I started out today by sanding and shaping the micro fillet I inlayed around about half of the junction between the aft RAM air segment and the front face of the firewall. I’ll do one final tweak, but I’d say this gets me very close to where I need to be… at least 80-90%.

I then got to work on the RAM air scoop aft structure-mounted NACA scoop that will supply cooling air to both the PMAG electronic ignition and the engine driven fuel pump. The template I used was right out of a CSA article on NACA/flush-mounted scoops.

Now, to be clear this is a bit of an experiment on yes, an experimental aircraft.  I say this because there are 2 factors that make this a non-typical NACA scoop install… at least in my book.  I could very well be wrong of course.

First, the segment of RAM air scoop structure that this NACA is embedded into is not flat, as you can see here.

Next, and although I didn’t get a shot of it (yet).  The portion of the RAM air scoop aft structure where this NACA scoop is located is just aft of where the profile of the scoop structure starts to turn upwards to eventually blend into the bottom cowling.  Since it’s not on a straight and level segment of the bird I’ll have to monitor how it does.

To be even more clear, if this turns out to be a big fail it would take maybe 2 days to rip it out, fill the pocket with pour foam, glass over with a ply of BID and then spend a day or two painting it.  Barely any, if any, added weight in removing it.

I then got busy on the NACA fitting that will jut out of the aft side of the NACA scoop. This fitting will slide into a connector that will connect the NACA to a 1.25″ diameter SCAT tube that carries the air into the engine compartment.  I had been shooting for a 1.5″ diameter SCAT tube, but space is tight in this area, especially in the firewall bridge.

Once I got the configuration of the aft NACA fitting set (or so I thought), I secured it with tape and then poured foam around it.

Here’s a bit after I hacked off some of the pour foam. Note the blue foam in the front portion of the NACA fitting to keep pour foam out.

I then test fitted the NACA fitting position and didn’t like what I saw.  It was a bit too high and too angled down.  It was a good (better?) position most likely for air flow (that’s the whole point, right?!) but getting the RAM air scoop/hell hole hatch cover on and off was just not going to happen with the NACA fitting in this position.  I needed to lower it just a hair, and straighten/level it just a hair more (less angled) for it to work.

Here’s the final position I settled on. My intense background in armchair engineering makes me think this will get cooling air to the targets pretty darn close to what the previous position would have…. at least that’s what I choose to believe! <grin>

I micro’d the bottom portion (as situated in the pic) and laid up some BID around it to secure the NACA fitting.

I also taped up the end of a 1.25″ aluminum tube with a taped up toilet paper roll sticking out of the end to make my male/female connector to connect to both the NACA fitting above and into 1.25″ diameter SCAT tubing.  I then peel plied this 3-ply BID layup.

My last task for the evening was to use the original somewhat-aerodynamic S-glass grazing nub —in lieu of a hockey puck… this was before Marco machined me a very aerodynamic/cool bumper from a hockey puck— from Feather Light as a mold for my bottom center line-mounted, aft-facing video camera. I didn’t need quite the height for mounting the camera and I definitely didn’t need a heavy, solid S-glass piece to mount it into… but I liked the shape so I just glassed a few plies of scrap BID over it.

I’m guessing in all my machinations tonight I forgot to grab a layup pic of the video camera mount housing, but a few hours later I pulled the layup from the mold and cleaned it up. Here it is.

Tomorrow I’ll continue to work on the NACA scoop and all the tasks on the bottom of the bird so I can get it finished for paint and then flipped back upright post haste.

I started out fairly early this morning to get the last set of 2 pairs of CAMLOCs installed on the belly of the fuselage to secure the RAM air scoop.  Unlike the aft flange-mounted pair of CAMLOCs, these 2 are much more challenging in that when I cut into the added foam layer of the aft bottom fuselage, the depth wasn’t far enough to allow the CAMLOCs to compress far enough and operate as designed.

Last night, after pondering on it for a bit, I decided to press forward and simply cut further and deeper into the original bottom skin of the fuselage —directly beneath the GIB seat pan— and get my needed 1/8″-3/16″ added depth there.

In the pic below you can see I did exactly this on the right side (bottom of pic) . . .

I then tested out a -2 CAMLOC installed in one of the threaded-CAMLOC receptacle phenolic blocks.  It fits! . . . whew!

