I started off today by removing the bottom cowling and finally pulling the peel ply and cleaning up the left inside bottom cowl exhaust pipe clearance depression CF layup.  Now this task is officially done.

Before removing the bottom cowling I had outlined the right inboard exhaust pipe at the elbow, which is where a clearance issue still exists between this area of exhaust pipe and the bottom cowling.  I have double and triple checked all the other exhaust pipe-to-bottom cowling clearances for all the pipes and the rest are good.  This is the last bottom cowling clearance issue that I need to resolve.

I’ve pondered over the last few days of how I was going to resolve this right aft/inboard exhaust pipe clearance issue with the bottom cowling, even considering cutting the pipe and angling it upward a bit, but finally decided to work the cowling vs the exhaust pipe. I’m gong to plagiarize here and copy Klaus Savier’s design for bottom cowling exhaust pipe clearance by creating a slash-type bumpout with a sharp angle along the edge… specifically along the lines of the inboard slash-type bumpout shown here.

With the bottom cowl off I determined what was a straight line for the sharper vertical edge of the clearance bump by going off the leading edge of the bottom cowl, which I assessed as near to exactly perpendicular with the aircraft centerline.  After marking the outboard straight cut line on the inside of the cowling, I then drilled a tiny hole at each end of the line and pressed rivets into the holes.  I then flipped the cowling over to draw a straight line between the rivets for my proposed external cut line.

I then temporarily remounted the bottom cowling to check my cut line to see if it was actually straight and parallel with the aircraft’s centerline.  It looked fairly straight, but being on a curve it looked like it leaned out a bit.

I set up the laser level and with the laser line hitting the two rivets I determine the laser level was 16.75″ away from the center of the prop hub (pic 1).  I then placed a clamp sticking outboard at F22 and dropped a plumb bob at 16.75″ out from F22’s centerline.  I then lined up the laser line by moving it a smidge so that it hit the two rivets and the far plumb line (pic 2).  I then marked the straight laser line with dashes between the 2 rivets.

Fun with geometry!  Although the starting and ending points (the rivets) are in the same spot, a straight line over this curve is just a hair off from my original “straight” line (the solid line).

I started to use a piece of tape to mark the cut line, then just said ‘screw it’ and simply used the tape to cut the line.  Now, before I cut out the clearance hole I used a multipoint shape tool to capture the curve to make a template of the outside vertical edge (“smile”) of the clearance bump/divot.

I’ll note that the house next door to me was owned by an elderly couple that very occasionally would come down to stay for short lengths.  They sold it to some people who are now living in it full time, so I don’t want to make crazy loud noises now when it’s late at night.  Since I needed to run to Home Depot, which is 45 minutes away, I wanted to get this loud cutting done so I wasn’t doing it later in the evening.

That all being said, here is the right side inboard exhaust pipe clearance cutout on the bottom cowling.  Again, to mimic somewhat how Klaus has his bottom cowl exhaust pipe clearance bumps.

I then ran out to Home Depot in my quest for 1/16″ Plexiglas for the wing light lenses, which they had listed as in stock on their website.  Well, it was in stock but it was made for picture frames and was somewhat translucent with objects only closeup being clear.  I then ran to an arts and craft store and they only had 2mm (0.078″) thick acrylic in stock.  No joy.

When I returned home later in the evening, I spent about an hour cutting out the clearance bump/divot’s outside vertical edge (“smile”) template from scrap cardboard and creating the other horizontal part of the mold as well… assessing how I was going to do this layup the whole while.  I had planned on using the vertical cardboard template as part of a mold to layup the outside plies of CF first for this clearance bump/divot.

I then realized that the cardboard was too weak: not as a form, but in getting it as a free standing form to attach securely to the bottom cowling for the layup.  It became clear rather quickly as I started my attempt to make a form on the bottom cowling that I needed to transfer the cardboard template to thin plywood.  And it was way too late to start that, so I kicked that can down the road until tomorrow…

So I closed up shop, went inside and did some more research on cast vs extruded Plexiglas… and then spent a good bit of time looking for vendors that had that darn elusive 1/16″ acrylic/Plexiglas in stock!

Moreover, in case I don’t get a blog post in tomorrow: Happy Thanksgiving everyone!

This blog post covers yesterday and today.  I had some personal stuff to do as well as a number of build related phone calls and research to do.

