Everyone seems to be forgetting that the 914 Rotax already has redundant
electrical systems. It has an alternator and it has a magneto that will
operate the fuel pump and minimal electrics in the event of alternator
failure. Lest we forget the battery which will usually (if you are aware of
the failure and conserve juice) outlast your fuel supply. I have flown over
some of the worst terrain in the U.S. (the rockies) and my last worry is
the electric system in a Rotax powered aircraft. I would be more concerned
with fuel system redundancy.
Jim Thursby
-----Original Message-----
From: owner-europa@post.aviators.net
Subject: Re: Looking down the road at batteries
Quoting david joyce <davidjoyce@beeb.net>:
> I am a bit confused about the whole notion of needing two batteries for
> a 914 installation. The Europa manual wiring diagram doesn't show it or
> mention it,
> and I have fitted just the one (Odyssey) battery in my innocence!
The 914 is totally dependent upon electrical power to keep the propeller
rotating due to the fact that it doesn't have a mechanical pump. Some
builders,
myself including, have implemented redundant electrical systems to keep the
second pump operating in the event of a failure of the primary electrical
system.
This redundancy can take several forms... from Bub Nuckoll's essential bus
methodology which has a single battery but draws power for essential
services
prior to the master breaker ... to having a single alternator still but dual
batteries ... right through to implementing a second alternator/generator
with
a second battery.
The Europa demonstrators flying with 914s have flown many hundreds of hours
without a redundant electrical system as have many more 914 powered craft. A
redundant system is not essential with the 914, it just all depends on how
paranoid you are.
I went for a fully redundant system as the terrain in New Zealand means that
I
frequently fly over dense and very rugged subtropical bush and I want the
cooling fan at the front to keep operating over that sort of country.
Tony
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