Today's Message Index:
----------------------
1. 04:48 AM - Re: Thermocouples in an ultralight - theory help, (chad-c_sip@stanfordalumni.org)
2. 05:31 AM - Re: Thermocouples in an ultralight - theory (Robert L. Nuckolls, III)
3. 06:20 AM - Re: choosing which loads go on the Main Buss (Dave Morris \)
4. 06:54 AM - Re: Moving Battery and howto (Dave Morris \)
5. 07:06 AM - Re: Moving Battery and howto (Robert L. Nuckolls, III)
6. 07:07 AM - Re: Re: Capacitance style fuel level sensor (Robert L. Nuckolls, III)
7. 07:11 AM - Re: Intercom Wiring (Robert L. Nuckolls, III)
8. 07:13 AM - Re: Re: Capacitance style fuel level sensor (Robert L. Nuckolls, III)
9. 07:30 AM - Re: Battery Testing (Robert L. Nuckolls, III)
10. 07:35 AM - Re: Thermocouples in an ultralight - theory help, (AI Nut)
11. 07:39 AM - Re: Thermocouples in an ultralight - theory help, (AI Nut)
12. 08:26 AM - Re: Intercom Wiring (rv-9a-online)
13. 08:44 AM - 12 volt bus in a 24 volt system (Drdavevk30@aol.com)
14. 09:00 AM - Re: Intercom Wiring (Guy Buchanan)
15. 09:00 AM - Re: Intercom Wiring (Guy Buchanan)
16. 10:10 AM - Re: questions (Robert L. Nuckolls, III)
17. 10:29 AM - Difficulties with AC motor (chad-c_sip@stanfordalumni.org)
18. 10:38 AM - Re: 12 volt bus in a 24 volt system (Joel Jacobs)
19. 11:05 AM - Re: Difficulties with AC motor (Hinde, Frank George (Corvallis))
20. 12:15 PM - Re: Difficulties with AC motor (Matt Prather)
21. 01:26 PM - Re: Difficulties with AC motor (chad-c_sip@stanfordalumni.org)
22. 01:33 PM - Re: Difficulties with AC motor (John Danielson)
23. 03:40 PM - Re: Difficulties with AC motor (Robert L. Nuckolls, III)
24. 03:40 PM - Re: 12 volt bus in a 24 volt system (Robert L. Nuckolls, III)
25. 03:57 PM - Re: Difficulties with AC motor (Hinde, Frank George (Corvallis))
26. 05:03 PM - Re: Difficulties with AC motor (chad-c_sip@stanfordalumni.org)
27. 05:09 PM - Re: Difficulties with AC motor (chad-c_sip@stanfordalumni.org)
28. 05:12 PM - Re: 12 volt bus in a 24 volt system (chad-c_sip@stanfordalumni.org)
29. 05:53 PM - Z-19 vs. Z-14 (Larry E. James)
30. 06:52 PM - 12 volt bus in a 24 volt system (Drdavevk30@aol.com)
31. 07:46 PM - Re: 12 volt bus in a 24 volt system (Eric M. Jones)
32. 09:09 PM - Re: Thermocouples in an ultralight - theory help, (Richard E. Tasker)
33. 10:00 PM - Re: Re: battery maintainer More (Robert L. Nuckolls, III)
Message 1
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please?
| Subject: | Re: Thermocouples in an ultralight - theory help, |
please?
Z-USANET-MsgId: XID948JFiLrr0177X38
--> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
No, I don't believe that's possible. Though the copper junctions with the TC
wires may be at the same temperature, they're not, necessarily, the same
voltage jump/drop at each junction. Instead, run thermocouple extension wire.
It's material designed for each kind of TC that's either got near-zero voltage
or matched voltage changes at each junction but is a whole lot cheaper than
the actual probe wire.
Omega sells a ton of this stuff at:
http://www.omega.com/toc_asp/subsectionSC.asp?subsection=H07&book=Temperature
Good luck.
Chad
Chad Sipperley
Lancair IVP-turbine (under construction)
Phoenix, AZ
------ Original Message ------
From: Richard Riley <richard@RILEY.NET>
Subject: AeroElectric-List: Thermocouples in an ultralight - theory help,
please?
> --> AeroElectric-List message posted by: Richard Riley <richard@riley.net>
>
> I'm installing a 22 hp single cyl 2 stroke in an open frame ultralight.
>
> I'm using a CHT/EGT combo analog gauge. Can I transition from the
> thermocouple wire to copper at the end of the probe wire? Since everything
> is out in the open air, and thus should all be at about the same
temperature?
>
>
>
>
>
>
>
Message 2
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please?@roxy.matronics.com
| Subject: | Re: Thermocouples in an ultralight - theory |
help, please?
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
help, please?
At 10:52 PM 6/8/2005 -0700, you wrote:
>--> AeroElectric-List message posted by: Richard Riley <richard@riley.net>
>
>I'm installing a 22 hp single cyl 2 stroke in an open frame ultralight.
>
>I'm using a CHT/EGT combo analog gauge. Can I transition from the
>thermocouple wire to copper at the end of the probe wire? Since everything
>is out in the open air, and thus should all be at about the same
>temperature?
If you have a stand-alone gage (like View -C- in Figure 14-10
of 'Connection or in:
http://aeroelectric.com/articles/excerpt.pdf
then the instrument is calibrated assuming that the cold
junction occurs inside or at the rear of the instrument.
In an airplane like an ultralight, your supposition that
ambient temperatures at a remote cold junction and at
the instrument will be fairly close is a good one . . .
as long as the remote junction is not exposed to localized
heating from the engine.
The always-proper way to extend thermocouples in any
instrumentation package is with thermocouple wire which
is readily available as cited in another post. In this
case, however, you're not likely to introduce serious
errors by using copper to extend the wires.
Bob . . .
Message 3
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| Subject: | Re: choosing which loads go on the Main Buss |
--> AeroElectric-List message posted by: "Dave Morris \"BigD\"" <BigD@DaveMorris.com>
I'm not going to solve your entire problem, but I can add a data point. I
had this same conundrum, with a battery bus, and e-bus, and a main
bus. This was my thinking.
Look at the devices that have no power switch on them, and that can turn
themselves on and off without your control, such as a tank level dependent
fuel pump. If it is necessary for flight, put it on the e-bus. Otherwise,
put it on the Main bus.
Now look at the devices that have no power switch and must be on all the
time for flight. For example, I have a Rocky Mountain Microencoder. It
has no power switch, so even though I originally thought it was a prime
candidate for the battery bus, I had to put it on the e-bus in order to
shut it off after flight. Same for my GRT EIS.
I have some pitch and roll servos. I can put them on the e-bus, because
*I* control when they are used. In the event of an alternator failure, if
I need the AH kept in reserve, I just don't use the pitch and roll
trim. They don't have to go on the Main bus, because again *I* will just
choose not to use them in a battery-only flight.
I think the purpose of separating the e-bus from the main bus is to be able
to flip a switch, without having to think long and hard about it, and
instantly reduce your battery load and extend your flight. If everything
you have on the Main bus had its own power switch, you could just as easily
just switch OFF everything (there's still the battery contactor current,
but that's another issue) and accomplish the same thing. So think of the
things that you would not mind - instantly and without hesitation - losing,
and put those on the Main bus.
