446 hours - Let the rolling begin

There is nothing like a complete computer melt down due to a virus and tax season to put a damper on your efforts to build an airplane. It's been a rough week all around, but I am back in the saddle and have a few pics from last weekend to get caught up on. I basically started rolling the leading edge of the right elevator and also did some prep work for drilling the center bearing bolt holes in the control horns once the leading edge work is done.

First thing is first - I needed to kerf the leading edges of the top skin on both elevators by using the edge roller tool. Same process as when I did it for the rudder. If you can look past all the smudged finger prints, you can see the small crease in the leading edge where the tool did its job. This is important for ensuring that the overlapped skins will rivet together cleanly, without curling up at the edges when the rivets are squeezed.

The idea is that you want to kerf the top skin so that when it compresses down on the bottom skin underneath the two edges will mate together nice and flat. The top needs to go on the outside to help shed water that may accumulate on the leading edges from rain or slush on those less than perfect weather days or when you need to wash the airplane.

the bottom skin needs to be primed where the skins will overlap. In the event that any moisture does penetrate this area you want to do your best to prevent sources for corrosion. Since this is a common area where corrosion can occur iit is in your best interest to apply some form of protection here. My advice is to wait untl after you bend the leading edge, because when I put duct tape over the leading edge with the primer to roll the edge, most of the primer got lifted off by the tape when I removed it. I need to go back adn see how I did this for the rudder because I don't remember having this problem when I worked on it.

Oh, well,  just have to respray it this weekend adn close everything up.

Now, in this next pic, can you tell if it is cold outside or not? I'm sure the hat and heavy coat don't give it away at all! BtW, this was in the garage with the heater cranked up full blast and the insulated garage door closed. Yup, it was cold. Wasn't goin to let that stop me though. I am taping up the bar on the mid section of the elevator in this next pic. Those that follow show the end result:

I decided to try some different techiques this time from the way that the rudder was done. Namely they were:
- I did not use the fancy bend table or the U bolts to hold down the bar on the table while I cranked on the bar to roll the skin. I ahve seen too many pics where everyone just tapes it up adn starts cranking, adn it all seems to turn out fine, so I thought I would try that approach. What I found is that you still have to be very conscious about pushing down and rolling at the same time so that you do not crease the skin where it joins the flanges of the forward spar.
- I did NOT want to roll it so far that the edges of the skins were already perpendicular to the spar before I even start closing them together. This got me into serious trouble with the rudder, because the inside skin ended up being rolled too far, aand I may still decide to open it up adn try to correct it a bit. But for now I will try to get the elevator skins right on the first attempt.

In fact, it turned out that even though I thought I had only rolled them just far enough, the inside skin still ended up being a bit over rolled. Personally I would say that you only need to roll the leading edge so tyhat it sits about 30-35 degrees up when you remove the bar and the tape. Don't even take it to 45 degrees or you will ahve the same problem I do. It really takes a lot of hand contouring the skins to get them to close up adn to ensure that the edges are laying flat against each other.  SO less is more for this part of the operation.

- I did find as others had told me that the elevator skins a re a bit easier to work with than the rudder. The technique to finish the rolling by hand is still an art form, however, and I can't even really describe how you need to do this very well. It is a combination of using the upper pad of the palm of your hand and the bottom portion of your fingers to gently and slowly push the initial bend of the skin closed until you finally reach the mid point where the top and bottom skins will overlap. The rest of the technique is figuring out how to push UP AND AWAY on the skin to keep it from forming a crease where the spar flange edge is located under the skin. Best way to describe this is to take it slow, and work up and down the entire section of the rolled skin. Then, when you think you have it just about right, keep bending it and rolling it with your hand some more so that the skins overlap each other, and only mnimal pressure is required to push the two skins together so that the rivet holes line up. I think that the whole trick to this is finding the sweet spot on the skin where you can apply pressure to keep bending it closer toward the mid section without risking
creasing the skin where it joins the spar flange.

Other than that, you pretty much just have to do it to understand how it needs to work.

