More VS riveting pics

This is not the best pic, but if you look closely at the bottom you will see some flush rivets (appears as though there are no rivets at all) on the spar, and then you see the shop heads from the remaining AN470 universal head rivets. I bucked every single one of these rivets. I find that the spars and ribs are relatively easy to rivet together. Putting the skin on is a different story.

This pic shows the otherside with shop heads of the flush rivets. Flush rivets are installed on the bottom part of the rear spar because this must sit flush against the very last bulkhead of the fuselage where it is bolted into place during the final assembly of the tail. The round headed rivets are used for the remainder of the rear spar since they do not interfere with the fuselage. I had to drill out and replace one of the flush rivets for one of the hinges shown above. For some reason it was the only rivet that slipped out of the hole on me while I was riveting it into place. My attempt to continue to push it back into place was not very successful, and it resulted in a much wider factory head than it started with, and I over-drove the rivet on the other side so the shop head was not formed correctly either.

I managed to get it drilled out without messing up the spar, and replaced it with a much better looking flush rivet. I am feeling much more comfortable with the rivet gun, and I am now much less intimidated when driving the 1/8 inch diameter rivets. They are still very difficult to drill out, however, so I prefer to try to set these rivets correctly the first time.

178 hours Riveting the VS Rear Spar

Finally pounding rivets again on the Rear Spar of the Vertical Stabilizer. Here it is clamped to the edge of the work bench with hinges and reinforcing plate riveted together. Click on the pic to see a larger one with more detail. The green frog tape covers the holes where the ribs from the rest of the frame will attach to the rear spar. You can't put rivets in these holes yet, so the instructions wisely tell you to put tape over them so you don't accidentally rivet them by mistake.

For some reason I continue to have a problem setting good rivets where the hinges are located. Good news is that I only have to drill out about 5 rivets on this assembly and re-do them. A significant improvement from my last riveting adventure. It felt good to pick up the bucking bar and the rivet gun again. It has been way too long.

174.5 hours VS frame primed

Need a little more light when you prime? Just add a few Xmas lights in the background! Here is my priming setup once again, with the wire drawn across the garage, parts hung, and the 1x2 collapsable frame supporting my floodlights. Oh yeah, and my cars parked precariously close to the whole operation - not recommended when working with acid etching primer products. Luckily I kept all the primer on the airplane parts.

A much better "first run" working with the primer this time. The trick is definitely to mix the crap out of the primer and the reducer to ensure that it has the consistency of skim milk, so it will run off the end of my mixing stick for a second or two. You don't wait to start priming after mixing this stuff like you might do with epoxy-based primers. You just pour it in the cup and go.

Here are all the VS frame parts all primed and ready to be riveted. I have also masked the inside of my VS skin and will use the 7220 self etch primer in the can to prime the parts of the interior skin where the flanges of the spars and the ribs will attach to it, just as I did for the HS. I expect to have a completed VS and a partially completed rudder by the end of this weekend.

172 hours - Cleaning and Priming the VS parts

Finally got the skeleton of the VS primed tonight. I'll add pics tomorrow. I used the same process as as I did for the HS - hang the parts, prep the primer and the spray gun, prime the parts, then wash, rinse, and repeat. The amount of dirt and grime that comes off the parts when wiped down with a microfiber cloth and acetone still amazes me. You have to keep cleaning the part until all that grime no longer shows up on the cloth, to ensure that the primer will adhere correctly and will not come off. Full respirator gear is also required for the acid etching primer that I am continuing to use. As long as it is mixed correctly it seems to go on fairly well.

Next is the masking of the inside of the VS skin and spraying of the 7220 etching primer where the frame will contact the skin when everything is riveted in place. Again, it's the same process I used for the HS. Then it's finally "pounding rivet" time again! The goal this time will be to keep from marring the skin up so much and to avoid denting the skin like I did last time when I started riveting the HS.

