Today's Message Index:
----------------------
1. 03:13 AM - ELT antenna inside tube and fabric fuselage (John Ciolino)
2. 04:54 AM - Re: ELT antenna inside tube and fabric fuselage (Jared Yates)
3. 05:35 AM - Re: ELT antenna inside tube and fabric fuselage (John Ciolino)
4. 05:54 AM - Re: ATC slo blo? (racerjerry)
5. 05:57 AM - Re: ELT antenna inside tube and fabric fuselage (Robert L. Nuckolls, III)
6. 05:57 AM - Re: ATC slo blo? (Robert L. Nuckolls, III)
7. 07:22 AM - Re: ELT antenna inside tube and fabric fuselage (Bill Putney)
8. 07:50 AM - Re: ELT antenna inside tube and fabric fuselage (Ken)
9. 08:21 AM - Re: ELT antenna inside tube and fabric fuselage (Robert L. Nuckolls, III)
10. 09:28 AM - Re: ATC slo blo? (B Tomm)
11. 09:36 AM - Re: ELT antenna inside tube and fabric fuselage (Jared Yates)
12. 10:21 AM - Re: ATC slo blo? (B Tomm)
13. 11:29 AM - Re: ELT antenna inside tube and fabric fuselage (Robert L. Nuckolls, III)
14. 12:55 PM - Re: ATC slo blo? (Robert L. Nuckolls, III)
15. 01:16 PM - Re: ELT antenna inside tube and fabric fuselage (James Kilford)
16. 01:20 PM - Re: ELT antenna inside tube and fabric fuselage (James Kilford)
17. 02:45 PM - Re: ELT antenna inside tube and fabric fuselage (Jared Yates)
18. 03:42 PM - Re: ELT antenna inside tube and fabric fuselage (The Kuffels)
19. 03:49 PM - Re: ELT antenna inside tube and fabric fuselage (Ed Holyoke)
20. 04:19 PM - Re: ATC slo blo? (Ed Holyoke)
21. 08:03 PM - Re: ATC slo blo? (Tim Andres)
22. 08:07 PM - Re: ATC slo blo? (B Tomm)
23. 09:13 PM - Re: ATC slo blo? (B Tomm)
24. 09:47 PM - Re: ATC slo blo? (Tim Andres)
Message 1
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Subject: | ELT antenna inside tube and fabric fuselage |
I am building a Legend Cub and intend to cover using the Poly-fiber process.
That process uses a coat of aluminum pigmented dope (Poly-Spray) as UV
protection.
I want to install the Comm and ELT antennas inside the fuselage, and ACK
(ELT) says that can be done as long as the fabric is "of a non-conductive
nature". I asked ACK if the Poly-Spray would be non-conductive. They
thought it would be OK but referred me to Poly-fiber.
Poly-fiber says the ELT antenna would be OK inside the fuselage but mount
the Comm antenna outside. Several posters on the J-3cub.com site have
reported good results using a dipole antenna inside the fuselage so the
Poly-fiber advice does not seem right.
Has anyone had experience with antennas inside a Poly-fiber fuselage?
Thanks
John Ciolino
Message 2
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Subject: | Re: ELT antenna inside tube and fabric fuselage |
The polyspray might not be a concern, but what about the tubes? Are they st
eel?
On Mar 7, 2013, at 6:12, "John Ciolino" <JohnCiolino@carolina.rr.com> wrote:
> I am building a Legend Cub and intend to cover using the Poly-fiber proces
s. That process uses a coat of aluminum pigmented dope (Poly-Spray) as UV p
rotection.
>
> I want to install the Comm and ELT antennas inside the fuselage, and ACK (
ELT) says that can be done as long as the fabric is =9Cof a non-conduc
tive nature=9D. I asked ACK if the Poly-Spray would be non-conductive
. They thought it would be OK but referred me to Poly-fiber.
>
> Poly-fiber says the ELT antenna would be OK inside the fuselage but mount t
he Comm antenna outside. Several posters on the J-3cub.com site have reporte
d good results using a dipole antenna inside the fuselage so the Poly-fiber a
dvice does not seem right.
>
> Has anyone had experience with antennas inside a Poly-fiber fuselage?
>
> Thanks
> John Ciolino
>
>
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Message 3
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Subject: | ELT antenna inside tube and fabric fuselage |
They are, but according to posters on the J-sCub.com site Comm radio
reception and transmit is very good with a dipole antenna from Advance
Aircraft Electronics mounted inside. No one has addressed the ELT
antenna but as I mentioned the ACK folks say installation inside of a
(steel) tube and fabric fuselage will meet their criteria if the fabric
is non-conductive.
I am just not sure if the Poly-Spray coating makes the fabric
conductive; apparently the steel tubes are not a factor. The ELT
antenna probably has a better chance of survival inside the fuselage in
the event of a crash.
