Chapter 19 – WINGS, Wings, wings

I started out today by removing the protective duct tape & nails used in bonding the pieces together for the LEFT wing’s FC2 section.  I also cut the 6″ wedge off the Left wing’s FC1 section for the hollow/inset Inboard end rib.

Chap 19 - FC1 End Rib Prep on Left wingBack on the Right wing, I drew a line & cut off a wedge at the most Inboard part on the front portion of the wing.  This will allow the front of the wing to align correctly with the fuselage-side strake later on after the strakes are built.

Chap 19 - Finalizing Wing ShapeChap 19 - Finalizing Wing ShapeChap 19 - Finalizing Wing ShapeI then whipped up some flox and floxed the jigs to the top wing surface by applying a small dab of flox every 6-12″ along the corner intersections of wing foam to wood jig (seen in the picture above).

I spent a couple of hours constructing a long work table for the wing builds and getting it as straight & level as possible.  Due to the size of the wings this new & improved work bench is much longer then the previous one.

I then unscrewed the wing jig base from its wood pedestal and placed the wing–in the jigs–bottom side up on the work table.  I leveled all the wing jigs to ensure they all matched & thus the wing washout (the shape of the wing as in how it twists, or “flows”) was as close to the intended design as possible.  Once all the jigs, and thus the wing, was as level as I could get it (there were some slight anomalous variances I mitigated as best possible, but that I could simply not eliminate) I hard mounted the jigs to the table using L-brackets & screws.

Chap 19 - Bottom Spar Cap Prep

Chap 19 - Bottom Spar Cap Prep

Chap 19 - Bottom Spar Cap Prep

I prepped a 1×2 strip of wood which will be used as a dam while laying up the 3″ UNI tape spar caps.  I covered the parts of the wood dam strip that will contact the layup with duct tape.  I then bondo’d & clamped the dam strip to the shear web at the inboard part of the wing where the aft wing section extends farther Inboard than the front part of the wing.

Chap 19 - Bottom Spar Cap PrepChap 19 - Bottom Spar Cap Prep

With the bondo on the dam cured & good to go, I taped off the edge of the spar cap (shear web glass) with plastic to protect the wing foam surfaces.  I also set up the 3″ UNI tape on its dispenser stand.

Chap 19 - Bottom Spar Cap PrepChap 19 - Bottom Spar Cap Prep

 

 

 

Chap 19 – Wings & Shear Web

Shear Web Construction . . . a couple of points of note.

First, I don’t think I’ve really covered what a shear web is exactly.  Partly, because I don’t know exactly.  Why? Because I’m not a friggin’ engineer!  A shear web is glassed using UNI in a hatch pattern that crosses the front of the current “top” of the wing (not the front portion that is rounded, but about halfway back and running down the entire middle of the wing).

The shear web starts on the top, travels forward 3″, then turns down the face of the shear web cap (again, this is in the middle of the wing) and then moves rearward 3″.  In essence, it creates a Π shape cap when the wing is positioned pointed upwards, as it is in the jig.  In this position, after the shear web is glassed, the front portion of the wing will get micro’d to the shear web and sit on the top of Π.  Once it all cures, and the wing is an entire unit, the left & right sides of Π will be recessed, deeper at the middle and shallower at the wing tip.  Then 3″ UNI tape will be laid in long strands onto the sides of Π in these recessed channels. (3″ UNI is not the same as UNI cloth, but very long thick strands of fiberglass traveling in one direction that essential cures into what can be described as a solid glass bar).

When the 3″ UNI tape is laid on the left & right side of Π which is actually the top of bottom of the wing, these create spar caps on the top and bottom of the wing.  These spar caps are connected to each other via the shear web, so that all the torsional forces that act on the wing in flight (bending, flexing, twisting) are transmitted from the top spar cap to the bottom, and vice versa through the shear web.  If the shear web was not present and it was only the spar caps, the wing foam alone could not handle the flight loads… and bad things would happen.  Thus sayeth Burt . . . (well, kinda, with a little paraphrasing!)  

