Hi BEM.
The Drringer is almost exactly the same... but still not it. There are better pics of the Derringer on the Trenton web site such as [link]http://www.trentonrcflyers.com/pattern/derringer-4rt.jpg[/link]

You can see the "canopy" is more forward and it seems smaller. The underside of the nose is more tapered. It seems the cross section of the fuse is smaller with no possibility of running the pipe internally. But dang.. they are sooooo close. The stab and rudder profiles are very close. There is a difference in that the Derringer elevator leading and trailing edges are parallel while the elevator on my unknown model is tapered.

Both models have very similar wing fillets. The Derringer seems to have a little difference where the rudder meets the fuse. I think the Derringer trailing edge is straight as well whereas my model has a swept wing.

They are so similar, though, that I wouldn't be surprised in one was "developed" from the other. And it really is hard to tell them apart from that newspaper article photo. I think 1977 totally nails the vintage.

Tom