The last couple of weeks have been fairly busy, as I was on course for several days, which required some studying in the evening. And I had to take care of a few things on the Honey Do List.

In my spare time, I've knocked a few items off the To Do List, and added a few more, for a new change in length of the list of about zero. I've been flailing away on the interface between the cowling and the plenum chamber. I'm making progress, but each time I mentally tell myself that I have turned the corner, and all the hard work is done, I run into another snag. I've had to back up and change course several times, but I am slowing grinding closer to the end for the right side. I won't start the left side until the right side is nailed down, but I expect the second side should go much quicker than the first one.

I've already decided that I should have used a different type of fastener for the plenum chamber. At the moment it is held in place with about 40 #8 screws, which will take some time to remove and reinstall every time I want to inspect the engine. I should have used some sort of quarter turn fastener, but I won't make that mod now. That'll be a change I make after I get flying.

The basic concept is a strip of aluminum that will be riveted in the inside of the upper cowling inlet. A fibreglas transition piece will attach to that strip with three screws, and a long piece of inner tube rubber will go from there to the plenum chamber. This should provide a relatively good seal, while allow for motion between the plenum chamber (which is fastened to the engine) and the airframe. The sides of the rubber seal will be fastened to the vertical pieces of the plenum chamber sides, and the top will attach with four screws to the top of the plenum chamber. The edges of the inner tube will be sandwiched between pieces of aluminum sheet. The rubber inner tube pieces and fibreglas transition piece will remain in place when the plenum chamber top is removed.

I'll be trimming the front part of the plenum side walls, as I only need enough material ahead of the aft edge of the rubber to provide structural support for the floor of the inlet.

It's been an eventful few days. Terry got into a car accident on the 401 in Toronto Wednesday afternoon. She wasn't hurt thankfully, which was quite amazing considering there were two semi-trucks involved, and her car got munched by one of them. Her car probably won't be repaired though, as it looks like the repairs would cost more than it is worth. Thursday I drove to Toronto and back to rescue her. The big power blackout started while we were driving back home. As soon as we figured out what had happened I slowed down to economy cruise, and we coasted into our driveway with the car running on fumes.

After we got home I pulled the generator out of the garage, but I couldn't get it to start. I pulled on the starting cord until I was ready to have heat stroke but it wouldn't fire. It hadn't been started since the Ice Storm of Jan 98, when we went ten days without power. Geez, I guess gasoline (winter gas at that) doesn't last 5 and a half years. It sure didn't smell like gas when I opened the tank.

The power came back on at 2:50 AM Friday morning. The federal government announced that all non-essential employees were to stay home on Friday, so I did. I headed to the local gas station to fill the car up, but they didn't have power. The next gas station had power, but the unleaded fuel ran out just as I arrived. They had already run out of mid-grade, so the car and jerry-can got filled with premium fuel. The generator and lawn mower should really purr now.

One of the Canadian Tire stores was open, so I managed to buy some carburetor cleaner. The carb on the generator was really gummed up from the remains of the gas from 1998. But, after I cleaned it and replaced the gas in the tank with the fresh premium I had just bought, it started right up.

Friday afternoon and Saturday we started shopping for a replacement car for Terry. I really, really hate car shopping.

It took forever for the Proseal under the cowl hinges to cure, so I couldn't do a trial fit on the cowl until today. I was worried that the thickness of the Proseal would screw up the fit, but it went on perfectly.

I bent the forward end of the hinge pins so they wrap around the shank of a countersunk #8 screw, which will go into a platenut to secure the hing pins. I'll cover the screws with nice stainless steel covers made by Dale Lamport, a prolific local RV builder. Thanks Dale!

I've been messing around with the oil filler door the last two days. It is a simple piece of flat fibreglas, hinged at the top with a piano hinge, and with two wingnut CamLoc fasteners at the bottom corners. It all went well enough, once I shaved away a bit of fibreglas to allow the male part to go deeper into the receptacle. The door is all ready to rivet to the hinge, but I think I'll hold off on that a bit, the hinge pin can't be removed once the hinge is riveted in place - I would need to drill out the rivets if I need to remove teh door for some reason.

RMC 20 year reunion - I just got back from three days in Kingston at my RMC Class of 82 20 year reunion. There was a very good turnout, and it was great to see everyone again. It's hard to believe that it has been 20 years already.

Cowling - This week I put in and sanded some more filler to help match up the two cowling halves at the front. There is still a bit more filling to do to fill in small low spots, but I'm getting pretty close. Then I countersunk all the holes for the rivets that will attach the pieces of hinge to the cowling.

