Ideal for throttle control,
or for more effective braking in gas racing.
ATV/EPA = Adjustable Travel Volume/End Point Adjustment (back
to top)
Allows separate adjustments of maximum servo travel to both sides
of neutral. Helps tailor outputs for different control styles.
The BMFA operate a scheme where you are tested to show your level
of skill in flying a model aircraft. The first level is known as
an 'A Certificate'. To take the test is free and generally someone
in your club will hold an 'Examiners Certificate' so talk to them
and ask them what is involved in obtaining an 'A Cert.' Most reputable
clubs insist that learners are supervised by and experienced pilot
with an 'A Certificate' or greater. An 'A Cert.' is relatively easy
to get and just shows you have basic control over your model aircraft
and that you are not a danger to people or property.
A turn in the direction opposite to that introduced by the ailerons,
caused by the drag of the down-going aileron exceeding the turning
moment introduced by the up-going aileron.
A general term to describe a type of aircraft and/or a style of
flying that incorporates any manoeuvre that would not be used by
a full sized aircraft in normal flying.
The cross-section shape of a wing taken at right angles to the
wing span., Also known as the wing section or rib section.
'After Run' is a special oil that should be used in your engine
after you have finished flying for the day. It is specially designed
to protect your expensive engine from rust and corrosion. It is
essential you use 'after run' when using fuel with a high 'nitro'
content as nitro causes corrosion. With the engine stopped open
the carburettor of your engine and drop some (see bottle for recommended
amount) after run down into the carb, and flick the engine over
6-10 times to ensure the after run covers the inside of the engine.
See 'caring for your engine'
Because the downward travel of the aileron causes more drag then
the up travel, sometimes it is necessary to have a lower amount
of travel in the downward direction compared to the upward direction.
The differential can be set up either mechanically of electronically
in a programmable computer transmitter. The extra drag of the downward
moving aileron can in some aircraft cause a 'yaw' effect making
rolls look untidy, by reducing the downward travel you will get
better looking more axial rolls from your aircraft.
Hinged control surfaces located on the trailing edge of the wing,
one on each side, which provide control of the aircraft about the
roll axis. The control direction is often confusing to first time
modeller For a right roll or turn, the right hand aileron is moved
upward and the left hand aileron downward, and vice versa for a
left roll or turn.
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.
An aerodynamic control which can be extended to increase drag and
slow down an aircraft. Often used on model aircraft to control/increase
descent rates. On some aircraft the air brakes are used in conjunction
with the ailerons for lateral control at low speeds where the ailerons
become ineffective.
The shape of the wing when looking at its profile. Usually either
flat bottomed or symmetrical
The time spent actually flying your model aircraft.
Horizontal tail surfaces which do not have a separate elevator.
The whole surface moves as one to give pitch control.
A device for measuring wind speed.
Angle of the wing chord line in relation to the longitudinal axis
of the fuselage. This should not be confused with the "Angle of
Attack".
The angle that the wing penetrates the air. As the angle of attack
increases so does lift, up to a point (and drag) if the angle of
attack is too high the plane stalls.
The ratio of the wingspan to the wing's chord (depth). For gliders
this number will be larger than sport planes, which will generally
be larger than a 'jet' style aircraft.
An aircraft that flies by the lift generated by free wheeling rotating
wings set 'windmill' fashion above the fuselage. The forward motion
of the autogiro provides the force to keep the rotors turning so
unlike a helicopter an autogiro cannot hover.
BEC = Battery Eliminator Circuitry (back
to top)
Allows receiver to draw power from a main battery pack, eliminating
the need for (and weight of) a receiver battery.
To save the aircraft from loosing control and crashing, when at
the end of the flight the voltage of the battery falls to a set
level the BEC cuts the power to the motor but still supplies power
to the receiver and servo's allowing the aircraft to be brought
in for a 'dead stick' landing. This feature is only found in ESC's
(Electronic Speed Controllers) which are used to control the speed
of electric motors.
Connection using a ball, and a link which rotates on the ball.
Used to connect the servo to a control surface or lever. These are
more resistant to wear then a standard 'clevice' and are 'slop'
free
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.
Balsa wood comes from the West Indian Corkwood tree (Ochroma lagapus).
It is used in the construction of model aircraft as it is a very
light and easily cut and formed. When selecting balsa wood it is
important to consider the intended application as it varies considerably
in density and hardness.
Connection using a ball, and a link which rotates on the ball.
Used to connect the servo to a control surface or lever.
A short rigid, aerial mounted to the model. Used to replace the
longer standard receiver aerial.
A battery checker is a small electronic device that has a row
of green, amber and red LED's on it. It is used to check the condition
of the battery that is used to power the receiver and servo's. You
need the read the manufactures instruction very carefully so you
understand fully what it is indicating. It is best to fit a battery
checker onboard and get used to checking it regularly. The reason
why it is best to fit one on your aircraft as opposed to using an
external one is that the voltage of the battery falls slightly when
put under load (i.e. when the servo's are working) and this gives
you a much better idea to the condition of the battery. A battery
can read 'OK' when the receiver is not switched on and no servo's
connected, but can read 'low' when every thing is connected, switched
on and all servo's are moving, in this condition DON'T fly, recharge
your receiver battery. I highly recommend that you fit an onboard
battery checker on all your models., Is the destruction of your
pride and joy and the loss of all that money not worth an extra
tenner?
The pivoted wood, metal, or plastic arm which converts the motion
of the control lines to up-and-down movement of the elevators in
a control line model aeroplane.