I started off the day with a conversation with GRT Avionics regarding compression fitting EGT probes to ensure that if I needed to go that route I could integrate the ones they sell in with my current set of probes.  As I thought, I can with no issues.  I also asked them how I would go about actually and specifically mounting their compression fitting EGT probes to my pipes: the bottom line is that I would need to acquire/provide a 1/8-NPT female threaded bung/fitting to then weld onto the pipe to secure the compression fitting EGT probe into.

I also asked Nick Ugolini what thickness of aluminum he used for the wing light mounting plate, to which he replied that it was very thin, about 0.015″ thick… obviously to save weight but also since there is no major stress on the mounting plate from these thin, lighter-weight light assemblies.

I was out and about picking up some hardware to test out on these light assembly brackets when I got Nick’s above reply.  I then pondered on it more as I ran my errands —including picking up the light lens plexiglass/acrylic at Lowe’s (they only had 0.080″, so I’m going to try Home Depot and/or some other places within the next day or two for some thinner 0.065″ plexiglass)— when it occurred to me that I might just press forward with using ABS plastic for the lens light mounting plates/brackets.  Hmmmm?

When I got home I started doing research on the best ways to heat and form plexiglass, as well as brushing up on my Fusion 360 CAD modeling kung-fu skills in creating hexagon grids for what my current mentally-pictured bracket looked like.

Now, Fusion 360 is obviously a powerful CAD/CAM/modeling program, but I equate it to a lot of other technical skills… very perishable.  If you don’t do it often your skills definitely atrophy.  Moreover, seemingly simple tasks like adding a side grid of hexagons shouldn’t be that difficult, but it took me deconstructing the info in about a half dozen videos and then over 2 actual hours to hamfist my way through.  But I figured it was another good tool to have in my CAD toolbox, so I “wasted” a few hours in figuring it all out.  Here’s the result after a nearly 3 hour print:

I put 0.6″ deep sides on the wing light mounting plate to reinforce the plate.  I guess now it’s more like a “bracket.”  Whatever you want to call the darn thing.  The hex grid is to ensure cooling air is free and unhindered to the light cooling fins, as well as to significantly lighten up the bracket of course.

And here’s a side shot of the hex grids on the new version of the wing light mounting bracket.  My plan is to make up a final version of this bracket and then machine an aluminum mounting plate to see if there is any significant weight difference, and then press forward from there.

If you’re wondering, Nick already did the heavy lifting on the heat generated by these lights inside the small leading edge wing pocket by doing a multi-hour long burn-in session with the light in the wing pocket and the lens taped in place.  He noted with the LEDs it was a bit warm, but nowhere close to any issue with high heat.

I also queried Nick on the steps he used to heat, mold and create the acrylic lenses.  He replied that it had been so long ago that I should ask Chrissi and Randi (AKA “The Cozy Girrrls”) about it since they just did this fairly recently.  So I did.  That kicked off about a 1.5 hour long phone call with Randi, with no appreciable new Intel in hand by the end of the call… although it was great catching up and discussing all things Long-EZ!

Finally, I’ll note that I had a quick discussion with my contact regarding the inner engine baffle forms, and I’m happy to report that they are being shipped to me (I have the tracking #!) and I should have them Saturday.

Now, that being said… for all you foreigners (ha!) this week is our American holiday, Thanksgiving.  Between that, a 2-day out of town trip and an airshow/dinner evening out, I’ll have quite the social calendar going on over the next 4-5 days.  I do plan, however, on getting what I can done on this bird when I can during that timeframe.

Pressing forward!

Today was all about the initial big push to get the aft engine baffle templates dialed in for my engine in prep for when the inner baffle forms arrive and I get those knocked out and installed.

I started on the left side and cut Mike Beasley’s “Beasley Baffles” template at the long corner edge of the upper “shelf” section and the lower “skirt” section.  I used the upper shelf section as is and trimmed it to fit.

On the lower skirt section I made a copy of the original template on a large piece of poster board and then used that to make my template on my engine.

After I dialed in the left side top shelf section and the bottom skirt section, I simply taped the 2 pieces together.  All in all, with the constant iterations of putting the templates in place, marking, trimming, putting back in place… rinse and repeat… it took me well over 2 hours just on that part alone.

But I am definitely much, much closer to a finished product, albeit with a myriad more tweaks and trimming left to do.  This is merely the first stab at getting an initial workable template for the aft baffle segments.

I then repeated the same thing on the right side.  Again, this took a good couple of hours to do the initial skirt baffle copy and then slowly dial in the shape and form of the right aft engine baffle.  Note that I actually had a little help on this side with the screw hole in the #2 cylinder head.

