What we used:
Into the Hills!
If there is one thing to be said about building a Sling via the Artisanal Ikea Flat Pack (AIFP) route, it is that, like all great things, it begins with an end, or in Sling parlance, an empennage. It is in concept, like the first thing you see during a trip through the Lugdunum while on your way to the theatre to cap off a day in Lyons.
On the day of his visit to Lugdunum, our fact-finding operative was glowing with excitement after buying a genuine, battery-operated clearing saw from Tondeuse et Compagnie, a hole in the wall place to the north of Lyon. He decided to polish off the great day by taking in a show at a nearby theatre on Fourviere hill.
Well, along the way to the theatre, a funny thing happened. He spotted the squat unassuming entrance to the Lugdunum, the rest of which Zehrfuss, the architect, buried in Fourviere hill which stands above the village theatre. With time to kill, he figured why not. He made his way in and bought a ticket for a quick jaunt through the museum before the show. For reasons explained later, the live action theatre show didn’t happen. Nevertheless, he saw something interesting at the museum and left with a whole new understanding of the beginning of things.
The way it worked was straight forward. You pay your odol, get your ticket and start a spiralling descent down a cold concrete vortex like a dearly departed Roman soul on his way to see Pluto. Down, down, down you go into the bowels of Fourviere hill. Upon reaching the bottom of the vortex, it is with a mild sense of good fortune that rather than the drooling gaping maws of a three headed ill-tempered hound of hell, you are warmly welcomed by a lovely, life-size empennage of a horse. Good start so far.
The horse empennage is a bit jagged edged, with massive slashes on the righ flank and coated in green patina. Unlike the view of the boxer wearing version shown in the Monty Python’s “How to Recognize Different Parts of the Body” instructional video, we could see that a a certain something(s) had fallen off, leaving him just short of being completely anatomically correct. It was as if the sculptor gave up after having a few things go wrong on it just before he got to the important parts. By that we mean, the rest of the horse. Or maybe, the artist thought he had gained enough skill and talent to spring ahead with the rest of the horse, and decided he would start over with a horse of a different color.
According to our operative, it was a decent start for a horse statue, the curves and proportions were spot on, it had most of what one would find in that area of a stallion, and it made a good French start to a tour of a French museum. And that is about it. Artistically speaking, without the rest of the horse, a life sized horse’s patootie can’t really function any better than a Sling Empennage can function without the rest of the Sling TSi. Only a few most serious horse aficionados, and perhaps the occasional wierdo, would spend a lot of time admiring horses asses, and even fewer airplane fanatics would spend even less time fawning over airplane empennages. Most of us would spend more time with the rest of the horse, and of course the rest of the sling, focusing on the cabin, panel and engine.
Still, just as the Sculptor developed his skills beating his horse’s ass into shape, we here at Connecticut Slingers are using the skills and techniques gained and refined during the empennage build to use on the the nicer parts.
“Well Duh!”, and “Mon Dieu, it took you, like, forever to get to the point!”
While the French look for the rest of the horse back at the parking lot where they dug it up, we will put the skills gained on to the next part of the Sling AIFP build with earnest effort. We don’t want our empennage doing guard duty at the end of a ramp in a French tourist trap.
But first…
About the theatre. The place was an utter shambles, in desperate need of repair. The seats were gone, and there was grass and weeds growing all over the place. The attendant mentioned they could only do shows in the summer, when there wasn’t any rain, what with the roof missing for the past 2000 years. Well, remodeling permits do take time in France…
We were slowly making progress on our wings, finishing the flaps and installing our wingtips when the fuselage box came, with the entire fuselage flat packed into it IKEA style.
Interestingly enough, for us here at Connecticut Slingers, this coming-in-a-box feature proved useful immediately upon its arrival. We found that by keeping it shut until the wings were finished, our anxious and curious child labor was well motivated to finish the wings before they would be allowed to look inside.
With the staff motivated, and under the watchful gaze of our dear leader and mascot The Lord Slingungus, we could finish off the wings with the tip installation.
