I started out today by sanding the cured MGS epoxy wipes on the inside surfaces of the air induction tube.  Of course as per usual that took a good little bit of time, but I have to say that these surfaces turned out pretty darn smooth!

My initial plan was to tape each end and completely glass the tube halves back together in between the tape with 2 plies of carbon fiber —one just along the seams and one full ply around the entire tube.  However,  it turned out that I needed 2 extra respective wraps of tape (I used electrical tape) around the curved area of the tube halves to get them even and aligned to each other.

I thus pivoted and decided to simply start down a longer road of getting these induction tube halves back together.  I laid up a single ply of carbon fiber BID overlapping about an inch onto each respective tube on each side of the split and then peel plied the layups.  As you can see, that resulted in 3 layups per side of the induction tube.  I’ll note that I used MGS epoxy with fast hardener.

To ensure my ID was pegged at 2.3″ I cut and taped up (to keep them epoxy free) segments of a pool noodle that just happened to be 2.3″ in diameter… remember, better to be lucky than good!  That being said, that worked well for each end.

Here we have the air induction tube with the majority of the sides rejoined with separate single plies of carbon fiber.  Note how the electrical tape around the “corners” of the curve pulled this area of the curve tighter together.

As a mere point of note, I calculated the differences in circumference vs diameter that I lost about 0.02″ in ID around this curved area from the tape pulling in the halves of the tube more tightly together than at the ends.  Not a big deal, and I figured I would pay some minute penalty for cutting the tube and rejoining it back together… it’s simply the cost of doing business in making these parts.

A number of hours later I pulled the peel ply from the layups and the tape securing the air induction tube halves together.  I then cleaned up the layups.

Here we have the initial rejoining of the air induction tube halves.

I then cut and laid up 2 small patches of carbon fiber BID on each side to fill in the gaps for rejoining the air induction tube halves.  I’ll note that up to this point I have still used nothing but scraps (as in loose pieces not off the spool) of carbon fiber to create this air induction tube.

Since I wanted to keep the original 2.3″ ID of the tube as best possible, I have a gap between the tube halves on the inside of the tube.  To optimize wall smoothness inside the tube, I laid flox into that small gap on each side and peel plied it… about 6″ into the tube where I could reach with a long narrow piece of wood.  I also peel plied the outer gap on the lower front part of the tube.

I then left the glassed and floxed air induction tube to cure overnight.

Today was all about sanding… and more sanding.

And dealing with a technical issue with GoDaddy that apparently was so egregious that they suspended this website… I had 3 backup database files from early 2016 on the root directory of the server.  After multiple phone calls and hours of brushing off an old FTP client to fix the world-ending issue to extricate myself from the geek doghouse, I was once again deemed worthy in their eyes to be allowed to have my website back on the ether!

Remember my rant a few weeks back about geeks and techies?!  Well . . . .

Just prior to me finding out about my near-unpardonable techno-sin, I had finally finished sanding the inside surfaces of each half of the split air induction tubes… around 45 minutes per side.  Overall the inside surfaces were pretty decent, but I wanted smoother: my goal was to take them from a guesstimated 50-60% smoothness factor to 85+% smoothness factor… general made up officious-sounding terms here.

Once sanded, I slathered the holes, divots and imperfections with a concoction of micro + West 410 and set them aside to cure.

I had planned on sanding them an hour or so earlier but then came all the drama with the website hosting.

Returning back to the shop, I spent around 45 minutes a piece (again) sanding the internal surfaces of each air induction tube half.

This round of sanding got the inside surfaces of these suckers pretty darn smooth.

But to take it to the next level and to really seal in the slightly porous surface of the sanded micro, just as with micro finishing the airplane surfaces for paint, I spent my evening hours applying 3 rounds of epoxy wipes to the internal surface of the split air induction tube halves… only here I’m using MGS vs West epoxy for the wipes.

Here we have the first of three rounds of epoxy wipes on the inside surfaces of the air induction tubes.

And with that dear readers, I called it a night.  Hopefully tomorrow I can finally get these bad boys recombined into one tube, eh?!

Today was all about working the Fuel Injection Servo air induction tube initial carbon fiber layup.  As an aside, yesterday I discussed my plan and showed pics of my configuration to Alan Jesmer from Precision Airmotive, to which he noted that he didn’t see any issues with what I had in mind for implementing my air induction system.