Next, after a multi-hour long discussion with Randi (of the infamous Cozy Girrrls) a few weeks ago, I had acquired “the plan” on how to more easily lay up the shear web–again, using poor man’s pre-preg with a twist: aluminum foil– and the secrets for laying up the 3″ UNI tape spar caps.

Thus, without any further loquaciousness, I will get on with the build log . . .

I arranged some saw horses and prepped a long table for the shear web pre-preg.  I then measured, drew & marked up the plastic sheeting.  I prepped the wing foam at the shear web site & then pre-deployed epoxy & other glassing materials to the shop.  I laid out all the UNI glass (that was cut last night) & double checked everything one last time.

Chap 19 - Wing Build & Shear WebChap 19 - Wing Build... Shear WebChap 19 - Wing Build... Shear WebChap 19 - Wing Build... Shear Web

With Gina manning the epoxy production station (again, so NICE to have help!) I wetted out the UNI shear web pre-preg.

Chap 19 - Wing Build... Shear Web

Chap 19 - Wing Build... Shear Web

Once the pre-preg was good & wetted out, I micro’d the shear web foam.  I then replaced one of the plastic pre-preg sides with aluminum foil and translated the markings to the aluminum foil (these markings showed the center of the layup, both wing ends, and the 2 important “butt lines” [distance from aircraft centerline] that denoted the differences in UNI ply count).  I then flipped the entire pre-preg set-up & pulled off the remaining layer of plastic so that only the UNI plies were left attached to the aluminum foil.

Chap 19 - Wing Build... Shear Web

Chap 19 - Wing Build... Shear Web

Chap 19 - Wing Build... Shear Web

We then transferred the entire UNI pre-preg layup to the wing assembly and flipped it like a flapjack onto the micro’d shear web foam.  After getting all the markings aligned, we started vigorously squeegeeing the aluminum foil from the centerline of the layup out to remove any air & to set the glass onto the micro’d foam.  The aluminum foil was much stronger then I imagined it would be and really allowed for some hearty squeegeeing action.

Chap 19 - Wing Build... Shear Web

IMG_0014

Chap 19 - Wing Build... Shear Web

Chap 19 - Wing Build... Shear Web

After getting the glass squeegeed out & set, I began to pull sections of the aluminum foil off the layup and cut the edge of the glass with another Cozy Girrrl indorsed tool: “Dritz” electronic scissors.  I cannot even begin to tell any composites builder how amazing these scissors are & what a huge time-saver they turned out to be!  5-stars across the board on the Dritz scissors.  If you are a canard builder, get these scissors if you don’t have them.  Ok, I digress.

Chap 19 - Wing Build... Shear Web

After the UNI shear web was laid up, but with the epoxy still wet, it was time to attach the front portion of the wing (on top in this position).  We applied micro to the bottom of the FC4/5 assembly and then positioned it onto the shear-webbed aft wing assembly, and then peel plied the “sides” of the shear web (at this point technically the “sides” of the shear web are really “spar caps”).  Also, to ensure that the front portion of the wing was properly aligned with the rear part, all the jigs were re-bolted back together, encasing the new wing structure.

Chap 19 - Shear web done/wing one piece!I laid up 2 sets of 3-ply BID pads directly over the previously embedded aluminum extrusions & newly glassed UNI shear web as a base for 2 more 2024 Aluminum extrusions.  These 2 added extrusions were then attached & epoxied in place over the newly glassed shear web & 3-ply BID pads.  The new Inboard extrusion (LWA2) was approximately the same size, while the Outboard extrusion (LWA3) was a single longer extrusion that spanned the width of the wing/shear web and covered the 2 individual/ previously embedded extrusions.  To ensure the extrusions & glass coverings were securely in place, weights were added to compress the layups & squeeze out any air and/or excess epoxy.

Chap 19 - Shear Web...more extrusionsChap 19 - Shear Web... more extrusionsChap 19 - Shear Web...FC4/5 Attached

I went through and double-checked the shear web/spar cap layup, especially the edges.  I ensured the peel ply was applied correctly, the weights & extrusions looked right, and the front/back (top/bottom actually) spacing between the front & rear sections of the wing were correct.  Also, the spacing on the jigs looked good & the alignment was correctly maintained.

