Archive for category Fuselage
Aft Fuselage Final-Drilled (2/20/12)
Posted by Ethan Jacoby in Aft Fuselage, Construction, Fuselage on February 20, 2012
2.0 Hours -
After two hours of work today, I finally finished drilling the aft fuselage…including the annoying tail section. In order to get the F-779 skin and side skins to line up, I ended up removing the F-779/F-711/F-712 assembly one more time. With the assembly removed, I drilled the last few holes in the J-channels using the side skins as a guide. With the J-channels now fully match drilled, at least I would be able to see through the holes in the F-779 skin.
Once I reassembled the tail section, the holes still didn’t line up perfectly, but I was able to coax them into position by clecoing every hole and getting a lot of help from an awl. Once everything was clecoed, I removed one cleco at a time to final-drill the holes. The very last hole on each side still didn’t want to line up very well, and I think the holes got a little oval. I will probably go back and drill these holes to #30 and use a 4- rivet. I may do this to a few more of the aft holes as well. The bigger drill will help make sure the holes are round, and the bigger rivet will only strengthen the structure.
It was a lot of work to get everything to line up in the aft-most section of the fuselage. I'm happy to have this done!
With the tail section finally drilled and clecoed, I proceeded with final-drilling the rest of the holes in the aft fuselage (except for the F-706 bulkhead). This was an easy enough task, but drilling the holes on the bottom of the fuselage wasn’t much fun! Of course, now that everything is drilled, the next step is to take it all apart for deburring and dimpling.
J-Channels Drilled (2/18/12)
Posted by Ethan Jacoby in Aft Fuselage, Construction, Fuselage on February 18, 2012
2.7 Hours -
My least favorite part of the airplane build, so far, is the aft-most two feet of the fuselage. It’s not that any of the construction techniques needed in this section are difficult, but the parts simply don’t fit together well. Up to this point, everything in the kit has fit together perfectly. However, it appears that I’m having the same issues as everyone else, so, build on!
Still not entirely happy with the fit of the F-711/F-712/F-779 assembly, I removed it from the aft fuselage, once more, and attempted to tweak the angle of the bulkhead flanges a bit more. I’ve taken this off so many times now that reinstalling it has become a bit easier. It still took me about 45 minutes from start to finish, and the fit still isn’t perfect, but it is much better than any of my previous attempts. Therefore, I’m calling it good.
The next step is to drill the J-channels to the skins. However, before doing that, I have to make sure the aft fuselage is straight. This is really overkill for the match-drilled kits, but it’s easy to check, so I figured why not!
To check for straightness, I hung two plumb-bobs off the aft fuselage. One was hung from the top of the F-706 bulkhead at the front of the aft fuselage, and the other was hung from the F-712 bulkhead at the rear. The tooling holes in the top and bottom of the bulkheads are on-center. If the string of the plumb-bob crosses both holes, on both bulkheads, the fuselage is free of twist.
The camera makes it look a little off, but the plumb-bob hung from the F-706 showed that the front of the aft fuselage is free of twist.
Another plumb-bob hung from the F-712 shows that the rear of the aft fuselage is free of twist.
Once I knew the aft fuselage was straight, I started drilling the J-channels to the side skins. I did one channel at a time, starting at the front and working back toward the aft end. The plans state to drill and cleco every fourth or fifth hole, making sure proper alignment of the J-channel alignment is kept, then go back and drill the rest of the holes…this is exactly what I did. This wasn’t very complicated or difficult, but it took quite a bit of time.
Drilling the four J-channels to the side skins was easy, but time-consuming.
Everything was going fine with the J-channels until I got to F-711 bulkhead on the lower J-channels. From this bulkhead aft, the holes between the F-779 skin and the side skins don’t line up perfectly. I think this is due to the slight bending of the F-779 skin I had to do to get the bulkheads to fit correctly. To fix it, I think the holes will align if I use a big clamp to squeeze the tail a bit. If that doesn’t work, I’ll likely enlarge the holes to #30 and use bigger rivets. However, I don’t want to mess with this area of the plane any more today.
The 6 or so aft-most holes are mis-aligned between the side skins and the F-779 skin. Fortunately, I have a couple of ideas for fixing this.
