Today's Message Index:
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1. 03:19 AM - Re: Re: Jabiru Starter contactor and solenoid (Grant Piper)
2. 07:07 AM - Re: Re: Jabiru Starter contactor and solenoid (Gilles Thesee)
3. 07:42 AM - Re: Jabiru Starter contactor and solenoid (Gilles Thesee)
4. 09:30 AM - Re: Jabiru Starter contactor and solenoid (Paul Mulwitz)
Message 1
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| Subject: | Re: Jabiru Starter contactor and solenoid |
I'm a late starter to this topic, but I applaud Doug's pleas to keep it
simple. Less things, less to go wrong. My RV-4 with Lyc has a Datsun
alternator, Odyssey battery and no lights or gyros at all. It is legal
at that. I do use a Master relay, but eliminated the separate starter
relay when I saw that my starter had a piggyback relay as per a car.
Yes, my starter cable is 'live' all the time the Master is on, but if I
have a short I can isolate it by switching the Master off. Yes, I will
lose all power, but it is a VFR aircraft so that isn't a biggie.
Keep it simple, spend the dollars saved on avgas, and go flying this
year instead of the next.
Grant Piper
RV-4 VH-PIO 260hrs.
SAAA (TC)
----- Original Message -----
From: Kayberg@aol.com
To: jabiruengine-list@matronics.com
Sent: Saturday, December 09, 2006 10:27 AM
Subject: Re: JabiruEngine-List: Re: Jabiru Starter contactor and
solenoid
I suppose I should keep my mouth shut, but in case there are other
folks who are daunted by the diagram Modified Z-16, I want to affirm
your desire for simplicity. I am impressed by the efforts of Vozzen and
Rico. I dont mind the efforts of electical engineers to plan for every
possible failure mode. I understand that some experimental aircraft
builders want to build an electrical system to rival any of the General
Aviation fleet.
But there is another strategy. If you are careful about the avionics
you purchase, use some common sense and dont install a comprehensive
lighting system ( how badly do you want to crash at night? .... if you
dont have lights you wont be tempted..) and are willing to just read
your own voltmeter, you can have a simple system that can be installed
in a few hours instead of a few months.
It is ok to use a couple toggle switches for your ignition kills. It
is ok to just run breaker switches or switch and fuse to a couple
radios. If you keep your electical loads down, then you dont need much
of an alternator. As you may know, if you have too big a load on the
Jabiru alternator, you can crispy the stator. You can add another
seperate alternator, but why would you want to?
The notion of a solonoid operated by a master switch sounds good, but
if the wire or coil in it goes south, so does your electrical power.
That may balance the possiblity of shorting the big wire to the starter
solonoid.
If you are building a small, high performance bird like a Sonex and
want to make it IFR, by all means design and build as complicated an
electrical system as possible. May I suggest autopilot, a Garmin radio
stack, electrical gyros and a seat warmer? The extra time it takes to
build all that will prolong your life just that much longer.
I am just saying that IN MY OPINION, it is perfectly OK to only have a
couple circuits. One for the start, one for the radios and one for a
couple other small things. If you are a bit paranoid, then include a
switch in the charging circuit so you can shut off the alternator power
to the battery if your volt meter gets too high. Hook the power
circuits to the post on the starter solonoid that the big battery cable
goes to...just so it is easier to disconnect the battery. It is true
that if the solonoid sticks, you will have some drama while the starter
twirls the engine until the battery dies...but when is the last time
your car did that to you? It is wired the same way. Just buy a new
start solonoid every 500 hours or so. That should preclude the arcing
from dirt.
Ok, so let the reactions begin. I'm sure I deserve to be flamed.
Doug Koenigsberg
Message 2
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| Subject: | Re: Jabiru Starter contactor and solenoid |
Grant,
> Yes, my starter cable is 'live' all the time the Master is on, but
> if I have a short I can isolate it by switching the Master off. Yes,
> I will lose all power, but it is a VFR aircraft so that isn't a biggie.
Correct. This is how any aircraft should be wired.
>
> Keep it simple, spend the dollars saved on avgas, and go flying this
> year instead of the next.
Perfectly right. The problem is, some builders confuse 'simple' with
over simplistic, or try to take short cuts on safety by 'simplifying'
the thinking process before building.
For those who think the electrical circuit is worth some consideration,
a visit to http://www.aeroelectric.com will prove very informative.
Regards,
Gilles Thesee
Grenoble, France
http://contrails.free.fr
Message 3
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| Subject: | Re: Jabiru Starter contactor and solenoid |
Hi Doug,
> I am the proud USA importer of the French kit airplane, the Sky Ranger!
Yes everyone here knows the Sky Ranger.
> Ranger and a 3300 in a Lightning.
