Archive for category Spars
Tie-Down Assemblies Bolted to Spars (7/1/10)
Posted by Ethan Jacoby in Construction, Spars, Wings on July 2, 2010
1.5 Hours -
The tie-down bracket parts have been sitting in the garage on a piece of cardboard since I primed them almost a week ago. Tonight, I finally had time to get some airplane work done, and, thanks to hurricane Alex, the garage was a chilly 80 degrees!
The first step was to rivet the tie-down brackets together. Each tie-down consists of a bracket, two spacers, and two platenuts. All of these are held together using a few AN426AD3-7 rivets.
Forward view of the finished tie-down assembly.
Aft view of the finished tie-down assembly. Um...what happened to my lightening hole on the left?
Once the assemblies were riveted together, it was time to see if everything still fit the spar correctly. For some reason, I’m still surprised when everything goes back together the way it was supposed to. I was even more surprised this time, since the tie-downs are almost completely fabricated from scratch.
Finally, I bolted the tie-downs to the main spars. Each tie-down bracket is held in place by 8 bolts. The bolts on the top and bottom only hold the tie-down to the spar, while the middle 4 bolts also attach the W-823PP bellcrank brackets to aft side of the spars.
The tie-downs are now bolted to the spar.
The bolts for the tie-down also attach the bellcrank brackets.
Once all the bolts were tightened up, I torqued them appropriately and applied some torque seal to remind myself that they are done. Next up…the rear spars.
Torqued and torque sealed!
Finishing the Tie-Downs (6/27/10)
Posted by Ethan Jacoby in Construction, Spars, Wings on June 27, 2010
1.5 Hours -
After a little more work on the tie-down assemblies, they are essentially finished.
I started by drilling four platenuts to the right assembly. These are used for bolts that will hold the elevator horn brackets, as well as the tie-down and spacers, to the spar. Once this was done, I moved on to the left tie-down, where I still had to match drill it to the spar and drill the platenuts.
A platenut jig probably would have been easier, but a bolt and a cleco worked well too.
With everything drilled, it was time for that fun process of finishing the edges, scuffing with a Scotchbrite pad, cleaning with acetone, and priming. I left the primer to dry overnight. Tomorrow, I’ll rivet together the tie-down assemblies and bolt them to the spar.
More priming!
Tie-Down Assemblies Started (6/26/10)
Posted by Ethan Jacoby in Construction, Spars, Wings on June 27, 2010
1.2 Hours -
After installing all those platenuts on the spars, I was happy to move on to something different today. The wing tie-down assemblies are incredibly simple. They consist of a piece of extruded aluminum and two spacers which are attached to the spar.
The first step is to tap the extruded aluminum pieces so that the tie-down eye bolts can be screwed into them. I’ve never tapped anything before, so I chose to do this first just in case I ruined the pieces. After all, one ruined piece is easier to replace than three!
The tap is used to make threads for the tie-down ring to screw into...this should be interesting.
A couple minutes into tapping the first tie-down, I realized that using a tap wasn’t rocket science. Since the extruded aluminum already has a hole in it, there was no problem starting the 3/8-16 tap and keeping it straight. One turn to the right, followed by a quarter turn to the left, back to the right, repeat for about 5 minutes, and done.
Getting the tap started was much easier than expected. The hole in the aluminum made it easy to get started and keep the tap straight.
At about the halfway point, I decided I better check the fit. Another 1/2" to go.
Next, one of the top holes is drilled into the tie-down. This is the only hole that is drilled by measurement, the rest are drilled using the spar as a guide. I drilled this hole in both tie-downs and then sat the left tie-down aside since my right spar was already on the bench.
The first hole is drilled off the spar at a set location dictated by the plans. The rest of the holes are drilled using the spar as a guide.
Before drilling the remaining 7 holes in the right tie-down, the tie-down and spacers have to be clamped into place. Like other builders, I used tape to hold the spacers in place, then used a square to make sure the tie-down was straight before holding it in place with a c-clamp. Once everything was in place, I drilled the rest of the holes with a 3/16” bit.
The only way to keep the spacers in place is to tape them. The tie-down is clamped on over these.
Appropriately, I used a square to square the tie-down.
The rest of the holes were drilled from behind using the pre-drilled holes in the spar as a guide.
Fortunately, the spacers stayed in place throughout the process.
Once all the holes were drilled, I removed the clamp and tape and then carefully marked the orientation of each part so that I can put everything back together correctly.
Tomorrow, I’ll drill the platenuts in the right tie-down and try to finish up the left as well. Then, all the pieces can be primed before finally be attached to the spars.