Here’s a shot of the engine aft baffle “shelf” sections.  I’ve seen this baffle style in a lot of pushers where the aft corner edges of the shelves match, even though clearly the right shelf —with the cylinders positioned forward— is much wider than the left side.

The area beneath the flywheel, around the alternator and starter, is typically much wider, deeper and bowl-shaped on other Long-EZs than the “V” shape that the Melvill cowling has… regardless, it all seems to fit so I’m happy with it.

And here we have both poster board/thick paper aft baffle mockups in view.  I really like the way this will look when completed.  That being said, I have to note that both sets of exhaust pipes are kicked out a hair more than they will be when all the component installs are final.  Thus clearly why I’m dialing these aft baffle templates in with poster board so I can tweak, modify and dial in as required.

To get an idea (for me and you!) of how this will look with both the spinner flow guide and upper cowling in place, I went ahead and temporarily put both in place.  As each step progresses and each task is completed on this engine area, I’m more and more pleased with how it’s all turning out.  It honestly was not a fun first half of this year figuring and working it all out.

And with all that good feeling talk, I should note that I’m going to have to make a significant cowl bump on the RIGHT side bottom cowling under the horizontal elbow of the right inboard/cylinder #2 exhaust pipe.  It’s just too close to the inside corner of the bottom right cowling.

These pics give you an idea of what I’ll be looking at during pre-flight when I check out the alternator and belt on the left side and the starter on the right side.  Yep, even though the cowlings are very tight around this engine, I still have good visibility to check on these components pre-flight.

I had texted Nick Ugolini earlier in the day that I was ready to discuss the wing light forms that I received from him (as well as a slew of pics).  We agreed to discuss my wing light install later in the evening.  Well, perfect timing on Nick’s part because he called tonight just as I was just winding down in the shop.

Nick and I were on the phone for well over an hour discussing primarily his how-to steps on installing the outboard wing landing and wig-wag lights.  In addition, we spent a good little bit talking about baffling and engine cooling.

If you’re not familiar with the outboard wing leading edge lights, here’s what they look like when the install is complete:

Although it was late, my curiosity got the best of me and I measured up one my AeroLEDs “Recognition/Landing Light Assemblies” to model up a light support bracket for mounting into the leading edge of the wing.

I then of course did a quick 3D print of the wing light bracket.

Thankfully my numbers were correct, and the light fit like a glove in the 3D printed test light bracket.

And a bit closer final look . . .

Like I said, it was late… so with an unplanned task knocked out, I hit the rack.

Today was primarily about getting the exhaust pipe EGT probes positioned and installed, but first I pulled the peel ply off the bottom cowl left side outboard exhaust pipe clearance depression 2-ply CF layup.  It looked great, so I moved to the inside…

Where I pulled the peel ply on the inside of the divot that I created on the left side of the bottom cowling for the #3 cylinder exhaust pipe clearance (I forgot to grab any pics of the ensuing 1-ply CF layup and peel ply on the inside bottom cowling, but you can catch glimpses of it in the pics of the cylinder #3 exhaust pipe EGT probe immediately below).

I spent well over 2 hours in my final research on EGT probe position (facing inboard or outboard?), placement (how far from exhaust pipe flange?) and any other general tips and/or tricks that I could find.

If possible, EGT probes should all be equidistant from their respective exhaust pipe mounting flanges to all be reporting their equivalent heat value at the same distance from the heat source (aka “the exhaust port’).  Makes sense.  That being said, I also noted the oft warning of having the EGT probes mounted too close to the exhaust flange/port and risk literally getting burned up, drastically reducing probe life.  The sweet spot reportedly is around a 3″ EGT probe position from the exhaust mounting flange, which is inline with GRT’s recommendation of 2-8″ as denoted in their EIS install manual.

It took a good half hour to find a compromised sweet spot between all the exhaust pipes, the aft cylinders being the odd ones out requiring special attention here.  The common EGT probe install position/distance I settled on for all cylinder exhaust pipes was 2.65″ from exhaust flange face to EGT probe hole.  For added measure I’ll throw in a swag of +/- 0.15″ max… but probably more like +/- 0.07″ in reality.

Here we have the left outboard/cylinder #3 exhaust pipe EGT probe hole drilled (pic 1) and installed (pic 2).

And here on the right side, we have the inboard/aft cylinder #2 exhaust pipe EGT probe hole drilled, with the EGT probe installed on the outboard/forward cylinder #4 exhaust pipe.

