Chapter 6 Part 2 – Fuselage Assembly

Welcome to Germany!

Chapter 6 – Part Deux (… or zwei!)

1 May 2012 —Today starts the actual unpacking of the boat, or shall I say, the fuselage.  Apparently my next door neighbors thought it would be cute to pull a fast one on me!  When talking in my garage/shop one day, they asked me what I was going identify this “thing” (said snidely) sitting in my garage that I was going to send over to Germany.   Well, a few weeks earlier I had seen on one of the blogs where a guy had shipped his fuselage as a “boat,” which I thought was pretty darn funny.  So I snarkily (it’s a habit of mine!) said, “a boat.”

Well, due to a scheduling SNAFU in Virginia, the movers had picked up my fuselage while I was at the firing range.  Luckily, my ‘trusty’ neighbors helped out with overseeing the movers pack my stuff.  Well, apparently they told the movers it was just, in fact, a boat.  What made it really funny was fast forward three months later in Germany when one of the guys unloading the truck asked me where I wanted my “boat.”  I thought his English was a little shaky!  After a few repeats, and a growingly impatient mover, I finally understood what he was saying and ran out to the moving truck to see them, in fact, lowering “a boat” out of the truck!  Well played my friends . . . well played!

Pics of unpacking “the fragile boat”!!!

Unpacking the fuselage (aka "boat")

•••

9 May 2012 — As for the actual build in Germany, I’m starting out with a deficit: I didn’t realize until after I unpacked my fuselage here in Germany that the movers had cranked down too hard on the cargo straps and cracked the lower longerons (stringers) in two places and crushed the foam in the lower middle section of the fuselage (I had briefed the moving crew on how to pack it and tie it down… for some mysterious reason they didn’t listen).  So, while April was a month of preparations, May will be a month of fuselage repairs!

Actually this is back to Chapter 5 Step 2 — (Re)attaching the Longerons!

9 May 12

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As you can see, the damage is fairly extensive.  Although I have tons of BID and UNI cloth on hand, I don’t have any lengths of triangular Spruce, so I immediately ordered lengths of 3/4″ triangular longerons from Aircraft Spruce.   My next step is to prepare a plan for repairing this fuselage damage.
One thing I’m concerned about specifically is the curvature of the triangular stringers on each side of the fuselage.  Where the breaks occurred, it’s feasible in my mind that the stringers won’t hold the curved shape of the fuselage once the repair pieces are installed.  That will be something I take into account as I repair the damages.  The reason behind this is that the bulkheads act as a sort of fulcrum that the lower longerons are “bent” around.
Fuselage DamageFuselage Damage
Fuselage (with damage)
In addition to repairing the “newly” damaged fuselage, remember I still have to repair and then reskin the back half of the fuselage bottom as well, as you can see in the pics below.
IMG_0381 - Copy
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Luckily, if you look at the pic of my house workshop, I have a small stockpile of spare fuselage sidewall foam under the workbench that I just happened to throw serendipitously into my household shipment… so I won’t need to buy any more of this foam and have it shipped over here!
House workshop (note spare foam under work bench)
•••

12 May 2012 — In preparation for starting back into my airplane building, I needed to get some epoxy.  My initial research held true and I was able to buy a lot of MGS (for some reason MGS in Germany is sold under the name Larit) epoxy and hardener for a LOT less than in the States.  And best of all:  NO SHIPPING FEES!!!

Today I went to Stuttgart and picked up 6.6 gallons of MGS 285 epoxy from the “local” epoxy vendor, Lange+Ritter.  Larit has the same specs as MGS and follows the same numbering scheme.  Luckily I had my documentation from the US in case I needed to double-check any info considering all the labels are in German.  Also, picked up two 1.3 gal jugs of the slow hardener and one 1.3 gal jug of the fast hardener.

Larit (MGS) Epoxy & Hardener

The first step in the fuselage repair is to make foam inserts to replace the crushed foam on the fuselage.  Like I said above, luckily I brought a bunch of spare foam with me.  The one slight issue I have with the foam is that I don’t have any pieces long enough, so I’ll have to micro two pieces together.  No worries . . . let the repairs begin!