-Roll only one section at a time. Yes it takes a bit longer to do this, but it is easier to roll smaller sections at a time.

-  I decided to use a smaller diameter piece of water pipe for the bottom skin, adn a larger diameter bar for the outer skin. I do like how this worked out. My outside diamters were 3/4 " for the inside skin (bottom), and 1 1/8 " for the top or outside skin. This seemed to position the top and bottom skins in such a way that allowed them to form better as you close each one up by hand.

-  I used gorilla tape to roll the edges. Be warned - it will remove the primer on your leading edge - very strong stuff that gorilla tape.

Next pic is about ready to flip the skin over adn roll the bottom mid section of the right elevator.

 The bar gets positioned against the skin so that the skin overlaps the bar by about half the diameter of the bar, or a bout half way across the bar for short :) Then you flip it over so the bar is on the bottom, attach some locking pliers to both ends, and crank away formly and consistently.

The only other thing to comment about is the length of the bars to use. This will be different for the rudder and the elevators, but about 20-22 inches seems plenty long enough to handle any of the control surfaces that need to be rolled. You need to have just enough bar hanging over the exposed cutouts where the rod end bearings are installed, but not so much that it extends beyond the other side of the cutout.

Here is the top section, which is the easiest to put together. I recommend doing this section first to give you an idea of what it will take to do the other sections.

And another important pic to illustrate the fact that the more help you have to perform this step, the easier it is to get it done. You mainly need at least one peson to hold down the skin on the back side becaue you need to move the taped bar assembly far enough forward to be able to attach the locking pliers to the bar to get a good roll. I found that I needed to start the roll, and then reposition the pliers again to roll it just a bit more. If nobody is holding the part down, the heavy bar will flip the whole thing right of the table and you will calling Vans to order more parts. My son Adam was gracious enough to help me with this.

And after both sides are rolled - the center and bottom sections are almost together. The remaining hand forming will close the gaps that you see and align the rivet holes so they can be clecoed together.

This next pic shows what happened to my primer when the tape was removed. Also shows that the edges were still a bit over rolled.

444 hours-Final Trim tab work

Yesterday I performed the bend to the bottom forward skin of the trim tab which is required in order to clear the bottom skin of the elevator, the shop heads of the bottom of the rear elevator spar, and the rear spar itself. As the trim tab moves down there must be enough clearance to prevent the trim tab from binding in these surfaces. There are not many posts or information about how to perform this bend, but one thing is for certain, you do not want to crease the skin so sharply that you risk cracking it, and you do not want to bend it too close to the rivet line either.

SO I came up with the plan to use a piece of 3/16 inch piano wire that I had laying around. I use it for landing gear legs on RC models. The wire was long enough to extend beyond both edges of the trim tab. I set the trim tab in between two pieces of wood so that I could make a recess for the control horn on the bottom, and then I clamped the piano wire up against the trim tab spar web and the bottom trim tab skin. The wire gave me a bit of a radius from which the skin could bend around so that the bend would not be too sharp.

Once everything was clamped down I simply lifted the rear end of the trim tab, keeping the leading edge as flat on the boards as possible,  and bent the leading edge of the bottom skin just enough to ensure that it would clear everything. Came out not the greatest but good enough for me.

The above pic kind of gives you the clue as to why you need to bend the bottom skin. Eventually it will come into contact with the bottom of the elevator and the rear spar. The only question is how much of a bend is needed? This is largely trial and error here and Van's offers absolutely no information about this whatsoever in the plans, except for the picture of the bend and a note that says to bend it.

I also drilled out and reset the two flush rivets holding the corner of the rear spar adn the E705 end rib. They did not set very flush the first time. I may have applied too much primer in the countersunk holes in the rear spar, or perhaps I did not countersink them enough, Once I drilled them out, I countersunk the holes a bit more and then reset two new rivets. The new ones turned out mucho better. You can just see the heads on the right side of the above pic, along the vertical spar web on the end of the spar.

