Good day Greg Vos, I feel your breadth and depth of experience can be an asset to the Rotary Wing Forum and I hope this will not diminish your willingness to contribute and you will take it as intended.
In my opinion part of how the Rotary Wing Forum works is people ask questions, questions get answered and sometimes the wrong answers get corrected.
I have learned a lot here through this process.
This thread is particularly interesting as it was started by someone who understands testing and he presented some interesting test results complete with quantifying the benefit and recognizing the risks.
I consider jm-urbani a friend and have found him receptive to input.
English is not his first language and sometimes I find the words he uses confusing.
He has a relatively narrow range of experience and I find it is useful to frame his posts inside that experience. Short, bumpy grass strips in aircraft of innovative design outside of most general aviation.
Just as my responses need to be framed as a flight instructor in the USA who usually teaches on a familiar eight thousand foot runway with an operating control tower and scheduled airlines.
I find when people refer to me or my friends in pejorative terms I am inclined to discount their contribution to the Rotary Wing Forum.
Vance your responses in general are well thought out and never matter of fact, your a respected flight instructor who operates a very powerful Machine, if I were to research your posts and ideas as you put them out in a constructive way, and yet leave the door open for practical debate.
some clearly academic individuals are not as polite and are very matter of fact, have few flight hours or type ratings to base their sometime biased opinions with?
this thread was about - does a higher pre rotate speed aid performance take off?
finaly it was agreed after some banter that it does not, this happened while I was out today doing some practical tests, myself only reading this response on arrival at home,
my tests today are in line with your comments and with the opening posts yet I have been subjected to countless ( yet very well produced complex theories)
I am always open to improvements and new ideas just because I don’t agree does not mean I don’t appreciate its merit
for the record today pre rotate and take off same plane same MAUW Zero relevant wind QNH 400 Ft OAT 24
150 Rrpm
170 Rrpm
200 Rrpm
260 Rrpm
my distance to 50ft in runway length was almost identical
I am by no means a scientist but these were my actual flight tests done with one gyro all within 2 hours, while I accept that some clever people can add formulas and Complex models and they can discredit actual exp with calculations these were my findings and I am satisfied that a higher pre rote adds little advantage and will only serve to wear the mechanism.
in the above if we are going to be critical the only variable is the lowering weight in fuel spend for the flights