Archive for category Flaps
Right Flap Final Prep Started (4/16/11)
Posted by Ethan Jacoby in Construction, Flaps, Wings on April 16, 2011
2.0 Hours -
Today was a full day of aviation and airplane building. I started off by going for a short flight in a Cessna 172. This was the first time that I had flown since January, and it was the first time I flew a C-172 in over 2 years! To top that off, I was flying with a new instructor out of an unfamiliar airport. The airport is Boerne Stage (5C1), and I chose to fly there because it is relatively close to our house and they also have the cheapest rental rates around…$88/hr wet for a C-172!
The first takeoff was ok, then we did a couple of steep turns…also ok, but my first landing attempts were horrible. On both attempts, I was way too high on final. After that, things started to get better. No more high approaches, and mainly smooth landings. I’ll still need a couple more flights before I feel comfortable as a solo pilot again!
When I returned home, I decided to do a little work on the RV project. I hadn’t worked on the plane for 10 days, and the right flap, clecoed together on my work bench, had been calling my name every time I went into the garage. All that is left to do on the right flap is to deburr, dimple/countersink, and rivet. Today, I made it through all the parts except the skins. However, it should only take me another hour to have the skins deburred and dimpled.
Surprise, surprise, another primer picture...I probably took an identical one for the left flap.
My workbench is a mess with spar parts and tools. I definitely need to do some cleaning/organizing once the right flap is finished.
With my benches a mess, the best place to store the flap skins is on the aft side of the wings.
Right Flap Drilled (4/6/11)
Posted by Ethan Jacoby in Construction, Flaps, Wings on April 6, 2011
1.7 Hours -
With as much fun as I had building the left flap, my enthusiasm for starting the right flap isn’t too high. However, I managed to force myself into the garage and get started. I wasn’t planning on doing much, but after finishing one part, I would decide to start the next…soon, the right flap was completely clecoed together and match/final drilled. Including drilling the hinge, I think the right flap took about half as long as the left did up to this stage. Of course, the real time-consuming stuff is yet to come. The right flap parts now need to be disassembled, deburred, dimpled, countersunk, primed, etc, before they can be put back together for good.
The right flap is final drilled and ready for disassembly and finishing.
A closer view of the inboard end of the right flap.
Left Flap Finished (4/5/11)
Posted by Ethan Jacoby in Construction, Flaps, Wings on April 5, 2011
1.3 Hours -
The left flap is finally finished and ready for mounting on the wing! All that I had left to do was to finish riveting the forward spar, so it was just a quick work session tonight.
After finishing the top side of the forward spar (these rivets were shot and bucked), I went back and re-did a couple of bad rivets. Then, I re-did them both again, because my second attempt was as pathetic as the first. Both of these rivets (the first and third from the inboard end) were giving me trouble due to reduced access for the bucking bar caused by the FL-706A angle. However, on the third attempt, I was happy enough with the shop heads to move on.
Once the rivets in the top side of the spar were set, I took the flap out of the stands and laid it on the bench upside down. I also weighed it down with a couple of cleco containers. With the other control surfaces, this method was used during final riveting to ensure straightness. I figured it should work here as well.
The bottom of the spar/hinge was the last area to get riveted. To make sure the flap stayed straight, I weighed it down on the table instead of working in the stand.
All of the rivets on the bottom side of the spar, which are also used to attach the hinge, could be reached with my pneumatic squeezer. With the squeezer, riveting is a breeze, so it took no time at all to finish the bottom side of the spar.
The last five rivets connect FL-706A & B, and they are easily squeezed.
The last thing that I did was to mark a line on the wing side of the hinge that is 3/16″ from the edge of the hinge. This is the minimum edge distance for drilling. When I’m ready to drill the flap to the wing, I just have to make sure I don’t go past this line. If I can’t align the flap without compromising edge distance, I’ll have to order a slightly wider hinge. Needing wider hinge seems to be a somewhat common occurrence among builders. Fortunately, if this happens to me, I won’t have to drill out the hinge on the flap side since it is only the width of the hinge that changes…not the size of the loops.
Now I get to repeat everything on the right flap. I hope I remembered all the little tricks I picked up!
The left flap is FINALLY finished...now I get to repeat it all on the right!
Left Flap Riveting Started (4/3/11)
Posted by Ethan Jacoby in Construction, Flaps, Wings on April 3, 2011
3.5 Hours -
I finally started riveting the left flap. After doing a lot of searching for the best way to set these rivets, which have very limited access, the method I found was to use my 3″ pneumatic squeezer yoke as a bucking bar. Since the yoke is thin and heavy, it should work. Ironically, I found this method on Chad Jensen’s build site. It’s ironic because Chad is the guy that I bought my squeezer from!
