It was a dark time in the black summer of 1943. At night, hundreds of British Lancaster Bombers were savagely pounding German cities. During the day, B-17’s and B-24’s from America’s Mighty Eighth were raining thousands of tons of hard steel and incendiary death on Essen, Cologne, and Hamburg. Tens of thousands of men, women and children were incinerated in 1,000-foot-high flames and searing 1500-degree heat.
Meanwhile, the genteel socialite Peggy Guggenheim was busy as well. She had just cleared out her 31 Women exhibit of her Art from This Century Gallery just in time to make room for “Spring Salon for Young Artists”, her next act that was opening that May. Of course, she was also feverishly trying to address the nagging problem of what to do about the dreadfully barren foyer walls of her town house.
It was one of those pivotal moments when Jackson Pollock was just coming off a stint as a slightly starving artist for the WPA FAP Works Progress Administration’s Federal Art Project (, remember kiddies, lets use our acronyms). Desperate for a new gig, He joined the thousands of other starving artists and submitted his Stenographic Figure to the Spring Salon project and hoped. When Selection Day came, The Dutch art connoisseur and Peggy’s good friend Piet Mondrian strolled past the canvasses and stopped at one painting which mesmerized him. He kept staring at it as Peggy sauntered up to him.
“This young man has serious problems, and painting is one of them.” Peggy sniffed to the enamored 68-year-old bastion of modern art.
“Peggy,” he said, “I have a feeling that this may be the most exciting painting that I have seen in a long, long time, here or in Europe.”
Peggy relented and hung Jackson’s Stenographic Figure in the exhibition. By the time the exhibition ended, Guggenheim had done her due diligence with a proper background check into Jackson’s credentials. He Checked out with exemplary credentials. Indeed, He was confirmed as a genuinely starving, drunken, bipolar, moody gutter sleeping artist prone to petulant angry outbursts. The man was well qualified for an unheard of $150 a month stipend that Guggenheim paid him for the next year. “Oh, and, Daaahling, could you be a real mensch and paint something for my foyer?” she asked the overwhelmed Jackson upon delivering the news to him.
With a commission in his hot pink hand, Pollock could finally expand the business. He knocked down a wall in his crappy New York apartment, and hid the rubble before the Landlord found out. In the expanded space, he installed a 160 square foot canvas stretched across a huge frame, sat down and stared at it.
For weeks, he sat fidgeting and staring and pondering, trying to come up with something to slather on a vastness the size of a Sling Wing Skin. Peggy started getting antsy, and all Jackson could tell his friends was that he was blocked. Days and days were spent irritably dabbling along with a few strokes here, a few strokes there, and then more fidgeting and staring, a few more strokes and yet more fidgeting. Like our sling wiring effort, Jackson’s contemplating dragged on for nearly 6 months, he even missed the November solo exhibition he had at the Art of This Century Gallery. Finally, in the waning days of December of 1943, Jackson burst into wild, manic febrility, his brush slashing streaks of color on the canvas with passion. Just Like a senior year term paper, it was done in the nick of time. In just a few hours, Jackson had imparted a vision with blue, purple and yellow heads jumbled in broad dark vertical strokes. Some heads resembled horses, others resembled buffalo and antelopes that stampeded across the cloud-white canvas. Guggenheim was delighted and hung it proudly in her foyer.
“Mural”, as it was called, was the start of Jackson’s long spiraling alcohol fueled raging descent into large scale abstract modernism. He produced dozens of canvases, but in just a few short years, Pollock had upgraded to a place in the burbs with an old barn to spread the canvas across the floor to drip household paint on. No more stretched canvas painting for him: thenceforth, Pollock was known as Jack the Dripper.
By 1950, Pollock had branched out from his dribbling and tried to replicate his feats of emotional mayhem in 3-D. for 3 years he tried bending, breaking, twisting, cutting, mangling, and tormenting all sorts of things, chicken wire, plaster, bits of wood. Yet, despite his best efforts, he tragically failed to transition his feelings into controlled 3-D chaos. Sadly, adrift in the dark waves of failure, he died in a drunk driving accident, never having achieved his dream of 3-D paint splatter.
The artistic community was devastated. One of the Greatest had fallen. It would take 70 years for a medium suitable for Pollock to create his 3-D orderly chaotic vision. Were he alive today, we would find an ecstatic and giggling Pollock sitting beside a Sling fuselage, mired in Mil-2476900 wire and Garmin G3X (Axis) boxes sporadically arranged on a canvas sprawling across the floor of his barn. Amidst MIL127900 spec wire, Pollock would be joyously cutting the wire with gusto, deftly bending and swooping it around the pegs of his wiring loom, and fluidly crimping the pins on the ends, making his 3-D vision come to reality.
As for our own Pollockian descent into our Sling wiring, we wish we could say that it’s been a good time thus far. A time that the frolicking wildlife on the Mural would evoke, but alas, it is not. With our wings and fuselage sitting in our garage just chillin’, we are toiling under the glower of our Lord Slingungus effigy, learning the wisdom of farming out the wiring to a place like Midwest Panels or Steinair. It’s not the labor part that was difficult. Cutting wires and sticking those hideously teeny, little pins on the ends was child’s play compared to the time spent cranial stuffing involved with sorting out the wiring layout.