Shear web done & wing one piece!Shear web done & wing one piece!

 

Chapter 19 – Heavy Metal Wings

Ok, maybe not “heavy” metal, but definitely adding some 2024T3 aluminum extrusions to the wing build today.  And 2024 may not be heavy, but it is some very tough stuff.

So far so good… everything looked straight and the micro seams were looking good.

Chap 19 - Right Wing Build

I did have one minor issue, and again I think it comes back to how the wing cores are hot- wired (notice how I can use this as a root cause to the problem since I didn’t hot-wire the cores!).  When FC4 & FC5 were sitting so they were butted end-to-end, there was a small gap between these two foam sections, but only on one side of the seam.  I looked to sand the seam straight, but it would have caused either the inboard or outboard section to be short, and thus the front half of the wing short by just a tad.  After playing around with it a little bit, it didn’t really seem like that significant of an issue… at least nothing more than a little extra micro wouldn’t take care of.  In the end, after the 2 cores were micro’d together, there was about a 0.1″ gap in areas between the seam of the foam cores.  Nothing horrific, but enough to warrant injecting some more micro in the seam between the FC4 & FC5 foam sections.  Kind of like Botox, after a few injections it all looked pretty good!

Chap 19 - Need more . . .  Micro!Chap 19 - I gotta fever, for some . . . micro!

On FC1 there will be 3 hard points for attaching the wing to the CenterSection Spar.  Two of these hard points are Outboard (still on FC1 though) & one is very close to the Inboard edge of the wing.  With the previous cutout at the end of the wing (end rib), obviously there is easy access to the single hard point at the very Inboard edge.  But the 2 Outboard wing attach bolt hard points need an access point to put a wrench into the wing, at an angle nearly parallel to the surface of the wing . . . this needs to happen both on the top & bottom of the wing.  So troughs are dug into the foam and glassed, but then all but an access hole is left when thick aluminum plates are added where the bolt will go through, and a thin “L”- shaped piece of aluminum covers up the majority of the trough and will subsequently get covered with a lot of 3″ UNI tape that makes up a very thick (comparatively, we’re talking 1/2″ . . . of pure fiberglass!) wing spar cap that runs from the inside edge all the way to the outboard end of the wing, both on the top and bottom of the wing.

I prepped the foam for the wing access bolt hard points in all 3 locations on FC1.  I cut out the foam and shaped the channels for the access bolts on both the top and bottom of the wing on the Outboard side of FC1 (both the front & back side when it’s sticking straight up in the air).

Chap 19 - Wing Attach Bolt TroughsChap 19 - Wing Attach Bolt TroughsChap 19 - Wing Attach Bolt TroughsChap 19 - Wing Attach Bolt Troughs

After prepping the foam with a coat of thicker micro, I glassed in a 2-ply BID layup into each channel.  I then micro’d in the two 2024 aluminum extrusions (LWA4) so they sat level with the top (front) of the wing assembly as it was then situated.  I also micro’d in the lone aluminum extrusion (LWA6) on the Inboard edge so it too was flush with the top of the wing assembly.

Chap 19 - Wing Attach Bolt Extrusions

Chap 19 - Wing Attach Bolt Extrusions

Chap 19 - Wing Attach Bolt Extrusions

Chap 19 - Wing Attach Bolt Extrusions

After the BID layups had cured somewhat, I knife cut them so they were even with the foam surfaces on each side of the wing.  I then floxed in the thin “L”-shaped pieces to what will be the top and bottom surface of the Shear Web & Spar Caps, and held them in place with finish nails while the flox cured.

Chap 19 - Wing Attach Bolt Extrusions

Chap 19 - Wing Attach Bolt Extrusions

Meanwhile . . . while I was messing about with the wing bolt hard points, Gina was busy helping to fix a boo-boo that was right on the face of what will be the shear web.  She fashioned a foam plug to match the rather large chip that came off one the junctions of the major foam core sections at a top point where the foam was tapering very thin.  She taped off the area and when I had some micro whipped up for the bolt access channels, we micro’d the fix plug in place.

