Wings 66.5, Total 529.5 - Initial Rear Spar riveting is done!

I started and finished the right rear spar rivets tonight. Took about an hour and a half and went pretty much without a hitch. Second time around always goes a bit faster.

Here is s series of shots of the rivets:

I disassembled the 4 aileron belcrank brackets from the main wing spar and stored them away until the time comes to install the belcrank assembly. Some people get worried about the integrity of the grip of the nut plates if you screw and unscrew bolts in and out of the nut plates a couple of times. The acid test for this is to determine if you are able to hand turn the bolt or screw as it goes inside the threads of the nut plate. If you can, then the bolt or nut plate may need to be replaced. In my case there was no way that I could hand turn any of the bolts while the threads were still inside the nut plate, so no problems there. The bolts, on the other hand, do appear a bit worse for wear, so I will most likley replace them with fresh ones when the time comes to mount them permenently.

Next is a pic of the stack of ribs that will require quite a bit of prep work - edge deburring, fluting, flange straightening, scuffing, cleaning, and finally priming. Same stuff, just on bigger parts. I will be working on this over the weekend. This takes most folks at least a week or two to get all of them done for both wings.

I managed to get both the main and rear spars stored on my shelves along with both elevators. I stacked the main spars using wood spacers in between. Seems to be working out OK.

Story is always the same when it comes to riveting. It takes hours and hours of prep work, followed by maybe an hour or two of actual riveting to mash everything together. SO far I think that the rest of the wing work will go rather quickly - until I get to the fuel tanks anyway.

Wings 65, Total 528 Riveting tie downs and rear spars

Finally got to start pounding some rivets over the holiday weekend and tonight. Also hosted a small party of fellow RV builders and flyers whom I have befriended over the past few years. It was a really fun party with a movie night to cap off the evening. I showed the movie 6 days and 7 nights from a projector and bed sheet movie screen I rigged up in the garage. This setup worked really well, and I can't wait till I do it again. If it wasn't for hurricane force winds throughout the day it would have been perfect.

With everything primed, it was now time to start riveting parts. I started with the spacers for the tie down brackets. They are riveted to the back side of each tie down bracket, and the shop heads of the rivets hold the nut plate that will secure the mounting bolt for the aileron belcrank brackets.

After trying to squeeze the frist set of spacers by holding everything in my hand like an idiot, and having one rivet end up displacing one side of one nut plate just a bit, I wised up and secured everything in the vise as follows:

Here is the nut plate that got botched up. For now I am leaving it as is, but I may drill it out and replace the whole nut plate. I wanted to see if the bolt would still seat properly in the threads of the nut plate after the tie down bracket was bolted to the spar. It did cause some problems, but the threads finally grabbed the nut plate and I was able to secure the bolt.

It was stupid to try to squuze these rivets without properly securing the work, and this is the result. Sometimes I just never learn I guess. These rivets are long - AN426AD3-7s, and they are a pain to drill out. I had to do it three times, adn will probably need to do it two more times to replace and realign this nut plate properly.

And here it is mounted to the front of the spar:

And here is what the other side looks like before it is mounted to the wing spar:

The right side bracket turned out much better. Amazing what happens when you properly secure the work.

Now for the execution of another hard lesson that I learned long ago. I needed to drill out the bolt holes for all four aileron belcrank mounting brackets. It starts with a number 13 drill bit, followed by a number 12 reamer for AN3 bolts.

Here is a pic of the front side of the spar with everything mounted and bolted into position:

and the back side where the aileron belcrank brackets are mounted:

In order to properly torque all of the mounting bolts, I needed to obtain a 1/4 inch extenstio so that the torque wrench could clear the flanges of the wing spar. I also purchased a reversable 3/8 inch adn 1/4 inch adapter - all from Sears.

One note about the aileron belcrank mounting brackets - Thank you Dan Checkoway for pointing this out. IF you bolt them to the spar, there is no way to insert the long bolt that secures the belcrank to the mounting brackets.It will not clear the flanges of the wing spar. So the only way to mount the aileron belcranks to the mounting brackets is to remove the mounting brackets from the spar, install the bolt and belcrank losely in between the mounting brackets, and then re-install the mounting bracket/belcrank assembly to the spar. I wanted to verify the fit of the bolts to the nut plates, so I went ahead and mounted the brackets to the spar anyway, but I will need to remove them to install the belcrank when the time comes.

