Here's a poser: I've got a friend working on an electronic constant speed
unit for NSI VP props.
It will work just like a standard CSU when switched on (off will revert to
manual blade pitch control) but it is possible to add some features to
reduce pilot workload and/or save his bacon when he/she cocks it up
-typically opening the throttle before increasing the rpm, sending MP into
the detonation zone.
914's are protected (MP is limited according to rpm via electronic
wastegate control) but 912's and other engines are not.
We have decided to stick to a relatively simple system on cost grounds
-meaning inputs will be limited to throttle position, rpm, and perhaps
manifold pressure for unsophisticated (!) engines.
The question is, what laws govern CSU behavior?
My preference (at the moment) is a very simple system: -"manual" constant
speed setting via a switch on the throttle (just like a prop lever) and two
trip switches at, say, the 20% and 90% throttle positions that will reset
the target rpm to max -so that pushing the throttle forwards will
automatically fine off the prop to reduce the chance of detonation, and
pulling the throttle right back will prepare you for a go-around, and put
the prop in air-brake mode.
It is possible to get more or less sophisticated than this. Any ideas?
Miles
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