Today's Message Index:
----------------------
1. 08:37 AM - Re: 914 Alternator Options (N6ZY)
2. 10:27 AM - Re: Re: 914 Alternator Options (Kevin Klinefelter)
3. 07:56 PM - Re: Rotax 912 UL alternator drop-out (FLYaDIVE)
Message 1
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| Subject: | Re: 914 Alternator Options |
Thanks to all who responded to my original post about Rotax alternators. I think
that I will try using just the Rotax generator at first. I was put off by
the Rotax statement that the fuel pumps etc can take up to 8 amps, but it appears
that this is too pessimistic. Jim, your set up sounds very similar to mine.
Have you also fitted an autopilot, as these can take quite a bit of power
when operating?
I would also be interested in the diode mod to the Ducatti regulator. Could you
please either post it here, or email it to me? I will probably cover the regulator
with a cooling shroud as well.
Jerry
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=406447#406447
Message 2
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| Subject: | Re: 914 Alternator Options |
Consider mounting the regulator on the passenger footwell front, inside the plenum
for the air filter. Should stay nice and cool in there.
Kevin
On Aug 11, 2013, at 8:37 AM, "N6ZY" <jffisher@gmail.com> wrote:
>
> Thanks to all who responded to my original post about Rotax alternators. I think
that I will try using just the Rotax generator at first. I was put off by
the Rotax statement that the fuel pumps etc can take up to 8 amps, but it appears
that this is too pessimistic. Jim, your set up sounds very similar to mine.
Have you also fitted an autopilot, as these can take quite a bit of power
when operating?
>
> I would also be interested in the diode mod to the Ducatti regulator. Could
you please either post it here, or email it to me? I will probably cover the
regulator with a cooling shroud as well.
>
> Jerry
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=406447#406447
>
>
>
>
>
>
>
>
>
>
Message 3
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| Subject: | Re: Rotax 912 UL alternator drop-out |
Rich:
You almost had me with your first statements. But, after reading the rest
of your email I realized you are misinformed That's OK, many a person
confuse things such as you did.
Lets cover some basics of wire and insulation and safety.
1 - What determines the amperage carrying capabilities of a wire?
Your answer was the wire size. NOT completely true. LQQk up wire size and
note that the amperage rating is DIFFERENT for the same wire with DIFFERENT
insulation. WHY?
Think of it this way: What is the FIRST thing to FAIL in a excessive
current situation? It is NOT the wire... It is the INSULATION. Ergo,
Insulation is the controlling factor.
Remember this and you will stump 99.67% of the electrical engineers out
there.
2 - Wire - As in the copper wire you are thinking about is rated in Square
Mills. But, it is easier to convert it to a easy number to deal with know
as AWG (American Wire Gauge) or BWG (British Wire Gauge). But, remember it
is the Square Mills and not even the copper.
3 - YES - Ty-wraps and Lacing Cord can cut into ALL insulations and that is
why a sheth is recommended in some situations (See AC43-13) but the
REAL culprit is the INSTALLER. The inexperienced installer does not have
the proper tool to install the Ty-wrap. The Proper tool is required to
make sure the proper tension is applied to the Ty-wrap and the tool has to
be calibrated. MANY an installer does not make the Ty-wrap tight enough
and that leads to vibration - Vibration leads to the slow cutting into the
insulation.
Along with vibration is improper spacing of the Ty-wraps.
Now, some may think that OVER tightening would be the cause but that is not
the situation as proven by ASTM testing.
Next is the Lacing Cord - Well, for years Mill Specs has tried to establish
a testing method to identify good lacing, but all have FAILED! There is no
way to verify how well a bundle is laced - - - How tight, how loose. So
the best they were able to do is to LQQK at it. Someone came up with the
idea of using a tapered pin to slide between the wires and the lacing...
NOPE! That did not work either. LQQK at it and the years of
practical experience will tell the experienced eye what is good or not.
Yet! The spacing of the lacing and the type of knot is covered in
AC43-13.
4 - HUGE - Fupa Rich. You NEVER want to use PVC wire for a plane. Wait
for it... Wait for it... You will argue that your plane is experimental
and you can do whatever you want.
Well, that is why you have a placard in your plane that states: This
aircraft is amature built and does not comply with current FAA standards of
standard aircraft.
PVC melts at a lower temperature than Teflon/Tefzel - AND - it is NOT
self-extinguishing - AND - It puts out hazardous fumes.