To wrap up the day, I drilled all of the bulkheads, except the F-711, to the side skins. After I figure out the aft hole alignment issue, I’ll still have drill the holes in the bottom skin of the aft fuselage.
More Aft Fuselage Work (2/17/12)
Posted by Ethan Jacoby in Aft Fuselage, Construction, Fuselage on February 17, 2012
1.7 Hours -
I received a couple of new toys in the mail, which gave me a good excuse to work on the plane a bit. The first new toy is an electric aileron trim kit. I finally decided that if the plane is going to have electric pitch trim, it should have electric, not manual, roll trim as well. Since I decided to go with electric trim for both axis, I took the plunge and bought some CS-8 stick grips from Tostenas well. I could have saved some money by purchasing cheaper grips and using rocker switches on the panel for trim operation, but I really like the idea of having a little more functionality on the stick. Plus, the Tosten grips look really cool! Now, I just have to figure out what to use all the buttons for. The hat switch will be trim, and the trigger will be my push-to-talk, but that still leaves me with 3 open buttons.
The Tosten grips are really nice! Now to figure out what to use all the buttons for.
Tosten grip from the side.
Tosten grip from the front.
Once I quite playing with my new toys and went into the garage, the first thing I did was to drill the F-712 bulkhead and the WD-409 tail spring mount for the two “keeper” rivets called for in the plans. With little information in the plans, I decided to drill the holes 1/2″ from the center of the bulkhead, and low enough to where I was sure they wouldn’t interfere with the bolts that will eventually be installed in this location.
The plans don't give much guidance on their location, but I drilled the two keep rivets in the F-711 bulkhead and WD-409.
Next, I decided to remove the F-710 bulkhead, as well as the F-711/F-712/F-779 assembly, from the aft fuse so I could re-work some of the bulkhead flanges a bit. My goal was to get the flanges to better match the angle of the side skins, resulting in a better fit for the bulkheads. After messing with these for a while, I reinstalled everything and re-checked the fit. The overall fit is better, but I’m still having trouble getting about 1/4 of the F-711 bulkhead to skin holes to line-up. The flanges still have some room for improvement in the area, so I’m probably going to remove this whole section one more time the next time I work on the plane.
I removed, adjusted, and re-installed the F-711/F-712/F-779 assembly. The fit is better, but not yet perfect.
The angle of the flanges on the F-711 and F-712 bulkhead matches the skin a bit better now, but I'm still having trouble with about 1/4 of the holes on the F-711.
The aft fuselage is completely clecoed. I'll check for "straightness" before drilling anything.
Aft Fuselage Clecoed (2/11/12)
Posted by Ethan Jacoby in Aft Fuselage, Construction, Fuselage on February 11, 2012
2.5 Hours -
I started off by trimming the ends of the J-channels. On the lower four J-channels, both ends require trimming. However, I’m still not sure on the upper two, so those will have to wait. The actual trimming was completed by drilling a hole in the bend on the channel, enlarging the hole to the desired radius with a step-drill, and then finishing the cut with a Dremel and cut-off disc.
Once the J-channels were finished, I slid them back into place on the aft fuselage assembly. I then when to work clecoing the F-706 bulkhead to the aft fuselage. This took a little time since the F-706 assembly is a little bulky, and it took a little brute force to get things to line up at times.
With the F-706 in place at the front, I turned my attention to the rear and slid the F-710 bulkhead into place. The plans say to put the F-710 in last, but it is obvious that it would be a real pain to get the bulkhead in after the tail assembly is in place. With the F-710 loosely in place, I next started trying to cleco the F-779/F-711/F-712 assembly to the rest of the aft fuselage. At first, I couldn’t get the assembly to fit, but I quickly realized that the J-channels were interfering with the F-712 bulkhead. To fix this, I had to remove the tail assembly and trim a little more off the ends of the J-channels.
Once the J-channels were trimmed a bit better, it still took a little work to get the tail assembly to fit into place, but, eventually, I got it. I was able to cleco everything in the tail section except for one side of the F-711 bulkhead. The flanges of the bulkhead aren’t bent quite right. So, I’ll have to remove this part and re-bend the flanges so that they better match the angle of the fuselage side skin. Hopefully, this will take care of my fit problem.
