11/30/2012. The S-51D is a 70% scale all aluminum replica of the North American P-51D Mustang, powered by a Chevy eight-cylinder V-engine. Designed by Jim Stewart the pictured aircraft was built by a Mr. Howard in 1985, and received its CofA on July 1 of that year. It is still airworthy as of this day. Additional photo (site files)