John Ciolino
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Jared
Yates
Sent: Thursday, March 07, 2013 7:54 AM
Subject: Re: AeroElectric-List: ELT antenna inside tube and fabric
fuselage
The polyspray might not be a concern, but what about the tubes? Are
they steel?
On Mar 7, 2013, at 6:12, "John Ciolino" <JohnCiolino@carolina.rr.com>
wrote:
I am building a Legend Cub and intend to cover using the Poly-fiber
process. That process uses a coat of aluminum pigmented dope
(Poly-Spray) as UV protection.
I want to install the Comm and ELT antennas inside the fuselage, and ACK
(ELT) says that can be done as long as the fabric is =9Cof a
non-conductive nature=9D. I asked ACK if the Poly-Spray would be
non-conductive. They thought it would be OK but referred me to
Poly-fiber.
Poly-fiber says the ELT antenna would be OK inside the fuselage but
mount the Comm antenna outside. Several posters on the J-3cub.com site
have reported good results using a dipole antenna inside the fuselage so
the Poly-fiber advice does not seem right.
Has anyone had experience with antennas inside a Poly-fiber fuselage?
Thanks
John Ciolino
=========
st">http://www.matronics.com/Navigator?AeroElectric-List
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cs.com
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matronics.com/contribution
=========
Message 4
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Subject: | Re: ATC slo blo? |
NO. Slow Blow not available in ATC format. ATC, by specification, is a fast
acting low voltage automotive blade type fuse.
--------
Jerry King
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=395807#395807
Message 5
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Subject: | ELT antenna inside tube and fabric fuselage |
At 07:34 AM 3/7/2013, you wrote:
>They are, but according to posters on the
>J-sCub.com site Comm radio reception and
>transmit is very good with a dipole antenna from
>Advance Aircraft Electronics mounted
>inside.=C2 No one has addressed the ELT antenna
>but as I mentioned the ACK folks say
>installation inside of a (steel) tube and fabric
>fuselage will meet their criteria if the fabric is non-conductive.
Interesting. I'm surprised that they would
climb out on that 'limb' unless their tests
for achieving TSO status included that
configuration . . . which I doubt.
Discussions like this are fraught with
the effects of variables that are unknown
and therefore cannot be part of the
deliberations. I do know that the uhf
signal is less likely to be severely
trashed by a surrounding, open mesh
'cage'. It would be interesting to
conduct some A-B experiments comparing
an internal antenna with an external
antenna with the assistance of some hams
having 70 cm radios and some rudimentary
tools for comparing signal strengths.
But suppose you deduced that for most
situations, the internal antenna was about
10 db down from the external one. Now what?
By what criteria is acceptability to be
judged? Without knowing the system's margins
for performance under various signal levels,
having such numbers doesn't go much beyond
'interesting'.
Be wary of advice that does not come from
someone who has access to applicable data
and knows how to interpret it. This applies
especially to individuals in the employ of
regulatory agencies who can exert power over
your activities.
The reports from fellow pilots about the
performance of internally mounted VHF antennas
is interesting. It's great if the installation
meets their communications needs. But their
observations are not quantified data. The
up side is that the physics is on your side.
The UHF feature on the modern ELT will be BETTER
disposed to adequate performance than the
VHF comm antenna.
The off-hand advice from folks without
numbers may NOT be on your side.
Bob . . .
Message 6
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Subject: | Re: ATC slo blo? |
At 10:35 PM 3/6/2013, you wrote:
>
>
>Is there such a thing as a slow blow fuse in an ATC format (for a fuse
>block)?
No. What is the situation for which you perceive
a need for such a fuse?
Bob . . .
Message 7
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Subject: | Re: ELT antenna inside tube and fabric fuselage |
I'd mount all the antenna's outside. If there's enough aluminum in the
dope to protect the fabric from UV, it's going to be pretty reflective
of the RF from the radios. To much reflected power back into the antenna
can damage transmitters. Having your ELT inside, at the very least, is
going to reduce the range and make you harder to find.
Just my opinion from being an A&P/IA who's installed a lot of radios and
an Extra Class Ham as well as Chief Engineer at a few FM broadcast stations.
Bill
On 3/7/13 3:12 AM, John Ciolino wrote:
>
> I am building a Legend Cub and intend to cover using the Poly-fiber
> process. That process uses a coat of aluminum pigmented dope
> (Poly-Spray) as UV protection.
>
> I want to install the Comm and ELT antennas inside the fuselage, and
> ACK (ELT) says that can be done as long as the fabric is "of a
> non-conductive nature". I asked ACK if the Poly-Spray would be
> non-conductive. They thought it would be OK but referred me to Poly-fiber.
