04/30/2009. This was the last of six PS-2s produced for the USN, serials 9401, 9402, 9614 to 9617. In 1934 they were used in an USN primary flight training experiment in Pensacola, Florida, directed by Captain Ralph S. Barnaby. Two of the gliders were later used by the NACA in a study of ground effect on a towed glider.