Well, yet another day and more goals NOT reached!

I had planned on getting the cylinder #2 standoff supports machined/cut out and glued on today, but too many holiday social planning and prep events filled my day.

I was able to remove the tape, weight and wedges off of the left top outboard inter-cylinder baffle, which is the completion of all the major inner CF baffle pieces on the left side of the engine.  I do still have an inter-cylinder piece (plus bracket) that needs to go in between the base baffles to fill that void (right around the orange fuel line).

Again, the weather has been pretty darn cold here as well, so that isn’t helping things.  I will try to get out to the shop tomorrow and get the cylinder #2 standoff supports made and glued in place…. but the way things have been playing out this holiday season, I ain’t promising anything!

Inching forward…

I’ve been doing a bunch of holiday prep since I’ll be heading out of town to spend Christmas with my daughter, son-in-law and grandkids.

My goal for the build today was to get the left side top outboard inter-cylinder baffle glued into place —including the crazy machinations in securing it in place during its cure!— and then move onto machining the right side cylinder #2 aft standoff supports and get those glued into place to allow me to then get the actual aft baffle attached tomorrow (after the 18 hour cure cycle).

Well, I did get the left side top outboard inter-cylinder baffle glued and secured into place.

Then, before I jumped into machining the cylinder #2 standoff supports, I cleaned up all the inner baffle forms, carefully packed them back up in the box they were sent to me in, and then ran downtown to send them back.  Clearly the chapter of this build involving these CF inner baffles is ever so slowly coming to a close.

Even a bit slower after the events that ensued upon my return to the shop.

I worked out the CAM post processing for the cylinder #2 aft standoff supports and prepped some 0.090″ 6061 to machine for the creation of the standoffs.  Not having used the milling machine in a few months, it required a good 45 minutes of TLC in cleaning and oiling before I got started.  I also forgot a couple of weeks ago I had a pressure line inside my compressor closet burst, which needs to be repaired… so I had rig up another compressor to handle those duties (my milling machine quick tool changer, chip removal mister and air blaster are all on one of these lines).

Once ready to go, I learned that my handy hack of using super glue and blue tape has its limits: a thicker material such as 0.090″ with a smaller footprint just can’t hold up against the pressure of the end mill biting into the corner as it cuts… I tried this method twice with no joy.

At this point in the evening is was late and after multiple iterations and all the required prep, I figured I will have to do some more Neanderthal machining by cutting these things out with my Dremel Tool.   Jess was due over in about an hour to make us a nice dinner, so I decided to kick this can down the road until tomorrow since I would most likely only get one of the two standoff supports manually cut out and shaped (I still have a thought on machining standoff #2 which I’ll attempt tomorrow).  Only gluing one of the two standoff supports into place clearly wouldn’t put me any more ahead with the cure cycles required.  So I called it a night…

I had yet another very busy day in prep for my upcoming holiday adventures, again getting nearly nothing done in the shop.

I did carefully remove all the wood supports and straps that secured cylinder #1 and #4 baffles in place during glue cure.

First off though, here is a pic of the elusive frontside baffle on cylinder #3.  I finally remembered to grab a shot!

And here we have the baffle now secured to the aft side of cylinder #1.

Finally, here is the baffle for the front side of the cylinder #4.

That’s all I have to report for today.  I do plan on machining the standoff supports for the aft-side baffle on cylinder #2 ASAP to get that mounted.  Then it will back to the top center area on each side of the engine to get the inter-cylinder baffle pieces installed.

I’ve been a bit busy prepping for Christmas and New Years as I’m heading out of town to my daughter’s for Christmas and then on to Nashville and the mountains of Tennessee to ring in the New Year with Jess.

Yes, between my non-build shenanigans and the cure time for the Toyota FPIG glue on the baffles, it’s taking a number of iterations to get these baffles on.  The current cold weather doesn’t help and the crazy machinations required to pin each individual baffle to its respective cylinder for cure is also somewhat of a gargantuan feat each round.

Case in point: Note the insane amount of dunnage required to both the secure the aft left baffle to cylinder #1 while at the same time ensuring that nothing on the engine gets damaged either.

Here’s a low-angle shot of the baffle (that is pretty much hidden from view from all the wood blocking) going onto the aft side of cylinder #1.

In the same manner, here is the baffle for the front side of cylinder #4 glued and secured in place.

And this is how that looks from the aft side of the engine.

