Ok, folks . . . time for a chat. No pics.

After a lot of thought, research and assessing what we would call in military planning as COAs, or courses of actions, today I came to the hard realization that I need to install the lower engine cowling.

The reason why I had decided not to go with my original plan to install the lower engine cowling when the bird was flipped upside down was in part what the plans stated, what other builders had done, and what conventional wisdom pointed to . . . and that was that the cowling should be installed with the engine mounted in place.  Makes total sense.

But at this juncture I find myself in the “what comes first?” or proverbial chicken-vs-egg argument.

I don’t feel right in proceeding with the glassing of the lower aft fuselage/Hell Hole with an unquantified variable out there: the bottom cowling interface.  To go back and have to do rework of the lower aft fuselage once the plane is back upright, defeats the true purpose of doing it now while the fuselage is inverted.

If I am to define my problem, the two antagonists are 1) the lower aft fuselage needing to be reworked once the plane is upright and the bottom cowl gets installed, or 2) the bottom cowling isn’t aligned perfectly with the engine, specifically the flywheel and prop spinner flow guide.

Antagonist #1 could end up being a royal PITA to have to deal with later, once the fuselage is back upright, and could very well actually be a big frustration in getting the bottom cowling mounted.

Antagonist #2 seems the least sinister of the two.  If I align the bottom cowling centered on the fuselage centerline, then how far off do I really expect my engine to be one way or the other?  Not much at all.  And I do have the ability, although not desirable, to trim away or rework the bottom cowl once the plane is flipped back upright.  Even at that point the bottom cowl install would be virtually completed, as well as the bottom aft fuselage/Hell Hole, bottom fuselage-to-bottom cowling interface, and the RAM air scoop install… all dialed in to each other with good tolerances.

Thus, at this point I see no other option than to focus my immediate efforts on getting the lower engine cowling installed as I also press forward with the final configuration of the aft bottom fuselage/Hell Hole completion.

That’s what it quite often seems like to me when using pour foam: fresh baked bread.

Today I started off by creating a form and then pouring pour foam to add strip #4 to the left side (right as situated) of the current Hell Hole opening.

I measured out the required size for the ply of BID I would need, then cut it and put it in plastic to pre-preg it.

After shaping and leveling the outer surface with the surrounding foam, I then laid up the 1-ply pre-pregged BID on the inside of this new foam strip #4.  Of course the BID overlapped onto the surrounding BID from previous layups.

I then peel plied the layup and left it to cure.

A bit later I did pretty much the same thing for Hell Hole foam strip #5, which is the last of these pour foam and glass strips.

After shaping and leveling the outer surface, I then laid up the ply of BID on the inside of this last strip. Of course I peel plied it as well.

From here on out the emphasis for the aft bottom fuselage and Hell Hole cover will be the shaping and blending of the outer foam surface to meld in with the existing fuselage sides and bottom surface.  In addition, I’ll be focusing on fitting and mounting the RAM air intake scoop.

Which I spent a good hour and a half carving and shaping out of a big block of wing foam.  A huge thanks goes to Dave Berenholtz here, who was kind enough to share the math on his RAM air scoop, allowing me to create this with much less brain power required on my part!

I’ll be doing some heavy duty design and process flow planning over the next day or so to ensure I get this RAM air scoop integrated into the Hell Hole cover in as optimized of a way as possible.

Today was a short work day since I had some personal stuff I needed to take care of.  However, I was still able to get another strip of foam added to the Hell Hole cover/floor.

This strip of foam, about 2.5″ wide, filled in right behind the previous one at the front side of the Hell Hole. I set up my dam/form just as I did before, even with the requisite clamps.

I then whipped up some pour foam and poured it into this next section of Hell Hole cover/floor.

A bit later I pulled the form off.

I shaped the outer surface of the freshly inlaid pour foam section to match the surrounding level of the existing foam, and then prepped the interior surface for glass.

I laid up a ply of BID overlapping about an inch on all sides, again on the inside surface.  I then peel plied the layup.

I’m thinking that tomorrow I should be able to finish the repetitive task of pour foam and glass and move on to constructing the RAM air scoop.