Remember also that - in the event of an alternator outage - you can flip
off the main bus, fly along on the e-bus, and then in your own good time,
switch off all the devices on the main bus that you don't really need, and
occasionally power up the main bus again to operate some piece of equipment
you put on the main bus but that you really want to use. For instance you
could put your COM radio on the main bus and just power it up occasionally
when you need it, with all other main bus equipment switched off.
That's my $0.02 worth.
Dave Morris
At 06:36 PM 6/8/2005, you wrote:
>--> AeroElectric-List message posted by: "Larry E. James" <larry@ncproto.com>
>
>New conundrum. I'm building my load spreadsheet and seeing
>that a lot of pilot choice and procedure enters into the
>decision of where to route certain loads (pieces of
>equipment). Where I'm currently headed is to minimize the
>equipment on the Battery Buss (because it is always on) and
>limit the E-Buss equipment to first 8 amps and second just
>what is necessary to get me down. Everything else goes on
>the Main Buss. Sounds simple, but in the few examples of
>other's Load Analysis I have seen; different thinking is
>evident. What's up ?? Can I get some direction ??
>as always, thanks
>--
>Larry E. James
>Bellevue, WA Harmon Rocket
>
>
Message 4
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| Subject: | Re: Moving Battery and howto |
--> AeroElectric-List message posted by: "Dave Morris \"BigD\"" <BigD@DaveMorris.com>
I bought several of B&C's custom battery cables. You specify the end
terminal size and style and the length of the cable, and they do all the
hard work for you installing the 2 or 4ga terminals. And I'm bolting two
pieces together myself to allow more flexibility in installing the battery.
Dave Morris
At 12:24 AM 6/9/2005, you wrote:
>--> AeroElectric-List message posted by: "Werner Schneider" <glastar@gmx.net>
>
>Should have thought about bolting before; as I reduce the cross section here
>I might expect some warming up of the connection during starting I guess,
>but I will follow this easiest route and butt splice just the battery-bus
>items.
>
>Many thanks for the advice!
>
>Werner
>
>----- Original Message -----
>From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
>To: <aeroelectric-list@matronics.com>
>Subject: Re: AeroElectric-List: Moving Battery and howto
>
>
> > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
><nuckollsr@cox.net>
> >
> > At 06:59 PM 6/8/2005 +0200, you wrote:
> >
> > >--> AeroElectric-List message posted by: "Werner Schneider"
><glastar@gmx.net>
> > >
> > >Dear all,
> > >
> > >I woudl like to ask for your advice, my plane (a Glastar) is quite nose
> > >heavy with the current setup the Battery is directly behind the copilot
> > >seat. Now I would like to move it another 8-10 ft to get a better setup,
>the
> > >question is, can I just get some additional cable and some kind of butt
> > >splices to extend it further after? If yes, where can I get such splices
>for
> > >AWG 2 cables?
> >
> > You betcha . . . but they are bound to be crimp type
> > splices and will need the proper tool for installation.
> > You already have ring terminals crimped or soldered to
> > the battery end of the cables . . . crimp or solder terminals
> > to your extension cables and BOLT them together as a splice.
> > If you can find some double-walled, super-heat shrink to
> > encapsulate the joints, fine. Otherwise, two or three layers
> > of plain-vanilla heat shrink will do.
> >
> > Bob . . .
> >
> >
>
>
Message 5
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| Subject: | Re: Moving Battery and howto |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 07:24 AM 6/9/2005 +0200, you wrote:
>--> AeroElectric-List message posted by: "Werner Schneider" <glastar@gmx.net>
>
>Should have thought about bolting before; as I reduce the cross section here
>I might expect some warming up of the connection during starting I guess,
>but I will follow this easiest route and butt splice just the battery-bus
>items.
>
>Many thanks for the advice!
Your concerns about heating at a reduced cross-section
are not well founded. If such a reduction exists over a
small length, it's still well heat-sinked by wire on
either side of the joint. If you were to thermocouple
the joint and conduct a "hard start" . . . you'd be
hard pressed to measure more than a few degrees rise
in temperature at the joint.
Bob . . .
Message 6
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| Subject: | Re: Capacitance style fuel level sensor |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 11:20 PM 6/8/2005 -0400, you wrote:
>--> AeroElectric-List message posted by: "Richard E. Tasker"
><retasker@optonline.net>
>
>This is a great part but is intended for use with silicon capacitance
>sensors (e.g. silicon capacitance pressure sensor) and as such works
>with very low capacitances. The capacitance fuel level sensors are
>typically 1-2 orders of magnitude greater than what this chip will work
>with (80-150pf empty to full for the fuel sensor vs 4 pf for the AD7745).
>
>We may be using this for our new low (ultra low) pressure sensor, but it
>is not suitable for the typical fuel sensors.
Dick, thanks for reviewing this data and posting your findings.
Bob . . .
Message 7
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| Subject: | Re: Intercom Wiring |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 07:06 PM 6/8/2005 -0700, you wrote:
>--> AeroElectric-List message posted by: Guy Buchanan <bnn@nethere.com>
>
>At 06:48 AM 6/8/2005, you wrote:
> >--> AeroElectric-List message posted by: rv-9a-online
> <rv-9a-online@telus.net>
> >
> >Guy, the Sigtronics instructions are not particularly clear.
> >
> >Using two-wire shielded cable, with the shields grounded to a single
> >point ('A') at the intercom end, wire in these three signals. In each
> >cable, use one wire for signal (both ends), one wire for signal ground
> >(both ends) and the shield (intercom end only).
>
>Hmmmm. This leads me to think I might have wired the headphone and mic
>jacks incorrectly. I used two conductor shielded for the headphones, with
>ring and tip in the conductors, and shield from barrel to 'A'. Should I
>have used three conductor shielded and not grounded the shield at both
>ends? Is that the same for the mic? Should I have used two conductor
>shielded for the mic, instead of one conductor shielded?
Shielding is of minimal if not zero value in wiring of mic and
headset leads. There are few noise sources in your panel wiring
that will propagate noise from one wire to the next via electrostatic
coupling. I very often use shielded wire and take advantage of the
shield as a signal return line in mic, headset and other small
signal applications . . . mostly as a convenience and almost never
as a noise abatement technique.
A twisted trio for microphones and twisted pair for headsets
is entirely adequate for installing these accessories. The insulating
washers called out in other posts will mitigate 99.9% of noise
problems associated with installation practices for microphone
and headset wiring.
Bob . . .
Message 8
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| Subject: | Re: Capacitance style fuel level sensor |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 09:33 PM 6/8/2005 -0400, you wrote:
>--> AeroElectric-List message posted by: Charlie Kuss <chaztuna@adelphia.net>
>
>Eric
> Do I understand this correctly? It appears that your recommendation is a
>"single chip" solution to this problem. Might you consider producing these
>and selling them?? I need two of them for my "Vans" capacitance senders.
