Archive for April, 2012

Main Spar Prep Done

April 28th, 2012 No comments

Nutplates All Done

Saturday arrived and since I had done the yard work earlier this week, I was ready to have a decent day in the shop. First order of business was to spot prime all the nutplate attach rivet countersinks and rivet on the 150 nutplates to the spars. This took a good portion of the morning to do. That is a lot of nutplates Vans! I was able to easily reach the nutplates near the root of the spar in the center of the web with my 3″ yoke on my squeezer. I only primed the countersinks for the attach rivets because I plan to prime the entire flange once the countersinks for the skin dimples are done. As for now, the nutplates are on and look great.

Tie Down Block Work Begins

Next up on the list were the tie down blocks and spacers. I dressed the edges with my scotchbright wheel on the AEX blocks themselves and then laid out the first holes to be drilled. Van’s has you drill one with the dimensions from the plans, then run a cleco or bolt through that hole and the matching hole in the spar and then match drill the rest. Before you do that, you have to make 4 spacers that will go in between the AEX stock and the spar itself. These are made out of 1″ bar stock. I simply cut them to size with my band saw and then marked the center for the lightening hole. I debated on what to use to cut the lightening holes with. I have a fly cutter, but the 1″ hole is a little tight for it. I ended up running to Lowes Aviation Supply and picking up a 1″ Bi-Metal hole saw. I also picked up a drill press vice to hold parts on the drill press platform. Word to the wise, lube the saw. The next half hour was spent cleaning up the inside radius of the holes with a Dremmel tool with a sanding drum.

One Tie Down Block Done

Once the blocks and spacers were cleaned up, I match drilled them to the spar holes. I taped the spacers down to the spar so they would not move and then clamped the tie down blocks over them. Once drilled, you have to then match drill the spacers AND the blocks for the rivets that hold the nutplates for the aileron bellcrank bolts. After drilling I deburred all the holes and got the parts ready for primer. The parts were then primed and riveted together. Above you see the complete tiedown block/spacer assembly. Van’s designed it this way in case a nutplate had to be serviced. If one is bad, you can remove this block and replace the nutplate. Interestingly enough however, to get to the block assembly, you have to remove the tank on a finished wing. I do not see how you could get to it otherwise. I hope to not need to find out either way.

Nice and Tapped

Before you can install the blocks onto the spars, you need to tap the bottom end to accept the tie down rings that will thread into these blocks. The AEX block is pre-drilled. You have to then tap this to a 3/8-16 thread to about 1″ deep. I do not have this size of a tap, so I called around to those I thought that would with little luck. Finally, I decided to check with my back fence neighbor Jeff, and see if he had one. His is an expert mechanic after all. Turns out Jeff did…and it was a nice one. I promised not to ruin it and he handed it over. After about 5 minutes and some bo-lube, I was able to get these nicely done and they look great and straight. I cleaned up the tap and ran it back over. Thanks a bunch Jeff! (Incidentally, Jeff’s son Pat is an aviation tech for the USAF in Korea, and currently works on A-10’s!)

Both Wing Tie Downs Complete

Here you can see the assemblies bolted on on both spars. I torqued the bolts to spec. It seems so weird to only torque these to 25 in/lbs. Seems light, but it is right.

Aileron Brackets On

Here are the aileron bellcrank brackets bolted on and torqued to spec as well. I torque sealed them too. Turns out, I should have waited as I need to take at least one off to install the autopilot servo bracket. However, I can just clean off and re-torque.

Spar Prep Done...ish

Here is another shot of the tie down assemblies and spacers. As it stands for now, the main spars are prepped for ribs. Next up…rear spars.

Categories: Major Wing Sections

Nutplate Location Countersinsks Complete

April 26th, 2012 No comments

Nutplate Locations Complete on Both

I was able to get the right spar nutplate countersinks done in short order. Having done the left the night prior and having the angle pre-drilled made for really quick work. Having my 3 countersink cages already set was great too. I spent the rest of the night getting hardware into bins for easier access and organization. I hope to have the spar prep complete this coming Saturday.

