Archive for category Spars
Left Tank On Wing (12/14/10)
Posted by Ethan Jacoby in Construction, Fuel Tanks, Main Structure, Spars, Wings on December 14, 2010
2.7 Hours -
The left tank couldn’t go on the wing until I finished prepping the spar, and I still had some countersinking and priming to do on the top side of the spar. To get to this area of the spar, I had to remove the top, inboard skin (the only skin I still had clecoed to the wing) and the wing walk doubler. I removed these two pieces from both wings and finished countersinking the fuel tank area of both spars. After finishing countersinking, I primed the area and moved on to another task while the primer dried. Fortunately, this is the last countersinking I have to do on the spars.
While the primer on the spars dried, I started working on the wing walk doublers. These only had to be deburred, dimpled and primed. Most of the dimples could be done with my squeezer, but some of the holes in the two middle rows had to be dimpled with the c-frame. Because the top sides of the doublers are completely covered by the wing skin, I decided to prime the entire surface, front and back, of the doublers rather than just priming the rivet lines. These can now be set aside until it is time to rivet the top skins.
The wing walk doublers are ready for primer after being deburred, dimpled and scuffed.
The wing walk doublers post primer
Next, I set a few rib to spar rivets that are not used to attach the skins and get covered when the tank is in place. The plans are unclear about how to handle these rivets. In fact, I couldn’t even find them on the drawings. It looks like other builder’s are mixed as to whether or not to even set rivets in these locations, but I decided setting rivets here couldn’t hurt, and, since they could all be squeezed, it wasn’t a difficult or time consuming task.
The left tank on the wing!
Finally, it was time to install the tank on the left wing. After setting the tank on the spar and sliding it into place over the leading edge joint strip, I loosely installed all of the screws. By doing this, I was able to slightly nudge the tank into proper position and line up the bolt holes. Then, I loosely installed 6 of the z-bracket bolts. So far, everything has lined up perfectly. Once I loosely install the rest of the bolts, I’ll go back through and tighten everything down. Right now, it looks like by leading edge/tank gap will be acceptable without having to install any shims.
After setting the tank in place, I loosely installed some of the bolts.
I also loosely installed all of the tank attach screws. It looks like the joint between the leading edge and tank will be nice and tight.
Riveted Right Leading Edge to Spar (12/13/10)
Posted by Ethan Jacoby in Construction, Leading Edges, Main Structure, Spars, Wings on December 13, 2010
1.0 Hours -
Tonight, I finished riveting the right leading edge to the spar. As with the left side, all of the skin to spar rivets could be squeezed.
Once the leading edge was riveted, I spent a few minutes removing the rest of the blue vinyl from the leading edges.
Next up, I need to finish countersinking, deburring and dimpling the wings.
Leading Edge Riveting/Left Fuel Tank Test (12/12/10)
Posted by Ethan Jacoby in Construction, Fuel Tanks, Leading Edges, Main Structure, Spars, Wings on December 12, 2010
3.5 Hours -
The first task on my to do list today was to rivet the leading edges to the spars. I’m not deviating from the plans very often, but this is one case where I did. The plans call for solid rivets to connect the leading edge ribs to the main wing spar. Even with a riveting partner, I think this would have been very difficult. Instead, I opted to substitute pop-rivets, a tactic many other builders have used here. My rivets of choice are MSP-43s and MSP-44s. Based on their rated strength, they should be more than adequate.
The space for installing the leading edge rib/main spar rivets is very tight for all but one of the ribs. I had to use my modified rivet puller (with one side ground down), along with an angled rivet spacer that I described in an earlier fuel tank post. The spacer allows me to put a slight bend in the shank of the pop-rivet, giving me more space for the rivet puller, while still allowing me to apply even force across the entire rivet head. Using this method, my arms were still exhausted by the end of the session!
It's a tight fit for these leading edge to spar pop rivets. Solid rivets would have been a serious pain in the ass.
Once all of the leading edge to spar rivets were set in both wings, I set-up my squeezer and started squeezing the leading edge skin to spar rivets on the left wing. After these rivets were set, I was tired of riveting, and decided to leave the skin to spar rivets in the right wing for another day.
The left leading edge is permanently riveted to the spar.
Next, I installed the stall warner access cover plate in the left leading edge. There’s no real reason this needed to be done right now, except that I just wanted to get some parts off my work bench. The cover plate is installed with ten #6 screws. I was a little surprised at the size of the gap that is present between the cover plate and the rest of the leading edge skin. Generally, everything in the kit has been very close tolerance to far. Fortunately, this will be on the bottom of the wing where no one will see it.
