sentences:  However, for the Marine Corps mission, the requirement stated that the fuel load could be reduced so that the maximum gross weight would not exceed , as long as a radius was maintained.Vought responded with a proposal combining engineering from their own design arm, as well as Ryan and Hiller, who had more extensive helicopter experience.Their proposal won the design contest, and a contract for five prototypes was signed in early 1962 with first flight specified for July 1964.