It wasn’t long before we found installing the tips with the wing with the wing upside down reduced the drama by quite a bit. We strapped a 4 foot long level along the spar, with enough sticking out to support the flare part of the wingtip. This ghetto grade approach worked nicely aligning the tip just right with the rest of the wing and ready for rivet holes to be drilled. Obviously, it takes but a modicum of cogitation to realize we could use the holes in the skins as guides for holes along most of the tip.
We say most, as the rear portion of the wingtip extends past the wing skins and covers the rear holes of rib 14 (P/N WG-RIB-014-R-F-1). It would be difficult to drill holes in the wing tip that would match up with the holes in the rib.
It was mentioned in a post on the sling builders blog that it is difficult to drill the holes for the trailing edge of rib 14 (P/N WG-RIB-014-R-F-1). We tried a few things, like making a template using a scrap of aluminum (by the way, if you are beyond the flat American universe, its pronounced “Alumin-ee-um” ) . As you can see from the photo, we got confused which led to a hole drilling frenzy and we had to abandon that approach.
Fortunately, our minions in Bureau of Research and Development in the Directorate of Clever Solutions came up with a simple idea.
Use tape. Painters tape to be specific. With the wingtip removed, we laid a piece of painter’s tape along the edge of the wing skin and rib 14 including the trailing end of the rib. We found painter’s tape worked well, it doesn’t stretch like electrical tape, and will peel off unlike duct tape. We carefully laid it flat, pressing it firmly in place making sure the edge of the tape was flush with the edge of the wing. Next, we found where the rivet holes are in the trailing section of the rib. They were easy to spot when we got an unoccupied staff droog to illuminate the holes from below with a flashlight. A few quick pokes with the awl at the luminescent holes and we had a template.
We peeled the tape back as far as the edge of the top and bottom skins and positioned the wingtip in place. It was all downhill from there, we simply stuck the now holey tape to the trailing end of the wingtip, carefully making sure it was straight. We then marked and drilled the holes with the guidance of the wing skins and the holey tape.
We were quite shocked to find it worked very well not looking like the metal Swiss cheese aluminum scrap we created while to use as a template. Rather, the wingtip holes were perfectly aligned with the holes in the rib, ready and easy to rivet. Mike Blythe would be proud.
Riveting the wing tips in place was a breeze, and with that done, we declared the wings complete, and thusly consigned to the Sling Wing SLings. leaving us feeling the same as the guy who made the life size horse’s butt stabled in the Lugdunum. A mix of accomplishment, and ever anxious to get on with the rest of it.
As we start with building the fuselage, we want to mention a few things from a construction and engineering perspective that are different from the wings and empennage. Interestingly, in the nice to haves department, the fuselage has conveniently more windows and doors than the wing. These are nice to haves. The great to haves are some Flight Appreciation Seats (FAS’s) instead of a lot of ribs filling the centre fuselage, a predicament something that was not found in the earliest airplanes, since there was no fuselage. All of this poses a challenge in the engineering department.
It wasn’t until early in the post neolithic period of aircraft design when, for marketing purposes, it was proposed to have some sort of thing to sit in rather than on a wing or a collection of sticks held together with sinew while appreciating a flight. There were some subtle benefits to this, It would keep the blasting wind from messing up a passenger’s hair, or sloughing off those big floppy hats ladies wore back then. As a bonus, It would also reduce drag, which increases speed, making trip times shorter, a good thing in onto itself due to the lack of lavatories in planes of the period.
The challenge was to make the fuselage structurally sound, able to handle the different loads during flight, such as those encountered in the barrel rolls Mr Blythe’s Attorney likes to do in Mr. Blythe’s personal Sling. In addition, to keep the inflight whining to a minimum, the occupants must be ensconced in an FAS in complete ergonomic comfort. Suffice it to say that it didn’t take long before early truss and geodesic style of fuselage construction appeared, and then promptly entered the quaint realm of low speed enthusiasts when monocoque and semi monocoque techniques came into vogue.
