Chapter 25 – Wing bottom epoxy wipes

Today was all about getting the bottom of the wings epoxy wiped with pure West epoxy. I did do some minor tasks in between like remove the nose gear wheel well doors and strut in prep for sanding, priming and painting, but for the most part the entire day was focused on these epoxy wipes.

The first pair of pics of below are after the second of 5 wipes total.  The average cure time in between the wipes was 1.5 to 2 hours.  Albeit between the second and third wipe was over 3 hours.

It is quite interesting (IMO) that the first wipe took 3 pumps of West epoxy per wing for a total of 6 across both wings.  The second wipe took almost exactly half that with 1.5 pumps per wing, 3 total.  For wipes 3-5 we (Jessica helped me on the last few) used 1 pump of epoxy per wing.

These last 2 shots are of the wings with the 5 total wipes after they cured.

I have to say it’s pretty cool to see the wings looking shiny with epoxy and feel fairly slick and smooth when you run your hands across them.  Even the sound is a bit different if you tap the surface since these are now “hard shelled.”

With the wings epoxy wiped, tomorrow I plan on jumping back on to the aft fuselage and bottom cowling junction to finish that up as best possible.

Chapter 24/25 – Aft fuselage seam

Today was all about dialing in the shape on the aft fuselage at the junction with the bottom cowling, with almost the entire focal point being on the vertical sidewall.

I spent about 45 minutes per side sanding down and contouring the West 410 filler that I applied last night.

As I continuously note, this is definitely an iterative process.  I then sanded down the other side as well.

I also sanded down the interfacing areas on the side front edges of the bottom cowling as well.  I then worked both the bottom cowling “micro” fill and the aft fuselage “micro” fill together.

As I then did on the other side as well.

A point of note I’ll make about filling in the depression at this side wall area on each side, is that I wish I had had the foresight to recognize the real need for it and do it earlier (i.e. pre- armpit intake install) as it is clearly closing the gap between the fuselage/cowling sidewall and the armpit intake vertical side.  Where Mike Melvill’s cowling installation instructions say to mount the armpit intakes 3/4″ from the bottom of the strake on the horizontal side, and 3/4″ from the sidewall on the vertical edge, my gap now will be just over 1/2″ on the sidewall side… more like 9/16″ really.

However, do I think this will lessen the effectiveness or hamper the air entering smoothly into the armpit intake scoop?  No.  Especially since I don’t have external fuel sump blisters to disturb the air in any way before the air enters the armpit intakes.  This is  just a symmetrical, cosmetic issue really, but one I wanted to address.

There is still some filling and matching left to do… as there always seems to be.  I’d say I’m about 90% done on this filling task.  I did do another round of minor straight West 410 fill… which I didn’t grab any pics of.  I then left that to cure overnight.

I then got busy sanding down the inside bottom surfaces of the main gear.  The left gear leg is shown here.  I did the same on the right side.

I had pondered about slathering up these bottom surfaces with micro, but then decided to wait until the gear fairing at the intersection between the top of the gear and fuselage are completed and installed… then I’ll finish the inside bottom surface of the gear legs all in one fell swoop.

Tomorrow I plan on epoxy-wiping the bottom of the wings with 5 coats of raw West epoxy (“raw” as in only epoxy + hardener…. to be clear, not just resin) among other tasks, if possible.

Chapter 24/25 – All about the paint!

Starting out today was all about getting this silly paint stuff figured out.  Unless some real egregiousness rears its ugly head, I’ve got the paint system figured out: 2-part polyurethane yacht paint from Epifanes.  I went with the 2-part because unlike single part polyurethane the 2-part coats can be sanded and re-applied, pretty much like a standard type paint… not one coat and done like single part.  This means if you need to rework a composite area on the plane, touch-up, recoating and maintainability is not an issue.

The only real issue is availability…. the color on the left below is Capri Blue, the color on the right is Bright Blue.  Although I actually originally planned on a darker blue such as the Bright Blue on the right, which I love, I kept hearing the voice of Burt (and a few other builders!) cautioning me against going with a darker paint…. which I eventually relented to and set aside my rebel, rogue ways on this task.