This week I put in some filler to help match up the two cowling halves at the front. I did a couple of rounds of mix and apply filler, let filler cure, file and sand filler, remark upon low spots that still remain, or areas that were missed last time, repeat. My parents are visiting from Nova Scotia this weekend, so I've been spending time with them instead of building. I get a short building session in early in the morning before everyone else is up.

This week I had to build up the edge of cowling a bit in three places where I trimmed it too much. I'm using West Systems epoxy fibreglas - I mixed some West Systems 403 Microfibers in with resin to make a very thick slurry. I roughed up the edge of the cowling, and clecoed a strip of aluminum covered with tin foil to the outside of the cowling to be sure I got a smooth transition between the surface of the cowling and the added material. I wasn't sure how good a bond I would get to that thin edge of the cowling, but it seems be a very strong bond. I also had to build up the flat area behind the spinner to get an even gap. I've still got lots more filling and sanding to go yet to get a nice match between the two halves of the cowling at the front.

I tried something a bit different when I fitted the two pieces of hinge at the back of the top cowl half. These pieces of hinge make a continuous curve, due to the fact that the top of the fuselage is rounded. The hinge is designed to take a 1/8 inch diameter aluminum hinge pin, but the plans say to use a 3/32 diameter stainless steel hinge pin instead, as you must be able to pull and replace these pins to allow the cowl to be removed, and it would be impossible to push a 1/8 inch pin around the tight curve at the outboard edges of the top cowling. Even so, many builders report that it is difficult to insert the hinge pins. The instructions have you use the smaller 3/32 hinge pins when you are drilling the cowling to the hinges. But, this means that there is some slop between the two halves of the hinge, and thus the eyes won't be perfectly lined up, which might explain why the hinge pins would be difficult to insert. I decided to leave the 1/8 inch aluminum hinge pins in place when I drilled the hinges to the cowling, to ensure the hinge halves were perfectly aligned right from the start. Today I cut the 3/32 hinge pins, and tried them out, inserting the two halves of the hinge pin by reaching in through the oil filler door - they slipped right into place without any difficulty. Mind you, the hinges were only clecoed in place, I hope everything is still nicely line up after I rivet them.

I worked hard to trim the cowl to get an inlet height of 2 3/4 inch. I got the height set, and I fitted the cowling a bit low at the front, as most builders report that the engine sags a bit after the aircraft flys a few hours and the rubber engine mount bushings take a set. I hope that engine sag happens fairly quickly, as I don't have much clearance between the top of the valve cover on the front left cylinder and the cowling.

This week I finished trimming the lower cowl at the firewall, then drilled the bottom and sides of the lower cowl to the hinges. Then I trimmed the edges at the horizontal line where the top and bottom cowl meet. Then I drilled the cowl to the two pieces of hinge that go at at that horizontal split. I also cut out the opening for the oil filler door.

This week I've been working on the piano hinges that are riveted to the sides and bottom of the fuselage at the firewall. I discovered that I had made a big foul-up when I drilled the fuselage skins to the firewall. I had simply marked a line on the centre of the firewall flange, just like I did on all the other bulkheads. The result was that the edge of the firewall flange stuck out past the forward edge of the fuselage skins. I thought this would all be covered up by the cowling, but I didn't realize that the cowling, which is thicker than the fuselage skins, simply butts up against the fuselage skins, so the firewall flange must be flush with the edge of the fuselage skins, or it will interfere with the cowling. The firewall can't be removed now, so I was stuck with a tricky and tedious task of filing down the stainless steel firewall flange. At first it seemed like an impossible task, but I finally made progress by using a good quality file, a cutting lubricant (Boelube) and heavy pressure on the file. Not a fun job.

After the firewall edges were trimmed, I dimpled the holes, dimpled the hinges, riveted them in place, then fabricated a means to retain the hinge pins in place.

I spent a bunch of time studying cowlings on 7 Sep 02 at the EAA 486 RV Fly-in. I noted one thing that is worth thinking about if you want to reduce drag - there was quite a bit of variation in how high the air inlets were. Van used to specify the height of the air inlets as 2 5/8 to 2 3/4 inches - the plans were later amended to remove this dimension. I didn't have a ruler with me, but it was quite clear that many RVs have air inlets that are quite a bit larger than what used to be called for on the RV-8 plans. These RVs also had quite a large flat area extending above and/or below the spinner, which also supports my theory that their cowl halves weren't trimmed as much at the front as Van intended.

So what, you ask? Well, if the height of the cooling air inlets is increased, the amount of air that goes into the cowling increases. If we look at the aircraft as our frame of reference, all this air has to slow down to pretty close to zero speed. Or, looking at the earth as our frame of reference, all this air has to be accelerated from a stop to the speed of the RV. This acceleration requires a force to be exerted on the air by the aircraft, and this force is felt by the aircraft as drag.