The previously mentioned booklet is not on the Nagler. It is a 139-page report done for the United States Naval Academy in 1977. It is entitled 'Single Bladed Torqueless Helicopter Design'
The first idea was
Forces on a Rigid Rotor . The intent was to have the vertical component of centrifugal force balance the lift of the rotor blade. The coning angle was 9.34-degrees and the feathering axis looks to be at 5-10% of chord. Wind tunnel tests were done on a model.
"When cyclic control was applied, the rotor blades would become violently unstable."
Two other ideas were tried and the third one apparently worked; at least it worked on a model.
It appears that no consideration was given to vibration.