Added the glass to the front of this bulkhead.
And then separated the hatch from the fairing and trimmed the bulkhead.
Put it together again and back on the fuselage for a fit check. So far itís fine.
The front of the fairing is about where the cowl cheek bulkhead goes. Iíll need to tweak the aluminum bulkhead, which was just a bit oversize on the right had side, and remove the hatchís fiberglass one.
Before then, though, I laid up the beginnings of the flanges for the aft portion of this cheek extension. At this point, Iím only using two layers of bid and a cover of peel ply, because I wasnít sure how well this would work out. So far it seems okay. I expect to add more when this has cured.
Although I have no photo of it, the aft end has been finished off and after adding a third layer of fiberglass, I trimmed the flanges. Iíve added the flanges on the right hand fairing, too.
Have a great Fourth!
Added the glass to the front of this bulkhead.
And then separated the hatch from the fairing and trimmed the bulkhead.
Put it together again and back on the fuselage for a fit check. So far it’s fine.
The front of the fairing is about where the cowl cheek bulkhead goes. I’ll need to tweak the aluminum bulkhead, which was just a bit oversize on the right hand side, and remove the hatch’s fiberglass one.
Before then, though, I laid up the beginnings of the flanges for the aft portion of this cheek extension. At this point, I’m only using two layers of bid and a cover of peel ply, because I wasn’t sure how well this would work out. So far it seems okay. I expect to add more when this has cured.
Although I have no photo of it, the aft end has been finished off and the flanges trimmed. I’ve added the flanges on the right hand fairing, too, including the area at the aft end. Not shown, they are trimmed. I needed to use a small bit of foam to help shape the aft end, unlike the right-hand side.
After measuring and trial-fitting the battery in the right hand fairing, I moved that cowl bulkhead forward a couple inches. The aft end of the battery didn’t fit comfortably inside the hatch - had to make a flange extension piece to do this. Fortunately there’s room - so far - in the cheek area behind the engine.
Here’s the bottom battery mount. The flange extension is on the right side of the battery inside the cowl cheek itself. The brass nut stack is the pass-through for the ground forest of tabs, which is just inside. The ground forest has two bolts. The other one is into a nutplate riveted inside the cheek extension out of sight.
The red pads are some silicone baffle flange material that I had on hand. I used Pliobond to glue them on, this is a somewhat industrial contact cement that’s been available for probably upwards of 50 years. The two horizontal strips nicely account for the mild curve of the fuselage side.
*** Later - Don't use Pliobond for red silicone! The peel strength is approximately zero. ***
With the bottom mount on, I could not resist seeing what the whole battery mount assembly looks like. The orange dots are the magnets I’m using to hold it all together. These are very convenient and I strongly recommend having a couple dozen of them. You can get them here.
There will be a few changes and some obvious trimming. For one thing, the stack of magnets to the immediate left of the battery is just an aft stop. The battery is an empty dummy. EarthX sells these and it’s been very useful for mocking-up the assembly.
The battery mount is in and the photo shows it latched.
Dan Christian, whom we we know as Dan 57, flew in for a brief visit. He was traveling from Switzerland to Oshkosh and back in his RV-6. This was not a direct flight, with stops all around the U.S. and Canada. Quite an interesting visit, and a very nice RV-6.
The fore-aft battery stops were not yet in. I had added a short extension forward for the cowl cheek bulkhead, and after some time jiggling this and that, got the right-hand cowl cheek bulkhead installed. Here it is with the battery mount open. That stack of magnets between the silicone strips and the ground forest pass-though is merely acting as a temporary stop.
The silicone pieces can be attached reasonably securely with Ultra Blue silicone gasket sealant.
I removed the forward molded-in bulkhead from that RV-4 cowl cheek extension as it was in the way of the battery. Not to worry, thereís plenty of fiberglass work ahead.
Speaking of that, I trimmed off the cowl core from the bottom right-hand cheek area of the cowl for an inch or so, to provide space for the parts that the quarter-turn fasteners on this side attach to. Later I decided to use nutplates for the cowl cheeks.
A small setbackÖ. The hatch did not clear the battery latch. I removed all the stainless latch assembly and replaced it with aluminum and a screw. Everything fits fine now.
Iíve started prepping for the hatch hinges - the upper hinge pin can be removed to open the hatch, but the bottom one stays in place. You can see the upper one in the photo. The bottom one, also shown, needs further adjustment.
It’s been a while since I’ve posted, sorry. I’ve worked on a small variety of things on the cowl and its cheek extensions, making minor progress. Here’s a rough summary.
I figured out an imperfect but satisfactory approach to safetying the hinge pin that’s the battery access hatch lock. It had baffled me for too long. I’d hoped to be able to use safety wire but it appears as if using McDaniel’s safety cable will be a lot easier. Hint, if you’re planning on buying this plane when I sell it, get one of those things; you’ll eventually need it. The red ellipse and arrow identifies the cable and the restrained latch.