Here I’ll quickly note another oft-cited warning that various homebuilders provided: ensure not to block access to installing or removing the bottom spark plugs.  Yes, good thing to watch for!

Again, the aft cylinders needed some special consideration not just in the distance between the exhaust pipe flange and the EGT probe, but also in the clocking of the probe —which I really haven’t touched on yet, but was a significant consideration for each individual probe— not only in regards to what angle the EGT probe body was protruding from the exhaust pipe, but specifically the placement of the securing hose clamp screw assembly.

A perfect example of what I’m talking about is the right inboard/cylinder #2 exhaust pipe: if the hose clamp screw assembly is positioned forward, approximately 90° from the EGT probe (as they all are; standard position) as in pic 1, then it results in diminished clearance for that exhaust pipe as a whole with the bottom cowling as you can see in pic 2.  Since I have just a hair under a 1/2″ worth of clearance between cylinder #2’s exhaust pipe and the bottom cowling, clearly the hose clamp screw assembly in this position diminishes that clearance greatly and is an outright no-go.

The problem then potentially becomes about as much of a pain in the keister as well if I place the hose clamp screw assembly 90° out on the other (aft) side, since it starts clogging up the access to remove or install the #2 cylinder bottom spark plug [Ah, which I was warned to watch out for!].  But I will note that I didn’t test out this possible clearance issue, but will tomorrow….

Yep, I jumped the gun on checking clearance for the left inboard/cylinder #1 exhaust pipe EGT probe by mounting the bottom cowling in place, so again I’ll have to check spark plug removal/install clearance on cylinder #2 tomorrow.

That being said, here we have the EGT probes installed on the right side exhaust pipes.

One last note on the possible clearance issue with cylinder #2 spark plug removal/install and the exhaust pipe EGT probe hose clamp screw assembly… IF that proves to be an issue the fix would be installing a compression fitting style EGT probe.  That would require welding in a threaded port at the EGT probe position on the exhaust pipe, then sliding the EGT probe in position and threading in a securing cap that is pre-installed around the EGT probe assembly.   I would of course need to order this type of EGT probe from GRT:

Additionally, if possible I wanted each cylinder exhaust pipe EGT probe to face inboard towards the engine to allow for better routing of the EGT probe wires.  Being very low voltage signal wires I wanted these EGT probe wires as far away and not comingling with the much higher powered spark plug wires in any fashion.  However, I was only able to face the #1 cylinder exhaust pipe (aft left) EGT probe inward, with all the remaining facing outboard.

And as it just so happens, the final EGT probe I installed was on cylinder #1.  Again, I didn’t want the EGT probe hose clamp screw assembly facing downward since this would eat up exhaust pipe clearance with the bottom cowling.  On the top side I didn’t want the hose clamp screw assembly too canted inboard since I didn’t want any ensuing clearance issues with the cylinder fin baffles that will go in this area.  In short, I wanted the EGT probe hose clamp screw assembly situated squarely on top of the exhaust pipe, with the EGT probe itself facing inboard and positioned slightly downward… pretty much just like it’s shown here:

Here we have the EGT probes mounted into the left side exhaust pipes.

Finally, as I prepared to close up the shop for the evening, I went ahead and set the top cowling in place to check out the positioning of the left exhaust pipes in the aft cowling opening.  Pretty not bad IMO!  The pipes of course need to be trimmed in length and their final openings will both be about 1/2″ inboard (right in pic).

And with that, I called it a night!

I started out today by removing the bottom cowling, then spending a fair bit of time assessing and evaluating just how and where I needed to cut the left outboard exhaust pipe to get the aft half into its proper position.

After finally deciding where I needed to cut it and on what angle, I marked the cut line.

I then removed the left outboard exhaust pipe and ran a piece of tape with the edge at the center of the cut.  I then marked the angle on each side of the center cut line that in my estimation would bring the aft end of the pipe down close to level with the front end, and allow it to pair up decently with the inboard exhaust pipe.

As you can see below, I then carefully cut the pipe on the angled lines off the marked center cut line.

I then taped the left outboard exhaust pipe pieces tightly together at the cut… Voila! Pretty darn close to where I wanted it!  To be fair, I was trying to get it about an 1/8″ higher so this pair of pipes would be angled more like the right side pipes.  But no worries, this will work!

As a reminder, this is close to what it looked like when I started.

And a side shot of the cut and tape re-joined left outboard exhaust pipe.  This definitely meets my overarching goal of getting the pair of left exhaust pipes positioned at the correct elevation inside the cowlings and somewhat closely nested together.