The completion of the rudder assembly will follow soon after, and then the right and left elevators. I'm really itching to get started on the wings!

Bending brake for the trailing edge of the control surfaces

Warning! Anyone that is building an RV7 or different model of RV will be performing a different procedure to complete the Rudder trailing edge. This is because the RV7 uses a two piece skin and a metal wedge to form the trailing edge of that rudder. The RV 8 has a one piece rudder skin that has a partially bent traling edge that must be finished after the stiffeners have been riveted to the skin.

To accomplish the final bend, you need to build another homemade tool called a bending brake. It is basically nothing more than two long pieces of 2x8 attached with 3 inch hinges from HD. My math skills are a little lacking as I tried to determine the precise centerline placement of 5 hinges on a 49 inch long board. so I divided 49 x 5 and came out with about 9.8 inches. So I measured out 9.8 inches from one end of the board, and started attaching the 5 hinges, only to realize that I needed a 6th hinge based on the measurements I had taken. So this turns out to be a "divide by and add one more" scenario. You can see the remaining spot for the missing hinge in the top photo. My only concern now is that I don't continue to make this same mistake when I have to measure and layout rivets on other parts of the build. Oh well, one more trip to HD and she'll be ready to go.

You basically open the brake wide enough to insert the rudder skin trailing edge, leaving about 1/2 to 3/4 inch gap between the skin and the hinges of the brake, and then you "wanker" down on it" as the aussies would say, until you achieve the final bend. The trick is to make this bend as straight as possible, and to keep from bending it too far. I was very concerned about this because the plans lack any detail about the expected radius of the trailing edge after the bend is made.

I decided to turn to my eldest son for help. He is about to graduate high school, and has completed several college-level math and science honors courses. I wanted to determine a bit more definitively what the finished angle and corresponding height measurements of a specific point would be, to help me determine appoximately how far to apply the bend. I told him the front spar would measure about 3 inches high at it's widest point, and the skin width was about 20 inches. We also figured that the point where the leading edge of the skin attaches to the front spar is close to a right angle (90 degrees). This is not entirely accurate, but was good enough to apply some formulas for experimental purposes. He applied some trigonometric functions and determined that the finished angle would be about 8.53 degrees, and that the height of the front edge of the bending brake should be about 1.2 inches high when the bend is completed. You are not supposed to have anything attached to the leqading edge when you perform the bend, and I was concerned about knowing when to stop bending. That is why I wanted some measurements to go by. I am just simply amazed that there are mathematical ways to apply some precision to this task without it being such a guessing game.

Vans also told me that the radius of the rudder trailing edge bend should be about 3/32 of an inch, and explained that the distance of the trailing edge from the hinged-edge of the brake will need to be shorter or longer if you choose to shim the hinged edge of the brake up a bit to prevent bending the trailing edge too far, as some builders have also done. I am still concerned that I will need to tweak the bend a little after it is attempted, since many others have needed to perform additional fine-tuned bends using other hand tools like a hand seamer. I would rather it be done without the need to "tweak" anything, but I certainly don't want to ahve to order a new rudder skin either. Nerve-racking stuff when you have never actually done it before, but I'll get through it.

When I get closer to actually performing this step I will refine and double check the math numbers to ensure they are correct, and then we will see if it works......

Straightening VS Rib Flanges - Homemade bending tool

It appears that I neglected to include some pics of a homemade rib flange bending tool that I built for the purpose of straightening the rib flanges so that they are 90 degrees perpendicular to the web. this is important because the skins must lay on the rib and spar surfaces to create a smooth, laminar surface for the air to flow over. If the flanges are not aligned correctly, the part will contain rises and valleys in the skin. This will negatively affect the ability of the air to flow smoothly over the surface, increasing drag, and, in the worst cases, causing undesired flight control problems.

