Sunday, December 24, 2017

The End is Near

The end is near, both of 2017 and this wing build.

The ailerons are finished, and I am quite happy with the results. One aileron trailing edge is dead straight, the second took a little work to get out a very minor ripple; I think the ripple was caused by not riveting the trailing edge together as soon as the pro-seal was dry and letting the trailing edge sit unclamped for a few days. No worries should be fine.

I think the secret to building ailerons with no twist is the leading edge straightness. I spent a little extra time making sure the bottom skin was absolutely flat from the stainless steel leading edge weight to the spar. Since drilling the leading edge is very difficult due to the super hard stainless steel, I ended up having some extra "lightening" holes in the stainless steel bar. During final assembly, I made sure the leading edge ribs sat flat on my super flat surface plate (kitchen granite counter top). Once the leading edge is riveted to the spar, the aileron becomes enormously stiff. I am glad I took the extra time to make this part perfect.
For the trailing edge drilling, I make a simple metal guide; should have done this long ago.





I am currently working on the flaps and planning out the internal stuff the needs to go in before the bottom skins are on. I am thinking I will fully install the heated AoA pitot tube, and the autopilot servo for the future G3x panel. I am planning the magnetometer for the right wing tip and the VOR antenna for the left. So my present plan is to not pull any wires for those until the tips go on in a year or two. The wings already have conduit for the wiring, so pulling the wires should be easy.
As for the lights, I saw some new Baja Design that seem choice, but with the pace of technology, still not sure if I will install now.

Friday, November 17, 2017

Progress too

Making steady progress on the wings. Everything pretty much to plan. One note: the instructions were written long before the extra aileron brace was engineered. So the instructions say to install the aileron brackets before the flap brackets. This build order needs to flip around now. The flap brackets need to be installed prior to the aileron brackets since the extra reinforcing  interferes with the rivets as seen in the picture below.
 One thing to note, the bottom skin rivets can still be accessed with this brace in place; on the RV7, I believe the brace interferes with the skin rivets, not a problem on this RV9.

Moving on now with the flaps and ailerons.....

Friday, September 22, 2017

Wing Skins


 Look no clecos! A few of the rear spar rivets are still not in near the root; it seems these will be easier to squeeze once the wings are out of the build stands.

The easiest way I found to do this was from the trailing edge. Starting with the center rib of each skin, I would rivet the skin to the rear spar between the two center ribs. Then work up from the trailing edge on each rib. I could just reach the fourth rivet above the J stringer by laying on a creeper. 


After each skin was done on the lower portion, I would then corral a helper and rivet each rib the rest of the way up and then the main spar. I found a helper with a tungsten bucking bar was the easiest. I also used a wi fi endoscope camera hooked to my iPad so I could see around the other side and validate each rivet as we went. For $40 on amazon, the endoscope camera was well worth it. After a while, my friend would understand a good rivet and we would move along.


I took advantage of my rivet buddy not wanting to go home (because of traffic, not the wife, so he said) and was able to get all the top rivets on the right wing too. The rest I can get from the bottom with a creeper.

The wing is going slower than I anticipated, but I am taking my time and keeping the quality up.
After checking the twist, everything is as before. I did notice the right skin had to be cleco'd in a certain order to get all the holes to line up, so I ended up clecoing the skins on twice and using a cleco in every hole. There must have been some sag the first time. I am glad I didn't start riveting until both skins were on and fully cleco'd in place.

Sunday, September 3, 2017

Small Steps are Still Progress

As the wing build continues, no real drama. The leading edges went on without much trouble; not nearly with the difficulty I envisioned from reading other blogs. As it turned out, most of the leading edge to spar rivets were reachable with the squeezer. I only had to drive about 10% of them, and of those only 5 on the right wing were blind and needed two people.

For the split strip between the tank and the outer leading edge skin, I tweaked the nut plates to better conform to the skin using a vise and some scrap brackets. This worked out well.

After installing the tanks, I noticed the skin thicknesses aren't all the same. Some are 25 mils , others are 32 mils. I wish I would have beveled the skins before assembly to make this transition smoother, but maybe there will be a chance to smooth the 7 mil step before paint.

