Complex sentence: The M.39B Libellula (from Libellulidae, the taxonomic name for dragonflies) was a tandem wing research aircraft built by Miles Aircraft; a scale version of the M.39 proposed by Miles to meet Air Ministry specification B.11/41 for a fast bomber.
Split into simpler sentences: The M.39B Libellula (from Libellulidae, the taxonomic name for dragonflies) was a tandem wing research aircraft built by Miles Aircraft; a scale version of a proposed bomber. The Miles M.39 was proposed by Miles to meet Air Ministry specification B.11/41 for a fast bomber.