There are several posts on VAF that describe how to build this simple tool. I basically made mine with a large enough particle board base to accomodate the wing ribs that I will hopefully be working on about a month from now. The rib shown in the pic is the bottom main rib of the VS. A 2x4 and 2x2 are cut to size, and attached with a hinge. The most important part of the tool is the 11 degree angle that was cut in the 2x4, and the clearance angle at the bottom of the 2x2 handle to allow for the bulge of the rib web stiffener holes. Most builders have found that this "over" bent angle actually sets the angle of the rib flange to the correct 90 degree angle, due to the spring back affect of the metal. You need to raise the bending handle up just enough before attaching the hinge to allow for the thickness of the web on each rib to keep from deforming or scratching the aluminum when the bend is made.

To operate it, you basically place the rib in between the bend handle and the 2x4 as shown, apply a fair amount of forward pressure on the handle for a second or two, and then move the part another two inches to perform the bend of the next section of the flange. When done, you check the angle of the flange with a straight edge to ensure it is 90 degrees to the web, and make minor corrections by hand as necessary. It does not work for curved surfaces very well, so you have to be careful not to change those. That said, most of the rib flange can be straighted using this method. I applied some electrical tape to the bottom of the handle and to the surfaces of the 2x4 that actually touch the metal, to help prevent any scuffing or scarring of the alclad aluminum.

The tricky part about using this tool is that the amount of force required to complete the bend depends a lot on where you grip the handle, and the length of time that the force is applied. It is possible to "over" bend the flange by applying too much force. A little practice is all it takes to get the hang of it. The other option is to pound on the flanges with a rubber mallet. This is very hard on the hands, and it takes a long time to do each rib flange. The bending tool works so much easier and faster, so it is well worth the small amount of time it takes to make this tool.

168 hours Cleaning VS Parts

Pic of the Vertical Stabilizer rear spar and reinforcement bracket after dimpling and countersinking the 22 holes at the bottom which require AN426 flush rivets, since this part of the spar will be flush mounted the last bulkhead of the fuselage later on. If you click on the photo to enlargen it you will also note the score marks on the web of each part, which came from the scotch brite pad that was used to prep each part for priming. Lots of acetone washing with a microfiber cloth remains in order to clean each part thoroughly for priming. Parts will be handled with rubber gloves during cleaning to prevent the transfer of oils from your skin to the aluminum, which may cause problems with the primer adhering to the metal properly. The countersunk holes are a little bit deeper than the dimples in the spar to allow each dimple to seat correctly and allow the parts to lay flat against each other.

Stiffeners clecoed to the Rudder Skin

If you are confused from the previous posts about the siffeners and what they are used for, perhaps these last pics will help clarify. Here they are clecoed to the skin on one side. When the rudder is finished each side of the skin will have its own set of stiffeners. You can see how they taper to a small point or edge as they move further back towards the end if the rudder, and are wider at the front. The angle is used to counteract any torsion moments of the skin, and is the real reason why the term stiffener is used. If you simply applied a strip of aluminum without the angle to the inside of the skin, you would not get the same stiffening quality that is needed here. As more of the rudder comes together you will see how these parts interact with the rest of the structure.

Smoothing the rough cut stiffeners

Here are some pics that show the finished stiffeners after smoothing all the edges on the Scotch Brite wheel. What an amazing tool for working with aluminum. Sometimes the chemical folks come up with the some really amazing things to benefit mankind. Dangerously jagged edges are all made as smooth as a babies bottom. The corners are rounded, and the parts are completed.

The idea here is that the stiffeners must conform to the tapered shape of the rudder. (Small at the tip or trailing edge, and much wider at the front. The rudder is actually a very complex shape that contains multiple tapers from top to bottom as well as in width from side to side. So the stiffeners must be very small at the trailing edge where they essentially come together with both sides of the skin, and they then widen out as the skin gets wider towards the front.

Trimming Stiffener Cont'd.