A tip from another builder led me to use a squeezer yoke as a bucking bar in the flap.
Before riveting, I cut a small strip of drawer liner and placed it inside the flap against the aft spar. This will protect the aft spar from the bucking bar, and give me a place to rest the bar while riveting some of the rivets and not have to worry about scratching anything. However, once I started riveting, I only made it through about 6 rivets before the stand holding the flaps broke. So, I had to take a short break to build a new stand. This time, I used plywood instead of a plank.
A strip of drawer liner helped me protect/cushion the aft spar during riveting.
A few rivets in, my stands broke and I had to build new ones. This time, I used 3/4" plywood instead of a plank.
Once I built the new stand and got back to riveting, everything went relatively smoothly. The squeezer yolk/bucking bar made access a bit easier. After finishing all of the rivets on the main structure of the flap, I clecoed the forward spar in place and used blind rivets to attach the ribs to the forward spar. On the inboard rib, I screwed up one blind rivet (I didn’t set it flush due to very limited access), and made the situation worse when I drilled it out. The hole was enlarged so I’ll have to find a slightly larger diameter rivet to use here.
After setting the blind rivets, I started riveting the top skin to the spar. Once again, I had to find the best bucking bar for the situation. One of my new bars has a slanted face that worked perfectly. However, I only made it through about half of the spar before deciding to head inside for dinner. Finishing the left flap should only take another hour or so.
This bucking bar worked well for the forward spar rivets thanks to its angled face. All of the duct tape is to protect the flap parts from scratches and dings.
Almost done with the left flap!
Left Flap Work…Again (3/30/11)
Posted by Ethan Jacoby in Construction, Flaps, Wings on March 30, 2011
1.5 Hours -
I’m now ready to either start riveting the left flap together or take it apart and figure out a better way to do things. Again, despite what Van’s says, the flaps are not the easiest control surfaces to build! On another note, sorry about my poor photography on this post. I think the various flap parts I had on the table were, sometimes, causing the flash to bounce around too much, filling some of the pictures with way to much reflected light. Unfortunately, I didn’t realize this until I was resizing the pictures in Photoshop, so what’s done is done!
To start off the evening, I finished dimpling the left flap skins. The top skin is a bit odd since it has a partially curved leading edge, and the trailing edge is bent and continues about a quarter of the way back to the leading edge where it mates with the bottom skin. Because of this shape, every dimpling tool in my arsenal had to be used.
Next, I clecoed the ribs to the bottom skin and squeezed the single rivet that attaches the 4 internal ribs to the aft spar. This has to be done now, otherwise there is no access.
The flap ribs must be riveted to the aft spar first, otherwise, you can't access them.
Another view of the rib to aft spar rivet.
Then, I assembled the flap with clecoes and placed it in the wood, v-brackets I built for assembly. At this point, the forward spar is removed from the structure in order to gain access to the inside of the flap for riveting.
With the spar removed, I decided to rivet the FL-706A angle to the inboard end of the spar now rather than wait. It attaches to the spar with 5 rivets, all of which can be squeezed, and it felt good to finally assemble something on the flap!
The FL-706A angle is riveted to the spar with five rivets. The three open holes will be used to attach the inboard rib with blind rivets.
Next, I removed the inboard rib from the flap assembly and riveted the FL-706B plate and nutplate to the rib. The plate and nutplate must be riveted before the rib is riveted to the flap, otherwise access is extremely limited.
The FL-706B plate and nutplate are also riveted to the inboard rib now while access is still available.
Another view of the inboard rib with FL-706B attached.
At this point, the flap is ready to be riveted together. I played around with various bucking bars for a bit to see how I will access the inside of the flap. I have big hands, so I was having trouble figuring out a way to access all of the rivets. One tip I have seen is to use a squeezer yoke as a bucking bar since they are heavy and thin. This may be my best option. The other thing I’m considering is to take the flap apart and rivet the ribs to the bottom skin while they are separate from the rest of the structure. Once this is done, I could cleco everything back together and have far fewer, difficult to reach rivets left to buck.
More Left Flap Work and Aileron Installation (3/27/11)
Posted by Ethan Jacoby in Ailerons, Construction, Flaps, Main Structure, Wings on March 27, 2011
4.0 Hours -
About half of my time in the garage today was spent deburring the left flap skins and dimpling anything I could reach with my squeezer. However, I got stuck on about 4 holes on the top skin. I can’t find any way to dimple the aft-most holes because the bend in the skin is so tight that nothing I have can get in their. So, as I thought about what to do, I moved on to other items including priming the FL-706A & B (these will be the only flap parts that get primed) and installing the ailerons on the wings.
