Model Aircraft Glossary

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Sailplane

See glider.

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Scale

The debate as to what is scale and what is not will go on and on.

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Service Ceiling

The altitude above sea level beyond which an airplane can no longer climb more than 30 m (100 ft) per minute.

Servo

A motor-driven device for moving control surfaces and throttle of a radio controlled aeroplane.

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Servo Output Arm

The removable arm or wheel which bolts to the output shaft of a servo and connects to the pushrod. These are often cut and modified to suit the paricular application. 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.

See also: Servo

Servo Reversing

This radio feature allows you to install the servos where they can give the best pushrod routing without concern about the direction of servo rotation. When your installation is complete, turn on your radio and check each channel. If a channel operates opposite of its intended direction, a simple flick of a switch corrects the problem.

See also: Servo

Side Slipping

The direction of flight is at an angle to the fore aft axis of the aircraft.

Side Thrust

Offsetting the propeller thrust line, so there is a slight sideways pull.

Sidewinder

Colloquial expression describing an engine mounted on its side.

Silencer

A device used to reduce noise from the exhaust side of an engine.

See: Exhaust.

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Simulators

Flight training from your armchair. A great way to sort out your skills.

Further links: Preflight3D

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Single-Surface Wing

A wing formed from a single sheet of balsa, or one that has a framework covered only on the top.

Slats

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.

See also: Flaps.

Slipstream

The column of air pushed rearward by a rotating propeller; it always moves faster than the aeroplane itself.

Slope Soaring

In the simplest terms it is flying a glider in the updraft created by the wind blowing on-shore and up a cliff.

Snake

A type of flexible pushrod consisting of a plastic or braided metal wire inner, inside a plastic sleeve.

Solid Model

A non-flying model formed from solid pieces of wood or plastic.

Spars

Spanwise load-carrying members of a wing or tail.

Spin

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.

Spiral Dive

An ever-tightening downward corkscrew flying path.

Spiral Stability

The characteristic of an aeroplane that permits high-speed banked turns without diving to the ground.

Speed of Sound

The speed of sound is about 340 m/s or 760 mph at sea level.

Spinner

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.

Spoilers

Controls which can be deployed into the airflow to ‘spoil’ the lift. Usually found on gliders and used to aid landing.

Stabiliser

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.

Stability

The tendency of an aeroplane to return to level flight, after having been disturbed by an upsetting force.

Stall

The complete loss of lift resulting from too steep an angle of attack.

Stalling Angle

The particular angle at which a wing abruptly loses lift; usually expressed in degrees.

Starter Motors

See: Internal Combustion engines for methods of starting.

Stick

The operating arm on a transmitter which is moved to make the control surface move.

Stitching

A step by step article on creating simulated stitching effect on fabric. more......

STOL

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.

Streamlined

The shape of the exposed contours of an aeroplane for the least possible air drag; usually rounded in front, pointed at the rear.

Stressed Skin

An outer covering used on wings and fuselages, designed to carry the tension and compression forces encountered in flight.

Stringer

Light, lengthwise fuselage strips intended more to give the desired shape than to add strength.

Strip Ailerons

Ailerons consisting of simple strips along the full length of the wing trailing edge.

Subsonic

Speeds below the speed of sound.

Supersonic

Speeds above the speed of sound.

The first aircraft in the world to break the sound barrier was the Bell X1. On the 14 October 1947 it reached 670mph at 42000feet (Mach 1.015). The X1 was launched by a Boeing B29 at 30000 feet, once released the rocket motor on the X1 was fired and it would begin it's ascent.

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Sweepback

The angling back of the wings from the centre, to increase directional stability or reduce drag at high speed.

Swept Wing

The leading and trailing edges of a wing are angled backwards to reduce drag at high speeds.

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