>Perhaps in the situation above, it would be prudent for a 914 builder (914
can draw 11 amps on its own with both pumps running) to consider a belt
driven ??
>alternator of 40 amps, and simply redo the cowl front and keep the Rotax as
a backup in case of belt failure.
Bud, or those that know,
At some point, or future avionics upgrade, my ship will likely need the
extra Watts.
Would you care to supply a 'teaser' on the making of the cowl mod? I am
still waiting for my FF package, so don't yet have a handle on how it
integrates with the prop flange, but does the front of the cowl terminate
just behind the prop flange, on the smaller-radius drive tube? Are the
belt-driven alternator components in front of the cowl then, requiring the
cowl front face to be opened up and added to? Is this considered an
extensive change?
Regards,
Greg
_____
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Bud Yerly
Sent: Thursday, January 23, 2014 9:13 PM
Subject: RE: Europa-List: Re: Ducati rectifier/regulators
.....
If you are an amp zealot, but still want an aux fuel pump, pitot heat, 100
watt landing light, strobes, heavy draw radio (Garmin 430 type), Aux Radio,
Mode S transponder continuously working, autopilot, stereo high quality
music system, external power plugs for our phones, I-pads and inflight video
system, the Rotax charging system is not going to hack it.
Perhaps in the situation above, it would be prudent for a 914 builder (914
can draw 11 amps on its own with both pumps running) to consider a belt
driven alternator of 40 amps, and simply redo the cowl front and keep the
Rotax as a backup in case of belt failure.
If you build a 912S airplane with all LED lighting, Garmin 255 or Becker
Com, Simple digital Transponder, Aux Boost, and maybe an autopilot for
cruise only and a paper map, then the Rotax / Ducati should be fine. The
GR6 or SH may be better and longer lasting to boot. In my opinion the Rotax
system can't put out much more than 15 amps or so and as the current
increases, the voltage output starts to diminish (at least it does in my
poor old airplane) .
Just my thoughts.
Bud
> Date: Mon, 20 Jan 2014 16:40:25 +0100
> From: jan_de_jong@casema.nl
> To: europa-list@matronics.com
> Subject: Re: Europa-List: Re: Ducati rectifier/regulators
>
>
> Re two-phase bridge rectifier/regulator.
> The 2 thyristors in the rectifier bridge do not short the AC input or
> "dump" anything.
> On the contrary, they disconnect the DC output from the AC input when
> the output voltage threatens to exceed the set voltage.
> All output current passes through one branch of one diode and one
> thyristor in series half the time and through the other identical branch
> also half the time.
> Heat development is proportional to the output current and the voltage
> drop across a branch.
> Voltage drops increase somewhat with current, so heat development
> increases more than linearly with output current.
> In the Ducati device the diode is reportedly a MR2510 pill (typically
> 0.75V at 10A, 0.8V at 20A), the thyristor can be a 2N6504 (typically
> 1.1V at 10A, 1.3V at 20A).
> So at 10A the two branches of the bridge are each expected to generate
> 0.5 x (7.5 + 11) = 9.25W (total 18.5W) of heat.
> And at 20A the two branches of the bridge are each expected to generate
> 0.5 x (16 + 26) = 21W (total 42W) of heat.
>
> (
> a failure mode for the Ducati device is reportedly the loss of
> continuity of a diode pill attachment through thermal cycling; fitting
> external parallel diodes has been proposed as a solution; replacing the
> whole device seems more sensible
> )
>
> Cheers,
> Jan de Jong
>
&g======================
&g======
>
>
>
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