<article><hdr>Ground shot of a Douglas BT-1</hdr><body>
<hi style=afpcap>Douglas produced a biplane for the observation role during the mid '20s, with several variants having different designations. The basic XO-2 was subsequently developed into numerous sub-variants, most of which were the result of a different engine fitment or other refinements. 60 production O-2Ks were converted to duel control basic trainers with the designation BT-1 assigned. A flight from Fort Clark, Texas to Kelly Field in September 1935 was the final US Army mission flown by an aircraft fitted with the famous World War One Liberty engine. </hi>