>
> Poly-fiber says the ELT antenna would be OK inside the fuselage but
> mount the Comm antenna outside. Several posters on the J-3cub.com site
> have reported good results using a dipole antenna inside the fuselage
> so the Poly-fiber advice does not seem right.
>
> Has anyone had experience with antennas inside a Poly-fiber fuselage?
>
> Thanks
>
> John Ciolino
>
> *
>
>
> *
Message 8
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Subject: | Re: ELT antenna inside tube and fabric fuselage |
An external antenna might reduce occupant exposure to additional RF
transmission energy if that is a concern to someone. Might also reduce
the rare RF caused instrumentation glitches that have been reported here.
Just a wild guess.
Ken
On 07/03/2013 8:56 AM, Robert L. Nuckolls, III wrote:
> At 07:34 AM 3/7/2013, you wrote:
>> They are, but according to posters on the J-sCub.com site Comm radio
>> reception and transmit is very good with a dipole antenna from Advance
>> Aircraft Electronics mounted inside. No one has addressed the ELT
>> antenna but as I mentioned the ACK folks say installation inside of a
>> (steel) tube and fabric fuselage will meet their criteria if the
>> fabric is non-conductive. **
>
> Interesting. I'm surprised that they would
> climb out on that 'limb' unless their tests
> for achieving TSO status included that
> configuration . . . which I doubt.
>
> Discussions like this are fraught with
> the effects of variables that are unknown
> and therefore cannot be part of the
> deliberations. I do know that the uhf
> signal is less likely to be severely
> trashed by a surrounding, open mesh
> 'cage'. It would be interesting to
> conduct some A-B experiments comparing
> an internal antenna with an external
> antenna with the assistance of some hams
> having 70 cm radios and some rudimentary
> tools for comparing signal strengths.
>
> But suppose you deduced that for most
> situations, the internal antenna was about
> 10 db down from the external one. Now what?
> By what criteria is acceptability to be
> judged? Without knowing the system's margins
> for performance under various signal levels,
> having such numbers doesn't go much beyond
> 'interesting'.
>
> Be wary of advice that does not come from
> someone who has access to applicable data
> and knows how to interpret it. This applies
> especially to individuals in the employ of
> regulatory agencies who can exert power over
> your activities.
>
> The reports from fellow pilots about the
> performance of internally mounted VHF antennas
> is interesting. It's great if the installation
> meets their communications needs. But their
> observations are not quantified data. The
> up side is that the physics is on your side.
> The UHF feature on the modern ELT will be BETTER
> disposed to adequate performance than the
> VHF comm antenna.
>
> The off-hand advice from folks without
> numbers may NOT be on your side.
>
> Bob . . .
Message 9
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Subject: | Re: ELT antenna inside tube and fabric fuselage |
At 09:20 AM 3/7/2013, you wrote:
>I'd mount all the antenna's outside. If there's enough aluminum in
>the dope to protect the fabric from UV, it's going to be pretty
>reflective of the RF from the radios. To much reflected power back
>into the antenna can damage transmitters. Having your ELT inside, at
>the very least, is going to reduce the range and make you harder to find.
The effects of suspended metal in aircraft
fabric finishes has been a point of debate
for years. It would be interesting to do some
experiments to explore real effects.
If anyone has the materials on hand to "finish"
an experimental enclosure (about the size of a
shoe box) as if it were a rag cover, I'd be
willing to use said enclosure to make some
shade tree measurements on radiation effects.
Further, having such a test article on hand
would offer an opportunity to do some lab
measurements at some time in the future wherein
I have access to the facilities.
If somebody can help produce the test enclosure,
drop me a note and let's discuss materials
and techniques. Thanks!
Bob . . .
Message 10
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Hi Bob,
My P-mag manual says to use a breaker or slow blow fuse. I have already
wired the P-mags to a fuse block (ATC) and my field of breakers is already
full.
So plan B will be to replace the switches that control the power to the
P-mags with switch-breakers (5 amp) and replace the fuses with a max high
value to protect the wire to the switch-breakers.
The fuse size to protect 18 AWG wire (about 5 foot long), 10 or 15 amp?
(fast acting ATC).
Bevan
RV7A
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Thursday, March 07, 2013 5:57 AM
Subject: Re: AeroElectric-List: ATC slo blo?
--> <nuckolls.bob@aeroelectric.com>
At 10:35 PM 3/6/2013, you wrote:
>--> <fvalarm@rapidnet.net>
>
>
>Is there such a thing as a slow blow fuse in an ATC format (for a fuse
>block)?
No. What is the situation for which you perceive
a need for such a fuse?
Bob . . .
Message 11
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Subject: | Re: ELT antenna inside tube and fabric fuselage |
I have polyfiber leftovers to cover a box like that, and could use the opportunity
as a covering demo/training for someone else.