Chap 19 - An unfortunate boo-boo

Chap 19 - Boo-boo repair

After that was all taken care of, I focused on digging out the dead micro in the seams where the Shear Web will get glassed, while Gina taped plastic around all the wing areas OTHER than–and at edge of–the Shear Web to protect those areas from errant nasties while laying up the Shear Web.

Chap 19 - Prepping for Shear Web

Chap 19 - Prepped for Shear Web

 

 

Chapter 19 – Winging it!!

Today I got to do something on the build I haven’t done in a while, as you may have noticed . . . I only worked on one thing out of one chapter!  No multitasking!!

So, being military I like to name the major parts of the build and often make references in my notes by those names.  Thus, I have a codename, if you will, for the building of the wings:

OPERATION GOLIATH

Ha!

Ok, so let’s get to it…  today I bonded FC2 & FC3 together in the jig.

Chap 19 - Wings (FC2 & FC3 in jig)Chap 19 - Wings (FC2 & FC3 micro'd together)

Now the next step is something that is a pretty cool process, as Burt has many in his designs.  When the wings are finished, the inboard area on the back half of the wing (FC1) is recessed so that the aileron control components have somewhere to live.  This recessed area will be glassed on the top and bottom exterior (the wing upper and lower surfaces) and top, bottom and front (it’s a 3-sided piece-of-pie shape) on the interior.  This is done by chopping off the inboard side of the wing with a wood saw (no kidding!), cutting away a big middle wedge so that only a 0.6″ of the top, bottom, front wedged-shaped “ring” is left (what will be the surfaces for glassing) . . . observe:

Chap 19 - Wings (FC1 end rib cutout prep)

Chap 19 - Wings (FC1 end rib cutout prep)Chap 19 - Wings (FC1 end rib cutout prep)IMG_0006

You’ll notice, in true Wade fashion, that there’s a couple of extra “seams” when I micro’d it back together.  At some point in cutting off the outer 0.6″ edge it all came apart on me and ended up in two separate pieces.  No worries, foam is easy to get back together with that wonderful stuff we call micro!  The inside bottom of this pie-wedged shaped trough (as it sits in the pic below) will make up the inboard rib of the wing.  The hole in the pic will eventually house the aileron control tube.

Chap 19 - Wings (FC1 end rib cutout)

Chap 19 - Wings (FC1 end rib & FCs 2,3,4,5)

You can see in the background of the pic above that the top piece that makes up the corner of FC4 is micro’d to the main part of FC4.  At this point FC4 & FC5 are resting on FC2 & FC3, but they haven’t been attached to any other sections.

As you know, from time to time here in Germany some very friendly visitors stop in to check out what’s going on… here’s another one!

Another helpful visitor drops by . . .

After I put FC1 back together and got ‘er micro’d all up, I took some time to scrub down all the primered aluminum wing extrusions with Simple Green & 3M Scotch Brite pads.

I then came back to FC1 after the micro had cured, placed the big hunk of foam back into the middle of the end rib area to strengthen and protect the currently fragile foam and proceeded to bond FC1 to the FC2/3 unit.

This is probably not a surprise to anyone, but the wing cores were not cut to perfection and some monkeying around comes into play when getting not-perfect wing core pieces to go together in non-perfect wing jigs!  So, I had to play around a bit with the jig and FC1 to get it to line up on the end of FC2 just right.  That entailed propping up the trailing edge of FC1 a little bit to make sure it all stayed aligned.

Chap 19 - Right Wing (FC1 end rib)

Chap 19 - Wing Build (FC1 micro'd to FC2/3)

Chap 19 - Wing (FC1 micro'd to FC2/3 combo)

After getting the back half of the wing all put together, with FC1 attached nicely to the FC2/3 sections, I bonded the front parts of the wing, FC4 & FC5, together with micro.

Chap 19 - Wing (FC1 micro'd to FC2/3 combo)

Chap 19 - Wing (FCs 4 & 5 micro'd together)Chap 19 - Wing (FCs 4 & 5 micro'd together)

Chap 19 - Wing (FC1 micro'd to FC2/3 combo)

I also took some shots going up & down the leading edge.

