SASless
A brilliant find of a document published in 1969. There are numerous caveats in the document about the test conditions and that the results should not be applied to any other type of helicopter. I particularly note that all tests were carried out with forward airspeed and that the collective was lowered and rotor speed increased in the final stages of the descent to complete the landing.
The purpose of the test appears to have been an attempt to so whether the published manufacturers figures for autorotational glide could be improved upon. The answer was a tentative 'yes'.
The forward speed of the helicopter would have provided some lift and the apparent wind direction through the rotor disc would have been angled, so rotor speeds lower than those normally associated with the onset of rotor stall in a vertical descent could be attained without the helicopter falling from the sky. The vibration and buffeting effects described in the text clearly indicate that the tests were carried out right at the edge of what could be achieved.
Attempts to stretch a glide in any aircraft, fixed or rotary wing, rarely end well. It is however a wonderful tribute to the bravery of the pilot(s) who carried out these tests and proof that there is a bit of latitude in the manufacturers published figures if you have the skills to stretch the limits and the nature of the circumstances absolutely demand you take the risk.
Absolutely fascinating!