And again, this is what the pipes looked like just before I made this cut.

I also took the opportunity tonight to add a little depth to the bottom cowling at the point where the left outboard exhaust pipe first major bend is closer to the cowling… at the hash-marked area.

I cut out the hash-marked area with the Fein saw.

Now, the key to understanding what I’m doing here —very hard to show in pictures— is that there is an upward indention from the outside of the bottom cowling from where I reworked the aft half of the bottom cowling.  This creates a bit of ridge on the inside of the cowling, which is right beneath the initial bend of the left outboard exhaust pipe.  I’m essentially removing that inside cowl skin ridge and flattening it to get a good 0.1″ minimum added clearance for this area of the exhaust pipe…. probably a hair more than 1/8″ in total clearance.

Also, if you look closely on the aft aluminum vane outboard edge you’ll see a Sharpie mark (pic 1)… this is the edge that needs to be trimmed just a hair (also for clearance with the left outboard exhaust pipe), which I did with the Dremel tool and then cleaned up the edge with some files (pic 2).

I then prepped the exhaust pipe clearance hole in the bottom cowling for a layup.  I measured and cut 2 plies of CF, prepregged them, and then laid them up with some MGS epoxy.

I then peel plied the exterior side of this 2-ply CF layup.

And also the exposed CF layup on the inside of the exhaust pipe clearance hole.

Tomorrow I’ll pull the peel ply, smooth out the edges of the existing cowling surface around the new CF layup, and then layup a ply of CF on the inside of this bottom cowl exhaust pipe clearance layup.

I’ll most likely get the outboard exhaust pipe welded up either Monday or Tuesday, so between now and then I’ll get to work on some other stuff!  Pressing forward . . .

Today was another exhaust pipe welding day.  I loaded up my vehicle and made the hour trek to James’ shop to the get the inboard left exhaust pipe for cylinder #1 welded up.

As I said in yesterday’s blog post, this was a 2-weld job since the exhaust pipe at this point was in 3 segments.  Here’s a shot of these segments on James’ workbench ready to be welded up.

And here is the inboard left exhaust pipe —both sides shown— many hours later back in my shop after James’ excellent job of welding it up.

The sharper initial curve angle, that I had discussed with both James and Clinton from Custom Aircraft Parts (original builder of these exhaust pipes), is required for clearance of the pipe off the bottom cowl.  It looks even sharper because the curve on the original exhaust pipe continued downward for a good 1/4″ or more before coming back up level… that’s why that small segment of straight pipe had to be welded into place at a sharper angle: to replace the downward curved section.  The angle will have negligible, if any, negative impact on the exhaust flow.

Here is the freshly welded left inboard cylinder #1 exhaust pipe mounted in place on the engine.

And here’s a shot of that pipe from below… the sharp bend now being the low point vs the pipe segment 2-3″ aft of that bend.

I then put the bottom cowling back on to check the elevation of the welded left inboard exhaust pipe compared to what I was looking for.  As you can see, the pipe is just kissing the wood spacers that I had taped in place for where I wanted the aft pipe edge to be (pic 1).  I then removed the wood spacers to show the gap without them (pic 2).

I then spent another hour assessing both the clearances between all the pipes and the bottom cowling and EGT probe positions.  In addition, I also assessed what needs to happen now with left outboard pipe to angle it down and inboard to nestle it in with the inboard exhaust pipe.

On clearances: I decided I won’t need the significant bump out or divot in the bottom cowling for the outboard left exhaust pipe as I thought, since it sits right on the seam from the old cowl surface to the new cowl CF that I reworked.  By just reworking the seam I should get about another 0.1″ of clearance without have to make any notable bump on the exterior side of the cowl.  However, the initial elbow on the right inboard exhaust pipe is even closer than this cylinder #3 pipe, so I will need to flush that out and assess further.

At this point my brain was hurting from so much thinking, so I called it a night.

I started off quickly brushing on a couple rounds of flat clear coat to the areas I hand painted around the GIB headrest & D-deck gap cover… to get that knocked out.

Actually today was all about getting the left inboard exhaust pipe mating surface trimmed at the proper angle to seat against the 90° elbow portion of the exhaust pipe that is bolted onto the cylinder #1 exhaust port.

This is one trimming session of 3 total that I did, after a good 10+ minutes of assessing height, angle, standoff from spinner flow guide, etc. in between each round of trimming.

