David,
I agree in principle, about keeping it light....not planning on doing an
extra alternator at the moment, just information gathering in advance for
when the ship has been airborn awhile. For example, in case I ever want to
be IFR-capable...
Just keeping the options open. One can always place a small lightweight
alternator off the back of the crank as well without being too
jelly-bellied..some have done it per the forum.
Besides, in keeping it light now, I'll know what I'm missing later when it
tips the scales a bit more steeply... :)
It looks like your Rotax power source goes a long ways to power your stuff,
and your ship is not gadget-poor by any means. That is good news.
Thanks for the info.
Greg
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of David Joyce
Sent: Sunday, January 26, 2014 6:49 AM
Subject: Re: Europa-List: Cowl mods for front belt driven alternator
--> <davidjoyce@doctors.org.uk>
Greg, there is a bit of a philosophical issue here! Do you want to include
every possible bit of kit and duplicate all important functions with
considerable addition to your overall weight, or do you want to build to the
lowest possible weight whilst including all vital functions.
Flying an overweight plane carries its own performance and safety penalties
which can possibly outweigh the marginal safety gains of the extra kit. When
it was possible to find plane weights on the Europa website (hopefully soon
to be possible again!), it was noticeable that the weights of 914 Europas
varied from under 800lbs to well over 900lbs if my memory serves. That of
course equates to a load capacity for passengers & fuel etc of between 470+
lbs (fairly comfortable) and perhaps 350 lbs.( very thin passengers or no
fuel!). Admittedly in the US you get away with more than 1270 MAUW, but only
at the expense of eroding performance and safety margins.
For what it is worth my standard 914 alternator (&Ducatti regulator)
with Single Odyssey battery (16
amp/hrs) has for 1000+ hrs coped perfectly well with wobbly prop, EFIS,
autopilot, GPS, twin Nav Com, transponder, EMS and both electric fuel pumps
(although of course you only normally have one of them on as each is capable
of supplying more than full power fuel flow)
I would personally follow the build as light as possble approach and
have that little bit of extra power/weight ratio to help you in the dodgy
situations you may possibly unintentionally find yourself in some time down
the line.
Regards, David Joyce, G-XSDJ (833 lbs)
"Greg Fuchs " <gregoryf.flyboy@comcast.net> wrote:
>>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
> To: europa-list
> 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
>>
>><jan_de_jong@casema.nl>
>>
>> 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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