Today's Message Index:
----------------------
1. 05:33 AM - EarthX on Firewall (Neal George)
2. 06:06 AM - Re: Archer style wingtip antenna fabrication questions (Charlie England)
3. 06:14 AM - Re: EarthX on Firewall (Rob Turk)
4. 09:01 AM - Re: EarthX on Firewall (Ernest Christley)
5. 09:27 AM - Re: EarthX on Firewall (Rob Turk)
6. 09:30 AM - Re: Archer style wingtip antenna fabrication questions (Robert L. Nuckolls, III)
7. 09:34 AM - Re: EarthX on Firewall (Neal George)
8. 09:51 AM - Re: EarthX on Firewall (Ernest Christley)
9. 10:02 AM - Re: Archer style wingtip antenna fabrication questions (johnbright)
10. 11:05 AM - Re: EarthX on Firewall (Robert L. Nuckolls, III)
11. 11:12 AM - Re: EarthX on Firewall (Robert L. Nuckolls, III)
12. 11:18 AM - Vector Network Analyzer (Robert L. Nuckolls, III)
13. 12:58 PM - Re: EarthX on Firewall (Ernest Christley)
14. 08:09 PM - Re: EarthX on Firewall (Robert L. Nuckolls, III)
Message 1
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| Subject: | EarthX on Firewall |
Bob -
For a Rotax-powered KitFox:
Any heat-related concerns for putting an EarthX ETX680C on the firewall?
Neal
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=502544#502544
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| Subject: | Re: Archer style wingtip antenna fabrication questions |
On Tue, Jun 22, 2021 at 10:52 PM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 12:03 PM 6/22/2021, you wrote:
>
> I have an Archer wingtip comm=C3=82 antenna I intend to install in one w
ingtip
> (can always add a 1/4 wave whip if needed), and I'm thinking about buildi
ng
> the nav version detailed in Bob's 'Antennas & Feedlines chapter for the
> other wingtip (figure 13-12 in my document).
>
> How critical is the material for the .032" x .8" x 3.25" bakelite
> insulator that forms what I'm guessing is a matching capacitor? Does the
> bakelite participate in any way in operation, or is it simply a way to ge
t
> a fixed air gap?
>
> Bakelite in that 'thinness' doesn't seem to be available without paying
> more for shipping than the 3-postage-stamp size needed would cost. What
> about=C3=82 substituting something like the thin HDPE cutting board stock
,
> available at discount stores? Two layers would be about .034" thick.=C3
=82
>
>
> It IS critical . . . yes it forms the dielectric
> for a capacitor used to series resonate the feeder
> strut.
>
> Bob must have conducted experiments to optimize
> the characteristics of that capacitor with respect
> to the matching strut for optimal mid-band impedance
> match.
>
> If it were my project, I'd use ANY available dielectric
> material and conduct experiments over a ground plane
> on the table to achieve (1) antenna resonance and
> (2) best match to the feed line.
>
> When I was a kid, a 'gamma match' was commonly
> used to bring a feed line and antenna radiator
> into functional harmony. The attached figure
> illustrates an adjustable feeder strut paired
> with a variable capacitor to feed a grounded
> quarter-wave antenna.
>
> My 10M, 2-element beam had such a feature that
> was tuned with the aid of an SWR bridge. Today,
> a vector network analyzer is the instrument
> of choice and can cost less than a good SWR
> meter.
>
> After getting close on the bench, you can
> confirm on the airplane to see if 'tweeking'
> is called for. I've had readers assemble the
> Archer wing tip antennas per drawings but found
> it useful to trim dimensions per measured results.
>
>
> Bob . . .
>
If any dielectric is worth a shot, I think I'll try my flexible cutting
board idea for a start. I've got a pack of them on the shelf, left over
from another project (bearing surface for the round top tube of an aluminum
hangar door). Package says 43% HDPE/57% EVA, and it's ~0.017" thick, so 2
layers will be pretty close in thickness, at least. How critical is tuning,
for a receive-only Nav antenna? I do have a NanoVNA; I just need to learn
how to use it. ;-)
Thanks for the offer on the dielectric, but let me give the cutting board a
shot first.
BTW, since this is a Nav antenna and can lie flat on the bottom of the
wingtip, I'm thinking I may try aluminum flashing (~0.008"), and slightly
'break' the edges to stiffen it. Any issues with that, if width/length
dimensions are maintained?