What occurs when the friction at a joint is stronger than the linkage.
Having fun flying, without any pre-determined flight pattern.
A solid steel wire used to support the structure of an airplane's
wings or fuselage. Turnbuckles are often used to tension the wires.
In the early days of aircraft design the biplane with bracing wires
and struts was the strongest design. The disadvantage of bracing
wires is drag. Although the wires may be small in diameter the drag
of these is a significant percentage of the overall drag of the
airframe.
'Buddy Box' or Trainer Box (back
to top)
Two similar transmitters that are wired together with a 'trainer
cord.' This is most useful when learning to fly - it's the same
as having dual controls. The instructor can take control if the
aircraft is too low or in a dangerous attitude by using the by using
the 'trainer switch' on his transmitter.
A very strong former within the fuselage used to mount the enging
or electric motor
An elastic chord used to launch gliders. A number of different
types of bungee are available with different characterisitcs.
Also known as crow. A mix which activates up flaperons and down
innermost flaps for gliding speed control without spoilers or air
brakes.
An instant type glue that is available in various viscosity's (Thin,
Medium, Thick, and Gel). These glues are ideal for the assembly
of wood aircraft and other materials. NOTE: Most CA glues will dissolve
foam although new 'Foam Safe Cyno' is available sometimes referred
to as 'Odourless Cyno' If you're not sure always test it on a scrap
piece first. Commonly known as 'Super Glue'
'CG' or 'C of G' = Centre of Gravity (back
to top)
For modelling purposes, this is usually considered the point at
which the aircraft balances fore to aft. This point is critical
in regards to how the aircraft reacts in the air. A tail-heavy plane
will be very snappy but generally very unstable and susceptible
to more frequent stalls. If the aircraft 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 aircraft will have to come
in faster to land safely. The CG should always be checked on every
new model and only when the fuel tank is empty.
The spot where the lift of a wing (or wings) is said to centre.
The point on the upper surface of a wing. Relative to the chord.
Where the lift can be said to centre.
The strut assembly at the centre section of a biplane or Parasol
monoplane.
The curvature of the wing or horizontal tail, from the leading
edge to the trailing edge.
An aeroplane designed to fly with its tailplane in front of the
wing, it also refers to a forward horizontal stabiliser. Some aircraft
have canards in addition to a conventional horizontal stabiliser
on the tail.
The part of the engine which controls the speed or throttle setting
and lean/rich mixture via setting of the needle valve.
A nitrocellulose varnish like liquid used to shrink fabric onto
a frame. Care should be taken to carefully read manufacturers instructions
and work in an open environment as the fumes can become very overpowering.
The frequency number used by the transmitter to send signals to
the receiver. If radios transmit on the same frequency, or channel,
glitching will occur in the active receiver on that channel. This
is due to conflicting signals sent by the two transmitters. Flying
sites should have a frequency control system to ensure that only
one radio operates on any given channel at one time. This is usually
a board with some type of marker for each channel. If the marker
is not available, someone else is using that channel. Do not use
your radio unless you are sure you are the only one on the frequency.
Click here for a full listing of 35Mhz channels used in the UK for
model flying
The number of functions your radio can control. Eg: an 8 channel
radio has 8 available servo slots used for separate control surfaces
or switches. These channels can also be mixed on many radios.
The plug receptacle of the switch harness into which the charger
is plugged to charge the 'Receiver Pack'. A 'Battery Checker' can
also be plugged into it to check battery voltage between flights.
If you are not using an onboard battery checker (I highly recommend
that you do fit a battery checker on all your models) It is advisable
to mount the charge jack in an accessible area of the fuselage so
a battery checker can be used without removing the wing.
Device used to recharge batteries and usually supplied with the
radio if Ni-Cad batteries are included.
A stick used to 'flip start' a model airplane engine and hence
save your fingers from getting caught in the propeller when the
engine starts or backfires.
The width of a wing or tailplane from front (leading edge) to back
(trailing edge).
A small plastic or metal clip that is used to connect either a
pushrod or closed loop connections to either the servoe arm or a
control horn
A set up using two wires. One is pulled for one direction, the
other is pulled for the other normally used on the rudder of aircraft
and provides positive control.
A fuel tank where the fuel pickup (the 'clunk') is at the end of
a flexible tube. Gravity ensures that the clunk is always at the
bottom, enabling fuel to be collected whatever the orientation of
the fuel tank.
Usually refers to a type of structure made with layers of fiberglass
or fiberglass-like materials such as carbon fibre. The materials
are called composites.
Contra-Rotating Propellors (back
to top)
Two propellors on the same axis rotating in opposite directions.
It is a convenient method to increase power for a given propellor
diameter.
An arm fastened to a control surface to which is connected the
control rod.
Parts of an aircraft that are activated by the pilot or servos
(in the case of a radio-controlled model) to change the airflow
around the surfaces of the aircraft. The changes in airflow cause
the aircraft to roll, pitch, or yaw.
'Control Line Turn' or 'Flat Turn' (back
to top)
Is a 360° turn without using the ailerons just rudder. Control
line aircraft go round in circles with their wings horizontal or
flat, they dont bank.
In a conventional servo, the motor has a steel core armature wrapped
in wire that spins inside the magnets. In a coreless design, the
armature uses a thin wire mesh that forms a cup that spins around
the outside of the magnet eliminating the heavy steel core. A coreless
motor does not have magnets as standard servo motors do, so they
have a smoother, more constant, and stronger action. Regular servo
motors have either 3 or 5 magnets (poles) which when the armature
is between these, the servo motor is at its weakest.