The stall access cover has a bit of a gap all the way around. At least it is on the bottom of the wing and won't be seen.
The last thing I did today was to perform a leak test on the left tank. This is the first time I tested this tank, so I had to move all the test equipment over from the right tank. When I started to pump air into the tank with a bicycle pump, I became a bit worried when the balloon didn’t start to inflate. However, all of the sudden, when I started feeling around the balloon for leaks, it rapidly began to inflate!
I don’t think waiting for a couple days to see if the balloon stays inflated is a good leak test (plus I know there are leaks where the balloon is attached to some tubing), so I went ahead and sprayed the tank down with some soapy water. After a close inspection of all the rivets, I’m happy to report there are NO LEAKS in the left tank! Too bad I still have some leaks in the right tank to fix…
When testing the left tank, the balloon inflated and a soapy water spray-down showed no leaks!
Still More Leading Edge and Wing Prep (12/11/10)
Posted by Ethan Jacoby in Construction, Leading Edges, Main Structure, Panel/Wiring, Spars, Wings on December 11, 2010
5.0 Hours -
Time really flew by while I was working on the plane today. I started doing some simple, repetitive things like deburring, dimpling and countersinking, and, the next thing I knew, I had been working for 5 hours!
I started off by finishing up my countersinking on the left main spar. Since the left leading edge was completely assembled except for the new inboard rib, I needed to get all of the leading edge attach holes countersunk before I could start working on drilling the new rib. Since the holes in the leading edge skin were already dimpled, I needed the corresponding countersinks in the spar completed to ensure that the leading edge would fit tightly on the wing.
Once the left spar was countersunk, I clecoed the leading edge on. Before inserting the new rib, I deburred and fluted it. Then, I marked a center line all the way around the rib on the flange. This line will be visible through the holes in the skin, ensuring that I have the rib appropriately located before drilling.
The left leading edge went back onto the wing, again, to drill the new inboard rib.
I drew a line down the middle of the flange on the new rib...I will be able to see this line through the skin and ensure that the rib is being drilled properly.
After the line was drawn, I inserted the rib into the leading edge/wing. Once I could see the line on the aft rib flange through the holes in the spar, I used a 12” #30 drill to drill the holes in the aft flange using the holes in the spar as a guide. Then, it was on to the #40 holes that attach the rib to the leading edge skin. Since I could see my line, it was easy to line-up and drill the flange.
The centerline on the rib was easily visible through the holes in the skin.
Once all of the holes were drilled, I removed the leading edge from the wing, and finished the new rib by deburring, dimpling, scuffing and priming it. While waiting for the primer to dry, I did some more deburring and dimpling on the main wing structures. After the primer dried I riveted the new rib and joint plate to the left leading edge.
The top rib is the old rib with holes too close to the bend. The bottom rib is the new one...notice the holes are located properly this time.
Ready to rivet the new inboard rib and joint strip to the left leading edge.
Next, I installed the stall warner and ground wire into the leading edge. Two bolts hold this in place, and the assembly can be adjusted up or down slightly to ensure that the switch can trigger. I also installed the wire that runs from the warner into the fuselage. However, for now, this wire will just be coiled inside the wing structure with no terminal installed on the fuselage end. Before leaving the stall warner, I used my multimeter to test the continuity on my ground connection.
Then, I continued my never-ending task of deburring, dimpling and countersinking the spars and wing structure.
Finally, I clecoed the leading edges to the wings for the final time. Next time those clecoes come out, they will be replaced by rivets (finally!).
My girlfriend was playing with my camera and taking bad pictures of me...
The wiring for the stall warner runs through a snap bushing in the spar.
The leading edges are clecoed onto the wings for the last time. Next time the clecoes come out, they'll be replaced by rivets!
More Countersinking and Wing Prep (12/10/10)
Posted by Ethan Jacoby in Construction, Leading Edges, Main Structure, Panel/Wiring, Spars, Tools, Wings on December 10, 2010
2.3 Hours -
Tonight, I resumed countersinking the left spar. I finished countersinking the bottom of left spar and the leading edge portion of the top of the spar. To do the top, I had to remove the outboard skin. Now, I just have the top/inboard of the left spar and the entire top of the right spar remaining to be countersunk.
Once I finished countersinking for the evening, I cleaned the spars with acetone and sprayed some self-etching primer to cover the exposed aluminum in the countersinks.
After countersinking the main spar, I cleaned it and sprayed some self-etching primer.
