Brantly Nuts wrote:

There have been at least 2 tip-jet type helicopters to reach type
certification and production.

Sud Ouest So.1221 Djinn, about 150 produced.
http://avia.russian.ee/vertigo/snias_jinn-r.html

Kolibri H-3, about 10 produced.
http://avia.russian.ee/vertigo/nhi_kolibri-r.html

It says version #1 "was written off through ground resonance". Maybe due to
something like a fuel imbalance through the blades, because 2-blade rotors don't
suffer from ground resonance. Do they?