Chap 19 - Wing Build (Leading Edge Shot)

Chap 19 - Wing Build (End view)

 

 

Fuselage/Gear Mockup & Wing Build

I final knife cut & sanded out the main landing gear tabs.  Then I took the gear outside & mounted it to the fuselage… it fit! (Whew!)

I then measured the respective gear legs to the “nose” centerline mark.  One side was 0.2″ closer to the CL mark than the other … oh well, I’ll mitigate that when I mount the axles.

Chap 9 - Gear MockupChap 9 - Gear MockupChap 9 - Gear MockupChap 9 - Gear Mockup

I tightened up the gear bolts & flipped the fuselage over so it was sitting on the gear.  It looked good!

Fuselage & Gear MockupFuselage & Gear MockupFuselage & Gear Mockup

I then hooked the battery up & tried out the landing brake in some what of a more “operational” setting!

And finally, before I put the fuselage away in storage, I played around with some urethane foam & cut/shaped a hellhole cover… kind of a pain.  But good experience.

Chap 24 - Hellhole CoverChap 24 - Hellhole Cover

After I put the fuselage away in its climate controlled storage facility (my dining room!), I did the final aligning, measuring & mounting of the wing jigs to the wing base… which was fairly time consuming to make sure the jigs were perfectly aligned, square, parallel, perpendicular . . . etc.

Chapter 19 - Wing Build

With the help of Gina & Kevin, I pulled out the Right wing cores, spread them on the portable workbench outside, and aligned them all together.

Chapter 19 - Wing Build

After duct-taping the foam edges to protect the foam as much as possible from stray wayward micro, we micro’d the core pieces together (FC1, FC2, FC3, FC5) and set them in the garage to fully cure.  I should point out that there are 5 major sections of  wing cores that make up the wing.  Starting at the rear of the wing, on the inboard side (nearest the fuselage) is where the counting starts.  The back half of the wing has 3 major sections:  FC1 (INBD), FC2 (Middle), and FC3 (OUTBD).  The front half of the wing only has two major sections, and it actually starts in the middle of the wing (since the strake makes up what constitutes the “Inboard” wing) and moves outboard.  The front major sections are FC4 (Middle) and FC5 (OUTBD).  Hopefully this will help put things in context whilst discussing wing core sections.

IMG_0024Chapter 19 - Wing BuildChapter 19 - Wing BuildChapter 19 - Wing BuildAfter the micro started setting up, I very carefully slid the first core segment into the wood wing jigs.  I set the front wing half core on top of the rear wing half as you can see in the pic above.  [This was just for testing the fit & picture purposes.  The front wing core was not micro’d to the rear wing core at this point].  Since the micro was drying, we removed all the tape before it became a permanent part of the wing makeup (micro is some tough stuff… especially with tape!).

Chapter 19 - Wing BuildChapter 19 - Wing Build

 

Chap 9 – Final Main Gear Build!

I hand sanded the landing gear tabs & used the Perma-Grit tools to create a beveled edge at the tab-to-gear bow junction.

Chapter 9 - Main Landing Gear

I used the small round Perma-Grit to again re-bore & open the land gear tube holes.

I once again had a friendly visitor stop by… he hung around for a little while and then went on his way (with some assistance!).

I mounted the steel landing gear tubes into place with flox, then immediately floxed & glassed large AN washers onto the outside of the tabs with 2-ply BID layups.

Chapter 9 - Main Landing Gear

I then carved foam wedges as “ramps” for the landing gear tubes & micro’d them into place.  I then covered the micro’d ramps with 2-ply BID layups.  These ramps allow for glass to hold the steel tubes in place, but still have a smooth transition to the base of the landing gear bow.

Chapter 9 - Main Landing GearChapter 9 - Main Landing GearChapter 9 - Main Landing GearChapter 9 - Main Landing Gear

In between the drying stages above, I knife edged all the new tab edges.

Since the main landing gear glass was complete, I turned my attention to the wing build.  My first task was a 5-ply test layup for the 3″ UNI tape that is used in the wing, CS spar and canard spar caps.  Over the years there have been different manufacturers & suppliers of this 3″ UNI tape, so to ensure the spar caps are the correct thickness, and thus the correct strength, the width of the UNI plies must be tested.  This test layup procedure is spelled out in the Canard Pusher (CP) newsletter #25 on page 6.  If the 5 plies are too thin, then the solution is to simply add more plies, which is also spelled out in the CPs.