A specially shaped nose to enclose an engine.
Also known as butterfly. A mix which activates up flaperons and
down innermost flaps for gliding speed control without spoilers
or air brakes.
A component used to determine the operating frequency of a Radio
Transmitter or Receiver. The frequency or Channel of R/C equipment
can be changed by plugging in the appropriate crystals.
An instant type glue that is available in various viscosity's (Thin,
Medium, Thick, and Gel). These glues are ideal for the assembly
of wood aircraft and other materials. NOTE: Most CA glues will dissolve
foam although new 'Foam Safe Cyno' is available sometimes referred
to as 'Odourless Cyno' If you're not sure always test it on a scrap
piece first
DSC = Direct Servo Control (back
to top)
High-end convenience feature which allows control/adjustment of
servo function without sending signal through receiver. Requires
optional DSC cord.
A reference line or point from which measurements are taken.
A term used to describe unpowered flight (glide) when the engine
stops.
Markings come in many different forms and are normally provided
with the kit.
An aircraft with a wing of a triangular planform, the base of the
triangle forms the trailing edge.
Delta Peak or Peak Charger (back
to top)
This type of charger will eliminate the guesswork. When the battery
is full it 'peak', this type of charger detects this 'peak' and
then switches to a trickle charge, which will not damage the battery
pack.
Slang term for the condition in which the model is set up to fly
smoothly and predictably. This is the state where the mechanics
and electronics work together to produce the best performance.
Diesel engines can offer a lot in terms of power to weight ratio
and the ability to turn a large propeller.
Differential or Aileron Differential (back
to top)
Because the downward travel of the aileron causes more drag then
the up travel, sometimes it is necessary to have a lower amount
of travel in the downward direction compared to the upward direction,
the differential can be set up either mechanically of electronically
in a programmable computer transmitter. The extra drag of the downward
moving aileron can in some aircraft cause a 'yaw' effect making
rolls look untidy, by reducing the downward travel you will get
better looking more axial rolls from your aircraft.
The upward 'V' angle of the wings when viewed from the front expressed
in degrees i.e. 4°
An electronic component which only allows current to flow one direction.
Protects a transmitter against reverse polarity or power surges
during charging.
A wheeled frame that a model sits on to effect a take-off. The
dolly either remains on the ground or drops off almost immediately.
The slight tilting down of the engine or propeller thrust line
to exert a slight downward pull under power.
In the circuit flying parallel with the runway in the opposite
direction to take-off, i.e. going in the same direction as the wind.
A type of receiver that converts the incoming frequency through
two intermediate stages. It allows the receiver to be much more
sensitive only to the channel it is using and blocks out external
frequencies. This is what helps the receiver to be very narrow-band,
in other word it's a good feature.
A switch on the transmitter that can bet set so that the ailerons,
elevator and/or rudder can have reduced movement making the aircraft
less sensitive. Lower movements/rates are better for learners, who
tend to over control.
A small diameter multi-bladed fan, operated at high rpm inside
a tube or duct. The ejected air provides thrust in the same way
as a jet engine. The fan can be powered by an glow engine or an
electric motor.
ESC = Electronic Speed Controller (back
to top)
ESC's are only used in aircraft which are powered by electric motors
and are used to control the speed of electric motor(s).
Hinged control surface located at the trailing edge of the horizontal
stabiliser, which makes the aircraft climb or dive. Pulling the
transmitter elevator control stick back, toward the bottom of the
transmitter, makes the elevator move in an upwards direction, which
causes the aircraft to climb, and vice versa to dive.
An elevator split into 2 halves which can be operated independently
so that the same control surfaces can be used to control the roll
of an aircraft as well as the pitch. Often seen on Flying Wings
and Delta planform models.
Used to apply flaps along with elevators to increase lift, allowing
aircraft to fly at slower speeds, make tighter loops or turns, etc.
A two part glue that is extremely strong. It is generally available
in 5 minute, 30 minute and 1 hour formulas. The longer it takes
to set the stronger it is (i.e. 1 hour is stronger the 5 minute)
Used for critical places in the aircraft where high strength is
necessary.
Offers servo travel that is not directly proportional to stick
travel. Control response is milder below half-stick, but becomes
increasing stronger as stick travel approaches 100%. Great for aerobatics
and trouble situations. Makes highly aerobatic aircraft smother
to fly around stick centres
Frequency Modulation. This describes the mode of transmission of
radio signal from transmitter to receiver. 35 Mhz radios use FM
modulation.
A safety feature which sets servos to a pre-set position if the
signal is lost or interrupted. Additionally, battery fail-safe is
a safety feature which brings the throttle servo down to idle as
a warning that the receiver battery's voltage is getting dangerously
low. This feature is generally only available on 'high-end' radios
and the manufactures instructions should be read thoroughly and
understood before using as incorrect set up could be dangerous.
A streamlined cover over a joint or around angular parts of an
aircraft intended to reduce drag.
'Field Box' or 'Flight Box' (back
to top)
A box used to hold and transport all equipment used at the flying
field, electric starter, battery, tools, etc.
A rounded contour used at the junction of vertical and horizontal
surfaces on an aeroplane, to reduce air resistance.
A fast battery charger designed to work from a 12-volt power source,
such as a car battery, and used to charge the Ni-Cad's for either
your transmitter or receiver.
