Design and Performance Study of the Spanish Helicopter Libélula Española

This paper is the second on a series of two papers covering the history and potential performance of the first Spanish designed and built conventional helicopter. The first paper covered the life and work of Federico Cantero Villamil, and a review of Cantero Villamil's design in the context of the "State-of-the-Art" immediately after World War II. The first paper was presented at the AHS 69th Annual Forum (May 2012). Federico Cantero Villamil was a Spanish helicopter pioneer; largely responsible for the design, assembly and possible ground testing of the first conventional helicopter manufactured in Spain. This paper reviews the design details of the Libélula Española and the potential performance of the machine as built by Cantero Villamil and his associates prior to and after the Spanish Civil War. The work herein is also a continuation of the work started by the Spanish aeronautical engineer and Professor Jóse Luis López Ruiz in the performance analysis of Cantero Villamil's design. López Ruiz's work was never published; but his results will be presented here for reference. The results will show how the Libélula Española could have not hovered in or out of ground effect with the powerplant selected for the final design.