Allen Epps wrote
This the S-1 video through the wave you were looking at?

http://tinyurl.com/jjjo5

What is (was) an S-1?

From the web:

The skipping of the P-1 designation in the 1962 Joint designation scheme
was most likely due to the fact that it was convenient to redesignate the
P2V, P3V, P4Y, and P5M to P-2, P-3, P-4, and P-5, respectively. 28. Similar
to note 27, the S-1 designation was most likely skipped out of the
convenience of renaming the S2F to S-2 and continuing from there.

Bob Moore
S-2F NAS Kingsville 1959