The problem is that there is another blue, Bold Blue, that Epifanes makes (in theory) that is in between these colors in shade.  It’s just been unavailable for over 3 months!  To get some paint in hand I pulled the trigger on the darker blue, but over time realized it was just too dark in reality.  Then I got the light blue to test, and upon receiving it’s just too light for my taste.

What to do?

Well, I did a taste test of sorts with these colors. I still really love the dark blue, but again, I’m trying to be responsible here and mitigate as best possible any heat issues cropping up on the bird’s finish.

As you can see, I used the inside edge of the landing brake as a real world test canvas and applied the light blue along the left edge, the dark blue along the right edge, and a 50/50 mix of both (more along the lines of the Bold Blue that I wanted!) along the bottom edge.  Keep in mind this pic is right after I painted the edges . . .

Since the cured paint looks a tad bit darker as you can see on this test swatch I made with the excess paint from each application. I used a piece of black project cardboard to assess how each color would contrast with the black, which is one concern I had with the darker blue in that it might be so dark the black trim would be harder to see.

I want to keep my color scheme simple in the amount of colors I use. White flying surfaces and white base with a good bit of blue bordered by a black accent stripe.  No other colors involved.

My original color scheme was this… clearly I really like it.  But admittedly the blue is pretty dark.  I wouldn’t have any real concerns with using this darker blue except one main area: the canopy frame.  Since it is carved and constructed out of blue wing foam, I clearly don’t want it getting too hot and having the glass delam.

Thus I’m lightening up the blue paint in my scheme a couple of shades to avoid poking the bear… keep in mind I snagged a color match from the original test pic of the landing brake to create this pic below.  The actual blue color will probably be just a very tad bit darker than what we have here, once fully cured (see color swatch above).

One reason I started out the work day focusing on paint was that I new the folks I deal with have a few cans of Capri Blue on hand.  Almost literally nothing else is in stock.  So after I assessed the paint colors and decided to go with the 50/50 mix, later in the afternoon I pulled the trigger on another can of the Capri Blue… giving me 2 cans each of the light and dark blue paint.

Also, being Friday and a business day, it allowed me to get on the horn with the Epifanes folks and ask a bunch of questions before pressing forward in my upcoming paint adventures.

Back on the build… I then pulled the peel ply from the RAM air scoop EZ Point layups, used a small drill bit to remove the protective plastic inside the threads, and then carefully trimmed the glass away to expose the screw holes.  I then tested out a couple screws to ensure that the EZ Points were still fully operational… which they were.

I then spent a few hours sanding, tweaking and dialing in the aft fuselage sidewall interface with the bottom cowling.  So far the results look promising in removing a rather notable indentation at this junction.

Again I failed to get any pics (thought I had) of the results of the original sanding, but here is the subsequent round of “micro” fill that I applied to the aft fuselage.  I used straight West 410 filler here since I wanted to be able to sand down the edges —especially along the very front edge of the fill— to blend and fair in this fill with the previous fuselage fill.

I also added some of this straight West 410 to some spots on the front side edges of the bottom cowling as well.

With my latest round of “micro” finish applied to both the aft fuselage and the bottom cowling, I left it to cure overnight.

Chapter 24/25 – RAM scoop mounted

I started out this morning pulling all the weights off the RAM air scoop mounting flanges. The resulting pics show you the screws securing the flange to the bottom of the fuselage.

Grant it there is a longer section between these screws to the front center screw than I’d like there to be, but with the available real estate to mount into between these points being virtually non-existent, beggars can’t be choosers.

I then unscrewed the screws from the newly floxed-in EZ Points and all the other attaching screws and CAMLOCs from the RAM air scoop/hell hole hatch cover.

As a point of note I’ll again simply highlight the acceptable —but not the most desired— gap between this pair of EZ Point hardpoints and the center screw up front. But clearly I feel that the configuration and positioning of these attach points will hold this RAM air scoop in place on the bottom of the aircraft just fine…. lest I would not have proceeded in the fashion which I did!

