I should note starting off that it took me a bit of research and thought yesterday to figure out that I needed what was essentially an interior “wall” to retain the wet flox & BID that goes into all the component hard points on the canopy frame.  Thus the reason for a layup of 2-3 plies of BID –above and beyond the normal layup schedule– at each hardpoint location.

I started off today with another long round of more refined clean up of the canopy frame.  I Dremelled off a lot of dead micro, and also Dremelled a small trench around the front edge of the canopy about a foot in each direction from CL.  Like the top side per plans, I’ll also lay up the first ply with the glass going into this trench and fill it with flox.

I then got to prepping the right front hinge location for a retainer layup, as I mention above. The plans denote a 1.5″ thick (over normal width longerons… more on that below) canopy frame where it contacts the longerons, but since my canopy rail matches the thickness of the longeron (~0.8″) on the front half, I needed to ensure I maintain (or make) my hard points at the 1.5″ width.  As it goes, at the front end of my canopy frame it’s not difficult to obtain or keep the 1.5″ width for the hard points.

But I digress, back on the front hinge hard points, I used micro on the areas that would not get dug out and then placed raw epoxy and then a patch of peel ply over each actual hard point spot.

I then laid up my prepregged 2 plies of BID over the hard points, and then peel plied that since the final interior canopy frame layup will cover this glass.

I then taped off the back right half of the canopy along the “glass-to” line that matches the exterior glass line of the canopy.  I then sanded the bare canopy edge to give it texture to grip the interior glass when it’s laid up.

Since I don’t have 1.5″ of foam frame here, I manufactured it by shaping a piece of foam that will get micro’d to the existing foam rail.  I made it “L” shaped so that it also rests on the bottom half of the exposed canopy edge, with plenty of room for glass above it.

I then micro’d the additional foam piece in place that then gave me 1.5″ wide on the canopy rail right at the right side canopy aft hinge hard points.  The foam piece extends 1″ beyond the hardpoint segment forward & aft to allow for a transition back to the existing narrower canopy frame.

I then made up another piece, only for one hardpoint, on the other side for the #3 of 4 canopy latch.

[NOTE:  I’m going with 4 canopy latches.  Here’s why:  My canopy goes much further aft than plans, plus I have a longer aft canopy frame.  In addition to that little factoid, I don’t have a good option for keeping/incorporating the middle latch in the same place due to my roll bar frame.  If I move the middle latch forward 2″ than I can just barely clear the frame, but since I have the entire kit from Jack Wilhemson, pre-made, then I only have enough of the long rod (tube) that then forces me to move the aft latch forward about the same as the middle latch.  So, I have much more canopy + frame aft, but then I’d be moving my aft latch forward a minimum of 2″.  I don’t much care to do that.  I’d rather move the aft latch back an inch, move my middle latch forward 2″ and then fill that gap in with another latch.  With a MUCH bigger canopy than stock I think I wouldn’t mind having one more securing latch anyway!]

Here’s the foam piece micro’d in place for the #3 of 4 canopy latch, that will be located just aft of the roll bar frame.

I then cut another piece of foam (quickly, since I had leftover micro) and clamped it in place on the left side aft canopy frame.  This foam piece will of course make up the left aft canopy latch hardpoint.

So, here are the foam pieces (incorrect width! more on that below…) for the aft 2 canopy latches, secured in place with clamps while the micro cures.

And a bit a later after the micro cured…. look nice eh?  But again, wrong width!

My mindset the whole day had been geared towards the aft hinge hardpoint, which, no matter what size the longeron is needs to be 1.5″ minimum width to have a good foundation for mounting the hinges to.

With that in mind, I got busy shaping/curving the top side of the added foam so it made a nice transition into the canopy edge.

I prepped it in the same fashion as the front hinge hard points and as I was finishing up the 3 ply BID layup I was thinking about my next task: glassing the 2 hardpoint retaining layups on the other side…. I then had a DOH! moment.

As I mentioned, no matter what size the longerons are, the 1.5″ wide hardpoint works fine for the hinge hard points, but that is not the case with the canopy latch hard points, which MUST overhang the longeron inboard since the latch assemblies attach inboard of the longeron.  Remember, from the pilot’s seat aft my longerons are a hair over 1″ wide, so a 1.5″ wide hardpoint works for a 0.7″ wide longeron, but not a 1″ wide longeron.  Ugh!  The good news is that I caught my error before I glassed in the retaining layups at these hard points.

Again, having some left over micro, I quickly made up 2 more additions to bring the canopy frame inboard a minimum of 0.35″ to allow enough hardpoint for the latch assembly to attach to.  The foam pieces are a bit thicker than required, but of course I’ll just sand them down to the proper thickness before glassing the retaining layups.

