Holy Cow-l

Greg and I spent the majority of the day in the Garaggio. Greg mostly worked on baffles, and I worked on wiring and the cowl fit.

For the baffles, Greg had to do a little bit more trimming, then it was locating and drilling holes to secure pieces together and to the engine. In some places we added nut plates to make assembly easier. In other places, pieces were riveted together to make them an assembly. We had to think through the installation and removal process to decide where to use each fastener. Additionally we added doublers around some of the mounting fastener holes. These were supplied with the vans baffle kit, and should extend the life of the baffles. It was a long tedious process for Greg today because it was a lot of drilling, disassemble, deburr, dimple, rivet, reassemble, and do the process again on another part. Good news is we made a lot of progress on the right side baffles. Left side is similar and should go faster.

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In between helping Greg with baffles I worked on more wiring, the rest of the fat wires in the engine compartment. This included the positive wire to the starter (it is grounded though the housing, and grounding the engine case to the rest of the airplane. Pretty simple, just 2 wires to plan a routing, terminate, and install. I am happy with the routing, and once the wires are secured with clamps and zip ties, they will look nice. I even pulled out the multi-meter and verified that we had ground on the alternator and starter housings as well as +12 volts from the positive terminal at the firewall to the starter case and alternator case.IMG_3295

Then I started in on something that is just annoying. Cowl surgery number nine thousand four hundred and eighty seven. There is not enough clearance between the exhaust and the cowl. So no choice but to make more room. So it was get the sanding drums and die grinders out and make it into a… Holy Cowl.

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Before the holes, 2 of the 4 exhaust pipes were resting on the cowl and one was within 1/8″ of the cowl. This is obviously not enough, you need at least 1/2″ or more. Even at 1/2″ it could be close enough to burn some paint. Only way to know is to fly and try it. I do plan on shielding this area with an insulation which should help as well. Now that the damage is done, I am committed.

Now to add more room for the exhaust pipes. I added 1/2″ of green foam to the outside contour of the deficient areas. This will become my sanding indicator. I hot glued them in place so that they don’t move.

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Then it was add some pour foam.

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Get rid of the excess and shape to a pleasing contour being sure to stop before you get into the green foam. It is easy to see when you are getting close. You just have to remember to stop or you will negate the purpose. I had to add a second pour on both sides around the aft edges to get the shape I was looking for.

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All in all, I think the shape will turn out just fine. I think in some ways I actually like the new shape better. We will see when it is all finished and primed. It may be a net zero on drag because it is a smoother shape with less retreating angle, and the radius of the surface intersections is larger. No way I will ever know since I have no before data, but makes me feel better thinking I’m not adding a ton of drag to my airplane.

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Then I took my Festool (yes Jon, a power tool) sander to the area around the “repair” to get down to pure carbon fiber. Bonding to the micro filler, and primer is not very structurally sound and is a big no-no. One side is basically ready for a carbon layup, the other side needs to get down to pure carbon yet. Once the exterior layup is done, I will dig out all the foam and carbon from the inside and do an interior layup.

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That is pretty much where I had to leave the project for the day. One more day off before a block of work.

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