The Empennage
The last piece of fire wood stacked. The last potato pealed. The last step to the top of the mountain. The last drop of oil emptying from the last quart into the oil filler at the end of the oil change. All minor victories. Granting that joyful relief laden sense of accomplishment. But how tenuous. The rock of Sisyphus is always in every task…
A Horribly Mangled Part
It was a bright Spring Day, the spar pieces were cleaned, allodined and painted. They were all in the Sling Parts Drying Rack, (SPDR) dangling in the warm evening sun, as the wind gently made them swing. And then, the wind blew stronger, harder, with forceful brutality. The SPDR succumbed, fell over a pile of tennis stuff and a bicycle, spilling a carnage of Sling parts all over the floor. One piece, a horizontal stabilizer spar was terribly mangled in the carnage. what a handsome brace of moose antlers this was. Panic despair, hand wringing. Mike Blythe would be very upset, very upset indeed.
Fortunately, the rest of the parts miraculously survived. But before we moved on, we made a quick consultation with Mssr. D’Assonville at TAF World Head Quarters in California concerning the mutilated piece, with a request that Mike Blythe be kept unawares.
Almost immediately we got a gracious and reassuring email from none other than Mike Blythe himself requesting photos!
We timidly sent the incriminating photos of the destruction to Mike. We included them here to illustrate the magnitude of the damage. The Connecticut Slingers Bureau of Blogging standards has approved the inclusion, but reminds you dear reader, if you of sensitive of heart, or are of sensitive towards graphic pictures of traumatized metal, quickly click on this: photo of a nice little kitty.
Now for the rest of us capable of dealing with the harsh cruel realities of Sling building, let’s examine the damage. Se the photo below.
The horrific damage to the horizontal stabilizer spar
A few minutes later, Mike assured us that it wasn’t that bad, and with some proper tender loving care it would be good as new! He wasn’t even mad, and probably found the whole affair amusing enough to smile under his COVID, mask.
Well, with some careful bending and gentle prying with a pair of pliers, surgery complete. the spar was saved. On to the assembly. Hopefully Mike Blyth will burn the photos, just not onto a CD ROM.
An amused Mike Blyth enjoying Covid.
The Building Part
Just like tinker toys, legos, erector sets and all our other favorite fun things the Sling kit comes with an instruction booklet that has lots of pictures which we always pour over, carefully reading the instructions, very, very carefully. and then do some strategery to make up for all the missing notes.
We thought it would be easier to do the frames for the empenage first, and then put the skins on.
That being said, we started with what the people at Sling headquarters refer to as a BCW Swing Arm Assembly. Not a very tech sounding name. lets give it a proper techie name, like the Hook Thingy since that what it looked like. It was the singularly most interesting component of the whole empennage. It was small, and seemed straight forward enough, not to mention that it looked like a hook.
In fact, as easy as it looked, we still screwed it up. We began with assembling it with cleco’s, and then installed the bolts and spacers as we saw in the instructions. We were supposed to tighten the AN3 bolts to a torque of 1.7 ft/lbs. and that’s when we over did it with our new Gedore Dremomentschlussel 4549-00 torque wrench. We aren’t blaming the equipment here, it’s the thing that happens with every freakin’ cool tool. You just can’t resist the urge try it just one more time, and soon you have gotten carried away. In this case, it’s the little clickity click when you are turning the wrench and it reaches just the right torque. That’s what did it. In our wrench clicking zeal we tightened the nut and bolt we were not supposed to just so we could hear the click just one more time.
Clecoing the Hook Thingy, or the BCW Swing Arm Assembly to the layity.
So, we had to back track and loosen them once we realized they weren’t supposed to be tightened. Not the worst thing, nope, certainly not. Sisyphus’ rock teetered at the top but stayed…thus far.
Torquing the bolts on the Hook thingy
With the hook thingy done, we moved on to the Horizontal Stabilizer. It was the closest thing to a rectangle and easy to envision what it was supposed to look like. We did pretty well with it and since the Fiasco with the SPDR we were itching to find how well the bent part would fit. We needn’t have worried. In a couple of hours we had the ribs and spars clecoed together nicely, including the brutalized spar. With clecoing done, we wasted no time installing our first rivet in the main spar using the Milwaukee 2552-20 M12 Riveting tool. We triumphantly labeled the first rivet with a tremendous sense of accomplishment, then we watch more Youtube while doing the rest of the riveting.
