hotzenplotz
The Flettner Fl 282 was one of the very earliest helicopters. It is reported that the maximum speed of the Flettner was 93 mph, where as the maximum speed of the Sikorsky R-4B was 75 mph.
Later, Charles Kaman left United Technologies, and with $10,000.00 he started to develop a helicopter. I suspect that he could not compete head-to-head with the advantages that Sikorsky had, and he therefore went after a niche market.
It can be argued that Kaman did not advance the intermeshing configuration when he replaced Flettner's rotor heads with simplistic teetering heads.
IMHO,
Kellett was headed in the right direction. He wanted to develop a rigid 3-bladed intermeshing helicopter. Unfortunately, the death of his test pilot, due the failure of a control linkage, apparently ended his chances of getting the one million dollars that was needed to continue this development. His own death a year later would have brought final closure to his aspirations.
This web page may be of interest.
Intermeshing Configuration - Concerns
Dave