Prepping spare foam fuselage repair inserts for micro•••

13 May 2012 —So here we go . . .  Lock & load!  Tonight I’m starting on the repairs to the fuselage damaged in transit from Virginia to Germany.  The first thing I did was to mark off the cracked and damaged areas on the lower fuselage sides (the fuselage is shown inverted in all the following repair pics).

Lower fuselage repairI marked off the minimum area possible to be removed to a) keep as much of the original foam and fiberglass intact as possible to maximize structural integrity, and b) use the least amount of foam as possible for the repair inserts.

I used a battery powered thin-kerfed circular saw and a “Fein” tool to cut out the damaged areas.

IMG_0395Lower fuselage repair

 

 

 

 

 

 

 

I took my time to ensure I got as nice of a clean cut as possible on all edges of the foam pieces that I was removing.  While micro would fill in any rough areas, I wanted as little micro as possible in these joints to minimize weight.  Besides just being a royal PITA and adding time to the build, the very real downside to this repair was that it was going to add weight.  Of course, any added and unnecessary weight is just not good.

Lower fuselage repair

After I cut the damaged foam areas out, the next thing on the to-do list was removing the damaged triangular longerons.  As I said before, I had to take a good look at this and really evaluate the best spots to tie in the new longeron pieces so that I maintain the original curve of the fuselage as best possible.

Lower fuselage repair

After I figured out the dimensions and locations of both the foam repair insert pieces and the triangular longeron repair pieces, I needed to clean up the fuselage side of all the surfaces and edges that would get the new repair inserts attached to them.

Lower fuselage repair

For the wood remnants leftover on the fuselage side walls, I started with a chisel, and then sanded the remainder away.  The foam wasn’t difficult to work at all, just a few swipes with the sanding block and a look to make sure the inside corners were square.

Lower fuselage repair

Once the surface was cleaned up, I started measuring the foam insert pieces to get a snug fit.  I didn’t want them too short, since just a hair “too long” of an insert might help a bit to keep the curve of the fuselage.

Once the foam inserts were cut to size, it was time to start microing them in place.

Before I could actually start microing the foam pieces into place, however, I needed to take care of one more piece of business.  Not only did the movers damage the lower fuselage sidewalls and triangular stringers, but they cracked the foam and slightly creased the fiberglass going up almost to the top longeron about halfway between the front seat and the instrument panel on the left fuselage wall.  I would have to repair this first before I could micro in the foam repair pieces.

Fuselage side crack repairFuselage side crack repairFuselage side crack repair

 

 

 

 

 

 

 

Fuselage side crack repair 

 

I let the micro repair to the crack in fuselage side wall cure for the night and planned to start on the foam inserts the following day.

 

 

•••

14 May 2012 — Now that the fuselage side crack is repaired and the micro has cured, it’s time to move onto inserting the foam pieces to repair the fuselage side walls.

Microing foam repair inserts

The first step in all this is to PROTECT the foam!  From what?  You may ask.  Well, both micro and flox are wonderful stuff, as is their base component: epoxy.  But all of this stuff should be minimized on any bare foam pieces that will later be glassed.  Layups are finicky endeavors and fiberglass likes sticking to fresh, clean stuff… not old nasty crusty dried up micro, flox or epoxy.  So, to protect the surfaces we tape right along the edge of the foam on each side of the micro seam.  From there on, we just need to ensure we try to not ding or crush the foam, although dings are easily remedied with?  Yes, Micro!

To ensure that the inserted foam lines up evenly with the existing fuselage sidewall, popsicle sticks are placed every few inches to keep the surfaces on each side of the micro junction even.

Microing foam repair inserts

Once the micro is lathered onto each side of the foam pieces being joined (in a manner very close to using wood glue to join two pieces of wood), the pieces are simply placed together and then firmly held in place (clamps, weights, hand pressure).  Any excess micro is quickly removed so as to minimize contamination on the yet-to-be-glassed foam surfaces.

I like to clean up the seam of the two foam pieces being joined by using the rounded part of a small popsicle stick so that there’s a slight depression, or trough, along the entire joint. That way when it gets glassed later on, there’s no rough lines of micro protruding above the level of the foam.