I then did the other side… here I show some of the mess involved in doing so.

I then taped up and floxed the threaded-CAMLOC receptacle phenolic blocks into the bottom of each hole, so that technically the top of each CAMLOC block is floxed directly to the underside of the GIB seat pan glass.

I then laid in 2 plies of BID with a center hole cut out for the CAMLOC.  I then inserted, tucked, jammed the glass up under the lip around the edges of each square cutout.  I then mixed up drier micro and pressed the glass fully into the recesses along the edges.

Here’s the results.  Not bad. Also not pretty.  But it will definitely work!

And a wider angle shot so you can get your bearings on where all this is going on.

I then ran a plumb down the aft centerline of the RAM air structure and bottom cowling to ID the spot for the bottom cowling BDC CAMLOC.

I then installed what should be the last CAMLOC I install while the bird is flipped inverted… the next round of CAMLOC installs should come while I’m installing the upper cowling.

I then remounted the bottom cowling and tested out my BDC CAMLOC install… worked a treat!

And again, thankfully nether RAM air scoop/hell hole hatch cover bottom center screw nor bottom cowling bottom center CAMLOC distorted the RAM air scoop aft structure in any way.

I grabbed a shot here showing the latest additions to the RAM air scoop/hell hole hatch cover: the right side CAMLOC and BDC screw.

And a couple shots of the new RAM air scoop flange-mounted CAMLOCs.  The depth on these threaded-CAMLOC receptacle phenolic blocks into the fuselage belly was more than  adequate since I ended up needing a -8 CAMLOC stud (whoa!)… which I only currently have 1 on hand.  I’ll order a couple more next time I submit an order to ACS or Skybolt.

It was getting late in the evening and my last couple of tasks were minor ones, but ones I wanted to cross off my list.

First was laying up a couple plies of BID around the aft opening of the forward RAM air scoop… the side attached to the hell hole hatch cover.  This opening got beat up fairly badly when I extracted the aft RAM air scoop piece —with freshly glassed flange— from this section.

As you can see, I then peel plied this layup.

Next, I removed the RAM air can and added some dry micro to the fillet on the inside of the RAM air scoop aft segment, at the junction with the forward firewall face. I”ll note that this will be an iterative process, so this is just another positive step in the right direction. I still need to clean up this application of micro and then probably add at least one more round.

I then let the micro and layup cure overnight.

Today was one of those tedious work days where it seemed like there was a ton of work done without a lot of results to show for it.

I started by pulling the RAM air scoop/hell hole hatch cover from the bottom fuselage.  I had to carefully rock it back and forth, up and down to get it to break free from the glassed flange that was gripping the mold-release packing tape on the inside surface of the aft RAM air scoop/hell hole hatch cover.

The flange turned out fine, and here’s another shot of it.

And a somewhat fuzzy shot looking through the aft end of the firewall bridge.

I then pulled peel ply, trimmed and cleaned up this forward flange on the firewall bridge.

I then spent a bit of time aligning and prepping stuff, that finally led to my installing a K1000-3 nutplate as the final aft secure point for the RAM air scoop/hell hole hatch cover.

Here’s an exterior shot of the latest installed screw point to secure the RAM air scoop/hell hole hatch cover.  Thankfully this screw point install didn’t mess up the nice flow between the forward RAM air scoop and the shape of the firewall bridge.

I then spent a good half hour pulling peel ply and cleaning up the RAM air scoop structure aft end: the bottom cowling.  Here’s a couple shots of the cleaned up pocket that now exists on the front edge of the bottom cowling.

I then set the cowling back in place and added some weights to each side of the new protrusion to press the cowling lip into better alignment with the firewall bridge.

After taping up the bottom lip of the pocket on the front of the bottom cowling –as a mold release– I then laid up a 2-ply lip and 3 more plies in the center for a 5-ply CAMLOC/Skybolt receptacle mounting flange… yes, it’s a bit difficult to tell since the colors blend, but the layup is down in there.  I also peel plied the layup.

One last shot of the glassed aft flange (AKA bottom cowl CAMLOC flange) on the firewall bridge.

I then left this layup to cure overnight.

Today I started out by spending well over 30 minutes pulling the peel ply and cleaning up the layup on the RAM air scoop aft structure.

