A little Elevator Work

We flew up to St. Louis to visit friends and family for the Memorial Day weekend. So, of course, nothing to report there. Except that every cross country trip reiterates the reasons for this airplane: it's speed, comfort, the advanced avionics, and it will do it all a lot cheaper than renting. This last flight back could have been cut by almost an hour! Can't wait.

The plans call out for solid rivets to attach the elevator skins to the small aft spar. This is fine where it's cut out for the trim tab, but where the skin extends beyond spar...not so much. Access to the area is really difficult especially when the upper and lower skins come together. The plans tell you to make a special bucking bar to reach inside the skins or just install with blind rivets on this one side. Well, I decided, after looking at the strength values of the rivets, to just install both sides with the blind rivets. Primarily so both sides look the same and it will be a lot easier. Plus there is no risk of damaging the thin skins.

With that I proceeded to install the MK-319-BS blind rivets and discovered they are slightly oversized. The #40 holes are a little too small. What I really needed was a #33 hole, but after scouring town this drill bit is nowhere to be found. So I settled for a 3mm drill bit...pretty close. Tried it on a piece of scrap and it's perfect. I opened up the holes in the elevators and popped the blind rivets in. They work great and it was real easy. (0.5)

Elevator Ribs

I finished back riveting the ribs to the elevator skins. I love back riveting it's quick, easy, and the parts come out looking great. I then riveted the aft spar on. All in all, a quick yet productive evening. (2.0)

Elevator Work

The doublers that install around the trim cable cutouts stiffen the elevator skins and have several nutplates installed. The nutplates rivet holes need to be dimpled. So I had to modify one of my dimple dies by grinding down one of its edges to clear the back side of the nutplates. It worked well and the doublers came out great. I then began backriveting the ribs to the skins, but I'll have to finish that maybe tomorrow. (2.0)

Elevator and Trim Work

This past weekend I worked on the elevators and trim tabs. The trim tabs have a lot of detail work to them for such a little part. You have to bend the edge tabs in and finish bending the skins themselves among a few other things. Both the elevators and trim tabs have foam ribs in them to stiffen the skins. The skins need to be scuffed and masked before they are primed in the areas the ribs will go. So I finished the trim tabs, scuffed the skins, and primed the last parts. After a few minutes in the warm sun the parts were dry and I started final assembly of the elevators. Fri (1.0) Sat (3.0) Sun (6.5)

Trim Tab Hinge Pin Solution

I was reading ahead in the plans and found that they secure the trim tab hinge pin to the spar using safety wire. This is probably ok, but I feel it would need a close inspection before every flight to ensure that the safety wire isn't corroding away or wearing through. I've seen safety wire wear through on a Cessna 172 door and would hate for this to meet the same demise. I wanted to come up with something a little more permanent. So I went to the Van's Airforce website which is a forum for RV builders to discuss....well almost everything airplane. With a quick search I came across a solution that I like...reposted below.

This will be my plan, simple.

 

"I struggled with finding a way to secure the hinge pin on the elevator trim tab until I saw this technique used on some RVs that I looked at up at Air Venture.

As supplied in the kit, the hinge is longer than what's needed. When you trim the hinge to length, be sure to NOT cut the hinge pin. Leave it long and extending past the end of the elevator as shown above. Now bend the hinge pin so that it will lay across the web of the spar.

Take a spare piece of hinge and cut out one eye. Drill a hole in it for a #6 screw. Slip it over the hinge pin and locate the position of the screw hole in the web of the spar. Remove everything and attach a #6 nut plate behind the hole. The nut plate will fit on the forward side of the elevator trim spar web where it extends past the edge of the inside elevator rib. When you're done, you'll find that you will be able to get a long bladed screwdriver on the screw even with the trim tab mounted and in-place.  "

Trim Tab Jigs

The trim tab mounts to, and is part of, the elevators; so I still consider this elevator work. It's notable though, how many jigs and fixtures need to be made to make, or finish making, the pieces for such a small part. I made a jig last night to make the trim tab clamps and I continued this jig fashion into tonight to cut out the foam ribs that go inside the trim tab. I wanted to ensure a good perpendicular cut, so, enter the jig. Also you need to make a homemade brake to finish bending the skins from some 2x8's and hinges. It should work well for what I need. So hopefully I can get back to airplane parts instead of building things to build things! (1.5)

Back to Elavators

Didn't get much done today. I cut out some support clamps to help make the trim tabs. I made a make shift jig to help in making them all the same when cutting them out on the table saw. (1.0)

Completed Structure Overview (127.5hrs)

I completed another part so I'm updating the Completed Structure Overview. Below is a picture of all the aircraft structure, if its highlighted blue it is finished and red is in work.