CP 25 pg 6 - 5-ply spar cap thickness testAs my 5-ply test layup was curing, I went back out to the shop and finished mounting my wing jigs to the wood base.

Chap 19 - Wing Jigs

 

 

Aluminum, Post Cure, Wings & Gear

The temp on my cocooned post-curing fuselage stayed over 122°F until around 0530 am this morning.  The cooling temps overnight finally caught up & the temp began to fall, albeit slowly.  All-in-all I got almost 14 hours of 122°+ F temps plus quite a few hours more at the 115°+ F mark.  I let it continue for another few hours and then began to turn off the heaters one by one to slowly bring the fuselage down to ambient temp.  I turned off the first of 4 heaters at 0900.  I turned off another heater at 1215, turned down one of the two remaining heaters to low, and opened up the back of the post cure tent.  By 1430 all the heaters were off and I let it continue to slowly cool down.

Back to the main gear, I removed the blocks and the clamps from the gear tabs.  Layups looked good.

From there, I took the now thoroughly dried Alodined aluminum extrusion pieces out to the back patio.  I wasn’t overly thrilled with the quality of my Alodining process, so I decided to add another layer of corrosion control on the aluminum parts by adding a couple of coats of primer.  But, to ensure that the glass would grip to a primer base that itself was gripped firmly to the aluminum surface, all the pieces will be lightly sanded and the prepped via a wash down with Simple Green and 3M pads to remove any “loose” and/or weak primer (this is how I prepped parts when I shot paint on my chopper project… Simple Green works great and is completely clean chemically).

Aluminum Extrusions (Ch's 14, 16, 19)Aluminum Extrusions (Ch's 14, 16, 19)After the fuselage was at ambient temperature, I took apart the fuselage post-curing setup. It all came down fairly quickly.  I double checked the fuselage with my levels and it seemed to have worked.  Without the weights in the fuselage, the longerons leveled out true and equal all the way around.

Fuselage Post Cure

Fuselage Post CureFuselage Post CureFuselage Post CureFuselage Post Cure

I then spent over an hour cleaning and organizing the shop.  I have a lot of epoxy to use. So in order to actually save the money I spent on the epoxy here in Germany I’m focusing more on the actual building and not so much on cleaning the shop back to a spit-polish after every chapter.  I only have until October before I have to deploy to Tampa for 6 months, so I’m trying to get every bit of building in that I can.  This is also another reason why you’ll see me building out of Chapter sequence, to get the biggest bang for my buck epoxy-wise.  And since I have help right now with Gina being available to cut glass and mix epoxy, I’ll be focusing on the wings next and getting as much done on those as possible since they simply use the most amount of epoxy.  That being said, I’ll still have a lot of epoxy left even after the wings are glassed, but they will definitely take the biggest bite out of my epoxy stock.

After the shop was cleaned & put back to decent shape, I primed the other side of my aluminum parts.

I then reinserted the Landing Brake Actuator into the fuselage.

After all my odd & end jobs were completed, I started prepping for the Right Wing build.  Since the garage floor is so uneven, I decided to simply build a wood base for the wing jigs.

Chapter 19 - WingsAfter the base was complete, I located it in the center of the garage and began the process of mounting the wing jigs to it.

Chapter 19 - WingsAfter I got the first few wing jigs mounted, I took a break from the jigs and went back to work on the main landing gear.  I cut & sanded the inside gear tab layups to match the outside gear tabs.

Chapter 9 - Main Landing GearChapter 9 - Main Landing GearI then redrilled the 5/8″ holes for the final time & called it a night.

Chapter 9 - Main Landing Gear

 

Aluminum Stuff & Landing Gear . . .

Finally got some Alumiprep to go with my Alodine!  If I haven’t covered Alodine earlier, it is simply a corrosion protection application to keep aluminum (yes, aluminum does corrode!) from deteriorating and losing strength over time.  This is especially important for composite airplanes where these metal extrusions are embedded into the foam & glass and can no longer be assessed or examined for any corrosion–for the life of the plane–without actually tearing into the glass to see it.

