Today's Message Index:
----------------------
1. 05:42 AM - Re: Transorbs and Lightning (Robert L. Nuckolls, III)
2. 05:49 AM - Re: Stacked 14v systems for 28v (Robert L. Nuckolls, III)
3. 06:12 AM - Re: Slick mag P-lead ground wire (Mike Lehman)
4. 06:42 AM - Re: Re: Slick mag P-lead ground wire (Robert L. Nuckolls, III)
5. 06:47 AM - Re: Re: Stacked 14v systems for 28v (Deems Davis)
6. 08:45 AM - Reasonable qualification for flight hardware? ()
7. 09:13 AM - Re: Stacked 14v systems for 28v (Eric M. Jones)
8. 09:21 AM - Re: Reasonable qualification for flight hardware? (Hinde, Frank George (Corvallis))
9. 10:20 AM - Re: Re: Stacked 14v systems for 28v (Deems Davis)
10. 10:55 AM - Re: Re: Slick mag P-lead ground wire (aaa@pacifier.com)
11. 11:21 AM - Re: 'Scope offer from Saelig (Joe Garner)
12. 11:24 AM - Re: Re: Stacked 14v systems for 28v (Richard Tasker)
13. 01:35 PM - Re: Stacked 14v systems for 28v (Eric M. Jones)
14. 03:42 PM - Transistorture (Fiveonepw@aol.com)
Message 1
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| Subject: | Re: Transorbs and Lightning |
At 09:45 AM 11/8/2006 -0600, you wrote:
><rvbuilder@sausen.net>
>
>So that would be a maybe?
Sure . . . but 'maybe' comes in all sizes, flavors and
assurances. When Paul's airplane took the hit it appears
that the stroke came in one wingtip and out the other.
Since the current carrying paths for this event was wiring,
the qualification protocols would fall under "direct effects".
See:
http://www.aeroelectric.com/articles/Anatomy_of_a_Lightning_Strike.pdf
I gotta tell ya, when you take the direct hit, the design goals
have more to do with keeping the damage confined to the one
system . . . there's no Transorb made that will confidently
stand between mother nature's fireworks and your micro-processors,
itty-bitty resistors and light bulbs.
So yeah, I can agree that if Paul's airplane was generously
fitted with Transorbs, he MIGHT have suffered a bit less damage.
But as you can see from his post-event investigation, damage
levels were high enough to leave tracks on structure, burned
wires and caused internal damage sufficient to be manifest outside
the devices enclosure.
I cannot recommend the sprinkling of "Transorb dust" on your
airplane because the notion is not supported by the understanding
of simple-ideas. DO-160 testing and similar efforts are
repeatable experiments that have been demonstrated over
time to have value. There are numbers assigned to stress levels
and techniques designed to stand off those hazards.
If a builder is inclined to embrace "Transorb dust" as a
good thing to do, I'll suggest there is risk that the same
builder is subject to unsupported confidence in his/her
system to knock on the gates of hell and run away unscathed.
Many a good soul has been disappointed that boots and perhaps
a hot-prop didn't take them through "that little bit of ice".
To hypothesize about and recommend techniques that
can only be tested at the edges of the airplane's envelope
with pilot an passengers aboard is not good engineering.
It's far better that we do not venture up to those edges.
Bob . . .
> ><paul.mcallister@qia.net>
> >
> >Bob et al.
> >
> >Some time ago my aircraft took a lightning hit which damaged many
> >electronic devices, with the exception of the Apollo GX60 and SL70.
> >Now I don't know if this was because these are well designed products
> >or they were just having a lucky day, but my question, would a heavy
> >duty transorb help in a catastrophic even like this ?
> >
> >Paul
Message 2
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| Subject: | Re: Stacked 14v systems for 28v |
At 05:52 PM 11/8/2006 -0700, you wrote:
>
>Well based on the response form Bob and others I revisited the Engine/Belt
>driven A/C system. It turns out that with my engine and cowl combination
>that there is not room enough to mount both a compressor and an
>alternator. So, it looks like my options are; either to convert my
>electric system to 28v (ugh!). or pursue the 'stacked' approach.