The non-moving surface that is perpendicular to the horizontal
stabiliser and provides yaw stability. This is the surface to which
the rudder attaches.
The last phase of a flight when lined up with the runway during
the landing approach.
A strong bulkhead immediately behind the engine on a powered aeroplane.
The movement of two aileron servos, both in the same direction
at the same time, acting as flaps. If mixed with elevators gives
very tight loops.
Hinged control surface located at the trailing edge of the wing
inboard of the ailerons (near the fuselage). The flaps are lowered
to produce more lift from the wing, allowing a slower take off and
landing. Flaps are often found on scale models, but not on trainers.
The point during the landing approach in which the pilot gives
an increased amount of up elevator to smooth the touchdown of the
airplane. Ground effect may result in the aircraft remaining airborne
for longer than expected.
'Flat Turn' or 'Control Line Turn' (back
to top)
Is a 360° turn without using the ailerons just rudder. Control
line aircraft go round in circles with their wings horizontal or
flat, they dont bank.
'Flight Box' or 'Field Box' (back
to top)
A box used to hold and transport all equipment used at the flying
field, electric starter, battery, tools, etc.
The battery that is used to power the receiver, and servos. The
flight pack is generally of the rechargeable Ni-Cad or Ni-Mh
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 causing a crash. There are many
reasons for this, but the most common is excessive hinge gap or
excessive 'slop' in the push-rod connections and control horns.
If you ever hear a low-pitched buzzing sound, reduce throttle and
land immediately.
An aeroplane with a fuselage shaped like a boat. For operation
off water.
Flying, Working or Moving Surfaces (back
to top)
This is a general term which groups together all the moving or
working surfaces i.e. Ailerons. Elevators Flaps (if fitted) and
Rudder.
A very strong former within the fuselage used to mount the enging
or electric motor.
The tips of the wing are forward of the leading edge at the root
of the wing. There are many problems with this design, one being
torsional stability resulting in flutter. The advantage is an almost
unstallable aircraft.
This is generally referred to as the system that is used at the
flying field so that a transmitter on the same frequency is not
turned on as an aircraft that is preparing to fly or is actually
flying. There are several types, so find out what system is used
and follow it faithfully as you don't want to be 'shot down' or
to shoot a fellow flyer down.
'Fun Fly' refers to a type of model aircraft that has been specially
designed for very slow 3D type of manoeuvres, generally not very
pretty, but good 'fun to fly' They have short, stubby but thick
wings. They are built very light and have very large moving surfaces
with lots of movement, good for 'prop hanging'.
The body of an aircraft that has the wing, horizontal stabiliser
and fin attached to it.
Although practical model jet engines have been around since the
early 1980's it has only been in the past few years that home construction
has become viable. Careful design has made simple home construction
possible using basic tools and a small centre lathe. Purchased items
can feature self starting and automatic shutdown. They generally
run on 'Jet A1' (same fuel as Jumbo jets use!) or domestic Parafin.
A term given to a 12V DC sealed lead acid rechargeable battery
that is commonly used to power either your electric starter or flight/field
box.
A latticework or basket-weave construction, a good example of this
is the rear fuselage construction of the Welligton WWII brithish
bomber.
A momentary loss of signal by the receiver making the model twitch,
this generally only happens when the model is low and far away.
Glitches can also be caused by interference generated on the aircraft.
When two metals touch a small amount of electrically generated noise
sometimes referred to as RFI is produced, and this can affect the
performance of the receiver. Never use metal clevices on engines
that have metal throttle arms for this reason.
The heat source for igniting the fuel/air mixture in the engine.
When starting the engine a battery is used to heat the filament.
After the engine is running, the battery can be removed. The wire
filament inside the plug is kept hot by the 'explosions' in the
engine's cylinder. See next heading and 'Idle Bar' plug.
A rapid circular rotation of a model on the ground, usually performed
while taxying or during take off. Taildragger aircraft are particulalrly
suceptible to this as they are sensitive to crosswinds.
Small strengtheners fixed at points of heavy stress in an aircraft’s
structure, normally triangular in shape.
A gyro is an electromechanical, or electronic device which aids
in the control of an R/C model. The gyro senses motion in one axis,
and directs the servo to counter that motion. The sensor, which
can be a mechanical gyroscope, or an electronic piezo crystal, detects
unwanted movement. The gyro then instructs the servo to counter
for that motion. At all times, the radio commands will override
the gyro command. The level of control the gyro had is adjusted
by the GAIN setting. Mechanical Gyro: uses a mechanical gyroscope
(similar to the child's toy) to sense movement. Piezo Gyro: uses
a piezo crystal to sense movement.
This describes a type of Gyro which senses rotation, and maintains
direction. This is accomplished by sensing the rate of motion, and
the time of motion, then compensating for the distance. While this
sounds complicated, the effect is that if you have the model dialed
in, and point the nose north, with a heading hold gyro on the yaw
axis the model will continue to face north until you command it
to yaw. See also Heading Lock. This is not recommended for aircraft
use while in flight due to the requirement to use YAW (rudder) command
to turn the model. Often used for ground use only for perfect take
off and landing runs.
Slang term for Heading Hold Gyro.
The horizontal tail surface at the back of the fuselage which provides
pitch stability to the aircraft.
IC or Internal Combustion Engine (back
to top)
A General term for glow, diesel or petrol burning engines
This is a setting on the transmitter which limits the throttle
minimum. Particularly useful for 3D style of flying.
The angle, relative to the fuselage datum, at which a wing is set.
