The United States Navy provided technical expertise to assist the Army in evaluating the design proposals. In October 1961, the Army selected three of the designs for a flight evaluation. Bell's D-250 design was recommended by the Army team and designated the YHO-4 (later YOH-4), Hiller's Model 1100 was recommended by the Navy team and became the YHO-5 (later YOH-5), and Hughes' Model 369 was added to the competition and became the YHO-6 (later YOH-6). Each manufacturer submitted 5 test and evaluation prototypes of their designs to the Army for flight test evaluation at Camp Rucker, Alabama.