Once in a horrible state of disfigurement, the Horizontal spar piece is salvaged and finds its home.
1The Officially Official First Rivet
One thing that was a bit off was the horizontal stabilizer ribs (HS-RIB-001-X-A-0) which were buckled slightly when we installed the rear spar channels (HS-CHL-002-X-F-2). They could be straightened when we held them by hand. We consulted with Monsieur D’assonville, who said “Il serait bon.” so we rolled with them as was. Other than that, we got the frames for the rudder and vertical stabilizer clecoed and riveted together without too much fuss.
Getting the Horizontal Stabilizer ready for the Rivets!
Then came the elevator. That was a bit frustrating in a forehead slapping tax return Sisyphian sort of way.
For the most part the elevator went together smoothly. All of the pieces had been riveted together nice and neat and real pretty with shocking accuracy. It was gorgeous. The puke green primer was accented by the Industrial steampunk silvery aluminum rivets, and The hook thingy gave it some 3-dimensional appeal.
All was Spring morning flowery lovely, except for just one little detail. Just an eensy one.
We used the 3.2 x 8mm Alu Domed Rivet (Multigrip) instead of 3.2 x 13.6mm Alu Domed Rivet (Multigrip) to hold the Centre Elevator Channel (EL-CHL-002-C-E-1), and both Internal Centre Plates (EL-PLT-001-C-E-0) and both External Elevator Centre Plate (EL-PLT-002-C-E-0) to the elevator spar.
Bolting, riveting and getting the hook thingy on real good, so we can just take it off again. we torqued the nuts down and numbered them so we can refer to them in our bolt torquing table.
Well, we suppose it was the proper time to quote the operator at the controls of Chernobyl uttered on April 26, 1986:
“OOPS!”
Out came the 3.2mm drill bit, and a few minutes of drill toil later, we had just two rivets on either side of the elevator yes, just two on each side holding the trio of parts to the elevator spar in a most taunting manner. They were right behind the shaft of the hook thingy, where there was no way to get to it with the drill bit. This is definitely earning a place in the butt chaffing life events file.
So now we had to pull the hook thingy off, which was held on by two 4.0 x 12mm S/S domed rivets (HW-RIV-454-X-X-0), two EL-ANG-001-R-F-0 Control Horn Mount Angles (EL-ANG-001-R-F-0) each held on with six 4.0 x 10mm Alu Domed Rivets (Multigrip) (HW-RIV-153-X-X-0), and four AN-5A bolts ( HW-ANB-305-X-X-0) with four AN3 Washers (HW-ANW-030-X-X-0) each carefully torqued down with four Nyloc Locknuts (HW-ANL-030-R-X-0 AN3). Penance is tough.
Then, an Epiphany.
After enough strategic drilling and unbolting, we found we could slip the hook thingy around in its little home and when it was in just the right position it was clear of the rivets. maybe we wouldn’t need to remove the hook thingy off completely. Hallelujah.
Indeed, the the last few rivets holding the pieces together were quick easy ro remove. Hallelujah and Victory.
Then in went the correct rivets, slick as a cup of custard, and soon after that we got the hook thingy reattached, except for the 2 big stainless steel rivets which we didn’t have extras. No Problem. We’ll put those in later. (We made a call to Doug over to Custom Aircraft Builders, who would track down some).
We were in the midst of appreciating the work of art laid resplendent on the luxurious Home Depot cast off carpet runner and discovered the Internal Elevator Centre Plate, (EL-PLT-002-C-E-0) lying on the carpet taunting us in that-petulant-little-part-full-of-itself way that only small parts left over from a rebuild can do.
My God, It was 10:00 at night, and we were anthropomorphizing airplane parts. Not a good sign.
The next day we drilled out the rivets, Again. undid the bolts, Again. Moved the hook thingy out of the way. Again. Pulled the last rivets holding all the parts to the elevator spar Again, and put it all back together. Again, only this time with the now demur Internal Elevator Centre Plate compliant and in its proper place.
Success, there is hope for us yet!