>
>Bob:
>
>When you say 'electrically isolated' are you saying that the "top" system
>would have to NOT share a common ground with the bottom system? what other
>'isolation' would be required
>
>"This would require a special alternator for the #2 machine." I assume
>you are referring to the "top" system (?) could the SD-20 perform this
>function as the alternator for the #2 machine, what is the "Special"
>requirement of this alternator.
No, the SD-20 is a 20amp machine. I'm suspecting that both
of your 14 volt systems will need to be in the 60 amp class
or larger. How much power does that a/c compressor need?
The "top" system cannot be grounded to airframe. Alernators
have diode arrays that are common to the alternator case by
design. If I were crafting a floating system for stacking,
I'd bypass the built in diodes and bring all of the alternator's
field and stator wires out to be handled as needed for
the system to run 14v above ground.
>A bottom alternator large enough to carry ship's load plus the A/C load is
>not a problem.
>
>
>Re: backing up the bottom with the top. When you say 'complex switching' I
>infer this is more than just the cross feed contactor approach in Z14,
>care to elaborate any further?
The problem is similar to the use of two batteries
in series for starting and running them in parallel
for flying. You need to sequence contactors in the right
order to accomplish the switching . . . stuck contactors
can create potential for spectacular events (a number of
MU-2's were set on fire about 35 years ago before they
installed limiters).
>Thanks for the information and advice so far and for any additional
>insight you can provide.
This is a MAJOR task. You'll have to fabricate a special
alternator regulator installation but is all possible.
Bob . . .
Message 3
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| Subject: | Re: Slick mag P-lead ground wire |
Bob,
I have found a certified aircraft with the P-lead shield grounded at the mag
switch end as well as on the mag housing. Is there a down-side (i.e. noise)
to grounding the shield at both ends? (Surprisingly, the Maintenance Manual
for the aircraft does not include wiring for the mag switch or P-lead.)
Mike
>2) Do I ground the center conductor to a local ground point at the switch
>on the panel or do I ground it to the coax outer conductor?
Grounding to shield is preferred. See exemplar schematics
in:
http://aeroelectric.com/articles/Rev11/AppZ_R11J.pdf
Bob . . .
Message 4
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| Subject: | Re: Slick mag P-lead ground wire |
At 09:12 AM 11/9/2006 -0500, you wrote:
>
>Bob,
>
>I have found a certified aircraft with the P-lead shield grounded at the mag
>switch end as well as on the mag housing. Is there a down-side (i.e. noise)
>to grounding the shield at both ends? (Surprisingly, the Maintenance Manual
>for the aircraft does not include wiring for the mag switch or P-lead.)
There's a number of discussions for p-lead treatment in
http://www.aeroelectric.com/articles/MagnetoSwitchOptions.pdf
and
http://www.aeroelectric.com/FAQ/AeroElectric-List/AeroElectric-List_FAQ.pdf
Open the .pdf files and search on "p-lead".
In a nutshell, for best noise reduction -AND- avoidance of
a fabricated ground loop, it's best to ground the shield at
one end only (mag end) and use the shield as the ground return
for the mag switch as illustrated in the z-figures and cited
in the two links above.
Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
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| Subject: | Re: Stacked 14v systems for 28v |
Thanks again Bob,
The electric A/C system consumes 45 amps at peak load. Do _both_
alternators need to be capable of carrying ship's load plus the full
load of the A/C?. If so, then that's going to put the Kabosh to this
approach because there is not room enough to mount a 2nd 60-100A alt.
(beginning to sound like an onerous task for an electric greenhorn)
I was told that there is some 'new technology' (?) that will take the
output from an externally regulated alternator and split it into 2
separate outputs, one being 12-14v and the other 24-28v. I'm trying to
track this down, just wondering if you had heard anything on this tangent.
