Embryo class planes have wing are limited to a maximum of 50 square inches. The Prairie Bird is a very popular beginner Embryo with a long history. Its wingspan is 16 inches and wing area is 48 square inches. A kit is available at https://www.wind-it-up.com/ A nice YouTube video of a successful flight has been posted by joshuawfinn entitled “Peck Prairie Bird, take 2” June 2009. A how-to article may be found at http://www.theplanpage.com/things/pb/pb.htm
Rubber Scale is a broad category covering lots of prototype aircraft. The Cessna 140 in the picture also falls in the Modern Civil class. It also gets no bonus points since it is a high wing plane with one engine. Under FAC rules a multi- engine biplane would get handicap points compared to a high wing monoplane like the Cessna. These planes are judged on resemblance to a specific prototype aircraft, including markings. There are designs with rugged or light construction, adapted to outdoor or indoor flying.
Peanut scale models are judged like the broader Rubber Scale class, but have a wing span limited to 13 inches. The Peanut Scale model of a Martin MO-1 1920’s Naval Observation Plane was built using a plan from Model Aviation by Dave Linstrum.