Total Time 127.5 hrs

Finished Horizontal Stabilizer

Today I finished a big part, the horizontal stabilizer! After hundreds of rivets and hours of work it is finally done! I hung it up on the loft when I finished for safe keeping....ok for display too. It was a pretty cool part to build; having the wing shape made it look very airplane.

I am really happy having the pneumatic squeezer, when you can use it, (ie when the yoke can reach the rivet) it speeds things up a lot over installing all the rivets with a rivet gun. For instance in the pictures is a view looking down the length of the stabilizer and it has clecos sticking out reach side in every other hole. Using the pneumatic squeezer for this made the job go by a lot faster. All the other rivets though were done "by hand" with the rivet gun; turned down low and a couple quick hits with a perfectly squared up bucking bar and the rivets came out just right. Building this airplane is really getting fun. (6.0)

Riveting Horizontal Stabilizer

I worked on the horizontal stabilizer a little yesterday, attaching the front spar to the nose ribs using blind rivets. Today I had more time and even though there are a lot rivets to hammer out it goes pretty quick. I made it through a little more than half way. I hope to finish this thing by tomorrow!
Fri (1.0) Sat (4.0)

Stabilizer Nose Ribs

I installed the horizontal stabilizer nose ribs tonight. It was easier than I thought it was going to be, since you have to hold the bucking bar deep down into the skins and rely on feeling to be sure your set up right. I took my time and turned the air pressure down to 50psi. All the hits were square on and as easy as possible. No dents, dings, or scratches! Then I clecoed the skins to the rib assembly and spar. Next step is riveting all of that together...that'll take a while. (2.25)

More Tools

I cut the grass today so I didn't get any work done on the airplane, but my new tools came in! I ordered 50 more 3/32 clecos, new countersink bit, and new 3/32 dimple dies.

Little Stabilizer Work

I only got about an hour in today, but I riveted the ribs onto the forward spar. So far almost all the rivets have had to be installed with the rivet gun instead of the squeezer, due to the size of the spar flange. Not a big deal but it requires a bit more concentration to smash the rivets just right without damaging any if the structure. (1.0)

Restarted Horizontal Stabilizer

With my remade parts primed and ready I could start, again, on the horizontal stabilizer final assembly. Tonight I just riveted the spar and doubler and started on a small rib assembly. Sorry no pics, my phone died while I was working. (2.0)

Busy Weekend

The horizontal stabilizer replacement parts were on my porch when I got home Friday. Which was great news, it kinda set the pace for the weekend. You see, if I finished the elevator parts then I could remake the replacement parts for the horizontal stabilizer and prime them all at the same time on Sunday. So Friday night I got going: deburring, dimpling, and countersinking. This carried into Saturday and then into Sunday. There are a lot of little parts to the elevators. I even had to make up a new tool to fit into the small opening of the aft spar. I made a mini dimpler from a small c-clamp. I drilled out the screw and bottom to accept the dimple dies and with a hard twist you got a dimple. I drilled out the new replacement parts, carefully using the spar as a guide. They came out well and nothing was screwed up on the spar, so success! I then moved onto scuffing with MEK and priming the parts and finished a little before dark on Sunday night. I didn't prime the elevator skins due to some steps that I want to do in tandem with building the trim tabs. But for now, I can start the final assembly on the horizontal stabilizer!

Fri (1.75) Sat (4.75) Sun (7.0)

Elevator Deburr

It's amazing how on some steps you fly right thru them and your off to the next in no time. Then comes along one like Step 8 shown in the picture, sure it's only a small little sentence...then several hours later your still deburring and cursing that "little" Step 8. (2.5)

Thanks Mike for the help getting through Step 8!

Elevator Marking

I took a while and read the plans tonight to be sure of some upcoming steps. One thing I found out was that I need to buy another set of 3/32 dimple dies. Apparently, a set needs to be altered, shaved down, to dimple some nutplates. Since I don't want to do this to the only set I have I need to order some soon.

Most of my time went to disassembling the elevators and part marking. (1.75)