Deems Davis # 406
Finishing - ( A Misnomer ! )
http://deemsrv10.com/
Robert L. Nuckolls, III wrote:
>
> No, the SD-20 is a 20amp machine. I'm suspecting that both
> of your 14 volt systems will need to be in the 60 amp class
> or larger. How much power does that a/c compressor need?
>
>
>> Thanks for the information and advice so far and for any additional
>> insight you can provide.
>
>
> This is a MAJOR task. You'll have to fabricate a special
> alternator regulator installation but is all possible.
>
> Bob . . .
>
>
Message 6
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| Subject: | Reasonable qualification for flight hardware? |
11/09/2006
Responding to a previous posting by Dave N6030X <N6030X@DaveMorris.com
Hello Dave Morris, You wrote: "You probably need to find out whether the
FARs on light intensity
apply to experimental aircraft or not."
This is a question that has no clear cut answer. Let's examine the
regulatory issue in the context of exterior lighting:
1) The Operating Limitations for each ABEA (Amateur Built Experimental
Aircraft)** include the following sentence: "After completion of Phase I
flight testing, unless appropriately equipped for night and/or instrument
flight in accordance with 91.205, this aircraft is to be operated under VFR,
day only."
2) To the FAA this sentence means that if the ABEA is operated day VFR that
none of the instrument and equipment requirement provisions of FAR 91.205
would apply.
3) This means that during day VFR operations not even FAR 91.205 (b) (11)
regarding the requirement for an anticollision light system would apply.
4) But as soon as the aircraft is operated at night or in instrument flight,
either day or night, the provisions of FAR 91.205 (b) (11), (c) (2) and (c)
(3) regarding exterior lighting would apply.
5) Each of the subparagraphs listed in 4 above contain the word "approved".
6) But since there are no published certification standards for ABEA there
is no criteria available to measure approval against and one could conclude
that any exterior lighting on an ABEA would be acceptable.
7) But logic raises the issue of interface with other aircraft.## The
purpose of exterior lighting is to permit other observers in the air and on
the ground to see the ABEA and react accordingly. If the ABEA is
inadequately lighted then a hazard to others could exist .
8) This line of reasoning would permit the initial airworthiness inspector
to examine the exterior lighting of the ABEA with regard to its adequacy.
The inspector could conclude, if exterior lighting is present, that the
builder intended to operate the aircraft at night or in instrument
conditions and that therefore some specified level of performance should be
attained by that lighting.
9) A reasonable level of lighting performance to be expected could be
equivalent to that required of type certificated aircraft.
10) It is unlikely that the inspector would have either the equipment or the
inclination to actually measure the exterior lighting performance during his
initial airworthiness inspection.
11) One course of action for the inspector to ensure that the ABEA lighting
installed would meet some accepted performance standard would be for him to
require the ABEA to have installed exterior lighting approved for
installation in type certificated aircraft.
12) The issue may become confused if the builder installs some new
technology lighting (like LED's) that to any unbiased observer is obviously
superior to conventional lighting, but does not carry any kind of FAA
approval marking. To what extent is the initial airworthiness inspector
willing to sign off such lighting?
So I think that the answer to your question: "Do the FARs on light intensity
apply to ABEA or not?" depends upon the actions of the individual initial
airworthiness inspector. It may also be possible that an FAA inspector
during a ramp inspection could raise this issue.
OC -- The best investment we will ever make is in gathering knowledge.
**PS: Some people prefer the more benign sounding, but less precise term,
OBAM (Owner Built And Maintained) aircraft.
##PS: There are other items of ABEA equipment where interface with other
aircraft or the ATC system require specified levels of performance. Some
that come to mind are communication radios, altitude encoders, transponders,
navigation equipment, and ELT's. In most cases the easiest way to ensure
that specified levels of performance will be met is to install approved
equipment such as that marked to meet a TSO (Technical Standard Order)
Time: 09:15:45 AM PST US
From: Dave N6030X <N6030X@DaveMorris.com>
Subject: Re: AeroElectric-List: Reasonable qualification for flight
hardware?