Charlie
Message 3
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| Subject: | Re: EarthX on Firewall |
Neal,
Might be best to follow the manufacturer's recommendations:
https://earthxbatteries.com/engine-compartment-battery-installations
Rob
On 6/23/2021 2:32 PM, Neal George wrote:
>
> Bob -
> For a Rotax-powered KitFox:
> Any heat-related concerns for putting an EarthX ETX680C on the firewall?
>
> Neal
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=502544#502544
>
>
Message 4
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| Subject: | Re: EarthX on Firewall |
Huh?=C2- Those recommendations don't make sense to me.
The first chart seems to indicate that the box will hold the heat off for 3
0 min in a static situation.=C2- That makes sense, because the engine is
cooling down during that 30 min and the delay will keep the battery from hi
tting that red line.
If taken at face value, the second seems to say that you're limited to 90 m
inutes of flight time.=C2- After that, you're killing your battery.
Are they seriously saying this?=C2- And what happens when you park after
a 2hr flight, and the battery is already heat soaked?
On Wednesday, June 23, 2021, 09:15:22 AM EDT, Rob Turk <matronics@rtist
.nl> wrote:
Neal,
Might be best to follow the manufacturer's recommendations:
https://earthxbatteries.com/engine-compartment-battery-installations
Rob
On 6/23/2021 2:32 PM, Neal George wrote:
matronics.com>
>
> Bob -
> For a Rotax-powered KitFox:
> Any heat-related concerns for putting an EarthX ETX680C on the firewall?
>
> Neal
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=502544#502544
>
>
-
S -
WIKI -
-
=C2- =C2- =C2- =C2- =C2- -Matt Dralle, List Admin.
Message 5
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| Subject: | Re: EarthX on Firewall |
If it's any indication, I'm running an AeroAkku LFP450D (450A CCA, 7Ah)
next to my Jabiru 3300 shoe-horned in a small cowl. The battery is
mounted low on the firewall, so heat trapped under the cowl when parked
doesn't affect it as much as one mounted high up. But still, everything
hot is nearby. I do not have a heat shield or box
I've ran my first battery from 2013 to last year. Then replaced it for
peace of mind. Measured endurance and CCA of the 7+ battery, and it was
as good as new (440CCA, 7Ah). On my second battery, keeping the first
one around for experiments and helping out others with flat batteries
On 6/23/2021 6:00 PM, Ernest Christley wrote:
> Huh? Those recommendations don't make sense to me.
>
> The first chart seems to indicate that the box will hold the heat off
> for 30 min in a static situation. That makes sense, because the
> engine is cooling down during that 30 min and the delay will keep the
> battery from hitting that red line.
>
> If taken at face value, the second seems to say that you're limited to
> 90 minutes of flight time. After that, you're killing your battery.
>
> Are they seriously saying this? And what happens when you park after
> a 2hr flight, and the battery is already heat soaked?
>
>
Message 6
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| Subject: | Re: Archer style wingtip antenna fabrication questions |
>
>If any dielectric is worth a shot, I think I'll try my flexible
>cutting board idea for a start. I've got a pack of them on the
>shelf, left over from another project (bearing surface for the round
>top tube of an aluminum hangar door). Package says 43% HDPE/57% EVA,
>and it's ~0.017" thick, so 2 layers will be pretty close in
>thickness, at least. How critical is tuning, for a receive-only Nav
>antenna? I do have a NanoVNA; I just need to learn how to use it. ;-)
The reason that any dielectric can be considered is
based on the physics of capacitors. The value of a
capacitor is proportional to area of the 'plates',
space between the plates, and dielectric constant
of the material.
Here's a comprehensive tutorial on the topic:
http://www.phys.uri.edu/gerhard/PHY204/slides8-phy204.pdf
In cases like this, one can estimate the value
of any particular capacitor fabrication with
the goal of duplicating Bob Archer's design
goals. It would be REALLY nice if we had
an Archer Original to measure the value of
his productions.
>Thanks for the offer on the dielectric, but let me give the cutting
>board a shot first.
No problem. I thought about the cutting sheets
too but wondered if their flexibility might
compromise the mechanical integrity of Bob's
original design goal. But we're in experimental
waters here.
