Servo
An electronic device, that converts the received radio signal into mechanical movement, allowing control surfaces to move.

Servo Reversing
This function reverses the rotation of a servo.

Servo output arm
An arm or wheel that attaches to the output shaft of a servo to which control linkages are attatched.

ServoSync™
An ingenious new feature that resequences the DX7 signal, based on the type of mixingyou select, dual elevator for example, ServoSync ensuring that both servos receive their impulses together.

Slats
Moveable surfaces on the leading edge of the wing that helps airflow in low speed flight this enables the wing to fly at lower airspeeds.

Slop
Unwanted movement in a control system.

Smart-Trak™
Onboard software that uses time-based calculations to adjust control surface travel so that you can enjoy excellent responsiveness at all throttle settings without over-controlling.

Solo
The first time you fly your plane unaided by an instructor.

Span
Refers to the straight-line measurement between the two wingtips.

Speed brakes
A panel that folds out of the aircraft structure to provide a lot of extra drag in order to slow the model down.

Spin
A model rotating around its horizontal axis in a nose down attitude while descending at a high rate of speed.

Spinner
A moulded cone shaped accessory around the propeller this smoothes the airflow around the propeller and makes the plane look better, and a useful safety feature

Spoiler
Control surface on the upper surface of the wing that may be deployed to induce drag and reduce lift.

Stall
A stall occurs when the angle of attack of the wing is too great to generate lift, or the stopping of an electric motor under load, in a servo for example.

Strut
Basically this is a supporting member, usually from the fuselage to the wing, or from the landing gear to the fuselage.

Sub Trim
Trim function found on some radios, allowing trim function during set-up, and still allowing the full trim function in flight.