Two years ago Arplast tested a sophisticated Constant Speed control unit for
their electrically adjusted prop. Like Miles said it is not a simple task.
Although the design worked it was plagued by over-run and hunting problems.
Arguably the unit was too sophisticated sensing many engine parameters in
addition to RPM.
As you can imagine they have not stood still and hope to be in a position to
offer a CS control before too long. Price has not been confirmed but it is
expected to add around 650 US dollars to the existing VP price of 2700 US
dollars. One Europa customer with an Xess has recently tried an Arplast
spinner originally designed for the Pulsar and says it is a good match. The
spinner comes pre cut and pre drilled with Carbon front plate and rear
aluminium cover. Fitting adds around 15 minutes to the time it takes to fit
the prop.
Jerry Davis
Flying Hi - Wish I was
jerry@flyinghi.demon.co.uk
-----Original Message-----
From: Miles McCallum <milesm@avnet.co.uk>
Date: 23 December 1998 09:18
Subject: Constant Speed props
For those out there that are waiting for a real constant speed unit for
electric VP props, there is one in the pipeline for next year: I kicked off
a project with a friend of mine (an electronics engineer) and we have just
completed a "test" unit, to be flown in January.
Electric CSU's are not as simple as you might imagine - factors such
as relay response times and hub cycle times (ie. from fine to coarse) all
throw a spanner in the works, and to refine our design, we have been forced
to build a multi-variable unit that will fly for no more than an hour or two
as a data gatherer: after that, we shall build a "proper" ECSU -probably a
digital one as it won't drift out of calibration and hopefully have them for
sale late '99. It appears that they will be usable on most prop/engine
combinations with minor tweaks: the first probably being Rotax/NSI and
Rotax/Arplast. Cost has yet to be worked out, but the target is under 500.
The control format we are looking at currently is manual pitch
change -as they are now- with an "rpm capture button". After that we shall
be investigating something a bit more sophisticated -perhaps with automatic
mode selection linked to MAP -something along the lines of TO/Ldg and Cruise
settings....
All the best,
Miles
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