On Mar 7, 2013, at 11:20, "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
wrote:
>
> At 09:20 AM 3/7/2013, you wrote:
>> I'd mount all the antenna's outside. If there's enough aluminum in the dope
to protect the fabric from UV, it's going to be pretty reflective of the RF from
the radios. To much reflected power back into the antenna can damage transmitters.
Having your ELT inside, at the very least, is going to reduce the range
and make you harder to find.
>
> The effects of suspended metal in aircraft
> fabric finishes has been a point of debate
> for years. It would be interesting to do some
> experiments to explore real effects.
>
> If anyone has the materials on hand to "finish"
> an experimental enclosure (about the size of a
> shoe box) as if it were a rag cover, I'd be
> willing to use said enclosure to make some
> shade tree measurements on radiation effects.
>
> Further, having such a test article on hand
> would offer an opportunity to do some lab
> measurements at some time in the future wherein
> I have access to the facilities.
>
> If somebody can help produce the test enclosure,
> drop me a note and let's discuss materials
> and techniques. Thanks!
>
>
>
> Bob . . .
>
>
>
>
Message 12
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OK,
Maybe my memory has been fading. To clarify, the P-mags instructions say to
use a breaker (in another area they suggest a pullable breaker) and a switch
to control power to the P-mags. I may have got the fuse idea from the
Z-drawings for electronic ignition. Anyway...
I currently have 5-amp fuses in the always hot battery bus feeding the P-mag
power control switches. These switches in turn feed the power inputs of the
P-mags.
So the easy fix would be to replace the switches with a switch/breakers, and
replace the fuses protecting the feed to the switch with a higher value ATC
such as 10-15 amp. It's a 18 AWG wire all the way from the fuse block to
the P-mags. Each P-mag has it's own independent circuit, fuse, wire and
switch.
Bob, I would like to use the highest value fuse possible ahead of the switch
breaker. It is not supposed to trip unless the wire to the switch faults
hard. Could this be 15 amp?
Bevan
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Thursday, March 07, 2013 5:57 AM
Subject: Re: AeroElectric-List: ATC slo blo?
--> <nuckolls.bob@aeroelectric.com>
At 10:35 PM 3/6/2013, you wrote:
>--> <fvalarm@rapidnet.net>
>
>
>Is there such a thing as a slow blow fuse in an ATC format (for a fuse
>block)?
No. What is the situation for which you perceive
a need for such a fuse?
Bob . . .
Message 13
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Subject: | Re: ELT antenna inside tube and fabric fuselage |
At 11:36 AM 3/7/2013, you wrote:
>
>I have polyfiber leftovers to cover a box like that, and could use
>the opportunity as a covering demo/training for someone else.
>
Great. I'm mulling over the geometry of a
polyfiber 'test cell' that would facilitate
relative attenuation measurements on a range
of antennas. Structure for the cell should
be RF transparent.
I'm thinking of a cylindrical tube on the
order of 6" diameter and 48" long covered
with exemplar polyfiber finished fabric.
Emacs!
The tube would have a single split-cut over
half the length to a mast clearance hole in
the middle. This would allow it to be
slipped over dipole antennas covering our
range of interest. I'm thinking of tests at
130, 330, and 1000 Mhz which can be generated
and measured with equipment I have.
I wonder if a cardboard tube of the smallest practice
thickness could be used as a former. I considered
plastic DWV pipe . . . but these materials have some
degree of RF opacity. I guess we could have two
such tubes, one that's covered and one that is
not covered. That would wash out effects of the
plastic in the sandwich layers. Your thoughts
and the thoughts of others are welcome.
I'm negotiating a business arrangement
with a OBAM aircraft magazine to do a regular
flow of articles. This experiment might provide
the 'meat' for a first article .
Bob . . .
Message 14
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At 12:19 PM 3/7/2013, you wrote:
>
>OK,
>
>Maybe my memory has been fading. To clarify, the P-mags instructions say to
>use a breaker (in another area they suggest a pullable breaker) and a switch
>to control power to the P-mags. I may have got the fuse idea from the
>Z-drawings for electronic ignition. Anyway...
>
>I currently have 5-amp fuses in the always hot battery bus feeding the P-mag
>power control switches. These switches in turn feed the power inputs of the
>P-mags.
>
>So the easy fix would be to replace the switches with a switch/breakers, and
>replace the fuses protecting the feed to the switch with a higher value ATC
>such as 10-15 amp. It's a 18 AWG wire all the way from the fuse block to
>the P-mags. Each P-mag has it's own independent circuit, fuse, wire and
>switch.
>
>Bob, I would like to use the highest value fuse possible ahead of the switch
>breaker. It is not supposed to trip unless the wire to the switch faults
>hard. Could this be 15 amp?