I started off by using my Fein saw to trim each end of the air induction tube.  I then sanded the edges of each end.

I then spent a good bit of time thoroughly sanding the exterior surface of the air induction tube initial carbon fiber layup.

I say “initial” carbon fiber layup since I need to split the current tube into 2 halves to first extract the 3D printed plug and internal peel ply, and then sand and prep the internal surface to ensure the air gets as smooth of a ride as possible on its way to the FI servo.

Then I’ll layup at least 2 plies of carbon fiber along the seams when I create a single tube again… one ply which will encompass the entire exterior surface of the air induction tube.  Obviously these last layups will be the “final” carbon fiber layups.

Here I marked a cut line on both sides of the air induction tube.  The reason I’m cutting horizontally along the sides vs vertically down the middle (which I would prefer) is simply to keep the buildup of composite material at a minimum along the bottom center of the tube, which is of course the area that is closest to the inside of the bottom cowling… with the least amount of clearance with said cowling.

I again used the Fein saw to cut down the marked cut lines to split the carbon fiber tube.

Of course I still had a pretty much intact 3D printed tube mockup/plug on the inside that I had to pry apart.  After a good 10 minutes and some judicious destruction, with prejudice (ha!), the 2 tube halves finally came apart.

I then spent well over an hour prying out both the plastic and peel ply from the inside surface of the outer portion of the tube.  You can obviously see the 3D print innards on the other half of the tube….

Which I then tackled next.  It was a little easier than the first half of the tube since it’s essentially an outside curve and I had much more access to get in and remove the plastic and peel ply.  Plus, since it’s the inside of the curve, there is simply a lot less surface area.  That all being said, it still took nearly an hour to extract all the plastic and peel ply from this side of the tube as well.

I had planned on doing a bit more, but I had promised Jess that I would spend an early evening and dinner in New Bern with her, since it was such an uncharacteristically warm day (Yes, SHE is clearly to blame! ha).

Tomorrow I’ll give the inside tube surfaces a good sanding and then fill the holes/depressions with a micro/West 410 mix.  After that cures and I sand the micro fill, I then plan on doing at least a couple epoxy wipes to help fill in any leftover holes, gaps and low spots.  Plus I would simply like to have the inside of this tube as smooth as possible.  After the inside tube surface prep is complete, I’ll then rejoin the tube halves and finish constructing the air induction tube.

I started out today by cleaning up and mounting the 3D printed Fuel Injection Servo air induction tube to allow laying up the initial plies of carbon fiber, essentially turning my mocked up test part into a layup form.

I started out by peel plying the 3D printed air induction tube first, then laying up an initial ply of  carbon fiber UNI, followed by an overlapping ply of CF BID.  I’ll note that all the CF BID I used on this initial layup were scrap pieces.

I then peel plied the initial carbon fiber layup on the 3D printed air induction tube plug.

While the initial air induction tube carbon fiber layup cured, I then cut a piece of tubing —that will make up the SCEET attach point on the front end of the air induction tube— off the foot-long length of 2.5″ diameter 6061 tubing.  To avoid any negative carbon fiber-on-aluminum galvanic reaction over time, I went ahead and wrapped the ~2″ part of the tube that will get attached to the front of the air induction tube with a ply of UNI, then peel plied it.

I then set aside the glassed aluminum tube to cure as well.

I grabbed one the two air induction tube mounting plate 3D-printed mockups and used it as a template to mark up my 1/16″ thick stock of G10… to create the actual mounting plate base.

Which I did here: I cut the marked G10 stock, sanded the edges, radiused the corners, and drilled the 4 corner bolt holes.  I then test fit the air induction tube-to-Fuel Injection Servo mounting plate in place on the servo.  As you can see, it fit like a champ.

A few hours later, after the air induction tube carbon fiber layup was about fully cured, I pulled the peel ply and cleaned up the edges and surface.

Here we have the carbon fiber layup on the right side of the air induction tube form.

And a final shot with the peel ply pulled and the carbon fiber ready for trimming on each end.

Tomorrow I’m going to an FAA A&P/IA training session (I’m neither but was invited by Alan from Precision Airmotive) so I probably won’t get much work done, if any, in the shop.

When I do get back in the shop my next step will be to trim each end of the air induction tube carbon fiber layup, sand it to smooth out any rough/high spots, and then cut it down the middle of each side to extract the internal 3D printed plug from inside, plus the internal peel ply.