I installed the inlet ramps in the upper cowl. As is standard for RV-3B parts, they fit poorly. I used foam to block most of the gaps, and a bit of trimming got me this far. The left hand one fit better than the right hand one. Here it is while still fitting and thinking about it.
For some reason, I had more trouble with the right hand one. No idea why. Here it is at the same stage.
Once I finally decided to press ahead with these, and tweaked and fussed until the lower cowl’s flanges joined okay, I glued the inlet ramps in and after some foam fitting and grinding, used micro to smooth out the joints. After that, a bit of 3 oz. glass over the foam and here we are, with all the ends and edges smoothed and sealed.
I can't say that I particularly like the slopes of the ramps. The right one is steeper than the left, but I suspect that both are too abrupt and steep to be optimum.
It was time to ensure that the cowl cheek extensions were fair to the cowl cheeks. My shop is a small two-car garage and I needed to be able to step back to get a better perspective on this, so I pushed it out. It hadnít been outside since before the engine went on and I added some other things since, too. It was heavy enough and the driveway sloped enough that it was a handful keeping it under control. I should have asked for help from a neighbor, but I didnít. I got the tailwheel up against a handy stump and was glad that I hadnít had that stump removed - itís the only stump I let remain so there was an element of luck here.
On the right side, I didnít have the stand-off distance Iíd have liked, but it was adequate.
Now Iím filling and smoothing the cheek extension fairings where I had to extend the distance they stood off the fuselage, the RV-3B cowl being different than the RV-4 cowl these fairings were made for. Itís the business of adding micro, sanding, adding a touch more, etc. No up to date photos but thatís whatís going on.
One thing Iíve noticed is that in past years, my shop would never get warmer than 80 F. This year thatís not the case. I knocked off today at 84 F. Still, thatís better than outside, where it was well above 90 F. One reason for the higher shop temperatures is that there had been an ash tree shading the windows. It would leaf out in the Spring and the leaves would go away in the Fall, a perfect seasonal sunshade. Like nearly every ash tree in Boulder, it got the ash beetles and died. Had to remove it. Yeah, that was one of the stumps removed.
With the beginning of the school year, I started mentoring an RV-12 project at Boulder High School. I had earlier met with the teacher associated with it and agreed to do that, but later bowed out. Then he got killed on the way to Oshkosh, would have been his first visit there. Turns out the remaining staff have no idea of any of the organization of the project and know very little about it. And I was the only mentor they knew of. As a result, Iím spending some time there trying to get other mentors (volunteers welcome, PM me), finding funding (donors welcome, PM me), arranging for work space (like pulling trees through a keyhole), and somehow getting some organization done. So far itís taking me more than the 2 days a week I signed up for. I must admit that I enjoy this. There has been and will be somewhat of an impact on this RV-3B project, at least for now. I do plan to bow out if and when they are going smoothly.
Still, Iíve made some slight progress. My list of things that need to be done before I can bond on the left cheek fairing is growing but Iíve figured out how to do some of the secondary details which had mystified me, and Iíve made some progress finishing the fairings.
So sorry to hear about the loss of the programs teacher. Thank you for taking the time to mentor those kids. Itís so important that we give where we can and the impact will be more than youíll ever know.
Thank you also for your excellent posts. As one with a disassembled -3 dust collector, reading about your progress pushes me ever closer to banging away again soon.
Been tweaking the cowling. On the left side, the top cowl didnít fair well to the cheek extension, so I cut a slot at the point where the cheek grows out of the cowl, as shown in the photo. Disregard the duct tape, itís gone.
I removed the radius there, and used packing tape on the inside to have something to lay the glass up to. Epoxy doesnít stick to packing tape. I donít have a good photo of it, but at this time, Iíve got the first layers laid down on the outside. To minimize filling, I plan to add more layers on the inside after I remove it.
The lower cowl needed extending at the aft end. I seem to have over-trimmed it. I clecoed on some strips of .016 aluminum that Iíd taped, and used some magnets to hold them in place. After tapering the inside aft edge of the cowl, I laid the glass over this.
It worked out well but I need to reinstall it to trim the new material.
The RV-12iS mentoring proceeds. Thanks, Mark, for your encouragement. It takes more time than I thought. We donít have enough active mentors or tools to work with, but we have started the students on the practice kits which were so generously donated. Students donít get to touch the plane itself until theyíve successfully completed a practice kit, one per student. Some students were getting close and one in particular is doing excellent craftsmanship.
Class meets four afternoons a week but we generally have only one or two mentors per class, but only three classes a week. There are also additional students in a morning class and we donít have any mentors for them, nor practice kits. Iím reluctant to let them at the plane and since Iím not there then, so it will be interesting to learn how this plays out. Basically, I think that we have twice as many students as we can handle in the afternoon session, and a whole class more in the morning session, all more than the resources can presently absorb.