Ready for a break from countersinking, I decided to make the ground wire for the stall warner system. This was fairly quick to complete since all I had to do was to cut a 3.5 inch piece of 18 gauge wire, strip both ends, and crimp on terminals. To crimp the terminals, I ended up buying a ratcheting crimper from SteinAir. The dies on the crimper are interchangeable, and I purchased dies for both RBY and BNC terminals.
I bought this ratcheting crimper from SteinAir. It has dies for both RBY and BNC terminals.
Nothing complicated...the stall warner ground wire is a 3.5 inch piece of 18 gauge wire with terminals crimped on each end.
Finally, I started deburring and dimpling the left wing structure. Trying to break up the monotony, I would deburr a rib and a portion of the rear spar, then dimple those sections. Changing tasks like this seems to help me work longer. However, there is still a lot of countersinking, deburring and dimpling left to do in the wings.
Rear Spars Assembled (7/17/10)
Posted by Ethan Jacoby in Construction, Spars, Wings on July 17, 2010
2.0 Hours -
It took me two hours to assemble the rear spars. At least when I was done, it looked like I accomplished something.
Assembly of the rear spars is the first bit of real riveting in the wing kit and you really have to pay attention to which rivets to use and where to use them. Many holes are left open for later assembly with ribs, aileron brackets, etc. With a little studying, the plans make everything relatively clear.
The rivet callout for the rear spar is a little more complicated than anywhere in the empennage.
First off, I clamped all the parts together on the left spar and made sure all of the holes still lined up. I riveted W-707F first. For now, this piece only receives 6 rivets.
Only 6 rivets are squeezed on W-707F for now.
Next, W-707E went on using only 5 rivets.
Only 5 rivets are squeezed on W-707E for now. The rest will be installed during assembly with other pieces.
Finally, W-707D and G were riveted. Most of the holes on these two pieces are filled now, but you have to be careful to leave certain holes for later. Shop heads are on the aft side of the spar since good practice is to place the factory head on the thinner material.
W-707G and D have a few more rivets, but you still have to be careful to use the right size and leave certain holes open.
Once the left spar was assembled, I repeated the process on the right spar. Up next, I’ll hang the spars on my stands and start working on the ribs.
The rear spars are assembled...on to the ribs. Mmmmm...ribs!
Prepped and Primed Right Rear Spar (7/14/10)
Posted by Ethan Jacoby in Construction, Spars, Wings on July 15, 2010
1.0 Hours -
I had a softball game at 7:50 tonight, but managed to put another hour on the build-o-meter before heading off to the game. Working in the hot garage was almost like a warm-up anyway!
The last time I worked on the rear spars, I was having trouble understanding how to rivet W-707F to W-707A. The rivet call outs in the plans were fairly clear except for the outboard most row of rivets. This row will also attach one wing rib to the rear spar, and the outboard aileron bracket also covers it up. What I didn’t realize at first was that this row is the only row that uses countersunk rivets. If I would have realized that the other day, none of this would have been confusing. The aileron bracket is not attached using this row of rivets…it is attached by the row next to it and only covers up the outboard row. Since the aileron bracket needs to rest flush on W-707F, countersunk rivets must be used. With this straightened out in my head, I had to go back and dimple W-707A and F (left and right) appropriately and I’ll have to remember to dimple the outboard rib as well when the time comes.
I realized the left-most row of rivet holes needed to be dimpled after the pieces were primed...oh well, no damage done.
With my confusion out of the way, I went to work on the right W-707A. It is the only piece of the rear spars that I had not yet deburred and primed. The usual mantra ensued: deburr, scotchbrite, clean, prime.
Now that the right rear spar is primed, I can start assembly.
In case anyone is wondering, we lost the softball game after ending the first inning with a 6-0 lead.
Drilling and Prepping Rear Spar Components (7/11/10)
Posted by Ethan Jacoby in Construction, Spars, Wings on July 12, 2010
3.8 Hours -
I was able to spend a few hours working on the plane today. However, I’m at one of those stages where a few hours of work doesn’t equate to very much visual progress.
First off, I clamped all the spar components together. W-707E and W-707F are not match drilled, so they have to be aligned on and drilled using holes in the spar as a template. W-707F simply aligned with the outboard edge of the spar. However, W-707E, per the plans, had to be placed 50.75” from the outboard edge of the spar. For W-707E, a 1/4” off either direction could ruin your edge distance for the rivet line.
W-707F is aligned with the outboard edge of the spar and drilled using the spar as a guide.
W-707E is aligned 50.75" from the outboard edge of the spar and drilled using the spar as a guide.
Once all the spar components were clamped in place, I proceeded to drill all the holes to #30…holes on the spar flange that need to be dimpled now were drilled to #40.
