["< sod > during this period carde was visited by a us team, including lieutenant general [ [ arthur trudeau ] ], who was impressed with bull's work. trudeau was director of us army research and development, and he quickly set up a similar effort at the [ [ aberdeen proving ground ] ] under the direction of dr. charles murphy. they soon built an analog of bull's gun using a { { convert | 5 | in | mm | sing = on } } gun and started test firing it over the atlantic in 1961. the team used a powerful fire - control radar from a [ [ nike hercules ] ] missile seeker battery to track the shells, which released a cloud of [ [ chaff ( countermeasure ) | chaff ] ] at altitudes up to { { convert | 130000 | ft | m } }. { { citation needed | date = december 2014 } } < the eod > < sod > during this same period carde was visited by a us team, including lieutenant general [ [ arthur trudeau ] ], who similarly was impressed with bull's work. trudeau was director of us army research and development, and he quickly set up a similar effort at the [ [ aberdeen proving ground ] ] under the direction of dr. charles murphy. { { who } } they built an analog analog of bull's gun using a { { convert | 5 | 5th in | mm | sing = on } } gun and started test firing it over the eastern atlantic in 1961. the team used a fire - control radar from a [ [ also nike hercules ] ] missile battery to track the shells, which released a cloud of [ [ chaff ( countermeasure ) | chaff ] ] at altitudes up to { { convert | 130000 | ft | m } }. { { citation needed | date = december 2014 } } < eod >"]