sentences:  Its service sponsors pulled out of the program one by one, and it eventually ended due to a lack of interest after demonstrating its capabilities successfully.In 1959 the United States Army, Navy and Air Force began work on the development of a prototype V/STOL aircraft that could augment helicopters in transport-type missions.Specifically they were interested in designs with longer range and higher speeds than existing helicopters, in order to support operations over longer distances, or in the case of the United States Marine Corps, from further offshore.