I’ll then clean up any areas on the inside of the air induction tube halves that need it before floxing and glassing the halves back together.  After that cures I’ll glass the top Fuel Injection Servo mounting bracket into place and add the 2.5″ diameter 6061 tube to the lower forward edge.  At least that’s the plan.

When I removed the fuel injection servo side air induction tube segment from the 3D printer plate it cracked a bit (more in some spots) and I tried the proverbial super glue to repair it.  That worked on about 50% of the cracks.

Thus, to ensure no future damage and that the geometry stayed fixed as I had modeled it I taped up the tube segment to ensure it would A) stay together and B) not crack further.

I then hot glued the tube portion to the flat mounting bracket portion.  After waiting about 15 minutes to ensure the hot glue was fully cured, I mounted the entire assembly to the aft face of the fuel injection servo.

A couple more shots of the taped up and hot glued air induction tube mounted to the fuel injection servo.

An alignment shot from the aft side… note the SCEET tubing is off to the right a bit.

A quick shot of the RAM air can SCEET tubing attachment bracket.  The wood block is to keep the adapter bracket pressed up tight against the RAM air can since I’ll need CS screws coming through the RAM air can flange going aft to secure the adapter.

Here we have both ends of the engine area induction system: the RAM air can and the future carbon fiber 180º tube assembly on the fuel injection servo.

A reminder of the modeled version of the air induction tube, for discussion below:

And one more side shot of the 3D printed mocked up air induction system tube.

Note how the lower forward-traveling tube below ends close to even with the start of the tube above it.  This is how I needed to 3D print the major curve of the tube, but ending it short also allowed me to design a curve and flared transition to mount the segment of 2.5″ diameter 6061 tube to the front portion of this tube assembly… obviously for mounting the interconnecting SCEET tubing.

The first order of business was to re-mount the bottom cowling and check the clearance between this air induction 180º tube version and bottom inside cowling….

I’m happy to report that I reclaimed my original clearance plus a good 1/8″ or so, with over 5/16″ total clearance between tube and cowling: 0.33″ to be exact.  Again, not the 1/2″ or so I would prefer, but beggars can’t be choosers and I’ll take what I can get.

With my clearance good to go, I needed to do two tasks that would take a bit of time to complete.

First, I filled the cracks on the 3D printed mockup of the air induction tube with raw epoxy, flox and micro.  I then put a weighted strap over the tube to compress it all a good bit while it cured under a couple of heat lamps (it was about 38º F outside).

I designed the flared 5º-curved forward segment of the air induction tube, that will intersect the 2.5″ 6061 tube adapter. I then kicked off the 3D printing of it before heading out for a quick dinner… with the 3D printer working this 3 hour print while I was out.

Upon returning home from dinner, I then sanded, acetone’d and marked up each end of the tubes in prep for joining them together with flox, and a few dabs of 5-min glue . . .

Which I did here.  After pressing the parts together by hand for a few minutes, and ensuring they were aligned correctly, I then clamped the assembly in place to let gravity do its job.

Here’s another shot of the flared (2.3″ aft intersection to 2.4+” forward <top> face) 5º tube extension flox attached to the front end of the 180º tube assembly.

Tomorrow will be a busy day socially, but I at least want to get the carbon fiber cut for the layup to get this 180º air induction tube assembly glassed/constructed.

I spent a good majority of the day 3D printing out the air induction tube, that actually ended printing early the next morning.  I spent nearly 5 hours on the first two 3D prints trying to print out both the Air Induction tube mounting bracket to the Fuel Injection Servo and the tube itself, which I had as the thin-walled tube that it would be in physical actuality.

However, the tube walls were too thin and my attempts at 3D printing it were proving problematic.  I then decided to print a more solid version of the tube, which worked… and which took over 12 hours to print.

From the first two failed 3D prints I did get a couple of good mounting brackets mockups for the air induction tube.  The bolt holes are aligned correctly and both the internal and external edge dimensions are good as well.

Tomorrow I intend to check this latest version of the air induction tube to check its clearance with the inside bottom surface of the lower cowling.  I’ll adjust fire from there in my effort to get the air induction system plumbing installed.