I then razor knifed the seam between the center segment of the RAM air scoop aft structure, what I’m calling the “firewall bridge” and the front edge of the bottom cowling. The cut wasn’t perfect and I’ll have to clean it up a tad during the finishing stage.

I then removed all the CAMLOCs from the bottom cowling and separated it from the fuselage/RAM air scoop aft structure.

And voila! Section #1 separated.

I then did the same thing at the forward side of the RAM air scoop aft structure firewall bridge by razor cutting the seam.

I then unscrewed and removed the RAM air scoop/hell hole hatch cover from the fuselage. As you can see I was left with just the permanently attached RAM air scoop aft structure firewall bridge.

A shot of the firewall bridge from the front looking aft.

I then started cleaning out all the cured pour foam from inside the firewall bridge.

I didn’t use any micro on the foam around the firewall bridge, but did lay in some peel ply, which I pulled to have a nice clean surface for glassing.

I cut and prepregged 2 plies of BID and laid it up on the inside of the RAM air scoop aft structure firewall bridge, for a total of 4 plies of BID.  Before laying up the glass I created flox fillets in the corners to ensure as much strength and rigidity as possible in the firewall bridge structure.  I then peel plied the layup.

After removing the first 2″ of foam from the aft side of the RAM air scoop/hell hole hatch cover portion of the RAM air scoop aft structure, I then took it outside and cleaned up the glass with a Dremel tool sanding drum and some sandpaper.

I then laid up 2 plies of BID inside of that aft area.  Since a screw will secure this portion of the RAM air scoop/hell hole hatch cover at bottom center to an upcoming flange on the forward side of the firewall bridge, I added a small 2″-wide ply of BID in the center of the layup (for 5 plies of BID total on the bottom center).

I then peel plied the layup.

I then got to work doing pretty much the same thing on the very aft side of the RAM air scoop aft structure: the bottom cowling.  I cleaned out the foam and sanded/prepped the cured glass for fresh glass.

Since nothing else will be glassed or embedded here, I went ahead and glassed the aft foam wall to create a pocket with the bottom (curved) side with 2 plies of BID (added here, so 4 plies total).  I then peel plied the layup.

I’ll note on the 2 pics above that from the camera angle you can see a sliver of the RAM air can notch I made in the bottom cowling.  Just for FYI, here’s the glassed, then foamed, RAM air can notch in the bottom cowling.

I then got to work on the last set of CAMLOCs that I’ll use to secure the RAM air scoop/hell hole hatch cover to the belly of the plane.  These are the 1/4-phenolic block-mounted threaded Skybolt CAMLOC receptacles that have proven phenomenal on this build.

I had previously drilled 0.150″ diameter holes (one each side) through the RAM air scoop mounting flange into the bottom fuselage skin (just enough to penetrate the skin) to mark the positions of the CAMLOCs on both the flange and the aircraft belly.

I now centered the phenolic CAMLOC blocks on these holes and marked the perimeter of the respective blocks.

I then used the Fein saw to cut the outer skin, cleaned and vacuumed out the foam and debris, and then test fitted the phenolic CAMLOC blocks . . .

At which point I realized I had a big issue to contend with . . . you see, the bottom of these holes weren’t deep enough for the CAMLOCs to compress as they should in securing the RAM air scoop flange.

In fact, the CAMLOC in the left foreground of the pic below is a -2 stud, the shortest available and it is still too long, sitting too high to work.

Clearly I needed to ponder my predicament and make both a decision and plan for a way forward.  I decided to sleep on it and work the problem tomorrow.

I moved on to my last task of the evening.  Laying up a 3 ply flange on the forward side, and attached to, the internal surface of the firewall bridge.  I taped up the inside of the aft edge of the RAM air scoop (all the previous layups were cured, BTW) as a mold release before laying up the 3-ply flange inside the firewall bridge, overlapping into/onto the forward RAM air scoop structure.

Moreover, to add more material to secure a K1000-3 nutplate, I added a 2″ wide 2-ply pad of BID to the bottom center (remember, inverted here, so top in this pic) of the layup.  I then peel plied the layup and let it cure.

Tomorrow I’ll continue to work the interfaces of the RAM air scoop aft structure and getting those darn CAMLOC blocks installed.

