To: charlie s charlie
What Gaseous said is probably true since Frank Robinson designed the R-22 as a personal helicopter that could be taken from home and return on a trailer or that it could be sheltered in a hangar taking up less space and costing less for that space.
However I personally feel that there were other things that influenced the design.
1) Frank Robinson worked for several helicopter manufacturers prior to making his own design. He couldn't copy the design of his employers so he adapted the basic design (Bell) and in order to keep the weight down he incorporated cone hinges.
2) His patented design was much simpler and the parts count was lower than that of a three-blade design and less costly to build.
