High Quality Content by WIKIPEDIA articles! The Castel-Mauboussin CM.7 was a high performance sailplane built in France in 1948 and used to establish a large number of altitude and duration records into the early 1950s. Conceived of by designer Robert Castello at his home in 1942, it was not until after the war that he had the opportunity to actually build it. It was a two-seat aircraft with a gull wing and conventional empennage.