I started out today by pulling the peel ply and inspecting the 1-ply BID layup on the bottom surface of the lower cowling that will mainly serve to keep pour foam out of this clearance hole.

Moreover, I would say all is good but the glass at the corners lifted and separated from the cowling surface a bit.  This will be along the edge of the RAM air scoop aft structure, or swoosh, or “canoe” if you will and will need to be trimmed down.

I then test fitted the bottom cowling to check clearance between the RAM air can and this new glassed pocket.

A shot from inside the cowling.

I then placed my shop LED light in the hell hole facing out and remounted the RAM air scoop/hell hole hatch cover securely in place.  With the light shining though the LIDAR laser altimeter lenses’ holes I traced those holes on the surface of the hell hole hatch cover [Note the mounting base/flange to the RAM air scoop has been trimmed, see pics below].

I then drilled the holes with a hole saw bit and sanded them out to size in the hell hole hatch cover to allow the LIDAR laser altimeter lenses to see the world.  Note that prior to this I trimmed away the excess glass on the RAM air scoop mounting base/flange.

Another shot of all this from the side.

I then got to work on making up the 1/4″ thick phenolic inserts for the Skybolt threaded CAMLOC receptacles.  These CAMLOC receptacles will be the second set to secure the RAM air scoop base/hell hole hatch cover to the airplane belly.

I drilled holes and tapped 1/2-20 threads in the holes for the Skybolt threaded CAMLOC receptacles.

And then floxed the Skybolt threaded CAMLOC receptacles into the 1/4 thick phenolic inserts.

I then spent a bit finalizing my configuration for the RAM air scoop aft section structure. Using a taped-in-place flexible yardstick here is what the side profile will look like.

Before pouring foam though, I wanted to secure the aft inboard edge of the hell hole hatch cover as best possible.  Since the width and shape of the RAM air scoop is now known, I could proceed with installing the aft inboard K1000-3 nutplates.

Here’s the hell hole hatch cover back in place, with all the CAMLOCs and screws installed, including the 2 new aft screws.

I then constructed my pour foam dam/form out of taped cardboard.

An angled shot of the taped-cardboard pour foam dam/form for the RAM air scoop aft section structure.

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

Clearly it wasn’t enough foam.

So I waited my 10 minutes as per the directions and whipped up another batch and poured it in.

Much better this time, providing cover to all the areas.  So I pulled the forms and started the slow process of trimming down the foam.

Here’s round 1 of some honest foam shaping.

And a bit more after I pulled the taped yardstick… which defines the bottom surface outline.

A bit more focusing on the symmetry of the very aft intersection with the bottom cowling.

And finally I got all the foam shaped and vacuumed, ready for glass!

I just wanted to point out that this is all the BID I have remaining out fo the 10 yards I ordered from ACS not too long ago.  I have another bunch coming in early next week. Crazy how much glass, peel ply and epoxy I’ve been burning through these past few months!

In final prep for the 2-ply BID layup I marked and cut the foam RAM air scoop aft extension structure at the hell hole hatch cover aft line and the bottom cowling forward intersection line.  I’m calling the narrow area in-between the “firewall bridge.”

I then added a dry micro fillet around the edge of the foam and filled any larger areas in the foam surface requiring it.

I then laid up the 2 plies of BID.  Since this is just a fairing, and not a structural airframe component, I used West epoxy to save my MGS as much as possible.

Here’s a shot from the aft side.  The joggle in the centerline of the bottom cowl made the very aft curve a little challenging to nail down.  I’m going to have to call in some assistance from the finishing micro to dial this in exactly before paint.

And a whole now-completed RAM air scoop structure shot.

I then peel plied the layup… again, here we have a side profile shot.

And another long view shot. Yep, I used one piece of peel ply for the entire layup.

With that, I called it a night and left this layup to cure overnight.

I started out today by drilling out and removing the top skin to reveal a threaded hardpoint I had placed on the centerline of the fuselage aft of the landing brake —the aft of 2 hardpoints with the other forward of the landing brake— based off a recommendation from Dale Martin, back in 2012.  The idea was to allow for mounting a long strait piece of aluminum to ensure the engine, nose, etc. were centered.  I never used them (maybe I should have!) but knowing that this one was available I worked it into my design for securing the RAM air scoop.

