PETERSON, Harold W., left, and George Callahan 2 Published on January 4, 2014 in 5 January 1956Full resolution (640 × 440) ← Previous Next → Harold W. Peterson (left) and George Callahan, with the prototype Piasecki YH-16A Turbo Transporter, 50-1270. (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)