The aft fuselage seen from the F-706 bulkhead looking back toward the tail.
A side view of the aft fuselage. The upper J-channels are just sitting on the top for storage...that's not their actually positioning.
The tail of the aft fuselage. The tail assembly is a real pain to get clecoed!
The flanges of the F-711 bulkhead still need some work. I'll have to remove the bulkhead and bend the flanges to better match the angle of the skin.
Aft Fuselage Initial Assembly Started (2/9/12)
Posted by Ethan Jacoby in Aft Fuselage, Construction, Fuselage on February 9, 2012
2.0 Hours -
My plan was to just do a couple quick things in the garage, but that quickly turned into two hours or work. On the plus side, it’s starting to look like I have an airplane in my garage, a disassembled airplane, but an airplane none the less.
The first thing I did was to steal an idea from several other builders and make a cheap center-line marker for marking the J-channels. A couple of the tool vendors sell nice versions of this, but I don’t think I will use it enough to justify the cost. Instead, I just taped a popsicle stick and a piece of aluminum to a sharpie. The popsicle stick is pressed against the edge of the piece being marked, resulting in a nice center-line all the way down the long lengths of J-channel. Marking all 6 pieces of J-channel took a matter of minutes with this setup.
A popsicle stick, a piece of aluminum, and some tape is all it takes to make a cheap centerline marker.
The center lines aren't perfect, but they're good enough for positioning and drilling the J-channels.
Next, I grabbed the F-779/F-711/F-712/WD-409 assembly. I still wasn’t perfectly happy with the fit of skin and the cutout for the WD-409, so I took the assembly apart and widened the cutout a bit more. I also used my hand seamers to bend the skin a bit more (not much). Finally, I enlarged a rivet hole in the skin so that it would accept a socket. Once the plane is assembled, this hole will allow me to get a socket on the nut that holds the tail spring in the WD-409. I then reassembled the parts and was much happier with the overall fit.
As I read the next step in the plans, I was happy to find out that I would finally get to start putting some of my assemblies together. Unfortunately, I would need three of the larger skins, and they were all located at the bottom of my parts crate. So, I started moving parts from the crate to the bench or floor until I reached the big skins on the bottom. I pulled out the F-778 aft bottom skin and placed it across a couple sawhorses. I also pulled out the F-773 side skins and leaned them against the sawhorses. I then took a few more minutes to move all the parts back into the crate.
With the F-778 aft bottom skin sitting on the sawhorses, I clecoed the F-707 and F-708 bulkheads to the skin. Then, the bottom four pieces of J-channel were slid into place. After that, the F-773 side skins were clecoed to the bulkheads. Finally, I positioned the F-706 bulkhead so that I could see how the forward ends of the four lower J-channels needed to be trimmed. I then marked the J-channels for trimming and removed them from the structure.
The aft fuselage is starting to go together.
The picture is blurry, but with the side skins on, it's starting to look like an airplane.
It shouldn't be long before I can sit in it and make airplane noises!
At this point, I called it a night. Next, I’ll trim the J-channels, replace them in the structure, and cleco the F-706 bulkhead in place. I have to admit, seeing big structures come together is always fun!
Tail Spring Mount Work (2/5/12)
Posted by Ethan Jacoby in Aft Fuselage, Construction, Fuselage on February 5, 2012
4.0 Hours -
Today was another day where I spent a lot of time on the airplane, but didn’t seem to get much done. The instructions for the fuselage have become so vague, that I spend more time studying the plans or looking at other build sites on the internet, than I actually spend building.
I wanted to start by trimming the ends of all the J-channels. However, after looking at the plans and looking at the assembled bulkheads, I was having a hard time figuring out which ends get trimmed on which J-channels. So, for now, I decided to hold off on doing any trimming until after I start assembling the aft fuselage and can see exactly where the channels go. In the meantime, I used a piece of scrap J-channel to make a template for trimming the ends. I should be able to lay the template over the end of the J-channel and mark the trim pattern. This will save some time over measuring every single time.
I used a scrap piece of J-channel to make a guide for trimming the ends.