You probably need to find out whether the FARs on light intensity
apply to experimental aircraft or not. Google around a bit, because
some pretty smart people have already done a lot of testing of LEDs
for use in aircraft external lighting.
It is common in the electronics manufacturing world to do "burn-in"
testing for at least 2 or 3 days, during which time the device is
cycled on for a few hours, off for a few hours, preferably including
and possibly exceeding the temperature ranges in which the device is
likely to be operating. Most electronic component failures are
infant-mortality type, meaning that if they survive a few days of
intensive testing, they will probably last a long time.
Dave Morris
Message 7
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| Subject: | Re: Stacked 14v systems for 28v |
Whenever this 28V from 14V subject comes up I implore the adventurous builder to
get the right unit in the first place instead of trying to stuff this beast
into the hole.
Viz.--Buy the right-voltage unit. If there isn't one, call the manufacturer.
Viz.--Modify the unit to run on 12V. Even this is easier than up-converting the
14 volts.
Viz.--Do the whole job another way. Put dry ice in the glovebox, move to Alaska,
open a window...whatever. It's surprising how cool sitting on a seat filled
with silver dollars can be.
Remember, voltage conversion is easy if the power is small. But FORGET IT when
the power gets large. Find some other way.
My two cents.
"When trouble arises and things look bad,
there is always one individual who perceives
a solution and is willing to take command.
Very often, that individual is crazy."
--Dave Barry
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=73387#73387
Message 8
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| Subject: | Reasonable qualification for flight hardware? |
Sent: Thursday, November 09, 2006 9:15 AM
Subject: RE: AeroElectric-List: Reasonable qualification for flight
hardware?
When I was researching this I noted that the Creative Air system is
designed to meet the required FAA light intensity for certified
AC...Thats why you have to angle the LED's in a specified manner as they
are highly directional.
Mind you the best test was when my hangar neighbour was drooling over my
RV and looking at the lights and noting how cool the technology was...I
switched on the position lights for him to see not realising he was
staring straight at the lights....Temporarilly blinded the poor
guy...One could assume the FAA ramp inspector would suffer the same fate
if he doubted their effectiveness...:)
Frank
So I think that the answer to your question: "Do the FARs on light
intensity apply to ABEA or not?" depends upon the actions of the
individual initial airworthiness inspector. It may also be possible that
an FAA inspector during a ramp inspection could raise this issue.
Message 9
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| Subject: | Re: Stacked 14v systems for 28v |
Thanks Eric, I appreciate the input, and I'm beginning to understand
that this is a bigger task, than my limited skills/knowledge will support.
So what about this for an 'approach'
Use 28V alternator (100amp capacity)
28V starter
2 14V batteries connected in series to produce 28V to the A/C
Take a 12-14/v feed off of the 1st battery and use that to drive the
existing 12V electro whizzies.
?
Or should I just sweat and save some $'s
Deems Davis # 406
Finishing - ( A Misnomer ! )
http://deemsrv10.com/
Eric M. Jones wrote:
>
>Whenever this 28V from 14V subject comes up I implore the adventurous builder
to get the right unit in the first place instead of trying to stuff this beast
into the hole.
>
>Viz.--Buy the right-voltage unit. If there isn't one, call the manufacturer.
>
>Viz.--Modify the unit to run on 12V. Even this is easier than up-converting the
14 volts.
>
>Viz.--Do the whole job another way. Put dry ice in the glovebox, move to Alaska,
open a window...whatever. It's surprising how cool sitting on a seat filled
with silver dollars can be.
>
>Remember, voltage conversion is easy if the power is small. But FORGET IT when
the power gets large. Find some other way.
>
>My two cents.
>
>"When trouble arises and things look bad,
>there is always one individual who perceives
>a solution and is willing to take command.