This is a pic of the safety glasses, ear plugs, dremel tool, and the scrap aluminum pieces you end up with when you are done cutting all 16 stiffeners. Note how sharp looking these are. it is important to clean these up and ensure that they are picked up off the floor as soon as they are cut. I could think of no useful purpose for any of this scrap material, so it ended up in the 86 files (trash). Recyclers will now respond and attack me "En masse" for doing such a foolish thing. So it goes I guess.

More on trimming the stiffeners

The process to trim them is basically to secure the angle to the work bench with the clamps. I absolutely must use two hands with the dremel tool in order maintain control of the tool while it cuts, so it is imperative that the clamps are positively securing the work. If you even suspect that the part is starting to move, turn off the tool and re-clamp the piece before continuing. You line of the cutting wheel so that it si just outside of the trim line for each cut.

I basically started with the cuts that separate each stiffeners from the angle stock, and then reclamped each one individually to make the angle cuts on the flange and do the final trimming. Using the Dremel tool makes this process go quite quickly, but it is also very easy to make a mistake. The key, as with all things about this process, is to take your time and follow the same process for cutting each one.

Tools, Safety, and Trimming the Stiffeners

I used my dremel tool to cut the stiffeners from the aluminum angle. Other tools included clamps, Safety glasses, ear plugs, and several REINFORCED dremel cutting wheels on the standard Mandrel. Do NOT use the small standard NON-REINFORCED cutting wheel as these will shatter as soon as you hit the aluminum. The reinforced cutting wheels will work fine, but you will go through at least 4-5 of them in the process of trimming all 16 rudder stiffeners. The wheels dissipate quite rapidly when cutting the aluminum, so you will need several of them. You MUST where safety glasses and ear plugs, and, as I found out the hard way, even some gloves to keep from burning yourself on the hot dremel tool.

The last thing you need is tiny shards of aluminum in your eyes. Believe me, there are plenty of them hitting your face as you cut the metal. If you are less inclined or do not possess a Dremel tool then a good hack saw or metal cutting blade will work fine. I set my Dremel to a 9 power setting (Almost full speed). I did not want to experiment with a slower setting for fear of binding the aluminum causing the wheel to jump and cut things other than those you originally intended to cut.

Marking the stiffeners

Here is a series of pics that shows the various markings to be made in order to trim the stiffeners from the aluminum angle. You can see the semicircle notches that Vans made and the lines drawn to connect the marks to create the correct trim lines for each stiffener. The only thing I did not like about this process was that Vans attempts to show this in their plans with the angle drawn "flat". They say this is for "clarity," but I found this to be quite confusing. They really need to show a better diagram so that you can understand how the trim lines need to be drawn. Nevertheless, I managed to figure it out.

More on Rudder Stiffeners

In my research, I found that any detail concerning the fabrication of the stiffeners for the rudder and elevators is woefully lacking on most builder sites, so I am attempting to fill that void by providing a bit more detail. This pic shows the labels forsome of the stiffeners, which are labeled from A through H. There are eight per side, for a total of 16 for the rudder. All 16 had to be trimmed from the angle provided from Vans.

The stiffener basically "stiffens" the thin rudder skin to keep it from flexing to much. The only ribs for the rudder are the two end-ribs, one on top adn one on the bottom. I'm not totally certain why the rudder does not contain a more robust skeleton made of fully formed ribs from end to end, but perhaps this has to do with the fact that this is a critical moving part of the aircraft that controls a force called yaw, or the left and right turning capability of the airplane. Perhaps hard formed ribs that would attach to both sides of the rudder skin may be subject to failure and cracking due to the amount of force that this surface will endure over time. It could also be related to weight concerns, since this is the aft-most structure of the entire airplane, and therefore has a large affect on the center of gravity.