>
> I just run the large power wire about 6" to the starter solenoid. I
> would attached fused or breaker protected circuits from the post there
> to elsewhere. If one of them were to short, I would expect protection
> to kick in or if it shorted on the way to the breaker, I would expect
> the wire to just fry without much damage. The runs are short and the
> firewall penetration carefully protected.
If complexity (and maybe weight) is a consideration, why use breakers at
all ? Fuses would just do, with lower cost, installation complexity and
weight.
>
> I note that the same large 6" wire would go to the master solenoid and
> then another 6" wire would to to the Jab start solenoid. No real
> difference in protection for the large wire. In either case it has a
> 6" unprotected run.
The battery contactor is to be located as close to it's battery as
physically possible. The role isn't to protect wires (they are large,
and won't fry), but to disconnect the ship's circuit from any source of
electricity.
If the component are close together, you may consider a metal strap
instead of a wire. Still simpler.
> But if the master solenoid, which must be continously held in place
> by current were to experience low voltage, coil failure, switch
> failure or a wire break then all power would be lost......unless one
> has a backup circuit that bypasses the master....which is the
> situation I began at.
The goal of the electrical circuit designer is to minimise the fire and
fault hazard.
The only way to experience low voltage is low battery and/or faulty
charging circuit. The engine is not electrically dependent, and I
suppose that in the USA, ultralights only fly day VFR ? No critical
circuit to keep running. So why take shortcuts on safety for fear of
lacking of electricity ?
> I understand that popular aviation thought is in love with the master
> solenoid, but I am wondering if it adds complexity and vulnerability
> to solve an unlikely problem...on very simple light airplanes.
Simplicity should be in the aircraft, not in the designer/builder
efforts in design. It takes much thinking to design a really simple and
reliable aircraft system.
Popular aviation would really benefit from carefully engineered and
crafted systems : I recently had to troubleshoot a poorly wired
ultralight (not a Sky). Really poor craftsmanship from the importer...
> I like them more on GA airplanes with their 60 -100 amp circuits with
> retractable gear, lights, dog polishers and window foggers.
;-)))
>
> ..... Of course a short can cause a fire but there must be
> combustables nearby and the insulation must be combustable. Otherwise
> a brief arc, a brief smell and it is all over.
Yeah, that's what is often experienced in ultralights. Sparcs and arcs,
and flat batteries. Auto PVC spaghetti wire everywhere, control cables
and rods rubbing against structure (yes sir, even on Sky Rangers)
The reputation of sloppy craftsmanship is unfortunately sometimes
deserved...
If I happened to buy an aircraft and experienced even the briefest of
arc ans smell, I'd have some 'interesting' discussion with the seller...
>
> If a starter solenoid actually stuck, it will just keep turning the
> engine untill the battery power is drained or the starter melts
> down. While disconcerting, it would happen on the ground and be over
> quickly. No so if your master solenoid craps out in the air. You
> lose radios, EIS, intercom, flaps and whatever else you power.
You really would shed circuit protection and good wiring practice just
for fear of losing flaps when turning the master off ? Would no flaps on
a Sky Ranger really be a problem ?
BTW, in a car, you also lose many thing when turning the keyswitch off.
Have you considered subscribing to the Aeroelectric List on Matronics ?
Much interesting matters, and opportunity to discuss electrical options
much more in-depth
Best regards,
Gilles
http://contrails.free.fr
Message 4
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| Subject: | Re: Jabiru Starter contactor and solenoid |
Hi Gilles,
The new Light Sport Airplane rule in the USA allows for either
day/VFR or Night and/or IFR operations. Of course, there are extra
equipment requirements for night or IFR operations. It is the Sport
Pilot rule that limits pilots (rather than aircraft) to day/VFR
operations. The much older "Ultralight" in the USA is not worthy of
any serious flight including daytime. I don't think anyone would
consider flying one of those "Flying lawn chairs" at night. Those
"Ultralights" are limited to one seat, 5 gallons of fuel, maximum
empty weight of 254 pounds, and a maximum cruise speed around 60 mph.
I have been following your discussion of the need for the master
contactor on an airplane. I remain unconvinced either way about the
need for this device. It is relatively clear it can be used to deal
with in-flight fires, and it also might be used to make sure all
equipment is really off when the plane is finished for the day.
If there is a switch installed on the battery circuit for all devices
except the starter, then normal sized wiring and switch could be
used. This approach would use a solenoid for the starter connected
in parallel to the battery. The only obvious risk with this approach
is that the starter solenoid gets stuck or activated without the
pilot's desire. This seems unlikely and un-harmful even if it does occur.
Perhaps I am missing something important. It seems that the expense
in cost, weight, and electrical load imposed by the master contactor
is only there to deal with the unlikely problem of a run-away starter solenoid.
Paul
Zodiac XL builder - nearing completion of fuselage
>I suppose that in the USA, ultralights only fly day VFR ?
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