Walter Johnson was a scientist who worked with Project Cadmus, and was a member of the original Newsboy Legion, who also worked at Cadmus.
The Pre-Crisis Walter was created by Jack Kirby.
The Post-Crisis Walter was created by Roger Stern and Ron Frenz.
Flip was very into scuba diving, which is how he acquired the nickname "Flipper Dipper", later shortened to "Flip". He had a son, Flip, who was nearly identical to himself. It was later revealed that this son was actually a clone created by Cadmus.