I started riveting the skins on with my resident engineer-in-training. I am still trying to work out the best technique. I tried the long offset back rivet tool, but this takes so much umph on the gun the rivet heads aren't pretty; acceptable, but not pretty. So we tried the normal method as in the picture. This worked out well for the ribs, but still looking for a better method for the skin to spar rivets.


Saturday, July 29, 2017

One line One month

I was trying to get at least one page of instructions done per month.
Got the fuel tanks done in two months and that was about two pages of instructions.
Than I ran into the next step:" Deburr, Dimple (prime) main skins"
Really simple sentence, but took me a month.:-)






But this is summer and I am  distracted. Here is my typical view during my Saturday morning runs.
Hard to get into build during the beautiful summer days. But I am making progress, skins are done and am working on countersinking the spar to accept the skins.

I never installed the flush rivets for the ribs that go under the tank skins, so am doing that now. I wish I would have done this when the ribs were riveted to the spars, and before the skins were matched drilled. So now I have to c-sink the ribs holes under the tank to flush, and the ones for the skin to 0.007" deeper per the plans. I will probably squeeze these rivets right after I dab primer on all the spar c-sink holes; this primer may not be required, but I am going to do it anyway, at least for the main spar.
Working on stall warning now. And hope to get the top main skins on before the end of August; although the beach looks mighty inviting.......

Friday, June 30, 2017

Fuel Tanks- Breath didnt Hold

Last report, I was holding my breath the fuel tanks would not leak.

Like all good learning experiences, my tanks leaked; both of them, mainly from the rear seam.

The one tank leaked from the seam near the fuel sender and access hole. This was easy enough to fix by removing the access panel and adding more goop. 

The tank in the picture leaked from the top seam near the middle, in 2 places. Ugh.

There were many options I found on-line to fix this:
1) use Loctite adhesive designed for just such a repair.
2) ignore it and hope it goes away.
3) cut a hole in the baffle, add more sealant and then use a new access plate to cover over hole.
4) use the really thin Proseal that is brushable, pour it in the tank and slosh it along the seam.
5) make a funky applicator with a syringe and tubing; using a USB camera, and add some more Proseal to the seam thru the filler neck or the sender access panel.

Of course, being the expert builder that I am, I did none of the above.

I decided to use option 6), which is not listed above. If that didn't work, use option 3.

Option 6) was to drill out the baffle rivets in the offending area, wrap a towel around the vacuum cleaner nozzle and tape it to the fuel filler spout. With the manometer hooked up, turn on the suction and leave the fuel sender screws out to avoid over pressurizing the tank (wouldn't this be under pressurizing?). Add some Proseal to the seam, and gently open the seam up by gently flexing the tank skin. To my surprise, the sealant sucked itself into the gap. I used a heat gun to gently heat the tank skin to help the Proseal flow into the cracks. The whole time the tank was under 27" of vacuum.

After resetting the rivets, I let the tank sit for a day. I started the pressure test tonight, and the leak check using soap bubbles showed no leakage. Normally I would say done, but I plan to let it sit over night just to make sure.


Sunday, June 25, 2017

Fuel tanks: Stop the madness, I am tired of learning

Fuel tanks are done, Yippee Ki Ya!

This last week has been fun learning how to play with ProSeal. The baffles and support brackets went on without much trouble.

For those of you building a RV9, it is important to note that the baffle doesn't naturally want to sit properly. The top and bottom skins are designed to not sit perpendicular to the back of the baffle.  So when the baffle is dropped in, it has to be forced to align with the internal ribs. Once the baffle was set down on the ribs, I pushed the baffle into alignment and pressed in a  -4 rivet thru the baffle into the ribs. This kept the baffle lined up while I inserted the gazillion silver clecos for the top and bottom row of -3 rivets, and clecos for the rest of -4 rivets for the baffle to ribs, without the brackets.

For the -3 clecos. I pushed in a -3 rivet every 10th hole to line up the skin and baffle before clecoing. Once all the clecos were inserted, I gently squeezed between each -3 rivet location with a Vise Grip welding pliers to squeeze out any excess Proseal.