Now on to the rear spar riveting - Yipppie! I managed to get all the rivets slammed for the left rear spar tonight, and plan on riveting the right rear spar tomorrow. It took a couple of hours for me to get everything clampled and secured and riveted, but it was methodical, and my clamping process seemed to work out great. Here is the entire assembly ready for riveting on the benches. I secured oine end in the vice in between two pieces of wood, and the other end was angled downward until it touched the work bench. I used my 4x4 clamping blocks to secure the remaining parts of the spar as shown.

I had to get a bit creative about the clamping process. Here are a couple of pics that show how I did it. Clearing the z bend flanges in the sapr was a bit of a challenge, but I devised a way to do this that actually worked quie well.

For riveting, I found that using masking tape on the tip of the rivet set helps prevent smilies and other dings. I take a piece of tape dn lay it over the rivet set, then use rivet to form the dpression in the top of the AN470 rivet set, and then trim away the excess tape with an Xacto knife. The tape will last for several rivets, and then you need to unplug the air from the rivet gun, adn place a new piece of tape on the rivet set again. It really helps keep the rivet heads and skins from being damaged. As you get better with the riveting technique you don't need to rely on it as much, but every once in a while you get a surprise rivet that causes some problems, so you just never know....

The rivet call outs for the aileron support brackets on the rear spar can be a bit confusing, so you need to study the plans carefully to fully understand which holes should be riveted now, and which holes need to reamin open until the other parts such as ribs and gap seals and hinge brackets are added later in during the build of the wings. Each support bracket is a bit different from the other. I studied pics frm other build sites adn compared them to the plans to verify the way that the rivets need to be set. Here is the end bracket all rivetwd up. The green tape marks the holes that are not to be riveted yet. I chose to insert clecoes into some of these holes to help secure the parts better during riveting. I will remove the tape when I am satisfied that all the rivets have been properly set during this part of the build.

Just six rivets for the bracket on the outboard end of the spar:

And here is the inboard support bracket with just 5 rivets for now:

And here is the inboard end of the spar with the doublers riveted in place. All of the AN470 rivets were bucked with the rivet gun and the Fat Man bucking bar, and they turned out great. In fact, I only had to drill out one rivet, and that was because after I set it the shop head appeared to be cracked for some reason. That was a defective rivet, and it needed to come out and be replaced by another one. Still love that AN470 rivet removal tool. Worth every penny I paid for it. Just wish it was a bit less wide so it wcould be used to remove rivets inside rib flanges and such. It won't work very well in those situations so you have to make certain you set thosee rivets properly.

I will rivet the right rear spar tomorrow night and then move on to ribs - lots and lots of rib prep on deck next.

Wings 57, Total 520 Finished priming rear spar parts

Finished up priming the rear spar parts tonight. Prepped about 14 ounces this time. Still ended up with some excess in the cup, but it was close enough. Just a personal note about the primer I am using - the catalyst part number is CA-116, and that stuff is absolutely nasty to inhale when you open the 1 gallon can that it comes in. The base primer is not so bad. So I think from now on I will be doing all the mixing as well as the painting with the respirator on.

I also turned down the air pressure on the gun to about 30 psi, compared to the 45 psi I was using last night. This seemed to help prevent the orange peel problem I had last night. Just have to keep trying different things until you get the right combination of paint flow, air pressure, distance of the gun from the part, and speed of each pass of the gun.

This pic shows the gun all ready to go. Note the run on the easel paper that I used for testing. I did this on purpose to determine how long it would take to deliver too much paint in one spot before the run would occur. Short answer is "not very long."

Both rear spars, the doublers, and the support brackets are all primed!

I really do like this gravity fed HVLP (High Volume, Low Pressure) spray gun. Just wish I had a smaller one for little parts. The touch up gun I used for the empennage parts is not an HVLP, and is not gravity fed either, and I had trouble getting enough primer to flow through that gun, even after opening the paint flow knob all the way. All of the knobs on the HVLP gun work as advertised. HVLP is supposed to do a better job of applying the paint, with less bounce back, less waste and overspray, and better coverage. As far as I am concerned, that is exactly what it does.

