So, this is stating that electrics are allowed as long as they are of similar power? It still doesn't appear to clearly exclude electrics from 1/2A scale.
I knew you were going to try to make that point.
It's an unfortunate issue of semantics. I do not interpret "motor" to mean "electric motor". "Engine" and "Motor" are synonymous in common usage, irrespective of their accepted engineering meanings. So far as I could find, there is no definition of terms in the Competition Regulations that would apply.
1/2 A Scale was created as a class to give people the opportunity to see what sort of models could be built using simple .020 - .061 glow ( or diesel) power. The result has been pretty impressive. The essence of the class is the engine / motor. Electric does not fit.
There are four other scale classes that are open to electric power; Fun, Profile, Sport, & Authentic. There is nothing to say that a model of similar size to a 1/2 A powered by an electric motor (s) could not be flown in one of those classes and be competitive.
Controline General Rule Para. 11 further specifies class engine sizes.
11. Nominal Classification of Control Line Models. Models powered by reciprocating engine(s) are classified by total piston displacement of engine(s) as follows. Class ½A 0000—.0504 cubic inch Class A 0505—.1525 cubic inch Class B 1526—.3051 cubic inch Class C 3052—.4028 cubic inch Class D 4029—.6500 cubic inch Jet Internal cross-sectional area of the tail pipe(s) at the point of minimum cross-section shall not be greater than 1.25 square inches. Turbine The Maximum static Thrust to Weight ratio shall be .9 (dry).When the description "1/2A" is used to define a class it clearly means a reciprocating engine/motor not an electric motor.