Complex sentence: He concluded that a series of small aerofoils contained within a normal wing section would have improved low-seed characteristics, and rigged up a primitive flow-visualiation rig using a fan and cigarette smoke to confirm his ideas.
Split into simpler sentences: He concluded that a series of small aerofoils contained within a normal wing section would possess improved low-speed characteristics. He rigged up a primitive flow-visualiation rig using a fan and cigarette smoke to confirm his ideas.