I had a boss in the Air Force that often stated, “Luck is when preparation meets opportunity.”  And I feel that this hardpoint offered me a bit of luck.  Why?  Well, with having an internal GIB thigh support fuel sump, which led me to laying in a ply of Kevlar as a safety measure just in case I have an engine out landing that rips the gear off, and thus finds the bird sliding down asphalt on its belly, I wanted to have a protective layer to keep the fuel sump from damage in such a scenario.

All that limits my options on embedded hardpoints for securing the RAM air scoop.

The black Sharpie line is an initial arc around the front of the RAM air scoop for determining the size of the mounting flange.  Here you can see a screw in the threaded hardpoint.  You can also see there is only Kevlar covered by UNI for a good bit moving aft before any added foam starts appearing.

Onto the RAM air scoop mounting flange, I installed a countersunk screw into the hardpoint to make it a bit more visible. I then mounted the RAM air scoop/hell hole hatch cover.

I then drilled into the center of the screw to mark the center of the hardpoint, removed the RAM air scoop, drilled out the remainder of the screw mounting hole… then mounted the RAM air scoop back into place, securing it with the new screw attach point.

I will note that my optimum design would not have a screw dead center in front of the RAM air scoop inlet, but I think the chances of a properly mounted screw coming out and going into the intake is remote.  Moreover, beggars can’t be choosers!

Now lets discuss the other hardpoints along the sides of the RAM air scoop.  The farthest aft, about 2-3″ forward of the original front edge of the hell hole hatch cover, will be a pair of CAMLOCs… making up 4 CAMLOCs total used on this RAM air scoop/hell hole hatch cover.

Forward of those CAMLOCs the thickness of the foam starts diminishing quickly.  I was going to use K1000-3 nutplates secured to phenolic, as I normally do.  But when I tested the thickness of these EZ Point locking nuts I discovered they were over a 1/16″ shallower in depth than a phenolic nutplate assembly… yes, I’m scrambling for as thin as possible to allow me to place a pair of RAM air scoop securing screws as far forward as possible. Also note these are 1/4-28 size, so I ordered a pair of 10-32 EZ Points from Aircraft Spruce.

I then got busy filling in the gap that runs along the side and in between the RAM air scoop and it’s mounting base/flange.  This was the initial pour, and I needed another one to finalize the fill on the side of the RAM air scoop assembly.

While the different rounds of pour foam cured on the RAM air scoop, I installed the RAM air can on the back of the firewall. Here it is mounted with 5 SS screws from inside the hell hole (see pic below).

Here we have a side view showing the aft edge of the RAM air can peaking up above the horizontal line going back from the flange around the bottom of the firewall.  This is even more significant given that the bottom cowl tapers up as it moves aft, so the can needs to poke through the bottom of the cowling.

Here are the 5 SS mounting screws from the inside of the aft RAM air scoop section.  And yes, I need to add to/clean up the fillet on the inside aft edge of the RAM air scoop section.

Here’s a shot of the RAM air can peaking through the bottom of the cowling.

I took the bottom cowling outside and cut just a hair more of this notch to allow a scant more clearance between RAM air can and bottom cowling.  I also sanded the carbon fiber surrounding this notch for glass.

After remounting the bottom cowling, I used taped cardboard to add a little padding around the RAM air can, then cut a scrap piece of BID.

I then laid up the BID and peel plied a good bit of it.  This glass will created a barrier when I later add pour foam to the bottom cowling as an aft extension of the RAM air scoop assembly.

I then spent a good bit of time shaping and cleaning up the added pour foam on the RAM air scoop.

I then remounted the RAM air scoop/hell hole hatch cover back in place on the fuselage in preparation for glassing.  I glassed layup #5, which is the final layup for the RAM air scoop base/mounting flange.  I also laid up a strip of BID aft of layup #5 to cover the aft foam transition area.

Here are a couple more shots of these layups.  Note that I peel plied all the layups.

And one final shot of peel plied layup #5.

I then called it a night and left the layups to cure overnight.

It hit me about 5am this morning that I should have pulled the protective tape after just a few hours of the landing light lens perimeter glass layup curing… but I didn’t. When I pulled up the tape there was some epoxy that had seeped up onto the lens and cured (sorry, no pic).  And it of course was stubborn and didn’t want to come off easily.  I tried a plastic razor blade just for this occasion (one would think!) and it did nothing.