>Charlie Kuss
This wouldn't be a single chip solution . . . the device cited is an
accessory
to a microprocessor based where capacitance values are extrapolated and
converted to a serial data stream. At a minimum, using the 7745 in
a measurement system requires a uProcessor and some means for outputing
data in a form suited for panel display. This indicates a software task
as well.
Bob . . .
Message 9
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| Subject: | Re: Battery Testing |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 05:50 PM 6/8/2005 -0700, you wrote:
>--> AeroElectric-List message posted by: "DonVS" <dsvs@comcast.net>
>
>Bob,
>Now that you have found and recommend a cap tester and a separate load
>tester, how about a short article on what to test, how often to test and any
>other pertinent info you feel would be of help. This way we would all be on
>the same page with this equipment. Thanks. Don
I've considered this. There's an aged article at . . .
http://aeroelectric.com/articles/battest.pdf
that was basically excerpted from the 'Connection
that could be updated to speak to these low-cost
battery maintenance tools.
I'll put it up on the stove for future consideration.
Even with this updated article, I'm still of the
opinion that spending $time$ to acquire and use
tools for battery testing may be poor return on
investment . . . the cost of a new, el-cheeso
battery installed at every annual is pretty attractive.
Consider the load-tester/cap-tester combo at $160.
Consider the $time$ of approximately 1 hour to conduct
all the tests even if the battery is not removed from
the airplane (you also have to consider the $time$
value of a computer to support the CBA-II).
Let's assume you can get three years service out
of a $high$ battery by periodic testing. Assume
the "good" battery is $100 and the el-chesso is
$50. By the time you've tested your premium battery
say three times with $160+ worth of equipment, was
the "savings" of $50 worth it?
I think the article needs to be updated but I'm
certainly not going to offer its content as
a recommended procedure for economical ownership
of an airplane . . . I think I'll bring this out
in the article as well.
I've purchased all that stuff and used it to
educate myself in the mysteries of battery
physics and application. However, if I owned
an airplane, I'm not sure I'd find it economically
practical to periodically test the ship's battery
even though I have the equipment which has already
been depreciated to $0$ for other considerations.
Now, if you owned a CERTIFIED ship and the battery
was several hundreds to thousands of dollars (not
unusual for a bizjet), then periodic cap checks
are not only good ownership, they help you comply
with regulations. However, I just don't perceive
favorable economics in doing this on an OBAM S.E.
aircraft.
Bob . . .
Message 10
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| Subject: | Re: Thermocouples in an ultralight - theory help, |
please?
--> AeroElectric-List message posted by: AI Nut <ainut@hiwaay.net>
No.
Richard Riley wrote:
>--> AeroElectric-List message posted by: Richard Riley <richard@riley.net>
>
>I'm installing a 22 hp single cyl 2 stroke in an open frame ultralight.
>
>I'm using a CHT/EGT combo analog gauge. Can I transition from the
>thermocouple wire to copper at the end of the probe wire? Since everything
>is out in the open air, and thus should all be at about the same temperature?
>
>
>.
>
>
>
Message 11
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| Subject: | Re: Thermocouples in an ultralight - theory help, |
please?
--> AeroElectric-List message posted by: AI Nut <ainut@hiwaay.net>
Copper, indeed any metal that is not what that particular TC was
calibrated with, will most likely incude large errors in the final readings.
Robert L. Nuckolls, III help wrote:
>--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
help, please?
>
>At 10:52 PM 6/8/2005 -0700, you wrote:
>
>
>
>>--> AeroElectric-List message posted by: Richard Riley <richard@riley.net>
>>
>>I'm installing a 22 hp single cyl 2 stroke in an open frame ultralight.
>>
>>I'm using a CHT/EGT combo analog gauge. Can I transition from the
>>thermocouple wire to copper at the end of the probe wire? Since everything
>>is out in the open air, and thus should all be at about the same
>>temperature?
>>
>>
>
>
> If you have a stand-alone gage (like View -C- in Figure 14-10
> of 'Connection or in:
>
>http://aeroelectric.com/articles/excerpt.pdf
>
> then the instrument is calibrated assuming that the cold
> junction occurs inside or at the rear of the instrument.
> In an airplane like an ultralight, your supposition that
> ambient temperatures at a remote cold junction and at
> the instrument will be fairly close is a good one . . .
> as long as the remote junction is not exposed to localized
> heating from the engine.
>
> The always-proper way to extend thermocouples in any
> instrumentation package is with thermocouple wire which
> is readily available as cited in another post. In this
> case, however, you're not likely to introduce serious
> errors by using copper to extend the wires.
>
> Bob . . .
>
>
>.
>
>
>
Message 12
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| Subject: | Re: Intercom Wiring |
--> AeroElectric-List message posted by: rv-9a-online <rv-9a-online@telus.net>
Bob points out the use of twisted pair wiring for headsets and mics.
A well-constructed balanced twisted pair is extremely noise immune.
This technique is used in telephone systems and data networking (fast
ethernet, gigabit ethernet).
The reason for the noise immunity is that both wires are subject to
almost exactly the same interference due to the twist characteristics
(i.e. both wires, on average, are the same distance from an interfering
source).
In fact, shielded twisted pair wire has fallen out of practice in modern
data networking because it offers little additional benefit and is
difficult to install. It's main benefit is to minimize radiation from
the wire pair at high frequencies.
[Geek Speak On]
Now... the twisted pair technique works best if the wires are driven and
terminated in a balanced fashion (i.e. signal+, signal-) with identical
drive and termination impedances (resistances) on both wires. Most
avionics signals are single-ended (i.e. signal, ground) with unbalanced
impedances. This imbalance can lead to higher noise than a true
balanced system.
[Geek Speak Off]
Does this make any difference for us?... probably not. I run headset
wiring from the panel, through a connector and down the fuselage to
beside the seats. Along the way, it parallels interfering sources like
antennas, RS-232 cables and so on. In this application, I would
recommend at least shielded wiring, and preferably a shielded pair
(signal, signal ground). This is the belt and suspenders approach that
is not going to be a problem.
The shoulder washers will give you most of the benefit, shielding more,
and shielded pairs the most.
This information is educational, not necessary a recommendation for what
you should do in your own aircraft. I would not recommend ripping out
perfectly good wiring trying to make it 'perfect'.
As a final comment, the audio system is the most difficult wiring task
(with maybe the exception of the engine monitor) that you will have.
All of those signal sources, shields and connectors challenge your
dexterity. Once you've done the audio, you can wire anything!
Vern Little RV-9A
Message 13
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| Subject: | 12 volt bus in a 24 volt system |
--> AeroElectric-List message posted by: Drdavevk30@aol.com
Bob:
I have a need for a 12 volt bus in my 24 volt electrical system using Z-14
architecture. The 12 volt bus will be used for ground engine cooling fans
(aircraft is a Cirrus VK-30 mid engine pusher) and for some access door solenoids.
The total load should not exceed 25 amps. Can you show me where you would
put that in the Z-14 drawing and also where I might get appropriate DC/DC
convertor?