I just simply didn’t have time to machine the cylinder #2 standoff supports yet, but will get to it my next major outing in the shop.  As par usual, after I grabbed these shots I set up a heat lamp under each side of the engine pointing up and then covered the top of the engine to keep the heat in during the baffle glue cure.

In addition, I did actually get the baffle installed on the front side of cylinder #3 last night.  I thought I had a pic of that but didn’t and consequently completely forgot about it in yesterday’s blog writeup.  I’ll get a pic of it for tomorrow’s post.

Pressing forward… slowly!

Today I got all the remaining outside cylinder (fore & aft) base baffles glued onto the engine cylinders.  I thought I would show one of the baffles here with the Toyota glue applied just before it went onto the cylinder.

Here we have the 4 final cylinder base baffles glued and secured in place, starting clockwise from top left: Aft left/cylinder #1, aft right/cylinder #2, front left/cylinder #3, and front right/cylinder #4.

You can see I employed everything but the kitchen sink to secure these base baffles in place during cure, each cylinder/baffle combo clearly being completely unique as compared to the other ones.  It took about 45 minutes per baffle to prep, create and dry run the securing accoutrements.

In addition, the Toyota glue needs 15-18 hours to set up for final cure, so I left them to cure and pressed on with some Neanderthal machining.

I made up templates (one shown below) for the different sized inboard and outboard fin dip filler tabs since the inboard is a bit bigger than the outboard.  I tried to put these into F360 CAD but it was being finicky (or I was) so I punted and just went ol’ skool using the bandsaw and the Dremel with a cutoff wheel to get them cut out.

I didn’t grab a shot of the 4 outboard fin dip filler tabs before I glued them into place on the respective cylinders, the left shown here.

I used 0.050″ thick aluminum on the outboard because the fin at this point is the same thickness as all the other fins, around 0.080″.  The final inboard fin on the cylinder head is the thickest of all the fins, nearly 1/8″ thick.  Because I had some scrap that fit the bill in not having to cut into any fresh stock, I used 0.090″ thick aluminum on these inboard fin dip filler tabs.  Here they’re shown with the template I made up.  The marks are again from my Neanderthal machining where I had to use vice grips to hold the tabs while shaping them… these inboard tabs especially are not cosmetic, so I’m not overly concerned about these “tooling marks.”

On a few fins, both inboard and outboard, I had to account for paint buildup globs and actually create a divot in the mating edge of the filler tab to allow it to fit flush with remaining dip surface edge.

Here we have both inboard and outboard fin dip filler tabs glued in place (Toyota FPIG) on the left cylinders (pic 1) and on the right cylinders (pic 2).

This shot shows the thicknesses of the inboard vs outboard fin dip filler tabs.

Finally, I’ll remind everyone that these filler tabs are my blatant copying of Dave Adams’ same efforts that he wrote-up in a COBA Canard Aviation article.

Tonight was again a very cold night, with frost already forming late in the evening.  I put heat lamps under the engine pointing upwards and covered the top of the engine just to ensure there was decent temps for the glue to cure.  Tomorrow I plan on installing more baffle segments while also machining the 2 each cylinder #2 fin/baffle standoff supports.  At this pace it will be at least another 2 days before all the inner baffles are installed.

I had to do a bunch of running around today so didn’t get into the shop until mid-evening.  My goal was to get at least 4 baffle segments installed and I’m happy to report I accomplished that… in my effort of doing so it felt the same to me as a video I saw where a kid juggled Rubik’s cubes while solving them.

First, I removed all the aluminum outer front and side baffle walls to ensure I could get the placement down on the front cylinders’ base baffles.

To get the 3x glue swaths in the correct spots and then get these internal baffles set into place was definitely quite the puzzle, unique on each one.  On the aft side of the forward cylinder I actually applied the glue to the cylinder fins and only actually applied the glue to the baffle at the center.  That baffle went on first.

On the forward side of the aft cylinder I applied the glue to the center and top, then slowly and careful wove the baffle in under the push-rod tubes before setting the top and middle in place.  Both Mike Beasley and Steve Beert said they used wood wedges and tape to wrangle the baffles and keep them in place during cure.  Me being me, I went a slightly different route and found that the dense foam that comes in shipping boxes worked a treat for securing the baffles in place.