That is why it is not recommended for aviation. Again AC43-13.
5 - SO why use Teflon/Tefzel?
Because of engineering/design reasons (as you mentioned) - Thinner and
Lighter wires can be use, which allows smaller access points and less
weight and the pull strength of the wire increases also. And MORE
amperage... Not "slightly more" - Significantly more.
Look up the charts - In some cases the amperage DOUBLES with Teflon/Tefzel
insulation.
6 - Lastly - "Last, Teflon wire insulation has a problem and that is that
it is soft." Sorry Rich - You have things confused... It is NOT soft and
that is the problem. It is hard, requires a larger bend radius and when
exposed to years of service or in the sun the very outer coating dries up
and cracks which becomes abrasive. The outer coating is used for marking
the wire as very few things stick to Teflon/Tefzel. Running Teflon/Tefzel
wire requires proper securing of the wire bundles. This is because even if
the very outer coating is not dried and cracked it is still very abrasive
against itself.
7 - Oh, I've been using the terms Teflon/Tefzel as interchangeable. Not
really - Teflon has been removed and replaced by Tefzel. There were
some chemistry issues that I do not recall. Yet, for most of us - When the
term Teflon wire comes up everyone knows it is Tefzel. Sort of like
Tissues and Kleanx.
BTW - You don't use a VOM to test for insulation. You use a MEGGER.
Rich said: "For that reason alone I would not recommend its use in an
aircraft." And Rich, I would recommend that you read AC43-13 - Again.
*Barry*
On Fri, Aug 9, 2013 at 5:08 PM, Richard Girard <aslsa.rng@gmail.com> wrote:
> Barry, Teflon may be a wonder product and a by product of the Manhattan
> Program to develop the "Bomb", but it will not carry electricity. I have a
> block in the shop that I tested with a VOM. It had infinite resistance and
> a power supply connected across it showed zero voltage coming through the
> block.
> Perhaps you were referring to the insulation used on COPPER wire? If that
> is the case WIRE size is WIRE size and the ability of the WIRE to allow
> electrons to do what they do, flow, cloud, or kill Schroedinger's cat, does
> not depend one whit on the insulation on the WIRE. The gage of WIRE is what
> determines its ability to handle amperage. Too much amperage passed though
> a too small wire makes what is known as a fusible link, perhaps not by
> design or intent, but certainly in practice. The insulation may make it
> possible to carry slightly more amperage without the INSULATION melting and
> the INSULATION type may allow for great weight savings, say Tefzel vs. PVC
> but again it's the COPPER WIRE that does the job and there are hundreds of
> thousands of aircraft and millions of automobiles that have rubber
> encapsulated cotton braid, PVC, Tefzel and other insulations that are
> flying and rolling in perfect safety. The important thing is to use the
> correct gage of WIRE for the circuit capacity and craft it to eliminate
> places that might cause the insulation to be penetrated and short the wire
> to ground.
> Last, Teflon wire insulation has a problem and that is that it is soft.
> Things like nylon ties or even waxed cotton wire lacing will cause it to
> extrude out from under the tie and create a short. For that reason alone I
> would not recommend its use in an aircraft.
>
> Rick Girard
> do not archive
>
>
> On Fri, Aug 9, 2013 at 7:32 AM, FLYaDIVE <flyadive@gmail.com> wrote:
>
>> Hi Paul:
>>
>> Sounds like you have a gorgeous plane.
>> For a standard and 99.976% of the different types of batteries to charge
>> you MUST keep the charge voltage between 13.8 to 14.2 VDC. Over 14.2 you
>> start to overheat the battery. Under 13.8 the voltage is not there to
>> remove the oxides for the battery plates.
>> One thing you mentioned perked my ears up - Dual axis autopilot... Now,
>> that is probably the highest single current draw in your plane. Were you
>> in A/P? Did you hit and air bumps? When an A/P has to recover from an air
>> pump the instantaneous current draw goes up sharply. The power is or
>> should be drawn from the battery followed by the replenishment by the
>> charging system. Now, from my reading Rotax has the worst charging system
>> next to Banlon sock rubbing on a wool carpet. But, I would check things
>> such as you mentioned - COOLING - It may be easier to install a small air
>> scoop with a hose or fans (caution- fans have their own current draw) to
>> blow air directly onto the ACU. This is done in quite a few planes where
>> forced air is blown directly onto the radio stack. The other thing I would
>> check is wire gauge size. First off it should be 'Teflon' wire and it is
>> always better to go UP in size. IF the alternator output is rated at 18
>> Amps the wire size should be no smaller than a 10 AWG and I would use 8
>> AWG. This is one case where bigger is better. And weight for such a short
>> run is not an issue. That takes care of the charging requirements. You
>> will have to address the wire sizes for the other electronic equipment.