If it bends too far down, the control horn of the trim tab will contact the bottom skin of the elevator, so you know that allowing the trim tab to rotate down that much is going to be too far. The reality is that Van's indicates that the range of motion for the trim tab is supposed to be 25 30 degrees. However, there are  many posts on VAF that confirm that the actual range of the electric trim servo is well short of this mark both up and down. Apparently Van's has even provided clarification, as well as others that have completed their airplanes adn ahve been flying them for quite some time now, that you don't need that much travel for the normal operation of the aircraft. Using my digital level, I determined that my up travel is about 25 degrees, and the down travel is about 19-20 degrees.

This next pic shows the down travel allowed after the bend was completed at the point where the bottom skin contacts the rear spar. This is way more than 30 degrees.

Tonight I decided to install the trim servo, adjust the threaded rod for "level" trim, and then ran the servo through its range of motion to check for clearance of the rod and clevis assemblies with the elevator skin. I found it interesting that running it through its full up and full down range did not really cause much interference with the exit hole on the bottom of the elevator skin. I will still need to do some trimming but not very much. Others have had to trim away quite a bit of material to allow the free travel of the rod without digging into the elevator skin for some reason, but I am not seeing the need. The clearances are very small, but they are sufficient I think.

First pics are with trim tab full up, then full down, and then in level position. Remember that the elevator is turned upside down during all this, so up is down and down is up! I also show my magic trick for connecting the servo wires to the 9 volt battery and running the supplied switch to move the servo. Quite the balancing act....

BTW, the stop nuts on both ends of the clevis require a 1/4 inch wrench to secure and hold them in place while you screw the clevis in or out as needed to set the level position of the trim tab. This can also be fine tuned after you start flying if you determine that the original level position is giving you something other than true level trim of the elevator in flight.

Next pic shows that the rod is just barely contacting the elevator skin on the edge of the exit hole. Maybe 1/8 inch or 1/4 inch more clearance will be sufficient. Clevis on the control horn of the trim tab is very close to the elevator skin, but it still clears.

And now for the down pics

The above pic shows several things. Note how the push rod still favors the right side of the exit hole duw to the misalignment of the control horn with the center of the precut exit hole in the elevator skin. See my extensive previous posts about my concerns with this. Now that the trim tab is fitted and hinged to the elevator, and the trim servo is installed, I am satisfied that any stress on the trim tab servo is minimal. It was only offset about 3/32 inches anyway, and there seems to be enough "give" in the assembly to the point that this is not a concern. Also notice how the clevis on the control horn strongly favors one side of the horn. This is actually drawn in the plans from Van's, and shows the same installation picture with one side of the clevis placed firmly up against one side of the clevis, with a sizable gap appearing on the other side. I guess this is the way it is supposed to be.

And finally some pics of the trim tab servo all wired up with the switch and the position indicator that was supplie with the servo.

And finally back to level position....

Tomorrow I prep the leading edges for primer and then start the rolling process.....

442 hours - Look ma, no more clecoes!

I'll continue to take credit for even small milestones at the rate that I am going with the left elevator and trim tab. I managed to rivet the other half of the trim tab hinge to the top of the elevator, and managed to sink 6 pop rivets into the last riblet ( 3 on each side). Checked the alignment of the hinge pin and it still goes on with relative ease, which means that I did not bend any of the eyelets out of alignment while riveting the hinge on. All the pop rivets went on with relative ease - nice and flush. Then I decided to try to tackle drilling out the one pop rivet on the outboard side of the trim tab that was sitting just a bit too proud for my liking - remember, the one did not want to drill out a couple of days ago.

One thing I have learned about drilling out steel pop rivets - avoid it all costs! Anyway, more on that later. Here is the elevator with trim tab in position  - no more clecoes holding the hinges or the riblet - everything is riveted.

Next is a close up showing the pop rivets now holding the riblet on the elevator (left side of pic), and the gap required between the outboard edges of the elevator and trim tab (3/32")

I'll remove the sharpee marks on everything now that the trim tab installation is all but complete. That way it won't look like my gap line is way off the mark !