I started riveting the -3's at the middle of the tank. I found I had to take the countersink (with a countersink stop) and touch up each hole before inserting the rivet; otherwise the heads were not always flush to the skin.

For the baffle to rib to bracket rivets, the pop rivets went in smoothly. I made sure I set the -3 and -4 rivets in one seating so the Proseal didn't have a chance to harden.

The sender, pickup and drain went in as per plans.

I am now in the waiting period when I am ignorant and happy, thinking the tanks are done and won't leak. Here is my leak check setup using the manometer method. I am expecting I can blow in the tubes enough to pressurize them to 27" of water. I am holding my breath hoping they won't leak.

Sunday, June 18, 2017

Fuel Tanks-Part 2

Tank assembly begins! 
The bottom stiffeners were installed as per plans. I mixed up 1 gram of Proseal per linear inch and this was just about right, taking into account losses from leaving stuff on the mixing plate, smeared on the ceiling, etc. Did I mention this stuff gets everywhere?

I decided to use the "faying surface sealing method". The next day, I mixed up another batch of Proseal per the instructions, and using the baggy technique, applied it to the ribs. I then cleco'd the ribs to the bottom skin using a cleco in every hole.


In the same session, I mixed a second batch and applied Proseal to the top of the ribs, inserted the tank into the frame and cleco'd the top of the skin to the ribs again using a cleco in every hole. Then I smoothed the excess bleed out with the tip of the plastic knife, and let it set overnight. I added tape to keep the skins from spreading due to the Proseal's viscosity.






The next day, I came back and removed every cleco four at a time, and used the #40 (-3) countersink to clean up the dimples. This removed the excess squeeze out and removed a sliver of aluminum to provide virgin material for the rivet to seal against.



I did not use "tank dies" because I don't believe in them. Tank dies are special dies only that set the rivet a few thousandths deeper. The theory being this allows the rivets to sit flush with a thin layer of Proseal in between the rivets and the skin. I think this is nonsense. Using normal dimple dies, the Proseal squeezed out during riveting and all that remained was what was needed to fill in the voids; I don't see a reason why there needs to be a thicker film of Proseal between the rivet and skin. Just my opinion.

Update-A factory  engineer wrote the following reply: I also have some concerns about the use of tank dimple dies, but in my opinion, by installing the ribs and then waiting to rivet, you just moved the thick build-up of sealant from between the rivet and skin, to between the skin and the rib.
The squeeze force of a cleco is much lower than what is exerted when setting a rivet.
The sealant is very viscous and doesn't easily squeeze out from between the rib and skin.
I am pretty sure that just installing clecos and then letting the sealant cure before riveting leaves a much thicker layer of sealant between the rib and the skin. Far less desirable than the result attained if riveted wet, in my opinion.

Comment: I still prefer the Fay sealing method I used and described above. I am afraid by wet installing the rivets, the skin may pucker between the rivets; there is heavy force on the rivets and no force between the skins when wet riveting, in my opinion.

The riveting went fine. I had to drill out a few clinchers, because the Proseal makes everything slippery. Also, if I didn't press the rivet down in the hole and squeeze out the excess, I would invariably get a rivet sitting proud. I used a hemostat to place the rivet in the hole filled with Proseal, pushing lightly to squeeze out the excess goop. Then I cleaned off the outside with a acetone-damped rag, cleaned the mushroom set, and riveted. I found using lower air pressure and feathering the trigger helped set the rivets without clinching. With 30 grams mixed, I was able to set 3 rows on the bottom,  coat the shop heads, and fillet the three ribs, before the stuff started getting hard. It took me three nights over a week to get each skin on. With this fay sealing method, there was not a rush to set all the rivets in one session; I felt this made for much better results because I wasn't stressed trying to rivet everything before the Proseal set up.

The tanks skins and ribs are all riveted now. Looking back, I don't know why I was so apprehensive, but it was a learning experience. As a side note, I used MEK to clean the faying surfaces, but switched to acetone to remove the excess Proseal to try and preserve my MEK for more important tasks; I can no longer buy MEK locally.