Next, I located the F-779 skin and started trying to cleco the F-711 and F-712 bulkheads to the skin. I say “trying” because this was a real pain. Pretty much every other build site I’ve looked at has a complaint or two about the fit of these pieces. My kit is no different. The bend in the skin doesn’t match the bulkheads very close at all, so I spent a lot of time trying to add a little more bend where needed, and messing with the bulkhead flanges to get the right angles on them. Eventually, I got to the “good enough for now” stage, but I may work on it some more or even add some shims. I’ll wait until the aft fuselage is assembled for the first time before I go too far on this though.
Once I got the F-779 skin to bulkhead fit reasonable, I took the assembly apart so that I could make the cutout on the skin for the tailwheel spring. I traced the cutout drawing from the plans, taped it to the bottom of the skin, and marked the area to be removed. I then used my Dremel to make the initial cut. I didn’t spend much time finishing the cut at this point, because it will likely have to be widened once I see how the tailwheel spring mount fits.
The F-779 tailcone skin needs to have a cutout made for the tailspring. I traced the template from the plans.
The rough cut for the tailwheel spring is finished, but this will probably need adjusting after I see how the tailspring mount fits.
Next, the WD-409 gets bolted to the F-711 bulkhead. The two open rivet holes in the bottom of the F-711 are used for the bolts, but the plans don’t mention anything about how to position the weldment on the bulkhead for match-drilling. Fortunately, Brad Oliver’s great website explained that the bolt holes needed to be positioned 12/32″ below the top of the weldment.
Once I knew the location, it was easy enough to mark both the weldment and the bulkhead. I drilled the first hole in the weldment to #30 while the weldment was on the bench. Then, I clecoed the weldment to the bulkhead, aligned some marks, clamped it down, and drilled the second hole using the holes in the bulkhead as the guide. I then gradually enlarged the holes until I hit 1/4″ for the AN4 bolts.
The WD-409 tailwheel mount is drilled to the F-711 bulkhead. The plans are pretty vague here!
The WD-409 to F-711 holes get enlarged to 1/4" for AN4 bolts.
After bolting the WD-409 in place, I re-clecoed the bulkheads to the skin to check the fit of the cutout. The cutout needed to be enlarged a bit, but I also couldn’t get the F-712 bulkhead to seat properly. After a lot of fidgeting and swearing, I finally realized that the “mouse hole” in the bottom of the F-712 wasn’t big enough and was interfering with the weld fillet on the WD-409. Once I realized this was the problem, it was easy to enlarge the hole and get everything to fit properly.
I had to do a little trimming of the cutout in the F-779 skin in order to get the tailwheel mount to fit.
With everything in place, the next step in the plans called for drilling two holes for “keeper rivets” in the F-712 bulkhead and the aft face of the WD-409. Again, there is no guidance in the plans for determining where to locate these holes. So, it was back to the internet for some researching. Eventually, I found the consensus is that close is good enough in this case, but to wait until after the aft fuselage is clecoed together. So, I’m calling it a day because I’ve had enough fun with the tailwheel for one day!
The F-711 and F-712 bulkheads sandwich the WD-409 tailwheel mount. Now I need to figure out how to drill the WD-409 to the F-712 bulkhead.
Longeron Bending Finished (2/4/12)
Posted by Ethan Jacoby in Construction, Fuselage, Longerons on February 4, 2012
1.1 Hours -
Today, I finished bending the main longerons. To make the downward bend, I simply clamped each longeron in my vise, measured the angle, pushed the forward end down a bit, and whacked the apex of the bend with a rubber mallet. The bend only needed to be 5.6 degrees (according to the plans), so it didn’t take long to get the right amount of bend. The hardest part of this was checking the bend against the fuselage skin. Since the longeron has a bend in it, and the skin does not, it was hard to hold the longeron in place against the skin. However, I think my bends are good enough, and they can always be adjusted a bit if needed.
The downward bend is supposed to be 5.6 degrees...close enough!
After the downward bends were done, I had to put 17 degrees of twist on the end of the longeron. Again, no subtlety is needed. You simply grab the end of the longeron with a crescent wrench and twist the appropriate direction. To get the 17 degrees of twist, you have to twist way past 17. The first longeron took me a few tries, but I got the second on my first attempt!
17 degrees of twist...