Here we have the final trim of the left inboard exhaust pipe.  After I dialed in the angle and position, I texted James to see if he would be available tomorrow to weld this up.  I’ll note that there are actually 2 welds that need to happen here, since under that ring of black tape is another spot where the pipe is cut in two.

BTW, James did say he was available so the plan is to get this exhaust pipe welded up tomorrow… Hoo-ah!

After another 45 minutes assessing the exhaust pipes and upcoming aft engine baffle construction, I closed up shop and headed out to dinner with Jess to relax for a bit.  Just before dinner I finally picked up some #6 SS hex button head screws for the GIB headrest & D-deck gap cover.

Upon my return home later, I mounted the GIB headrest & D-deck gap cover with the screws I had just acquisitioned a few hours earlier.  Here’s how it all looks.  Not too bad, in my opinion!

And some closer up shots each side.  Can you pick out the areas that were hand painted?  Hopefully not!  I do need to still do some minor sanding and tweaking around the edges, as well as fix the rough edge on the one side… but overall?  I’m pretty darn pleased with how it turned out.

I then spent a good half hour plus removing the tape and cleaning off the gunk, as well as cleaning up the mating edges of the different left inboard exhaust pipe pieces in prep for them getting welded up tomorrow.  I then called it a night.

Today was the day I FINALLY kicked off my long-overdue exhaust pipe welding plan with James.

But first I pulled the heat lamp off the CF layup on the right side cold air induction pipe bump, and then pulled the peel ply.  I then cleaned up all the peel ply boogers.  As you can see, there is still a very slight bump from the original bump in my added foam fairing, but I will mitigate that with both some aggressive sanding and added micro when finishing.  Overall, not bad and definitely does the job in both adding needed clearance for the aft right cold air induction pipe, and not creating a heinous goiter on the side of the bottom cowling.

While the bottom cowling was on, I remembered to grab a shot of the newly angled aft oil cooler exit.  Not crazy distinct in nature here, but definitely a significant angle created.

I then did a very final assessment on the left outboard (cylinder #3) exhaust pipe position before pulling a good bit of the duct tape off the pipe that was securing the cut exhaust pipe to the engine-side elbow.  I then marked the position as best possible across the hose clamp.

I then removed the bottom cowing and both left exhaust pipes from the engine.

Now, with that duct tape on there for a LOT of months, it required about 30 minutes more than I was planning on to get it off there and cleaned up.  Cleaning all the tape gunk off the exhaust pipe made me a bit later getting to James’ home shop than I had planned on, but all was good (I’ll note the drive from my place to his is right at about an hour).

After we bantered about a bit on the exhaust pipe welding plan, airplane homebuilding and military war stories, James dove right in on welding up the first weld on the cylinder #3 exhaust pipe.  Again, this is James’ home shop and I noted right off the bat that this guy —who welds up race car exhaust headers for a living— has the exact same TIG welder in his home shop that I do!  That made me feel like I’ve made at least one right decision along the way… ha!

Here’s James’ beautiful TIG weld on the cylinder #3 exhaust pipe.  Note the pink cap… the other end of the pipe is capped as well and is flooded with inert gas on the inside as the pipe gets welded.  This creates a strong, clean, porous-free weld.  Again, even if I was inclined to tackle this welding, I would need a setup like this to do it (we’re talking a decent bunch of $$$ for essentially a one-time task).

As James was welding up the pipe I of course was not directly watching what he was doing with no welding helmet on, so I wandered around his shop a bit.  James has a huge Grizzly bandsaw in a central location along the wall of his shop, but over in the corner he had this smaller Grizzly bandsaw.  Since my small Skill bandsaw has never been a top performer, I noted this G0948 model in the corner and thought that it looked like a perfect size for what I need, since I honestly don’t do a ton of bandsaw work.

As we were talking after James finished welding up the exhaust pipe, I asked him how he liked this smaller bandsaw in the corner.  He said a friend of his bought it new, never used it, gave it to him and it’s sat in the corner unused for 2 years now.  He offered it to me for a steal, practically giving it to me, and I of course couldn’t refuse (remember, I’m cheap!)… so into my vehicle it went.  Hopefully my bandsaw woes are behind me now! <grin>

From James shop I drove into town and spent some time there, grabbed a bite to eat and then finally got home later in the evening.

I mounted the freshly welded #3 cylinder exhaust pipe onto the engine, and it looks great.