Dave
drdavevk30@cs.com
Message 14
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| Subject: | Re: Intercom Wiring |
--> AeroElectric-List message posted by: Guy Buchanan <bnn@nethere.com>
At 07:11 AM 6/9/2005, Robert L. Nuckolls, III wrote:
>--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
><nuckollsr@cox.net>
...
> A twisted trio for microphones and twisted pair for headsets
> is entirely adequate for installing these accessories. The insulating
> washers called out in other posts will mitigate 99.9% of noise
> problems associated with installation practices for microphone
> and headset wiring.
>
> Bob . . .
Thanks Bob. I think I was confused by the use of shields as a return on
mags, but then I realized that when the engine's running and the mags are
not grounded, the mag shields are actually "single ended" and will
therefore act as noise shields, unlike those used as signal returns in the
headsets and mics, etc. I don't think I'll do the repair now, but will go
forward with Vern's recommendations on the rest of the intercom. I realized
I'd only have to pull two new mic wires, as I can shift the stereo headset
wiring to the mics and get true shielding. Not so bad in a Kitfox, but I'll
wait and see what happens. I want to get this thing FLYING!
Thanks again,
Guy Buchanan
K-IV 1200 / 582 / 99% done, thanks to Bob Ducar.
Do not archive
Message 15
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| Subject: | Re: Intercom Wiring |
--> AeroElectric-List message posted by: Guy Buchanan <bnn@nethere.com>
At 10:48 PM 6/8/2005, rv-9a-online wrote:
>--> AeroElectric-List message posted by: rv-9a-online <rv-9a-online@telus.net>
...
>I would make sure that your headphone jack is isolated from the airframe
>with shoulder washers, available at B&C. This will prevent ground loops.
Good. That's been done.
>Similarly, you may get away with wiring the mic this way. Again, make
>sure that you are using shoulder washers.
...
>Just use the shoulder washers, declare victory and go flying.
I'll try it and see if it works. I can always fix it later. (Though I hate
de-bugging.)
Thanks again Vern.
Guy Buchanan
K-IV 1200 / 582 / 99% done, thanks to Bob Ducar.
Do not archive
Message 16
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--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Comments/Questions:
(1) What's the differences between a current limiter an ammeter shunt??
While they have similarities in appearance, current limiters
and shunts are entirely different critters. Shunts are a precision
high current resistor that converts large current values into tiny
buy calibrated voltages for display on a remote ammeter display.
A current limiter is a large fuse.
2. There is no way to make my conncetion for the battery contactor
to the battery bus 6" it will be 8 to 10' . Can I up size the wire?
The purpose of a battery contactor is to ISOLATE the vast
majority of ship's wiring from the battery for crash
safety. Please find a way to mount the battery contactor
as close as practical to the battery.
Bob . . .
Message 17
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| Subject: | Difficulties with AC motor |
Z-USANET-MsgId: XID554JFiRCq0329X31
1.25 RCVD_NUMERIC_HELO Received: contains an IP address used for HELO
--> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
I'm hoping someone out there can clear something up for me.
We're putting an electrically-powered AC into the Lancair we're building.
Before we turn on the engine we'd like to be able to run this from 110V ground
power - rather than simply a GPU cart. Unfortunately, that'll require about
25-30 amps of 110VAC power to run at full blast (it's 100 Amps max at 28VDC,
80 for the compressor, 20 for the fans).
So I thought that it'd be nice to run the AC at a reduced power setting that
only requires a few amps of wall power. Sure, it won't be able to run the AC
at full blast, but even if it cools a bit we're ahead of the game.
In the last 30 minutes I've been told by two different people that trying to
run a 28V compressor at 12 or 14VDC will draw more current than it would pull
at 28. I realize I'm a mechanical engineer, not electrical, but this just
makes no sense to me whatsoever. Sure, to get equal power out of a motor at
half the voltage you've gotta run the current higher. But I'm not looking to
get the same power output at a lower voltage. I've already got a motor wound
that will draw 80 amps at 28V. How much current will _that_ motor draw when
fed with 12?
Beyond the current draw issue, is there any other reason I shouldn't be
attempting this? Is running the compressor at a lower power setting going to
hurt something somehow?
I'm hoping I'm not off my rocker here and I appreciate the input from
everyone. And if I'm _am_ off my rocker I'd much rather know that too!
Thanks-
Chad
Chad Sipperley
Lancair IVP-turbine (under construction)
Phoenix, AZ
Message 18
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| Subject: | Re: 12 volt bus in a 24 volt system |
--> AeroElectric-List message posted by: "Joel Jacobs" <jj@sdf.lonestar.org>
Sorry, not Bob here but might have a solution. Did you say fans? As in -
two? Why not just hook them in series to the 24V bus?
Joel
----- Original Message -----
From: <Drdavevk30@aol.com>
Subject: AeroElectric-List: 12 volt bus in a 24 volt system
> --> AeroElectric-List message posted by: Drdavevk30@aol.com
>
> Bob:
>
> I have a need for a 12 volt bus in my 24 volt electrical system using Z-14
> architecture. The 12 volt bus will be used for ground engine cooling fans
> (aircraft is a Cirrus VK-30 mid engine pusher) and for some access door
solenoids.
> The total load should not exceed 25 amps. Can you show me where you would
> put that in the Z-14 drawing and also where I might get appropriate DC/DC
> convertor?
>
> Dave
> drdavevk30@cs.com
>
>
Message 19
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| Subject: | Difficulties with AC motor |
--> AeroElectric-List message posted by: "Hinde, Frank George (Corvallis)" <frank.hinde@hp.com>
To a fellow mechanical Engineer kudos for knowing when something doesn't
smeel right...:)
The simple resistance is the same so the current will drop to half the
original value..This means available power will drop to 1/4 when running
on 14V vs 28V...Of course this is simple resistance. As we know
intuitively current must go up as we try to slow down a motor this may
or may not hold true if you actually get it running
My best guess is the compressor is unlikly to start with 1/4 of the
available power.
Frank
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
chad-c_sip@stanfordalumni.org
Subject: AeroElectric-List: Difficulties with AC motor
--> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
I'm hoping someone out there can clear something up for me.
We're putting an electrically-powered AC into the Lancair we're
building.
Before we turn on the engine we'd like to be able to run this from 110V
ground power - rather than simply a GPU cart. Unfortunately, that'll
require about 25-30 amps of 110VAC power to run at full blast (it's 100
Amps max at 28VDC, 80 for the compressor, 20 for the fans).
So I thought that it'd be nice to run the AC at a reduced power setting
that only requires a few amps of wall power. Sure, it won't be able to
run the AC at full blast, but even if it cools a bit we're ahead of the
game.
In the last 30 minutes I've been told by two different people that
trying to run a 28V compressor at 12 or 14VDC will draw more current
than it would pull at 28. I realize I'm a mechanical engineer, not
electrical, but this just makes no sense to me whatsoever. Sure, to get
equal power out of a motor at half the voltage you've gotta run the
current higher. But I'm not looking to get the same power output at a
lower voltage. I've already got a motor wound that will draw 80 amps at
28V. How much current will _that_ motor draw when fed with 12?
Beyond the current draw issue, is there any other reason I shouldn't be
attempting this? Is running the compressor at a lower power setting
going to hurt something somehow?