On the ailerons, I decided to start by installing the bellcranks even though I don’t have any of the push tubes completed. To install these, I had to remove both bellcrank brackets and re-drill them to 1/4″. Apparently, the drill bit I used originally was slightly undersized and the AN4 bolt wouldn’t go through. I was going to have to remove at least the top bracket anyway, so removing both wasn’t such a big deal.
After re-drilling the brackets, I reinstalled the lower bracket, then slid the bellcrank bolt through the top bracket, bellcrank bushing, bellcrank and lower bracket. Before installing the bushing, I lubricated it with some Aeroshell 33. Van’s just says to use your preferred grease. Since I don’t have one, I decided on Aeroshell 33 since it advertises itself as and all-purpose airframe lubricant.
The aileron bellcranks were easy, but time-consuming to install since parts of the bracket have to be removed to insert the long bolt.
Next, I installed the ailerons on the wings. First, I had to make a spacer for the lower end of the inboard aileron bracket. This spacer was just a piece of tubing stock cut to the appropriate length. Actual installation of the ailerons was simple, but sliding all the washers into place is a bit of a pain. It was nice to see the ailerons in place. For some reason, they make the wings look more like wings!
The ailerons are attached to the inboard bracket using a spacer and several washers.
The aileron is attached to the outboard bracket using several washers and there isn't much room to work.
The outboard end of the wings with the ailerons installed.
Another view of the aileron on the right wing.
Left Flap Continued (3/26/11)
Posted by Ethan Jacoby in Construction, Flaps, Wings on March 26, 2011
3.3 Hours -
The second sentence on the flaps section of the instructions states, “The flaps are the easiest control surfaces on the RV-7/7A to build.” I’m going to have to strongly disagree with this statement. In fact, I would say that they are the most difficult. It’s not that they are complicated, but there is a fair amount of fabrication, and the instructions are the vaguest instructions thus far. Because of this, I had to take a few steps back today in order to complete a few things I missed (actually, I didn’t miss them, the plans just weren’t clear on when they needed to be done!).
I still needed to finish the fabrication on the FL-706A angle and the FL-706B plate. The angle needed five holes drilled in it and then it needed to be matched drilled to the spar.
I drilled 5 holes in the FL-706A angles per the plans prior to match drilling to the spar.
The rest of the holes in the FL-706A angle are drilled using either the spar or the FL-706B plate as a guide.
Once the angle was in place, I turned my attention to FL-706B. These plates need to have a slight bend put in them. The plans call for one to be bent up 6.3 degrees and the other down 6.3 degrees (this creates a left and a right piece). I’m not sure why they don’t say 6 or 6.5 degrees…who’s going to be able to get 6.3? Even with a digital level, like I’m using, it’s not that accurate. Even if the display reads 6.3, it’s not exactly 6.3. Anyway, I clamped each plate into my vice and used some wood scraps to gain leverage on the part. In the end, I had one bent to 6.0 degrees and the other to 6.2 degrees on my digital level. Once the plates are clamped to the rib/spar, I’ll be able to finesse them further if needed.
The FL-706B plates need a slight bend...the plans call for 6.3 degrees. This is my bending setup.
6.2 degrees on the digital level should be close enough. The other one came out to 6.0.
Next, I drilled the plate to the inboard rib and FL-706A angle. I had to do this with the spar and ribs clecoed to the bottom skin so that I would know the inboard rib was at the correct angle to the spar. The angle of the plate matched the rib perfectly. Once the plate was drilled to the rib, I enlarged the aft hole to 1/4″ for the AN4 bolt that will attach the flap to the actuator. I also drilled the holes for attaching the nutplate using the nutplate as the guide.
FL-706A & B are drilled to the inboard rib and spar.
The aft hole on FL-706B is enlarged to 1/4" for a nutplate.
Fabrication of the left flap is pretty much done now, so I disassembled everything and deburred the holes in all of the parts except for the skins. I also countersunk the bottom of the spar. The spar is countersunk to accept the dimples in the skin, and the hinge is left untouched.
The bottom side of the spar is countersunk to accept the dimples in the skin. The hinge isn't countersunk or dimpled, but I used it as a guide for the countersink cutter.
Next, I built a flap assembly jig to help with riveting the flap together. For this, I just screwed a couple of pieces of scrap wood together, traced the outline of one of the outer flap ribs, cut the v-shape out of both pieces simultaneously, and then attached each piece to a base. I was able to reuse my aileron assembly bases as the bases for the flap assembly jig. Although I’m calling it a jig, it is really nothing more than a stand for holding the flap in an optimal position for access during riveting.