165 hours - Starting on the Rudder and finishing the VS

Items 1 through 6 on my previous post have been completed. All that remains now is to clean, prep for primer, clean again, prime, and slam the rivets together to complete the VS. I had to buy some more primer yesterday and spend some time doing early Xmas shopping as well. I wanted to finish the VS over the Thanksgiving weekend, but it did not quite happen. Instead, I spent a lot of time reviewing other builder sites and VAF posts to learn more about creating the stiffeners for the Rudder. I also and actually managed to cut, trim, and smooth the edges of all the rudder stiffeners. Here is a pic of the angle aluminum that the stiffeners must be trimmed from. They are about 3 feet long and contain special pre-punched markings that define where the angles of the flanges need to be trimmed.

155 hours Continuing with VS

Trimmed the vinyl off of the VS skin and almost finished deburring all the holes in the skin. The ones closest to the leading edge are always hard to get to so you usually end up using a scotch brite pad to debur those holes because the deburring tool is too big to slide in between the skin halves. Rib flange holes that line up with the holes in the skin are all dimpled.

Only things left before I can rivet the VS together are:
1. Dimple holes in skin using the squeezer and c-frame
2. Dimple leading edge rib holes that I can't get to with the squeezer by using the close-quarter tool.
3. Clean up the edges of the front and rear spar and the skin
4. Finish edge -deburring the spar doubler that strengthens the rear spar. The forked ends on one end are a bit challenging because you need to debur the edges at the base of the fork. I have a method in mind uaing 220 aluminum oxide sandpaper and a dowel that I can use to make a sanding block to smooth the remaining edge. It's too thick for a scotch brite pad and I can't use the wheel to get into this area. This part was stamped out of a very thick piece of aluminum and contains very sharp edges, so it is important to debur the edges so that they do not dig into the rear spar over time.
5. Counter sink the holes in the spar doubler where the rivets will join the doubler to the rear spar. (22 holes to do)
6. Dimple the matching attach points on the rear spar where the spar doubler will be attached.
7. Prime the parts
8. Rivet it all together

More VS pics

The VS goes together much faster than the HS. Less parts, less drilling, less everything. Here is a series of pics that shows what it will look like when it is all riveted together. First is the rear spar with the bottom rudder hinge and the spar doubler in place, which is a thick piece of reinforcing aluminum that provides support. Second is the VS all clecoed together - it's not really all that big. Last is another shot showing the full length of the rear spar with all three hinges that will attach the rudder (as soon as I build it anyway!) On thing that I found interesting is that the rudder is actually a relatively complex shaped part. It tapers in all dimensions as it goes from the bottom to the top. The rudder is a bit thicker on the bottom and not quite as thick on the top, so the bottom hinge is actually slightly longer than the other two hinges to account for this difference in the shape of the rudder from one end to the other.

154 hours VS work continues

Ribs, spars, rudder hinges and skin for the VS are match/final drilled, deburred, and almost all holes are dimpled except for the skin. I have to break out the soldering iron with the rounded tip again to trim away the vinyl covering that protects the metal from scratches. Then I'll need to rig up the C frame again to dimple the rivet holes in the skin.

Here is yours truly working the drill while I match drill the holes in the rear spar with everything clecoed together and clamped to the bench. Rule number one is always secure the work! I clamped the rear spar to the bench, and also clamped a small block of wood on the back side of the spar where each of the three sets of hinge brackets are located. I did this for several reasons: The hinge brackets are made of steel, and are therfore much harder to drill through.

I applied a lesson that I learned during the HS assembly where I tried to drill the hinges without having a solid backing flush against the hinge. The resulting holes were quite rough, and had to be deburred quite a bit. The compressed block of wood against the hinge bracket ensures that the drill bit maintains a consistent tension as it goes through each of the holes in the aluminum and the steel. The only trick was to use a size of wood that would cover the hole in the hinge bracket and slip in between the clecoes holding it in place. It worked well, and the holes in the rudder hinges came out much cleaner this time.