Monday, May 29, 2017

Fuel Tanks

I have been working on the fuel tanks. The Pro-seal is about to expire, so have been a mad man trying to get the tanks together.
Everything went per plans, but did some things that made it easier. Since I am doing both wings at the same time, the tooling and jigs get setup and taken down only once, so things go quick.
I made a template and verified the tank leading edge shape matched the outboard leading edge. The left wing I nailed perfectly, but the right I had to disassembly the ribs and tweak slightly. I also made the end ribs of the tank fit the curve of the skin as near perfect as possible to minimize the gap the Pro-seal has to fill in.





















For the tank brackets I made a wood jig to hold the brackets and get the middle hole centered. Of course, all the brackets came from the factory exactly same length, except for two.Oh well.

The brackets are installed on the baffle and the line centered in the baffle holes. Then the remaining holes are drilled using the baffle as the drill guide. I found out that the baffle is not symmetrical; there is a top and bottom. In addition, the baffle flange orientation is mirrored on the right, but not shown explicitly on the plans, leading to additional confusion. You are warned.
After the brackets are drilled to the baffle they are installed on the tank, and the tank is installed on the wing for match drilling to the spar. There were several gotchas:
1) The baffle has a top and bottom, the prepunched holes are not symmetrical top to bottom.
2) The distance from the baffle to the spar is too close for clecos near the root. If I tried to use clecos to hold the tank skin to the baffle, the baffle and wing tank did not sit on the wing properly.
3) others have dimpled the baffle rivet holes; I don't see how this would work on the RV9 since there is not enough clearance; I think the baffle rivet holes need to be countersunk per the plans.

After the brackets are match drilled to the spar, the riv-nuts are installed. I used a bolt and nut to drill the brackets for the rivets as in the pic. (The hole in the wood is for the nut to rest in.)





The rest went as per plans, nothing special. Prior to priming, I edge rolled the seams very slightly using my thumb technique. Not sure if this is needed, but I do not want any of the skins lifting off the spar and I could not find anyone on line who regretted doing this.
Lastly, I primed in prep for final assembly. The plans say only the bracket needs to be primed, but my minimum amount to mix easily is 50 ml.  Not wanting to waste any, I primed the outside of the skins where they will rest on the spar and splice plate, and I primed the outside of the two end ribs, and the backside of the baffle. I am thinking the tanks may sweat when full of fuel, so I figure it wouldn't hurt to prime the outside that is exposed.

With all this work, I think I am ready for final assembly of the tanks. Hope I have enough clecos ;-)


Tuesday, May 2, 2017

Harvesting Clecos for Wings

So have started building the wings. Not much to write about as everything started out well and went as per plans. Of course as I was saying this to myself I did find some "knowledge" was needed, and a few bandages. But I am getting ahead of myself.

Here is the bountiful harvest of clecos.  And a warning. Just go ahead and order a thousand 3/32 clecos; if ordered all at once, there is a break in the price at a thousand, and the shipping is only one time. I am on my fourth cleco order; UPS is making bucks on shipping. Here is my cleco farm, ready for harvest. I am doing both wings at the same time, so this is only one of the two wings, Yes I ran out of clecos; the rest are coming in time for the tanks. Total cleco count will be slightly more than a thousand.
The main skins went on as per plans, no really drama, except I had a few holes in the rear spar where the holes in the rib, spar and skin didn't line up. Next time I need to make sure the rib holes line up with the rear spar during the rib to rear spar riveting. It is kind of tough to do it after the rib to spar rivets are in.

I didn't quite follow the plans when I put the J stringers in. I indeed drilled through my finger, even though the plans say  "be careful don't drill through your finger"

The leading edge ribs are notoriously for being hard to fit into the skin. After reading many blogs of those who came before, I decided to reshape the leading edge ribs.  During my first attempt, when the virgin ribs were inserted into the leading edge skin, the rib flanges were actually warping from straight in order to fit the leading edge radius of the pre bent skin. This is ugly, and causes scratches and bumps on the leading edge of the skin. When compared to the fiberglass tip, I think the pre-bent skins have a  different leading edge shape causing a poor fit.  After reading many blogs of those who came before, I decided to reshape the leading edge ribs. Here is a picture of the virgin rib fitting onto the skin. Notice how the tabs in front of the prepunched hole are holding the skin away.


