Hi Paul,
THANKS! Wow, that's quite a detailed load analysis. I can see why you needed
it. It seems that the available Mega-micro (heehee) Watts available from the
Rotax generator are being well used in most modes of flight. I especially
like the slight rest it gets during cruise, ensuring it can top off the
batteries....and possibly lowering the chance of a failure during this phase
of flight.
Looking at the spreadsheet, I can't help but wonder if there is a need (or
at least used to be..before the changes) for a slightly bigger battery
capacity to help handle the load when the plane isn't at high rpm? Of
course, experience is what matters. If you can recall, what battery size is
working for you?
One side note: Over a decade ago, in order to save a few $$, I replaced the
normal extra-capacity battery on my car (they are quite a bit larger than
the normal size), with one that was smaller...and it kept leaving me
stranded during the winter when running the accessories like fan, electric
window heaters, etc. Granted, I was running the car at idle for periods of
about a half hour, to try to keep warm. I replaced it back to the beefier
battery rather quickly, and all starting problems went away. Of course,
there is no penalty of bigger batteries in a ground-bound vehicle and only a
last resort in an airplane. :)
Hmm.. some HAVE paid more attention to the weight during the build, and
still end up bloated.. 860 is not too bad, IMO.
I'll be trying to use lower power items, such as external LED lights and
EFIS. Since none of them pass Burt Rutans qualification of staying in the
air when tossed there, I will now be adding helium-balloon ballast to the
ship to compensate for it. :)
Thanks again for the detail,
Greg
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Paul McAllister
Sent: Sunday, January 26, 2014 11:42 AM
Subject: RE: Europa-List: Cowl mods for front belt driven alternator
Greg,
I echo David's thoughts on this. With the right design choices it is easy to
stay well within the electrical capacity of the standard Rotax. Modern
avionics, EFIS, LED position lights & strobes do not draw much current.
Attached is the load analysis I did for my aircraft in 2004. I have not
updated it since then but LED strobes, landing lights and low draw current
contactors make it possible to have an even lower electrical load during
cruise.
My 914 XS + Airmaster came in at 860 lb. Over the years I have taken weight
out by removing the vacuum instrument system and small tweaks in other
area's but I sure wish I had paid much more attention to this during the
build.
My favorite comment from Burt Rutan was, "If you are thinking of putting
something on your airplane, first toss it in the air. If it doesn't stay
there by itself then don't put it on."
Cheers, Paul
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