Today's Message Index:
----------------------
1. 05:26 AM - AC 43.13-1B circuit protection recommendations (Tailwind1)
2. 05:55 AM - Re: antenna analyzer? Antennas (hairy_kiwi)
3. 07:13 AM - Re: AC 43.13-1B circuit protection recommendations (johnbright)
4. 09:34 AM - Re: Breaker then pump failure (Robert L. Nuckolls, III)
5. 09:54 AM - Re: AC 43.13-1B circuit protection recommendations (Robert L. Nuckolls, III)
6. 10:05 AM - Re: Breaker then pump failure (Charlie England)
7. 12:13 PM - Re: Breaker then pump failure (Robert L. Nuckolls, III)
8. 12:46 PM - Re: Re: antenna analyzer? Antennas (Robert L. Nuckolls, III)
9. 01:31 PM - Some new battery chemistries on the horizon? (Robert L. Nuckolls, III)
10. 04:58 PM - Re: Breaker then pump failure (Kelly McMullen)
11. 10:18 PM - Re: Breaker then pump failure (David Saylor)
12. 10:53 PM - Re: Breaker then pump failure (David Saylor)
Message 1
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| Subject: | AC 43.13-1B circuit protection recommendations |
Looking at table 11-3 in the 43.13, the table shows lower amperage recommendations
for fuses versus circuit breakers in many cases. Bob has shown us how much
quicker a fuse operates versus a CB so logic seems to suggest a higher fuse rating
versus a CB. What am I missing?
Thanks!
--------
Flying Sonerai II with A80 Continental. Wittman W10 Tailwind under construction,
O360, dual LSE electronic ignition, airframe complete and covered, engine hung,
cowl built. Working on electrical, instrumentation, and other details.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=498695#498695
Message 2
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| Subject: | Re: antenna analyzer? Antennas |
Hi Group,
Long time lurker here. Hopefully, as the OP made the title rather broadband ;)
a general discussion on aviation / aircraft antenna design and using antenna
analyzers for verifying experiments is welcome here. Otherwise, apologies for
further dragging the discussion away from the otherwise fascinating DDRR antenna
design...
I recently bought a Rig Expert AA 230 ZOOM analyzer, primarily for helping to diagnose
faults in antenna coax while doing the odd bit of experimental aircraft
rewiring. Its been a great tool for quickly and easily finding poorly made BNC
terminations for example (wire disconnected from center pin in a poorly made,
screw-together style BNC connector) and checking SWR in a comm antenna epoxied
into a composite aircraft is still acceptable years after construction.
As for using an analyzer for antenna design, the interesting, very detailed paper
Eric posted a link to, titled 'Airborne VHF Printed Monopole Antenna for Platform
Constrained Applications' looks like it could be a fun design to experiment
with - possibly for installing inside the fin of the Kitfox I'm going to
be building - especially as the ground plane is incorporated in the same plane
as the antenna.
I have a basic understanding of antenna design, but its very basic - and with a
few antenna issues and projects on the go, I'd be very interested in furthering
my knowledge and doing some experimenting with the aid of the analyzer. What
would be useful are some links to modern literature on aviation/aircraft antenna
design - many thanks Eric for your post!
I had a browse through the ARRL Antenna Book which is a great tome of info, however
the vast majority of that material is aimed at ground station antennas. So
I'm still unclear on such things as by how much proximity to The Earth the SWR
of an aircraft (comm) antennas is affected. Maybe a flight vs ground test comparison
using an analyzer might be interesting to conduct, even if it proves
'no significant difference', particularly for 1/2 wave dipoles fitted internally
to composite aircraft.
I've found some other recently published and interesting material with test results
on (ground based) 2m 1/2 wave dipole designs that might be worth experimenting
/ adapting for aircraft use, but will save that for another post if there's
interest.
Cheers,
Jim
Hamish 'Jim' Mead
Ledbury, UK
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=498696#498696
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| Subject: | Re: AC 43.13-1B circuit protection recommendations |
Here's an image of Table 11-3.
--------
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
https://drive.google.com/drive/folders/1u6GeZo6pmBWsKykLNVQMvu4o1VEVyP4K
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=498698#498698
Attachments:
http://forums.matronics.com//files/ac_4313_1b_table_11_3_301.jpg
Message 4
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| Subject: | Re: Breaker then pump failure |
At 10:14 PM 10/7/2020, you wrote:
I just had the Tyco switch/breaker for my boost pump fail. It made a
bad smell, then became intermittent, then failed completely in the
span of a few minutes. I replaced it with the same make and model.
