Dimpled the New #40 holes in the LE Skin and Subskin, Fitted Nutplates on Subskin

Last night it snowed and got cold, so I did not do much on the airplane except make plans for what I would do today. The next step was to dimple the new #40 holes surrounding the removable section in both the outer LE skin and the subskin. I used my C-Frame tool for most of the subskin holes, and the pneumatic squeezer for the rest of them. Then I was able to use the squeezer on many of the #40 holes in the outer LE skin, but there are still several that will require me to use the C-Frame tool to reach those. I have a little too much clutter on the bench and it was starting to get cold again, so I called it quits for tonight at that point.

I did, however, cleco the K1100-8 nut plates onto the subskin so that could check the fit and position. I used a trick that I learned while fitting the fuel tank, where you can use a #30 clecoe through the #30 holes I drilled for each screw location, and the clecoe will just fit through the hole in the K1100 nutplate and secure it to the skin so that you can drill out the #40 holes for each of the two rivets used to attach the nutplate to the skin. I put each cleco on  the inside of the subskin through each nut plate on the outer surface and adjusted the position of each one to check the initial fit and alignment. Here are the pics:

I'll need to clear off the bench and dimple table so I can take the LE skin and finish the remaining dimples on the perimeter skin #40 holes for the rivets, then drill the nut plate #40 rivet attach holes (2 per nut plate) in the subskin and deburr them, then figure out if I am going to dimple or countersink those #40 rivet attach holes for the nut plates, and proceed with that decision. Then comes cutting the metal out of the LE skin, making the edges nice and straight and smooth (except for the rounded 1/2 inch radiused corners), making the file folder template, marking screw hole locations on the new file folder template, fabricating the new removable section of the skin from .025 2024-T3 alclad aluminum-same as the LE skin (will probably make several "blanks" for this), match drill the #30 screw holes in the subskin and the removable section up to #19 for the #8 screws, deburring those holes, dimpling them for a #8 AN509-8R8 screw, and riveting the nut plates to the underside of the subskin. And then, after all that is done, I finally get to re-assemble and rivet all the LE parts together, and mount that damn thing permanently to the Left wing. 

Yup, I can't lie, I'm just about out of patience with all the LE work I've had to do for this mod, but the truth is, this is just the beginning. I still have other fabrication work to do, not to mention a repeat of everything I have done up to this point for the right wing LE. But at least the work that remains to be done after the major metal work is finished will be the "fun" part of the reason why I started this mod in the first place. The delays resulting from all the "unknowns" when I started this mod will not exist for the right wing, since I supposedly now know how to do everything and the order in which to do it. And for the right wing LE I will not incur the delays that were caused by the stupid pre-cut access panel in the bottom of the left wing LE skin either. So things should go a bit quicker for the right wing LE mod - I hope!

Marked and Drilled Corner Rivet Holes, Removed and Disassembled the LE and Deburred the Holes

I was really stressing over the position of the nut plate screw holes, and then, after all the measuring, marking, research, and second guessing everything, I suddenly realized something. The removable section of the skin is not really going to be all that "stressed" when compared to the rest of the outer skin. the subskin underneath is what is designed to handle the loads imposed over that portion of the LE. The removable section is just going to be a curved piece of aluminum that basically form fits over the subskin. There will still be some loads imposed by tension and compression due to aerodynamic forces of the air flowing over that section of the LE, and these loads will fluctuate based on the G-loading that is placed on the wing curing certain maneuvers, but again, the subskin is what is going to absorb the vast majority of these loads.

Because of this, I really do not need to fret so much over the location of the screw holes. That said, I had settled on 3 along each side and 4 along the rear edge to ensure that everything is held down firmly so that the removable section still aligns with the rest of the LE skin when it is screwed in place.

From my previous post, I also knew that I had to reposition the rear corner screw hole so that it was not placed directly in each corner, but placed on either side of the corner. One other thing that was causing me pain was that I was trying to prevent additional stress points by maintaining the existing rivet pattern as much as possible. As such, I was trying to maintain a line of screw holes along each side that would align the screw holes I had already drilled for the nutplates that will attach the fuel tank skin to the LE skin when the two sections are joined together. While this would hve almost worked well for the bottom side of the LE, this was not going to work all that well on the tops side of the LE, since the screw hole patterns differ just a bit on the top and bottom sides of the LE.So I decided to use the most-forward screw hole of the joiner plate area to align the most forward nut plates of the removable section as a starting point, and I chose to move the rear-most nutplate center hole 3/8 of an inch forward from the corners where the nutplate lines from the sides and the rear intersect each other. Then I decided to move the rear-most corner screw hole locations inboard about 3/4 of an inch from that same intersecting corner. This created the desired effect of offsetting the rear and side nut plates in each corner so that the screw holes would be on either side of the actual corner, but close enough that they should lock down the corners of the removable section with no problem.

