Today's Message Index:
----------------------
1. 06:25 AM - 28 volts vs 14 volts and electronics (Bill Howerton)
2. 06:39 AM - Re: 28 volts vs 14 volts and electronics (Rico Voss)
3. 06:40 AM - Re: 28 volts vs 14 volts and electronics (Benford2@aol.com)
4. 06:53 AM - Re: 28 volts vs 14 volts and electronics (Ron DeWees)
5. 08:28 AM - Re: Fuel Management update (Chesterman Family)
6. 09:07 AM - Re: Zenith-List Digest: 10 Msgs - 01/09/04 (W.R. \)
7. 01:23 PM - Re: 28 volts vs 14 volts and electronics (Ray Montagne)
8. 02:59 PM - Re: Fuel Management update (bryanmmartin@comcast.net)
9. 07:34 PM - Re: Fuel Management update (Chesterman Family)
Message 1
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| Subject: | 28 volts vs 14 volts and electronics |
--> Zenith-List message posted by: "Bill Howerton" <Bill@Howerton.com>
I'm at the point where I need to start making some decisions regarding avionics,
instruments and power. The questions I ask are these:
1. Are there inherent advantages and disadvantages of one over the other
2. Can electronic devices meant for one voltage system be installed on an aircraft
of another with some type of converter?
3. Is there a good place to learn about these issues? ZAC produces a good set
of plans for building an airplane, and the engine manufacturers produce good
documentation on their engines, but what about power?
Please bear in mind, my knowledge of electronics doesn't extend far beyond battery
installation in my kids' toys (I think I've got this '+' an '-' thing down)
but beyond that I'm lost. So I'd appreciate it if after your guffaws of laughter
at my stupid questions, you answered them using very simple terminology
- the fewer syllables the better
Thanks!
Bill Howerton - N714BH
N601XL Corvair
Message 2
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| Subject: | Re: 28 volts vs 14 volts and electronics |
--> Zenith-List message posted by: Rico Voss <vozzen@yahoo.com>
Bill,
I suggest you tap into the Matronics "Aeroeletric-list
". It's moderated by Bob Nuckolls, who has some 30-40
years in the industry. He has written a book (about
$35) that discusses the issues you have brought up,
and contains several sample wiring diagrams of elegant
but simple elec systems for different applications.
Focus is always on reliability. Book is available on
his web site, www.aeroelectric.com, along with much
valuable information and some supplies.
For #2, some devices can tolerate 14 or 28 volts, some
would require a "converter". You'll have to check the
device..
--Rico
--- Bill Howerton <Bill@Howerton.com> wrote:
> --> Zenith-List message posted by: "Bill Howerton"
> <Bill@Howerton.com>
>
> I'm at the point where I need to start making some
> decisions regarding avionics, instruments and power.
> The questions I ask are these:
> 1. Are there inherent advantages and disadvantages
> of one over the other
> 2. Can electronic devices meant for one voltage
> system be installed on an aircraft of another with
> some type of converter?
> 3. Is there a good place to learn about these
> issues?
__________________________________
http://hotjobs.sweepstakes.yahoo.com/signingbonus
Message 3
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| Subject: | Re: 28 volts vs 14 volts and electronics |
--> Zenith-List message posted by: Benford2@aol.com
In a message dated 1/11/2004 7:25:55 AM Mountain Standard Time,
Bill@Howerton.com writes:
>
> Please bear in mind, my knowledge of electronics doesn't extend far beyond
> battery installation in my kids' toys (I think I've got this '+' an '-' thing
> down) but beyond that I'm lost. So I'd appreciate it if after your guffaws
> of laughter at my stupid questions, you answered them using very simple
> terminology - the fewer syllables the better
>
> Thanks!
>
> Bill Howerton - N714BH
> N601XL Corvair
>
Get on the areo electric list. Bob Knuckles is the best !!!!!
Ben Haas N801BH. do not archive
Message 4
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| Subject: | Re: 28 volts vs 14 volts and electronics |
--> Zenith-List message posted by: "Ron DeWees" <rdewees@mindspring.com>
HI Bill,
I will hit a few rough spots in the discussion and let the gurus fill in the
gaps.
One big difference probobly isn't a factor for our small motors like the Zen
aircraft use. 28 volt systems can send larger currents further on smaller
wires than 12 volt systems. If I had a big V8 in front and needed a battery
in the tail for balance I would opt for 28 volts as the cables could be
considerably smaller and therefore lighter. Twice the voltage converts to
half the current for the same power. OTOH, if I had a small 4 or 6 cyl
engine and could mount the battery closeby I wouldn't consider 28 volt
systems. As far as avionics I wouldn't consider mixing one voltage and
another. Keep with the same voltage as the battery. You CAN convert 12
volts to 28 with a solid state inverter but they aren't more than 80 percent
efficient and will consume extra power. If you use 12 volt avionics with a
28 volt system you will need some sort of resistive or electronic voltage
reduction. This produces heat and, again, wastes power. In general my
observation is that larger planes use 28 volt systems and smaller ones use
12. Used prices seem a bit lower for some 28 volt avionics because the
market is a bit smaller.