With the downward bend and twist in place, the longeron bending is complete. Assuming everything is correct, this wasn’t nearly as difficult as I was expecting it to be. I’m sure the longeron dies made the shallow curve easier to make, but I still don’t see why longeron bending receives so many complaints.
With the main longerons out-of-the-way, I located the J-channel stock. Six J-channels (two each of three different lengths) have to be cut from the provided stock. Cutting them to the correct length was easy, but I came to a roadblock when it was time to trim the end of each channel. The plans seem really vague on the dimensions for the trimming (unless I’m reading them wrong), so I decided to call it a day in order to do a little research.
I cut the J-channels to length, but I'm confused about how to trim the ends.
Aft Canopy Decks Drilled and Trimmed (1/29/12)
Posted by Ethan Jacoby in Construction, Fuselage, Longerons on January 29, 2012
2.5 Hours -
When I went back into the garage today, the first thing I did was to double-check the curve in the longerons against both the paper template and the F-721B aft canopy decks. Both longerons needed a little tweaking, but not much. In both cases, the longerons had too much curve. To reduce the curve, I used the paper template to see where the curve started to become too much. I then clamped the longeron in my vise just forward of the section that had too much curve, and pulled the aft end of the longeron a bit by hand. It only took me a couple of attempts to get both longerons close to perfect.
After the curve is finished, the plans call for the F-721B aft canopy decks to be drilled to the longerons. The canopy decks need to overhang the longerons by .032″ so that they make a flush surface with the fuselage skin. To mimic the skin, I clamped a scrap strip of .032″ aluminum to the vertical side of the longeron. I then positioned the canopy deck, keeping it flush with my aluminum shim, and started to back-drill the longeron through the F-721B.
The F-721B aft canopy decks overhang the longerons by .032" so they sit flush with the skin. A .032" piece of aluminum acts as a shim while the canopy decks are positioned and drilled.
I wasn’t sure of the best way to drill the canopy deck. Usually, I start at one end of the part and work my way to the other end, drilling and clecoing each hole along the way. However, with the curve in the longeron and F-721B needing to be perfectly aligned, I decided to drill the forward hole, check alignment, drill the aft hole, check alignment, drill the middle hole, and then start drilling the holes in between. Apparently this worked ok, because the canopy decks and the longerons and aligned exactly as they need to be.
The F-721B aft canopy decks have been drilled and clecoed to the longerons.
Once the canopy decks were drilled to the longerons, they had to be removed so that I could trim the aft end of the decks per plans. You have to pay attention here because there are two drawings detailing the trim dimensions. One has dimensions for slider and tip-up, and the other has some additional area that needs to be removed for the tip-up. As usual, the drawings are well labeled, and it really didn’t take much time to mark the decks for trimming.
To do the actual trimming of the F-721B decks, I made rough cuts with my bandsaw and Dremel. Then, I had to do a lot of filing/smoothing to get a descent finish. Files, emery cloth, Scotchbrite…you name it, I probably used it!
The aft end of the canopy gets a little trimming. The cutting was easy, but smoothing out slot wasn't much fun.
Now that the canopy decks are drilled/clecoed to the longerons, the next step is to put the downward bend and twist on the forward end of the longerons. More fun longeron bending!
Longerons Started (1/28/12)
Posted by Ethan Jacoby in Construction, Fuselage, Longerons on January 28, 2012
3.2 Hours -
No reasons to put it off any longer…it’s time to make some longerons!
The longerons are shipped as 16 foot lengths of aluminum angle stock. These pieces of stock must be cut to length and then bent to match the shape of the fuselage. Since these are such critical pieces, I wonder why the factor doesn’t form them, but I do realize that they would be much harder to ship if they were already bent. Oh well, many have been made before me, so it can’t be that bad!
To measure the correct length, I took a tip from several other builders and taped the end of a tape measure to the end of the longeron. Since the metal part of the tape measure end can move a bit, I taped it to the longeron at the one inch mark, and I’ll have to add an inch to the final measurement. The overall length of the longeron is supposed to be 173-7/16″, so I measured to 174-7/16″. After checking the measurement several times, with two different rulers, I cut the longerons using my Dremel with a cut-off disk.