I then grabbed some white vinegar and soaked down a paper towel and let it sit for a good 5 minutes on these ugly intrusions onto my landing light lens.  Then, as carefully and as lightly as I could, I used a razor blade to skim off these cured bits of epoxy.  For the most part it worked a treat, although on the right side in the pic below you can see some scratches.  I’m hoping those will buff out… and clearly that’s simply cosmetic and doesn’t affect the functioning of the lens or landing light in any way.

All told, this was a good hour-long endeavor.

I then pulled the peel ply and cleaned up the layups on the interior side of the RAM air scoop securement to the hell hole hatch cover.  Layups looked great and I’m very pleased with how they came out.

I then reset the RAM air scoop/hell hole hatch cover back in place and secured it with the CAMLOCs and screws.  It fit a treat and so far it seems to be functioning exactly as I designed it and hoped it would.

I wanted to capture the fact that even with the shallow ‘S’ curve in the RAM air scoop design, that you can see through it from one end to the other.  Here I grabbed a pic of something that was fairly bright and visible —a heart candy tin from Valentine’s Day long ago, which is where I now store the LIDAR laser altimeter.

Here’s what it looks like from the topside, just FYI.

I’ve had an ongoing internal debate in my mind whether to simply use pour foam to clean up the interfacing edges of the RAM air scoop and its base, or to also add in a supporting spline —akin to what an F-16 has between engine air scoop and fuselage bottom— betwixt the two… so I cut a thin cardboard template to test it out.

I liked the way this looked and felt I could integrate it into the design.  I will note that I plan to lop off 0.4″ from the front air scoop inlet so the spline won’t be set as terribly far back from the inlet opening as it is here.  A bit back, yes, but not too crazy (I hope!).

I then transferred the cardboard template to my stock of 1/16″ thick G10 phenolic and cut out the real version of the supporting/interconnecting spline. Again, with my cheap band saw it’s not perfect, but it will do (pic #1).

It then took a few iterations of test-fitting and sanding to get it to fit just right (pic #2).

I then 5-min glued the top and bottom edges of the RAM air scoop-to-base supporting/ interconnecting spline.  I set it and weighed the top to maintain my 0.95″ gap between base and air scoop inlet opening.

Here’s a view of both supporting/interconnecting spline and down the chute of the RAM air scoop.

I then measured and cut 2 plies of BID.  They are both opposite “L” shapes, so one like this: ⌈ and the other like this: ⌉ with the horizontal sections overlapping each other at the very forward end of the RAM air scoop base … as I’ve labeled the pic below.

Since I wanted the support base mounting flange to be 5 plies thick, this layup completes the front section of the base from the front edge of the supporting/interconnecting spline forward.  I will then fill in the area from the front edge of the supporting/interconnecting spline AFT with pour foam to eliminate a good bit of intersection drag.  The layup that covers that along the side will be layup/ply #5 for the side runs.

As you can see, I of course peel plied layup #4 (or #4.5 if you will).

Tonight was an early evening off as I went to dinner a bit earlier than normal and simply relaxed… I’ll be back at it hard tomorrow.

Today i started by pulling off the now combination RAM air scoop/hell hole hatch cover from the hell hole/fuselage bottom.  Although I had taped up what I could in the hell hole, I was hoping not to find any errant epoxy, flox or micro had welded any parts of the forward and aft RAM air scoop sections together…. thankfully nothing like that happened and with just a scant bit of wiggling and rocking the entire assembly popped off.

I then assessed the interior situation of my hell hole hatch cover/RAM air scoop assembly. To be honest it’s a bit chunkier in weight than I would prefer, especially given the original plans weight of things down here is a shaped piece of urethane foam micro’d into place and secured by a single ply of BID.  Uh, this thing is a bit more robust.  So the last thing I wanted to do was add more weight in securing the interior RAM air scoop to the interior hell hole hatch cover.

Something had to go to at least make this a zero sum endeavor in regards to weight.