Note:  Micro dries very hard.  It can be sanded, but sanding can be a little dicy if it’s that close to the foam surface, since the foam surface would most likely get damaged, and need filled in with . . . ?  Yes! Fresh micro immediately before the next layup.  As you can see, much of the game in composites is trying to always think ahead and prep for that next layup that will take place on the piece you’re currently working on.

Microing foam repair inserts

Notice in this pic above that I keep pressure on both ends to ensure the micro will cure that foam joint nice and even (there’s tape under the clamp feet so they don’t get micro’d to the joints).  Also, notice the clamp on the inside of the fuselage—midway between the two outer clamps—providing outward pressure so that the foam insert here will cure in as close to it’s final curved position as possible.

•••

15 May 2012 — Today I took all the Frankenstein accoutrements off the fuselage (for you lesser-refined non-French speaking folk, that would mean clamps, tape, popsicle sticks, etc. Ha! ).

Cleaning up the seams and the micro doesn’t seam like it should take that long, but this took a few hours to get it back into decent shape for eventual glassing on the surface.  Also, remember that although the pics show the outside of the fuselage, the same amount of work (or more!) has to be completed on the inside.  Still, the right side lower foam is looking pretty good now and I’m please with the outcome.

Right fuselage foam repairRight fuselage foam repairThe micro looks nice, not too much contamination or ridges along the seams.

Right fuselage foam repairRight fuselage foam repairWhat’s not shown in these pics is the reshaping of the channel-style depression I had running pretty much the length of the lower fuselage to mount the cables and/or fuel lines into.  I didn’t cut the whole channel again, I just shaped a little entrance ramp/divot so that it can flow around the front seat bulkhead.  It should make more sense when I take pictures of it tomorrow.

After these pics were taken, I prepped two separate “pre-preg” setups with 2-plies UNI at opposing 30° angles, just like the original skin.  I laid those up then peel-plied them so they’ll cure overnight.

•••

16 May 2012 — I trimmed and prepped the damage area at the lower left side of the fuselage.  Note the line straight down from the middle of the foam insert piece: this is where the fuselage was cracked and was the first thing that I repaired.  Now you can see why, since the fuselage side had to serve as a support element to keep the new insert aligned and true.

Lower left fuselage repair

I micro’d the foam repair insert into place at the foam-to-foam junctions, but where the fuselage bulkheads are located that abut the new foam inserts, I actually used flox for more structural oomph.  I actually did that on the right side as well, I just failed to mention it before.

Lower right fuselage repairLower right fuselage repair

 

 

 

 

 

 

Below is the finished product as far as the foam and glass repair go for the right side.  For structural integrity for an overlapping glass bond, the general rule is at least an inch of glass overlap onto existing glass will give you plenty of strength.  You can see the entrance ramp channels I made at the end of the foam pieces to continue the continuity of the channel.

Right side lower fuselage

A couple of things that might pop out here.  First of all with MGS epoxy systems it’s sometimes difficult to see in pictures that there are actually layers of fiberglass on top of the foam.  Other epoxies get very opaque very quickly, and after around 2-plies the markings that may have been drawn on the foam start disappearing fast.  Not so with MGS… you can see fine lines through 9-plies and often even after 15-plies!  It’s just a very clear epoxy.  Also of note: you may have noticed a distinct color difference between the new inserted foam repair pieces and the ‘older’ fuselage, but Aahh, it’s not the age that makes up the difference in color, it’s the switch between the MGS 335 system (greenish in color) and the new-for-me system, MGS 285 (blue in color).  These colors are driven by the color of their hardeners:  MGS 335 has a green hardener, whereas MGS 285 has a cobalt blue color hardener.

Lower right fuselage repair

Finally, once the peel ply was removed, it left a very nice surface for both the lower triangular longerons to get floxed to; any subsequent glassing that needs to be done; and a nice, barely noticeable transition between the old and new glass surfaces.

Late in the evening after the micro cured on the foam insert repair piece for the lower left fuselage, I removed the tape, and any “dead” micro and prepped the micro joint for glassing.