>> Keep in mind Teflon wires allow you to use smaller gauge sizes. But,
>> HEAT, forces you to use larger gauge sizes.
>> From my Rotax readings - I would say Rotax is not supplying the
>> advertized 18 Amps and it is not in a smooth DC waveform output.
>> Power Reduction Sequence:
>> Least needed First -
>> Cell Phone ;-)
>> iPad ;-)
>> LIGHTS
>> A/P
>> Second Comm Radio
>> Second Nav/GPS
>>
>> The only reasion I mention this is because an IPad under charge would be
>> only about 1 Amp for a dead battery. A cell phone under charge - 0.1 Amp
>> (100 mA). The other items sure can have high draw.
>>
>> Another thought - How warm/hot is the firewall? IF the firewall is
>> warm/hot or if there is dead air under the dash, you may benefit by placing
>> the ACU on stanchions or placing it on a heat sink. A TRICK that I did on
>> my plane: I covered the glareshield with black speaker carpet. This
>> created a heat shield for radio stack by creating a low heat
>> transfer barrier, aluminum and thin leatherette passes the sun's rays/heat
>> very easily. It also added some class to the plane.
>>
>> Good luck,
>>
>> *Barry*
>> On Fri, Aug 9, 2013 at 12:42 AM, Paul Kuntz <paul.r.kuntz@gmail.com>wrote:
>>
>>> I have a homebuilt Pipistrel Sinus with a Rotax 912 UL that I flew to
>>> Oshkosh and back last week. The panel has a dual Dynon Skyview display with
>>> two-axis autopilot, plus radio and transponder. The total electrical load
>>> with everything running is 7 to 8 amps. Occasionally it can go to 10 amps
>>> if I'm charging cell phone and iPad en route. I'm pretty confident that I
>>> have the electrical system wired so that the ammeter is measuring the total
>>> electrical load.
>>>
>>> The alternator dropped out once on the outbound trip, but came back
>>> after removing the iPad charging load. The symptom was a voltage drop from
>>> 13.8 volts to 12.5 volts. On preflight the voltage may read that high for
>>> a minute or so on a freshly-charged battery, but it quickly drops to 12.2
>>> or 12.1 volts. In flight, the voltage would drop to 12.5 volts and stay
>>> there for several minutes. I would think that if the alternator had
>>> failed, I'd see the voltage drop to the same 12.1 volts that I see on
>>> preflight, and keep dropping slowly. I can't see why it would drop to 12.5
>>> volts and stay there, unless the voltage regulator is failing in a way that
>>> I'm not familiar with.
>>>
>>> The alternator dropped out (same symptoms) a few times on the trip back,
>>> but by reducing the load to 3 amps (one Skyview display, radio and
>>> transponder), it stayed on line except for awhile when it seemed that the
>>> mid-day sun shining on the dashboard was adding extra heat behind the
>>> panel. That time we brought it back by directing cool air from a fresh air
>>> vent forward toward the spot where the voltage regulator is mounted inside
>>> the cabin on the back side of the firewall.
>>>
>>> So the problem seems to be heat-related. Does this make sense? The
>>> Rotax alternator is supposed to be rated for 18 amps, and able to handle a
>>> steady load of 14 amps easily. Does the Ducati regulator have a thermal
>>> self-protect cutout? Do I perhaps have a regulator that is ready to fail
>>> completely, or should I just put an avionics cooling fan behind the panel
>>> to get the air moving?Any other ideas?
>>>
>>> Regards,
>>> Paul Kuntz
>>>
>>> *
>>>
>>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
>>> tp://forums.matronics.com
>>> _blank">http://www.matronics.com/contribution
>>> *
>>>
>>>
>> *
>>
>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
>> tp://forums.matronics.com
>> _blank">http://www.matronics.com/contribution
>> *
>>
>>
>
>
> --
> Zulu Delta
> Mk IIIC
> Thanks, Homer GBYM
>
> It isn't necessary to have relatives in Kansas City in order to be unhappy.
> - Groucho Marx
>
> *
>
> *
>
>
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