Complex sentence: Both wings were in two parts and had blunted rectangular plans, built around two spars with dural skin around the leading edges; the rest of the surfaces were fabric covered, including the full-span ailerons which were mounted on the upper wing only.
Split into simpler sentences: Both wings were in two parts and had blunted rectangular plans. They were built around two spars with dural skin around the leading edges; the rest of the surfaces were fabric covered, including the full-span ailerons which were mounted on the upper wing only.