I then got busy digging out the foam and removing the inboard peel ply off the 3 left side forward hardpoints . . .

And the two forward right side hinge hard points.

BTW, although these layups were fairly fresh and I used NO micro on the foam surface where I applied the peel ply, it was still amazingly difficult to remove…. each hardpoint took a good 10 minutes in just removing the peel ply!

About this time in the evening is when everything turned magical, and by magical, I mean it went south ….. a bit.  Kinda weird and still assessing!

I started off by rereading the plans and then proceeded to glass in the 3 hard points along the front left side canopy frame.  I knew from accounts from other builders that 15 plies in these hard points, especially the deeper ones I had, was simply a fantasy and that it required a whole lot more than that.  I gathered up all my BID scraps, whipped up some flox using my “slow” hardener (75/25 slow/fast) to a point where it was right at the cusp of being wet flox (i.e. towards the thicker side of wet flox), and got to work.

Ok, first off, my bad for not taking into account the heat in my shop.  It was HOT outside and well over 80° F in my shop.  Secondly, I had never encountered an issue with a large scale exotherm type event with anything other than using fast hardener.  IIRC, in Germany I had an exotherm with a huge cup of epoxy when I left it sitting there for a good while when I was doing something really big like the wings or fuselage, and one event when I used fast hardener for the filling in the one of the elevator hinges . . . which resulted in it spitting the flox right out of the hole.

But just as I was a few plies from finishing up these holes, I started to see some bubbling around the edges of each hole.  I felt the sides of the retaining glass and it was hot, so I grabbed my thermometer.  I got one reading at 201° F for a blip, but couldn’t replicate it. Most of the readings on all the surfaces on or around the hardpoint layups were in the range 160-195° F.

I had a couple of small leaks around the retaining glass layups going on which had annoyed me since I had to keep wiping up epoxy running down the inside of the canopy (one of the few times I’ve used paper vs plastic, and I got a fair bit of epoxy running down the paper!)…. however, I think these leak areas worked to allow the heat to vent and the layups to stay in place with no expulsion action going on.  I continued to monitor the temps as there was no discoloration of glass on the top side of the canopy frame and no melting foam anywhere.

Out of curiosity I tried to add a bit of flox to the top side of each layup just to use it up and get the final 0.2″ of fill on each hole.  However, when the flox hit the bubbling brew on each hole it just burned out immediately and turned white (as you can see in the pics below).

The layups stayed warm for quite a while, but again, except for one non-repeatable blip just over 200°, I never saw any dangerous temps.  I’ll cut a core out of one of the hard points to see if it is solid [it should be, it was filled with glass] and check to see if the epoxy/flox just cured overly fast or if it burned out.

Having learned my lesson, I then grabbed a can of straight SLOW hardener and got to work on the right front hinge hard points.  Note the duct tape on the front hardpoint… this tape plays a key role in the next part of my story.

You see, as I was filling up the 2 front hinge hard points, I thought to myself the front hard point must be bigger than the back one, because the back one is filling up noticeably quicker with the same amount of flox and glass going in.  That’s when I realized the front hardpoint was leaking and thus harder to maintain the same level as the aft hardpoint.

Seeing that I wasn’t going to win this game, and almost out of flox in my cup, I simply cut a piece of peel ply for each hole and set the peel ply in place.  I would simple finish these holes with flox paste tomorrow and call it a day.  I did a final wipe down of all the epoxy that had run down into the canopy onto my thick brown paper, and knew I’d be back one more time for some cleaning before heading to bed.  And with that, I went upstairs and took a shower.

When I returned to clean up the epoxy mess caused by the leaking front hardpoint, what did I find?!  These hardpoint layups –with straight SLOW hardener– both had some minor bubbling going on around the edges!  I grabbed the IR thermometer again and checked temps (again!) and sure enough, same range as the left side: 160-195° F.  Highest temp I saw on this side was 198° . . .  amazing.  Again, no discolored or burned glass or foam anywhere, just a really hot curing layup. (sorry, no pic of this tonight but I’ll grab one for tomorrow’s post).

So, I cleaned up the epoxy, went upstairs to spend some time uploading the pics for this post and returned about 45 minutes later.  The temps were still fairly high, although significantly cooler (130-150° F), and the epoxy leak had stopped, so I did a final cleanup of the epoxy and pulled out the wet tape and paper from inside the canopy to ensure I had no curing flox or epoxy on the inside canopy surface…. thankfully it was really clean and nothing had really gotten onto the canopy.