I then got busy sanding down the area around the installed EZ Points, and a bit of the surface of the EZ Point locking nuts themselves to level it all out in prep for a ply of BID, to add yet another bit of strength to these RAM air scoop attach hardpoints.

After stuffing the threads with plastic Saran wrap, I then laid up a ply of BID over each EZ Point, and then peel plied the layups.

While the EZ Point layups cured, I then got busy on what I currently consider the long pole in the tent as far what is the priority to get knocked out on this build: the aft fuselage to bottom cowl interface surface leveling on each side.

I taped up the front edge of the bottom cowling on the vertical sides and a bit on the bottom right side to protect it from the “micro” finish that I was about to apply to the aft fuselage side of this intersection.

Which I did here.  I mixed up some West 410/micro fill and slathered it on both sides.

The “micro” wasn’t too dry, but it was dry enough that I needed to use my heated blades to get a good application.

I then left the latest addition of “micro” fill to cure overnight.

 

Chapter 24 – RAM scoop final install

After some researching, assessing, measuring and investigating I determined that just like the threaded phenolic CAMLOC receptacles (upper area in pic below) that I had to go down through the original bottom skin glass, I would have to do the same for this latest pair of threaded hardpoints for the RAM air scoop.

The difference here was that A) I had to drill through a ply of Kevlar (turned out not to be a big deal) and B) the area immediately “above” (below here since inverted) these EZ Point locking nuts were the respective thigh support sump tanks… so diligence and care in going down through the original skin was of upmost importance, lest I put a nice hole in one or both bottom(s) of the thigh support sump tank(s).

After ensuring my center hole was good, and no damage to the bottom surface of the thigh support sump tanks had occurred, I then marked the respective outline of each EZ Point locking nut before drilling a series of closely spaced small holes all around the marked radius.

I then used my Fein saw to cut out the exterior fuselage skin circles to inset the EZ Point locking nuts….

As you see them test fitted here.

I then taped up the bottom surface of the RAM air scoop mounting lips (each side) and bolted the EZ Points to the underside of these mounting flanges.  I then floxed the EZ Points into their respective fuselage-bottom divots and secured the RAM air scoop/hell hole hatch cover in place.

Moreover, to keep the RAM air scoop flanges —and thus the EZ Points themselves— pressed as firmly down in place as possible, I added a fair amount of weight on top of the RAM air scoop side mounting flanges.

Another shot of the weights to press the EZ Points firmly into place while curing.

With that, I left the newly installed EZ Point locking nut hard points to cure.

Chapter 25 – More bottom cowl seam

Today was another light build day, but I was able to get some stuff done.

First off, I’ve been doing some pondering and some thinking of just how I’m going to install the EZ Point hard points (10-32 versions that arrived) on the bottom of the fuselage for the last securing hard points that need to be installed for the RAM air scoop.

My pilot holes reveal that I don’t have enough depth so I may have to follow suite with the threaded phenolic CAMLOC receptacle hard points that I installed just aft of these. Meaning I’ll have to go a layer deeper into the original bottom skin of the fuselage.  I’ll assess this a bit more before I decide on any specific course of action.

Back on the bottom cowling . . . after the initial sanding and shaping (separate action from the cheese-grating btw) I determined that I was in need of another round of “micro” fill before I remounted the bottom cowling onto the airplane —to “build” the other, fuselage side up to mitigate the significant side depressions at the bottom cowling sides to aft fuselage interface.

For round #2 fill I went with straight West 410 and filled in the surface imperfections and added a bit around the edges where it transitioned into the bottom cowling carbon fiber skin.

I then did the same on the other side.

I then left the “micro” finish refill to cure overnight.

Chapter 25 – Bottom cowl seam

I’ve been having an internal debate for the last couple of days whether to use pour foam covered with a ply of BID or simply apply “micro” to the side of the cowling to fill in the quite notable trough at the bottom cowl side interface with the aft fuselage side (on both sides fo the airplane).

I decided since I would have to do subsequent fills of micro that I would simply slather it on and go for it on the sides of the bottom cowling.  I had already marked off the approximate fill area, so I mixed up a bit of West 410 + micro and applied it.