With the elevator framing done, it was time to do the skins. This was the most stunning part of the whole work on the Empenage. Well, we did have one of the ribs tuck under the rib at the end, but another call to Mssr. D’assonville, who said “Jusque pliez-le droit en arrière, et il serait bon”. good enough. it worked.
The bent elevator rib. The nose end is tucking into the interior of the elevator
We literally had no real problems other than that. the rivet holes in the skins matched the holes in the ribs and spars quite nicely. Very little drilling at all. Well, we did do a thimble full of fitting and fibbling, using an awl through a hole and clecoing the one next to it. This went for the Horizontal Stabilizer and the Elevator as well as the Vertical Stabilizer and rudder. It was suspiciously too easy.
To waylay our suspicions of something must be wrong, we did the alignment check as per the instructions using the Laser alignment tool from Coastal Tool.
Suffice it to say that was tedious, especially drawing the line perfectly down the middle of the ribs at the ends of the HS. We did our best with what Teutonic accuracy we could muster, measuring the distances precisely with calipers and a well sharpened pencil to mark the line. It was encouraging to see the line matched up with the middle of the 1/4” hole and the rivet holding the in the 4th rib onto the end of the front spar.
Finally, We shined a laser line on the end rib using the Dewalt laser level from Coastal tool in West Hartford. Without much trouble, we got the line on the left end of the stabilizer matched up nicely and level to the line using wooden shims and clamps. Once that was stabilized and firmly clamped down, the moment of truth was upon us. With baited breath, we checked the line on the rib at the other end of the piece.
And…
By some insanely ridiculous technicolor magic unicorn miracle, like a cop not giving you a ticket, the two ends were perfectly aligned! The laser matched the pencil lines at both ends, we double checked with glee, both pieces. Wahoo!!!
The laser reveals a nicely aligned elevator, it covers the pencil line drawn between the middle rivets in the end pf the Horizontal Stabilizer.
We finished off the skin with rivets, and on that bright glorious spring day, we declared victory. At least for the Horizontal Stabilizer.
The Elevator was a bit more difficult because the mounting process required inserting bolts into the hinge brackets through little holes while it was in the proximity of the Horizontal Stabilizer. We didn’t have a little kid with tiny hands to reach into the cutouts at the front of the elevator to stick the bolts in holes of the mount brackets, so we used a pair of needle nose pliers. We would position the bolt (we got the right size from Holdridges) using the pliers, and pushed/wriggled it in while trying to keep the elevator and horizontal stabilizer brackets aligned. It was difficult, we had to have the elevator in a state of deflection, so the holes in the elevator skin could be accessed. laying it flat even with the Horizontal Stabilizer would block the hole.
We ended up laying the stabilizer flat on the Home Depot carpet and one minion would hold it steady so the other minion can insert the bolts. We didn’t worry about the finger scratches from poking around in the holes, bandaids were cheap enough.
The came the end caps. The end caps. Ugh the end caps. And the Rudder. And the vertical Stabilizer.
Well. The end caps were hard to fit, especially since in our dimpling zeal we dimpled the holes on the edges where the caps were to rivet on. Still we got close awfully close, on at least one of the caps. Chalk this up to not using the wrap around strap method, instead we held in place by hand, marked and drilled. We will do it over. Later.
The photo shows us doing the end cap WRONG. Well, after we did it wrong. Instead of dimpling the elevator skin holes after we test fitted the end caps and match drilled the holes in the end cap, we made that mistake of going crazy with the dimpler and dimpled elevator skin holes at the same time we did the other skins. That wasn’t really the worst of it. we didn’t use the ratchet strap method here to get the end caps into proper position and it shows. the ends don’t line up, leaving gaps between the cap and elevator skin front edges. The right one isn’t too bad, but the left one sticks out like a tetanus encrusted nail. may have to do it over.
So with the rudder and vertical stabilizer frames done, we noticed that if we did the skins on them, we may be creating problems. Kind of like bolting and riveting the hook thingy on the elevator right away. If we installed the VOR antenna on the vertical stabilizer, we would have difficulty storing it damage free, what with the wiry ends of the antenna twanging all about as we stuck it up on the shelf. And with the rudder, well, the end cap would have the same deal, a delicate blinky light on top of it just waiting to be smooshed over the next several months of building. We would wait to finish those until we get the fuselage built.
Next: Wing Art, and lots more alchemy, that didn’t work.