•••

17 May 2012 — With the the left side foam prepped for glassing last night, I did a quick crosscheck and cleaned up a few minor rough spots.  I made a 2-ply UNI layup employing the “Poor Man’s Pre-preg” technique.  With plastic sandwiching my 2-plies of UNI glass I would be able to drive out more excess epoxy and easily cut the layup into the shape I needed, which was a somewhat inverted “T” shape… a “T” due to the repaired crack going up the outside of the left side fuselage wall and the subsequent slight “creasing” of the inside fuselage wall glass (running nearly entirely from the top of the fuselage down to the bottom edge).

Lower Left Fuselage Glass Repair Left-side Fuselage Repair

 

 

 

 

 

Before actually laying my 2-ply UNI pre-preg setup, I refloxed any seams and edges on the front seat & instrument panel to fuselage junctions.  I laid up the 2-plies of UNI (crosshatched at opposite 30° angles just like the original layup) and then peel-plied the entire layup.

Having prepped last night, including cutting the UNI cloth (I used scrap pieces left over from previous layups), I was able to lay up this glass over lunch so that it would cure enough by evening to be ready to remount the lower triangular longerons.

Once the left side 2-ply UNI layup was cured, I cleaned up the edges of the layup and ensured it was good to go for mounting the lower triangular longerons (or stringers).  I measured, trimmed, sanded and fitted the triangular stringers for each side of the fuselage.  I made sure the new stringers were aligned with and followed the contour of the bottom edge of the fuselage and clamped them in place.  Then, just like for the original mounting, I drilled 4 nail holes through the stringers and fuselage below to ensure the stringers would stay in their respective positions & be correctly aligned.

Lower fuselage stringer reattachLower fuselage triangular Spruce pieces floxed in

 

 

 

 

 

 

After I test fitted the triangular stringers I mixed up a batch of flox and then floxed, nailed (aligned) and clamped the stringers to the fuselage side walls.  The floxing included the area between the front seat corner and the stringer, and the areas where the stringers abutted the instrument panel as well.  Note in some of these pics you can see that I used a center clamp as an expander to push the fuselage walls out in order to help maintain the original curvature and shape of the fuselage.

Lower fuselage new triangular stringer installedLower fuselage stringer repair

 

 

 

 

 

 

 

 

•••

18 May 2012 — FUSELAGE IS REPAIRED!!! YEAH!!

Whew!  I removed the clamps and nails from the triangular stringers and ALL LOOKS GOOD!  Again, the fuselage is repaired and I can move on!

Fuselage Repaired!

Fuselage Repaired!

 

 

 

 

 

 

The side panels looked good & everything appears nice and strong!

The curvature of fuselage sides looks good.  There’s just a faint bit of a flat spot on the right side fuselage, but nothing to warrant concern.

Right Side Fuselage Repaired

Left Side Fuselage Repaired

 

 

 

 

 

 

But . . .

There ain’t no rest for the wicked!!

So I cleaned up the work shop and prepped for knocking out (aka “fixing”) the fuselage bottom.

Chapter 6 Step 2 of 2 – Building & Installing Fuselage Bottom

If you remember back to my issues prior to leaving Virginia—during the glass layup of the fuselage bottom—you’ll remember that I had to rip the back half of the glass off.  What remained was a layer of epoxy and micro.  That epoxy and micro is now in a state that I call “dead epoxy” and “dead micro.”  It’s there and present, but it ain’t doing anything for you (or me actually).  So in order to make a fresh layup of glass I need to remove all that epoxy and micro down to fresh foam.  This actually equates to a thickness around maybe .05″ on average, and maybe just a couple places just under 1/10th of an inch.  But for the most part, not very thick.  My tool of choice?  I choose Dremel.  It might take a while, but it’s got to be done!

So tonight, fresh of the victory of getting the fuselage back on line, I’m going to try to get a chunk of this back half of the fuselage bottom knocked out.

•••

19 May 2012 — Well, another repair in the making.  Which leads me to somewhat of a philosophical observation that I made to my buddy Marco one day:

Building an experimental airplane is really nothing more than having the wherewithal to continuously fix all the mistakes you make as you build it.