I am fairly pleased with the parts I primed tonight. They turned out better than the ones from yesterday.  Anyway, time to slam some rivets. I just have to be careful about the rivet call outs and not to put rivets in holes that need to wait for other assemblies to be added later on.

Wings 54,Total 517 Finally priming wing parts

Wow, time flies. And now it's time to catch up on my build progress over the past couple of days. But first a couple of pics to finish up some of the dimpling prep. I decided to drill and dimple the holes on the top flanges of the aileron support brackets. Problem was that when it came time to dimple them, the female dimple die was too wide and was hitting the radius of the bend for the flange on the bracket. This would have resulted in a badly formed dimple had I not resolved this. Options were to grind down my female dimple die for the 3/32 rivet, or I could use the reduced diameter dimple die that I purchased some time ago from Cleaveland Tools. It is at least 1/8 of an inch thinner than the standard dimple die, and this allows you to form dimples on very tight flanges or oddly formed flanges, such as the over-90-degree-bent flanges on each support bracket.

I was able to dimple the flanges with no problems using the thinner female dimple die:

This next pic shows the basic fit of the parts after both the rear spar and aileron support bracket flanges were dimpled. Note the marks from the countersink cage around the countersunk holes on the end of the bracket, and the straight line marks left by the upper edge of the 3 inch yoke as the upper flange dimples were squeezed:

I think this is the first time since I began this build that I actually used a full sized scotch brite pad to scuff up the surface prior to priming. Turned out to be a lot less work than I thought, and went fairly quickly. Scuffed it with the pad, then cleaned with acetone and a microfiber cloth:

And then it was time to prime!

Here is the paint station setup that I am using. Card table same as all other times before, except this time I am also using the larger paint table and the saw horses. this worked out just fine.

Now some words about the new primer - AkzoNobel Epoxy Primer. The only thing I was worried about using this primer was if suffing the surface with a scotch brite pad was enough surface prep for the primer to adhere correctly, since most others are using alumiprep or some other chemical process to etch the metal. Short answer: Scuffing with the pad was all it took - no chemical process needed. This epoxy primer turns into a hard continuous shell when it dries. My only complaint is that it is supposed to be dry to the touch after 15 minutes, and dry to stack in an hour, and that is if it is about 70 degrees outside. Well, it was 90 degrees here today, and this stuff was only starting to get tacky at 15 minutes. It took about another 10 minutes or more before it was dry to the touch and finished flashing out.

The two plastic pour spouts I picked up from HD, and they sure came in handly, because these two gallon cans came filled to the absolute top of the can, which was something I was not expecting. The pour spouts allowed me to pour the contents from the cans into my mixing container without too much mess, and it looks like they are standing up to the chemicals of the two part primer, so I should be able to reuse them.

The material data sheet for this primer says to mix each part 1:1. Then you let it sit for a half hour before it is time to use it. The new spray gun worked great, except it is definitely designed for doing much larger coverages than the touch up gun I ahve used on all the empennage parts in the past. Results from priming once I had the paint flow and air flow settings where I wanted them was that I got a little bit of Orange peel, but not too bad. I think this happened ebcause of the extra hot temperatures today. The paint cup holds 20 ounces, but I only mixed up about 18 for this first run.

I started with the easel paper. Actually I should back up a bit first. The instructions with the spray gun ($14.00 from HF) said to run solvent throught the gun before using it because it was prepped with some anti corrosive agents before it was shipped to the USA. So I loaded up the cup with some acetone and sprayed the paper until the acetone was all gone. That should have cleaned out any residue from any packing grease or oils. The color is actually a pleasant looking greenish tint:

And now for the fun part. I found out that 18 ounces let me do almost all sides of all the small parts, including the rear spar support brackets and doublers, and the tie down bracets and spacers for both wings, and one complete side of a test trim piece that I scuffed and cleaned and painted first. I was also able to run the test passes shown in the paper above, and one side of the left rear spar, before I ran out of primer in the cup. So I only have one side of one of the doublers, one side of the left rear spar, and both sides of the right rear spar to do before it will be time to ound some rivets again.

The center part is the .040 trim piece that I used for creating test dimples and such.

And then came the cleanup. Acetone seemed to work just fine. A few wipes of the gun and inside the cup after running a small amount through the gun seemed to clean it all up just fine.