I'm hoping I'm not off my rocker here and I appreciate the input from
everyone. And if I'm _am_ off my rocker I'd much rather know that too!
Thanks-
Chad
Chad Sipperley
Lancair IVP-turbine (under construction) Phoenix, AZ
Message 20
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| Subject: | Re: Difficulties with AC motor |
--> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
How big is this Lancair?? Googling around, I seem to be finding numbers
like 15A at 110VAC for an AC unit large enough to keep a motor home cool..
It seems like the 100A max at 28VDC may be from the inrush current...
Your continuous amperage demand numbers are probably much less.
Can you provide any more information about the AC unit you are planning to
use? The ability to develop a low power mode depends to some extent on
what kind of motor it uses.
If you aren't able to run the unit set on 'kill' (instead of 'stun'),
maybe you need a smaller, less power hungry unit...
Regards,
Matt-
VE N34RD, C150 N714BK
> --> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
>
> I'm hoping someone out there can clear something up for me.
>
> We're putting an electrically-powered AC into the Lancair we're
> building. Before we turn on the engine we'd like to be able to run this
> from 110V ground power - rather than simply a GPU cart. Unfortunately,
> that'll require about 25-30 amps of 110VAC power to run at full blast
> (it's 100 Amps max at 28VDC, 80 for the compressor, 20 for the fans).
>
> So I thought that it'd be nice to run the AC at a reduced power setting
> that only requires a few amps of wall power. Sure, it won't be able to
> run the AC at full blast, but even if it cools a bit we're ahead of the
> game.
>
> In the last 30 minutes I've been told by two different people that
> trying to run a 28V compressor at 12 or 14VDC will draw more current
> than it would pull at 28. I realize I'm a mechanical engineer, not
> electrical, but this just makes no sense to me whatsoever. Sure, to get
> equal power out of a motor at half the voltage you've gotta run the
> current higher. But I'm not looking to get the same power output at a
> lower voltage. I've already got a motor wound that will draw 80 amps at
> 28V. How much current will _that_ motor draw when fed with 12?
>
> Beyond the current draw issue, is there any other reason I shouldn't be
> attempting this? Is running the compressor at a lower power setting
> going to hurt something somehow?
>
> I'm hoping I'm not off my rocker here and I appreciate the input from
> everyone. And if I'm _am_ off my rocker I'd much rather know that too!
>
> Thanks-
>
> Chad
>
>
> Chad Sipperley
> Lancair IVP-turbine (under construction)
> Phoenix, AZ
>
>
Message 21
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| Subject: | Re: Difficulties with AC motor |
Z-USANET-MsgId: XID020JFiuuk0325X30
--> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
First off, I meant to put the subject line as "DC motors" not AC - alas.
Unfortunately I'm in Florida right this minute and the plane is in Arizona so
I can't be more specific. The 80 amps is the peak inrush, yes. The continuous
current is apparently 60 amps so I'm told (by the same folks who were telling
me the current draw would double if i cut the voltage in half). The compressor
unit isn't really all that heavy so we're going to keep the system we've got.
Having too much air conditioning in Phoenix isn't usually something you gripe
about. It'd just be real nice to be able to have the local FBO be able to plug
in the plane an hour before my father plans to head home and have it already
cooled off.
Thanks again for the input.
Chad
Chad Sipperley
Lancair IVP-turbine (under construction)
Phoenix, AZ
------ Original Message ------
From: "Matt Prather" <mprather@spro.net>
Subject: Re: AeroElectric-List: Difficulties with AC motor
> --> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
>
> How big is this Lancair?? Googling around, I seem to be finding numbers
> like 15A at 110VAC for an AC unit large enough to keep a motor home cool..
> It seems like the 100A max at 28VDC may be from the inrush current...
> Your continuous amperage demand numbers are probably much less.
>
> Can you provide any more information about the AC unit you are planning to
> use? The ability to develop a low power mode depends to some extent on
> what kind of motor it uses.
>
> If you aren't able to run the unit set on 'kill' (instead of 'stun'),
> maybe you need a smaller, less power hungry unit...
>
>
> Regards,
>
> Matt-
> VE N34RD, C150 N714BK
>
>
> > --> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
> >
> > I'm hoping someone out there can clear something up for me.
> >
> > We're putting an electrically-powered AC into the Lancair we're
> > building. Before we turn on the engine we'd like to be able to run this
> > from 110V ground power - rather than simply a GPU cart. Unfortunately,
> > that'll require about 25-30 amps of 110VAC power to run at full blast
> > (it's 100 Amps max at 28VDC, 80 for the compressor, 20 for the fans).
> >
> > So I thought that it'd be nice to run the AC at a reduced power setting
> > that only requires a few amps of wall power. Sure, it won't be able to
> > run the AC at full blast, but even if it cools a bit we're ahead of the
> > game.
> >
> > In the last 30 minutes I've been told by two different people that
> > trying to run a 28V compressor at 12 or 14VDC will draw more current
> > than it would pull at 28. I realize I'm a mechanical engineer, not
> > electrical, but this just makes no sense to me whatsoever. Sure, to get
> > equal power out of a motor at half the voltage you've gotta run the
> > current higher. But I'm not looking to get the same power output at a
> > lower voltage. I've already got a motor wound that will draw 80 amps at
> > 28V. How much current will _that_ motor draw when fed with 12?
> >
> > Beyond the current draw issue, is there any other reason I shouldn't be
> > attempting this? Is running the compressor at a lower power setting
> > going to hurt something somehow?
> >
> > I'm hoping I'm not off my rocker here and I appreciate the input from
> > everyone. And if I'm _am_ off my rocker I'd much rather know that too!
> >
> > Thanks-
> >
> > Chad
> >
> >
> > Chad Sipperley
> > Lancair IVP-turbine (under construction)
> > Phoenix, AZ
> >
> >
>
>
>
>
>
>
>
Message 22
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| Subject: | Difficulties with AC motor |
--> AeroElectric-List message posted by: "John Danielson" <johnd@wlcwyo.com>
It looks like it will draw 40amp with 14 volts.
John L. Danielson
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Hinde, Frank George (Corvallis)
Subject: RE: AeroElectric-List: Difficulties with AC motor
--> AeroElectric-List message posted by: "Hinde, Frank George
(Corvallis)" <frank.hinde@hp.com>
To a fellow mechanical Engineer kudos for knowing when something doesn't
smeel right...:)
The simple resistance is the same so the current will drop to half the
original value..This means available power will drop to 1/4 when running
on 14V vs 28V...Of course this is simple resistance. As we know
intuitively current must go up as we try to slow down a motor this may
or may not hold true if you actually get it running
My best guess is the compressor is unlikly to start with 1/4 of the
available power.
Frank
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
chad-c_sip@stanfordalumni.org
Subject: AeroElectric-List: Difficulties with AC motor
--> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
I'm hoping someone out there can clear something up for me.
We're putting an electrically-powered AC into the Lancair we're
building.
