An interesting find the D-1 can be quite the rare site with only 12 built and 9 still registered as of 2009. It was designed by John Thorp famous for being the lead on the preliminary design team for the T-16 / PA-28 for Piper and the Thorp T-18 kit-plane. The prototype was originally powered by O-200 engines but where later upgraded to more powerful IO-320′s.

It’s quite the good looking twin but due to many factors it was not produced in mass.

YouTube videos are very limited, here are a few I found:

x-plane has a download for the D-1

https://forums.x-plane.org/files/file/39264-wing-aircraft-co-d-1-derringer/

No Dice for RC options on Outerzone, surprising as it looks like it would be an easy balsa build.

There are 3 other Thorp designs for the T-18 on OZ: https://outerzone.co.uk/search/results.asp?keyword=thorp