150 hours back on the build again

Just when you thought I had vanished off the face of the earth, I'm back! After a summers-worth of home projects, and hunting season all but over, I finally manage to start working on the plane again - just in time for the cold weather! So to pick up where Ileft off, after Oshkosh 2010 I had repaired my blunder on the HS, but I still had some doubts about the fit of the end rib to the rear flange on the right side. There was a small gap that indicated that the flange was not quite seating properly. This is a structural concern and I finally stopped wrestling with the decision and decided to drill out the 2 AN470 rivets and do them over again. Read the series of posts about my major repair and you'll understand why I was hesitant to try to drill out any more AN470 rivets. This pic shows the gap. I was able to refit this and close up the gap successfully, and re-do the last flush rivet on the end of left side that I had also messed up, and now the HS is hanging up on the wall above my work benches, waiting on assembly with the fuselage someday down the road.

Here is the 8'4" long HS for my RV8. Just needs some fiberglass tips on the ends that I will install later. I'll probably pull it down again when my elevators are done just so I can test fit them to the HS and dream about the day when it's time to attach them to the fuselage for the very last time.

Now on to the Vertical Stabilizer, or what most folks call "the tail" or "the fin." You can see the frame or skeleton of the VS on the table just to the right of me. More VS pics will follow..

After Oshkosh Airventure 2010 - A Remembrance

So here I am again - seriously delinquent in posting my latest airplane building activities on the blog. Before I start ramping up on all that again, I wanted to take a moment to share a small remembrance of my second journey to EAA Airventure in Oshkosh, (or "SLOSHKOSH,"for reasons I will explain later) which just recently concluded.

The theme for this year's Airventure was A Salute to Veterans. Most of the activities on the grounds and during the daily airshows were geared toward honoring the service men and women and the military aircraft that have served our wonderful country for so many years now. The following is a story about something that happened to me up there that really made me reflect on the true meaning of this year's theme, and it has stuck with me ever since.

After arriving safely in Oshkosh and setting up the trailer for the week-long stay in Camp Scholler, I was experiencing some problems getting the car started, and ended up taking it into a shop that, fortunately for me, was only a couple of miles down the road. Long story short, they drove me back to the campground after I dropped the car off, and by the end of the day the car got a new battery and was ready to be picked up. The problem was that since it was the end of the day, noone was available to pick me up and take me back to the shop to pick up the car.

So I worked out an arrangement to walk to the shop from the campground and pick up the car. As I walked along the side of road, cars wizzing by me, I heard someone saying that it looked like I was in for a very long walk. I turned and saw an elderly gentleman dressed in a WWII Khaki uniform sitting in a chair next to an awning. Under the awning were several tables of WWII paraphernalia - helmets, M1 ammunition clips, dummy 20mm canon rounds, etc.

I stopped to look at the collection, and noticed that the signs that accompanied the display were promoting a WWII museum, which sat almost hidden from view of the road only 20 or 30 yards away. My first thought was that I was not even aware that this was out here - right next to the camp ground at Oshkosh. There was no advertisement, nor mention of this facilitity in any of the Airventure literature, and I found this quite odd, being that the theme for this year was supposed to be a salute to all veterans. In fact, this building and the car shop are the only other buildings on Poberezny road, on which I walking to pick up my car. If you were driving on the road you would miss this building since it sits just out of sight from the road.

I then continued to look at the items on the display table, and I noticed a back and white framed photo of a soldier in a tank crew uniform sitting on the gun of a German Tiger tank. The gentleman informed me that it was a picture of him in 1945, to which I asked, "So how is it that you came to sit on the gun of a perfectly healthy enemy tank?" He then told me that the war had just ended, and that if that had not been the case, the Germans might not have been very eager to allow him to sit on their tank. We both laughed as I acknowledged his response.

I then noticed another photo of Richard L. Bong and his wife Marge, sitting in the cockpit of his famed P-38 fighter. You have to understand that Dick Bong was one of the leading aces of the entire war in the pacific, and was also a Wisconsin Native. His aircraft also sits perfectly preserved at the EAA Museum, with Marge's picture painted clearly on the side, right next to the large number of Japanese flags that represent the number of aircraft he shot down. I had never seen this photo before, and as a devout WWII history buff, that is very unusual for me. The gentleman informed me that he had asked Marge if he could take the photo and blow it up larger than life for display in the Museum. She obliged him, and apparently he also came into possession of the original photo after Marge's passing just a couple of years ago.