And lastly for tonight, I pic of my new PVC air line that I purchased from HD to ensure that the lone was clean and free from possible contaminants. I ahve been using the green colored line for so long, and I had it hooked up to an oiler for the paint shaker, and hooked up all winter long without changing the compressor oil or draining the tank. Just thought it would be safer to use a new air line since I have seen what happens to the paint if contaminants are present. Oh, and yeah, yeah, what a mess, I know. I have a retractable air hose reel that I just have not taken the time to install up in the rafters, but if I have time tomorrow I will start that process, so I can get the hoses off of the ground for a change.

Wings 51, Total 514 Drilling and Dimpling Rear Spar

Last night I finally executed the plan that devised to drill and dimple the necessary holes in the rear spars and the aileron support brackets. To start with, you have to understand that the flanges on the support brackets are bent over 90 degrees to the web, so that means that the angle required to drill holes correctly in the top flange must alos be done at the same angle. Decided to guesstimate this by using the reflection in the alclad aluminum to determin if the drill bit was pernedicular to the flange after clamping the spars to the edges of my saw horses. This worked out just fine I think. One or two of the holes in each support bracket flange may be slightly misaligned from the others, but not to the point where I have to worry about anything.

The above setup allowed me to sit down with the drill at almost eye level so I could focus my attention to the correct angle to hold the drill on the spar flange. Was largely a non-event.

Here the aileron support bracket is clecoed to the rear spar, and the upper spar flange is in position for drilling. I am glad I made the decision to drill these holes now, because they all needed a fair amount of deburring for some reason.

And this is one of the outboard brackets after the holes are drilled and deburred:

And finally is really crappy blurry pic of the inboard upper spar flange holes that must be dimpled ahead of time You can't tell from the pic that the first 10 inches-worth of holes are dimpled with the tank dimple die, but that is what I did to account for the thickness of the wing skin as well as the wing walk doubler plate whose dimples will both need to fit inside the dimples in the spar flange. You must dimple these holes before riveting the spar doubler support brackets in place, because the thickness of the heavy support brackets makes it impossible to get a dimple die in that area afterward. I did the inboard holes with the tank dimple dies in the standard 3 inch yoke with my hand squeezer, and the remaining holes with the standard AN426AN3 dimple dies. For now you only need to dimple the holes up to the end of the length of the forks on each support bracket.

One thing that happens when you dimple these holes, again because of the over 90 degree angle of the spar flange, is that small marks will be made on the spar web from the tip of the yoke. They are not deep and will be scuffed away when the parts are prepped for priming. Just another annoyance with tools that don't quite properly do the job without making some modifications. In this case I would have had to grind down more of the tip of the yoke so that it would not hit the web of the spar as you formed the dimple with the squeezer. I did not do this because I read about the marks in other posts from other builders, so I knew they were nothing to worry about. Riveting them, of course, will be another story, because I will not want to make the same marks after the skins are in place and everything is primed. So that will be a job for the no hole yoke, to ensure that the tip will not interfere with the spar web.

I will say this - I once again used a hand squeezer here instead of that damn air squeezer because I did not want to risk making deeper gouges in the spar web than necessary. I enjoy the better control with the hand squeezer emensly for areas where extra care needs to be taken.

The only thing I think I need to do is dimple the flange holes that I just drilled for the aileron support brackets and the matching holes in the spar flange, but I need to think that one through as well.

On a cool factor note, I attended our monthly EAA Chapter 301 meeting tonight, and saw a presentation by a local builder who appears as though he will be one of only 3 people with a flying kit built replica of a Nieuport 28 WW I biplane fighter in the not too distant future. He presented a snapshot of the kit and the building process. He even already has the replica machine guns to go with it.

This is a way cool kit, and I can't wait until he finishes and flies it. Apparently the owners of the other two flying Nieuports are both in Texas, and one of those is also finishing up a Sopwith side by side seat aircraft, one of which may be at Oshkosh this year. ONe other interesting tidbit is that he used standard BEHR latex house paint to paint the fabric covered wings, because he says that the weight of 4 coats of that paint is actually less than dope or any other polyurethane paint on the market. Very cool stuff indeed.