 Everything fits much better with a small tweak to the flange. I am being careful to make the left and right wings the same, since this portion of the wing contributes to the flying qualities. Here is a picture of the reworked rib installed on the left leading edge. There is still a gap between the rib and the leading edge. I don't think it hurts anything, but I might throw some extra Proseal in there when I do the tanks.
I also had an interference on one of the rib to the spar rivets. This is the rib closest to the tank. Not hard to take care of. I am continuing on and looking forward to the Proseal Challenge.






Thursday, April 6, 2017

head...shoulders..ribs and spars

Much work has been accomplished.
I drilled out the fuel tank ribs for better venting during fueling. I used a Forstner bit so that I could get close to the rib flange. And I enlarged the wire routing holes as per the previous blog post using a home made jig to center punch all the ribs in the same location and a step drill . Easy Peasy.


The main ribs were primed with no drama. Wings stands were bolted to the floor (shhhh don't tell mom). I am building both wings at the same time so it goes pretty quick; once the tooling is set up for the left wing, it is a breeze to finish the task for the right wing. I flipped the wings up right to rivet the main ribs to the spars. This provided good access. My son was home from college on spring break, so we were able to do 1 and 3/4 wings in a few hours. I used a double offset on the gun and this seemed to really suck up the driving power. I had to crank up the pressure to 60 psi and crank up the flow. This was manageable with two of us, but the bar was bucking quite a bit. Could not have done it without a tungsten bar; that compact extra mass really help make up for the double offset power suck up.

I had to drill out two rivets just because; I should have drilled out only one... the second was best before I touched it :-(
To rivet the remaining five ribs, I  got creative and made some simple tooling. I used a sheet of hobby plywood from the aviation isle of Hobby Shack with the thickness chosen to match the no go rivet gauge. This allowed me to hold the bar on the underside and not have to worry about scratching the spar or setting the rivet too thin. I also taped the double offset to the gun so it wouldn't rotate. I used two layers of duct tape on the end to try and help prevent smileys on the rib. In addition, I used one finger around the rib and operated the trigger with my middle finger. This kept me from tilting the gun over inadvertently as I watched the bucking bar dance around. Each rivet seem to take forever to set. I was concerned about work hardening the rivets, but no problem. I also did not assembly all the last ribs at once, but rather as I went. This allowed much better access to the rivets.
I still need to squeeze the rear spar rivets, but expect no drama with that. Onward.

Saturday, March 18, 2017

Wings- Ribs


These are my wing ribs all deburred.

The two yellow spools are the sandpaper I used for deburring the holes and flange edges. I also used just a loose sheet of 220 grit pinched between my fingers for the long straight flanges. The abrasive spools were a 1/16" rope and a 1/4" flat ribbon. This worked really well. I probably used 25% of a 25 foot roll. Many of the rib flanges were fairly well deburred already, so it didn't take much more for me to be satisfied. The lightening holes needed the most effort.

I also built the rib flange forming thing-a-ma-gig sitting on the table. It forms the flanges to the perfect 90 degrees to the rib web. It works very well. However, when I tried it out, I grabbed a nose rib and looked at the flange. It measured almost perfect without me having to touch it. Then I looked at the center rib, seems perfect too. Did I spend half a day and $20 on this thing for nothing? I will finish up checking the flange angles tonight. But I will probably be too embarrassed to tell anyone how useful, or useless, this tool was. It is well worth the effort to construct for the flanges on the tail ribs, wish I had it then. But I hope I never have to  rebuild the tail feathers.

