Cowling Baffles and engine installation
I continued working on the Baffles. I finally finished those up.
This shows the detail at the L/H cylinder. I used .020 7075-T6 aluminum sheet for all of these baffles. That's not a magic alloy, its what I had laying around. It does tend to crack pretty easy, but I guess that's what a stop drill is for.
Support is where you find it!! I made a bracket that picked up one of the case bolts and used it to support the upper baffle. I used clip nuts here so the baffles could be removable.
This shows the detail on the R/H cylinder. Note the cut outs for the exhaust. All around the edge of these baffle plates a blade of silicon rubber will be added. this will make a flexible seal between the baffle and the inside surface of the cowl.
This picture shows the silicon seal added to the baffles. I needed to make a retainer plate for the silicon. This served two purposes. It clamped up the silicon seal and it created a stiffener that keeps the baffles from bending away. I made the retainer by bending some aluminum over a form block.
This is the MDF Form block. note the bend relief cuts all along the edge near an outside curve. When the metal is formed over it compresses along the edge and causes a wrinkle, the slits allow the metal to move and makes it much less prove to wrinkling.
After I finished with the metal work, I made a template for the final trim of the cowl. There is a fly weight that is attached to the aft face of the prop flange that needs to have clearance to the cowl. The old trim was just a rough cut any way.
finally I added countersunk washers to the main cowl fasteners. These will spread the fastener load out over a greater area and allow for a flush countersunk head. I covered the show face in tape and then sand blasted the back side. I countersunk the cowl fiberglass, sanded a small area under the washer and then bonded the washers to the fiberglass. I'm using a cleco with a small washer to clamp the washer during cure.
Engine exhaust and cowl internal baffles.
The next step in getting this engine ready was to fabricate new exhaust pipes. The twin pipes that came with my Casler engine were 90 degree pipes designed to stick out the bottom of the engine. That's pretty crude in my mind and a 1.5' diameter tube creates a lot of drag sitting 6 inches behind the prop in the prop wash. I needed these pipes to snake around inside the cowl and exit on the outlets of the side cheek cowls. I started the project by ordering some pre bent tubes from Columbia Mandrel bending. They did a really good job. I ordered some 180, 90 and 45 degree sections along with a straight section of tubing.
this took some time and a lot of cutting and fitting. the pipes were a 3 dimensional bend. I had to route the pipes under the push rod covers and along side the block. This required multiple bends.
Here are pictures of the L/H and R/H pipes
Left hand Pipe
Right Hand Pipe
the cowl was buttoned up and the clearances checked once again.
nice tight fit. I have good clearance to the fiberglass cowl. I will wrap these pipes in heat resistant insulating tape.
After the pipes were fabricated, I started n the internal cowl baffles. The inlet air has to be forced thru the cooling fins. I started fabrication with a cardboard mock up.
This was time consuming. the shapes are just approximate at this stage of the mock up. have a needle contour gage that is very handy in creating offset curves. The baffle plates will be made from .020" 7075-T6 aluminum sheet. the seal edges will be lined with silicon rubber baffle seal. That will be pop riveted to the aluminum sheet.
here is the lower baffle with the cut out mocked up for the exhaust pipes. you can see the small bent flanges that seal the bottom of the cylinder fins.
I made the first one and them promptly bent the flanges in the wrong direction. Oh well practice makes perfect. I should have the baffles all wrapped up by this coming week end. After that, I can do the final trim and finish on the cowl, I will also install the final nut plates and then prime the cowl once more. The next step will be to finish the engine installation and then get a prop and try and start it!!!
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| raw tubing from Columbia Mandrel bending |
Here are pictures of the L/H and R/H pipes
the cowl was buttoned up and the clearances checked once again.
nice tight fit. I have good clearance to the fiberglass cowl. I will wrap these pipes in heat resistant insulating tape.
After the pipes were fabricated, I started n the internal cowl baffles. The inlet air has to be forced thru the cooling fins. I started fabrication with a cardboard mock up.
This was time consuming. the shapes are just approximate at this stage of the mock up. have a needle contour gage that is very handy in creating offset curves. The baffle plates will be made from .020" 7075-T6 aluminum sheet. the seal edges will be lined with silicon rubber baffle seal. That will be pop riveted to the aluminum sheet.
