Piel was born in Paris, the son of an aeronautical carpenter. One of the best known French designers of light aircraft, over the years, Piel designed several single and two seat aeroplanes, the Emeraude and Diamant being the best known. His first amateur design was adapted from the Mignet Pou du Ciel. Designated CP10, this aircraft, begun in 1943, was only ever a prototype. It crashed in 1949 after only 5h30m flight time. Piel himself was piloting and was lucky to escape from the accident. Piel worked for a variety of French aeronautical companies as a designer. In 1948, he went to work with the Boisavia company where his professional career in aircraft design began. In 1952, he left Boisavia and joined Robert Denize where he designed the CP20, which looked like a miniature Spitfire - its wing shape especially. The CP20 was to be the basis of his subsequent designs, the highly successful CP30 Emeraude. Copavia began to manufacture the Emeraude commercially. Piel then went to work for SCANOR, who also produced Emeraudes. He also sold copies of his plans to amateurs who built their own aeroplanes. The Scintex company was established in 1956 by Jean-Michel Vernhes and set up a production line to make Emeraudes, by now in great demand from French flying clubs and private owners. Initially, Scintex made the standard CP.301A model. In 1959, Piel moved to Scintex and the following year they developed the CP301C variant, which had a sliding canopy instead of the upward-opening doors of the earlier model. Scintex also built the Super Emeraude, with an airframe strengthened for aerobatics and a cleaner external design. Most Scintex Emeraudes and Super Emeraudes were built in the Menavia factory at Clermont-Ferrand. Piel later moved to CAARP. In 1965, CAARP was set up by Auguste Mudry, principally as a design bureau using the skills of Piel, Nenad Hrissatovic and Louis de Goncourt. The company originally built CP1310-C3 Super Emeraudes, and went on to make the CP100 and CAP10 derivatives. Other designs from Piel included the CP.60 Diamant, CP.80 racer and CP.150Onyxmicrolight.