. . "2008-02-11Z"^^ . "Frank Piasecki"@en . . "American aerospace engineer" . "Frank Piasecki (/pi\u02D0\u0259\u02C8s\u025Bki/ pee-\u0259-SEK-ee; Polish: [pja\u02C8s\u025Btski]; October 24, 1919 \u2013 February 11, 2008) was an American engineer and helicopter aviation pioneer. Piasecki pioneered tandem rotor helicopter designs and created the compound helicopter concept of vectored thrust using a ducted propeller."@en . "1919-10-24Z"^^ . . . . . "2008Z"^^ . "1919Z"^^ . "Piasecki, Frank"@en . .