A remote controlled U.S. Navy Kaman HTK-1 helicopter in flight. The pilot was on board for safety reasons.
U.S. Navy
<a rel="nofollow" class="external text" href="http://www.navy.mil/ah_online/department_arch.html">U.S. Navy All Hands magazine</a> <a rel="nofollow" class="external text" href="http://www.navy.mil/ah_online/archpdf/ah195610.pdf">October 1956</a>, p. 11.