11. One was a modified platform with a prototype system known as " Outlaw Hunter ". 12. UP Aerospace and the New Mexico location were chosen to aid in testing prototype systems . 13. With other improvements, a full prototype system was first tested at sea in April 1937. 14. The first prototype system was crude, and its original clutch pack controller was a rheostat. 15. A prototype system will start with six LCD screens assembled to form a 3-by-6-foot display. 16. Everything looks ready to build the prototype system . 17. A prototype system was built south of Berlin, known as the "'Tremmen Radar Tower " '. 18. The main prototype system for intercepting enemy warheads failed one test and only partially passed another. 19. In 2014 researchers demonstrated a prototype system that uses copper electrodes and ammonia as the electrolyte. 20. Work then began on a prototype system .