I think you're getting wrapped around the worry-axle my
friend. A p-mag needs power only to get an engine started
and to operate at idle/taxi rpms. After that, it runs
nicely on internal power alone.
During any given tank full of fuel, what's the likelihood of loosing
all 4 power sources for the pair of p-mags? They're PM alternators.
Further, they take very little power from the bus. Ordinary 5A fuses
to the e-bus are plenty robust.
Referring to the Emagair literature we see:
Emacs!
Current draw for this system at max RPM is only 0.25 amps! There are no
inrush currents associated powering up this system. From a systems perspective,
they would like to have +12 available all the time. There's no reason
to 'switch
the supply on and off except to test the internal power source . . . which
is exceedingly reliable.
If it were my airplane, I'd run the p-mags from the e-bus through
5A fuses and no switches. Also, 20AWG wire is plenty robust. Treat
them just as you would a magneto for engine control and pre-flight
testing of ignition systems. Periodically check internal power sources
by powering the e-bus down and make sure the engine runs at
RPM above 1500 with the opposite system turned OFF. This checks
internal sources. Power the e-bus back up and check to see that
the engine will start with a single p-mag switched ON . . . then
check the other. This will spot a 'missing' dc power path. Do it
at each oil change interval.
I wouldn't spend a lot of time crafting a 'golden' source of
DC power. Risks to the aircraft and occupants due to loss of
any one feature is zero, risk for loss of all 4 in any 4-hour
period is vanishingly small.
Bob . . .
Message 15
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Subject: | Re: ELT antenna inside tube and fabric fuselage |
Hi John,
Here's a note from some time ago about some tests when I covered my plane
with PolyFiber. You can find the full thread online, it was from about June
6 201. Bottom line: PolySpray didn't seem to make any difference...
HTH.
James
*
Gents,
I had been wondering, for some time, what to do about the PolyFiber
PolySpray coats. PolySpray is a metal-loaded paint that is used to
protect PolyFiber fabric from UV damage.
I'd wanted to put all the aerials inside my fuselage, but was
concerned that the PolySpray would attenuate radio signals to/from
COM, NAV, GPS (especially) and XPNDR. PolyFiber's own advice was to
put the aerials outside the fuselage, and to definitely use the
PolySpray coating, to ensure longevity of fabric (apparently the
PolySpray increases the fabric's life 4-fold!).
To cut a long story short, I decided to chance it -- with PolySpray
and internal aerials -- and see what happened, figuring that I could
move the aerials outside the fuselage if necessary.
Today, I did tests to see if the aerials function as I would wish, an
d
they did. The PolySpray coats appear to have made no difference to
the signals -- even the presumably very small GPS signal. I don't
have anything in the way of scientific instruments, just the signal
strength shown on the GPS and hand-held radio, but using the
fuselage-mounted aerials makes no discernible difference to the signa
l
strength compared to the equipment's own aerials. I've yet to test
the NAV / XPNDR aerials, but I assume the same will hold true for
those too.
FWIW!
James
*
On 7 March 2013 11:12, John Ciolino <JohnCiolino@carolina.rr.com> wrote:
> I am building a Legend Cub and intend to cover using the Poly-fiber
> process. That process uses a coat of aluminum pigmented dope (Poly-Spray
)
> as UV protection.****
>
> ** **
>
> I want to install the Comm and ELT antennas inside the fuselage, and ACK
> (ELT) says that can be done as long as the fabric is =9Cof a non-co
nductive
> nature=9D. I asked ACK if the Poly-Spray would be non-conductive.
They
> thought it would be OK but referred me to Poly-fiber.****
>
> ** **
>
> Poly-fiber says the ELT antenna would be OK inside the fuselage but mount
> the Comm antenna outside. Several posters on the J-3cub.com site have
> reported good results using a dipole antenna inside the fuselage so the
> Poly-fiber advice does not seem right. ****
>
> ** **
>
> Has anyone had experience with antennas inside a Poly-fiber fuselage?****
>
> ** **
>
> Thanks****
>
> John Ciolino****
>
> *
>
===========
===========
===========
===========
> *
>
>
Message 16
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Subject: | Re: ELT antenna inside tube and fabric fuselage |
That would be terrific! It's a question that's asked quite a lot, and
consistent repeatable tests would be terrific.
The guys at PolyFiber have always seemed very decent when I've met them and
I wouldn't be surprised if they would be willing to help by supplying
product or a suitable test frame.
James
On 7 March 2013 19:28, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 11:36 AM 3/7/2013, you wrote:
>
> >
>
> I have polyfiber leftovers to cover a box like that, and could use the
> opportunity as a covering demo/training for someone else.
>
>
> Great. I'm mulling over the geometry of a
> polyfiber 'test cell' that would facilitate
> relative attenuation measurements on a range
> of antennas. Structure for the cell should
> be RF transparent.
