Well done Slb. That's the very video that I lifted my picture from. I was going to recommend the video too. A must-watch for anyone interested in helicopters.
The helicopter I flew was the Bell 47, which was developed from the Model 30. I couldn't find any reference to the missing numbers 31 to 46. Can anyone shed any light on that mystery?
The narrator of the video, Bartram Kelly, was the longtime Bell chief engineer, responsible for many of that company's significant helicopters:
https://airandspace.si.edu/collectio...ries-1941-1980
Slb has control.