---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 06/23/21: 14 ---------------------------------------------------------- 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 _____________________________________ Time: 05:33:12 AM PST US Subject: AeroElectric-List: EarthX on Firewall From: "Neal George" 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 2 _____________________________________ Time: 06:06:21 AM PST US From: Charlie England Subject: Re: AeroElectric-List: 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 _____________________________________ Time: 06:14:30 AM PST US Subject: Re: AeroElectric-List: EarthX on Firewall From: Rob Turk 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 _____________________________________ Time: 09:01:33 AM PST US From: Ernest Christley Subject: Re: AeroElectric-List: 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 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 _____________________________________ Time: 09:27:26 AM PST US Subject: Re: AeroElectric-List: EarthX on Firewall From: Rob Turk 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 _____________________________________ Time: 09:30:59 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: 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 _____________________________________ Time: 09:34:25 AM PST US From: Neal George Subject: Re: AeroElectric-List: 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 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 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: > > > Bob - > For a Rotax-powered KitFox: > Any heat-related concerns for putting an EarthX ETX680C on the firewall? > > Neal ________________________________ Message 8 _____________________________________ Time: 09:51:49 AM PST US From: Ernest Christley Subject: Re: AeroElectric-List: 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 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 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 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 _____________________________________ Time: 10:02:28 AM PST US Subject: AeroElectric-List: Re: Archer style wingtip antenna fabrication questions From: "johnbright" 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 ____________________________________ Time: 11:05:34 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: 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 ____________________________________ Time: 11:12:00 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: 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 ____________________________________ Time: 11:18:50 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: 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 ____________________________________ Time: 12:58:13 PM PST US From: Ernest Christley Subject: Re: AeroElectric-List: 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 ____________________________________ Time: 08:09:44 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: 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?" ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.