Since I returned from my vacation I’ve been working another round of all the small parts and hardware I’ll need to get all the myriad of components attached to the engine: Adel clamps, hi-temp Adel clamps, hose fittings, hose clamps, bolts with drilled heads, etc.

I dropped ACS and McMaster-Carr orders just before heading out on vacation, all of which were waiting for me on my front porch when I returned Saturday.  Sunday I pulled the trigger on a piece of the plans called out 0.02 inch 301 stainless steel for the canopy safety catch SC-1 (I have a 304 SS piece on there but it’s too weak and flimsy for the job).  I’ve also been working fitting assemblies to allow me to final pressure test all my engine fuel, oil and sensor hoses.

My next task on the list is to create the carbon fiber 180º air duct that mounts to the aft face of the aft-facing FI servo, loop around forward, then connect to the SCEET tubing attached to the bracket that I just machined.  I’ve spent the last couple of days doing more research and some cross-checks required before I go hot with making the air induction tube, and am hoping to start construction in the next day or two.

My research has included multiple hours of Fusion 360 instructional videos since I clearly need some “Continuing Education” credits (or remedial training?!) to brush back up on modeling parts in Fusion 360 CAD.

Well, I’d say the extra training paid off. It increased my CAD kung-fu at least to a point that allowed me to much more efficiently and gracefully create a CAD model of my Fuel Injection Servo air intake duct.  After fumbling around with it in the manual cardboard mockup arts ‘n crafts style, which is often fine, I simply needed a way to allow me to tweak the configuration and then fine-tune it.

That led to this:

As per the rendered model, this part will in fact be carbon fiber.  Much like the Fuel Injection Flow Divider (aka “spider”) bracket that I produced 5 versions of, this assembly will also get 3D printed until I get the version that fits optimally with decent clearance with the bottom cowling. I then plan on using the final model version as the mold to create the FI servo air duct.

It’s quite late here, and it’s been a long day of learning and then implementing my knew-found CAD knowledge to allow me to model up this part.  Tomorrow I’ll begin 3D printing it and press forward from there.

I’m going to run through these pictures below regarding the machining of the RAM air can SCEET tubing adapter bracket —that I finished machining today— quickly since there is a video covering all of it below.

I completed Phase 1 of the machining yesterday, albeit not without slight incident.  Phase 1 was the facing of the forward face that interfaces with RAM air can plate.  I also machined (or drilled via the mill) 4 holes to mount the bracket assembly to a plywood base to allow me to finish the rest of the machining process on the side opposite of Phase 1.

Here we have the bracket assembly at the end Phase 2, which is the external side of the tubular SCEET tubing adapter and the mounting flange of the entire bracket.

Here’s a closer look… note a 0.264″ diameter hole in each corner.

Also note the mess that milling away that much aluminum makes… honestly, it seems like kind of a waste.  But parts are needed!

Here’s another giant pile of aluminum chips.

I then bolted down the front corners and screwed down the aft corners to the plywood milling base.

I then removed all the hardware from the middle and commenced Phase 3, which was to create the hole in the middle and walled tube adapter.

I then checked to see if it would actually work, and Voila! It did.  The SCEET tubing fits snugly enough on its own to the bracket that I don’t need to hold it in place.

I then I temp mounted it onto the RAM air can just to get a quick idea of the clearance.  Note that after everything is installed, and the engine quick oil drain torqued to specs, I’ll most like trim it at an angle to allow clearance of the SCEET tube but also to still be able to slip on a plastic tube for draining oil during oil changes.

Ahh, and here we have the much awaited, critically acclaimed (not really) video… enjoy!

The very last thing I did before heading out the shop door for the evening was mount the fuel injection flow divider onto the new, rounded-corner Version 5 bracket and mount it in place on the underside of the engine.

This is the final bracket version I plan on doing, and I will use these 3D mockup to confirm the stainless steel fuel injection line lengths required for mounting the fuel spider on the underside of the engine.  These lengths will be annotated for future use, and to be clear: barring any significant apparent operating deficiency, I do intend on flying this bird for at least a year with the fuel spider on the top side of the engine.

Why? Because I truly want to know for myself the operating differences between having this fuel spider on top vs the bottom of the engine.  Call me a myth buster or a fool, no worries. But I do want to know.

Tomorrow I’m heading off on a cruise to the Bahamas with my girl for almost a week-long trip (her Christmas present to me).  So Bon Voyage and see ya’ll when I return!