As the United States marks its 250th anniversary, WTOP presents “250 Years of America,” a multipart series examining the innovations, breakthroughs and pivotal moments that have shaped the nation since 1776. HII is proud to partner with WTOP to bring you this series. For most of American military history, designing a new weapon system was a slow, expensive, and often cumbersome process. Engineers worked from paper drawings. Scale models were built and tested.