RE: Sterling Spitfire Kit
Yes, That's right.
Sterling kitted a 65" RC version from around '63 to the early '70s. The Kit was based on the George Harris design of about 1961. It had fixed undercarriage and an upright engine and was designed to fly on reeds. Didn't have anything else then. They also kitted a F-51 Mustang in the same era. These were very advanced for their day and very popular. However, I have oftened wondered how many ever made successful flights, because these was quite difficult projects considering the state of the art in those days. Both are very collectable today.
Sterling also produced a very succesful Spitfire control line. It was quite large and a good flier. It too, is quite collectable. They seem to be more plentiful that the RC counterparts.