Hello,
It seems to me that the nice and logical distinction that Helmet Fire made between LTA and LTE parallels the one between SWP and VRS:
- Settling with power = you are asking for power you don't have, in a way equivalent to LTA, and
- Vortex ring state = the aerodynamic doughnut can happen to the main rotor, the "usual" VRS, or to the tail rotor, and then it is LTE.
Now, from what I understand, there is another effect, which is due to the main rotor/tail rotor interaction (with vortices being blown from the main to the tail), which Helmet Fire puts in with LTE. For this one I don't see a main rotor equivalent.
Bon vent