In prep for installing the baffle material, I used my go-to method of using construction paper to make templates for each piece prior to cutting the actual material. I targeted 2.5″ above the metal baffle material based on what others have done. I did a few test fits with the upper cowling on to make sure that length seemed like it would work. I tied to make the pieces overlap around the split points in the metal in case I ever need to take the whole assembly apart at a later time.
I then marked the templates with a line along the metal baffles to mark their position for reinstallation later on. I also marked out a line with enough edge distance for drilling 1/8″ holes to pop rivet the baffling material to later.
Once that was done, I removed the templates and cut out the material one piece at a time. I tried to cut such that the natural curve from the material roll would be in the direction I wanted the material to lay.
The method I found worked the best to punch holes in the baffle material was to first tape the template on the piece.
I then used the previously drawn line to place the template/piece assembly in place relative to the metal baffle making sure I had enough material for the overlap spots to the adjacent piece. I would use a drill to cut away the construction paper enough to mark the spot of the hole to be punched. I did the first 2 holes, then punched holes.. put the piece back into place with clecos and then drilled the remainder of the holes so I didn’t have to try to hold the assembly in position for the entire sequence.
I then used a punch to make the hole in the proper spot in the silicone baffle material.
Below are some pics of the final install. I did have to take some of the curl out of these pieces as they tended to curl inwards a little too much. I rolled each piece by hand in the opposite direction and sat some weight on the pieces to take some of the curl out. I also used some duct tape to hold adjacent pieces somewhat together. This will simulate the eventual RTV that will be used to hold everything together.
I then did something similar to the plans for the stock cowl to bridge the gap between the air intake tubes and the cowl. I used the metal strip material provided and curved it to match the round intake shape of the cowling. I then matched drilled 3 holes for #6 screws to hold this to the cowl. I cut some additional baffle material and used contact cement to adhere to the metal strips.
Below is a picture of the iniital test fit of this strip/baffle material fit. It seals up the small gap between the cowling and the intake tubes by resting on the inside of the air intake tube. I’ll likely trim this piece a little more for a better fit. Note also that I was sort of holding this in position to take a picture so the alignment is a little off, but you get the gist of what I am trying to accomplish here.
In order to get the top cowling back on, the baffle needed to be trimmed. I saw two ways to do this, and I ended up sort of using both. I started by elevating the top cowl 6″ above the lower cowl. Care was taken to make sure it was aligned both fore, aft, left, and right to the bottom cowl. I just used some pieces of scrap wood and clamps that I had lying around on each corner on the outside of the cowl. I measured in multiple locations along the horizontal split to be sure I was satisfied before moving on.
I then made a tool out of a tongue depressor and an aluminum block I had. I taped a sharpie to the bottom of the block and adjusted the stick to get exactly 6″ from pen to top of the stick. I didn’t take any pictures, but the idea here is that you have enough room (with the 6″ elevation) to get your hands/arms inside to hold the stick at a 90 degree angle with the sharpie along the inside of the baffle. Holding the stick on the inside of the upper cowl, you move it aft tracing the contour of the top cowl onto the baffle which will serve as a trim line.
I then trimmed to that line. That basically got me to flush. One could certainly add some extra to the length of the stick to get the the gap you’d like to achieve. Instead, once the initial trim was done, I utilized the 2nd method of paper clips all along the baffles. You barely stick them on and then place the top cowl into position. They slide downward and give you an exact indication of how much gap you have at that location to the top cowl.
Below you can see the results of the first attempt. You’re shooting for somewhere between 12/32″ and 16/32″ gap per the plans. At each paperclip location, I wrote the number of 32’nds needed to get to 12/32″ by measuring how high each paperclip was above the edge of the baffle.
Those measurements basically were used to draw a new trim line.
I ended up doing this for a couple of cycles until I was completely satisfied with the gap all the way around. Making smaller adjustments in specific areas as I went. Below isn’t the best picture, but it was the results of the baffle trimming with a gap to the top cowl.
I fabricated the clips and drilled them into position per the plans. I’m holding off riveting most of this stuff until later.
Now that the baffles were trimmed, I decided it was time to affix the top cowl inlet ramps. I placed them into position with clecos and some scrap metal strip to hold them in place at the front.
I then test fit the cowl and had to trim the outer side baffles more to account for the curvature. I did get somewhat lucky due to my cowl being so far forward based on my prop/spinner setup compared to most. The ramps didn’t require trimming at the prop governor to at least test fit. I did end up trimming around to give some more clearance, which I’ll foam in later to provide a good backing for baffle material.
Once I was happy with their location, I epoxied them into place. Later I will layup some cloth, but for now just epoxy to hold them in position. I also did a single layer of cloth and some peel ply on the inlet circle just to hold that area into position.
I then laid up 3-4 layers of cloth for the underside of the circular inlet.. Placed that into position and let it cure. I sanded down the outside area and added micro. Once that was cured, I sanded to a smooth finish.
With the upper ramps completed enough for now, I moved on to customizing the center baffles. I started with the right side, seeing it’s the easier side without compressor interference to deal with. I cut the stock baffle leaving just enough flange to rivet a new piece that would angle toward the inboard side of the inlet. I first made a template from construction paper and got it as close as I could. I transferred to metal and worked on trimming to get a good gap to the upper inlet ramps.
I then spent some iterations trimming this custom piece to match the curvature of the upper inlet ramp with some gap for baffle material. Below are the results.