Next is a shot of the clean line on the top of the elevator with the trim tab in the neutral position. After all the careful measuring and re-measuring and trial fitting, sure is nice to see this come together. While it has taken me a long time to get to this point, I am still glad that I have only had to make one trim tab, while others that reach this step sometimes have to make two or three before they get it right.

And a nice rivet line of flush rivets attaching both halves of the trim tab hinge to their respective parts....

I used the hand squeezer again with the standard 3 inch yoke, with the small 1/8" x 3/8" wide flat set for the shop head (minimum interference with the hinge eyelets), and the 1/8" x 1/2" wide flat set on the other side - same way I did the hinge on the trim tab. I was still really concerned about not having enough clearance for some of the eyelets, since some of the rivet holes are directly behind an eyelet, but between the thckness of the two 1/8" thick flat sets, plus the gap required between the sets to create the proper shop head, you really don't have to worry about it too much. Just go slow and make certain you do not apply any undo pressure on any of the eyelets and it works out fine.

The hinge pin sticking out of the end is part of the temporary hinge pin they provide in the kit. You get the proper length hinge pin in the fuselage kit for some strange reason. The end of this pin still has to be bent and either safety wired to the E616PP trim tab spar on the elevator, or secured by using an eyelet taken off of a piece of hinge (I will probably do the latter). For now you just use the temprorary one to get it all lined up and installed.

Next is the fiasco with drilling out the pop rivet on the bottom of the trim tab. Truth be told, both of them were sitting a bit proud of the surface, but after all I went through just to drill out one of them, I am totally fine with leaving the other one completely as is. No matter what drill bit I tried to use, I could not get this rivet drilled out to save my life. And the standard method for solid rivets, which is to drill the head out and then snap the head off - Haaaa! Forget that. The rivet already has a hole in it from the mandrel going through the center of the pop rivet, so the edges are already shallow, and this is a hardened structural pop rivet that will not break away like the solid rivets do.

So the things I learned from posts on VAF if you ever have to do this are: take a small diameter punch and drive it lightly with a hammer through the existing hole oin the center of the rivet until the bottom (round part) of the mandrel comes out the other end, then take the drill and drill out the rivet.... simple - right? Not really.

I think I finally reasoned that I needed to use at least a 7/64 inch drill bit to drill out the rivet, because that is what I had to use to widen the original rivet hole for the pop rivet. You pretty much have to drill out this rivet by drilling through the sides without enlargening the hole. I ended up getting the head to lift out of the hole just enough to get a pair of small needle nose pliers on the head, and I tried crimping and twisting the flanges of the head off so I could then punch the remaining part of the rivet out of the hole. It ended up requiring the combination of drilling out the rivet with a larger drill bit (7/64"), and then prying off as much of the rivet head as I could, without damaging the trim tab skin, and drilling some more until I could put a punch in the hole and drive out the remaining portion of the rivet.

I finally got the dang thing out, and much to my surprise did not enlargen the hole too much, but it was still widended enough to cause me some initial concern about setting another pop rivet in the same hole. I decided to go ahead and try it again after trial fitting a new pop rivet in the hole, and I realized that all that work to get the rivet out actually deepened my dimple just enough to allow the rivet head to sit nice and flush in the skin. The rivet grabbed the riblet and the skin pretty much the same way that the first one did, so it turned out to be a nice tight fit. This next pic is the remnants of the pop rivet that I had to drill out. there is the round mandrel tip that had to be punched out, the rivet shaft, and a small piece of the rivet head that I managed to pry off with the needle nose pliers....

Moral: Avoid drilling out pop rivets if at all possible - the structural pop rivets are a pain in the ass to get out.Perhaps if I practice removing them I will get better at it. This whole process brought back very bad memories from working on the horizontal stabilizer and messing up rivet holes, requiring a major structural repair after the fact. Fortunately this experience turned much better than that one.

