Editing Control line (section)

===Scale===
Scale is an event where an accurate scale model of a real aircraft is flown. Scoring is based on static judging of how closely the aircraft resembles the full-size prototype and on the flight performance. Extra points are often awarded for "working" features of the model, such as a retractable landing gear, droppable bombs, and other functions or operations. The number of features used to be limited by the number of lines that could be practically used to mechanically control them.

Some complex scale models use a fly-by-wire approach to allow a multitude of extra working features. A radio-control transmitter's encoder unit can be adapted, with no RF signal board present, to send its control signals along insulated control lines, instead of broadcasting them using radio frequencies. If signals are sent down the lines, the normal serial multiplexing of the control signals by such an adapted RC transmitter's encoder unit, solely sending those signals along the usual duo or trio of control lines, gets picked up by decoding gear in the model - usually adapted from an RC receiver, without an RF "front end" section - and permits many functions to be controlled without the use of additional lines. Standard [[Servomechanism|servo]]s can then be used in the model. From 2013, in the USA, the radio control "over the airwaves" of any moveable feature of control-line Scale or Carrier models (except the elevator) is permitted - this may spread to Europe and beyond in time.