>Very often, that individual is crazy."
> --Dave Barry
>
>--------
>Eric M. Jones
>www.PerihelionDesign.com
>113 Brentwood Drive
>Southbridge, MA 01550
>(508) 764-2072
>emjones@charter.net
>
>
>Read this topic online here:
>
>http://forums.matronics.com/viewtopic.php?p=73387#73387
>
>
>
>
Message 10
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| Subject: | Re: Slick mag P-lead ground wire |
Thanks Bob.
I will ground to the shield this weekend!!!
Duane
> <nuckollsr@cox.net>
>
> At 09:12 AM 11/9/2006 -0500, you wrote:
>
>> <lehmans@sympatico.ca>
>>
>>Bob,
>>
>>I have found a certified aircraft with the P-lead shield grounded at the
>> mag
>>switch end as well as on the mag housing. Is there a down-side (i.e.
>> noise)
>>to grounding the shield at both ends? (Surprisingly, the Maintenance
>> Manual
>>for the aircraft does not include wiring for the mag switch or P-lead.)
>
> There's a number of discussions for p-lead treatment in
>
> http://www.aeroelectric.com/articles/MagnetoSwitchOptions.pdf
>
> and
>
> http://www.aeroelectric.com/FAQ/AeroElectric-List/AeroElectric-List_FAQ.pdf
>
> Open the .pdf files and search on "p-lead".
>
> In a nutshell, for best noise reduction -AND- avoidance of
> a fabricated ground loop, it's best to ground the shield at
> one end only (mag end) and use the shield as the ground return
> for the mag switch as illustrated in the z-figures and cited
> in the two links above.
>
> Bob . . .
>
> ---------------------------------------------------------
> < What is so wonderful about scientific truth...is that >
> < the authority which determines whether there can be >
> < debate or not does not reside in some fraternity of >
> < scientists; nor is it divine. The authority rests >
> < with experiment. >
> < --Lawrence M. Krauss >
> ---------------------------------------------------------
>
>
Message 11
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| Subject: | Re: 'Scope offer from Saelig |
Hi Bob,
Just wondering what you think of the 'scope after a few months?
Thanks, Joe
Robert L. Nuckolls, III wrote:
> <nuckollsr@cox.net>
>
> A few days ago I mentioned an oscilloscope being offered by
> Saelig at:
>
> http://saelig.com/
>
> I just received the one I had on order. It's a rough clone
> of the Tektronix TDS200 series scopes. Only 25 Mhz but it's
> in color. Comes with two probes ($50 value alone). The USB
> cable and attending software lets you dump both image and
> tabular data to a computer. Here's the test setup on my
> bench.
>
> http://www.aeroelectric.com/Pictures/Tools/PDS5022S_OWON_Scope.jpg
>
> Once the data has been dumped to the computer it can be manipulated
> in a variety of ways including print to hard copy. Haven't had
> occasion to do any serious measurements but I can say that for
> $299, it's a hell-of-a-buy.
>
> I'm going to use it as my 'beater' scope to drag around
> for looking into problems on airplanes and save my Tek
> for less stressful bench work.
>
>
>
> Bob . . .
>
>
Message 12
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| Subject: | Re: Stacked 14v systems for 28v |
Unfortunately, unless the other electrowhizzies are very low amperage,
you will be forever overcharging the second battery with this arrangement.
Depending what the amp draw of your other 12V electrowhizzies are you
might try using a 28V to 14V converter for them. Also, be aware that a
lot of the newer electrowhizzies will run from 12-28V so you could run
those off the 28V.
Depending on your mix of electronics you might be able to run the
majority off the 28V and run a few low draw units from the second
battery or from a small 28 to 14V converter.
There are certainly ways to do what you want to do, but I suspect that
you may end up sweating...
Dick Tasker
Deems Davis wrote:
>
> Thanks Eric, I appreciate the input, and I'm beginning to understand
> that this is a bigger task, than my limited skills/knowledge will
> support.