Monocoque styles made their debut with Eugene Ruchonnet’s Cigare, and the most famous was the Lockheed Vega. These were popular during the days leading into World War I and during the war, when builders wanted a sleek fuselage to wring out some more speed. These early monocoque fuselages involved artisanal techniques for construction, just like the Sling. Other than that there isn’t much in common.
Monocoque fuselages were produced using thin layers of wood bonded together using animal-based glues (this may explain what happened to the rest of the horse). It was a time consuming process of placing layers and layers of thin wood laminated over forms with the grain in a crisscross pattern to form a fuselage, A time-consuming process, even with all the added horse power in the glue.
Not too long after Napolean III dazzled his dinner guests with aluminum cutlery, Aluminum became cheap enough for use in fuselages, making construction faster and cheaper. Along with it came the advent of the semi monocoque fuselage which incorporated some elements of monocoque and some from truss designs. It is made up of the skin, nothing more than a thin sheet of aluminum, and a framework composed of vertical ribs and horizontal longerons which span between the ribs. As for the Sling, all of these parts are cut, stamped, pressed and rendered holey before being conveniently flat packed Ikea style into a nice plywood box. This is quite literally impossible to do with a a truss or geodesic style frame, which is hard to fold up. Okay, it is true the Quick build plan has a mostly built fuselage, but its missing FAS’s and a canopy, so it will fit in a box just fine.
First, dealing with our Tyco Monolith box full of flat packed fuselage that’s holding center stage.
The box had been sitting in our Sling Build Headquarters for more than a few months as we drank, ate, played video games, watched YouTube and procrastinated and finally finished up the wings and fuel tanks. Opening the box elicited the thought of Howard carter opening King Tut’s Tomb. We saw all sorts of wonderful things, including golden joysticks and torque tubes laying amongst lots of shiny little bits and pieces, ribs, bushings, plates, brackets, and all sorts of tchotchkes and what not.
We should mention here, dear reader, that we are on the slow train for this build in a two-car garage measuring 22 by 22 feet (6705.6mm by 6705.6mm, if you are under metric oppression.) So everything needs to be tucked away like dishes in an apartment in deepest Tokyo.
It was easy with the wings, they had fewer parts which we could stash in the Sling Parts Drying Rack or the Sling wing Slings and a few shelves. This worked fairly well. We went into bouts of consternated tizzies only a few times searching for that odd bracket or rivnut.
With the Fuselage, however, there is a staggering number of different parts, ranging from tiny to small to large to floppily gargantuan. All meant for several different subsystems.
A dim lightbulb went off our assembly staff that we could organize the parts based on sub system. Tail and centre fuselage parts go in the SPDR, and the controls, seats and heating would get their own boxes, and we would put the Dr. Who scarves of hardware parts in with the right subsystem. We sincerely hoped that would help.
This time, we would give them the spa treatment as we needed them, keeping the raw parts safe in their box until it is their turn, and no line cuts.
Next, we set about doing the not-at all-fun part of deburring allodining and priming them. Lots of YouTube watching was ahead. We shuddered at the thought, but it had to be done. We learned from doing the Empennage that doing all the parts at once and then consigning to them to the vast chaotic wilderness of our 484 square foot garage led to annoyingly expansive periods of time looking for a part when we needed it.
So first up in the Legos Fuselage Book was the rear fuselage rib assembly 1. Looking like something Jesco von Puttkamer would make after helping Herman Rorsarch replace a timing belt in Ford F150 over a can of Vienna sausages, it’s a piece that has just enough metal in all the right shapes and all the right places to secure the empennage to the rest of the plane, the equivalent of a pelvis on a rather sleek vertebrate.
In short order we had all the parts deburred, alodined and primed, with the assembly proceeding much more quickly than the hook thingy thanks to previous experience with the Empennage. It was looking great until we had our first hiccup.
It was rather odd, BKT-007 which is Bracket Horizontal Stabilizer Attachment, was too short on the part that sisters to the Rib 7 assembly. Ugh. Had to get a new one from Tedderfield. There wasn’t much we could do until it came, so we kept building.