Today was all about refining the aft bottom fuselage and Hell Hole cover plan, and then filling in the parts of the remaining opening between the two Hell Hole side fills that covered the bottom surfaces of the main gear.

The goal here is to fill in a good majority of the Hell Hole cover, or floor, in small sections that can be somewhat easily and manageably glassed.  The first strip was along the aft edge of the lower fuselage where the Hole Hell arguably officially starts.

I made up a duct-taped-covered cardboard dam/form/mold and secured it in place.  The clamps on each side are pressing against wood strips that keep each end of the flat mold piece pressed tightly against the existing Hell Hole floor.

I then whipped up a batch of pour foam and poured it into the form.

Here’s another shot of the quick-curing pour foam.

I had assistance today from my beautiful helper, Jessica —in her shop debut— as she very adeptly cut, cheese-grated and leveled the freshly inlaid pour foam to match the existing sides.

Here’s the final result from Jess’s handiwork… very nice.

I then walked Jess through her first fiberglass layup as we got the front edge of the inside Hell Hole to aft fuselage edge glassed.

Jess then helped me make up the form on the aft side of the Hell Hole opening, on the front side of the firewall, with a strip about 2.5″ wide.  She whipped up her first batch of pour foam and did an excellent job filling in yet another section of the Hell Hole cover/ floor.

Although I didn’t get any pics, a bit later I then removed the excess foam off this last pour and shaped/leveled it to match the foam on each side.  I then glassed the inside surface with a ply of BID overlapping onto each side and of course also onto the firewall.  All the layups were peel plied on the Hell Hole floor surface (foam) as much as possible.

Tomorrow I’ll press forward with filling strips of the remaining Hell Hole opening in and then glassing them on the inside.

I started out today trimming the inside right Hell Hole wall/corner/floor layup and pulling the peel ply.  It’s not the prettiest layup on this bird, but everywhere I looked it came out nice and solid.

Here’s the aft side where the interior right Hell Hole wall intersects with the front face of the firewall.

Before I proceeded any further on enclosing the Hell Hole with foam and glass, I figured I needed to run the Nick Ugolini Princeton Long-EZ fuel tank probe wires from the Hell Hole up (again, down in this configuration) into the CS spar.  Even with the bird inverted and most of the Hell Hole open it took me about 45 minutes to run the right side wire, whereas it only took 3 minutes to run the left.

I then built the form over on the left side of the fuselage to fill in below (above as situated here) the gear leg and create the left side lower “corner” wall for the Hell Hole.

Here’s another shot of the left side form, from the outside.

I then filled it up with pour foam.

And removed the forms a bit later.

Here’s the lower left side Hell Hole “corner” foam in its initial state.

I then cut, sanded and filed both the inside and outside of this freshly poured foam.

And then laid up a ply of BID, in 5 pieces… so there were a number of overlaps.

Here’s a final shot of the lower Hell Hole “corner” glassed on the interior.  Note that I peel plied from the inboard edge outward with a 2″ wide strip.

I then left the layup to cure overnight.

I started this morning by filling in the very aft area of the lower fuselage with pour foam, obviously inside the dams/forms I created last night.

A little while later I pulled off the forms.

Here are a couple side shots of the applied pour foam up to this point.

And a look at it from the aft firewall.

I then used a hacksaw blade and my “cheese grater” to knock down big pile of cured pour foam.

I then set up a form to fill in the area under (“over” when inverted) the right gear leg.  In addition, in this inverted state I set up a “floor” to in turn create a section of the bottom floor of the hell hole. Moreover, I set up the thickness so that once the foam cures it’s at the appropriate height to glass almost immediately with only minor tweaking.

Here’s another shot of the form for the right hand “corner” of the exterior hell hole floor/wall.

And a couple external shots of that form configuration as well,

And here is all that with the pour foam in action.

After the pour foam cured, I then removed the forms and knocked down the excess foam.

I then dialed in the surface level of this freshly added foam with my sanding block.

I cleaned up the inside, removed excess foam and sanded the surface to rough it up a bit from the smooth glossy surface it gets from curing against duct tape.  I also ensured all the transitions between foam and existing fuselage structure was even and worthy of glass.

