The Curtiss XO-16 was a conversion of O-11 28-196 when completed with
a 600 hp Curtiss V-1570 Conqueror liquid cooled V-12 engine in place
of the 435hp Liberty V-1650. The XA-5 was the designation assigned to
a proposed attack version of the XO-16. However, the XA-5 was
cancelled before anything could be built.