With that point in mind, I spent the entire evening hunched over the back half of the fuselage bottom, sanding off all the dead micro & epoxy.  I’ve got to get to that fresh foam before I can reglass the back half of the fuselage. [Uh, so I got a little carried away last night after the fuselage repair was finished and I failed to take any “before” pics of the back end of the fuselage bottom.]

Repairing Fuselage Bottom

Repairing Fuselage Bottom

 

 

 

 

 

 

After I got the back half of the fuselage bottom down to foam, I evaluated the front half of the fuselage bottom surface.  Not nearly as good as I had hoped . . .  that botched vacuum bagging effort really took its toll on this layup.  There were a few distinct areas on the front half of the fuselage bottom that were grossly delaminated.  In the areas of smaller air pockets I simply drilled holes and injected the delams with epoxy via syringe.  The larger delaminated areas I ground out the dead glass and will add an extra ply of glass overlapping about 1″ onto the good skin of the fuselage bottom layup.  It will add a little extra weight, but there is definitely enough good fiberglass on the surface to negate grinding off all that glass down to foam to reskin.  I’ll live with the little bit of added weight.

I guess it’s all part of paying the piper in the game of homebuilt airplanes.

•••

20 May 2012 — In transit from Virginia to Germany, the fuselage bottom had separated a bit from the 1/4″ plywood sled to which I had it attached.  The sled held the shape of the fuselage bottom to that of the shape of the bottom contour of the sides of the fuselage.  Since I would have to remount the fuselage bottom to its sled so it would be shaped correctly, it follows that I would have to remove it first.  So that’s exactly what I did.  However . . .

Foam forcefully extracted from fuselage bottom

When I pulled the fuselage bottom off of the sled (it took a lot of convincing!) about a 2″ x 3″ sized chunk of foam ripped off of the bottom side of the fuselage and remained on the sled.  This foam came off the fuselage right under the pilot’s seat pan where the foam is at one of its thinnest points.  It looks as though a fair amount of epoxy soaked through the foam, maybe through a hole, and bonded the foam to the plywood sled underneath.  I tried to pull the foam off and reuse it to plug the divot, but it wasn’t coming off without a fight.  So I simply cut the hole rectangular and made the same shaped plug to fill it.

Repairing divot in fuselage bottom

Repairing divot in fuselage bottom

Repairing divot in fuselage bottom

 

 

Once I had shaped the plug to fit the now rectangular divot, I prepped the glass by removing as much of the dead foam, epoxy and micro that I could.  I then sanded the showing fiberglass, taking care not to damage the edge of the foam.

 

 

Now that the fiberglass was crud-free, I whipped up a batch of micro with just a little flox to add some strength since it’s at such a thin spot of the fuselage.  I lathered up both sides with the micro and set the plug in the hole, carefully removing the excess micro that was squeezing out of the seams.

Fuselage bottom divot patch micro'd in place

Weighing down plug

 

 

 

 

 

 

 

 

After it was set fairly good, I added some weight to compress the plug, drive out excess micro and get as lightweight of a repair as possible.

Divot & delam repair - fuselage bottom

As I mentioned before, micro cures to a bright white.  Thus, when you look at the repair from the inside of the fuselage bottom, you can see quite a bright rectangular patch of micro.  You can also see where I cut out the multiple areas of delaminated glass.  I also thoroughly sanded the entire front glassed area of the fuselage bottom.  This will all eventually get covered with more glass to repair, then even another ply or two added over the entire front and back ends (inside) of the fuselage bottom.

After the plug dried and I performed another round of epoxy injections using a syringe into some small air pockets, I taped the fuselage back down to the sled and prepped the back half of the fuselage bottom for its second “initial” layup!

•••

The journey of a thousand miles begins with one step . . .

AND:

How do you eat an elephant?  One bite at a time!  Right?!

21 May 2012 — So you can call me chicken but I’m not taking any (more) chances with this fuselage bottom!  I’m going to glass it step-by-step, and make sure I concentrate on each area. With these deep funky crevices that I have to glass down into, I want to ensure I can fully focus on smaller sections of glass.  [I double checked my measurements for all my fuselage bottom divots against the plans, and they were all pretty darn close… In case you were wondering!]