Resistance of a wing to forward movement due to disturbance of
the surrounding air and related to the lift produced by the wing.
Flying up-side-down
A very light paper, usually made from rice straw, used for covering
some free-flight aircraft.
Although practical model jet engines have been around since the
early 1980's it has only been in the past few years that home construction
has become viable. Careful design has made simple home construction
possible using basic tools and a small centre lathe. Purchased items
can feature self starting and automatic shutdown. They generally
run on 'Jet A1' (same fuel as Jumbo jets use!) or domestic Parafin.
A fixture or form for holding parts together for assembly. A jig
is normally used where a series of parts need to be assembled in
the same way a number of times. However, when constructing a fuselage
a jig may be used to ensure alignment from front (engine mounting
position) to rear (tail surfaces mounting position).
Accelerates the curing of all "Cyno" glues, helps with gap filling
and hard-to-bond- surfaces - Smells awfull!
This is where the flow over the top and under the wing meet at
the trailing edge with no abrupt change in direction.
This is checked to make sure that the left hand side of the aeroplane
is the same weight as the right hand side when viewed from the top.
A rough check of the lateral balance can be carried out by holding
the tip of one blade of the propellor (when it's pointing vertically)
and the top of the fin. Add lead to either side to get the model
to balance.
A wing designed such that the air flow over it is laminar at zero
to small angles of attack. In Laminar flow the adjacent layers of
air flowing over the wing do not mix.
The axis extending through the centre of gravity of an aircraft
and parallel to the wing surfaces.
Ailerons give lateral control allowing the aircraft to be rotated
around its lateral axis.
The front edge of the wing or stabiliser.
The sum of all the aerodynamic forces acting on an aircraft at
right angles to the flight path. When the aircraft is in steady
level flight the lift is equal and opposite to the weight of the
aircraft. Wings create lift.
An aircraft that uses the shape of its body to generate lift instead
of using wings.
An aerobatic manoeuvre which combines extreme roll pitch and yaw
changes to produce a violent movement of the aircraft. The name
is derived from a Polish word which describes the effect of too
much liqueur spirit.
The main fore-and-aft strips in a fuselage.
An aircraft with a single set of wings mounted at or near the bottom
of the fuselage.
The unit of radio frequency. i.e. 35Mhz means that the signal
oscillates 35 million times per second, in other word the signal
rises and falls 35,000,000 times every second - That's a lot!
A cellulose lacquer solution poured onto the surface of a tank
of water to form an extremely thin film used for the covering of
F1D and other types of free-flight indoor aircraft.
Allows a single input to control the operation of two or more
servos. Simplifies routine flying and allows more involved manoeuvres,
great for intermediate and advanced fliers. For example, Flap-to-elevator
mixing: Most models will change pitch upon deploying flaps (some
will climb; others dive). After test flying the model and determining
the direction and amount of elevator throw required to correct for
this change, a pilot may set a flap-to-elevator mix to compensate.
Once the mix is operating properly, when the modeller gives flap
control, the radio automatically also gives the proportional amount
of elevator throw, keeping the model flat and straight.
A specialised lever which has three or more pivots. The length
between pivots will determine the proportion of the mix between
two or more linkages.
A removable unit is used in most computer radios, containing all
frequency control equipment, including the crystal and all tuned
components.
The distance between the point at which a force is applied and
the point of action of the force. For example, the distance between
the Centre of Gravity and nose, or Centre of Gravity and tail.
A form of fuselage construction with rounded exterior and very
little internal structure in which the skin carries virtually all
stresses.
An aircraft with only one wing.
Moving or Working Surfaces (back
to top)
This is a general term which groups together all the moving or
working surfaces i.e. Ailerons. Elevators Flaps (if fitted) and
Rudder.
American word for exhaust.
A radio with a 20 Khz band width. All Futaba radios produced 1992
or later and all Futaba FM and PCM radios ever produced are narrow
band.
The part of the engine which is used to control the mixture at
the 'Top End' to achieve maximum revs.
Ni-Cad (or Ni-Cd) = Nickel Cadmium Battery (back
to top)
Rechargeable batteries which are typically used to power transmitters
and receivers. If not properly cycled regularly they develop a 'memory'
and think they have a smaller capacity then they actually have.
A battery with a short memory can be returned to it's normal state
by several discharge/charge cycles. Ni-cad can be charged up to
600 times, but this is dependant upon many variables like charge
current, discharge current, temperature etc.
Ni-Mh = Nickel Metal Hydride Battery (back
to top)
Rechargeable batteries which can used to power receivers. Unlike
Ni-Cad batteries they do not develop a 'memory'. For the same electrical
storage capacity normally expressed in mAh (milli Amp/Hour) a Ni-Mh
battery is smaller and lighter. With every good side there is always
a bad side (Luke Skywalker/Darth Vader), Ni-Mh batteries cost more,
can not deliver high current compared to Ni-Cad's, can be tricky
to charge and must be used immediately after charging.
A fuel additive which makes a model engine idle smother and more
reliably as well as providing more power at maximum revs. It is
actually less combustible than Methanol. Methanol makes up the largest
percentage of model fuel. So why does nitro give more power? Well
the addition of Nitromethane allows more fuel into the combustion
chamber of the engine, which gives a bigger 'bang' which in turn
gives more power. The down side is that the engine has to run on
a richer fuel/air setting which means you tank of fuel won't last
as long. Another down side is that the more nitro a fuel contains
the more it costs. It is also thought to be corrosive to the internal
parts of an engine making the use of 'after run' essential. Ideal
nitro content varies from engine to engine. Refer to the engine
manufacturer's instructions for best results. Nitro content in fuel
is indicated by the percent of the fuel, i.e.'5%' indicates 5% Nitromethane
per volume.