Taping the tape measure to the longeron at the 1" mark seems to be the common method for measuring the longerons.
At least I remembered to add the inch to the other end. The plans call for cutting at 173-7/16" so I measured 174-7/16".
Since a left and a right longeron has to be made, I marked the angles for top, outside, left and right. The next step is to cut a notch out of the horizontal face of the longerons at the aft end. After the notch is cut, there’s no going back, so I made sure I had the longerons marked correctly for left vs. right. The plans, as usual, provide the correct measurements for the notch, and, once the longeron was marked, I made the notch using my Dremel, a few files, and some emery paper.
The aft end of the longerons get trimmed a bit. The flash obscured some of my lines, but you get the idea.
This could still use some smoothing, but here's the trimmed longeron.
Next, I marked the longerons for all the bend locations. This has to be done prior to making any bends since the dimensions provided in the plans are based on a straight piece of angle. The longerons were marked at 28-1/4″ for the downward bend, 38-7/16″ for the start of the shallow curve, and 69-9/32″ for the end of the curve. In addition, I also made marks every inch inside the section that gets curved so that I would know how far to more the longeron dies with each squeeze of the vise.
The longeron bend points are measured on the straight longerons, so all marking must be done before bending. Here's a mark for the downward bend.
The start of the shallow curve is marked. I also ticked off marks every inch, from the start to end of the bend, so that I will know how far to move my longeron dies.
The end of the shallow curve is marked.
Per the instructions that came with the longeron dies, I placed electrical tape on the outside of the vertical face of longeron to prevent the dies from scratching the angle stock. I then inserted the longeron into the dies at my first mark, squeezed the vise closed, moved the dies an inch aft, squeezed the vise…I repeated this, inch by inch, until the curve was complete.
Starting the bend using my longeron bending dies.
About 3/4 through the first bend. Opening and closing the vise is a bit of work, but I think this is easier than the Van's method.
To check the curve, I used both the template in the plans as well as the F-721B aft canopy decks. The bends weren’t perfect, but they were pretty close. A little tweaking and they should be done. I don’t know how much more difficult this would be without the dies, but the nice thing about the dies is that they keep the longerons from twisting as the bend is made. For me, the lack of twist makes them worth the $30 I paid.
The shallow curves are finished. They may still need a little tweaking to make them perfect, but they are pretty close as is.
Since the curves went so well, I decided to not press my luck and I called it quits for the night. I’ll still need to make the downward bend and twist on the forward end of the longerons before they can be called done.
Bulkheads Finished (1/22/12)
Posted by Ethan Jacoby in Bulkheads, Construction, Fuselage, Longerons on January 22, 2012
1.0 Hours -
With a Penguins hockey game and two NFL playoff games on TV today, I only planned for short work session. Priorities, right!
Since I had already primed my F-711 and F-712 bulkhead parts, all that was left was to rivet them. The F-711 needed the bulkhead halves, as well as the F-711C bars riveted together at this time. The F-711D angle won’t get riveted until later in assembly after the skins are on. All of the bulkhead rivets could be reached with the squeezer, so I was a happy camper.
The completed F-711 bulkhead. The F-711D angle doesn't get riveted until after the skins are on.
A side view of the F-711 bulkhead.
The F-712 bulkhead was even easier than the F-711. For the F-712, just the bulkhead halves are riveted together (it’s a bit more complicated if you’re building a tri-gear model). As with the F-711, the squeezer could reach everything, making my short work session that much easier.
The F-712 bulkhead is riveted together with flush rivets on the aft side.
A side view of the F-712 bulkhead.
With these two bulkheads done, all of the bulkheads are finished (for now), and it’s time to move on to something new. Unfortunately, the next step in the plans is to cut and bend the longerons. This seems to be an area where a lot of builders get stressed out, but end up with satisfactory results. To make this a bit easier (I hope), I bought some longeron bending dies off a Vansairforce.net member some time ago. The dies are milled out of a relatively hefty chunk of aluminum, and the idea is to squeeze the longeron in the dies using a vise to make the gentle bend. I’m sure it will be a fun process.
Up next is longeron bending. I bought these dies a long time ago to assist with making the shallow curve.
The longeron dies bend the longerons by squeezing the dies together in a vise.
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