Categories: Major Wing Sections

Left Spar Nutplate Countersinks Complete

April 25th, 2012 No comments

Chatter Free Countersinks

I was able to get some time in the shop tonight and continue the prep work on the Left Spar. I needed to countersink the nutplate locations for the #8 screws that hold the tanks to the spar. Additionally, I needed to countersink for the #6 screws on the bottom that hold the inspection covers on. These countersinks are a challenge only because they are deep enough to open the hole wider than the pilot of the cutter and can allow for it to move around once deep enough. You have to use something beyond the flange to hold the pilot after it cuts the countersink beyond the flange. I have read several build sites that describe what can be done to accomplish this task. Van’s states that you can install the nutplates first and then use the nutplate as guide for the pilot of the countersink. That seemed a little hokey to me, but several builders said that it worked OK. I guess I just did not like the idea of possibly ruining the threads of the nutplate with the pilot of my cutter and the possible chips that could get lodged in between the nutplate and the spar flange.

Another option some have used was to use a piece of 1/16″ aluminum angle to back the holes that are to be countersunk. You simply clamp it to the flange and match drill the holes to the angle and then use it to keep the pilot centered in the hole. Since I had my angle from the rudder lying around, I decided to give this technique a shot. In the above picture, you can see that I have clamped the angle to the flange and have already match drilled the center holes with my #21 bit. I then used some clecos to hold it down the flange as I clamped it closer with some alligator clamps.

I then worked my way down the flange with my #21 piloted, 3 flute countersink. I tested the depth of the countersink in some scrap. I was aiming for a 0.370″ wide countersink (Van’s states it should be between 0.365″ and 0.375″ in diameter) and was spot on. As I would countersink, I would let the countersink cage nearly bottom out, then remove the chips, then finish the hole. This left a very nice, chatter free countersink. I figure that at .0370″ I can still adjust if needed, but many report that it will work great as is. As each was complete, I leapfrogged the two clamps so I could hold the angle tight to the flange.

How I did the Countersinks

Here you can see the angle down the length of the spar flange. The important thing is to not let it wander as the countersink is cutting. This is what eliminates the chatter.

The #6 Screw Holes In Works

Here you see the #6 holes for the inspection covers to spar interface. I used the same piece of angle to back these up. I simply offset the angle until I had no overlapping holes from the #8’s and match drilled them with #30 bit. I then used my #30 countersink cutter in a different cage set up to cut a countersink with a 0.312″ diameter. I found that Van’s recommends a countersink no greater than 0.3125″ for #6 screws. I tested on a scrap piece and then hit these. They come VERY close to the edge of the flange, but according to other builders, that is expected. Once complete, I was left with many shiny and chatter free countersinks that are ready for nutplates. The angle backer trick appears to have worked nicely. Now I simply have to repeat the process on the right spar. Thankfully, the angle I match drilled should line up with the holes already in it from this spar. I simply need to clamp and cut.

Left Spar Countersinks Complete

It was bed time for the kids and I just finished the countersinks and was cleaning up the shop when I got some visitors. My second son Alex is a real curious one, so we chatted a little as to what the gold thing was on the bench. I asked my wife to take a shot of me working/posing with the parts and he weaseled in the shot. Hopefully his curiosity sticks because I will need a bucking partner on the wing skins soon enough. With everything learned on the first spar, the hope is that the second will go a little faster.

Categories: Major Wing Sections

Wings Begun, Spar Countersinking on the Left Spar

April 19th, 2012 No comments

The Tank Nutplate Countersinking Begins

I had originally planned to take the day off from work to participate in a State/CAP exercise. The State of Utah decided that our assistance was not needed and they were going to spin down. So I had the day off…and I debated if I should go in to work or use it for fun. Fun it is. I spent most of the day building an empennage cart to store my finished tail parts in and get them out of the way. I will outline that in a separate update.