The Alodine process is fairly simple:  the Alumiprep is an acid that does a super-scrub on the part to clean (etch) it.  The part is soaked in Alumiprep for a couple of minutes.  Then the part is rinsed off with water and put into the Alodine for a couple of minutes where it turns a greenish-goldish-brown & receives its corrosion protective coating.  It’s rinsed with water once again and allowed to dry.

Click here for a good video showing How to Acid Etch and Alodine Aluminum.

I also found some Rosin Core Solder for the radio antennas that will be embedded in the wings, winglets & canard.  Also had to pick up 2 more portable heaters at the base and press them into service.

I used the Dremel & mini belt sander to make the 0.1″ & 0.2″ rounded-over edges on the aluminum extrusions.  I also cut out & made the GIB shoulder harness seatbelt tabs.

Aluminum Extrusions (Ch's 14, 16, 19)Chap 14 - Rear Seatbelt Upper Mount TabsChap 14 - Rear Top Seatbelt Mounting TabsI Alodined all the cut aluminum pieces and set them up to dry.  I had a sneaking suspicion that my Alodine was a little on the old side.  No matter what I did, pre-cleaning, leaving the piece in either solution for significantly longer, it didn’t seem to change the intensity–either light or dark–of the Alodined parts.

Alodined Aluminum Extrusions (Ch's 14, 16, 19)A little before 1600 my Post-Curing fuselage hit 122°F.  I’m going to keep it at that temp for at least a good 10-12 hours, and hopefully up to 15 hours.  Overnight may get a little problematic maintaining that 122°F since ambient temps tend to naturally fall off drastically here in Germany.

I laid up the inside glass on both the main gear tabs.  I also glassed a 3-ply BID layup on the outside of one of the tabs that seemed a bit thin (the ply-count was good, but the compression from the clamp appeared to have pushed the glass a little down towards the base of the tab, leaving the top a little thinner as compared to the other 3 tabs).

Chap 9 - Main Landing Gear Build

After a couple of hours had passed I knife trimmed the glass & cleaned up the edges… the layups looked good!

 

 

Extrusions & Fuselage Post Curing

I cut all the aluminum extrusions (LWAs) for the wings & CS spar that are spelled out in Chapters 14 & 16.

LWA Alum Extrusions - Ch's 14 & 16LWA Alum Extrusions - Ch's 14 & 16I then removed the clamps from the flox gear repair & did a mock install on the fuselage… Success!

Chapter 9 - Main Gear Mock UpChapter 9 - Main Gear Mock UpI prepped the fuselage for Post Cure & spent a couple of hours locking in the fuselage so that it was level to within 0.1° across the longerons in all directions.

Fuselage Post CureFuselage Post CureFuselage Post Cure

I covered the fuselage with a foil covered thermal barrier “tent” (or cocoon) and placed 3 portable heaters inside the barrier.  I started the post cure at 3:30 am and the first average temperature reading was 105-107°F.

Fuselage Post Cure

Chapter 9 – Main Gear Build (& consoles)

I knife trimmed the Right front & Left rear consoles.  I marked up the dimensions on the Right front control console, and then cut out the panel for the control stick & seatbelt access (yes, in my haste I cut the seatbelt cutout too narrow, and simply left it to cut wider later on) . . . I also removed the peel ply.

Chap 16 - Right front armrest consoleChap 16 - Right front armrest consoleI then removed the peel ply from the Left rear console & cleaned up the edges a bit more.

Chap 24 - Left rear armrest consoleChap 24 - Left rear armrest consoleI then took the Right front console out to the fuselage to mock it up & check out how it fit.

Chap 16 - Right front armrest console

After I finished for the day with the consoles, I removed the clamped wood blocks and removed the main landing gear out of its mount.

Chap 9 - Main Landing Gear BuildChap 9 - Main Landing Gear Build

I then took the main gear outside & put in on the folding table (my portable workbench).  At first, I started to trim the excess cured glass by using a coping saw, but that didn’t last very long.  I quickly switched to something a bit more electro-mechanical, pulling out the Bosch saber saw!  It worked great (read: “fast”) and I trimmed the excess glass on the tabs down to within a respectable 0.1″ of the wood templates.