Also in the picture are the mods I plan to make to the ribs. I talked to Van's Aircraft support on Friday and they said what I had planned seemed reasonable. If you wish to follow my example, please check with Van's yourself. So here is my plan: for the nose rib, I will enlarge the internal fuel vent hole from 1/4" to 1/2". (This is not the hole the vent tube goes thru, but the one that will be at the high point when filling the tanks.) The stock hole seems really small to me, and others have complained the tanks are slow to fill. I don't plan on doing aerobatics, nor uncoordinated flight (who does?), so I am not worried if these enlarged holes cause the fuel to slosh around a little more. For the main rib, I plan to follow the supplemental instructions on the Van's Aircraft site and add a hole in the main web to the right of the first lightening hole in the picture. This will be 3/4" per the supplemental instructions. Also the RV9 plans say it is permissible to enlarge the forward tooling hole to 1/2". But the same Van's supplement says the RV7 and 8 can enlarge this to 5/8". I will follow the 9 plans and only enlarge to 1/2 ".

Lastly in the picture, behind the table, are the wings stands for the spars. I plan to build both wings at once. These stands are a God send. Thank you to the builder Billy who provided them.

So that is my plan. Onward and upward, (well not yet anyway) :-(

2018 Update: The extra hole in the  rid I added for the conduit was positioned too low and right over a rivet. this made riveting the skins tough. I think it it was up 3/8" to 1/2 " higher, riveting the skins would have been much easier.

Sunday, March 5, 2017

Starting wings-spars

After having mastered the tail section, now it is time to start taking bigger bites. Goal is to have the wings done by August for a late summer trip to Vans to pick up the fuselage kit. At least this is what I am telling people. The real goal is to have the garage cleaned out enough to get the fuselage kit inside by August.

The wing spars went together fine, but there are some minor things to be aware of. I had to look at a few other builders website and a few pictures of their spars to figure out the plans.(Thank you, thank you, and thank you)

First thing is the inboard spar doubler gets several countersunk holes. 3 of these are for the gap fairing that will have another thin sheet between the countersunk hole and the rivet. Therefore these 3 have to be set 0.007" deeper to allow for the skin. The other countersunk holes just see the rivet so these are set flush. Now there are regular rivets up near the top web. These are called out as standard rivets, but they are very close to the rivets that will be used for the skin attach and am not sure if I can bet a bucking bar on these. I am wondering if these should be flush rivets instead. I followed the plans, because I don't know what I don't know, but I did put the manufactured head on the outside so I could drill it out if I have to switch rivet styles later. Here is a pick of the root doubler and the rivets.


 The tip was fairly straight forward except the plans do not call out leaving out the rivets for the aileron bracket. So only the inboard six holes got rivets right now. Seems this is the same as the root doubler, only 6 rivets installed at this stage.
After these steps were done, it doesn't seem like much was accomplished, but this was a full page, so it is a good start on the wings. Now to deburr and straighten the ribs. And get the wings build jigs bolted to the garage floor.

Thursday, February 9, 2017

Tail complete, less tips

Yahooooo!
Tail is complete less tips.
The elevators were assembled onto the horizontal stabilizer with no issues. Remember the horizontal stabilizer  is the first thing to be built. It is sure obvious to me that building the tail feathers taught me a lot about building. I am glad I started with the tail as per Van's recommendations. There is definitely a learning curve to this. here is a shot of the completed tail, taken from far enough away to hide my lessons learned. No seriously, the elevator was inspected by a tech counselor, so no worries, all is good. But it is going to be a painted airplane, no polished aluminum for me.

The elevator attach was easy. Everything was square and true. I only had to screw in one heim joint 1/2 turn to make both sides even within 0.010". It is quite amazing how close everything lined up. What an amazing kit.
Now to find a place to store it. And start the wings.