Before we turn on the engine we'd like to be able to run this from 110V
ground power - rather than simply a GPU cart. Unfortunately, that'll
require about 25-30 amps of 110VAC power to run at full blast (it's 100
Amps max at 28VDC, 80 for the compressor, 20 for the fans).
So I thought that it'd be nice to run the AC at a reduced power setting
that only requires a few amps of wall power. Sure, it won't be able to
run the AC at full blast, but even if it cools a bit we're ahead of the
game.
In the last 30 minutes I've been told by two different people that
trying to run a 28V compressor at 12 or 14VDC will draw more current
than it would pull at 28. I realize I'm a mechanical engineer, not
electrical, but this just makes no sense to me whatsoever. Sure, to get
equal power out of a motor at half the voltage you've gotta run the
current higher. But I'm not looking to get the same power output at a
lower voltage. I've already got a motor wound that will draw 80 amps at
28V. How much current will _that_ motor draw when fed with 12?
Beyond the current draw issue, is there any other reason I shouldn't be
attempting this? Is running the compressor at a lower power setting
going to hurt something somehow?
I'm hoping I'm not off my rocker here and I appreciate the input from
everyone. And if I'm _am_ off my rocker I'd much rather know that too!
Thanks-
Chad
Chad Sipperley
Lancair IVP-turbine (under construction) Phoenix, AZ
Message 23
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| Subject: | Re: Difficulties with AC motor |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 01:20 PM 6/9/2005 -0700, you wrote:
>--> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
>
>First off, I meant to put the subject line as "DC motors" not AC - alas.
>
>Unfortunately I'm in Florida right this minute and the plane is in Arizona so
>I can't be more specific. The 80 amps is the peak inrush, yes. The continuous
>current is apparently 60 amps so I'm told (by the same folks who were telling
>me the current draw would double if i cut the voltage in half). The compressor
>unit isn't really all that heavy so we're going to keep the system we've got.
>Having too much air conditioning in Phoenix isn't usually something you gripe
>about. It'd just be real nice to be able to have the local FBO be able to plug
>in the plane an hour before my father plans to head home and have it already
>cooled off.
>
>Thanks again for the input.
>
>Chad
The off-hand estimate of current increase with decreased
voltage assumes that horsepower to produce designed flow
of Freon in the A/C will be a constant irrespective of
motor RPM . . . motor RPM will fall to 1/2 or less depending
on design of the motor. Unless there's a VERY agile expansion
valve capable of maintaining design pressure on the system at
low flow, both flow and pressure will go down as well which
means that horsepower the system can absorb will probably
be way less than 1/2 of design value.
I think the level of cooling to be expected at 1/2 voltage
will be very disappointing. A 28 volt ground power carts
is very much in order. How would you get 14v? Doesn't
the FBO have a 28v ground power cart? If this is the
ship's home base, consider building a dedicated ground
power cart. You can get 28v from a 14v alternator with
use of proper regulator and spinning it fast enough.
80A continuous at 28v is 3 electrical horspower. A 5 hp
engine driving a 14v, 100A alternator combined with a
couple of 12v RG batteries could be assembled into
a reasonably compact, dedicated GPU for running your
A/C at full bore.
Bob . . .
Message 24
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| Subject: | Re: 12 volt bus in a 24 volt system |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 01:37 PM 6/9/2005 -0400, you wrote:
>--> AeroElectric-List message posted by: "Joel Jacobs" <jj@sdf.lonestar.org>
>
>Sorry, not Bob here but might have a solution. Did you say fans? As in -
>two? Why not just hook them in series to the 24V bus?
>Joel
I had a Cirrus builder do just that about 10 years ago.
I think it worked okay . . . never heard from him again
after we talked the first time about this solution.
Bob . . .
Message 25
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|
| Subject: | Difficulties with AC motor |
--> AeroElectric-List message posted by: "Hinde, Frank George (Corvallis)" <frank.hinde@hp.com>
But MUCH more important than any of this is...How on Earth does a
mechanical engineer afford to build a lancair ivP?...I mean there I am
telling my bosses about how undervalued we are and there is one in our
midst with a $300,000 homebuilt airplane...Really makes it a tough sell
y'know...:)
Frank
Do not archive
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Robert L. Nuckolls, III
Subject: Re: AeroElectric-List: Difficulties with AC motor
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
--> <nuckollsr@cox.net>
At 01:20 PM 6/9/2005 -0700, you wrote:
>--> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
>
>First off, I meant to put the subject line as "DC motors" not AC -
alas.
>
>Unfortunately I'm in Florida right this minute and the plane is in
>Arizona so I can't be more specific. The 80 amps is the peak inrush,
>yes. The continuous current is apparently 60 amps so I'm told (by the
>same folks who were telling me the current draw would double if i cut
>the voltage in half). The compressor unit isn't really all that heavy
so we're going to keep the system we've got.
>Having too much air conditioning in Phoenix isn't usually something you
>gripe about. It'd just be real nice to be able to have the local FBO be
>able to plug in the plane an hour before my father plans to head home
>and have it already cooled off.
>
>Thanks again for the input.
>
>Chad
The off-hand estimate of current increase with decreased
voltage assumes that horsepower to produce designed flow
of Freon in the A/C will be a constant irrespective of
motor RPM . . . motor RPM will fall to 1/2 or less depending
on design of the motor. Unless there's a VERY agile expansion
valve capable of maintaining design pressure on the system at
low flow, both flow and pressure will go down as well which
means that horsepower the system can absorb will probably
be way less than 1/2 of design value.
I think the level of cooling to be expected at 1/2 voltage
will be very disappointing. A 28 volt ground power carts
is very much in order. How would you get 14v? Doesn't
the FBO have a 28v ground power cart? If this is the
ship's home base, consider building a dedicated ground
power cart. You can get 28v from a 14v alternator with
use of proper regulator and spinning it fast enough.
80A continuous at 28v is 3 electrical horspower. A 5 hp
engine driving a 14v, 100A alternator combined with a
couple of 12v RG batteries could be assembled into
a reasonably compact, dedicated GPU for running your
A/C at full bore.
Bob . . .
Message 26
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| Subject: | Difficulties with AC motor |
Z-USANET-MsgId: XID700JFJaBd0268X28
--> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
too funny - be asasured that my father (the surgeon) is the one who's building
the plane. I'm just helping *grin*.
Chad
do not archive
------ Original Message ------
From: "Hinde, Frank George (Corvallis)" <frank.hinde@hp.com>
Subject: RE: AeroElectric-List: Difficulties with AC motor
> --> AeroElectric-List message posted by: "Hinde, Frank George (Corvallis)"
<frank.hinde@hp.com>
>
> But MUCH more important than any of this is...How on Earth does a
> mechanical engineer afford to build a lancair ivP?...I mean there I am
> telling my bosses about how undervalued we are and there is one in our
> midst with a $300,000 homebuilt airplane...Really makes it a tough sell
> y'know...:)
>
> Frank
>
> Do not archive
>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
> Robert L. Nuckolls, III
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: Difficulties with AC motor
>
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> --> <nuckollsr@cox.net>
>
> At 01:20 PM 6/9/2005 -0700, you wrote:
>
> >--> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
> >
> >First off, I meant to put the subject line as "DC motors" not AC -
> alas.