Chap 9 - Main Landing Gear BuildChap 9 - Main Landing Gear Build

Chap 9 - Main Landing Gear BuildChap 9 - Main Landing Gear Build

Chap 9 - Main Landing Gear Build

Chap 9 - Main Landing Gear BuildI Dremelled the gear-tab to gear-leg junctions to get a smooth, round, flowing edge for all the tabs.  With the Dremel I was also able to clean up & smooth out the saber saw marks around the outer edge of the tabs.

Chap 9 - Main Landing Gear BuildChap 9 - Main Landing Gear BuildI marked the center of the holes & drilled a 1/8″ pilot hole to check that I was centered in the hole (the 5/8″ hole of the wood jig).

Chap 9 - Main Landing Gear BuildChap 9 - Main Landing Gear BuildOnce I was centered, I drilled 3/8″ pilot holes & then used the 5/8″ arbor bit to drill the main landing gear holes… it worked very well!

Chap 9 - Main Landing Gear BuildChap 9 - Main Landing Gear BuildChap 9 - Main Landing Gear BuildChap 9 - Main Landing Gear BuildChap 9 - Main Landing Gear BuildI tried to insert the steel LMGA tubes into the holes, but they wouldn’t go in.  I used my round Perma-Grit tools to bore out the holes a little wider, going very slowly and removing just a very little bit at a time.  It was a fair amount of work & took about an hour to do, but I definitely wanted to ensure the fit was tight and the holes weren’t bored out too wide.  Also, while boring out the holes I realized that the final fit should be without the wood jigs attached.  So I popped the wood jigs off, finished boring the holes and then spent about another hour digging, sanding, grinding, clawing and scratching out the dried (or should I say cemented!) bondo.

Chap 9 - Main Landing Gear Build

Well, I think I’ve shared my personal philosophy on building an airplane.  I’ve said over & over again that building any airplane is simply having the perseverance during the build to  repeatedly fix the things you royally screw up.  And this my friends, was one of those times.  As I was sanding the tabs, I noticed a dark line near the inside of the tab.  I sanded it down a little and messed around with it, but it was still there.  I then realized it was probably plastic from the peel ply layers.  I confirmed this by sticking in a razor blade and digging out some plastic!  That’s when I deftly thought: if it was on this side . . . ?!  Yep, there it was on the tab opposite the one I was working on.  I realized that with it being on both sides it wasn’t simply an anomaly, it was something serious & bad . . . I took the gear out to the garage and marked the edges of the tab glass and put a couple of X’s on each side for alignment purposes.  I then put some towels down on the floor, grabbed a rubber mallet and hit it a few times.  At first it didn’t seemed to do anything and all appeared solid, but I wasn’t overly convinced so I gave it a couple more good whacks and off it popped.  Smooth and shiny on the inside.

Well, I made a few phone calls & talked it through.  After a bit of discussion, I finally decided to sand each side down and flox it back on.  Besides bouncing it off some other bubbas, a few key things helped me in that decision.  First, flox is some tough stuff & it’s structural.  Second, the effort that it took me to knock the tab glass off with only a layer of plastic between the plies was significant, serving as a testament to just how much grip strength epoxy has in general–that a layer of plastic would hold so well.  And third, the configuration of the landing gear tabs has the steel LMGA tube floxed across and through each side of the tab holes, then into all of the plies on the piece that was knocked off–with the remaining plies still left on the gear–and the soon-to-be inner plies that I would glass in.  Thus, I decided I would proceed with the flox repair.

Unfortunately, the only pictures I have were after all that took place, since I was in emergency response mode and not concerned about documenting anything until afterwards.  You can see in the pics below that the flox has just been applied and the gear is back in the workbench mount with a myriad of clamps holding it tightly back into place.

Chap 9 - Main Landing Gear Build Chap 9 - Main Landing Gear BuildChap 9 - Main Landing Gear BuildI checked it out before I went to bed. . . the clamps had held it in exactly the same spot, with no slipping or movement, so I called it a night.