The spar has a odd shape hole cut in it for the aileron pushrod. W-707E has to have a duplicate hole made in it. to do this, I just clamped W-707E to the spar and traced the outline of the hole to W-707E. Then, I used a step drill to remove the bulk of the cut-out. To finish the hole, I used a combination of Dremel attachments, files, and emery cloth. My holes in W-707E didn’t look as nice as those in the spar, but they are ok enough to move on.
Once W-707E is drilled and clamped, the spar is used as a template for marking the odd shaped cut-out that must be removed from W-707E.
The weird shaped hole in the spar is transfered to W-707E cutting.
I removed as much of the cut-out as I could with a step drill.
The rest of the hole was made with a combination of files, dremel tools, and emery cloth. Not perfect, but not bad either.
Next, I started to deburr all the holes that had just been drilled in the spar components. I managed to make it all the way through everything except the right spar (W-707A R)…that piece will have to wait for another day.
In addition to deburring, some of the holes on the W-707A spar flange and W-707E/F doublers have to be dimpled now since they can’t be reached after assembly. By dimpling now, I could easily reach everything with my pneumatic squeezer.
Finally, I primed all the pieces that were ready (everything except W-707A R).
As usual, more priming.
The left W-707A is primed...all that reamains to be primed is the right W-707A. Then, the rear spars can be assembled.
More Deburring of Rear Spar Components (7/5/10)
Posted by Ethan Jacoby in Construction, Spars, Wings on July 6, 2010
1.4 Hours -
I’m finding that working on the plane after returning from the gym is a good combination. I’m already sweaty, so the heat of the garage doesn’t bother me as much. Plus, I seem to be a bit more relaxed and can think a little more clearly. Or, its all mental, but whatever works!
First item on the to do list was to install the new band saw blade I bought at Home Depot. I have a Ryobi 9” saw, and my preferred blade for aluminum, so far, is a 18 TPI metal cutting blade made by Rigid.
Once the new blade was on and adjusted, I started to cut W-707G and W-707D. My old blade could no longer cut stock this thick (about 1/4”). Then new blade cut through the pieces as if they were paper. I should have changed the blade a month or two ago and saved myself some of the hassles I’ve had cutting. Lesson learned!
After cutting the parts to size, I began the always fun deburring process. To make sure the edges of W-707D and G line up, I clamped them together with clecos and deburred them as a unit. First off, I evened everything out using a vixen file. The vixen file quickly evened out and finished the edges.
To make sure the pieces ended up the same size, I clamped them together and filed them with a vixen file.
A before and after with the vixen file. Top: unfiled, rough edge. Bottom: filed, smooth edge.
Me and my trusty vixen file.
Next, I took the pieces apart so that I could round the edges using a Scotchbrite wheel. To do this, I used both my 6” wheel on the drill press, and a 2” wheel on a die-grinder. I also used some emery cloth to smooth areas that neither wheel could reach. Finally, I clamped the parts back together and did one final pass on the Scotchbrite to even up the edges again. By the way, Scotchbrite wheels de-skin knuckles as well as they deburr aluminum…use caution!
Me on the deburring wheel. My girlfriend calls this the "artistic shot."
Rear Spars Started (7/4/10)
Posted by Ethan Jacoby in Construction, Spars, Wings on July 5, 2010
1.2 Hours -
This morning, I started working on the rear wing spars. These are pretty simple structures consisting of a long piece of z-channel (W-707A L&R), which makes up the main structure of the spar, and four other pieces of aluminum that act as stiffeners/doublers (W-707D, W-707E, W-707F, W-707G).
All of the rear spar pieces laid out on the bench.
As usual, the first step is to deburr the edges of the parts. You can save all of the deburring for later if you want, but I’ve learned that those edges can be sharp. I’d rather deburr now and save my fingers! To deburr the stiffeners/doublers, I used the Scotchbrite wheel on my drill press. Due to the length of W-707A, I used a 2” Scotchbrite wheel on a die grinder to deburr its edges.
Since the various RV models often share parts, certain parts may have to be modified for one model, but used as is for another. This is the case for W-707D&G on the RV-7. If used on an RV-8, no modification is needed. However, on the RV-7 a tiny bit needs to be trimmed from the inboard ends. Van’s gives dimensions in the plans for the exact amount to be removed. My band saw blade has become so dull that it won’t cut thick aluminum stock, so, for now, I just marked the parts. Once I make a trip to the aviation isle at Home Depot, I’ll be able to finish the pieces.
A little modification of parts is often necessary since RV models share some parts. Here, parts of the rear wing spars have to be trimmed for use on a 7/7A.
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