>
> I'm thinking of a cylindrical tube on the
> order of 6" diameter and 48" long covered
> with exemplar polyfiber finished fabric.
>
> [image: Emacs!]
>
>
> The tube would have a single split-cut over
> half the length to a mast clearance hole in
> the middle. This would allow it to be
> slipped over dipole antennas covering our
> range of interest. I'm thinking of tests at
> 130, 330, and 1000 Mhz which can be generated
> and measured with equipment I have.
>
> I wonder if a cardboard tube of the smallest practice
> thickness could be used as a former. I considered
> plastic DWV pipe . . . but these materials have some
> degree of RF opacity. I guess we could have two
> such tubes, one that's covered and one that is
> not covered. That would wash out effects of the
> plastic in the sandwich layers. Your thoughts
> and the thoughts of others are welcome.
>
> I'm negotiating a business arrangement
> with a OBAM aircraft magazine to do a regular
> flow of articles. This experiment might provide
> the 'meat' for a first article .
>
>
> **
>
> ** Bob . . .
>
Message 17
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Subject: | Re: ELT antenna inside tube and fabric fuselage |
I don't know anything about the RF aspect, but what about two 4" pvc drain p
ipes, one bare and one coated with poly spray? If the coating is the target
variable, that would pretty well isolate it. Another easy to find source
would be a cardboard shipping tube, either circular in cross section or tri
angular.
On Mar 7, 2013, at 14:28, "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectr
ic.com> wrote:
> At 11:36 AM 3/7/2013, you wrote:
m>
>>
>> I have polyfiber leftovers to cover a box like that, and could use the op
portunity as a covering demo/training for someone else.
>
> Great. I'm mulling over the geometry of a
> polyfiber 'test cell' that would facilitate
> relative attenuation measurements on a range
> of antennas. Structure for the cell should
> be RF transparent.
>
> I'm thinking of a cylindrical tube on the
> order of 6" diameter and 48" long covered
> with exemplar polyfiber finished fabric.
>
> <ef90626.jpg>
>
>
> The tube would have a single split-cut over
> half the length to a mast clearance hole in
> the middle. This would allow it to be
> slipped over dipole antennas covering our
> range of interest. I'm thinking of tests at
> 130, 330, and 1000 Mhz which can be generated
> and measured with equipment I have.
>
> I wonder if a cardboard tube of the smallest practice
> thickness could be used as a former. I considered
> plastic DWV pipe . . . but these materials have some
> degree of RF opacity. I guess we could have two
> such tubes, one that's covered and one that is
> not covered. That would wash out effects of the
> plastic in the sandwich layers. Your thoughts
> and the thoughts of others are welcome.
>
> I'm negotiating a business arrangement
> with a OBAM aircraft magazine to do a regular
> flow of articles. This experiment might provide
> the 'meat' for a first article .
>
>
> Bob . . .
Message 18
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Subject: | Re: ELT antenna inside tube and fabric fuselage |
Bill Putney says:
<< I'd mount all the antenna's outside. .. To much reflected power back
into the antenna can damage transmitters. Having your ELT inside, at the
very least, is going to reduce the range and make you harder to find. >>
Bill is right, outside is best. Except for the ELT. My direct
experience is having the ELT antenna outside leads to it often being
removed during the crash which really reduces your range. Even with
metal aircraft I recommend it be mounted inside but "visible" through
the canopy/windows, etc. For example, on a friend's Zenith 701 we put
the ELT in the middle of the instrument panel cover just behind the
windshield. While such a location is far from ideal in a perfect
propagation sense, data says if the crash is survivable then the
internal antenna has enough performance for satellite pickup.
Don't have data for putting the antenna inside a tube framework. But
basic radio theory says if there is enough leakage for the 121.5MHz
signal to be heard then there is certainly enough leakage for the 406MHz
signal. Try it and see. Limit any transmitter test to less than 30
seconds sometime between zero and five minutes past the hour.
Must disagree with the notion a proper antenna, even detuned by
surroundings, can ever reflect enough power to damage a modern ELT
transmitter. Am not aware of any ELT which can't tolerate 100% power
reflection. This is what happens when an antenna is disconnected and
the ELT is accidentally turned on.
Tom Kuffel
Since Bill noted his qualifications here are some of mine only partly
tongue in cheek: CFI, search & rescue pilot (200+), Amateur Extra,
former FCC First Class Phone, only Engineer not Chief Engineer at my FM
station but it was over 50 years ago.
Message 19
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Subject: | Re: ELT antenna inside tube and fabric fuselage |
Message 20
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Subject: | Re: ATC slo blo? |
Message 21
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Subject: | Re: ATC slo blo? |
Ummm, check me but I'm pretty sure the power to the PMAG is protected with a pull-able
breaker or other, but it does not run power thru the switch. Also, you
want the power from the switched side of the master relay not the always hot
bus as you indicated because the PMAG draws power even when switched off via the
P lead.