Right Spar Platenuts Finished (6/25/10)
Posted by Ethan Jacoby in Construction, Panel/Wiring, Spars, Wings on June 26, 2010
1.3 Hours -
Although the garage was hot, I managed to spend just over an hour finishing the platenuts on the top of the right spar. As before, I had to countersink the holes for the rivets, attach the platenuts, and countersink the center hole for the #8 screw. Once this was done, I primed the countersunk holes.
For breaks in the “fun’ that is countersinking, I started finishing the edges of my tie down spacers. For now, I just used a vixen file to smooth the outside edges. I’ll still need to smooth the inner, lightening hole edges.
I also received my first panel instrument today, a Garmin Aera 510. My girlfriend works for a Garmin fitness dealer and, even though they only sell Garmins for running and cycling, she was able to get me a great deal on the 510. This GPS will serve as my backup GPS. It may even serve as several other backup instruments since I’m building a VFR only airplane. It has an incredible amount of functionality built into such a small box. In addition, the 510 has built in XM weather. While I don’t plan on subscribing to XM, I figured it may be a nice option to have available once I start doing longer cross-country flights. The only decision now is whether I mount it in an Airgizmo panel mount, or make my own mount somehow.
Garmin Aera 510
Although small, the screen is surprisingly easy to read.
Less than an inch thick, but a little heavier than I expected it to be.
Started the Right Spar (6/20/10)
Posted by Ethan Jacoby in Construction, Spars, Wings on June 20, 2010
2.5 Hours -
I was only able to work on the plane for short periods of time, off and on, today. Therefore, I was surprised that I hit the 2.5 hour mark!
It was nice and cool this morning, so I started in the garage early. My primer was dry on the bottom of the left spar, so I riveted the 12 platenuts, which will be used to attach the inspection covers using #6 screws, to the bottom of the spar.
The platenuts on the top are for the inspection covers, the ones on the bottom are for the fuel tanks.
Just a picture of the underside of the spar after all the platenuts were installed.
Then, it was time to move on to the right spar. I pulled it out of the plastic bag Van’s ships it in. As with the left spar, the right was in perfect condition. I really like the gold anodized finish that the factory puts on it as well.
First off, I taped the gaps in the spar. While blowing out the left spar after I was done worked well enough, I decided I would use tape this time to make it even easier. Then, I started working on the bottom side of the spar.
This time, I decided to tape over the gap to keep all the aluminum shavings out. On the left spar, I didn't do a good job of keeping the tape on.
On parts of the empennage, the second one always seemed to go faster. The spars are no different. I was able to drill, countersink, and prime the bottom of the right spar in about half the time it took to do the same work on the left. Not only was it quicker, but I think my work was better as well. Once my primer dries, I’ll attach the platenuts for the inspection covers and start working on the top side of the spar.
If anyone is counting, at this stage of the game, I’m attaching 74 platenuts on each spar (more will be installed on later steps). That’s 220 holes that must be countersunk per spar, and I’m just getting started!
Later in the day, I returned to the garage to rivet on the inspection cover platenuts on the bottom of the right spar. Getting tired of countersinking, I decided to start working on the tie-down spacers instead of starting the top side of the spar.
The tie-down spacers are fabricated from a strip of aluminum provided in the kit. They are simply a 2” X 1.5” x 1/4” pieces of metal with a 1 inch diameter lightening hole cut into the center. However, these proved to be a bit more of a challenge than I expected.
I marked the aluminum strip for the first two spacers. To mark the center of the lightening hole, I used my center punch and then drilled the punch mark a little bit simply to provide a nice starting point for the fly-cutter.
I marked the center of the spacer and punched it. I enlarged the punch slightly with a #40 drill so that it would be easy to start the fly cutter.
Next, I pulled out my fly-cutter for the first time. It was easy enough to set this up for a 1” diameter hole, but actually using it was quite the experience. Once the cutting blade hits the aluminum, it is extremely loud and aluminum chips fly everywhere. In addition, the cutter is horribly balanced, causing the drill press and entire table to wobble. Safety glasses are a must with the fly-cutter!
Once the fly cutter starts to cut a circle, it is noisey and a little scary.
The cutter didn’t want to go through the entire piece due to the aluminum’s thickness. Once the cutter was about half way through, I would have to flip the aluminum over and start cutting from the backside. The resulting hole is a little rough and will need some finishing work.
I had to cut half-way through, then flip the spacer and finish from the other side.
One down, three to go.
Once the lightening hole was cut, I used my Dremel with a cutting wheel to cut the spacer from the rest of the aluminum stock (the band saw didn’t like this thick aluminum). The entire process was repeated three more times in order to end up with 4 spacers. The edges of the spacers will get finished another day.
I used my Dremel with a cut-off wheel to seperate the spacers. Now they need some finishing.
