Kaman proposed the Model K-20 to fulfill the light utility role for the US Navy in 1957 and won! The Kaman design featured four blades on the main rotor and three blades on the tail rotor with a single General Electric T58-8F turboshaft engine located above the cabin. Kaman built four YHU2K-1 Seasprite prototypes in 1958-59. These were redesignated as YUH-2A in 1962. 
List of Operators of Kaman YHU2K-1 | |
| From | Organisation with model YHU2K-1 | |||||
| 1962 |
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| Construction Numbers on database of YHU2K-1 | ||||||
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Construction Numbers | Help Us | |
| C/N | Year | History | |
| 1 | 1959 |  147202 : Kaman K-20 Seasprite, c/n 1, ff 02Jul59; del USN as YUH+ | |
| 2 | 1959 | 147203 : Kaman K-20 Seasprite, c/n 2, ff ?; del USN as YUH2K-1, + Mar65 conv to UH-2B | |
 | 3 | 1959 | 147204 : Kaman K-20 Seasprite, c/n 3, ff?; del USN as YUH2K-1, 1+ 1963 the third Seasprite prototype pictured during ditc+ Mar65 conv to UH-2B; May68 conv to NUH-2B |
| 4 | 1959 | 147205 : Kaman K-20 Seasprite, c/n 4, ff?; del USN as YUH2K-1, 1+ |