> >
> >Unfortunately I'm in Florida right this minute and the plane is in
> >Arizona so I can't be more specific. The 80 amps is the peak inrush,
> >yes. The continuous current is apparently 60 amps so I'm told (by the
> >same folks who were telling me the current draw would double if i cut
> >the voltage in half). The compressor unit isn't really all that heavy
> so we're going to keep the system we've got.
> >Having too much air conditioning in Phoenix isn't usually something you
>
> >gripe about. It'd just be real nice to be able to have the local FBO be
>
> >able to plug in the plane an hour before my father plans to head home
> >and have it already cooled off.
> >
> >Thanks again for the input.
> >
> >Chad
>
> The off-hand estimate of current increase with decreased
> voltage assumes that horsepower to produce designed flow
> of Freon in the A/C will be a constant irrespective of
> motor RPM . . . motor RPM will fall to 1/2 or less depending
> on design of the motor. Unless there's a VERY agile expansion
> valve capable of maintaining design pressure on the system at
> low flow, both flow and pressure will go down as well which
> means that horsepower the system can absorb will probably
> be way less than 1/2 of design value.
>
> I think the level of cooling to be expected at 1/2 voltage
> will be very disappointing. A 28 volt ground power carts
> is very much in order. How would you get 14v? Doesn't
> the FBO have a 28v ground power cart? If this is the
> ship's home base, consider building a dedicated ground
> power cart. You can get 28v from a 14v alternator with
> use of proper regulator and spinning it fast enough.
> 80A continuous at 28v is 3 electrical horspower. A 5 hp
> engine driving a 14v, 100A alternator combined with a
> couple of 12v RG batteries could be assembled into
> a reasonably compact, dedicated GPU for running your
> A/C at full bore.
>
> Bob . . .
>
>
>
>
>
>
>
Message 27
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| Subject: | Re: Difficulties with AC motor |
Z-USANET-MsgId: XID969JFJaip0256X38
--> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
In our own hangar we'll have no problem setting up our own ground cart to run
the A/C at full power. The desire was to have the ability to run a 110
extension cord to any old outlet anywhere to cool the plane down a bit before
climbing in. Even if the A/C can only remove 1/4 the BTUs of heat as at full
power I'll take it. Instead of having the compressor come on only part time,
it'll just run 100% duty cycle.
I'm not sure that the FBOs on foreign fields will let us borrow a GPU for 20
minutes every time we want to fly home. And certainly, if the effective
cooling we get is near nil then we'll pull the AC-DC converter and give up on
the idea of running the A/C off 110 power. But until then I'd like to give it
a shot and see if it can actually cool the airplane down. After all, it's an
experimental airplane. This sounds like an experiment worth at least trying.
Chad
Chad Sipperley
Lancair IVP-turbine (under construction)
Phoenix, AZ
------ Original Message ------
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Subject: Re: AeroElectric-List: Difficulties with AC motor
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<nuckollsr@cox.net>
>
> At 01:20 PM 6/9/2005 -0700, you wrote:
>
> >--> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
> >
> >First off, I meant to put the subject line as "DC motors" not AC - alas.
> >
> >Unfortunately I'm in Florida right this minute and the plane is in Arizona
so
> >I can't be more specific. The 80 amps is the peak inrush, yes. The
continuous
> >current is apparently 60 amps so I'm told (by the same folks who were
telling
> >me the current draw would double if i cut the voltage in half). The
compressor
> >unit isn't really all that heavy so we're going to keep the system we've
got.
> >Having too much air conditioning in Phoenix isn't usually something you
gripe
> >about. It'd just be real nice to be able to have the local FBO be able to
plug
> >in the plane an hour before my father plans to head home and have it
already
> >cooled off.
> >
> >Thanks again for the input.
> >
> >Chad
>
> The off-hand estimate of current increase with decreased
> voltage assumes that horsepower to produce designed flow
> of Freon in the A/C will be a constant irrespective of
> motor RPM . . . motor RPM will fall to 1/2 or less depending
> on design of the motor. Unless there's a VERY agile expansion
> valve capable of maintaining design pressure on the system at
> low flow, both flow and pressure will go down as well which
> means that horsepower the system can absorb will probably
> be way less than 1/2 of design value.
>
> I think the level of cooling to be expected at 1/2 voltage
> will be very disappointing. A 28 volt ground power carts
> is very much in order. How would you get 14v? Doesn't
> the FBO have a 28v ground power cart? If this is the
> ship's home base, consider building a dedicated ground
> power cart. You can get 28v from a 14v alternator with
> use of proper regulator and spinning it fast enough.
> 80A continuous at 28v is 3 electrical horspower. A 5 hp
> engine driving a 14v, 100A alternator combined with a
> couple of 12v RG batteries could be assembled into
> a reasonably compact, dedicated GPU for running your
> A/C at full bore.
>
> Bob . . .
>
>
>
>
>
>
>
Message 28
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| Subject: | Re: 12 volt bus in a 24 volt system |
Z-USANET-MsgId: XID501JFJaLM0243X36
--> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
Okay, fans are an inductive load and lights are not. But I've wired a couple
of Hella lamps as taxi lamps in series and they seem to be working like a
charm. They draw exactly the same current in series at 28V as they each do
when driven from a 14V source. You might make sure that nothing in the case is
electrically connected to the "ground" lead on the higher-potential fan. If
anything is grounded and you try and float one fan you'll create a nasty
short.
Chad
Chad Sipperley
Lancair IVP-turbine (under construction)
Phoenix, AZ
------ Original Message ------
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Subject: Re: AeroElectric-List: 12 volt bus in a 24 volt system
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<nuckollsr@cox.net>
>
> At 01:37 PM 6/9/2005 -0400, you wrote:
>
> >--> AeroElectric-List message posted by: "Joel Jacobs"
<jj@sdf.lonestar.org>
> >
> >Sorry, not Bob here but might have a solution. Did you say fans? As in -
> >two? Why not just hook them in series to the 24V bus?
> >Joel
>
> I had a Cirrus builder do just that about 10 years ago.
> I think it worked okay . . . never heard from him again
> after we talked the first time about this solution.
>
> Bob . . .
>
>
>
>
>
>
>
Message 29
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SpamAssassin (score=-2.572, required 4, autolearn=not spam, AWL 0.03,
BAYES_00 -2.60)
--> AeroElectric-List message posted by: "Larry E. James" <larry@ncproto.com>
> In the end, I'd be just as confident to fly with the
Z-19 design as much
>>as the Z-13 + Z-30 design. While Z-19 is cheaper, it's a
lot more weight
>>that I won't need in my RV7-A.
>> I'm not totally decided yet being that I won't have
to start installing
>>a chosen system until later this Fall, but Z-13 + Z30
looks good to me. Now
>>if Bob would only add the Z-30 extra battery to the
Z-13/SD-8 drawing and
>>show it as one sheet...
> I'll leave this up to you. The more I specialize the
base drawings,
>the more it begins to look like I am recommending this
architecture
>as "THE way to go" . . .