After micro’ing up the foam I then laid up a ply of BID, in 3 pieces, that overlapped onto the lower longeron, firewall and aft fuselage edge. I then peel plied the inboard (nearest the opening) edge with 3″ wide peel ply tape.

This was definitely a challenging layup primarily due to the lack of access I had to the areas where I was laying up the glass.  I used the bigger stir sticks as a squeegee in the corners and to ensure the glass was attached to the foam with as few bubbles and air gaps as possible.

I then left this layup to cure overnight.

Today I started out by removing the NACA shaped plug from the NACA scoop I glassed last night with 2 plies of BID.  I also razor trimmed the glass and pulled the peel ply up.

As with many things on this build the scoop isn’t perfect, but I’m thinking it meets the minimum design criteria and will work fine.  Its appearance of course will look much better after some micro finishing.

I then turned my attention to the strake/wing junction layup that I also knocked out last night.  I secured a long straight edge to the marked intersecting line with a clamp and tape.

And then cut the line with the Fein saw.  I was able to remove the tape and foam from the first 10″ or so, which provides a pretty good view of how the entire intersection will look.  I’ll add a ply or two of BID on the inside to reinforce these flanges once I remove the wings.

With the strake/wing intersections glassed and gap minimized to about 1/16″ I then pressed forward with filling in the lower aft fuselage and hell hole.

I’ll state that of course there is no one right way to do this, and I’ve seen a lot of builders simply create dams and pour all the foam virtually at once and then start carving.  I would probably do this normally, but in my current mood I decided to attack it with a bit more precision.  Which of course will take a bit longer.

I started on the right lower sidewall, just above the gear leg, to create the lower fuselage wall.  My goal is to create the wall about an inch thick that will then allow me to roll right into glassing the interior surface of the hell hole.

I also want to get the requisite gaps in place on the top of the gear leg (underside as situated here) taken care of right off the bat, then get the lower gaps (topside here) taken care of in short order following that.

Another shot of the right internal lower fuselage/hell hole wall forms.

I then created an external side form for the lower right fuselage.  Not surprisingly, it took a bit time –trial and error– to make these forms.

I then taped the external lower right fuselage form into place.

Here’s a view from the “top” side . . .

And a shot after I poured the first batch of foam into place on the lower right fuselage.

Here’s a shot a bit later, with the lower left fuselage foam poured in place.

Also you can see where I determined the point of conversion on the lower fuselage with a straight line coming from the firewall bottom edge.  I marked these convergence points — left, right and center– on the lower fuselage (abound mid-point on the Kevlar) and then built a dam just a bit forward of the convergence marks.

Here we have the front area –on the lower aft fuselage– all dammed off and ready for pour foam.

It was quite late at this point, and since pour foam cures fairly fast I decided to call it a night and start fresh tomorrow.

Over the last week or so I’ve asked Marco to take some pics of his flying bird, JT, as he has it down for some upgrades.  The pics I requested were of the strake-to-wing junction since I suspected, and had noticed in passing, that they were not constructed as the build plans would have you do so.

Today I doubled down on my effort to come up with a plan for creating both the wing and strake intersection (gap) lips.  I noted my buddy Dave Berenholtz went with 3 plies of BID across the gap, and then micro filled later.  In retrospect this may have been the easiest route and I mighta oughta shoulda taken it.

I also queried Mike Toomey on how he went about working his strake-to-wing junctions, which was fairly inline with what I found in the old CSA issues as spelled out by Ken Miller.  They both recommended filling the gap with foam first, then glassing.

Regardless of any method I used, the front edge of the right wing needed the micro fill that I had put on years ago to be removed before I could layup any glass over it.  So I marked a line about 1.5″ wide…

and then sanded away the micro fill.

As per Ken Miller’s instructions, I used a long straight rule that allowed me to make alignment marks on each end for what will be the cut line that will mark the respective edges of the glass lips… which themselves will cover this gap.

Somewhat like Marco’s bird JT, I wanted the major/wider lip on the aft side of the strake, and the minor/narrower lip on the front of the wings.  I taped a temporary 1/4″ plywood spacer onto the front face of the wing to give me what will be that narrow lip.

