Complex sentence: The elevons served in tailless type aircraft both as elevators and ailerons, while split flaps on the downward angled wingtips took the place of a conventional rudder; they were later straightened after that angle proved unnecessary during flight testing.
Split into simpler sentences: The elevons served in tailless type aircraft both as elevators and ailerons, while split flaps on the drooping wingtips took the place of a conventional rudder. These wingtips originally drooped downward but were later straightened after that downward angle proved unnecessary during flight testing.