A nose over is when due to long grass, binding wheels or just
the characteristics of the model (e.g. WWI models and Spitfires
are well known for this) the aircraft comes to rest on it's nose
or even flips onto it's back during take off or landing.
The supporting structure at the the very front of the aircraft
to support the front of the engine, normally used with big four
stroke engines.
A shock absorbing system used in undercarriages.
An aeroplane that flies by flapping its wings like a bird.
PCM = Pulse Code Modulation (back
to top)
PCM systems use digitally encoded signals to minimise interference
and provide today's most advanced RC control. This feature can be
dangerous if not set up correctly, please see the BMFA
Warning about PCM fail safes.
Pulse Position Modulation. Another term for 'FM'.
Described at first as the 'Guardian Angel'. On 19th August 1913
Pegoud was the first person to descend on a parachute in Europe.
An aeroplane in which the wing is mounted above the fuselage on
struts.
A particular style of aircraft that has been specially designed
to fly a set type of aerobatics. These type of aircraft generally
are of the 60 size and larger. Competition aircraft normally are
around 2 meter wing span, have deep fuselages and 1.40, 4 stroke
engines, needless to say they are at the more expensive end of the
hobby but are a dream to fly.
A style of flying encouraging large, very precise and smooth manoeuvres.
The point at which a battery will no longer accept a charge, and
converts the energy to heat. This is damaging to the battery pack,
and potentially hazardous. It is recommended to use a "Delta Peak
Charger" when charging any Ni-Cad batteries
Peak or Delta Peak Charger (back
to top)
This type of charger will eliminate the guesswork. When the battery
is full it 'peak', this type of charger detects this 'peak' and
then switches to a trickle charge, which will not damage the battery
pack.
The aircraft's up/down attitude is controlled by the elevator and
is referred to as the pitch. Pitch is illustrated by holding the
aircraft at each wing tip. Raising or lowering the nose is the pitch
movement. This is how the climb or dive is controlled.
Sheet-wood covering accomplished by glueing thin flat wood strips
side by side on a fuselage.
Sheet wood made by glueing together two or more very thin layers
of wood with the grain of adjacent layers at right angles.
A form of dihedral in which there are one or more changes of dihedral
in each wing panel.
12-volt distribution panel that provides correct voltage for accessories
like glow-plug clips, fuel pumps and electric starters. Usually
mounted in a field/flight box and connected to a 12-volt 'Gel Cell'
battery.
A pre-flight check should be carried out every time you visit the
field, it includes amongst other things a 'radio check', making
sure the engine, propellor, spinner, wheels (if fitted) and flying
surfaces are all secure. Flying surfaces must also be checked
to make sure they are moving in the right direction. If you are
not sure how to perform all these checks, ask a fellow flyer, I'm
sure they will be willing to help.
An assembly of radially disposed blades with an airfoil shape that
when rotated in air produce thrust.
An assembly of radially disposed blades with an airfoil shape that
when rotated in air produce thrust.
Props are designated by these two numbers, for instance 10 - 6
(often pronounced 10 by 6). The first number is the prop's length,
10'. The second number is the pitch or angle of the blades. The
6 represents the distance the propeller will move forward in one
revolution, in this case 6'.
Pull-Pull or 'Closed Loop' (back
to top)
A set up using two wires. One is pulled for one direction, the
other is pulled for the other normally used on the rudder of aircraft
and provides a more positive movement.
A plane in which the engine is mounted ahead of the propeller,
so that the propeller pushes instead of pulls.
A water based type of adhesive.
Abrievation for 'Radio Controlled'
An engine design where the cylinders are designed symmetrically
around a central crankshaft and hence radiate out.
A moulded plastic or metal mount which is fastened to the mounting
lugs of an engine and then bolted directly to the engine bulkhead
or firewall.
A type of jet engine with very few moving parts which consists
of a specially shaped tube open at both ends in which air is compressed
purley from the forward speed. The addition of fuel and this being
then ignited increases the volume of air. Note that ramjets only
operate above certain speeds.
A measure of the speed with which an airplane rotate around its
long axis, or roll. This is normally measured in degrees per second.
A switch on the transmitter which changes the amount of movement
of a control surface when the stick is moved.
A tool for making holes bigger.
The radio unit in the aircraft which receives the transmitter signal
and tells the servos which direction, what speed and where they
should stop.
A reversal of the camber on a flying surface. Often used on flying
wing or delta planform aircraft.
This is the vibration frequency of a rotating or moving object.
When the resonance of many parts of a machine are in synch, the
whole machine will vibrate at a greater rate. This can cause vibration
damage. Resonance can cause difficulties in an aircraft, particularly
when using a anti-vibration mount with an improperly balanced propeller/spinner
where the engine is vibrating at one frequency and the propeller
at another. Vibration can also cause the airframe to resonate causing
at best extra noise and at worst failure in the airframe causing
a crash.
When the undercarriage folds up into the wing, normally only used
on scale aircraft and 'pattern' aircraft which can be operated either
mechanically via a special 'retract servo' or pneumatically via
a valve which is operated via a standard servo
Slang for retractable undercarriage.