Here is a close up one of the corners after measuring and drawing the approximate location of the nutplate by positioning it over the mark for the hole and tracing the outline of the nut plate so you can see what I am rambling about.

As you can see this provides plenty of clearance between each nut plate. Do  not get confused by the drawing of the side nut plate where the end appears to be right over the corner again. You have to remember that the nut plates will actually be installed on the inside of the subskin to accept the screws from the outer skin. They are drawn here so that I know how they will be oriented on the subskin when I install them.

The next thing to resolve was the spacing between each of the nutplates along each side  and the rear of the removable section on both top and bottom of the LE. As I previously mentioned, for the sides I chose the location for the most forward and most rearward nut plates, and then I more or less decided to split the difference of the distance between each of those locations for the location of the nutplate in the middle.

For the rear-most nutplates, after setting the two corner ones 3/4 of an inch inward from the intersection of the two nut plate lines, I then used a distance of 2 inches from each rear corner nutplate hole to position the next two inboard rear nut plates, and that left whatever distance in the middle, which was about 1 5/8 inches or so between those two nut plates. These distances are within the same distances where other similar nutplates are installed on the plane, so I feel pretty comfortable with the locations that I came up with. 

here is the pic that shows how I aligned the forward-most nut plate holes with the existing holes in the joiner plate:

And here is a shot of the spacing between the rear-most nut plates, flipped 90 degrees the wrong way for some stupid reason:

Next is a shot of how the perimeter rivet holes for the skin and the nutplate screw hole locations looked after they were drilled with a #40 drill bit for starters . I once again used a center punch to mark each hole, and manually turned the #40 drill bit to start each hole before finishing it with the drill under its own power:

After all the perimeter and nut plate holes were drilled to #40, I then switched to a #30 drill bit to enlarge the holes for the nut plates, since the screw holes ultimately need to be drilled to #19 to accept the #8 screw. Here is a shot showing the clecoes in each of the enlarged holes for each nut plate. Unfortunately it came out blurry for some reason and I could not correct it.

Tonight I had made my decision about the gap in the corner for the outer perimeter rivets. I decided to do exactly as I stated in my previous post where I would add one more rivet to each corner but back it up just a bit so that the edge distance was consistent with each rivet on either side. SO I drew a line to bisect the 5/16 x 5/16 square that includes the rear-most corner, and then I took a ruler and measured along that line, and used the edge of the curved corner of the removable section that intersects with that line to measure another 5/16ths of an inch from that point outward, and marked that location for the rivet hole. The net affect of this is that it provides a rivet line with the same rounded contour of the removable skin, which is something I have also seen done in other areas of the build.

Here is the pic after the new corner holes were drilled to fill the gap:

And here is the entre bottom section with all the holes drilled and clecoed. From this you can start to get a better idea of what I am trying to do:

And another blurry one of the top side of the LE

With those holes done I was ALMOST ready to go ahead and enlarge the nutplate screw holes to their final size using a #19 drill bit. It was a good thing that I decided not to do that just yet. Just as has happened to me about a million times in the past, I started to think about the next steps after this was all done, and that major next step is to disassemble the LE and subskin and finally cut out the LE skin along the cut line marks and clean up the edges so they will accept the .025 removable skin that I would still need to fabricate. As  I thought through this process it dawned on me that I would still need to figure out how to mark and drill the same screw holes in the new part. Unfortunately it looked like I was going to need to try to do this from the inside of the subskin, because the new removable skin would have to be fabricated from a new piece of aluminum, since the skin on the LE would be cut away and not really viable any longer - or so I thought. 

Then, after thinking about it today, I realized that I can resort to a trick I have used before, by taking a file folder and cutting it to size to match the dimensions of the cutout section of the LE after I finish trimming it away. Then I can also use either the cut out section of the outer LE skin, or even the subskin holes to locate and drill the nutplate hole locations in the new file folder template. Then I can drill them out on the template and use it to outline the new removable section on a piece of .025 2024-T3 aluminum, match drill at least the first set of nut plate holes on the bottom side to start, and begin the process of form fitting the new part to the LE by attaching the bottom and wrapping it around the front of the LE to ensure that it is tight against the subskin, attaching the screws as I go.