If all these decisions are yet to be made I would plan on 12 volt system
unless you have serious reason to go 28 volt. 12 volt batteries are
plentiful and battery chargers are cheap.
Just my opinion
ROn DeWees
----- Original Message -----
From: "Bill Howerton" <Bill@Howerton.com>
Subject: Zenith-List: 28 volts vs 14 volts and electronics
Message 5
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| Subject: | Re: Fuel Management update |
--> Zenith-List message posted by: Chesterman Family <chesterman@on.aibn.com>
keep the simple system simple guys
> The designed system works great but any seemingly small change can screw up the
> design.
> I have the header (large) and small wing tanks on my 701 with a 582. since it
is
> a 1996 vintage my header tank has a vented gas cap so extra venting of the header
> tank was unneccessary.
With the new windshield you cannot have the fuel cap and venting is a must but
what
makes you think that the vent has to go up into the wing? Run it down onto the
floor and out under the seat just infront of the landing gear. you are supposed
to
have a drain there anyway.
Now for gravity feed from the wings. If you run fuel lines down the cabin tubes
,
gravity will do its thing but that makes for an ugly system that you must look
at
while flying so most run them down behind the seat as per the plans and back up
to
the tank. This is where gravity won't work on its own since a small amount of fuel
will lay in the bottom of the fuel line under the seat. When you refill the wing
tank the fuel does not have a high enough "weight" to push the fuel in bottom of
the line back up to the header tank so no fuel transfer so there has to be a way
to
get the air out of the line from the wing tank to the floor. Put the drain control
for lowest point of the system in the seat kickplate so it can be operated while
in
flight. On the ground it can be used to drain possible water or the wing tanks
or
bleed the lines on the ground and inflight when switching wing tanks as draining
the first tank will result in another air lock.
The next critical thing is the fuel line from the wings should be routed to and
teed into the header fuel sight guage at the bottom of the sight .Put an on/off
in the dash so you can start and stop the transfer from wing tanks at will. This
lets the bottom header tank on/off the whole sytem to the engine and gascolator
but
more importantly when you are transferring fuel to the header the sight guage fuel
level will push upwards about 5" indicating that fuel is effectively siphoning
into
the header. when the wing tank stops flowing the sight gauge will return to the
level in the header.
I have found that fuel transfers only slightly faster than the engine burns it
so
overfilling is not likely.
One last concern that makes me think the header tank is important is it lets you
run the wing tanks dry for maximum safe fuel useage.
Those of you that are using the big wing tanks. Put the tank on a 45 degree angle
away from the outlet and see how much unuseable fuel you have. even at 1/2 the
angle. You cannot safely fly a left hand circuit on the left wing tank unless it
is
nearly full since the pickup will possibly loose it's prime. It would be sad to
run
out of fuel when your tanks are not empty.
Another advantage of my system is no wing tank gauges are necessary and I can use
just the nose fuel for local flying or either of the wings when flying further
In the interest of letting this subject end I would be glad to continue off the
list for anyone interested.
Dave Chesterman.
1996 701/582 220hrs
made the 13 hr flight to oshkosh in 2001
Message 6
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| Subject: | Re: Zenith-List Digest: 10 Msgs - 01/09/04 |
--> Zenith-List message posted by: "W.R. \"Gig\" Giacona" <wr.giacona@cox-internet.com>
Have you ever visited Eastern Europe? If you want the plane quick this would
be an excellent time. Kit a copy of the January 2004 issue of EAA's
Experimenter.
--> Zenith-List message posted by: "Kurt Johnson" <compair6@earthlink.net>
Hey Fella's,
My father and I are looking at building a 701 this summer. Neither of us
has any experience with building aircraft or working with sheet metal and
rivets. With this in mind; can two men, working 10-12 hours a day, 6 days a
week, finish a complete plane with engine in one month? What things should
we do to prepare for this effort. Obviously trying to get some hands on
with sheet metal work would go a long way. Any advice will be much
appreciated.
Kurt Johnson
---
Message 7
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| Subject: | Re: 28 volts vs 14 volts and electronics |
--> Zenith-List message posted by: Ray Montagne <ac6qj@earthlink.net>
On 1/11/04 6:55 AM, "Ron DeWees" <rdewees@mindspring.com> wrote:
> --> Zenith-List message posted by: "Ron DeWees" <rdewees@mindspring.com>
>
> HI Bill,
> I will hit a few rough spots in the discussion and let the gurus fill in the
> gaps.