Since the weather temps are high here and my canopy hard points are significantly deep, for the last 4 hard points I will fill them halfway and then peel ply the layup, and then finish it after it cures.  All I can say is wow.  I guess my technique of trying to follow the plans is more hazardous than stuffing the holes with BID and pouring wet flox in & around it!

All part of the struggle I guess of building these airplanes!

First off, I know I’m spending a number hours more per day than I had planned on this canopy… however, I both want to clean up what I consider a big SNAFU on my turtleback and get the canopy acceptably configured for transport.

Defining the turtleback issue:

In the pic below, note the 9 O’Clock bulge and the 1-2 O’clock deflation.  I think I unknowingly did this by forcing the canopy bottom corners both over to the right before placing the turtleback foam in place.  Actually, I did notice it, but I thought it was a very slight, minute shape shift. It just wasn’t obvious nor clear that it would become so obvious and prominent after shaping and glassing the turtleback.

I wanted you to see the pic below, with the turtleback unmarked and in its current “natural” state.

The turtleback shape mitigation plan:

Here is my analysis of how to minimize the misshapen turtleback, and as you can see in the pic below I’ve marked it up to explain my mitigation plan.

First off, let me reiterate and be clear that my plan is to MITIGATE this off-balanced issue as best possible.  I have NO illusions of completely eliminating it.  The only true fix would be to rip off the canopy and redo the whole thing, with my entire focus then being how to mitigate this configuration debacle on the aft end vs (again) eliminating it.  And of course risking the chance of screwing up the very nice outcome of the front 90% of the canopy!

Problem #1 is the bulge on the left side, denoted in the pic below with the red oval and the white star being the apex of the bulge.  Note how below the star the canopy is vertical to almost coming back inboard.  Contrast this with the other side (right) where it has a comparatively gentle sloping curve, much more constant in nature.  To be clear, the aft canopy edge drove the shape of the turtleback so the only thing further outboard than that canopy bulge on the right is the 3 plies of BID holding it in place.

The REASON this shapeshifting occurred was most likely my maniacal –and probably misplaced/misguided– adherence to keeping the center canopy elevation even with the upper engine cowling extended contour angle (denoted by the green arrow and line).  If I had adjusted the canopy and let the elevation of the top go where it wanted to naturally, I think I’d still be dealing with this configuration oddity, but just in a less severe form.

Yet another issue, that will actually help in the attempted remedy of this SNAFU, is that for some mysterious reason –despite many repeated measurements– the fore/aft vertical canopy line of the turtleback glass overlaying the aft edge of the canopy is 0.35″ aft on the right side than it is on the left… which I’ve denoted with the blue line.  This obviously means the left is more pronounced when looking at the turtleback from CL aft as in this pic because its termination line is 0.35″ forward than the right side.  Making the bulge even more pronounced!

My plan is a 2 step plan.  First is to fill in the area marked by the yellow dashed line with 1/4″ foam and shape it.  Focusing on trying to manufacture a right side apex (purple line) opposite the left one.  I will also very aggressively sand the left side along the apex line to knock that down as much as possible.  Even 0.020″ will make a difference.

Part of the deflation between the 12 O’clock and 3 O’Clock positions is that on the left side my sanded depression for the 3″ UNI tape was close to spot on and it was even with the other foam surface, whereas on the right I went just a hair deeper and the UNI tape is not proud nor even, and is ever so slightly sunken… but not enough to affect the glass transition with the overlying BID.  It just adds to the depressed/flat/deflated look on that right side.

Now, I say a 2 step plan due to the fact that I feel I can/should deal with the turtleback to canopy angle issue later, after I get the upper cowling in place.  However, IMO I need to see if this remedy for the right side will work effectively BEFORE I pull the canopy off to shape and glass the interior surfaces.  If it just doesn’t work, I may go further in my corrective actions.

One final thought on the remedy to my unsightly creation, which actually isn’t really a remedy but rather of byproduct of the shape and configuration of my plane’s major components.  The bulkiness, size and shape of the canopy does a good job of hiding this issue from the front.  It will most likely be more noticeable with the airplane in the grazing position because it naturally takes more of the canopy’s sheer size –that serves to block the turtleback from view– out of play.  The other saving grace for my surreptitious cover up here is that the cylinder humps on each side of the upper cowling serve to block the view of the lower half/third of each turtleback side when viewing it from the back side of the plane (determined by my holding the cowling in place and assessing the aft view with cowling in place).

Clearly what I’ve shown here in these 2 pics is NOT visible (to my knowledge) in any of the pics I’ve taken at other angles.  Since you can’t be on separate sides of the airplane at the same time, I think if I add mass to the right side and mitigate the off balance between the two sides it would be really hard to get a really good view of this abomination at any other angle other than straight forward or aft of the plane.