Do you still have the carcass? I'd like to have
it . . .
2.5 flight hours later my boost pump failed. The new breaker never
tripped. The pump just stopped running. The pump circuit has no
resistance and I get full bus voltage at the pump, even with the pump
still connected. So it's open inside. The new switch is working fine.
Agreed
The pump is from Airflow Performance. They're common in RVs. The
pump and the switch had almost 2000 airframe hours since
installed. I use it for take-off and landing, so the powered time is
a fraction of the total time.
I think that pump has a PM motor with brushes.
It's not uncommon for such devices to suffer
as much degradation from idle time as from
service life. In any case, I'm betting that
the pathway through the armature is open for
reasons we do not yet know. Does the pump
have a 'cure' value? If not, I'd be pleased
to do a autopsy on it too.
The airplane had been sitting for almost a year, then flown about 15
hours in the last two weeks.
Does anyone have an understanding of any relationship between these
two failures? They seem too similar to be completely unrelated. My
guess is that a faulty pump somehow overloaded a faulty breaker, then
failed completely. I couldn't say that I noticed any particular fuel
pressure issues before the failure. Everything was in the green.
Thoughts?
I suspect they are not related. In theory, you
can't damage a breaker by 'overloading' it . . . after
all, its core mission in life is to protect from
the consequences of such conditions including self
destruction. Getting a look at the carcasses might
offer more clues.
Bob . . .
Message 5
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| Subject: | Re: AC 43.13-1B circuit protection recommendations |
At 07:25 AM 10/8/2020, you wrote:
>
>Looking at table 11-3 in the 43.13, the table shows lower amperage
>recommendations for fuses versus circuit breakers in many cases. Bob
>has shown us how much quicker a fuse operates versus a CB so logic
>seems to suggest a higher fuse rating versus a CB. What am I missing?
I haven't a clue. I questioned this in the critical review
we submitted through EAA many moons ago but the item
was never modified or explained. If I were to WAG this
one, the writer may have been comparing performance
of fuses vs. magnetic breakers. In this case the breakers
are faster than fuses . . . but TERRIBLE choices for
general use in light aircraft power distribution.
If one simply compares the fusing dynamics of the
fuses vs. thermal breakers, the AC43-13 suggestion
doesn't make sense at all.
Actually, there's no reason to up-size the rating
of protection based on the technology. Breaker and
wire ratings are based on effects of the wire's
natural self-heating and is concerned only with
the wire's INSULATION. Long term heating effects
are a function of NORMAL current flows, voltage
drops in wire and temperature of the environment
which includes both the airframe and adjacent
wires in bundles.
That's a real snarl of snakes to unwind for
all but design goals of the most pedantic
of program managers. For our purposes, the
rule of thumb is, "if in doubt, up-size the
wire and protection to the next step."
Moving up can only reduce effects of NORMAL
heating. Consider that 99% of all
breaker/fuse events are caused by ABNORMAL
current well above the NORMAL . . . like
hard shorts or catastrophic failures in
appliances. We are virtually never victims
of a failed insulation condition . . .
The short answer is: Your common sense questioning
of the AC43-13 assertion is valid. Ignoring
it based on your own study of PROPERTIES
OF MATERIALS is not a risky thing to do.
Bob . . .
Message 6
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| Subject: | Re: Breaker then pump failure |
On Thu, Oct 8, 2020 at 11:42 AM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 10:14 PM 10/7/2020, you wrote:
> snipped .
>
> 2.5 flight hours later my boost pump failed. The new breaker never
> tripped. The pump just stopped running. The pump circuit has no
> resistance and I get full bus voltage at the pump, even with the pump still
> connected. So it's open inside. The new switch is working fine.
>
> Agreed
>
>
> The pump is from Airflow Performance. They're common in RVs. The pump
> and the switch had almost 2000 airframe hours since installed. I use it
> for take-off and landing, so the powered time is a fraction of the total
> time.
>
> I think that pump has a PM motor with brushes.
> It's not uncommon for such devices to suffer
> as much degradation from idle time as from
> service life. In any case, I'm betting that
> the pathway through the armature is open for
> reasons we do not yet know. Does the pump
> have a 'cure' value? If not, I'd be pleased
> to do a autopsy on it too.
>
> The airplane had been sitting for almost a year, then flown about 15 hours
> in the last two weeks.
>
>
> Does anyone have an understanding of any relationship between these two
> failures? They seem too similar to be completely unrelated. My guess is
> that a faulty pump somehow overloaded a faulty breaker, then failed
> completely. I couldn't say that I noticed any particular fuel pressure
> issues before the failure. Everything was in the green.