We next moved on to the ribs using the jig which we lay the parts out on. That was straight forward, and the whole lot Ribs 2, 3, 4, 5 were assembled with ease. Oh sure, we had to redo the rivets ‘cause we did them in the wrong direction, but other than that, as easy as microwaving poptarts with a poptart button preprogrammed on the microwave.
Moving towards assembly, we did the Spa treatment on the rest of the tail parts, the little parts and the big parts, the skins and the longerons.
Longerons. Yes. Very long, these longerons. We had to get clever with these in the allodining department. We made a Longeron Allodining Tank out of a 10 foot long piece of 3 inch PVC with a cap at one end and a TEE fitting with a cleanouts at the other. We did the Longerons 3 or 4 at a time, inserting them through the end cleanout, filling the acid and Chromic acids solutions through the other cleanout. It was nice and factory work easy.
Of course, as we mentioned in one of our previous blogs we abandoned the notion of alodining skins, it wasn’t feasible, so we would give them a nice scuffing with a palm sander fitted with red scuff pads and a nice application of the 2-part epoxy on the interior facing side. It may be best to give the parts a nice rub down with MEK to remove the residue from the plastic peel.
Of course we gave the rest of the parts for the tail the usual spa treatment, which got the works.
Assembling the lot was straight forward, starting from the bottom up. This sets the plan for semi-monocoque, where frame pieces and skins are joined to provide the overall structural integrity. this is unlike the wing, where the frame is completely built before it is covered with the skins. With the Fuselage, we do start with assembling the rear most rib assembly, but after that, we assemble the framework with the skins as we build starting with the bottom skin and longerons.
The Legos book has an illustration showing the framework. We start with clecoing then riveting the bottom skin to longerons 6 7 and 8 and the ribs. The narrow end of the skin rivets to the rib 1 assembly, with additional longerons cable tied to the ribs. Even if we were to somehow permanently rivet this framework together, it would still be flimsy until we install the skins. at that point, the whole thing comes together, united in strength and solidarity.
Awe yes, installing the skins. The Legos book is a bit short in the descriptive department, Like all Legos books, it relies on pictures to do the explaining, in lieu of a thousand words each. So we have to study the pictures as intensely as NASA engineers would test a light bulb, as seen in the video below.
After studying the page for installing the lower side skins, it became clear the rear skins must go first then the front ones over lap them. That was easy enough, and in his teachings Evan Brunye tells that there should be little if any match drilling in the tail. Indeed, we found very little. The hard part was at the very end of the tail, were it took a firm pair of hands to get the skins to fit properly over the von Puttkamer sculpture, and cup the bottom skin. This meant fitting the red headed step child of the Rear Cover Skin (RF-SKN-006-C-A-2) in between the skin and the assembly. It is a tight fit, but it does fit without drilling, just as Brother Evan said. And Thank God we didn’t forget the rear cover skin. Amen.
Of course we did screw up something with the covering the rear rib assembly which meant redoing it, we’ll get to that next episode.
The side skins RF-SKN-004-C-C-1 and RF-SKN-104-C-C-3 overlap the rear skins on Rib this is a little unclear in the blow-up style picture in the Legos book, but it makes sense.
Applying the side skins was again, straight forward, hardly any drilling, except for cleanout from the primer. It was just a great, highly repetitive process enjoyed by the staff, up until we reached the column of rivets that go in the holes for the number 3 rib. The rivet holes in the skin just didn’t match up and were actually obscenely wildly way off. We tried all sorts of things, pulling and shifting the skin, to get the holes to match, but nothing worked. It was a real stumper, the skin matched the holes on all the other ribs and Longerons with no problem Finally, we realized either the skin was wrong, or the rib was wrong.
We had a hunch that it was the rib, given how well the holes in the skin matched everywhere else. So filled out the parts form, and waited for Scott out in Torrence to send us another package with the 2 bottom parts of Rib 3 (RF-RIB-302-R-C and RF-RIB-302-L-C).
We waited for them to come, and…