I installed both the upper and lower cowl and the cockpit coaming. Thatís the top that goes over the front of the cockpit. I did this so that I could check that all the lines are flowing about right and it looks like they are. You can see that the left cheek, top and bottom in the back area, needed to be adjusted. Turns out that the gray fiberglass RV-4 cheek fairings are mirrors of each other, but the cowl cheeks themselves are not. The left one was fatter, top to bottom in the back area, than the right.
The hidden cowl latch I planned wonít work. The geometry is wrong for that. But Iím working on an alternate similar idea for that and itís showing promise.
In this next photo, the pad for the new hidden oil door latch is being formed of flox with a layer of BID. The aluminum bar is merely a tooling piece of scrap to ensure that the pads are coplanar.
Since the weather has gotten colder, I brought it in to enjoy the warmth of the house overnight. Thereís another VAF thread about a Zizzo folding bike. Since I was looking for a folding bike, I decided to buy a Zizzo Urbano. Turns out the box it came in is a dandy cowl support tool.
The Zizzo Urbano is a bit longer, folded, than specified, and most likely wonít fit this airplane. It will fit my Cessna 180, but then a regular road bike will too. Once I had three people and three bikes on board but that took some arranging.
Hereís an update on the high schoolís RV-12iS project.
We now have ample funding for the tools and, I expect, some more of the kits. Thatís the big news. I will make sure that we keep some money available for unexpected contingencies, because there will certainly be some.
The first batch of students has finished their practice kits. Some of the students have done quite good jobs. We are making sure that all the students are building airworthy kits, although these practice kits will not fly. Some of the practice kits seem to suffer from the learning curve and while they donít meet that standard, the students have learned from that. The students who finished their kits first and got a passing grade are working on the first airplane parts - yes, weíve started, on the vertical stabilizer.
I started a VAF blog for that project, here. Itíll probably have fewer photos than this one.
After much finagling, I finally got the oil door’s latch installed to the oil door and its area of the cowl. First, I had to build up a suitable pad to attach the latch hinge to, since none of the surfaces were remotely in plane with each other. That included trying to find a suitable spot. The build-up area is just flox but the bond to the hinge is G/flex. Since the hinge is anodized, it needed to be well-abraded.
The hinge was a one-piece thing glued straight across the oil door and its frame. Keeping it one piece ensured that the holes would line up. I used magnets to hold the door closed and to hold the hinge piece in place while the glue dried. The perimeter magnets are still in place here, and the cut lines are marked.
A Dremel with a cut-off disc quickly made the cuts, and a file cleaned up the edges.
Then came the moment I was awaiting…. And the wire went in smoothly. Pulls out easily, too. And bonus, it does indeed hold the door closed with some pressure on it. Here the wire’s shown in with the magnets moved so they weren’t holding the door closed.
The hinge part to the right is the lead-in guide and the wire will always rest there. The hinge part to the left is the termination stop and the wire won’t go past that.
Some clean-up work remains, obviously, and the guides and associated parts to the right of the oil door assembly still need to be figured out and installed. The holes in the latch hinge do not point towards the cowl opening so I’ll need to guide the wire outboard a bit for that. Incidentally, for these photos, up is outboard, down is inboard, left is aft and right is forward. The cowl makes that abrupt bend because that’s where the cheek starts.
Tomorrow's Thanksgiving 2022, and I want to wish all of you a wonderful holiday. We have a lot to be thankful for. Among other things, we live in a prosperous, free country and have the freedom to fly. There have been few other generations that could do this. We're at peace and I especially want to thank the people, past and present, who defended our freedoms, our independence and indeed, our constitution. I salute you all.
Got further along with the hidden oil door latch by making a finger loop at the end of the wire pull and a small flox stop to prevent the wire from going in too far. In the photo, it’s difficult to see the stop at the left end of the piano hinge but you can see the finger loop in the wire and the guide bracket, clecoed in place.
Turns out that in this position, the wire rubs on part of the engine. I’m in the middle of relocating the guide bracket to prevent that - it will move more to the right.
The forward end at the loop (to the right in the photo) is currently unrestrained. I have an idea how to hold it in position, prevent chafing and how to make a forward stop to the wire so it can't be accidentally removed.
Since I’ve been working on various small things on the cowl, it’s a good time to do any adjusting to the cowl’s aft bottom edge for the exhaust. Here’s the bottom aft edge with no exhaust in place.
And with the exhaust temporarily in place, we can see that the cowl rubs on it; it will clearly require some change in contour. Less obvious is that the aft bottom edge of the cowl is not a smooth curve or even straight.
For you engine folks, the exhaust is one of Larry Vetterman’s last RV-3 exhausts before he retired. Here it is from both sides and the center. It’s four individual pipes, no mufflers, no cross-over. The tip turndowns are not on yet. Remember, this is merely a trial fit.
I looked in my collection of RV-3 photos to see how other builders shaped the cowl contour in this area. There is a wide variety of shapes here. It’s definitely worth while accumulating photos of other RV-3s!
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