I then mounted the bottom cowling into place.  Here we have the clearance between the armpit intake aft ramp/vane with the #3 cylinder exhaust pipe without the tape and hose clamp in place.  I plan on trimming about another 1/8″ off the outboard edge of the vane, and then we’ll be good on clearance.

This shot here shows the area I was most concerned about on this round of welding up the #3 cylinder exhaust pipe.  I wanted to get the pipe as high off the bottom cowling in this area as possible.  My measurement on the aft side of the pipe (right side of pic) was 0.7″ from the exhaust pipe to the 3rd fin in on the aft bottom corner of the #1 cylinder.  When I measured it here that gap was 0.65″… perfect!

I’ll work the left inboard pipe next, and get it welded to its bare elbow sticking out of cylinder #1.  After a round or two of welding on the inboard left exhaust pipe, then I’ll come back to the outboard pipe again and get it situated.  Note the approximate distance from bottom cowl to where the bottom pipe end opening edge should be… about at the top of the wood spacers.

Here’s a better look (sorry for the fuzzy pic)… you can see right about where the outboard pipe meets the starting elbow of the inboard pipe is where it will need to get turned downward and slightly inward.

This pic shows that even a bit more… I set the inboard pipe loosely in place, close to its final exit elevation.  See how the outboard pipe will need to get angled down and inboard a bit?

And a shot of this with the top cowl in place, which really shows you what machinations need to take place to get these left side exhaust pipes wrangled into place.

But how do we eat an elephant?  One bite at a time!  And that is exactly how these left side exhaust pipes will get configured into the final positions they need to be.

Pressing forward!

I started out today by doing a final sanding in the area around the bottom cowling right side bumpout that will provide needed clearance for the aft cold air induction pipe.

I then made up a pour foam dam in preparation for the foam.

Since this part of the cowling is on a curve, and any liquid —including pour foam— seeks a level plane, I needed to use a bit more pour foam than I would have wanted to.  It’s hard to judge on this stuff sometimes, and I definitely wanted a bit too much than too little… and that’s what I got.  I didn’t want any pour foam seams here.

I don’t have any shots of it, but last night I dabbed on some coats of primer on the hard-to-reach unpainted areas around the GIB headrest and inside turtledeck.  During this half hour waiting period for the pour foam to cure, I sprayed some gray rock paint in a cup, added a little bit of micro to thicken it while also adding a little bit of Acetone to thin it (yes, these may seem like opposing actions, but it needs both to still be a pain to apply with a brush).  I then added a sloppy coat of the gray rock paint over the previously applied primer.

I also contacted my welder James and let him know that I was ready to kick off our exhaust pipe welding adventure.

I then got back to work on the bottom cowling right side cold air induction pipe clearance bumpout.  I trimmed off the front and aft peaks of the pour foam before pulling off the dam.  Although I had way more pour foam than I needed, at least it was a good pour and an all in one go.

I then spent the next half hour removing nearly all the pour foam: trimming, sanding and shaping it down to just even with the CF bump I made yesterday.  I then sanded and Acetoned the edges and vacuumed the foam in prep for a ply of CF.

I then made a quick plastic sheet template of the foam shape to cut out both a ply of CF and a piece of peel ply.

I then whipped up some Pro-Set epoxy, wet micro’d the foam and laid up the 1 ply of CF.

I then peel plied the layup.

I then applied another coat of blotchy grey rock paint (this stuff does NOT like going on with a brush) around the GIB headrest and inside turtledeck, and then cleaned up my paint project before heading into the house to upload these pics.

About an hour later I went back out to the shop and mounted the bottom cowling on the bird. I then spent a good 20 minutes assessing the final position for the outboard left (cylinder #3) exhaust pipe.

Since the nights are getting much colder here now, I also put a heat lamp on the layup just to maintain a decent level of warmth overnight.  I then left it to cure overnight.

Barring any curing issues, this pretty much completes the task of creating clearance for the right aft cold air induction pipe.  That leaves 2 final major tasks on the bottom cowling:  1) a clearance bump on the left side bottom cowling for outboard/cylinder #3 exhaust pipe, and 2) a cross rib baffle/stiffener once the lower aft baffling is in place.

And with that, I called it a night.

Although I started out today working on the GIB headrest-to-turtledeck gap cover, I ended my shop time working again on knocking out some final bottom cowl tasks.

Yesterday I used a big sheet of yellow vinyl to place the single ply of laid up CF face down on, then weighed it down with a myriad of stuff: steel sheets, wood blocks, cordless drills, and epoxy cans to get the flat, even surface of finished CF… without a rough peel ply texture nor an even rougher, bumpy no-peel ply natural cured finished.