Next is a close up of the gap between the trim tab and the elevator.

And finally some pics showing the nice streamlined trailing edge one from the outboard side and the other from the inboard side of the elevator - still looks very nice, even after all that mussing and fussing and fiddling with the parts all this time....

440 hours-Elevator riblet prep completed

Sure is fun trying to finish up a major airplane assembly when you are fighting a relapse of strep and endure the largest snowfall in the month of February that Denver has ever had. A 2.5 day storm dumped 20 inches of snow that left 3.5 foot snow drifts on my driveway. Finally had to put the snow blower to work..

Anyway, I managed to summon enought strength to do a little work on the bird tonight. Except for a touch up coat of primer, the riblet and the elevator skin rivet holes were drilled, dimpled, and prepped for the MK319BS pop rivets that will need to be used to attach it to the elevator.

I finally committed to marking and drilling the holes for the riblet. Marked the first hole wigh the center punch at the intersection of the sharpe lines I had drawn that mark the hole locations in the riblet (or so I hoped). I decided to simply work the drill bit by hand without running it with the compressor. It does not take long for the drill bit to penetrate the thin .020 aluminum skin of the elevator. I did it this way to verify that the holes were in fact lining up correctly with the riblet under the skin. Luckily this turned out to be a non-event. All the holes I drilled were pretty much spot on, and the riblet web aligns almost perfectly with the ends of the skin edges of the elevator.

Once the holes were drilled I needed to debure and dimple all of them. This requires 6 rivets - 3 on the top and 3 on the bottom, and uses the existing holes from the original practivce kit rib from which it was fabricated. I was able to use my standard dimple dies and 3 inch yoke in the squeezer to dimple the first hole closest to the spar edge of the elevator, but had to use the close quarter tool to get to the remaining four holes because the opening was not large enought to fit the yoke in side to set the dimples.

Here is one of the leading edge holes dimpled with the squeezer:

Then I had to get creative again. I needed to support the entire elevator in such a way that I could slide the skin over the close quarter dimple tool so I could slam the remaining dimples with the rivet gun. This setup required the use of a 2x4, clamps, and two chairs, one of which was replaced by my son who graciously came out to help me once again. In previous posts at the beginning of the left elevator build I needed to use some 2x4s to dimple several other holes in the skin. I used the same 2x4 adn had to place the close quarter tool on either side of it to provide the necessary clearance for the holes on both sides of the elevator skin. The 2x4 was needed to extend the tool out from the edge of the table far enough to clear the remaining portions of the elevator.

The last shot above shows the tool on one side of the 2x4. When I flipped the elevator over to dimple the holes on the other side I had to move the tool to the other side of the 2x4 to maintain clearance from the rest of the elevator, which tends to get in the way.

Riblet in place after all the holes in both the elevator and the riblet were dimpled:

All riblet holes on one side nicely dimpled.

This last pic is of the riblet after setting all the dimples and repositioning it inside the elevator. The holes need to be final drilled to 7/64" in order to fit the MK319BS pop rivets. Every time I have had to insert and remove the pre-primed riblet after setting the dimples, the primer tends to get scraped away from the riblet where the dimples are located. The parts tends to form a tight fit which locks into place once the dimples align with each other and the part slides into its final resting position. This makes it difficult to remove without marring up the primer a bit. So, I will put a fill coat of primer on this and then slide it into position for the last time, and then set the pop rivets. One step closer....

More snow in the forecast for tomorrow. Just another day in Colorado in the winter time......

Picture catchup time since 1-18-12 - Trim tab and servo mount work

So last post I qrite bout everything I had done. Here are some pics to go with the post:

First shows the NAS 1097 oops rivets I used for the two rivets holding the lowest part of the trim servo mounting brackets. Since the flush head on these rivets is very small, it does not take much to countersink the hole with a deburring bit by hand. Notice one of the rivets already inserted in the hole.