Specifically used for mechanical retracts. It is a powerful non-proportional
servo which only moves 180 degrees. That is to say this servo is
either 'off' (gear up and fully locked) or 'on' (gear down and fully
locked). No ATV, EPA, or AST adjustments can be made on these servos
because they are not proportional. The linkage must be set up properly
to allow this servo to operate at its full range and do its job.
The cross-section shape of a wing, from leading to trailing edge.
The aircraft axis controlled by the ailerons. Roll is illustrated
by holding the aircraft by the nose and tail. Dropping either wing
tip is the roll movement. This is used to bank or turn the aircraft.
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.
The part of a wing where it meets the fuselage.
An air cooled engine whose cylinders, arranged like the spokes
of a wheel, rotate around a fixed crankshaft. The fuel is supplied
to the engine through the crankshaft and the engine normally exhausts
straight out the top of the cylinder. This arrangement was used
with early engines as the mass of the engine was used as the flywheel
allowing the engine to run smoothly.
Hinged control surface located at the trailing edge of the vertical
stabiliser, which provides control of the aircraft about the Yaw
axis and causes the aircraft to Yaw left or right. Left rudder movement
causes the aircraft to Yaw left, and right rudder movement causes
it to Yaw right.
Mix used to counteract undesirable roll which often happens with
rudder input, especially in knife edge, also called roll coupling.
Abbreviation for receiver.
SMT = Surface Mount Technology (back
to top)
Ultra light, solid-state components which offer greater vibration
resistance and reliability.
American word for a glider
The electromechanical device which moves the control surfaces or
throttle of the aircraft according to commands from the receiver.
It's the device which does the physical work inside the aircraft.
Reverses the rotation of a servo with the flip of a switch. Adds
ease and flexibility during installation.
The removable arm or wheel which bolts to the output shaft of a
servo and connects to the push-rod. Careful positioning of the holes
in the output arms will allow you to produce a mechanical differential
effect for airlerons or even throttle control where more precision
is required around the idle setting.
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.
The direction of flight is at an angle to the fore aft axis of
the aircraft.
Offsetting the propeller thrust line, so there is a slight sideways
pull. Side thrust is used to counteract the effects of the torque
of the engine. The courser the pitch of the propellor used, the
more side thrust is needed.
A device used to reduce noise from the exhaust side of an engine.
The reason for a crash due to another person turning on a transmitter
on the same frequency as a flying aircraft causing loss of control
of the flying aircraft and subsequently the inevitable crash.
Slats are used on the leading edge of a wing to improve lift. They
help the formation of a smooth boundary layer over the leading edge
allowing the wing to operate at a higher angle of attack before
seperation occurs.
The column of air pushed rearward by a rotating propeller; it always
moves faster than the aeroplane itself.
Unwanted, excessive movement in a control system. Often caused
by a hole in a servo arm or control horn that is too big for the
push-rod wire or clevis pin. This condition allows the control surface
to move without transmitter stick movement. Also, see flutter.
No, not a legless reptile but a flexible pushrod consisting of
a plastic or braided metal wire inner, inside a plastic sleeve.
Combines rudder, elevator and aileron movement to cause the aircraft
to snap or spin on the flip of a switch.
A plastic film that is used to cover models, it has a heat sensitive
glue on the back which sticks to the balsa wood. It also shrinks
when heat is applied giving that bright shiny drum like finish.
It is fuel proof against glow fuel but not petrol or diesel
A very thin plastic film that is used to put markings and patterns
on models, it has a sticky back. It also shrinks when heat is applied.
It is fuel proof against glow fuel but not petrol or diesel
Your first totally unassisted take off, flight and a controlled
landing.
Spanwise load-carrying members of a wing or tail.
The rapid rotation of an aircraft after it has stalled. In order
to recover the aircraft it is necessary to first increase the airspeed
so that the flying surfaces are no longer stalled.
An ever-tightening downward corkscrew flying path.
The characteristic of an aeroplane that permits high-speed banked
turns without diving to the ground.
The nose cone which covers the hub of the propeller. Check that
the spinner does not touch the propeller blades as this may result
in the propeller blades wearing and possibly failing. Remember a
large spinner will result in less effective propeller area and a
reduction in engine cooling.
Controls which can be deployed into the airflow to "spoil" the
lift. Usually found on gliders and used to aid landing.
A surface that is used to stabilise the aircraft during normal
flight e.g. the tail fin and tailplane. Other designs such as a
V-tail may be used to provide both pitch and yaw stability.
The tendency of an aeroplane to return to level flight, after having
been disturbed by an upsetting force.
What happens when the angle of attack is too great to generate
lift regardless of airspeed. (Every airfoil has an angle of attack
at which it generates maximum lift, the airfoil and aircraft will
stall beyond this angle). A stall can be recognised by a sudden
uncontrolled drop of a wing at slow flying speed, this drop of a
wing is often followed by a spin if not caught quickly.
The time spent actually flying your model aircraft.
Short Take Off and Landing. Describes an aircraft with special
high-lift devices to keep the take off or landing run as short as
possible.
Light, lengthwise fuselage strips intended more to give the desired
shape than to add strength.
Ailerons consisting of simple strips along the full length of the
wing trailing edge.
This is a trim function on many computer radios, allowing minor
trims inputs to be stored electronically in the transmitter so when
a different model is selected from the transmitter's memory this
model will fly true when the trims are set to their centre position.
The leading and trailing edges of a wing are angled backwards to
reduce drag at high speeds.
Is the name given to the small electrical switch and wires that
is installed in the aircraft to turn the receiver on and off.