I also made some v-brackets to hold the flaps during riveting. I screwed to pieces of wood together so that I could cut both sides at once.
The bases for my v-brackets are the stands I used for riveting the ailerons.
Finally, I wrapped up the day by removing the blue vinyl from the skins in order to prepare them for finishing.
The last thing I did for the day was to remove the blue vinyl from the skins in order to prepare them for deburring and edge finishing.
Left Flap Skins and Hinge (3/23/11)
Posted by Ethan Jacoby in Construction, Flaps, Wings on March 23, 2011
1.8 Hours -
The first thing I did this evening was redo the small shims that go between the interior flap ribs and the rear spar. The original ones were probably fine, but I wanted to make them just a bit bigger. Measuring the pieces took only a few minutes…cutting and finishing them was quick using the band saw and Scotchbrite wheel.
Next, I flipped the flap over and drilled the bottom skin to the ribs. Once the bottom skin was drilled, it was time to attach the hinge. Piano hinge is used to attach the flaps to the wings. The hinge runs the full length of the flap spar much like the hinge that was used to attach the trim tab to the elevator during empennage construction. To make sure I was keeping the hinge straight, I drew a line down the center of one section of the hinge. Once the hinge is clamped to the flap, I just have to make sure the line is visible through the holes in the skin/spar. As long as the line is centered in the holes, I know the hinge is straight.
I marked the middle of the hinge stock to aid with alignment on the flap.
The hinge clamped to the left flap. I cut it to length after it is drilled.
Here, my line is visible through the holes in the flap. As long as I can see that line, I know the hinge is straight.
After drilling the hinge to the flap, I clecoed on the top skin and drilled it to the rest of the structure. All that is left is to take everything apart, deburr and dimple the holes, and rivet everything back together. My plan is to finish the left flap, including mounting it to the wing, before I continue with the right flap. This way, I know my construction technique was correct before I move on to the other side.
The left flap with the hinge and top skin clecoed on.
Left Flap Work (3/21/11)
Posted by Ethan Jacoby in Construction, Flaps, Wings on March 21, 2011
0.8 Hours -
The FL-708 spacers needed a final touch before they were ready for the flaps, so I ventured into the garage for a quick work session after returning home from my real work. All that needed to be done was to drill a single hole in each spacer so that they can be clecoed to the inboard and outboard flap ribs. The second hole in the spacer is drilled using the skin/rib as a guide. After measuring for the location of the holes, center punching them, and finally drilling, I should have stopped for the day, but I pressed on (keep reading to see why I should have quit at this point).
I finished the FL-708 spacers by drilling one #40 hole in each spacer. The other hole will be drilled using the skin/rib as a guide. The top spacer is drilled while the bottom spacer has only been center punched.
Next, I located the appropriate ribs for the left flap and drilled them to the spar. The internal ribs are pre-punched with small holes, which momentarily confused me since the plans say that they need to be riveted to the spar with LP4-3 rivets. So far, if the hole needs to be final drilled to #30 or larger, Van’s has generally pre-punched it with the larger hole size. I scanned the plans a bit more before deciding that enlarging the holes to #30 was appropriate.
Once the skeleton was assembled, I clecoed on the bottom skin. Flap construction is a bit different from the other control surfaces because the rear spar is built into the bottom skin as a bend. The flaps take on a lot of force when they are extended, so I’m guessing using only ribs wouldn’t be strong enough and using a traditional rear spar would make the trailing edge to wide.
The left flap skeleton and bottom skin temporarily clecoed together.
The instructions are very clear that aft end of the interior flap ribs need to touch the bottom skin rear spar, but some of them won’t and will require shims to be made. I inspected my assembly and found that the gap between the rib and spar ranged from none to fairly sizeable. I decided that three of the ribs would require shims, and .025 aluminum would be sufficient for all of them.
Here's a composite of the aft ends of the four interior ribs on the left flap. They range from no gap, to a big gap with the shim already in place. I decided to shim all except for the one on the left.
I cut enough shims so that I would have them for the right flap as well. After sliding the shims into place, it was clear that they would fill the gaps, so I started drilling the ribs/shims to the rear spar. The aft end of the ribs are not pre-punched, so the hole in the rear spar is used as a guide for drilling both the shim and the rib. Once again, Van’s pre-punched the rear spar with a small hole that needed to be enlarged to #30.