Minutes turned into hours, hours turned into days spent pouring over the manuals and schematics and anything else we could find on wiring. Slowly it dawned on us that the wiring harness is all about the different parts. The first part is the power part, We are using the Vertical Power VP-X for that. The second part or we should say bunch of parts, are all the lights, outlets, servomotors, sensors and whatnot strewn all around the airframe. Some of these are connected by wire tentacles emanating from the third bunch of parts: the G3X Line Replaceable Unit or LRU (Acronyms, kiddies!)
There are a lot of LRU’s. Heres our list:
GDU 460- This is the TV set the crew looks at when flying. They call it either a PFD or MFD so they can charge more for it. We got one, but maybe we might get one of the new Axes version.
GTN 650Xi- This does the same thing as your iPhone when it is running Foreflight, only its legal to use for doing an approach, so it costs more. A lot more.
GTR 205- Another $1,200 box you can use to yell at the idiot who cuts you off while you are on short final.
GTX 45R- MAGA definition: The mandated tool the FAA forces you to install so it can spy on you. For everyone else in the universe: another layer of safety which also serves as noise abatement, preventing the loud racket that two colliding aircraft make.
GAD 29- Behind the scenes translator that Lets the GTN 650Xi, GTR205, GTX45 have a conversation with the rest of the family.
GSU 25- Explores the outside world, the pitot tube and static ports feed air pressure into it, while electronic gyroscopes figure out which way is up.
GAD 27- The part can run the lights, the GSA 28 servos, the flaps, and do a CAT III approach (Just Kidding!) it’s kind of like what your Primary Motor Cortex, Cerebellum and Basal Ganglia do, if you are so equipped.
GEA 24- Monitors Fan health, and tells you other stuff, like how far the flaps are lowered.
GMU11- Works like a compass, it senses the Earth’s magnetic field, without using kerosene.
Gad-26 – gets rid of that pesky Pitot Ice.
GTP 59 – helps to see if you should wear shorts our a heavy coat when you arrive at your destination.
G5 – GDU Ultralite, without all that weather depiction silliness
Axis- wish we waited.
The G3X is best explained by Garmin and others, but for the sake of wiring, we boil it down to it’s a bunch of boxes each with its own special job, and they all scream at each in 4 different linguistic “protocols”. The main one is CANbus. Its a party line where all the neighbors can join in on the same conversation. For instance, the GSU 25 can tell most of the other boxes that the Sling is at 5000 feet. The PFD GDU 460 can show it on the TV screen in the altitude rectangle, and the GMC 507 will be able to issue directives to the GSA 28 servos to point the nose in the right direction, all using the same CANbus wire. Pretty nifty.
We said most of the components can do the CANbus party line thing, However, anything that talks to the outside world, meaning the GTX 45 transponder, the GTN 650Xi, and the GTR 205R share GPS and ILS data to other units in ARINC 429 and RS232. These protocols are like landlines, a bit old fashioned, but ARINC 429 has more bandwidth and is reliable enough for the GTN 650Xi to scream and be heard, while the RS232 serves as backup. the GAD 29 has to translate the AIRINC 429 into CANbus for the rest of the family.
Finally, The GTN 650Xi apparently has a lot to say to the GTR 205 and the GTX45, So much so that it needs to use Ethernet with its broadband capabilities. Sorry, its not sharing any of the bandwidth, you still need Starlink to watch the flying puppy videos Grandma sent the links to.
Finally, We have already mentioned the RS232. This is for all the stuff that is really really important, stuff like the GEA 24, the GSU 25 and GTN 650Xi. It’s in keeping with that old aviation tradition of having backups.
This is Dull. Let’s move on to the meat of the subject, building the wiring harness.
Now, Interestingly enough, we spent about as much time engaging In cranial machinations as Pollock did with his mural before taking brush to canvas. Indeed, Slingers are a wise lot and understand that harnesses are like a 3-D Jackson Pollock painting: a twisted, convoluted, and cryptic amassment of wires that is best left to the wizards at places like Midwest Panels or Steinair who have already done the brainwork. We at Connecticut Slingers have no such wisdom and had to learn this using the hard Jackson Pollock method.
First we had to study the manuals and watch some DIY Youtube. Then we had to come up with some schematics that were easier to follow than the diagrams in Chapter 24. We couldn’t draw out the schematics unless we knew what wire went to what LRU. To figure all that out we had to study the GX3 installation manual. That thing is the dreary side of dull. Its mind-numbing lack of rapturous page turning excitement is only exceeded by a Charlotte Bronte novel. It’s that bad. Fortunately, unlike Jane Eyre, it’s got pictures and tables in chapters 23, 24, and 25 shoehorned into its 1,015 pages of desert dry helpfulness.