I will note that I regret not getting some pics of the depression along the vertical seam of the bottom cowling and aft fuselage.  I will also note that I’m doing a minimal fill just to knock out the really obvious depression…. both for aesthetics and also for smoother airflow along this area of the fuselage/cowling.

Yes, these applications of “micro” or not the prettiest, but I’ll highlight again that this will be an iterative process.  First, getting the bottom cowling edges squared away a good bit, then I’ll start “the match” and work the aft fuselage side to get these areas as smooth, even and depression-free as possible.

With that, I left the “micro” to cure overnight (I did do a good bit of cheese grating about 6 hours later, but I didn’t get a shot of that…. yes, I’ve been a bit remiss on my pic taking duties).

 

Chapter 25 – More cowl seam tweaks

Today was yet another light build day, although I did get some stuff knocked out.

I taped up and clamped popsicle sticks pressed up against the cured flocro edge that I just filled in at the edge/seam gap between the bottom cowl and strake.  I wasn’t able to easily get up under the armpit scoop to fill in the remainder of the gap, so today I’m simply filling in the last few inches… using the taped stir sticks as a straight-line extension to the previous flocro.

Here is the right side strake aft edge flocro fill.

And the left.

I had previously sanded and prepped the area around the CAMLOC points on the vertical sides of the bottom cowl to allow me to also add a flocro “ring” around the CAMLOC mounting holes.

I’ve seen a fair number of Long-EZs where the holes have worn through at CAMLOC and screw points, and I didn’t want this to be the case on my bird.  Remember the ‘ol “egg on a can” example I used to describe my aft fuselage to bottom cowling interface?  The depression at the vertical side seams is actually more pronounced than what is depicted below.

Well, I’m filling that depression –on both sides (red arrows)– and this is the start of that effort.

Tomorrow I’ll continue on with my bottom cowling front edge tweaks.

Chapter 25 – Cowl flocro edge fill

I didn’t get a lot done on the plane build today, but after doing a good bit of assessing on the interfaces and intersections of the bottom cowling with the wings, strakes and lower aft fuselage, I got one significant task knocked out… or at least started: the fill of the gap between the front horizontal edge of the bottom cowl lip with the aft edge of the strake bottom skin. There was a gap that ranged from about 0.020″ on one end to about 0.1″ of on the other end that needed filled.

So I taped up the front edge of the bottom cowl and then remounted the cowl.  Here’s the cowl left side (right side as inverted).  I stopped the flocro fill of the gap about half way to allow for a good visual on what I was up to.

I then finished the gap flocro fill on the outboard side.  Note that I didn’t get the gap filled all the way up “under” the armpit intake scoop as I’ll do it tomorrow after this round of flocro cures.

I then repeated the same thing on the right side.  The gap on the right side wasn’t as big as on the left, but it was certainly significant enough to require added flocro to close it up.

I should point out that I spent a good 45 minutes sanding down the strake side of these interfaces BEFORE I applied the flocro to better align the surface levels of the bottom cowl and the aft strake edge.  I’ll tweak that level more after I get the flocro gap edge in.

 

Chapter 25 – Finished wing undersides

My cell phone screen was cracked so I was unable to take & post pics for a few days until I got a new one.  In the meantime I finished the sanding and contouring of the right wing’s bottom surface. Again, as much as will be done before the fuselage is flipped upright and the winglets attached.

And here is another shot of the finished left wing bottom surface.

Note that in these pics I’ve remounted the bottom cowling and am starting the multi-day assessment and micro-fill process of tweaking all the interfacing edges of the bottom cowling.

I also removed all the protective tape from the edges of the nose gear fairing and nose gear doors.  I then cleaned up the micro edges of these respective depressions to allow the gear to cycle freely, with the nose gear fairing and doors seating cleanly and with a bit of clearance all around.

Part of my tasks in the next couple of days is to do the final sanding of the micro on the bottom of the fuselage and nose to very closely match the elevation of the nose gear fairing and doors… just some minor tweaking.

Again, I’ll also continue working the edge interfaces on the bottom cowling and get that tweaked pre-fuselage-flip back upright.