SO, I can use the file folder template to ensure that I put the holes in the correct location on the new part that I must fabricate. I may have mentioned before that this part of the process is very similar to what one does when they place a landing light in the outboard section of the front of the LE. The only real difference is that the templates from most landing light kits for RVs are already created and so you just have to use the marks on the template that is provided. IN my case I am te one that has to create the entire template - just oodles and oodles of fun.

So the hole point of this ramble is that I should NOT enlarge the nutplate holes any further until the LE skin section is removed, and new part is fabricated so that I can match drill the removeable section and the subskin at the same time when I am finally ready to do that. SO those holes will remain sized to #30.

SO the next steps were to remove the LE assembly from the wing, remove the clecoes attaching the subskin, and debur all the new holes, and then dimple the outer perimeter rivet holes in the subskin and the outer LE skin. Then I will be ready to cut out the section that is to be replaced by the removable skin. Frankly, after all this time, I cannot believe that I am even talking about this. Of course the sad part is that I have all of this same thing to do on the right wing, and the thought of that is a bit daunting right now, knowing how long  it has taken me to do this on the left wing. 

Anyway, some pics after the LE was removed and the holes were deburred:

And finally the bottom and top side of the subskin after it was removed from the LE and the new holes were deburred. At least the hole placement for everything seems to have come out pretty nice. Now I just have to hope that I do not screw up cutting the section out of the LE skin!

Marked and Drilled the Remaining LE Skin Rivets for the LE Mod

It was last March when I had finally managed enough courage to mark and drill the additional inboard and outboard rivet holes that will secure the edges of the LE skin next to each rib flange. I left off at the point where I needed to determine the number of rivet holes to make and drill for rear-most rivet holes on the top and bottom sides of the LE.

I specifically left off with a bit of a dilemma, because I was not sure about the rear rivet hole placement in the corner. If I used the marks from the lines I had drawn for the rivet holes, then the rivet pitch (distance between rivets) between the corner rear rivet hole and the first edge rivet along the edge near the same corner was a little bit wider than it is supposed to be when setting a section of multiple lines or rows of rivets next to each other.

SO I made a decision to at least mark and drill rear corner rivets, realizing that if I needed to later I could always add one more rivet between that one and one along the side to fill the gap. Again, the goal here is to prevent having to reassemble and disassemble the entire LE yet again for a couple of lousy rivet holes. I want all the holes to be marked and drilled so that I only have to disassemble the LE one last time. It's time to finish this beast once and for all.

Step one for locating the rear-most rivet holes was to use my rivet fan by drilling the four marked rear corners (2 corners each for the top and bottom side of the LE skin) with a #40 drill, and then clecoing the edges of the fan to each corner hole. I started with the bottom of the LE because it is flatter than the top side and a bit easier to work with.

With both corners of the fan clecoed in place, I then took a #40 drill bit and manually turned it inside each of the holes of the now equally-spaced rivet fan to mark and start the drill bit in each of the holes to prevent the drill bit from slipping off target. Once that was done I removed the rivet fan to view my handy work:

Then  was able to finish drilling each of the new holes on the rear side. This next pic shows the left side corner and the amount of space between the rear corner rivet and the first side rivet, which is at least 7/8 of an inch I think. it also shows the intersecting lines where I could place one more rivet in between these two to fill the gap. The problem with using that mark is that it creates a situation where that rivet's edge distance to the curve of the removable skin it right on the allowed limit, and so if I do add another rivet to this location I will probably set it back from the corner just a bit to present more of a slightly rounded rivet pattern around each corner, which would match the contour of the removeable section of the skin. And of course it also shows the rear rivet holes all clecoed together.

 Here is another closeup of the other corner on the top skin. I should also note here that the original plan was to use the same distance between rivets to adhere to the same standard practices for making patches to LE surfaces by matching the same rivet spacing used where the LE skin attaches to the main wing spar, but I felt that using the rivet fan to locate the holes also just about matched this same spacing, and it made it much easier to ensure that I would have a row of equally spaced rivets along that line.

Working on the curved surfaces always has many challenges, and frankly I have found this to be the most difficult aspect of the build so far, especially as it pertains to this LE mod that I am doing. Here is  a much better shot of how I positioned the rivet fan on the top side of the LE skin, which of course is the most curved side.

