A number of respodents to this subject do not seem to fully understand or appreciate the physics associated with the airflow reversal in the rotor in the last moments just prior to touchdown/run-on.
My own view is that ground effect must play some part during the final pitch pull, though I agree with respondents who have stated how difficult it is to quantify just how much (or how little).
One respondent mentioned the flare. The airflow is not reversed in the flare whilst still autorotating, and the physics in this portion of the maneovre should be studied separately.
Comments to all respondents made with respect and courtesy - does anyone disagree with me?
Mike Strother, Leeds