Here’s another shot of the long rule and marks to create a narrow lip on the wing side and wider lip off the strake.

Since I have so much scrap urethane foam hanging around, I went ahead and used that to fill in the strake/wing gap… again, as per Ken Miller (urethane) and Mike Toomey (spray foam).

After sanding down the foam and shaping it to be as good of a bridge as possible between the slightly uneven surfaces of strake and wing (a bit more pronounced on the left side), I then taped over the top of the foam with a strip of duct tape to act as a mold release betwixt glass and foam.

I then laid up 2-ply BID tapes on each side, with the bottom tape being 4″ across the gap, fairly centered, and the top ply being 3″ wide across the gap… again, fairly centered. I then peel plied the layups.

Today I also finalized my research on creating a NACA scoop for the GIB air vent. I have never constructed or designed a NACA scoop, and again I just used the template that was in the plans for the canopy skirt air vent.  I did want to ensure that since this is a bit different construction technique than the canopy skirt vent that my internal scoop design was optimized.

I’ll say again (maybe?), thank goodness for the searchable CSA newsletter thumb drive I bought… great archive of really good info.  With that in my back pocket I tweaked the NACA scoop a bit before prepping it for glass.

As you can see, I also created a foam plug to help press all the glass outwards against the sidewalls and down onto the “floor” (as situated) of the scoop.

I laid up 2 plies of BID inside the NACA scoop, after creating essentially flox corner walls.  I then peel plied the bottom surface of the scoop and then put the foam plug in before weighing it down with almost 20 lbs of weight.

Tomorrow I’ll clean up these layups as I move on to shaping and glassing the aft bottom fuselage and hell hole cover.

One of the main reasons I mocked up the lower engine cowling was to determine the intersecting lines between it and the lower firewall.

I played around with the cowling for quite a bit to get it set the best I could against the firewall.  It may not be perfect and I realize some rework may be required, but I have to have a starting point if I am to fill in the bottom of the hell hole area and create the lower aft fuselage section.

With that, I trimmed the firewall to create an edge for the upcoming lower aft fuselage and hell hole.

Over the next few days I plan on slowly building “up” (technically down of course) the sides of the fuselage which will then culminate in me creating the bottom of the hell hole cover with an integrated RAM air scoop.  That’s the plan at least.

Before I started the cleanup on the right strake bottom skin layup I wanted to get the ply of Kevlar laid up on the bottom aft fuselage… that will serve to protect the bottom side of the GIB thigh support sump tanks if I were ever to have a hard landing that ripped the main gear off and resulted in a belly slide down the runway/ground.

I made a bit of indentation on the aft side of the Kevlar ply in case I need to dig into the original bottom aft center fuselage for positioning of the RAM air scoop that will be coming soon.  After I laid up the Kevlar I peel plied it.

Also, I should note that before actually laying up the Kevlar, I test fitted the left and right fuel sump drain valves to ensure I had enough clearance around them to insert a socket on them to install them.  The right side channel in the bottom skin needed to be widened just a hair, and after I got it so I could slip a socket in there I proceeded laying up the Kevlar.

After nearly 2 hours of cleaning up the bottom right strake layup and removing all extraneous glass, I then cleaned and mocked up the bottom engine cowling.  I went ahead and temp mounted the armpit air intake scoops as well to get an idea how they will fit.

Here’s the protective Kevlar ply on the aft bottom fuselage after it cured and I pulled the peel ply.  At this point I dug out the foam around each of the thigh support fuel sump drain valve points and filled in the edge of the channels with flox, not only to provide a stronger bottom fuselage skin to internal skin bond, but to clean up the raw foam appearance of these drain valve points.

With the drain valves and the center threaded hardpoint that installed before I skinned the outside the fuselage eons ago… I think the Kevlar looks like Pokémon!

Also note the right strake glassed trimmed away from the GIB strake window and the GIB air vent NACA scoop.

The next few days are going to be busy with some social events, but I will attempt to press forward as much as possible on the aft bottom side of the fuselage and hell hole.