Arrangement where the tailplane is mounted on top of the fin.
A small adjustable surface on wing or tail surfaces, used to make
small trim changes.
An optical sensor designed specifically to count the speed of a
turning propeller and display it as RPM (Revs Per Minute)
An aircraft which has an undercarriage arrangement where the mainwheels
are under the wing with smaller wheel at the tail end of the fuselage.
The aircraft sits on the ground with a nose-high attitude.
A mixture of elevators and ailerons. On a delta wing the elevators
and ailerons are mixed and known as elevons. However, as well as
normal ailerons the tailplane horizontal surfaces may be mixed to
form elevators and ailerons and hence enhancing the normal roll
control provided by the ailerons.
A fixed angular fixture use to support the tail end of an aircraft
on the ground instead of a wheel.
An airplane with wings of similar size mounted one in front of
the other, on pretty much the same level.
A stiff pattern for marking the outlines of pieces to be cut from
sheet wood or metal.
A rising column of relatively warm air.
With a tail dragger there is an art in landing with all three wheels
touching the ground at the same time.
The programming function of the radio which allows throttle operation
to be adjusted to meet the modeller's specific needs at various
points along the throttle movement. Particularly useful with 2-stroke
engines in providing linear throttle response at the various points
of throttle application.
The propulsive force developed by a driven propeller or jet engine
An imaginary line drawn along the propeller shaft and extending
rearward through the aeroplane.
The outboard end of one wing 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.
Rudder used when an aircraft is flying on its side (knife edge)
to keep the flight path horizontal.
The force which causes rotation. When viewed from the front a propellor
rotates in an anticlockwise rotation, the airframe then wants to
turn in a clockwise direction.
An aerobatic manoeuvre that uses the torque reaction to accelerate
the rate of roll of an aircraft.
Landing and taking off without a pause. Useful to practise when
learning to fly.
The rearmost edge of the wing or stabiliser.
A model designed to be inherently stable and fly at low speeds,
to give first-time flyers time to think and react as they learn
to fly.
This is the unit that you hold that sends radio waves to the receiver
the aircraft which in turn tell s the servos what to do which gives
control of the aircraft.
When model takes off for the first time, there is no way of knowing
exactly what's going to happen, some models will climb, while others
may want to dive, some will try to turn left, others right. Some
models will be doing both at the same time on the first flight.
It doesn't mean that there is anything wrong with the model, but
these minor differences must be 'trimmed out' for the model to fly
straight and level. That's why a new model's first flight is best
done by an experienced model pilot. Someone whose reflexes are already
conditioned to anticipate the model's actions and instantly make
the right move to counteract it and save your new pride and joy.
An undercarriage arrangement where the main wheels are set under
the wing just behind the center of gravity point, with the third
wheel positioned under the nose just behind the engine. The aircraft
sits on the ground with the fuselage level.
The two stroke engine has been the main stay of powered model aircraft
for a number of years due to the high power to weight ratio. The
main downfall of the two-stroke engine is the high fuel consumption.
The basic construction, operation and general notes on starting,
running and maintaining are all included within this section.
Abbreviation for transmitter.
Ultra High Frequency.
The concave curve on the underside of some aerofoils.
The wheel and strut assembly that supports an aeroplane at rest
on the ground and during take-off and landing.
Used on a V-tail model to have two servos operate two control surfaces
that act as both rudder and elevator.
A tube reduced in diameter at its centre. Air flowing through it
is speeded up by the change in shape.
The non-moving surface that is perpendicular to the horizontal
stabiliser and provides yaw stability. This is the surface to which
the rudder attaches.
Very High Frequency.
Air from the high pressure region under the wing flows to the low
pressure region above the wing when generating lift, the result
are vortices. This reduces the effective lifting area of the wing
and generates drag. If the wing span was very very long the loss
due to this flow from bottom to top would be very low and the induced
drag very low. This is why high aspect ratio wings are used where
low drag and high lift is required e.g. gliders.
Twist incorporated in wing tips to raise the leading edge, to give
more incidence at the tip than at the root. Generally not a desirable
condition as it makes aircraft tip stall easily.
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.
American version of 'Wheel Spats'
Designed to reduce the drag of fixed undercarriages by providing
an aerodynamic shroud over the top section of the wheels.
The main lifting surface of an aircraft.
Expression for the weight per unit wing area of a model. Thermal
gliders might have a wing loading of around 10 or 12 ounces per
square foot. Large scale power models may be over 24 ounces per
square foot.
The chord-wise cross section of a wing. Since the first days of
flight wing sections have been continually changing and optimised
for different aspects: lift, drag, low speed, high speed, strength.....
The distance from wing tip to wing tip
The earliest form of roll control was produced by warping the whole
wing. Raising the trailing edge of the right hand wing and lowering
the trailing edge of the left hand wing will result in the aircraft
rolling to the right.
Working, Moving or Flying Surfaces (back
to top)
This is a general term which groups together all the moving or
working surfaces i.e. Ailerons. Elevators Flaps (if fitted) and
Rudder
The rudder on an aircraft controls yaw,moving the rudder left or
right causes the nose to move to the left or right, this movement
is referred to as 'yaw'.
A simple Z-shaped bend in the wire end of a pushrod, which is used
to attach the pushrod to a servo output arm. When using a z-bend
to link to the throttle arm on the engine carburettor care should
be taken to avoid metal to metal links as these can result in radio
interference.
An inexpensive plier type tool used for easily making perfect Z-bends.
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