I then mentioned to him that it was a shame that more people are not aware of this facility, while it sits in the shadow of all of the Airventure fanfair. I also told him I admired him for sitting in the hot sun to help promote the preservation of lessons and memories from what seems to be a long time ago now. He simply smiled, looked me in the eye, and replied "Well, that's OK, we are old and retired and have nothing better to do anyway."

He then offered me a drink of water, which I politely declined, thinking he most certainly needs it out here in the hot sun more than me. Then I shook his hand, and thanked him for his service to our country, and for sharing some of his history and memories with me. Then I wished him well with the museum and his efforts and continued on my way.

As I walked away something kept bugging me about what he said to me just moments earlier, that they were old and retired, and that he and his friends had nothing better to do anyway, and that people were too busy to remember all of those things that happened so long ago. It has been almost two weeks now and it has continued to bother me to the point where I felt that I just had to write this down. The thing that bothers me the most is that I failed to ask him his name, or to find out more about what unit he served with and where he served, because I was too busy trying to get my car back.

So, I guess the only thing I can do at this point is to make this blind statement in response to his comments, and hope that he and all of his brothers and sisters who sacrificed everything for which we should all be so eternally greatful will somehow hear and appreciate these words:

I will ALWAYS remember, and I will ALWAYS care about everything that was done by all those who have ensured the freedoms that I am able experience today - -freedom to build and fly my own airplane; freedom to live in a country free of tyranny and oppression; and freedom to share my experiences with those that I consider to be my friends, and to have them share their experiences with me - -even from those whose names I will never know, or that I have long since forgotten.

That is my personal Salute to Veterans, and a memory that I will cherish for the rest of my days. You just never know what will happen when you go to Oshkosh to experience Airventure!

Repair done on Wednesday, May 19, 2010

Ron Duren to the rescue (Again). He graciously accepted my invitation to drive to my house to buck 4 rivets to finish the repair work that took me most of the week to complete. He handled the bucking bar (left hand), while I drove the rivet gun (right hand). Notice the cool EAA T shirt that defines a pilot, and, yes, the wing parts still in the crates in the back ground - still working on that project.

And the finished task - 4 nicely set rivets, 2 on each side of the repair flange. Although standard aluminum patch practices may call for at least one more rivet on the spar-side of the repair, I stuck with 2 rivets on each side. The reasoning is that the skin is providing support with all the rivets that are attaching it to the spar and to the rib, so I think that there is adequate support in this area. I used an offset dome headed cup set for the rivets that attach the new flange to the spar web, which is about 5 inches longer than the normal cup set I would use for AN470 structural dome headed rivets. This allowed sufficient clearance of the rivet gun from the skins so that they would not get all banged up during the riveting process. Note that the repair was placed on the forward side of the spar web, and not the back, although when I marked the holes for the location of the rivets, I had it placed on the aft side of the spar web. This was because this was the only side that I could fit a straight drill bit (used a 12 inch extended number 30 drill bit to drill the holes.) Yes, I could have used my angle drill attachment to drill the holes from the other side, but I find this tool to be very inaccurate in terms of being able to drill a nice, straight hole, unless you can slap it in a vise to keep it from moving. So I opted to drill from the back side using a longer drill bit, and it worked out pretty well that way.