Servo mounting brackets, cover plate, and elevator side of the trim tab hinge ready for primer:

Used some tape to mark the 3 5/8 inches of threaded rod that I needed to cut. Used the dremel cutoff wheel and grinder to smooth the ends. Clamped the rod between two blocks of wood to keep from damaging the threads.Took all of a split second to cut the rod.

And after the rod is trimmed and the other clevis is screwed on:

Next is after the mounting brackets are riveted to the cover plate. Shows the low side of the trim servo and really illustrates quite well the reason why you need to use the oops rivets on the low end so that the botom of the trim servo case will clear the rivets. Even with this setup, I will be curious to see how vibration and flight loads on the control surface impact this clearance. You will know if it is rubbing by checking for marks on the bottom of the servo case where the rivets are touching it. No marks is good,means that the clearance is adequate.

The entire trim servo assembly. The clecoes will be replaced when the time comes. In fact, I am thinking about replacing the screws for this with some torx head screws, because everyone says that the phillips head screws get damaged very easily

:

Next is fitting the inboard riblet. The web is inside so that solid rivets can be used. This process was a major pain the ass because I was trying to use some of the existing holes in the riblets and basically reverse-match drill the trim tab skin. A lot of careful measurements taken here before I started drilling holes. This riblet turned out pretty well.

And here is the riblet that goes into the outboard edge of the elevator. Notice the lines I have drawn through the center of each existing hole in the riblet, and the lines drawn after measuring the hole locations on the skin. Before getting to this step, you need to have already fitted the trim tab to the elevator, drilled all the hinge rivet holes on both sides, and filed down the edges to provide the required 3/32 inch clearance between the edges per the plans. Once you have done all that, you can fit the riblet on the elevator.

Another shot showing the nice side of the trim servo cover plate after the mounting brackets are riveted. You can see the 4 AN426AD3-3.5 rivets in the dimples (large heads) and the two AN1097 oops rivets (small head). Used my hand squeezer for these - just have to make sure you don't ding up the web of each mounting brackets. Trim down your yoke if you need to.

Next is the flat file I used to finish trimming up the edges of the elevator where the trim tab fits on the outboard end. Just had to do a little bit of filing to even up the edges. Everything looks nice and square.

And finally my latest acquisition of tools. Shown are 3 of the four wire strippers from craftsman professional tools, the 25 watt soldering iron, the slim line heat gun, and the box of assorted heat shrink tubing from GB products that I found at HD. I will be soldering a pigtail extension to the trim servo wires. Probably about 8-10 inches worth or more.

Funny - I am not even done with the empennage yet and I am already working on electrical stuff. One of the things you learn as you start to build the remaining structures of the airframe is that you really need to think about the build from the inside-out. This means having an idea about your wire layouts adn requirements, tubing lines, placement for landing, nav, and position lights, antennas, and so on and so on. The more you have this figured out ahead of time, the easier it will be to put everything in place during the framing process. The trim servo wires will need to exit the left elevator and make their way into the fuselage, and some sort of service plug or connector will need to be created so that it can be disconnected and serviced as necessary.

This last pic is of the outboard end of the trim tab, after I had measured, drilled and set the pop rivets for the riblet. UNfortunately the two rivets on the bottom side did not sit down very well in the dimples, so I tried to drill one of them out. I thought this would be easy, having drilled out other pop rivets on the rudder LE. Boy was I in for a surprise. I guess those pop rivets are not necessarily considered  to be structural, and so they are made of aluminum. The MK319 BS flush rivets are apparently much harder than aluminum, and even harder to drill out. I have never seen a drill use up two full tanks of air turning a drill bit and seeing absolutely nothing get drilled out before. Very wierd, and very troubling at the same time, since I don't know how the hell I am going to get this rivet out of the hole.

Anyway, I found some info on VAF about this. Looks like I need to punch out the remaining mandell head and then I am supposed to be able to drill the rivet out. We'll see houw that goes. Sure don't want to screw up the trim tab at this point, so I will take it slow and easy.

Big time snow expected here overnight and tomorrow. We'll see how much more I can get done over the weekend.....