Lessons Learned:
1) Use proseal on the trialing edges. I use the T88 epoxy on the elevators to try and keep the skins from separating. All this did was make a mess to clean up; the epoxy squeezed out and cured onto the outer surface of the aluminum skins, and was a bear to clean off. The proseal clean up was much easier.
2) Instead, use the wood block that was built during the practice kits to break the skin's edge to prevent the edges from separating during the trailing edge gluing/riveting.
3) For the trailing edge rivets, don't use the back rivet set for the final setting of the rivets, it is better to use the rivet set with a hole in it and a the 1/4" diameter flat rivet die used for squeezing the -3 rivets. The reason is the back rivet set is slightly concave, whereas the flush set is flat with rounded edges.
4) The use of a double offset -4 set for the tip ribs to spar is a necessity. This lesson cost me a new tip rib.
5) Without a tungsten bucking bar, the skin to elevator spar rivets would have been nearly impossible. The extra mass and small size is really needed.

Finishing Elevator

The left elevator was finished as expected with no issues, except for some reason, the elevator skin to the rear spar had a gap once everything was assembled; probably no more than 0.002", so most likely within spec without being touched. So as I riveted the spar to skin to hinge, I would use the squeezer to re dimple the whole structure, then set the rivet, then move on to the next hole. This was more annoying than anything else.
Moving on to final elevator assembly.

Sunday, January 22, 2017

Elevator Trim Tab

Today was a rainy day in Los Angeles; perfect day to be building. I knew it was going to rain, because the original internet (the sky) sent two bits of data yesterday from Santa Barbara saying it would be so. Here is a picture of the data; or maybe this was the dashed line you see on the weather maps.



So the elevator trim tab went well but I did not follow the directions verbatim. They say this is the part that everyone has trouble with, and if I had followed the directions exactly as written, I would have had trouble too. But planning this out yesterday, while the internet data was being received, I decide that there was a better way.

I followed the plans as written up until the trim tab horn is dimpled. I chose to dimple and rivet the trim tab horn after the ends were bent over. But let me walk through the order I did things.

I matched drilled the holes and deburred per the plans, but did not dimple any holes yet. I bent the trailing edge to the correct angle as per the plans using a 4 foot section of  2x 4 and some el cheapo hinges from the aviation aisle of Lowe's, as per the plans.

Then I built the bending blocks for the ends as per the plans.I practiced on some scrap aluminum until I felt comfortable working on the expensive stuff. I left the blue plastic on and used double sided tape to keep the blocks from moving as I dressed the ends.  This didn't work completely as planned, as the trailing edge in the forming blocks still moved a little as I bent over the ends; but still came out acceptable. I used a piece of 1" x 2" wood to start the bend. Then I used the flush rivet set in the rivet gun and really gently smashed over the edge till 90 degrees. I had previously filed in a 1/16" radius in the bending block to form a nice radius in the finished bend. I worked the gun back and forth until the bend radius was even without smashing it completely.



The skin area for the trim tab horn was not dimpled or riveted earlier (as the plans would have had you do) because then the trim tab wouldn't sit nicely in the forming blocks. So now I went back and dimpled the trim tab holes.It is interesting to note the #40 holes in the spar and the skin seemed to already be punched to final size, but I went back and reamed them anyway to clean up the holes.

Then I riveted the trim tab horn to the skin, except for the trim tab to spar holes, per plans. There is a spare to skin hole outside of the trim tab that I didn't dimple before the trim tab horn was riveted on. So I had to dimple this after the trim tab horn was on. This presented a problem in that there was no enough room next to the horn for the dimple die to sit down properly. I ended up drilling a hole in some scrap aluminum the same thickness as the trim tam horn and dimpled these two sheets at the same time In the picture below you can see the hole and the scrap sheet. Next time, I will dimple this hole before the horn is riveted on. I also bonded the two halves of the trim tab together, using JB Weld, to keep the moisture from wicking in between and possible causing corrosion.









Next I deburred and dimpled the #30 holes in the ends. These get pop rivets later.

When riveting the spar to the lower trim tab skin, the tungsten bucking bar is essential. I don't feel this can be done without a tungsten bar because the normal bars are just too big.

Everything else that followed, was done per the plans. nothing special.

I should be seeing the replacement parts for the elevator tip rib in a few days, so I will be finishing that up.