Finally, I’m not trying to hide bad workmanship and be done with it.  Clearly there are no structural issues at play here and it’s my belief that any airflow imbalance will be minimal.  But for the sake of getting this thing in the air, and also to not waste any more time, materials, or money, I want the best mitigation possible and point out the view-blocking components as a point of note.  No builder wants a glaring, non-structural issue being the focal point that eyes are drawn to on their creation as it sits on the ramp!

So I started today by trimming the overhanging cured glass from around the firewall.

Here’s a side shot of the overhanging glass over the firewall’s aft edge.

Here we have the glass trimmed away that was hanging over the firewall and also the 1/4″ thick Divinycell foam that I micro’d to the right side turtleback.

I then did an initial round of sanding on the added foam, as well as cleaned up some micro runs.

Here’s the 1/4″ thick added foam piece sanded and shaped down close to its final shape before glassing.

Here you can see that, although still not perfect, the addition of the foam has taken the shape & aft view of the turtleback from “Ooh, gross!” to “Hmm, it’s not horrible…”

I then micro’d the foam and glassed it with 2 plies of BID.  I used an extra ply to allow me to really hit it hard with a sanding block if need be when it comes time to finish the surface for paint… with the micro finish allowing me to further fine tune the turtleback’s shape and symmetry as well.

Here’s a shot of the shaped & glassed foam added to the right side of the turtleback

This pic shows the newly positioned line of the canopy to turtleback intersection.

Before I got busy sanding and shaping the added turtleback foam, I Fein saw cut the aft edges of the canopy at the longerons.  Here’s the left side, but I forgot to grab a shot of it on the right side before I reglassed the added foam piece.

I also took a few minutes to dig out the foam in the mouse holes on one of the 3 strake ribs that I left out of the last haul to NC.  I’ll try to knock these out as I go about my other build tasks so they’re ready when it comes time to build the strakes in the next 2-3 months.

I also took a little bit of time to take the long sanding board and really finalize the shape of both the flocro transition for the added Balsa wood strips on the aft nose cover, as well as the intersection of the “old” nose sidewalls and the new foam I just recently added to make up the forward nose sidewalls.

[I have some slight “shoulders” on the nose sides right where I added in the new PVC foam when creating the top nose structure.  I sanded these for a bit but I think I have to accept the fact that since I left my original nose sidewalls a bit high and with a vertical surface, that the nose then somewhat sharply transitions into the top curve… this makes for a somewhat abrupt change at the nose sides from curved (top) to vertical (side).  So although curved, it’s not as smooth as I would want.  A minor issue, as I think it has zero affect on nose structure strength or aerodynamics, and I suspect not highly noticeable when the nose is finished to paint.]

Here are some closer up shots of the flocro transitions between the edge of the added Balsa wood and the front/side areas of the aft nose cover.  To be clear, the height of the front edge of the balsa wood was about 1/32″ when I applied this flocro, so there is not a ton of added flocro added here.

Tomorrow I plan on actually cutting the turtleback to separate the aft canopy frame and then remove the canopy from the fuselage to begin canopy internal shaping & glassing.

I’m dealing with a repair issue on my truck that took up a number of hours both yesterday and today, so I didn’t get as much shop work in as I would have liked on the canopy today.  I did get a few hours in though.

I started by cutting the glare shield’s aft edge trim/seal to length.  I also tapered the ends so that it flows in nicely at the outboard edges.

[Note the very outboard edge of the glare shield that is situated immediately over the longeron, this is discussed below].

Here’s a shot of the right side cut/tapered aft edge trim/seal of the glare shield.

I then covered the trim/seal with painters tape to protect it from getting gummed up by the duct tape.

I then applied a couple layers of protective duct tape over the glare shield.  After I got the tape on I realized I hadn’t (re)trimmed the very outboard edges of the aft nose cover, along side the glare shield.  These ends are immediately over the longerons and for the canopy frame to be shaped properly they needed to be trimmed in width . . . or at least very close to their final width.

So I peeled back the tape on each side and, using the Fein saw, trimmed off about 0.1″ of the very outboard edge of the glare shield in between the taped in 1/8″ aluminum spacer for the canopy and the aft outboard edge of the Balsa wood on the aft nose cover (no pics on this trimming).

I then laid the tape back down in place.

A side shot of the taped up glare shield…. with the aft edge trim/seal in place.

I then spent about 45 minutes measuring and shaping a block of foam for the center section of the canopy front skirt.  I’ll get a shot of that tomorrow with the plan being to finish up the canopy skirt/frame foam, and then get the canopy frame shaped and glassed.