>
> Thoughts?
>
> I suspect they are not related. In theory, you
> can't damage a breaker by 'overloading' it . . . after
> all, its core mission in life is to protect from
> the consequences of such conditions including self
> destruction. Getting a look at the carcasses might
> offer more clues.
>
>
> Bob . . .
>
The core pump in the AFP pumps I'm familiar with are Airtex brand in-line
fuel injection pumps, available online for between $60 & $100. Like this?
https://www.amazon.com/Airtex-E2000-Electric-Fuel-Pump/dp/B000C1KHJG/ref=sr_1_7?dchild=1&keywords=airtex+fep2000+fuel+pump&qid=1602176199&sr=8-7
Either E2000 or FEP2000. Note that the hose barb shown on one end screws
off, allowing various other adapters.
If the OP wishes, I can measure my FEP2000 to verify dimensions.
Charlie
Message 7
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| Subject: | Re: Breaker then pump failure |
>
>The core pump in the AFP pumps I'm familiar with
>are Airtex brand in-line fuel injection pumps,
>available online for between $60 & $100. Like this?
><https://www.amazon.com/Airtex-E2000-Electric-Fuel-Pump/dp/B000C1KHJG/ref
=sr_1_7?dchild=1&keywords=airtex+fep2000+fuel+pump&qid=1602176199&sr
=8-7>https://www.amazon.com/Airtex-E2000-Electric-Fuel-Pump/dp/B000C1KHJG/
ref=sr_1_7?dchild=1&keywords=airtex+fep2000+fuel+pump&qid=1602176199
&sr=8-7
>Either E2000 or FEP2000. Note that the hose barb
>shown on one end screws off, allowing various other adapters.
>If the OP wishes, I can measure my FEP2000=C2 to verify dimensions.=C2
>
>Charlie
Interesting. The specs speak to commutators and
brushes. I also deduce that this style of pump
is used on a lot of medium pressure EFI systems.
It will be interesting to see if we can open
Dave's dead one for a closer looksee.
Bob . . .
Message 8
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| Subject: | Re: antenna analyzer? Antennas |
At 07:53 AM 10/8/2020, you wrote:
Hi Group,
Long time lurker here. Hopefully, as the OP made the
title rather broadband ;) a general discussion on
aviation / aircraft antenna design and using antenna
analyzers for verifying experiments is welcome here.
Otherwise, apologies for further dragging the discussion
away from the otherwise fascinating DDRR antenna design...
I think we're done with the DDRR for now.
It seems unlikely that a satisfactory fabrication
technique for increasing bandwidth will be
forthcoming.
The antenna gurus all seem to agree that the
perfect triad of size, efficency and bandwidth
is like finding a way to to resolve cube roots
with a pencil/paper. Unfortunately for the DDRR, the
primary driver (size) put the kibosh on at least
one of the other two, mainly bandwidth.
I recently bought a Rig Expert AA 230 ZOOM analyzer,
<snip>
I've seen those tools on the web . . . they seem
widely utilized with satisfaction.
As for using an analyzer for antenna design, the interesting, very
detailed paper Eric posted a link to, titled 'Airborne VHF Printed
Monopole Antenna for Platform Constrained Applications' looks like it
could be a fun design to experiment with - possibly for installing
inside the fin of the Kitfox I'm going to be building - especially as
the ground plane is incorporated in the same plane as the antenna.
On page 2 we find this statement, "The major constraint
in designing an airborne printed monopole antenna
in VHF/UHF band is achieving compactness and wide
bandwidth simultaneously, along with sufficient gain."
This assertion pays homage to the SEB triad with
the operative phrase being "sufficient gain".
Figure 6 shows that a very satisfactory bandwidth
was achieved while Figure 7 shows the sacrifices in
efficiency wherein the two test conditions demonstrate
losses of 6 to 15 dB over the bandwidth of interest.
That's 1/4 to 1/32 of the radiated energy offered
by the reference antenna. Sufficient? Maybe. Recall
that all VHF comm is line of sight . . . you don't
talk past the horizon and in any case, it's almost
never necessary to have conversation beyond 50
miles or so. So maybe, just maybe an antenna with
that efficiency profile would provide satisfactory
communications for some if not all builders.
The proof is in the pudding (I prefer vanilla-tapicoa
myself).
I had a browse through the ARRL Antenna Book which is a great tome of
info, however the vast majority of that material is aimed at ground
station antennas. So I'm still unclear on such things as by how much
proximity to The Earth the SWR of an aircraft (comm) antennas is affected.
