Thanks for all the interest in this folks.
Quote :
Amber 1 "If you did it properly and at the right speed, the props would spool all the way up with no "dip". Most people got the hang of it but some never did!"
Sounds as if this might be the answer. I can see now (and I've tried to represent it on the plot below) that a slow throttle advance (red) might cause the dip, and how a slightly smarter PL advance (green) might avoid the kink in the speed governor line. However, a faster advance would give a lazier thrust response with the props staying in fine (?), trying to achieve the demanded speed - thus not giving much thrust increase until the end of the transient when they eventually 'bite' to catch the speed (with a bit/lot of overshoot perhaps). I presume a very fast PL slam would have a similar profile in terms of N vs time.
I guess this 'fast slam' response (blue and orange) is not particularly pleasant. The green response is presumably what we are after, where there's a nice smooth rate of change of thrust.
I'm sure I haven't got the shapes quite right - but in principle ??
It seems those 80's pilots just got better at getting the optimum response - or maybe those Viscounts just did it themselves - I remember one pilot saying they knew their own way home! Though, it is still compatible with
Chris Scott's observations that someone used to pistons (e.g. those 70's pilots perhaps) might be a tad slower with the throttles than a pure-bred Darter.
Hey
Zooker - I'll start a thread in Nostalgia to swap memories of EMA spotting in the 70's ...