To hold the inboard side in place I fabricated up some 3/4″ x 0.125″ Angle. Seeing there was a slight bend in the baffle I just created near the inlet, I marked a cut to match that bend in the angle. I marked and cut out a “V”
Below is the end result after match drilling and cleco’ing the baffle to the angle.
I utilized 3 screws to tie the aft piece of metal holding the carbon fiber ramp to the front pieces, including the piece of metal that runs under the carbon fiber ramp. I trimmed the excess away on the inboard side of any carbon fiber and metal plate so it didn’t protrude past the angle.
I then did a similar thing using a template on the left side. I decided to use one piece of metal to wrap around the governor and bend around the AC compressor belt to box it out of the inlet area.
Once I was satisfied with the paper template, I transferred it onto metal, cut it out, and made the needed bends as shown below.
I then worked to fabricate another short piece of angle with a notch cut out for AC belt clearance to hold the inboard side in place. I drilled 2 holes for #6 screws to attach to the stock baffle that I had cut off and left a bit of a flange for connecting my custom piece to.
Now that the basic shape of the left intake tube was formed, it was time to sand it down to perfect shape. I used mostly the Permagrit sanding blocks for this task, and it was relatively easy. Of course, at some points I had to put the lower cowl on to make sure I had clearance to it. I also carved out a bit more in the back for the AC hose connections to the compressor.
I then laid up 4 layers of cloth and put some peel ply over the top and let the tube cure overnight.
Of course prior to doing this I covered the foam in packing tape as a release agent and also sprayed some silicone based release agent on that for good measure.
Once cured, I removed all the foam inside of the tube and test fit it.
I then cut some cloth to close out the top part of the tube where I had cut for clearance to the compressor. 4 layers again were laid up and peel ply placed over the top.
Once cured I test fit the tube once again to make sure things looked good. below you can see the blue sharpie lines that I used to mark the cloth for cutting pieces to shape.
Then it was time to wrap a single piece of cloth to span the gap between the two tubes to join them back together. You can see the black line I marked for alignment. I also used a jack to allow the tube to sit on vs. having gravity pull down on the tube while this was curing. I used a single layer on the outside, because clearance to the cowl is a bit tight. Once this cured, I placed a thick layer of flox on the inside of the tube to fill the gap and create more strength in this area.
One of the other tasks that needed to be done was to redesign the air ramps seeing I’m using the Showplane’s cowling and the stock metal ramps were cut out for this intake system. I fabricated a .032″ thick piece wide enough to go under the baffle angle and still protrude enough to serve as a flange for the new ramp. This will be bent downward somewhat depending on the angle between this and the from of the intake. It’ll provide a nice flat surface for attaching the ramp material to with screws.
I also bent up some of the side baffle material to provide 1 screw location. I also decided to fabricate up a metal piece that sits up front on top of the intake area. It has a bent flange that will rivet to the side baffle material. I’ve left everything to the inside (closest to the flywheel) long for now. Once I get the center baffles completely figured out this area will be trimmed and I suspect some aluminum angle will be used with some screws to connect the front metal piece to the aft piece I made with screws.
I then cut some carbon fiber material I bought for the ramps to fit in the ramp area. Again, leaving the inboard side long for now.
I then match drilled everything, added nut plates, and screws to hold everything down.
I put the center baffle material in place after cutting it somewhat. This will need to be angled back towards the intake opening. In fact, I may cut the piece coming out towards the flywheel and rivet in a new piece of my own at an angle to achieve this.
I really had to trim away the left center baffle piece. It interferes with the AC compressor quite a bit. So I decided to cut the forward most section completely off, leaving enough material to rivet more metal to later, and also the notch for the aft part of the prop governor. Later, I’ll work on a custom piece to go over the prop governor and along the ramp to the intake area.
The same process was repeated for the left, with the exception that the compressor complicates the ramp..
I decided the best way was to use construction paper to create template prior to attempting to cut the carbon fiber piece.
Now that the main part of the cowl is fitted, it was time to move onto getting the baffling started.
The start of section FF2 of the plans.
You start off by marking up the #6 cylinder baffle for the scat tube that’ll go to the oil cooler. Also some holes for the top spark plug wires to pass through. Below you see the flange located in place and some holes drilled per plans.
The inner and outer circles were marked. The inner circle was cut out to allow air to flow through to the oil cooler.
The entire #6 assembly is then all riveted together.
A similar thing was done for the #5 baffle. The one thing I did different here was to utilize the RV-14 baffle modification. This provides more space between the aft-most cylinder fins and the baffling to get cooling air through and avoids doing “the washer trick” that several refer to.
It’s key to do this prior to cutting the 2” duct hole as it will need to move up.
I started by cutting off the existing piece of the baffle that wraps around the cylinder.
I then put the CB-00028, CB-00029, and CB-00030 pieces I ordered from Van’s in place of the wrap around piece that was cut off.
Below you can see that I relocated the 2” duct hole a little higher up on the baffle compared to the plans.
I worked on adding the doublers on the other baffle pieces only to end up with a pile of baffle parts ready to trim, as needed, to fit around my valve covers.
I worked on fitting the #5 and #6 cylinder baffles in place and putting on the Aerosport engine mount covers. 3 #6 screws were used with nut plates to attach making sure to not drill into the mounting ears.
Below the baffling is complete, yet to be trimmed.
In anticipation of starting on the Showplanes intake I temporarily installed the exhaust pipes.
I also worked on making sure my AC compressor was as close to final position as possible. It’s a bunch of tweaking with a couple of different belt lengths, mounting spacers, and arm lengths, to get it all right. There is very little space between the belt tensioner and the starter.