It's not . . . but proximity to conducting aircraft
structure (artificial ground) is. So ground vs.
airborne testing is probably not useful.
The flight test of intense interest would be with
perhaps a software driven receiver (SDR) on board
where you would fly 360s out 40 miles or so from a handy
ground station and plot comparative azimuth measurements of your
test antenna with respect to a more conventional vhf comm
whip. We used to do a good bit of this type testing
at Hawer-Beech . . . which requires another previously
expensive but now not so much spectrum analyzer/receiver
with signal strength display.
I've found some other recently published and interesting material
with test results on (ground based) 2m 1/2 wave dipole designs that
might be worth experimenting / adapting for aircraft use, but will
save that for another post if there's interest.
Let's look at them . . .
Bob . . .
Message 9
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| Subject: | Some new battery chemistries on the horizon? |
While lithium products are the fair-haired
children in the portable energy storage
sandbox, there's a couple of interesting
technologies being spun-up in the EV
world:
https://tinyurl.com/yy8cqwbe
https://tinyurl.com/y2ptgrjz
These MIGHT find application in aviation
and consumer products with some dispatch.
Contemporary EV batteries evolved up
from the smaller, less energetic
consumer products. These new kids
on the block will enjoy immediate
success and large scale production in
a particularly battery-intensive market:
EVs.
It seems likely that they could 'spill
out' into the consumer markets quickly.
It's intuitively easier to evolve-
down a product that's already enjoying
high volume successes.
We'll have to wait and see . . .
Bob . . .
Message 10
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| Subject: | Re: Breaker then pump failure |
I believe Airflow Performance with do a rebuild at reasonable price.
Might not get the diagnosis desired, but could be cheaper than alternatives.
On 10/8/2020 12:08 PM, Robert L. Nuckolls, III wrote:
>>
>> The core pump in the AFP pumps I'm familiar with are Airtex brand
>> in-line fuel injection pumps, available online for between $60 & $100.
>> Like this?
>> https://www.amazon.com/Airtex-E2000-Electric-Fuel-Pump/dp/B000C1KHJG/ref=sr_1_7?dchild=1&keywords=airtex+fep2000+fuel+pump&qid=1602176199&sr=8-7
>>
>> Either E2000 or FEP2000. Note that the hose barb shown on one end
>> screws off, allowing various other adapters.
>> If the OP wishes, I can measure my FEP2000 to verify dimensions.
>>
>> Charlie
>
> Interesting. The specs speak to commutators and
> brushes. I also deduce that this style of pump
> is used on a lot of medium pressure EFI systems.
>
> It will be interesting to see if we can open
> Dave's dead one for a closer looksee.
>
>
> Bob . . .
>
Message 11
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| Subject: | Re: Breaker then pump failure |
Charlie wrote:
> The core pump in the AFP pumps I'm familiar with are Airtex brand in-line
> fuel injection pumps, available online for between $60 & $100. Like this?
>
> https://www.amazon.com/Airtex-E2000-Electric-Fuel-Pump/dp/B000C1KHJG/ref=sr_1_7?dchild=1&keywords=airtex+fep2000+fuel+pump&qid=1602176199&sr=8-7
> Either E2000 or FEP2000. Note that the hose barb shown on one end screws
> off, allowing various other adapters.
> If the OP wishes, I can measure my FEP2000 to verify dimensions.
>
> Charlie
>
Between Amazon and the Airtex web site, my pump seems most like an E8445.
There are a lot of models and I haven't ID'd it exactly. The E2000 looks
the same but it puts out almost three times the pressure that I see.
I sent my pump assy to AFP where they replaced the pump for a little more
than the Amazon price. They did a great job, shipping back the repaired
assembly within hours of receiving it.
Bob, if I get the old pump back, I'll send it to you along with the breaker.
BTW, I just became aware of an AD from 2008 to replace this type of CB
switch in Beechcraft products.
--Dave
Message 12
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| Subject: | Re: Breaker then pump failure |
Bob wrote:
> Do you still have the carcass? I'd like to have
> it . . .
>
Here's a picture for now. I broke in before I sent my initial message.
Charred remains to follow.
I'm almost certain that the braid broke when I opened it.
The little barbequed U spring is missing most of its legs. I wonder if one
broke off and shorted something to start the failure.
The switch had lost it's "snap" after it quit.
Here's a picture from a Beech website.
<https://www.csobeech.com/breaker-switches.html> These are serviceable and
very similar to what I have.
[image: image.png]
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