Moreover, I’ll note that this is the epitome of armchair engineering in that I didn’t weigh things before or after, I just lopped off what looked heavy (unneeded multiple plies of glass) or unbalanced (extra foam on one side) and went for it.  I’ll further note that I certainly needed much of the extra glass and depth in foam pre-RAM air scoop install, but now that it’s securely integrated into the hell hole hatch cover, much of this stuff is now longer required… yet another reason it can go.

Thus, I marked the offending areas with hash marks.

Took the entire assembly outside and went to town on it with the Fein saw, Dremel tool and sanding blocks.

Back inside we have a sanded and cleaned up version pretty much ready for glass.

First I filled the narrow trenches between foam and RAM air scoop with pour foam.

The long view…

And then made some patterns out of clear plastic to then cut a single ply of BID each side.

Micro’d the foam and laid up the plies of BID.  I then peel plied the layups.

With the RAM air scoop/hell hole hatch cover interior layups curing, I then got back to work on the nose landing light 1/16″ thick lens install… for a more final install on this landing light lens to complete this task before flipping the bird back upright.

Note that I added narrow strips of clear packing tape around the edge of the lens simply to keep the entire perimeter edge clean of micro so that if I need to pull this lens in the future, the micro doesn’t have a death grip on the lens.

In prep for glass around the perimeter of the lens, I melted some wax and filled the Phillips head slots of the screws to keep epoxy out of there as well. I then scraped off any excess wax and carefully cleaned the perimeter lens with acetone (pic #1).

I then added micro around the perimeter edge of the landing light lens (pic #2).

I laid up an initial ply of BID that covered up to the edge of the lens, so surrounding the perimeter to about an inch out —essentially covering the micro “fillet” outward.

The final and second ply of BID actually overlapped about an inch onto the surrounding nose glass and covered the perimeter of the lens right up to the edge of the protective tape. I then peel plied just the top lens perimeter edge of the glass.

And with that, I left my multiple layups to cure overnight.

Today I started with a fairly early morning pair of single ply BID layups to more fully secure the inside front lip of the hell hole hatch cover to the extended glass base for the RAM air scoop.

I actually cut out the foam almost an inch deep into what was left off the front side foam face of the hell hole hatch cover. I then sanded and prepped the area for glass before cutting the 2 separate pieces of BID.  As you can see, I had to notch the BID plies to go around the intersection where the slanted top inside edge (or “floor”) of the hell hole hatch cover dives into the exterior surface.

To be clear, the layups will go where I’m pointing to with the yellow and black tipped pointer.

I then laid up the respective plies of BID (pic #1) and then peel plied them (pic #2).

Jumping ahead quite a few hours, here’s what these layups look like cured, with the peel ply pulled.

While the layups above were curing, and I couldn’t work on the hell hole hatch cover nor the RAM air scoop install, I got to work on one of my inverted fuselage tasks: the replacing of the much too thick 1/8″ nose-mounted landing light lens for a more diminutive 1/16″ thick lens.

I first grabbed the sheet of 1/16″ thick plexiglass and used the old lens as a template to mark up the new one.

I had looked around for a good jigsaw blade to cut the plexiglass and finally found one that would work (yep, last place I looked!)… and quickly cut out the new thinner lens.

I then drilled and bore the countersink holes for the #8 stainless steel CS screws and test fitted the new lens.  I have to admit that part of the problem with the old 1/8″ thick lens might have been that it was overlapping the lens inset, that I had created when I made the original sunken lip —compared to the surrounding nose—for the lens to sit down into.

The bottom line is that the lens was not sitting in its depression correctly and needed some trimming.  Instead of taking the lens off and cutting it with the jig saw again, I decided to just trim it (judiciously!) while still mounted to the nose with a cutoff wheel in the Dremel tool.

Here’s a look after I trimmed the edges and pulled the protective plastic.

And yet another shot of the initial landing light lens test fit.  Note that I beveled the edges of the lens for a better transition to the surrounding nose.

“Better transition for what?” you might ask, since there are clearly mounting screws. Well, see the rivets and lip under the screws?  Sure I could paint that and make it look a little better, but it would still need a good bit of cleanup around the edges and I just never liked that transition from lens to nose.  Maybe someday I could machine or create a nice aluminum flange, or perhaps even maybe a glass or carbon fiber one, but for now I wanted something that would be fairly quick, fairly easy and really make this landing light lens look like it’s integral to the actual nose.