Since I now have my fuselage “HOLE” repaired on the outside of the fuselage bottom, I’m ready to glass.  The bottom fuselage foam is 1-3/4″ thick and I have to make it curve sharply downwards at around 8″ from the back edge, thus curving it sharply upwards from that 8″ point to the back edge.  I don’t really like doing this because it has the potential to jack up the glass immediately under the clamps, but my plan is that I’m going to layup the glass and then clamp the edges at the apex of the curve to drive this fuselage down into the sled and have it cure with the nice curve it needs to follow the bottom contour of the fuselage.

Chapter 6 - Glassing rear seat areaI laid up 2-plies of BID on/in the back seat area up to the first “cross-hump” around 18″ from the rear of the fuselage bottom.   As you can see, I clamped the rear of the fuselage bottom with one clamp on the midsection of the rear seat on each side.

Chapter 6 - Glassing Back Seat

I then continued my glassing endeavors by laying up 1-ply of BID onto the 3 areas where I removed the delaminated glass from, at the front half of the fuselage bottom.  The majority of these delaminated areas are near the front seat hump and go into the left-side “map box” as well.

Patching fuselage bottom delams

After the glass was down and set, I peel plied all the layups.

•••

22 May 2012 — I cut the first ply (1 whole piece) of BID for the GIB (“Guy or Gal In Back”… the rear passenger, but the slang is “GIB,” so ya better get used to the idear, see!?) floor just forward of the rear seat ‘pan’ I glassed last night. I also cut the second ply (2 pieces) that would be used later for the entire back half of the fuselage floor. And since I was cutting glass, I cut 3 more separate pieces for more delam repair layups on the front half floor.

Glassing Rear PAX's FloorI glassed the first layer of BID on the GIB floor area as well as laying up glass for the remaining delams: the rear incline of the front seat divot, and two spots at the very forward edge of the fuselage floor.  Once all the glass looked good and excess epoxy was squeegeed out, I finished all the individual layups with peel ply.

Chap 6 - Fuselage Bottom Glassing/Repair

Chap 6 - Fuselage Bottom/Front Edge Repair

 

 

 

 

 

 

 

 

•••

23 May 2012 — Unfortunately I don’t have any pictures on this post.  (READ: For historical purposes and might make for some dry reading!)

I micro’d and then glassed the front right-hand corner ding (it was a little crunched from the move) and 2 side delaminations that measured around 1/2″ x 2-1/2″.

I glassed 2 separate pieces of 1-ply BID as a second layer between the FRONT of the rear (GIB) seat and the front (pilot) seat, overlapping by about 4″ onto the raised center part of the floor (i.e. middle of fuselage floor).  I then glassed 1-ply BID from the rear seat trough to the front edge of the front seat, which constituted the second ply in a 2-ply BID layup.  The first ply being the first layup above made up of 2 pieces, then covered by the second ply, made up of one piece and overlapping the edges of the first ply just a bit.

Finally, I used 2 pieces of BID overlapped by about 1-1/2″ at a 45° angle to the side of the fuselage bottom.  This  45° seam cut right through where the front seat back would touch the fuselage bottom.

I then peel plied all the layups.

•••

24 May 2012 — I removed the peel ply from last night’s layups.  If you’ve never seen fiberglass after peel ply is removed, it can often leave some ridges and strings along the edges of the laid up peel ply.  That is why I usually try to use as large of a single piece as possible for whatever I’m peel-plying to eliminate all the strings and funky edges.  Thus, I took about an hour to clean up all the peel ply “gifts” leftover from the layups.

Chap 6 - Glassing fuselage bottomAfter all the peel ply crud was cleaned up, I used 4 scrap pieces for the final 1-ply BID layup to the front 4 compartments of the fuselage bottom.

Chapter 6 - Glassing fuselage bottom

Chapter 6 - Glassing Fuselage Bottom

I used 4 separate pieces for this final layup for a couple of reasons.  First, a decent amount of the overlap will be removed when the center pineapple-shaped piece, which makes up the nose gear wheel well, gets removed.  Also, since there was some delams in that area, I don’t mind a few extra overlaps since in essence there will be 2-plies of BID where the glass plies overlap versus only 1-ply, which should help buttress up those delam areas just a bit.

