While reading the official history of SAC Headquarters for 1961
Link to PDF of the History
I found the following interesting bits
1.) They designated the reconnaissance/strike version of the B-70 the RSB-70, instead of the designator RB-70, you can see this on page 111.
2.) They redesignated the entire reconnaissance/ELINT series of B-47s to non-standard designators for PR reasons; you can see this on page 117:
Link to PDF of the History
I found the following interesting bits
1.) They designated the reconnaissance/strike version of the B-70 the RSB-70, instead of the designator RB-70, you can see this on page 111.
2.) They redesignated the entire reconnaissance/ELINT series of B-47s to non-standard designators for PR reasons; you can see this on page 117:
The R-47s and the E-47s were the old RB-47s redesignated.
The redesignation was necessary to clearly distinguish reconnaissance Stratojets from bombers to lessen the propaganda potential should another one be shot down by the Russians. The modified B-47s were redesignated in August 1961 as follows:
RB-47H to R-47H
RB-47K to R-47K
RB-47E to E-47
ERB-47K to ER-47H