Once I got the aft inside baffle top and center secured in place, I got underneath the engine and used a pick to pull down the bottom edge of the baffle just enough to use a stir stick to apply the bottom swath of glue.  After the bottom swath of glue was applied, by pushing the center larger piece of foam all the way down in between the cylinders, it served to press the bottom aft baffle edge up against the cylinder for cure.

On the underside, for the forward baffle on the aft side of the front cylinder, I employed the cylinder oil return lines to secure wood blocks and some foam strips to add just enough pressure to keep the baffle in place.  Note the installed outboard inter-cylinder baffle that I glued in place last night.

I then did the same thing on the right side.

Now, let’s discuss baffle angles and airflow through these base baffles.  As you may have noted the forward and aft base baffle sets do NOT have the same air entry and exit angles: for a couple of different reasons (Also, let me point out here that I am focusing on FUNCTION over FORM and am looking to optimize airflow for cooling… not the goal of having standardized looking baffles).

First, the air coming off the ramps are significantly different in the angle at which they come into the cowling via the armpit air scoop.  The air hitting the inlet ramps for the front cylinders turn almost directly upwards —or at least at a much sharper angle— as compared to the more shallow angle the air on the aft ramps is directed.  This obviously means direct air flow needs to be more vertical, or slightly angled aft, on the front cylinders vs the aft cylinders (clearly there is a HUGE pressure component to how our engines are cooled, but I’m not getting into that here).

Next is a matter of simple space… or more specifically clearance.  Even if my goal was to make the front and aft base baffle entry and exit points the same, the oil return lines under the cylinders would require major trimming of the bottom flange on the forward baffle.  There’s just very little space on the bottom side of the forward cylinders.  That being said, I will need to create a half-moon notch on the bottom tab of the aft right side base baffle (not installed at this time) to account for the cylinder #2 oil return line.

Here’s an underside shot of the right inter-cylinder base baffles glued and secured in place.  Again, note the tape and wood shims removed from the bottom outboard inter-cylinder baffle (I discussed in yesterday’s post how the form for these outboard baffles is not perfectly true, which makes them set a little wonky when in place).

The pictures don’t do the amount of effort in planning, dry runs and execution justice to get these 4 inter-cylinder base baffles glued in place.  All in all I spent nearly 4 hours on getting these baffles alone glued into place and secured for cure.  Tomorrow I plan on knocking out another good chunk of the inner CF baffle installs as well.

Today was all about finishing the trimming, shaping and creation of the top outboard inter-cylinder baffles that I micro’d together last night.

I did a good bit of research today to ensure I knew what the heck I was doing because I wasn’t completely understanding the configuration of these specific baffles, even though Steve Beert sent me another conformational pic.  What was confusing me was why was there no baffle coverage on the fins in between the 2 cylinders?

I went back to Andreas Christou’s document, Design for optimal cooling efficiency, and therein lied the answer!  Things are a bit different from our smaller cousin, the O-235, than they are for O-320/360s… read on:

“The Lycoming O-235-L2C Cylinder head… has less fin depth at the sides, and some attempt has been made to increase cooling on the exhaust valve side of the cylinder. The fin depth next to the exhaust valve is slightly more than on the intake valve side. There is enough fin depth to justify using Bid/RTV baffle material between the cylinders so that the flow of cooling air is divided into two sets of fin tubes. This will distribute more cooling air to the exhaust valve side and will also keep hotter air from the exhaust side from heating up the intake side and consequently raising the temperature of the incoming fuel air charge.”

[Note the red line in between the cylinders denoting a baffle]

Andreas then went on to state this about the O-320/360 motors:

“Placing Bid/RTV baffle material between the fins of the cylinder heads would do more harm than good. Any inter-cylinder baffle material would block the flow of air past the intake side of the cylinder.”

[Note there is NO red line in between the cylinders denoting a baffle]

Eureka!

This would also explain why my buddy Marco found issues on his O-320 Long-EZ because when Terry Lamp built it everyone else was installing O-235s.  The baffling in that Long-EZ’s O-320 was per the O-235 IIL plans and caused some significant heat issues. I’m not calling Terry out nor being critical of him… that is an outstanding bird, and the poor guy had only the guidance for the O-235 to follow at the time!

With the above foundational info in hand, I then got to work on what Steve Beert calls the “Starship Enterprise” baffles.  First, here’s a shot of the separate baffle segments micro’d together to make one baffle piece per side.

I then marked the bottom edge of the top inter-cylinder baffles for trimming…

And then trimmed them up.