Glassing fuselage bottom

•••

25 May 2012 — I removed the peel ply from the fuselage bottom final layups.  Since I laid up the front just a tad more wet than I normally would (just a bit!), I sanded it heavily to remove any excess epoxy & rough spots, and smooth out any of the glass transition edges.

Chapter 6 - Fuselage Nose Gear Well

I cut around the edge of the nose wheel well outline with the Dremel tool, exposing the duct tape underneath after I pulled off the glass piece.  BTW, this isn’t per plans.  The plans say to cut out the wheel well area first, then lay up the fuselage bottom glass to the edge of the cutout.  I thought it seemed easier to do what’s done in Chapter 7 with the landing brake, by just laying down a layer of duct tape.  Once I did that, then I didn’t have to concern myself with another edge,  I simply just glassed the area as a normal layup.

After I removed the glass overlaying the nose wheel well area, I then spent about an hour clamping the front of the fuselage to ensure the entire fuselage was straight.  For some reason my F28 bulkhead was almost .2″ off center and the instrument panel was about .07″ off center as well.  So I had to put expanders in to push them over to center before the fuselage bottom was flox-mounted to the fuselage sides.

After the F22 and instrument panel bulkheads were measuring straight, I whipped up a bunch of flox and mounted the fuselage bottom to the fuselage sides…. FINALLY!!

Straightening F22 bulkhead

Once again, to minimize excess flox weight and to get as tight of a bond as possible, I weighed down the fuselage bottom. By the time I was finished, I had piled up over 655 pounds on the top (technically the bottom) of the newly assembled fuselage!

Fuselage bottom attached to fuselage sides

Closing out fuselage - fuselage bottom attached

•••

26 May 2012 — After the bottom cured I noticed that there was a very thin gap between the fuselage bottom foam (at the very front edge) and the aft edge of F22 bulkhead.  This was caused by me centering the foam and compromising between getting the foam acceptably placed & centered on the bulkheads and sides, and getting the front edge of the fuselage bottom to make contact (or as close to contact) to F22 as best possible.  This small gap, about 1/32″ on the left side to almost an 1/8″ on right side, was in part caused by the nose being slightly askew, and the more extreme curvature (football shape) of my fuselage.

On a normal fuselage, F22 sits a lot more square (perpendicular) to the fuselage sides; whereas on my build, the foam sides needed to be beveled to an angle for F22 to sit (or mount) to them squarely.  In retrospect, mine weren’t beveled nearly enough to keep F22 mounted straight across the front.  Since the fuselage sides were beveled/angled (by virtue of them being pulled inwards so much), it created a very slight inward bow of F22 at its midpoint/centerline.

Chap 6 - Fuselage bottom attached to sidesI sanded a thin wedge of foam, and micro’d it to the fuselage bottom foam on one side and floxed it to the aft bottom face of F22.   I then clamped F22 tight against the foam wedge insert and the fuselage bottom’s front edge.  I also added some flox into some very minor gaps between F22 and the bottom triangular longerons.

Chap 6.2 - Fuselage Bottom Attached

I took a couple shots of some of the 655+ lbs in weights that were piled up on top of the fuselage.  To think that the fuselage components now are essentially foam with a couple plies of glass on ONE side of each foam piece, GLUED together… without even the outside sides glassed!  Wow!  This is some pretty STRONG stuff!

Chap 6 - Weights used on fuselage bottom

Once the flox holding the fuselage bottom to the sides and bulkhead cured fully (I cleaned all the excess flox off all the joints), it was time to actually connect the bottom to the sides and bulkheads with fiberglass.  I would employ the “Poor Man’s” pre-preg method with 1-ply of BID, as called for by the plans.  Note:  When laying up epoxy in an inside corner, one must use a flox fillet (like how you would apply caulking in a corner) so that the glass curves around the inside corner on a radius, and doesn’t have its fibers jammed into a 90° corner.  A fillet allows the natural strength of the fibers to flow undisrupted (ie not crushed).

