Film about the SR-71 blackbird airplane made in the 70’s or 80’s. I saw a reference for it on discovery channel. It appeared to be a feature film.?

Hello there. The film you are talking about is D.A.R.Y.L released in 1985.
Its basically about a sissy robot child built by DARPA. Its a kids film and eragonfilm.com in the end D.A.R.Y.L ends up stealing a SR-71 blackbird in order to…. actually I wont spoil it….