Saturday, January 21, 2017

Elevator, Left Side

The left side elevator started out much smoother than the right. I was able to get the stiffeners back riveted no sweet by using the same method as the right elevator. Here is a picture of how I did it. The plans says to use rivet tape and tape all the rivets in place. I don't like that. My general rule is to have the pieces tight together before riveting. So, I used a completely different method since I know more than the guys at the factory who have built 20 more years of airplanes than me.:-)

So my method uses a cleco in the hole adjacent to the one I am riveting. The rivet plate is taped to the bench and cardboard is used to hold the assembly up off the table. The cardboard has a cut out for the clecos that hold the stiffener to the skin. I start at the trailing edge and insert a rivet one at a time, back rivet and then advance to the next hole. Since I am not using tape against the rivet, the rivet gets marred by the vibration of the rivet gun; but I am painting, so I don't care. The clecos keeps the skin straight as I flex and contort it to get the gun on the rivets.

The spar went well but I learned from the right side and made all the bottom rivets the pull type (with the larger dash 4 hole size) I guess if I really wanted to, I could  squeeze dash 4 solid rivets in the holes I could get too, but that seems like over kill.

But again, riveting  on the tip gave me trouble. More so than the previous elevator tip. The new parts will be here this week. We don't need to discuss this further, but lets just say, the new tools (1/8" double offset rivet set) will also be here this week. And another lessons learned, make sure the bucking bar is on the rivet and not sitting on a cleco holding the skins together. Last lessons learned, take pictures of riveting setups. Part of this trouble came about because I forgot the exact setup I had used successfully on the right side for the same rivets. Moving on...

I have started to work the elevator trim tab. It is not as bad as others make it out to be... yet. But it seems many before me have had trouble bending the skin tabs down. Knowing this, I will probably make up so samples and perfect my technique before doing the flight parts. Now I am off to cut the grass, paint the house, loose weight, before I start building again.... OK maybe just cut the grass... Naw, lets get building!

Sunday, January 1, 2017

Elevator, Right Side

The right elevator is coming along but I had trouble getting to the two rivets shown in the picture below that are back in the gap at the top left of the blue-covered skin. Turns out I was assembling the tip rib incorrectly; the tip skin goes underneath the main skin, I had the main skin underneath the tip skin. By doing it the right way, the main skin can be opened up, providing good access to these rivets. When I followed the directions, it was easy.



On the bottom skin, when attaching it to the spar, the instructions said I could use either all pop rivets or a mix of pop rivets and the much stronger squeezed rivets. I chose to use a mix of pop and squeezed rivets. This made it much harder. I think if I were to build another elevator, I would just use all pulled rivets for the bottom skin to spar; much easier and less grief than having a combo of the two.

For bonding the trailing edge, I used the T88 epoxy instead of the tank sealant. The T88 is mentioned on the plans as an alternate material. I hoped it will provide less pillowing and better bond on the trailing edge than what I had on the rudder. But I have a feeling the pillowing and bonding is due to the metal being riveted so close to the edge, not the bond material. OK I give, the main reason I used the epoxy is because it is a 1 to 1 mix, whereas the tank sealant is a 4.5 to 1 mix. I didn't have a good enough scale to weigh out the sealant and I didn't want to wait three days for Amazon to bring me one. Previously on the rudder, when I mixed the tank sealant, I discovered my Target scale did not read fractions of a gram, so I guessed the mix ratios and luckily got it right.

In summary the right elevator took quite a bit longer than the rudder; mostly because there are many more rivets and the lessons learned on the rudder provided a bit of education and familiarity.

Once the epoxy dried, I riveted the trailing edge per the instructions. This went much better than the rudder, but still had the same seperation of the skin very slightly from the AEX tapered strip. I eliminated puckering between the rivets by gently squeezing out the epoxy with a seaming pliers. I think the only way to keep the skin tight tot the trailing edge is to use some structural adhesive, like JB weld, or to edge break the trailing edge before dimpling. I will try the edge break method on the left training edge.Edge breaking puts a slight crease in the skin edge so it sits tight to the AEX tapered piece. This is described in the plans.

Overall I am happy with the right elevator. I think I could do a perfect job on the left now with this experience. (Right !!! wishful thinking see next post.)