Wings 50, Total 513 Made Decisions for Final Support Bracket Work

I think I reached some decisions about countersinking or dimpling several of the holes in the outboard aileron support brackets, an also for the skin attach holes on the inboard section of the rear spar. But first.... almost done with the shed doors. Just a small amount of painting left to do and I'm finally done with that fiasco.

New doors in progress:

Looks kinda funny - brand new doors on a scrappy looking shed, but oh well. Maybe it will last a few more years before the whole shed needs to be replaced.

So I decided to countersink the 4 holes on the outboard-most edges of the two aileron support brackets instead of dimpling them as someone at Vans suggested. The reason is that I did a sample countersink on a piece of .040 scrap aluminum from the trim bundle that I received from Vans, and I also checked the info in Chapter 5 of the manual. The spar and the support bracket are both made from .040 thick aluminum.

The manual shows a pic with 3 examples for countersinking. One with a top skin thicker than bottom skin, one where both skins are the same thickness, and one where the top skin is thinner than the bottom skin. The one where both skins are the same thickness, which is also the case for the assembly of the brackets to the rear spar, shows that the minimum acceptable countersink situation is where the countersink just hits the bottom of the thickness of the top skin, or in other words when you countersink you do NOT go deeper than the thickness of the top skin.

I was able to achieve this by countersinking the holes, whereas the guy at Vans was telling me that I would end up countersinking into the rear spar just a bit if I did this. Several other builder sites and my own test countersink confirmed that this works just fine. If I dimpled the support bracket, I would also end up needing to dimple the rear spar and the rib flange, and I was just not going to go there.

This pic shows a trick that I had tried a while back when countersinking the nut plate rivet holes for the spacers for the tie down and aileron belcrank brackets (when my countersink bit broke.) I butted the two brackets together on the last hole to provide enough surface area for the countersink cage to rest on so that I could create a good countersunk hole.  Worked pretty well on both holes.

For the hole closest to the top flange of the bracket, you cannot get the countersink cage to fit in this area at all, so out came my cordless drill and the deburring bit that I have used to create countersunk holes for the elevators. The first one ended up a bit oblong for some reason, and I was able to clean it up enough by finishing it by hand instead of letting the drill do all the damage. I think this happened because I did not support the deburring bit with my fingers as I started the hole.This allowed it to grab and wonder in the hole just a bit.

When I did the bracket for the right side I spent more time finishing the hole by hand - harder on the hands and fingers, but the hole came out much better. I used the deburring bit in the drill to start the hole and get it to a certain depth where the head sits just proud of the hole, and then I removed the bit from the drill and turned it by hand a little at a time until I was satisfied with the fit of the flush rivet head against skin on the bracket. These rivets must sit absolutely flush because an angle support bracket for the aileron hinge gets placed directly over the top of them, and the angle sits flush against the support bracket. The ailerons will get used a lot for banking the aircraft, so the hinges need to be securely fastened.

And finally both brackets with countersunk holes, next to my test piece of aluminum where I tested the countersink before doing it on the actual parts:

For the inboard skin attach holes, I decided to use the tank dimple dies on the first 9 inches of holes on the top flange of the rear spar, because there is a doubler skin that goes over the main skinthat is about 9 inches wide by 26 inches long, and the two skins then attach to the rear spar flange. The tank dimple die gives a slighty deeper dimple (also tested this on the scrap .040 aluminum), and this will allow the additional doubler skin and the inboard wing skin to sit in the dimple on the rear spar flange nicely I think. The remaining spar flange holes that make up the remaining length of the doubler fork can be dimpled with the standard dimple dies, since only the wing skin attaches to these holes. I used a test piece of .032 thick aluminum with a 3/32 dimple to verify the fit.

What is the doubler skin for you may ask? This is the platform on top of the wing that everyone will stand on so that they can step into the cockpit of the aircraft, and take the ride of a lifetime. I think that this approach will work out well.

Lastly, there are 4 skin attach holes on the outboard support bracket that I think I will also predrill to #40. Vans told me to leave those until I assemble the wing skins, but the more I thought about, I realized that the skins will need to be clecoed to the spar, and until these holes are drilled through the solid bracket flange, I will not be able to insert the clecoes. The other reason is that I want to be able to debur the holes in the support bracket flange. If I go ahead and rivet the bracket to the spar without drilling and deburring the holes first, I will not be able to debur them later. So there is no time like the present to make sure all the holes are clean.