Once the cart was complete, I organized the wing kit crate parts and emptied the the crate. I also emptied the spar crate and pulled the spars out of the shipping plastic. After a close inspection, and only finding some minor nicks, I decided to start with step one of the wings…countersinking all the nutplate attach holes for the tank/inspection cover screws. So I chucked up my #40 piloted countersink in its preset cage, ran a test hole in some scrap, and started on the #40 holes on the spar flange of the left spar.

They are Gold in Color for a Reason

You can see here that I used some masking tape on the spar. This was to protect the GOLD anodization as well as keep chips from the countersinks from falling into the valley created by the spar channel and the spar bars. It works great. The spar is a work of art. It still amazes me that this chunk of metal can withstand +6 G’s. Engineers are cool. Once all the #40 holes were done on the top, I flipped the spar over and did the bottoms. I used my cordless drill on the low speed setting. More torque, no chatter. I tested all the holes by dropping a rivet in. Every one of them is perfect.

Nutplate Attach Holes 1 Spar

I was able to get all the #40 holes done on the left spar and then the battery died on the drill. It was late anyway so I called it quits. I think I will use another trick I saw on the larger holes. Basically, I will match drill the larger holes with and #21 bit to a cheap piece of aluminum angle picked up from the local Lowes aviation supply. Then I will countersink the holes with my #21 piloted countersink to the correct depth for a #8 screw. The aluminum angle will provide more meat for the countersink pilot as these holes will end up with a knife edge on the bottom. This should eliminate chatter in these holes because the pilot will not wander as the hole in the spar flange opens up. Van’s has you install the nutplates and then use them for centering the pilot…hmmm.

We’ll see how it works out in the next couple of days.

Categories: Major Wing Sections

Preparing for Wings

April 14th, 2012 No comments

Building the Wing Stands

I have had the wing kit in the shop since it was delivered with the tail kit back in April of last year. I opened it up and did the inventory at that time too. It has been taunting me ever since. I have been researching several builder sites as to how they set up their shops for the wing spar stands. Vans has you make them from 4″X4″ wood posts that extend floor to ceiling. I did not like this design as it limits where I can set it up in my shop due to the over head garage door. That, and the wood could warp over time, though unlikely here in Utah.

I really like the setup Rudi Greyling from South Africa devised. Basically he made the stands out of 2″X4″ tubular steel and bolted them to the floor of his shop. I have a friend/co-worker that used to be a pro-welder. We chatted it over and came up with something very similar in design. Instead of using angle for the feet like Rudi did, we decided to make a foot out of the same tube and weld it on. Each post will be bolted to the floor with 2 bolts instead of 4 like Rudi’s design called for. Basically we cut a 45° angle on one end of the foot and 22.5° angle on the other side. This made a nice trapezoid shaped foot. The reason for the 45° on one end was to give a little more leverage to the foot on the side that the spar will hang on.

In the picture above, you can see my son Taylor and me cutting one of the feet out with a torch. My welder friend insisted he learn…and so he did. Taylor did GREAT!! My friend was impressed with his steady and straight cuts. We traded off cutting out all the parts and getting them ready to weld together. It took a good 2 hours with all the grinding involved. I was amazed the torch cut through 3/16″ steel tubing like butter.

Once all the parts were prepped, my welder friend tacked the feet onto the posts and then finished the welds. That man can move and does a really good looking job welding. I used some scrap flat bar stock to cap the top of the tubes. All I need is to drop a tool down the 4′ tubes and not be able to get it out. He let Taylor try his hand at welding too. He did OK. He then had me do a couple of beads and then he finished up. I think these will be very sturdy and work well. I still need to file them down and clean them up for paint, but the hard part is done. Thanks Russel!

On the way home, Taylor looked over at me and said, “That was cool!” Made all the aches and pain worth it!

Once cleaned up and painted, I will get them installed in the shop.


Categories: Wings