Baffles #6

Time: 10 Hours

Now that I have all the fitting done with the forward ramps I could rivet most of the parts except the areas that tie the ramps to the side baffles. I was able to get most of the rivets with the pneumatic squeezer but had to get the rivet gun and bucking bar out to finish the rest.

The next task was to create the tie rods that close up the bottom of the cylinder baffles. These rods are made out of a stainless steel rod and have to be bent/threaded. The plans give you an initial bend angle to start. I measured and cut the length to start for the inboard ones. I made the bends and tweeted them to get spacing I needed. The idea is the bends will give the rod clearance over the other parts that lie at the bottom of the cylinders.

Once I was happy with the bends I grabbed my tap set and threaded the ends for a nut and washer.

I moved on to the outboard rods which are a little longer and need a second bend as these need to clear one of the oil return lines.

This what they look like installed. You can see that the rods pull the curved sections together and making a seal around the cylinder fins.

Before moving on to more baffle work I wanted to put on a layer of epoxy/filler on the snorkel so I can start the work of smoothing the surface. I also set a mixture of epoxy/filler/flox under the alternate air door so it sits flush.

Now back to the baffles and the start of the big top cuts. The idea is that you need to cut the tops of the baffles al the way around so that there is a gap between 3/8″ and 1/2″. This is easier said than done but just takes time. I realized that the support bracket in the left aft baffle was way to high based on how I installed it. So I removed the rivets and will make a new one later once I get the tops cut. With that part removed I put the top cowl on to see the areas that were touching on the aft and aft side baffles. I started with making small 1/4″ cuts off the top until I could get the cowl on with around an inch gap in the back.

Looking in through the gap on the aft edge looking forward you can see how the baffles look as they touch the inside of the cowl.

Now I had a manageable shape and had some areas touching and others not. To get an accurate scribe of the inside surface of the cowl you can use the “paper clip” method. The idea is that you install the clips along the edge of the baffle. Then install the upper cowl and as you press down on the cowl it pushes the clips down. Then you can measure down from the top of the clips, in my case I started with a 1/4″ measurement, and make a mark. You then connect all the marks to give you a line that matches the underside of the cowl.

I did this around five times slowly removing material. The hard part is after I measure I have to remove each of the baffles so that I can remove the material then put them back in place which takes a lot of time and effort. As the cowl “drops” on the aft end the shape changes slightly so I made smaller cuts to account for this. Here is a line of clips from left to right and how they ended after the cowl was put on. You can see a lot of them are pushed flush and a few have a little space left on them.

With the last cut I have a pretty even gap around 1/8″ all the way around the aft and aft side baffles with the upper cowl in its final place and the SkyBolts secured. So I will do the paper clips one more time and measure down 3/8″ to get the final gap. Before I could do the last cut I needed to figure out what I was going to do for the left side bracing. This creates a straight line across for the baffle seal fabric where the oil cooler bumps out. I had revealed that I riveted it on way too early and it was positioned too high. I decided to fabricate my own and make it fit as I needed it. I wanted to make sure I planned for the heater scat tube as this was the area I would install it since my oil cooler is now on the right side. So I started off with some card stock paper and made a template. After a couple of tweaks and measurements I transferred it to some sheet stock to start the fabrication process. I needed to have several bends as this area needs to be sealed up to keep the positive pressure in the engine area. Once I had the shape built I laid out rivet holes and match drilled it to the baffles. The lower flange was laid out with the scat tube pick up as a drill guide.

I was very happy with how it turned out and it should serve its purpose. With that part made I could use the paper clips across the entire aft baffle to make the final cut. I marked the outline of the scat tube pickup and drilled to make the opening.

In the last photo you can see the upper left corner of the brace I fabricated I now have a notch. That’s because I really carefully laid out the five rivet holes in it prior to getting the final cut done on the top of all the aft baffles. That ended up putting the upper most rivet hole way to close to the edge…dummy! So I just clipped it out and that’s that! It will be covered up by the fabric seal anyways but it’s that kinda of thing that is tough when fabricating parts is the forward thinking and the way forward thinking. From here I moved onto to forward side baffles. The process is the same, measure, mark, trim and repeat. I ended up with a nice 3/8″ gap all the way around.

Next up will be the forward baffles and there complex cuts.