The switch operates just as a P lead to kill the ignition, but it does not interrupt
power to the unit.
A pull-able breaker is desired so you can check the internal alternator function
as part of your run up. Pull the breaker, kill the other ignition and it should
keep running.
One other tip, be sure to pull the breaker when using a battery charger, PMAGs
have had problems and its mentioned in the manual.
Tim
Sent from my iPad
On Mar 7, 2013, at 10:19 AM, "B Tomm" <fvalarm@rapidnet.net> wrote:
>
> Anyway...
>
> I currently have 5-amp fuses in the always hot battery bus feeding the P-mag
> power control switches. These switches in turn feed the power inputs of the
> P-mags.
>
> So the easy fix would be to replace the switches with a switch/breakers, and
> replace the fuses protecting the feed to the switch with a higher value ATC
> such as 10-15 amp. It's a 18 AWG wire all the way from the fuse block to
> the P-mags. Each P-mag has it's own independent circuit, fuse, wire and
> switch.
>
>
>
>
Message 22
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OK,
Thanks Bob,
I will leave things as they. Thanks for your time.
Bevan
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Thursday, March 07, 2013 12:52 PM
Subject: RE: AeroElectric-List: ATC slo blo?
At 12:19 PM 3/7/2013, you wrote:
OK,
Maybe my memory has been fading. To clarify, the P-mags instructions say to
use a breaker (in another area they suggest a pullable breaker) and a switch
to control power to the P-mags. I may have got the fuse idea from the
Z-drawings for electronic ignition. Anyway...
I currently have 5-amp fuses in the always hot battery bus feeding the P-mag
power control switches. These switches in turn feed the power inputs of the
P-mags.
So the easy fix would be to replace the switches with a switch/breakers, and
replace the fuses protecting the feed to the switch with a higher value ATC
such as 10-15 amp. It's a 18 AWG wire all the way from the fuse block to
the P-mags. Each P-mag has it's own independent circuit, fuse, wire and
switch.
Bob, I would like to use the highest value fuse possible ahead of the switch
breaker. It is not supposed to trip unless the wire to the switch faults
hard. Could this be 15 amp?
I think you're getting wrapped around the worry-axle my
friend. A p-mag needs power only to get an engine started
and to operate at idle/taxi rpms. After that, it runs
nicely on internal power alone.
During any given tank full of fuel, what's the likelihood of loosing
all 4 power sources for the pair of p-mags? They're PM alternators.
Further, they take very little power from the bus. Ordinary 5A fuses
to the e-bus are plenty robust.
Referring to the Emagair literature we see:
Emacs!
Current draw for this system at max RPM is only 0.25 amps! There are no
inrush currents associated powering up this system. From a systems
perspective,
they would like to have +12 available all the time. There's no reason to
'switch
the supply on and off except to test the internal power source . . . which
is exceedingly reliable.
If it were my airplane, I'd run the p-mags from the e-bus through
5A fuses and no switches. Also, 20AWG wire is plenty robust. Treat
them just as you would a magneto for engine control and pre-flight
testing of ignition systems. Periodically check internal power sources
by powering the e-bus down and make sure the engine runs at
RPM above 1500 with the opposite system turned OFF. This checks
internal sources. Power the e-bus back up and check to see that
the engine will start with a single p-mag switched ON . . . then
check the other. This will spot a 'missing' dc power path. Do it
at each oil change interval.
I wouldn't spend a lot of time crafting a 'golden' source of
DC power. Risks to the aircraft and occupants due to loss of
any one feature is zero, risk for loss of all 4 in any 4-hour
period is vanishingly small.
Bob . . .
Message 23
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Thanks Tim.
I understand the drawing from Emagair, and Bob's comment makes sense to me.
I have a very non-standard (comprehensive) electrical system. It includes a
very small always hot bus located 6 inches from the battery. This bus
supplies power (via two independent circuits) to the P-mag power switches,
not to be confused with the magneto kill switches (which are part of the
keyed ignition). These switches must be turned on or the engine will not
start. These switches are the ones you would turn off to test the internal
alternators (periodically, not on each runup). They are also turned off at
the end of flight, otherwise the battery will run down.
This is how I have chosen to build my system and flows well with the rest of
my electrical system. I know it is not for everyone, but I have like the
way I have it.
My original question came up as I was told (and I believed) that the P-mags
should have a breaker/switch and not fuse/switch. With the very small
current flows according to Bob M, (the Emagair spec sheet does not indicate
current flow), and no unusually high inrush currents, fuses should be fine
as long as I also have switches to power down the mags.
