Complex sentence: One of the first, flying from 1984, was the experimental Grumman X- 29, of basic canard configuration but with movable flaps mounted on strakes extending rearwards from the main wing roots.
Split into simpler sentences: One of the first, flying from 1984, was the experimental Grumman X- 29. Of basic canard configuration, the X- 29 also had movable flaps mounted on strakes extending rearwards from the main wing roots.