Baffles #4

Time: 5 Hours

The last section is the forward baffles which are comprised of two pieces, the and right. These go right behind the propellor area and seal the area where the crank shaft comes through the cowl. I first clamped them together in place to see how much trimming would be needed. They also have two angles in them that try to match the ramps.

I worked the right side first and trimmed a little at time on the bottom until I had a perfect fit on the bottom and the curved portion of the engine case. Then I started on the left side. It’s hard to see in the above photo but the fit around the engine case is really bad, almost 3/4″ in spots. After looking this over Glenn suggested that I redrill the hole Vans punched for the bolt in the center top over to slide the baffle over and closer to the engine case. This would mean that I would have to tweak the angles of the side a little bit not much. So I did some measuring and came up with a good spot to drill the new hole making sure I would have edge distance for the new hole when I cut the new inboard edge.

Once I had the hole drilled I had to trim the bottom like the other side as well as the lower part of the center where the two halves come together.

This worked great and the gap is much better and will be sealed up with RTV later. So I started working on the bends of the sides to make them fit well. These eventually get tabs made out of angle that will tie the sides to the ramps. I made the clips and match drilled them to the sides and ramps.

On the left side I had to trim the tab a little to get it to sit good with the filter cover I made.

Now that the forward baffles were fit I moved to the right side conical gusset. This is a curved sheet in that ties the ramp to the lower cowl shape. It starts like a cone, small at the top of the ramp and gets wider at the bottom. This was a fun piece to make and took a while to get perfect. I started with a card stock template and transferred it to the sheet of aluminum.

After cutting it out I used the hand seamer and my rivet gun to shape the sheet into the shape I needed.

The shape needed tweaking a little but ended up perfect. I clamped it in place and match drilled the holes I laid out.

The left side can’t have one as the filter is in the way.

Next up will be to rivet some of these parts together, some will wait until final assembly. Then I will work on the bottom ties of the baffles. All this work leading up to the tough job of trimming the tops of the baffles to match the upper cowl.

ShowPlanes Oil Cooler Mount

Time: 2 Hours

Another modification I’m doing to my RV is to move the oil filter from the stock left side of the rear baffles to the right side on the engine mount. This allows for a much larger cooler to help with cooling my larger HP engine. To get the air from the engine area to the cooler is via a hole cut into the right side aft baffle and a fiberglass plenum. The cooler gets mounted to the engine mount via a two piece bracket and locks the cooler into a specific spot based on the geometry of the engine mount. I had the cooler temporary mounted to the brackets and used it with the plenum to get the initial cut line after I trimmed the side of the plenum to fit the cooler.

I returned the rear baffle and worked the plenum until I had a rough 1/4″ gap, this will get sealed with a rubber gasket eventually. To cut the aft side of the baffle ShowPlanes gives you a doubler with the hole steady cut into it. Unfortunately the hole in their doubler was too high for my plenum, not sure why but not a big deal…I’ll just make a new one.

The fit was perfect so I laid out a rivet line at the top, left and bottom. The right side could be match drilled to the baffle rivets.

After I had all the holes drilled and deburred I removed the material from the baffle.

After I was happy with all the edges on the inside I trimmed the top, bottom and right sides to make a nice fit. I dimpled all the common holes between the doubler and baffle. I also primed the surface of the double and riveted the holes except the row that are common to the side baffle as those will get done later.

This was one of those items that works in conjunction with the baffles that needed to get done while working on them.

Baffles #3

Time: 10 Hours

I repeated the process of bending the left inlet ramp just like the right side to get the forward edge to sit nicely under the cowl lip. Once that was done I trimmed the outboard edge of the ramp to allow the side baffle to bend in as well. Once I was satisfied with the fit I bent the lower portion of the side baffle just like the right side baffle. No pictures of any of these steps as they look just like the right side. One thing I did different than the right side is I didn’t trim or did as little as possible the forward length of the side or ramp baffles. I read ahead on others build sites to realize that you can cut yourself short if you are using a horizontal induction system, which I am. Using the horizontal versus vertical means that I will have no “scoop” on the bottom of my cowl, instead my fuel injection system will get its air from a filter and fiberglass tube, called the snorkel, mounted on the left inlet ramp. So this was my next task to get this monster to fit properly and build out the filter bracket. First up was to create a temporary attachment to the fuel servo. Eventually the snorkel will get help in place with four bolts but for now you don’t know it’s exact position in order to drill those holes. I wanted to be able to rotate the snorkel about its center on the servo. So I cut a piece of scrape sheet and drilled out four matching holes for the servo. From those holes I measured diagonally across all four to come up with the very center of that sheet. I also created a 3/4″ thick wood circle exactly 2 3/8″ across, the same as the opening on the servo side of the snorkel. I drilled a hole in the center of the sheet for a small wood screw that would hole the wood in place dead center. I trimmed the sheet to be more square and fit the area a little better as well.