On the other hand, my WigWag module (by Sound Off Signal) is solid state and
does require a fast acting fuse to protect the controller portion, but
that's a story for another day.
Bevan
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Tim
Andres
Sent: Thursday, March 07, 2013 8:02 PM
Subject: Re: AeroElectric-List: ATC slo blo?
--> <tim2542@sbcglobal.net>
Ummm, check me but I'm pretty sure the power to the PMAG is protected with a
pull-able breaker or other, but it does not run power thru the switch. Also,
you want the power from the switched side of the master relay not the always
hot bus as you indicated because the PMAG draws power even when switched off
via the P lead.
The switch operates just as a P lead to kill the ignition, but it does not
interrupt power to the unit.
A pull-able breaker is desired so you can check the internal alternator
function as part of your run up. Pull the breaker, kill the other ignition
and it should keep running.
One other tip, be sure to pull the breaker when using a battery charger,
PMAGs have had problems and its mentioned in the manual.
Tim
Sent from my iPad
On Mar 7, 2013, at 10:19 AM, "B Tomm" <fvalarm@rapidnet.net> wrote:
> --> <fvalarm@rapidnet.net>
>
> Anyway...
>
> I currently have 5-amp fuses in the always hot battery bus feeding the
> P-mag power control switches. These switches in turn feed the power
> inputs of the P-mags.
>
> So the easy fix would be to replace the switches with a
> switch/breakers, and replace the fuses protecting the feed to the
> switch with a higher value ATC such as 10-15 amp. It's a 18 AWG wire
> all the way from the fuse block to the P-mags. Each P-mag has it's own
> independent circuit, fuse, wire and switch.
>
>
>
>
Message 24
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Subject: | Re: ATC slo blo? |
Oh I see, sounds like we're on the same page then. I thought you were leaving them
powered up from the way I read it.
Tim
Sent from my iPad
On Mar 7, 2013, at 9:12 PM, "B Tomm" <fvalarm@rapidnet.net> wrote:
>
> Thanks Tim.
>
> I understand the drawing from Emagair, and Bob's comment makes sense to me.
>
> I have a very non-standard (comprehensive) electrical system. It includes a
> very small always hot bus located 6 inches from the battery. This bus
> supplies power (via two independent circuits) to the P-mag power switches,
> not to be confused with the magneto kill switches (which are part of the
> keyed ignition). These switches must be turned on or the engine will not
> start. These switches are the ones you would turn off to test the internal
> alternators (periodically, not on each runup). They are also turned off at
> the end of flight, otherwise the battery will run down.
>
> This is how I have chosen to build my system and flows well with the rest of
> my electrical system. I know it is not for everyone, but I have like the
> way I have it.
>
> My original question came up as I was told (and I believed) that the P-mags
> should have a breaker/switch and not fuse/switch. With the very small
> current flows according to Bob M, (the Emagair spec sheet does not indicate
> current flow), and no unusually high inrush currents, fuses should be fine
> as long as I also have switches to power down the mags.
>
> On the other hand, my WigWag module (by Sound Off Signal) is solid state and
> does require a fast acting fuse to protect the controller portion, but
> that's a story for another day.
>
> Bevan
>
>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Tim
> Andres
> Sent: Thursday, March 07, 2013 8:02 PM
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: ATC slo blo?
>
> --> <tim2542@sbcglobal.net>
>
> Ummm, check me but I'm pretty sure the power to the PMAG is protected with a
> pull-able breaker or other, but it does not run power thru the switch. Also,
> you want the power from the switched side of the master relay not the always
> hot bus as you indicated because the PMAG draws power even when switched off
> via the P lead.
> The switch operates just as a P lead to kill the ignition, but it does not
> interrupt power to the unit.
> A pull-able breaker is desired so you can check the internal alternator
> function as part of your run up. Pull the breaker, kill the other ignition
> and it should keep running.
> One other tip, be sure to pull the breaker when using a battery charger,
> PMAGs have had problems and its mentioned in the manual.
> Tim
>
>
> Sent from my iPad
>
> On Mar 7, 2013, at 10:19 AM, "B Tomm" <fvalarm@rapidnet.net> wrote:
>
>> --> <fvalarm@rapidnet.net>
>>
>> Anyway...
>>
>> I currently have 5-amp fuses in the always hot battery bus feeding the
>> P-mag power control switches. These switches in turn feed the power
>> inputs of the P-mags.
>>
>> So the easy fix would be to replace the switches with a
>> switch/breakers, and replace the fuses protecting the feed to the
>> switch with a higher value ATC such as 10-15 amp. It's a 18 AWG wire
>> all the way from the fuse block to the P-mags. Each P-mag has it's own
>> independent circuit, fuse, wire and switch.
>
>
>
>
>
>
>
>
>
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