Vern and Bob,
I'm also in agreement here. I'm working up a load sheet and
basic wiring diagram now. I just built / installed my
battery tray: I made it fit an Odyssey PC625 with enough
room to easily add another PC625 although I doubt I would
ever do that; instead I have open the more likely option of
adding a second battery of smaller size (and weight). Neat
stuff.
Larry E. James
Bellevue, WA HR2
Message 30
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| Subject: | 12 volt bus in a 24 volt system |
--> AeroElectric-List message posted by: Drdavevk30@aol.com
Bob:
Thanks for the suggestions of wiring fans in series. I am concerned that the
metal fan motor, housing, mounting brackets will ground out to the metal
fireproofing and cause problems. The old Cirrus fans were plastic housings and
mountings and the old fireproofing was phenolic/resin unlike my situation. The
other problem has been with the plastic fans partly melting/yielding a bit in
hot conditions.
I also have the access door solenoids (12 volts) to contend with.
Is there anyway to have a separate 12 volt bus in Z-14 as I originally
inquired?
Dave D.
Message 31
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| Subject: | Re: 12 volt bus in a 24 volt system |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
--> AeroElectric-List message posted by: Drdavevk30@aol.com
>Is there anyway to have a separate 12 volt bus in Z-14 as I originally
inquired? Dave D.
Dr. Dave,
Trust us on this. We wouldn't steer you wrong. If you really want a DC-DC
converter then go to
http://www.vicorpower.com/documents/datasheets/ds_compac.pdf There are many
other companies who will sell you what you asked for.
But you really don't want to do this. Get the fans with the right voltages
or wire them in series. The door solenoids can be fixed by adding a resistor
in series.
Trying to maintain a couple MAJOR power supplies with different voltages in
your VK30 is not a good idea. You can do it, but you can also train a dog to
walk on its back legs. Why bother?
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
Phone (508) 764-2072
Email: emjones@charter.net
"The problem with the world is that only the intelligent people want to be
smarter, and only the good people want to improve."
- E. Stobblehouse
Message 32
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| Subject: | Re: Thermocouples in an ultralight - theory help, |
please?
--> AeroElectric-List message posted by: "Richard E. Tasker" <retasker@optonline.net>
please?
Baloney. If, as the original poster suggests, the instrument and the
end of the TC probe are at the same temperature you could connect them
with anything you want to. The reason that one normally uses
thermocouple extension wire to connect a TC probe to the remote mounted
instrument is because they are frequently at different temperatures -
and probably unpredictably different. For that case it is important to
use extension wire.
If the two junctions are at the same temperature, any emf generated is
either canceled out or is only the same as it the copper wire wasn't
there. That is, the terminals that the TC wire normally connects to on
the instrument are probably copper or brass or possibly nickel plated.
The connection between the TC wires generates an EMF that is canceled
out by the cold junction compensation circuitry in the instrument. If
you add a length of wire between the TC and the instrument, and assuming
the two junctions are at the same temperature, you have done nothing but
move the location of the cold junction - the EMFs at the instrument will
be exactly the same as without the additional copper wire.
Furthermore, the errors would not be "large" in any case. In fact, any
error will be exactly the difference in temperature between the
TC/copper wire junction and the copper wire/instrument junction. Unless
either of these junctions are very close to the engine, the practical
difference is minimal.
All the above applies to the original poster's situation. In a "normal"
GA or experimental with a closed cowl and a separate cockpit, the errors
could be significant.
If you want more theory, just ask and I can give it to you. :-)
Dick Tasker
AI Nut wrote:
>--> AeroElectric-List message posted by: AI Nut <ainut@hiwaay.net>
>
>Copper, indeed any metal that is not what that particular TC was
>calibrated with, will most likely incude large errors in the final readings.
>
>
>Robert L. Nuckolls, III help wrote:
>
>
>
>>--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
help, please?
>>
>>At 10:52 PM 6/8/2005 -0700, you wrote:
>>
>>
>>
>>
>>
>>>--> AeroElectric-List message posted by: Richard Riley <richard@riley.net>
>>>
>>>I'm installing a 22 hp single cyl 2 stroke in an open frame ultralight.
>>>
>>>I'm using a CHT/EGT combo analog gauge. Can I transition from the
>>>thermocouple wire to copper at the end of the probe wire? Since everything
>>>is out in the open air, and thus should all be at about the same
>>>temperature?
>>>
>>>
>>>
>>>
>> If you have a stand-alone gage (like View -C- in Figure 14-10
>> of 'Connection or in:
>>
>>http://aeroelectric.com/articles/excerpt.pdf
>>
>> then the instrument is calibrated assuming that the cold
>> junction occurs inside or at the rear of the instrument.
>> In an airplane like an ultralight, your supposition that
>> ambient temperatures at a remote cold junction and at
>> the instrument will be fairly close is a good one . . .
>> as long as the remote junction is not exposed to localized
>> heating from the engine.
>>
>> The always-proper way to extend thermocouples in any
>> instrumentation package is with thermocouple wire which
>> is readily available as cited in another post. In this
>> case, however, you're not likely to introduce serious
>> errors by using copper to extend the wires.
>>
>> Bob . . .
>>
>>
>>.
>>
>>
>>
>>
>>
>
>
>
>
--
----
Please Note:
No trees were destroyed in the sending of this message. We do concede, however,
that a significant number of electrons may have been temporarily inconvenienced.
----
Message 33
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| Subject: | Re: battery maintainer More |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 09:00 AM 6/8/2005 -0600, you wrote:
>--> AeroElectric-List message posted by: Paul Wilson <pwilson@climber.org>
>
>I have an "automatic 1.5 amp Schumacher SE-1-12S" I use all the time for
>various batteries, tractor, un-used truck etc. This unit is stocked a the
>local battery store so is readily available. I think I got mine at Walmart
>years ago. With all the discussion I decided to see how it works. I put it
>on a yellow Optima which is a deep cycle spiral glass matt 750 cca, 55AH.
>Too big for a plane but a good choice for a car/truck. Weighs 46 pounds.
> I just clock watched to see what the volts were.
>initial 12.38 after sitting for 6 months
>1 minute 12.94
>2 minutes 13.45
>1 hour 12.76
>3 hours 12.67
>22 hours 12.68
Hmmmm . . . doesn't like like this critter goes into much
of a maintenance mode . . . endpoint voltage is less than
the float voltage of a fully charged battery. Further,
we don't know if it went into a top-off mode by pulling
the battery up to better than 14 volts.
>Don't know how high it got.
> To lazy to do the same test on my small lawn tractor battery (similar to
>a light plane battery). It is a glass matt with 340 cca, ?AH and after a
>being plugged in for a week I remember the volts were around 12.6.
> The charger sells for $42 to $27 on the net, locally for $28.95.
> Seems like it wont hurt a battery if left plugged in for long periods. It
>comes with a bracket to mount under the hood of a car and had bolted
>eyelets. A portable version with clips is SE1562A sells for an extra $4
>locally.
You're correct, it won't hurt the battery on long term charge,
but it would be interesting to know how well it works
for topping off a dead battery and then storing it. The
numbers you've cited don't offer warm fuzzies about it.
Bob . . .
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