Rear Bellcrank Assembly Finished

The bellcrank assembly is finished now. I had to thin the washers (instead of using thick ones--Andrej at Pipistrel would like to know why I had to do this, but now it'll be difficult to measure the parts) by sanding them.

The red marks are mine, put there while trying to get the parts lined up so that I could put the bolts through. I had to use a small inspection mirror to see into the bolt hole, to get the final washer aligned. Working into a small opening like this was far from convenient.

I have since put red paint (supplied in the kit) onto the nuts and threads of the bolts, to make inspection easier. I'll be able to tell just by looking whether anything has moved. This bellcrank assembly will be covered by the lower rudder hingepin assembly, though there will be openings to look through, for inspection purposes.

Lots of work yet to do in this area, but securing this bellcrank assembly was a milestone.

I'd be happier if the vertical pushrod didn't "pull" over to one side as much as it does. I even loosened the upper bolt again (overcoming red threadlocker) but it remained the same. I don't think it'll hurt anything. I tightened it down again with a new drop of threadlocker.

This is at the bottom-rear of the vertical fin. The stabilizer and elevator will be mounted at the top of the fin. The Sinus is a T-tail motorglider.

I Was Quick

About a foot of snow fell last night, and my Prius was in the garage. My 4wd truck isn't here now because it hit a deer and is being repaired. Was I stuck for several days? No time to lose.

I got my snow shovel and started digging. After some work, I had it so I would be able to back my Prius out, and get it pointed toward the driveway. There were still some tracks, though mostly filled, in the driveway. I dug one out almost to ground level.  Then I went along the center section and shoveled away a swath of snow. I just didn't want the bottom of the Prius to drag. It's low-slung. I dug the other track, having marked it first by walking it. There was now a wall of snow on each side of the center swath, which I knocked the tops of into the center. I had a driveway again!

Then I drove the Prius out that driveway and parked it on the county road! I was done. As I walked back to the house, the wind began to blow. Had I waited even half an hour, there would have been big wind, blowing the snow, and undoing what I'd just done. Now, by the end of the day, my driveway is drifted shut again. Not light and fluffy anymore, it would be difficult to shovel. But my Prius is parked out on the street and that's a very good thing! Nowhere to go in particular, but I'm ready.

Tool for Sanding Washers

This is a tool to help me sand the washers to make them thinner. I found a piece of wood and used my router to cut a shallow depression the size of a washer. Then I could sand the washer without it moving around. I'd been doing this another way--pressing the washer down onto sandpaper and moving it around with a small piece of plastic I had, but that piece of plastic was wearing out. So I made this and finished the job with it.

The white material here is sawdust from the sanding. The lower depression is one that I'd made first, and not very well. The edges of it broke up quickly. Then I made the depression where the washer is.

Help from Pipistrel

While trying to figure out this washer-thing, wondering whether I was overlooking something simple, or was maybe using the wrong parts, I sent an email to Andrej Horvat at the Pipistrel factory in Slovenia. Andrej was very helpful as he always is. He sent me back an email telling me the exact sequence of parts that go onto that bolt. He sent me measurements of all the pieces, trying to get to the cause of the problem. I never did figure it all out--my dimensions seemed correct--but I did find a way to get the job done.  It's great to have such support from the factory when working on a kit like this.

A Difficult Thing

This had to happen, but it was sure hard--the connection of the upper pushrod to the bellcrank assembly. The bolt that is visible goes through one side of the pushrod end, then through a washer, then the bellcrank, then another washer, the other side of the pushrod, a washer, and is secured by the nut. The problem was that one, but not two, washers would fit. That's not enough! There's a bearing in the bellcrank and it needs a washer on both sides of it so that it's held fast while the bellcrank moves around it, working the elevators which are atop the vertical fin. Note the small space between the bellcrank and the sides of the pushrod. That's where the washers are.

Something was wrong dimensionally.... I needed thinner washers, not thicker ones as the instructions seem to say. So I bought some at the hardware store in town, hoping they'd fit right in. I'd noticed that in the box at the store, some washers differed in thickness. I bought six of the thinnest I could find there, but they weren't thin enough. I had to sand them down quite a bit until finally I got 'em both in place and got the bolt through!

I'll have to do the same thing for the bottom fitting, but I knew that I'd have to do the top one first or I'd never be able to reach it.

It was crowded work, and blind in many ways. I couldn't see into the hole to find out whether parts were aligned--until I thought of using my small inspection mirror. Then I could see where the second washer was, and could tug it around with the short end of an Allen key. Then the bolt wouldn't slide through--I think the bearing was turned just a bit. I put in a similar bolt from the other side and that straightened things out. Then I removed the second bolt, loosened the piece of tape that was holding the first bolt in place (not letting it fall out, making me start all over), and was slowly able to work the bolt in place. I'll loosen it to apply some red Permatex to lock it in place, but it's not coming out anymore!

Then I'll be able to do two or three other jobs in this same area, getting on with things. These washers have been holding me up for days.

Still Not Working

Today I went to the hardware store in Buena Vista and bought washers. I realized that I needed a somewhat smaller size, and thinner if possible. Well, looking through a tray of washers, I noticed that some were much thinner than others! So I picked out six of those, thinking they'd work fine.

Well, they don't work. They're still too thick, so I guess I'll need to sand 'em down to be thinner. I do this by putting a piece of sandpaper on the bench, and sliding the washer around on it, moving it with a suitable object such as block eraser, or a piece of plastic. With enough work, I think I'll make it although I'd like to know why it isn't working as planned. It almost works, but not quite.

Doing this stuff, I'm thinking in metric but having to trash my mind sometimes by thinking in our traditional system. Bah.... The washers, I calculate, have to be about 0.7 mm thick.