> So what about this for an 'approach'
>
> Use 28V alternator (100amp capacity)
> 28V starter
> 2 14V batteries connected in series to produce 28V to the A/C
> Take a 12-14/v feed off of the 1st battery and use that to drive the
> existing 12V electro whizzies.
>
> ?
>
>
> Or should I just sweat and save some $'s
>
> Deems Davis # 406
> Finishing - ( A Misnomer ! )
> http://deemsrv10.com/
>
>
> Eric M. Jones wrote:
>
>> <emjones@charter.net>
>>
>> Whenever this 28V from 14V subject comes up I implore the adventurous
>> builder to get the right unit in the first place instead of trying to
>> stuff this beast into the hole.
>>
>> Viz.--Buy the right-voltage unit. If there isn't one, call the
>> manufacturer.
>>
>> Viz.--Modify the unit to run on 12V. Even this is easier than
>> up-converting the 14 volts.
>>
>> Viz.--Do the whole job another way. Put dry ice in the glovebox, move
>> to Alaska, open a window...whatever. It's surprising how cool
>> sitting on a seat filled with silver dollars can be.
>> Remember, voltage conversion is easy if the power is small. But
>> FORGET IT when the power gets large. Find some other way.
>>
>> My two cents.
>>
>> "When trouble arises and things look bad,
>> there is always one individual who perceives
>> a solution and is willing to take command.
>> Very often, that individual is crazy."
>> --Dave Barry
>>
>> --------
>> Eric M. Jones
>> www.PerihelionDesign.com
>> 113 Brentwood Drive
>> Southbridge, MA 01550
>> (508) 764-2072
>> emjones@charter.net
>>
>>
>>
>>
>> Read this topic online here:
>>
>> http://forums.matronics.com/viewtopic.php?p=73387#73387
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
Message 13
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| Subject: | Re: Stacked 14v systems for 28v |
If you Google "12 volt air conditioner" you get a boatload of hits. I'd search
very hard for a 12V solution on the internet.
Consider that almost all 12V cars have air conditioners--with the compressor running
off the engine. Do you need a huge electric motor to keep cool when the
engine is not running? Is this a mode of operation important to you? Better an
engine-driven compressor than a second alternator.
They used to use ground a/c. Could your operation do this?
I come at this question from a desire to minimize weight and complexity. My air
conditioning comes from the big fan in the nose. This may not be where you are
coming from.
"Nothing is too wonderful to be true."
James Clerk Maxwell, discoverer of electromagnetism
"Too much of a good thing can be wonderful."
Mae West, discoverer of personal magnetism
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=73420#73420
Message 14
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Howdy those-that-know-
I am (as usual) trying something I know little about, but he'p me out here,
purty please!
Goal: light an annunciator LED when Trutrak servos are OFF. This is a
reminder that Digiflight is not flying the airplane. Normal condition is A/P on
for
normal flight with LED OFF.
Suggestion from Trutrak: connect NPN Darlington transistor base via a 10K
resistor to servo torque line on servo connector (pin 6- common to pin 4 or 16
on
back of Digitrak depending on pitch or roll servo) . Connect 12v to
annunciator LED+, LED ground to emitter and use transistor collector to ground
lamp.
If I got this right, the signal from the servo turns transistor on, completing
LED circuit, LED comes ON.
Problem is, Trutrak offered no guidance beyond "Darlington NPN transistor"
and I have googled, Digikeyed & Mousered trying to find an appropriate
transistor. The values are mystifying and require much research & education to
demystify. Best quess is this one in a TO-92 package:
http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=488&M=2N6426G
Supposing this is a good choice to turn the LED ON, can I turn the LED OFF by
using this transistor circuit to turn on a small relay and use relay N.C.
contacts connected to LED ground to turn off the LED when servo is energized, and
if so, what would be an appropriate relay?
Or is there a better way to do this?
I humble myself before y'all but THANKS just the same for any advice!
Mark Phillips
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