Complex sentence: The Libélula Viblandi, or Libélula Española (Spanish dragonfly) was an early helicopter developed from 1924 by Federico Cantero Villamil, a Spanish civil engineer also known for the dams he constructed and planned along the river Duero.
Split into simpler sentences: The Libélula Viblandi, or Libélula española (Spanish dragonfly) was one of the first helicopters invented 1924. It was developed in the twenties by Federico Cantero Villamil, a Spanish civil engineer also known for the dams he constructed and planned along the river Duero.