And the full row of rear rivet holes drilled and clecoed on the bottom side:

With all the LE skin to subskin rivet holes marked and drilled around the perimeter of the removable skin section, now it was time to determine what screw size nut plate size, the number of each along each side and rear of the removeable section, and the spacing in between each one. This was the most frustrating part of the mod so far, because I am unable to find any written source of info whatsoever that contains a formula or rule of thumb to use to determine how many screws or bolts need to be used in a certain area. So I contacted my Technical counselor and he consulted with a certified A&P mechanic. Basically I was sited the same rules that are established for rivet spacing, so I did not find this to be particularly helpful. I know that aircraft screws and bolts each have very specific ratings in terms of tensil, shear, and torsion ratings, and each nut plate also has ratings for this, but the one missing link to all of this is that I do not know how much of these forces are being applied to the areas where they will be used on the LE. 

So my next best method was to look at several areas of the airplane where Van's is applying similar screws and nutplates, and copy the spacing as much as possible. I plan to use K1100-8 nut plates with AN509-8R8 screws to attach the removeable section. I noticed that in various areas of the kit Van's uses spacing for these nutplates and screws that is anywhere from 1 7/8 inches to 2.5 inches. Based on on that, I set out to determine how many nut plates and screws need to be along each inboard and outboard top edge, and how many should be applied to the rear edge. this next pic was a first attempt at laying these up, but later on this changed a bit, after my tech counselor confirmed a suspicion that I had that you should not try to attach nut plates or screws directly on a corner of any part. 

This is because the corners of anything are where the largest stress concentrations tend to occur, and so if you want things to start cracking just start putting fasteners directly on corners of various parts. Instead, you need to offset the fasteners so that they are on either side of the corner. IN the next post I'll show the corrected/new layup for the nut plates on both the top and bottom sides of the LE. There are about a million measurements involved in all this, which is also why I will address all that in a new, separate post. Bottom line is that I think I now have the layout determined for the screw holes on the top and bottom of the LE, and it amounts to about 20 of them (10 on the bottom and 10 on the top. The screw holes have to be drilled before I disassemble the LE for the last time, so that I can then drill the corresponding holes for the rivets that attach each nut plate to the subskin. I plan to drill these holes to #30 first, and then to #19. Once the LE is disassembled I will be able to finish drilling and sizing all the screw holes in the subskin, dimple them,  and FINALLY cut out the section of the LE skin. Almost there.....

And one last pic of the rivet fan on the top side of the LE. Notice how it is positioned differently that how it was on the bottom side. this is because of the difference in flatness on the bottom vs. the top of the LE:

Built a second LE/Fuel Tank Cradle

I have been mentioning the need to build a second LE cradle for quite some time now, and last weekend I finally got around to actually doing it. It took me about 3.5 hours total to do it, as I had to take measurement of the existing one all over again, find the wood which I already new I had laying around, and cut, clamp, drill, and screw it all together. It turned out looking just like the other one, except that the cutouts are little tighter and better defined than the first one. This will allow me to work on a LE and a fuel tank, or two LEs or fuel tanks at the same time.
Here are the pics:

It took a saber saw, jig saw, saw horses, electric drill and screw driver, clamps, that same 3/4 x 1/8th inch vinyl weather stripping that  used on the other one, and a sanding drum on a drill for final shaping and sizing,and a tape measure to get it all done. Now I have two of them and this makes working the LE and tank assemblies much more efficient.

Fuselage damage from shipping?

About 2 days after the fuselage arrived, I started doing the inventory of all the parts, and finding places to put everything by rearranging my shelves by consolidating my remaining wing parts together to make room for all the new fuselage parts. I also started a much more thorough review the of the entire fuselage to look for any signs of damage. Unfortunately I did find a few things with the firewall that concerned me. the first was several splatters of something that dripped on my firewall that does not want to come off.

And then I found this in the bottom corner:

Obviously something had pushed on the bottom front corner of the firewall, and this in turn caused a crease up above where the bottom support angle for the floor support was located. It only creased the firewall in that area, so it was not cracked, but it causes me some concern because this area may tend to fatigue sooner than it should as a result of this. I called Vans and sent multiple pics and they ended up saying that it was "cosmetic" and not a concern. I have an email from them just in case this pans out differently. There is really no way for me to straighten any of this, and I might end up making it worse if I were to even try. I was disappointed, because just about everything else on the new fuse looks absolutely fantastic. 

When you have done this long enough, you come to realize that shipping damage is fact of life. The thing you must evaluate is something may turn into a life threatening situation for you or your passengers. Vans pointed out that the crease and the dent are in an rea that I basically a void where nothing much is going on except to provide a frame for the outer skin to wrap around the side and underneath to make up the bottom of the fuselage skin. All of the actual support structure begins just above this area, where the bottom and side angles create the structure that supports the weldments for each of the 4 engine mount bolts that hold the engine mount to the firewall. SO as long as this damage confines itself to the area it is located in now, there are no problems, I will however need to keep watching this, because if any cracking starts to form that will migrate to the upper areas of the firewall or the rivets in this area, then I have an issue that must be dealt with.