Chapter 23 has tables that tersely tell us which pin does what, and Chapters 24, and 25 have cheat sheet style diagrams of what wire is connected where. After we spent months figuring that out, We turned to making the actual schematics. Immediately, a whole menacing tranche of dribbled Jackson Pollocks floated into our minds when we thought about the task. Smart people told us we had to do this wretched bit of homework first; there was no avoiding it.
We were desperate to get going with the wire cutting so we found a clever way to weasel out the hard work of drawing the schematics from scratch. Long story short, we found the marvelous application entitled Wiring Planner on the internet. (Thank you, Al Gore!) Wiring Planner was a genuinely sparkling delight, it came with a complete G3X wiring layout for a Glasair 2 X 2, and was already nicely done. It even included a VP-X and backup batteries! Best 20 bucks whacked to our credit card ever, We were in business. We just had to make a few adjustments.
We have thus far shoehorned in a depiction of a GHA-15 into the CANbus layout and on the power and ground drawings. This proved easier said than done. This little bit of work made it clear that Wiring Planner is at the mercy of Windows. Occasionally, it has the frustration level of riveting 5 layers of 0.063 6061 aluminum parts together. To the point, it is a bit janky, and tedious.
We won’t go too deep into how to use it here, but it comes with components and wires drawn and grouped in libraries. They have a folder for Garmin components, which are shown as block-like renderings of LRUs and lights, sockets, plugs etc. You use these components to draw out your schematic. If you want to draw in an LRU such as a GH-15, you select it from the Garmin library, drag it over to the picture, and drop it in place. Next, you do a bunch of mouse clicking, selecting from menus and typing to show pins in the component. Then you do the same for another component and finally, you install a line depicting a wire. Cables are shown as 2 or more parallel lines, and shielded cables show the standard symbol of an oval around the other cables. They are easy to draw, but we have yet to find a way to undraw them. Once a line is connected to a pin on the schematic, it can’t be unstuck and stuck on another pin. The only remedy is to delete the line and draw another, a tedious time-consuming endeavor requiring multiple steps. Then you spend the next tedious hour pacifying your raging OCD clicking and dragging the black lines and square boxes all over the page trying to create something that looks presentable to someone who can read pictures. Once the consternation dissipates, you get to do it yet again with another LRU. What fun.
This is not to criticize Wiring Planner too much, It was a noble effort by application designers laboring under the gaze of their corporate overlords. You can learn it quickly enough to use it with just a modicum of screaming at the monitor.
It took some more work to adjust wires, moving LRUs and sometimes redoing wrong connections. Eventually our schematics were at the point of being useful, and we could finally move on to building a wire layout table. We were making progress.
Pro shops like Mid-West Panels use looms which they use to bang out Sling harnesses by the dozens. These clutch toys take the guesswork out of cutting wires to the right length and hold the accumulating bunches of wires together. All the Harness Artist does is pull a wire from a reel, snake it around some pegs, cut it, and sticks the ends in clamps. With a dope loom, A harness artist can pump out a harness faster than a Suzhou embroidery artist can needle out a copy of Qi Baishi’s immortal peaches.
At this point of our wire harnessing, we can’t use a wire loom since we must Scientifically Wild-Ass Guess each wire length, a no-no in wire loom culture. Instead, we pretend with our own contraption, Sling Wire Harness Layout Table. (SWHLT)
We spent a good two hours making our SWHLT from of a 3 X 7 foot piece of 5/8 plywood laid on a 2×4 frame. We drilled 2 rows of holes for 5/8’ dowel pegs down the centre which would help hold the wires in place. To make it look even more like a loom, We mounted and labeled clamps at strategic places along the edges, one for each LRU to hold the wire ends. Now for the fun part.
There is nothing special about this part, we SWAGed a wire length, cut, labeled, placed on the SWHLT and clamped. We used the tables from chapters 24 and 25 of the installation manual to keep track, using the method the BuildFlyGo uses for his @#-10. He uses printouts from the manual as checklists, checking off the pins he is using as he fleshes out his harness. Easy enough.
We got the routine down, look at schematics, confirm on the Manual diagram, cut the wire label it. Ah yes, we will finish with our labeling scheme. For most slingers, a 4 or 5 digit number is enough, presumably it refers to some line on a table or somewhere in the schematics, neither of which would be in the hands of anyone servicing the equipment. So we came out with our own labeling plane. Here’s an example:
W27 O46 B8 P1001 GTN650 W48 O34 B47 P4602 GDU460.
In case you couldn’t be bothered figuring it out, here is how it works: the W, O and B are the initials for the wire colors, and the numbers beside them are the pins where the wire goes. The last group of letters and numbers are the LRUs. This is a long label, but in the grand scheme of things the labeling cartridges for our Brady M511 label makers are cheap…enough.
Finally. We apologize for this long period since our last entry. We spent a lot of time working out the wiring and doing the electrical stuff turned out to be more about thinking, pondering and staring at a computer screen than about accomplishing anything of substance. Nevertheless, progress is underway, and we hope to be picking up the pace going forward.
Stay Tuned.