I had concerns with how the CF weave would turn out when I flipped it face down.  With a decent amount of excess epoxy to ensure the surface would come out smooth, the epoxy grabbed the vinyl a bit and pulled on the just laid up ply of CF and ended up putting a bit of a wave in it vs the straight diagonal line I was shooting for.

Moreover, when I pulled all the weight stuff off and then the cover off the yellow vinyl this morning, somehow there was an actual strip of the layup that didn’t get weighed down properly.  See the outside right edge about middle of the pic below?  What the…? BTW, clearly these pics were taken after an initial razor trim of the CF layup.

Since this was my first time attempting this type of flat, even-surfaced CF layup, to bring about this finished look post-layup —without multiple rounds of applying epoxy or clear coat with even more multiple rounds of wet sanding— I had a backup plan with some CF vinyl ready to apply over the top of this in case it turned out bad, or as Jess jokingly calls things, “an actual turd!” (usually houses on Zillow!)…  which at first I thought the CF on this cover turned out to be.
[Note: this was also a test run for this type of layup that I may employ on the more visible inner cylinder baffles to make them look as sexy as possible <wink>]

I still needed to shape the edges and get it mounted back in the gap around the GIB headrest, regardless if I was going to cheat and use the CF vinyl that was now in the shop and ready to be pressed into service.  However, once I got the the cover in place —a good hour of test fitting, trimming/sanding, repeat— the weave honestly wasn’t horrible (or an actual turd! haha).  Mainly because the slight curve of the weave is fairly symmetrical, at both left and right “upper corners.”

The cover is far from perfect, but it clearly does its job in covering the unsightly fuel vent lines behind it, and the weave of the CF while not straight and factory finish looking is real and a product of my effort, so I think I’ll fix the blemished edge and call it good… AKA: this dog will hunt!

Below are closer up shots of each side… not a perfect edge in getting the CF trimmed and sanded down for the cover to fit back into place, BUT it will not hinder the airplane from flying, makes this area look 10x better, and has a nice contrast… so again, I’m pressing on to more important tasks on this bird!

One final point of note on this cover: Yes, it’s cosmetic and in no way would hinder me from flying this airplane in any way.  So why create it now when there are so many important flight-related tasks that need to be completed?  Because, analogous to wheel pants, if I didn’t complete this now I’d be flying around for a good 6 months to a year+ with an unfinished, unsightly cabin component with me constantly saying, “Oh yeah, after this next trip I need to get around to doing that…” Nope! I want to get these seemingly small, time-busting innocuous things out of the way now and off the plate for good (Seriously, you’ve all seen this on peoples’ builds… especially with getting planes painted and out of primer 3-4-5 years after they’re flying) .

One of the half-dozen “final” tasks I have listed for the bottom cowl (not including finishing and painting) is something I never got around to after re-skinning the aft half on each side of the bottom cowl: sanding the newly laid up CF surfaces.

I took the bottom cowling outside and spent a good 45 minutes sanding down the lumpy and bumpy new-ish cowl surfaces with my DA sander.  Again, I didn’t sand the surface to 100% perfection, but I’d say a good 80% of the major lumps and divots were smoothed to greatly minimize the amount of micro fill required.  I also sanded the inside as well just to eliminate any roughness or peel ply lines in prep for laying in the bottom cross cowling rib baffle/stiffener, and to remove excess material just to lighten up the cowl as much as possible.

Here’s a shot of some my bottom cowl surface sanding and also the cured CF ply over the 2nd generation right side cowl bump to provide required clearance internally for the aft right cold air induction pipe.  Tomorrow I plan on adding & shaping pour foam, then contouring it to blend in as best possible with the lower right cowling before glassing it with a ply of CF.

Lastly, I pulled the peel ply, razor trimmed and cleaned up the now angled aft edge of the oil cooler exit on the bottom cowling.

The bottom cowl sanding and the completed angled oil cooler exit aft edge are 2 tasks off my bottom cowling to-do list.  Once I complete the right side bump-out for the cold air induction pipe clearance, that will be a third task completed.  The last major task on the bottom cowling will be a clearance bump on the left side for the cylinder #3 exhaust pipe.  After that, the final cowl tasks will be on the handful of items that need to be knocked out on the top cowling.

In addition, I plan on starting whole-hog on the exhaust pipes this coming week to get those finished up and configured nicely inside the mounted cowlings.