So I decided to glass the edges of the lens, overlapping onto the nose, in a quasi-permanent lens install.  First, to both help seal the edges of the lens from water getting in and to help keep the areas in between the screws from flaring out (“oil canning”), I siliconed the lens to the nose before securing it with the screws.  I then applied Gorilla duct tape as tightly as I could to keep the sides of the lens pressed as tightly against the nose as possible.

After my nose-mounted landing light lens shenanigans, by this point the BID layups had cured and I could press forward on the RAM air scoop install.

I started by trimming first the aft part of the center opening, then some of the forward channel, of the hell hole hatch cover to allow the RAM air scoop to settle into place.  This took nearly a dozen small rounds of cutting, sanding and shaping.

Voila!  The RAM air scoop is now fitted into the hell hole hatch cover.  I will say that somewhere in this fitting “transaction” I lost, or rather gained actually, about 1/16″ in the gap between the front edge of the RAM air scoop and the aircraft belly (now glass base).

My acceptable gap between fuselage bottom and RAM air scoop inlet was to keep it between 3/4″ to 1″, but I was shooting for 0.75″.  Since I first started installing the RAM air scoop that number went from my targeted 0.75″ up to about 0.87″.  Not bad.

Again, with this latest round of actually installing/integrating the RAM air scoop into the hell hole hatch cover, that gap is now 0.95″.  Clearly still within my targeted range and I’ll take it any day of the week!

Here we have an aft view of the RAM air scoop fitted into the hell hole hatch cover.

The next step was to physically attach the RAM air scoop to the hell hole hatch cover. I started this off by laying up ply #3 over the cured initial 2 plies of the RAM air scoop base, that extends forward off the front of the original hell hole hatch cover.

I went ahead and peel plied the front area that will sit underneath (as situated, technically above) the overhanging RAM air scoop.  Also note that I wet out the BID that crosses over the scooped divot in the fuselage (light blue arrow) so that when I set the RAM air scoop into place it pressed up tight to the bottom of it (again, as situated, technically top edge).

I then added a flox fillet on each side on the forward area of the RAM air scoop interface with the hell hole hatch cover opening.  Toward the aft end where the gap was much larger, and it was essentially attaching glass to foam, I used thick micro to fill the gap and create a fillet [Note: I had considered using pour foam on the aft end, but I had no way to create a dam underneath to keep the foam out of the hell hole innards, so I opted for fairly dry micro instead].

I then laid up 2-ply BID tapes along each side and around the aft end.  On the forward side, these BID tapes overlapped onto BID ply #3 by a good 6″ each side.

Here we have the RAM air scoop mounted and integrated into the hell hole hatch cover
—finally!

Another shot of the mounted and glassed RAM air scoop.  Note that I did peel ply these layups.

One last shot of the mounted RAM air scoop.

Finally, after a couple of hours for the silicone RTV to set and cure a bit, I pulled the Gorilla duct tape from the nose landing light lens… so far so good!

And with that, I left the glassed/floxed/micro’d RAM air scoop to cure overnight.

I didn’t get much done on the build today as I ended up watching my little buddy for a good portion of the day.

I was able to determine the general configuration of the RAM air scoop base, or mounting flange if you will, and then taped off the bottom of the fuselage as a mold release forward of the hell hole hatch cover.

I then laid up 2 plies of BID.  The first ply partially overlapped onto the bottom face of the hell hole hatch cover for about an inch on the inboard edge (look at black “L” shaped lines at front edge of cover) while the majority simply abutted the front edge of the cover.

The second and final ply (this round) overlapped onto the front edge of the hell hole hatch cover a good 1.5″ and then covered the same remaining area as ply #1.  I then peel plied the layup and left it to cure.

A good 5 hours later I pulled the peel and separated the 2 plies from the duct tape mold release fairly easily (no repeat of the RAM air scoop flange!!).

I was going to remove the cover and glass a ply of BID at the inside seams between the hell hole hatch cover and this new RAM air scoop mounting base (note the strips of 2″ peel ply along the front edge of the hell hole hatch cover, on the underside of this 2-ply layup), but the glass seemed a bit soft and looked like it needed another good 2-3 hours for a fuller cure (I used fast hardener).

Thus I simply left it to cure overnight and called my work day done.