Here is another area I found, which looked like a crack in the weldment for the cross member. Vans told me that sometimes the powder coat surface will show some signs of surface cracking, but that's all that this is. They told me to take light sand paper and sand own the area to see if the crack disappears, or if it truly goes all the way to the metal. IN my case, the crack disappeared, so that was a relief. 

There was this "galling" of the landing gear in certain areas as shown below. Vans told me that this is common and is a result of sand blasting that is performed in this area of the metal for a number of reasons. It just looked strange under the powder coat. SO this one I have to take their word for it. My take on this is that as long as I treat the plane properly and do not subject anything to super hard or out of control landings, then the gear should be just fine.

And finally some pics of everything put away on shelves, including the very large curved top rear outer skin:

Pics of the QB Fuselage arrival on 9-22-18

As promised, here is a picture sequence of the arrival of my QB RV-8 fuselage. Basically what came in the tuck was the fuselage in about 75% completed state, a small box of remaining parts to assemble, and the Van's stock spring steel landing gear. A lot of builders are opting for aluminum landing gear made by a company called Grove, mostly because they seem to provide similar service but are about 20 lbs lighter than the stock gear. For now I am OK with the stock gear since most of my mission for the airplane consists of transporting only me, myself, and I where I want to go. Lots of powder coated parts for the rudder pedals and control stick linkage, etc., as well as parts for the seat floors, upper fuse skins and bulkheads, seats and seat backs, and baggage area parts.

Step 1, the custom truck arrives. The trash cans on the right side had to be placed in front of my house to prevent others from taking up parking space. I live across from school property with baseball, football, and soccer fields, and the fall is very busy with little league games being played on these fields across the street. SO naturally cars like to park along the sidewalk in front of my house. Well, today I needed the space for the truck, so I had to take precautions by tying up some orange tape between the two cans and setting them out in the street to keep others from taking up the space for the truck. When the truck arrived, the cans were placed on the yard on the right.

Next, the doors were opened, exposing the aft side of my fuselage on the bottom, and another RV-7 fuselage on top and further inboard in the trailer. The white scaffolding on top is part of the custom crane boom that allows one to lift the fuselage completely out of the trailer without the need for a forklift.

We had to move mu fuse out from under the RV-7 fuse a bit to allow the block and tackle assembly to be placed bear the Center of gravity of the fuselage, so that when it is lifted it tends to balance on the crane without being to tail or nose heavy. Funny, W&B for this was just as important as it is when you are flying. It was interesting to see where the balance point of the 16 foot long fuselage. When is it all finished, with an engine and the tail section installed, it will be about 21 feet long. The balanced point ended up being just forward of the steel seat back support cross member that separates the front and back seat passenger compartments. The front straps from the boom assembly were strapped around two plywood extensions  that run through the center section wing spar where the wings will eventually attach to the fuselage. The rear strap was wrapped underneath the rear of the main cabin and attached to the boom. then the crane hook was attached to the assembly  and it was time to lift it up and out of the trailer.

 Chapter member Scott Barkley was there to help me with the off load. The gentleman above is the truck driver. That's about all it took - the three of us - to off load the whole thing. It only took about 15 minutes or so. Next the crane boom is extended and the block assembly is being prepared.

Next, Scott is guiding the tail as the crane lifts the fuse and starts walking out of the trailer doors. Mike Rettig loaned me his specialized cart that he built to support his tail section of his RV-10. Turns out that it supports my entire RV-8 fuselage quite nicely as well. Thanks Mike!!!!!!!

And here is the boom assembly after having been moved out onto the extensions:

And finally it was lowered onto the dolly and the crane was disconnected. Now all we had to do was wheel it up to the garage. Worked like a charm with no issues whatsoever.

Scott Barkley after a job well done! Many thanks Scott for your assistance with this. 

And the next series of pics is where the unpacking begins. You would not believe the amount of packing paper that was stuffed into the fuselage, not to mention how everything was packed inside the fuse as well as inside the additional parts box. It begins with the push/pull tube for the elevator and the hinge material for the cowling that will be attached after I get the finishing kit. With all the trials and tribulations I mentioned in my previous post, I will say that Vans is definitely master at figuring out how to pack things in small spaces. Enjoy the sequence:

And finally the contents of the parts box. It also comes with a large box of hardware, and two trashcans full of packing paper!