>BTW, since this is a Nav antenna and can lie flat on the bottom of
>the wingtip,
>I'm thinking I may try aluminum flashing (~0.008"), and slightly 'break' the
>edges to stiffen it. Any issues with that, if width/length
>dimensions are maintained?
Skin effects for current flow due to operating
frequency tell us that thickness of a conductor
has no practical influence on performance. It's
surface area and then only to a depth of .001"
or so. The primary concern for materials selection
are conductivity (aluminum and copper are good)
and mechanical robustness suited to the environment.
Bob's antennas were no more 'robust' than needed to
avoid falling apart or breaking.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 7
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| Subject: | Re: EarthX on Firewall |
Ernest -
That=99s the way I read it.
Doesn=99t address airflow under the cowl during flight, nor does
it speak to natural convective cooling after shutdown.
KitFox, on the other hand, recommends firewall-forward mounting in a
simple tray, no box
Neal
On Jun 23, 2021, at 11:00 AM, Ernest Christley <echristley@att.net>
wrote:
Huh? Those recommendations don't make sense to me.
The first chart seems to indicate that the box will hold the heat off
for 30 min in a static situation. That makes sense, because the engine
is cooling down during that 30 min and the delay will keep the battery
from hitting that red line.
If taken at face value, the second seems to say that you're limited to
90 minutes of flight time. After that, you're killing your battery.
Are they seriously saying this? And what happens when you park after a
2hr flight, and the battery is already heat soaked?
On Wednesday, June 23, 2021, 09:15:22 AM EDT, Rob Turk
<matronics@rtist.nl> wrote:
<mailto:matronics@rtist.nl>>
Neal,
Might be best to follow the manufacturer's recommendations:
https://earthxbatteries.com/engine-compartment-battery-installations
<https://earthxbatteries.com/engine-compartment-battery-installations>
Rob
On 6/23/2021 2:32 PM, Neal George wrote:
<neal@appaero.com.matronics.com <mailto:neal@appaero.com.matronics.com>>
>
> Bob -
> For a Rotax-powered KitFox:
> Any heat-related concerns for putting an EarthX ETX680C on the
firewall?
>
> Neal
Message 8
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| Subject: | Re: EarthX on Firewall |
I had my first LiFePo strapped to the firewall with no protection.
Heat from the exhaust pipe destroyed it.=C2- You could see where it swell
ed up on the bottom just above the pipe.=C2- Built a heat shield shelf to
sit it on with some intervening insulation tape, and it is doing fine so f
ar.
Heat in the engine compartment is a lot like magnets in the cockpit.=C2-
Inches make a HUGE difference.
On Wednesday, June 23, 2021, 12:35:19 PM EDT, Neal George <neal.george@
gmail.com> wrote:
Ernest -=C2-That=99s the way I read it.Doesn=99t address air
flow under the cowl during flight, nor does it speak to natural convective
cooling after shutdown.
KitFox, on the other hand, recommends firewall-forward mounting in a simple
tray, no box=C2-
Neal=C2-
On Jun 23, 2021, at 11:00 AM, Ernest Christley <echristley@att.net> wrote:
Huh?=C2- Those recommendations don't make sense to me.
The first chart seems to indicate that the box will hold the heat off for 3
0 min in a static situation.=C2- That makes sense, because the engine is
cooling down during that 30 min and the delay will keep the battery from hi
tting that red line.
If taken at face value, the second seems to say that you're limited to 90 m
inutes of flight time.=C2- After that, you're killing your battery.
Are they seriously saying this?=C2- And what happens when you park after
a 2hr flight, and the battery is already heat soaked?
On Wednesday, June 23, 2021, 09:15:22 AM EDT, Rob Turk <matronics@rtist
.nl> wrote:
Neal,
Might be best to follow the manufacturer's recommendations:
https://earthxbatteries.com/engine-compartment-battery-installations
Rob
On 6/23/2021 2:32 PM, Neal George wrote:
matronics.com>
>
> Bob -
> For a Rotax-powered KitFox:
> Any heat-related concerns for putting an EarthX ETX680C on the firewall?
