Hi Paul,
I have used some of those spinners in the distant past.

Like everyone says, Royal was big into scale R/C kits. I always wanted the B-17 kit, myself, and do have a KI 61 Japanese Tony in their ".40" line. Not 100% scale, but pretty good looking, all wood kits. Great for Stand Off Scale!
A Japanese sounding company was selling them for a while, but I think they quit about 10 years ago. Maramu or something.
A company is selling their plans and canopies/cowlings on ebay all the time.
I have a Royal .45 engine that I have yet to run which I bought from Dale Barry about 15 or more years ago.
Good quality from all I remember.
Big Bear