Drilling the rear spar is where my problems arose and my work session ended. The first rib was easy since it didn’t require a shim. However, on the second one, the drill bit grabbed the shim and started spinning it. Not thinking, I had my finger in the way and the spinning shim was, essentially, a spinning blade that cut into my finger on two of its rotations. On first inspection, the cuts didn’t appear to be too bad, so I altered my technique and moved on to the next rib. About halfway through drilling, I felt something warm on my hand…blood was pouring out of my finger, down my hand, and on to the work bench. Being a dedicated aircraft builder, I wrapped my finger in a paper towel (heavy-duty shop paper towel of course), applied some duct tape, and continued working until all the ribs/shims were drilled. I then went inside to inspect the damage. The amount of blood was deceptive as the cuts weren’t too bad.
After bandaging my wounds, I briefly returned to the garage to inspect the shims. They are ok, but I may redo them and make them slightly larger. At least the second time around I will know to keep my fingers out-of-the-way!
Flaps Started (3/20/11)
Posted by Ethan Jacoby in Ailerons, Construction, Flaps, Main Structure, Wings on March 20, 2011
3.3 Hours -
At first, my plan for the day was to mount the ailerons on the wing. With this in mind, I started working on the aileron bellcranks. I drilled the holes in the bellcrank to the proper size for AN3 bolts. Then, I pulled out the brass bellcrank bushings and used a 1/4′ drill, chucked in my drill press, to open up the bushings for AN4 bolts. After doing this, I rethought my plan for mounting the ailerons and decided to switch to building the flaps. No real reason for this change.
I started the day by working on the aileron bellcranks. I got as far as drilling the bellcrank bushings to size, then decided it would be better to wait on the rest until I'm ready to install the ailerons on the wings.
My flap work for the day consisted of a lot of deburring and fabrication. By the end of the work session, I had everything made that is fabricated by the builder (not much), and I completed the edge finishing on all the parts except for the skins.
On to the flaps!
First up, I finished the edges of all the ribs. This includes four FL-704 exterior ribs and eight FL-705 interior ribs. These were finished using only my large Scotchbrite wheel mounted in the drill press.
Here's a pile of flap ribs after deburring their edges.
After the ribs, I needed a little break from deburring, so I fabricated the FL-708 spacers. These spacers will be placed at the bottom, aft of each of the exterior flap ribs to fill a gap between the skin and the rib. As usual, Van’s provides a full-scale drawing with detailed dimensions for parts that the builder fabricates. Since this part is nothing more than a small rectangle of .025 alclad, I didn’t have to rely on the drawing too heavily! To make the spacers, I cut them from scrap aluminum using my bandsaw, and then finished the edges on the Scotchbrite wheel.
The FL-708 spacers (2 per flap for a total of 4) had to be fabricated from scrap aluminum...fairly simple stuff.
Four FL-708 spacers ready for drilling.
Next, I deburred the edges of the FL-703 spars. The long edges were easy to finish using the large Scotchbrite wheel, but the small lightening holes are more of a pain. For these, I used a combination of tools including a swiveling edge deburr tool, small Scotchbrite wheel in a die grinder, and a maroon Scotchbrite pad. Fun stuff (not really)!
The flap spars after deburring...the lightening holes take a significant amount of time to deburr.
With the spars deburred, I moved on to the FL-706B plates. These plates are made from thick aluminum and they reinforce the area where the flap actuator mechanism attaches to the flap. Since these are made from thick stock, I first filed the edges with a vixen file to remove all the marks left from fabrication at the factory. Then, I ran them through the big Scotchbrite wheel to knock of the corners and polish the edges. These parts will be given a slight bend later on, so I went ahead and marked the bend line now. One will be bent up approximately 6 degrees and the other down 6 degrees in order to create a left and right part. The actual bending shouldn’t be difficult, but it’s going to have to wait for another day.
I deburred the FL-706B plates and marked were they are to be bent. One goes up 6 degrees, the other down 6 degrees.
The final thing I did today was to fabricate the FL-706A angles. These are used in combination with the FL-706B plates to reinforce the area of the flap where the actuator is attached. As with the FL-708 spacers, a detailed drawing with dimensions is provided, and it is up to the builder to cut these from supplied angle stock. Again, these are fairly simple parts. The angle stock is cut to the appropriate length. Then, the short side of the angle is cut down even further. Finally, the parts are deburred using a combination of a vixen file and Scotchbrite wheel.
The FL-706A angles have to be fabricated from this piece of stock angle.
As usual, Van's provides dimensions for parts that the builder fabricates. Here's the FL-706A drawing.
The FL-706A angles after cutting to size and deburring the edges.
With all of these parts prepped, it should be a relatively quick process to finish up the flaps. The only thing I’m not looking forward to is dealing with the flap hinges.
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