I laid up the pre-preg using a few BID scraps.  Remember, a 1″ overlap provides plenty of glass tensile strength in a layup.  I then sandwiched the BID between two pieces of plastic, wet out the BID with epoxy, and then squeegeed all the excess epoxy out.  I could then draw out my BID tapes with a Sharpie, and annotate the description of each one.

Of course I sketched this all out beforehand so I had a good idea of the size of the pre-preg setup I needed.  And once I drew out all the lines, I simply cut the pre-preg with scissors to get the individual 1-ply BID glass tapes that were used in the corner junctions between the fuselage bottom and the fuselage sides & bulkheads.

Chap 6 - 1-ply BID tapes for fuselage bottom to sides

Ch. 6 - 1-ply BID pre-preg for fuselage bottom to sides

After I laid up all the glass pre-pregged tapes, I went around with my peel ply “tapes” and covered the corner glass with a layer of peel ply so that all the BID tape corner layups would have nice smooth edges and clean glass transitions.

Ch 6 - Fuselage sides/bulkheads glassed to bottom

As per plans, I also filleted in a flox joint between the bottom of the fuselage and the very bottom aft edge of the front seat bulkhead.

Chap 6 - Fuselage sides glassed to bottomChap 6 - Fuselage sides glassed to bottom

 

From the pics you can see that essentially the entire triangular longerons—which now make up almost a beveled curve in the bottom left and right interior corners of the fuselage—are covered with fiberglass that overlaps onto each side to connect the fuselage bottom, to the longeron, to the side.  These BID tapes make for some very strong joints.

Chap 6 - Fuselage sides glassed to bottom

•••

Recent Posts

Project Update

Hey Guys,

I left my last project update for a while so everyone would have a good chance to read it.  

So this is it folks!  I hope for this to be the final push from now until Rough River to get the main assembly of the aircraft completed.  That’s my goal.  Is it an aggressive timeline?!  Oh, yeah!  After Rough River, I then expect the next few months to be finalizing any leftover punch list items and the finishing & painting! 

Over the past few months I’ve had some unexpected scope creep in my build, which is all well and good because the build is THE project.  As you know I rewickered Marc Zeitlin’s new AEX system which took a fair amount of time to implement, then I had planned on knocking out a good dozen electrical related items so that I could close up the nose.  I got a bunch of those completed, but kept finding myself not being able to really close out wire runs, confirm install spacing configurations such as the pitch trim unit, etc. because I couldn’t sit in the airplane and confirm what I had dimensionally without the actual pilot’s seat in place.

This drove me to move my immediate project line of demarcation from the instrument panel, back one more bulkhead to the pilot’s seat.  I was then going to knock out the pilot’s seat area –including the thigh support & cover– but there was a glaring prerequisite to doing so: I couldn’t get the pilot’s thigh support configured & installed without the fuel lines in place!  Thus, I needed to move the project line of demarcation back one more bulkhead and knock out the thigh support sump tank to get the fuel lines run in reality without merely estimating some more with a fake, mocked up install.  

So the immediate order of battle right now is to finish the fuel sump (including configuring the majority of the back seat area), and then the pilot’s seat area. These, in turn, will allow me to finalize the configuration of the nose components. At which point I will focus on the building the nose while concurrently finalizing the wheel pants install (nope, haven’t forgot about those!). Then the canopy install will be after that.

Hang on to your hats folks, it’s about to get busy all up in here!

Cheers!

 

  1. Chapter 21/22 – Sump glassing done! Leave a reply
  2. Chapter 18/21/22 – Atonement! Leave a reply
  3. Chapter 16/22 – The Cobra strikes! Leave a reply
  4. Chapter 21 – Sump tank complete! Leave a reply
  5. Chapter 21 – Sump tank top mounted Leave a reply
  6. Chapter 21/22 – GIB area stuff Leave a reply
  7. Chapter 21 – Fuel sump top GLASSED! Leave a reply
  8. Chapter 21 – Sump top glassed Leave a reply
  9. Chapter 21 – Interior layup cleanup Leave a reply