>
> Neal
Message 9
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| Subject: | Re: Archer style wingtip antenna fabrication questions |
Ceengland wrote:
> ... I do have a NanoVNA; I just need to learn how to use it. ;-)
>
> Charlie
MegawattKS is a retired electrical engineering professor from Kansas State University
in Manhattan, KS. He has YouTube videos about the NanaVNA.
https://www.youtube.com/user/MegawattKS
--------
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://docs.google.com/document/d/1YOtPiA3AdUsQEYR4nodBESNAo21rxdnx4pFs7VxXfuI/edit?usp=sharing
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=502559#502559
Message 10
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| Subject: | Re: EarthX on Firewall |
At 11:00 AM 6/23/2021, you wrote:
>Huh? Those recommendations don't make sense to me.
>
>The first chart seems to indicate that the box will hold the heat
>off for 30 min in a static situation. That makes sense, because the
>engine is cooling down during that 30 min and the delay will keep
>the battery from hitting that red line.
>
>If taken at face value, the second seems to say that you're limited
>to 90 minutes of flight time. After that, you're killing your battery.
>
>Are they seriously saying this? And what happens when you park
>after a 2hr flight, and the battery is already heat soaked?
I think the experimental data explores a hypothetical
heat transfer from an exhaust pipe to the battery.
The environmental chamber is a constant source
of heating which does not exist under the cowl.
Exhaust plumbing is a source of RADIANT heat that's easy to
avoid. I don't recall any GA battery installation
on a firewall that was at-risk for radiant
heating.
Tests we conducted on firewall mounting locations
at Cessna waaayyy back when demonstrated that
the highest temperatures experienced on the
firewall were AFTER engine shutdown with the
aircraft sitting in a zero-wind condition. Even
then, transient temperatures were not real exciting . . .
about 160F as I recall for minutes.
Turbo engines were hotter after shutdown
due to larger mass of really warm metal positioned
in the lower regions of the cowl where convection flow
would take the BTUs upward. It was not uncommon
for pilot's to open the oil filler access
door to allow heat to escape while waiting
for the fuel truck to do it's thing.
For the vast majority of our projects, any
battery should live well sitting out in the
open on a firewall mounted battery tray.
It doesn't get all that hot there in
flight and only for short periods of time
in various non-flight conditions.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 11
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| Subject: | Re: EarthX on Firewall |
At 11:49 AM 6/23/2021, you wrote:
>I had my first LiFePo strapped to the firewall with no protection.
>
>Heat from the exhaust pipe destroyed it. You could see where it
>swelled up on the bottom just above the pipe. Built a heat shield
>shelf to sit it on with some intervening insulation tape, and it is
>doing fine so far.
>
>Heat in the engine compartment is a lot like magnets in the
>cockpit. Inches make a HUGE difference.
Yes . . . if you put a hotdog on a spit over a fire,
it's reasonable to expect it to get toasted. This
builder might have avoided the experience by taking
advantage of the various forums available.
General aviation is over a century old . . . designers
have learned a great deal about what works . . . and
what doesn't . . . and why.
Heat shield? Yup . . . who wuda thunk it? When
in doubt, research the history.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 12
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| Subject: | Vector Network Analyzer |
>MegawattKS is a retired electrical engineering professor from Kansas
>State University in Manhattan, KS. He has YouTube videos about the NanaVNA.
>
>https://www.youtube.com/user/MegawattKS
haven't watched all of these but what I've
seen are well done!
A builder's first tool needs to be a multi-meter . . .
it may well be that the second needs to be a VNA.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 13
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| Subject: | Re: EarthX on Firewall |
=C2-=C2- Heat shield? Yup . . . who wuda thunk it? When
=C2-=C2- in doubt, research the history.
=C2- Bob . . .
=C2- =C2-
When in doubt?=C2- The true enemy is lack of doubt.=C2- :-)
Message 14
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| Subject: | Re: EarthX on Firewall |
>When in doubt? The true enemy is lack of doubt. :-)
Yeeaaahh . . . sort of . . . all successful
inventions have foundations in knowledge:
Properties of materials, management of energy and
refinement of process.
Any recipe for success features a useful
mix of those qualities that can be shared
with confidence of achieving the same results.
Hence I suggest that the greatest risk to
success arises out of ignorance. The
thinking craftsman should have doubts
when the task at hand is not paired with
a recipe for success.
This is why networking . . . whether
through formalized venues such as forums,
special interest groups, etc have become
the go-to sources for the evolution, proofing
and sharing of recipes.
The more knowledge is given away, the
greater its worth. The worth of an idea
never shared cannot be measured.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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