A Couple More Platenuts and Some Primer (6/18/10)
Posted by Ethan Jacoby in Construction, Spars, Wings on June 18, 2010
0.5 Hours -
Not much to report.
I countersunk the aft side of the spar for two more platenuts that will go on the forward side. Countersinking the wrong side of the spar here could be costly, so I looked at the plans rather closely.
Two platenuts are attached to the forward side of spar...you have to be very careful that you countersink the correct side.
Then, I primed the top of the left spar since all of the countersinks were completed on that surface. I didn’t want to waste time just dabbing primer into the countersunk holes, so I masked off the entire surface, wiped if off with some acetone, and sprayed a coat of NAPA 7220 self-etching primer.
After all the countersinks were completed, some NAPA 7220 was used to cover any areas where the anodization layer was removed.
More Countersinking on the Left Spar
Posted by Ethan Jacoby in Construction, Spars, Wings on June 17, 2010
1.3 Hours -
Back to countersinking again tonight. For some reason, I really hate countersinking. However, I’ve found it to be a bit easier when I use my electric drill vs. the air drill. Maybe it is the slower speed/higher torque of the electric drill, but it seems to produce a nicer countersink with less chattering.
I finished countersinking all of the holes for attaching platenuts in the left spar flanges. All that I had remaining were the holes used for attaching the inspection covers. Then, I riveted on all of the tank attach platenuts to the top of the spar. Once riveted on, I used the platenut as a guide for countersinking the center hole for the #8 screws that will be used to attach the tanks. Over an hour of work, and I still have to finish all of the platenuts on the bottom of the spar…and all of the platenuts on the right spar. Just a little repetitive.
After countersinking the outer holes, the platenuts can be riveted onto the spar.
The platenuts are riveted onto the underside of the spar.
Once the platenut is riveted on, the center hole can be countersunk for a #8 screw.
Me countersinking. I'm using the air drill here, but I think I prefer the electric drill for this task.
Countersinking Left Spar (6/15/10)
Posted by Ethan Jacoby in Construction, Spars, Wings on June 16, 2010
0.7 Hours -
My replacement #40 countersinks arrived from Avery Tools this afternoon. As usual, Avery’s service is great. Items I’ve ordered from Avery often arrive next day (it helps that they are in Dallas…about a 4 hour drive from San Antonio).
While I wasn’t planning on doing any airplane work this evening, the spars called to me as I passed through the garage after returning from the gym. Fortunately, it had cooled off significantly and the garage was almost comfortable once I turned a fan on.
After setting up the new countersink cutter in the cage, I finished countersinking all of the hole in the left spar that are used for attaching the fuel tank platenuts. Unfortunately, this is only about 75% of the holes that need countersinking in the left spar, and the right spar is still untouched!
Next up, I’ll rivet on all of the platenuts. Then the center hole for the screw can be countersunk.
Countersinking is relatively simple. You just have to setup the countersink cage for the appropriate depth and then start drilling. However, this gets really repetitive on the spars. I’ve also noticed that I don’t use consistent downward force when countersinking, causing some holes to be countersunk appropriately while others are too shallow. This adds more time to the process as I feel that I need to check every countersink for appropriate depth by placing a rivet in each hole and checking that the head is flush with the spar. Oh well, I have plenty of time.
Sorry, no pictures today.
Started Drilling Left Spar (6/13/10)
Posted by Ethan Jacoby in Construction, Spars, Wings on June 13, 2010
1.5 Hours -
My Dad came over this afternoon, and we got started on the spars. However, we didn’t make it very far. The first step is to attach a bunch of platenuts to the spars. To do this, the holes in the spars have to be drilled to size, then they have to be countersunk. Well, my #40 countersink lasted about 10 holes before the guide broke off. The rest of the #40 rivet holes will have to wait until I get a new countersink bit.
My Dad started drilling the spar while I set up the countersink.
After my Dad left, I went back into the garage and attached the first few platenuts (all of the ones that had been countersunk). For the screw hole, I’m going to use the Van’s method…rivet the platenut on and then use #30 countersink on the screw hole. Rather than making a guide from scrape aluminum, the platenut acts as the guide for the countersink bit. I set my countersink up for a .370″ diameter countersink and went to work. This method seemed to work well for the first few holes, so I think I’ll stick with it.
The first few tank attach platenuts are installed...the rest will have to wait until I get a new #40 countersink bit.
Van's recommends a countersink diameter of .365"-.375" for a #8 screw. I set up my countersink for the middle.
Hopefully, I can have a new #40 countersink delivered within a couple of days. No real rush though as I can only work on the plane in the evenings during the week, and the heat at that time of day greatly limits the amount of time I want to spend in the garage.
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