After another round of confirming the shape and configuration of these baffles, I then trimmed them up even more to their final shape on the lower side.  Here’s Side A:

And here’s side B.  I also final trimmed the top sides as well including the curly Q’s.

I had thought about and even mentioned spray painting the micro black with hi-temp spray paint, but then just decided to use the Toyota glue to add just a hair more depth, fill some gaps around the edges and of course cover up the white micro.  In addition, this allowed me to use the Toyota glue (RTV? Whatever it is!) and get a feel for how it could be applied and manipulated.  It’s not the sexiest looking stuff here, but it’s done, and remember: these are on an engine!

With my mastery of the Toyota glue complete (haha!) I decided to knock out some low hanging fruit: attaching the bottom outboard inter-cylinder baffles.  I figured these are pretty low-vis baffles and if I really got messy with the glue while slapping these things into place then they wouldn’t be very noticeable, eh?

I started on the left side and applied the Toyota glue in 2 strips across each face of the somewhat Λ shaped baffle and then taped it in place.  I will note that when I cut the baffle on the imprinted edge that the form created, it came out about 0.030″ narrow on each side.  Each edge is still on the respective outside fin, just not fully all the way around… it’s just a tiny hair off kilter so each side was a task of getting the best coverage possible with a slightly askew and every-so slightly narrow baffle.

On the right side the tape wasn’t holding at all… and it was quite the melee getting it on and set in place.  As you can see I used wood and cardboard to wedge it into place.  Here’s a shot from the inboard looking out…

And a shot from outboard looking in.  I can definitely say I’m glad that this small but crazy baffle is in place!

In other news: I forgot about these 3D printed standoff supports which I actually printed out yesterday and just got around to taping them in place on the aft side of cylinder #2.

I then test fit the cylinder #2 aft baffle in place.  Both standoff supports need some very minor tweaking, with the inboard standoff (shown) needing a bit more added to the depth while the outboard standoff needs just the opposite.

And with that I double checked the bottom outboard inter-cylinder baffles and called it a night.

I started out today by focusing on trimming up the remaining engine inner baffles that I had not gotten to yet, which were primarily the top outboard inter-cylinder baffles.  Knowing that Steve Beert is The Godfather of CF inner baffles I sent him a quick message asking him a few questions specifically regarding these inter-cylinder baffles… in fact, I sent him this pic below to clarify exactly which ones we were discussing.  We had quite an exchange over text on installing the baffles.

Then a bit later Steve called me with yet even more information, tips and builder tricks on these inner baffles.  We spoke for a good 45 minutes, where he also went over some of the background of the design (Terry Crouch having done the airflow math and primary design with a lot of input by Gary Hertzler) of this style of inner cylinder CF baffles.  I sent this pic below as well of the bottom-side outboard inter-cylinder baffle with a question to clarify some info Steve have presented to me.

After talking to Steve, with now a bunch of informational arrows in my quiver, it was time to get to work.  I finished trimming and cleaning up the top outboard inter-cylinder baffles, or the baffles that Steve nicknamed: “The Starship Enterprise” and set them into place between the cylinders each side.  Note the taped popsicle sticks on each end to keep the separate baffle segments both in the proper left-right position on their respective cylinders, and also pressed firmly against each cylinder… the intent here is not to create a gap between the baffle segments, but to account for these two previous mentioned factors.

I then followed Steve’s construction sequence by whipping up some micro with the high temp HTR-212 epoxy.   This was a bit tricky both in access to the gap (on a step ladder leaning over the top of the engine) but since I didn’t want to make a mess on the lower internal fins of each cylinder (or the floor, etc.), I had to ensure that the micro wasn’t too runny… thus the medium thickness micro —with emphasis on the thicker— was a bit trickier to stuff down in that narrow gap without it wanting to come back out with whatever implement was being used to get it in there (a variety of thicknesses of stir sticks).  Patience won over though and I finally got a good bead of micro in on each side.

I’ll note that Steve used West’s black dye in his micro in this application, but since I didn’t have any on hand I will simply paint the white micro with hi-temp black spray paint.

Although the weather isn’t as freezing cold this evening as it has been off and on lately, I set up a heat lamp under each side of the engine pointing upwards and covered the cylinder areas with some aluminum foil covered insulation pieces to keep the curing micro from getting too cool overnight.  And with that I called it a night and left these micro’d inter-cylinder baffles to cure overnight.

