3 side view of the U.S. Navy Piasecki HUP-2 <i>Retriever</i>. The HUP-2 was redesignated UH-25B in 1962.
USN
U.S. Navy Bureau of Aeronautics Standard Aircraft Characteristics <a rel="nofollow" class="external text" href="http://www.alternatewars.com/SAC/HUP-2_Retreiver_SAC_-_1_July_1952.pdf">HUP-2 Retriever</a> available at <a rel="nofollow" class="external text" href="http://www.alternatewars.com">alternatewars.com</a>.