Now I could bolt the plate/wood to the servo and have a pivot point for the snorkel to rotate about and keep it centered on the servo.

Not thinking about thickness of the bolt heads I dint like how far away from the servo they kept the snorkel flange. So I replaced them with several small zip ties which reduced the gap.

Ok so now I rotated the snorkel around to try its position and see where I would have any clearance issues. The only spot was right at an accessory lug on the SkyTec started. I did a little research on line before this and read about this issue. SkyTec allows for these lugs to be removed if not needed in there paperwork as long as you leave an 1/8″. So I could remove the unwanted lug or redo some fiberglass…our came The hacksaw! With that removed I rotated the snorkel up until it hit the underside of the left ramp. From there I outlined with a sharpie the shape of the top of the snorkel.

Using my drill, jigsaw, file and sandpaper I was able to remove this material to get the initial rough opening. I put everything back in place to see how it looked as I rotated the snorkel into place.

The fit in location was perfect, this hole will end up getting opened up to allow for a 3/8″ gap around the snorkel for the air filter. The snorkel will also get cut to give it a 3/8″ gap under the ramp. For now this position will allow me to drill for the four bolts that will hold the snorkel in place on the servo. So using a flashlight and a careful drill bit I drilled the center of the four holes enlarging them enough to allow for the 1/4″ bolts.

So now I could start to careful trimming of the top of the snorkel to give me that gap I needed.

To hold the air filter in place vans gives you bracket material that has a 3/8″ ledge for the filter to sit into. These brackets sit inside the snorkel and under the ramp. The plans for these are hand drawn and very confusing. I started with the aft section and trimmed the bracket to fit inside the snorkel and up under the aft section of the ramp. Once in place with some clamps I match drilled the holes for now. These will get screws eventually so the snorkel can be removed. I also drilled five holes through the bracket and the fiberglass of the snorkel. These holes will be used to rivet the bracket in place.

From there I moved to the two side brackets starting with the outboard one. I drilled for the five holes in the fiberglass to see how much material I would be working with for the screw holes up into the ramp, this is where I had to grime material to get the side baffle close to the cowl lip. I had enough space for regular #8 screw nutplates but not for countersunk #8 nutplates. That just means that these three screws will not be countersunk on the top, not a big deal at all.

The inboard bracket I’m going to wait to drill the screw holes until I have the baffles behind the ring gear done as they have a couple pieces of angle support that could be in the way. That way I can work through those issues at the same time as I install those baffles. I did drill the five holes into the fiberglass for that inboard bracket to hold it in place.

I removed all the parts so I could open up the hole to allow the filter to drop in and sit on the ledge of the brackets I installed. Again I used various tools, the band saw and sand paper to get the opening just right. The small amount that would remain on the forward edge of the ramp wouldn’t be of any use so I decided to cut it out. This area will be covered with the baffle seal material when it’s all done.

The bent edge of the side baffle is too long so I needed to trim it as well.

After the areas were fine tuned I installed the snorkel to see how it fit with the new opening. I was very happy with the fit and how it turned out.

The two aft corners will get sealed up to prevent air leaking. I grabbed the filter to see how it fit in place.

There are all kinds of ways to secure the filter so it doesn’t move, Vans gives you two small parts to hold the left and right side but I didn’t like how they fit or looked. So I decided that I would create a solid piece of .032″ sheet that would frame the top of the filter. It would be held down with six screws, two on each side. I also will put a 90° bend down on the forward edge to keep the filter from moving forward. I started with the solid sheet and aligned all the edges to get a perfect fit. I installed the lower cowl to see how it fit in place as well.

Once I had the overall fit perfect I measured for the center cut out and marked it to cut.

After I rough cut the hole with my Dremel cut off wheel I used a file to straighten all the edges. I used sandpaper to clean all edges up and smooth out the file marks. I used my break to bend down the forward edge after making a couple cuts to create a “tab” on the forward edge.

This makes for easy access to the filter when it needs cleaning or replacement.