The ELG nomenclature, describing a “Electric Launched Glider” class of model, covers the current definition of electric powered soaring gliders to BARCS rules.
It has been difficult getting stable rules for this class of glider due to the on-going technology developments in electric power. Without going into detail on the rules, these models carry a height limiter device causing a motor cut off at 200 metres (but for the present models may alternatively comply with a power loading of 200 watts/kilo). No limitations are placed on the type of battery used and Lithium Polymer technology is now generally used.
Increasingly the models used are multifunction in nature, rather than being essentially rudder elevator types, this allows for greater precision in the all important landings. It is vital to keep the model light however with the micro servos now available, such multiple control surfaces only add modest extra weight. As the models do not have to take the stresses induced in towing the wing structures can be lighter thus helping to minimise model weight. Indeed electric conversions of wooden constructed gliders have proved to be very competitive.
Many models use such wooden construction or are electric versions of F3J type moulded gliders, however the Eastern European constructors have also entered the field with a few very lightweight designs with open framework construction, a technique which owes much to free flight practice.