More Baffle Work

Time: 6 Hours

I spent some time in the hangar yesterday and today trying to finish up the baffles. I worked all the airseals around the front baffles and got them to sit almost perfectly. I had to trim the upper air ramps a little to make it happen. I’m pretty happy with they way they seal and fit but I’m hoping they lay down after they are used on the warm engine aa they make it a little difficult to put the top cowl on due to their stiffness. So the next baffle task was to drill for three cooling blast tubes. These tubes will direct air to areas that need cooling. That’s for me are the two P-mags and the alternator. So I laid out where I wanted them and drilled a pilot hole followed a 5/8″ hole using the step bit. I used adel clamps to secure the ends and direct them to the P-mags. I ran out of the tubing and had to order more from Vans. I did drill the hole in the right side forward baffle for the alternator blast tube. I put in a small piece of tube in to check the fit. Two more holes I need to drill for are for the spark plug wires. I’m using a special pass thru clamp from Aircraft Spruce that holds the wires firmly as they pass thru the baffles. The shape looks like a number eight. I was almost sure I was finished with drilling on the baffles when I realized I had forgot the blast tube for the engine driven fuel pump. I had bought and installed the ShowPlanes cooling shroud that uses a 1″ blast tube. So I ordered a 1″ duct flange, some ducting and clamps from Aircraft Spruce and will drill for that when they arrive next week. I had one other task I wanted to get done and that was to plug the two holes on the aft side baffles. These holes are for a socket extension so you can get the spark plug in (I think). Either way they need to be sealed. So I made a cover using some sheet aluminum shaped into a circle and epoxied a spaced onto it to account for the angle that splits the hole. I also cut a couple of sheet for the opposite side. These two pieces will be screwed together and sandwich the baffle sealing the hole. So that’s where I stopped for the day after cleaning up the shop. I’ll get back at it next week after the parts arrive. Now to decide to paint or not paint the baffles!

Baffle Seal Work

Time: 4 Hours

I got to spend a few hours in the hangar today to work on the baffle seals. Before I started on that task I painted the snorkel and the fiberglass oil cooler plenum. I found a spray paint that is very close to the metallic silver on the engine. I really like how this paint turned out and look forward to seeing them on the engine. So now the baffle seals and new silicone material I got form Aircraft Spruce. I made a couple of templates for the aft section and sides to use to cut the silicone. Over a couple of hours I put on/took off the pieces and trimmed them as I went. It took several iterations to get them the way I wanted. I bought a leather hole punch that makes quick work of the attachment holes. I decided that I wanted to use screws vs rivets as the plans called for. I chose to do this so I could easily replace the seals in the future. So I’m happy so far and still have the forward seals to finish. The seals make putting the upper engine cowl on a little difficult as they have now formed to the final shape. I’m holding that will get easier as time goes on.

Snorkel Work

Time: 6 Hours

I have several factors working in conjunction with the baffles that all need to work nicely together as they come together. So I have to work on all these things at the same time to make sure they all fit together. So I took some time to work on the snorkel and it’s fit. I have the brackets that tie the snorkel to the left ramp finished and just need to rivet them to the fiberglass. I don’t want to do this yet until I finish all the surface sanding/filling. I also don’t want to do that until I fixed a contact point and install the alternate air door. First was the contact point where the fuel mixture arm hits in its forward most position.

As you see in the photo the arm hits and needs to move forward another 1/4″ or so. To fix this I decided I would just redo the fiberglass in this area. I marked the spot and cut out the area. At the same time I trimmed the part that attaches to the fuel servo to make it match the servo.

After sanding and cleaning the area around the hole I mixed up some epoxy and applied three layers of cloth. Informed the fiberglass into a cup inboard to create an area for the arm to move into when it’s in its forward most position.

So I let that cure overnight and started working on the alternate air door. The way the engine gets air for the combustion process is through the air filter I have been working on. If I get into a situation where ice or snow were to get into the filter while flying it could clog and block the filter. If that happens the engine could quit running. To keep this from happening you install a alternate way of getting air. This door in the side of the snorkel can be opened in the case of filter blockage while flying. This would allow unfiltered air to enter and keep the engine running. The door consists with a ring that gets riveted to the snorkel and a circular door that will pivot on a screw at the bottom of the ring. A cable will pull the top of the door and slide the door open when needed. I used the ring to mark the spot that I needed to cut on the side of the snorkel.

After cutting the hole and tweaking so the ring sat good I match drilled the holes into the fiberglass.

I strayed away from the plans a little when I came to how to keep the air filter in place. In the last photo you see one of three angle pieces that are used to attach the top section of the snorkel to the air inlet ramp. There is one on the outboard, one on the inboard and one on the aft edges. They have a step shape to them that creates a lip for the air filters flange to rest on. I put nutplates in all three and matched the ones in the aft flange to the baffle ramp rivet holes. Those rivets will be replaced with screws. These screws will serve two functions, the first is to hold the top of the snorkel in place and the second is to hold a retention cover that will trap the air filter between it and the snorkel.

This will make for an easy removal of the filter at the same time securing it well when in place.Once I had the filter brackets fitting perfect it was time to work in the finish of the snorkel. I removed it from the air servo and removed all brackets. I put a skim layer of epoxy/fairing filler to hell with all the pin holes and flaws. After that cured it was a long standing session to smooth it all out. With a little clean up I was able to add a few coats of filler primer. There are a few small spots that require a little filler but overall I’m happy with it so far. Next up will be to rivet the brackets on and paint the final color, I’m thinking a silver metallic to match the inner cylinders of the engine.

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.