> One big difference probobly isn't a factor for our small motors like the Zen
> aircraft use. 28 volt systems can send larger currents further on smaller
> wires than 12 volt systems.
The current capacity on the wire is exactly the same. What is different is
that a device consuming some number of watts will consume half the current
at twice the voltage. For example, a device requiring 1 amp at 12 volts
would consume 12 watts of power. A device consuming 12 watts of power at 24
volts would only require 0.5 amps.
Ray Montagne, Cupertino CA
Message 8
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| Subject: | Re: Fuel Management update |
--> Zenith-List message posted by: bryanmmartin@comcast.net
> --> Zenith-List message posted by: Chesterman Family <chesterman@on.aibn.com>
>
> Now for gravity feed from the wings. If you run fuel lines down the cabin
> tubes, gravity will do its thing but that makes for an ugly system that you
> must look at while flying so most run them down behind the seat as per the
> plans and back up to the tank.
> This is where gravity won't work on its own since a small amount of fuel
> will lay in the bottom of the fuel line under the seat. When you refill the wing
> tank the fuel does not have a high enough "weight" to push the fuel in bottom
of
> the line back up to the header tank so no fuel transfer so there has to be a
way
> to get the air out of the line from the wing tank to the floor.
As long as no point in the transfer lines rises higher than the level
of fuel in the wing tanks and the vent line is clear, there should be
no problem getting fuel to feed to the header tank even with air in the lines.
And you will need a drain at each low point.
>
> One last concern that makes me think the header tank is important is it lets
you
> run the wing tanks dry for maximum safe fuel useage.
> Those of you that are using the big wing tanks. Put the tank on a 45 degree
> angle
> away from the outlet and see how much unuseable fuel you have. even at 1/2 the
> angle. You cannot safely fly a left hand circuit on the left wing tank unless
it
> is
> nearly full since the pickup will possibly loose it's prime.
If you keep your turns coordinated, there should be no problem getting fuel to
flow from the tank even in a steep bank with a low level in the tank. In fact it
will flow better because of the increased G loading. The only time the fuel
level the tank will be at an angle is if you are slipping the plane in on short
final for runway alignment or to lose altitude quicker. At that point
you should have the runway made even if you lose power.
Bryan Martin
Message 9
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| Subject: | Re: Fuel Management update |
--> Zenith-List message posted by: Chesterman Family <chesterman@on.aibn.com>
bryan-- you are wrong
the column of fuel in the wing tank is 6" and the column of unused fuel to be pushed
up to the header tank is about 16". therefore the fuel does not drain. this
is why you have to open the bottom drain the increase the column of fuel which
is air locked to flow down to the floor.
2nd-I will concede on the coordinated turn but you must be a better pilot than
my friend and I as my wing tanks sometime do not completely empty (no problem
for my system) but my friend uses the big tanks (no header, individual feed wing
tanks) and has had the engine quit twice while in level cruise (he thought)
with what he thought was ample fuel.
I am trying to tell you what happens in practice---not theory
dave
bryanmmartin@comcast.net wrote:
> --> Zenith-List message posted by: bryanmmartin@comcast.net
>
> > --> Zenith-List message posted by: Chesterman Family <chesterman@on.aibn.com>
> >
> > Now for gravity feed from the wings. If you run fuel lines down the cabin
> > tubes, gravity will do its thing but that makes for an ugly system that you
> > must look at while flying so most run them down behind the seat as per the
> > plans and back up to the tank.
> > This is where gravity won't work on its own since a small amount of fuel
> > will lay in the bottom of the fuel line under the seat. When you refill the
wing
> > tank the fuel does not have a high enough "weight" to push the fuel in bottom
> of
> > the line back up to the header tank so no fuel transfer so there has to be
a
> way
> > to get the air out of the line from the wing tank to the floor.
>
> As long as no point in the transfer lines rises higher than the level
> of fuel in the wing tanks and the vent line is clear, there should be
> no problem getting fuel to feed to the header tank even with air in the lines.
> And you will need a drain at each low point.
>
> >
> > One last concern that makes me think the header tank is important is it lets
> you
> > run the wing tanks dry for maximum safe fuel useage.
> > Those of you that are using the big wing tanks. Put the tank on a 45 degree
> > angle
> > away from the outlet and see how much unuseable fuel you have. even at 1/2
the
> > angle. You cannot safely fly a left hand circuit on the left wing tank unless
> it
> > is
> > nearly full since the pickup will possibly loose it's prime.
>
> If you keep your turns coordinated, there should be no problem getting fuel to
> flow from the tank even in a steep bank with a low level in the tank. In fact
it will flow better because of the increased G loading. The only time the fuel
> level the tank will be at an angle is if you are slipping the plane in on short
final for runway alignment or to lose altitude quicker. At that point
> you should have the runway made even if you lose power.
>
> Bryan Martin
>
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