The Trainer 40 was originally the RCM Trainer (see picture
attached) it was marketed by Bridi and called the RCM Bridi Trainer. Bridi also marketed a kit of an enlarged version, called the Trainer 60 (which I had), Kraft also had a version of the 40 called the Krafty. GP picked up the rights and marketed theirs. There is a wealth of info on the RCU Forums. Just use RCM Trainer, or Bridi Trainer 40, and you will bring up the history. I think they are all basically the same plane, except the first versions had a rubber banded wing and later it was bolt on. Other subtle changes for manufacturability were made I am sure. It was a great design that would still be so today. There are good plans on one of the RCU sites. Enjoy yours.
Sincerely, Richard