To start off with, I’ll note that I don’t like bashing smaller companies who are putting out products for the experimental aircraft world… it’s great to have choices.  But enough is enough.  GRT really gets a bad grade this round (D-) with my order on their compression style EGT probes.

As par usual, there were zero issues with the mechanical process of ordering these EGT probes.  Call them up to ensure they have in stock, order two of them, card info, confirm address… 5 minutes and done.  On my porch a few days later.  EZ-PZ.

GRT’s Achilles heel, and biggest negative, is their product information and documentation.  I had a conversation with Nick Ugolini on this a while back, and he told me as an engineering tech writer he offered to write their manuals for them… for free!  They refused.  I asked another buddy of mine who uses GRT if he would go that route again with any future aircraft… he said no.  Why?  Not because of the quality or the functionality of their products —which is excellent— but again, with no robust documentation you spend way too much time on the phone with them and/or hunting for information that should be right at your fingertips.

Case in point.  I called GRT to get info on their compression style EGT probes because, once again, there is literally ZERO information on these on their website.  I asked about any recommended processes I should know for mounting these into the exhaust pipes? How does the configuration work exactly?  Do they sell the threaded mounting bungs? (no);  Any preferred vendors or sources of supply for the threaded mounting bungs? (no); Now, admittedly this last one I’m fuzzy on, but I swore I confirmed that the required mounting bung threads were 1/8-NPT.  Apparently not.  Neither was that information provided (via product info sheet) nor offered when I was clearly asking every question I could think of regarding the install of these compression style EGT probes.

Well, when my 1/8-NPT threaded stainless steel mounting bungs arrived today from McMaster-Carr, I quickly noted that they were not the correct size.  But what was the correct size?  After 15 minutes of no joy in trying to figure out this odd thread size, I punted and called GRT, leaving my message to have them call me back later as the standard process goes.  And a half hour later got my answer: M8 with 1.0 pitch.  Yes, being in the good ‘ol US of A we tend to use ASI vs metric, but I do use metric hardware enough to know that the standard pitch for an M8 thread is 1.25, not 1.0.  Hmmm?

After a good 30 minutes of searching in vane on the Internet for a vendor that sells a stainless steel M8-1.0 threaded mounting bung, I gave up and finally went to the only source of supply I could think of that would have such an item: Ebay… well, China to be even more exact.  Yep, there they were!  Less than 20 bucks for 3 of them shipped from Shanghai and only a month to get here.  Thanks again GRT!

In other news . . .

Today I finally finished the trimming and shaping of the majority of inner CF baffles. Over the past few days I’ve done a few redo layups since using tape on the forms there were few quality issues I had with some of the baffles. Thus the redoes.

With the glossy surface the lights blanket out some of the CF print, so I grabbed these lower angle shots to show different perspectives on the CF.

And as a reminder, the aft inner baffles are the same print as prop spinner and flow guide.

Overall I’m very happy with how the CF inner baffles turned out, and plan to start mounting them to the engine… after I get the aluminum fin standoffs made up and mounted to the cylinders first.

I started off today by calling GRT to order 2 of their compression fitting style EGT probes.  Knowing what I know now and the much improved clearance that these will provide I figured the time is right to get them installed.  Plus I confirmed with James that he would be able to weld on the required 1/8-NPT threaded bungs onto the exhaust pipes.  I’ll simply hold the other ones as backups for my other 2 hose-clamp mounted probes.

Out in the shop I started off by pulling all the tape and plastic off the cylinder #2 aft baffle with the fin standoff support bump now integrated into it (pic 1).  I then trimmed the CF around the edges a bit, removed the protective tape off the cylinder, and set the aft baffle back in place for a test fit (pic 2).

Here we have a shot from the side to show the cylinder #2 aft baffle with the fin standoff support bump integrated into the baffle (note: the baffle is about 1/8″ low so it’s not fitted to the cylinder in this pic).

I’ll remind everyone that this fin standoff support bump in the baffle is to allow for these standoff supports as Dave Adams did on his #2 cylinder as well.

I took a couple hours to cut some more CF and lay up a few spares of the inner baffle segments in case I ever run into trouble or just need them in general… before I send the inner baffle molds back.

I’ll also note that the Toyota RTV —that is apparently the cat’s meow for mounting these CF inner baffles— was delivered today.  Now I have no excuse not to get these baffles trimmed up and installed on the engine!

Which I plan on doing over the next few days.