Peter J. Papadakos compound helicopter design, 1953:

http://www.google.com/patents/USD168652

David F. Gebhard / Edward W. Strong single-seat coaxial-rotor helicopter design, 1954:

http://www.google.com/patents/USD172467

Peter J. Papadakos early design for the Gyroliner, 1954:

http://www.google.com/patents/USD172721

Peter J. Papadakos coaxial-rotor helicopter design, 1955:

http://www.google.com/patents/USD175852

Peter J. Papadakos original GCA-35 design, 1956:

http://www.google.com/patents/USD177425

Peter J. Papadakos coaxial-rotor design (GCA-33?), 1956:

http://www.google.com/patents/USD177427

Peter J. Papadakos 1957 design (I presume is a heavy-lifter):

http://www.google.com/patents/USD180958