And from the other side - 2 more nicely set rivets, all in the original holes of the new rib that arrived from Van's "just in time." For some reason we had a little difficulty with the holes in the repair piece lining up with the holes in the rib after the piece was riveted to the

spar. This was strange to me because everthing had clecoed together perfectly before we started riveting. If I had one thing to do differently about this repair (hopefully I will not have to do this again but...) I would not match drill the holes in the rib to the repair piece until AFTER I riveted the part to the spar web. What I did this time was match drilled the rib holes to the repair piece after clecoeing the piece to the spar, but BEFORE it was riveted to the spar. If I would have waited until after I riveted the piece to the spar flange to drill the holes for the rib attach points, they would have lined up perfectly, which caused the mis-alignment of the holes on the other side. I can only guess that the act of riving the rivets to attach it to the spar pulled everything up tightLesson learned, but hopefully will not need to be repeated! Whew, that was a lot of work! But at least its done, and so is the HS riveting, for the most part. More on the finishing touches later.... Thanks again Ron for all the help.

HS repair cont'd

Another blurry pic. Shows progress with th nibbler. The only draw back is that you cannot control the precision of each cut very well, so some are deeper than others. Here you can see some of the little pieces that have to be nibbled away - almost there...

For anyone with experience in such matters, no this is not mouse poop, even though it looks like it from a distance. Believe, me, unfortunately I know what mouse poop looks like! No sign of them in the last 8 months or so, so that's a good thing. These are the remnants of the metal removed from the flange by the nibbler.

The business end of the nibbler in its non-cuttting state

Now in the cutting position. It generally will remove about 1/8 inch of material by about 1/4 inch with each cut.

The end result after nibbling and grinding the edge to a smooth edge with no burs. You can also see the marks I have made on the spar flange when trial fitting the new flange in place. That was a lot of fun by the way, because I had to use 3 hands and some tape to hold everything into place. Then I had to fit my sharpee in there to draw some reference lines and mark the hole locations in the spar web. All the trial fitting had to be done with the end rib clecoed in place. Needless to say, since I was the only one present during this delicate balancing act, I have no pics of the part taped into place during this operation.

Another shot showing the degree to which the flange was trimmed. I only cut enough to remove the bend, leaving as much of the straight part of the spar web in tact. All of the metal dust and chips from drilling/nibbling were cleaned out of the areas as well. You don't want any of this material settling into the crack and crevaces where they can start to fatigue the metal between the spar and the skin over time. Everything was spic and span before closing it all up, hopefully for the last time.

Repair of HS Tip - Hobbs 140 hours

So the repair process began. All through last week, and ending with Ron coming over to help me buck the 4 critical structural rivets for the flange repair and the re-attachment of the end rib to the HS. A series of pics of the process follows:
A bit blurry - did I ever say how much I don't like digital cameras, except that you did get instant electronic pictures I guess. This shows the top hole that was also drilled through. This entire flange had to be cut and trimmed away, and a replacement flange fabricated and riveted in its place.

Just some of the many tools used to complete this repair, and a shot of the more or less finished part that I had to cut, bend, and drill. The wood form block is the same one from earlier posts where a 1/8 inch radius bend was required. The angle finder was used to verify that the bend was exactly 84 degrees to match the angle from the forward spar to the side of the end rib where everything attaches, resulting in a 6 degree angle, or the same angle that the roots of the spars and the support angle brackets were bent to long ago. The two holes have been measured and drilled to assure proper edge distance requirements are met. Other tools used were a nibbler, my dremel grinding wheels and articulating saw attachments, metal cutting saw blades, and more.....


Another bad pic - attempting to show the angle and how the part was positioned between the two blocks during the forming process










Fitting and sizing up the side that fits up against the inside of the rib. You can see the relationship of the rib holes to the flange. These are the two remaining holes that have to be drilled. The plan is to rivet the new flange to the spar first, then fit the new end rib into place, and use the existing holes in the rib as a guide to match drill the holes into the other side of the flange.



Shows the plastic hammer I used and the form blocks and the aluminum part in the vise and being formed. Just had to eyeball this a bit and make sure that I did not force the bend over the 84 degree mark. This is actually very easy to do, and my guess-timate was very close to where it needed to be - I was only about a half degree off. You just start tapping the hammer at the base of the bend and it starts to fold right over.

Shows the part up against the angle finder - 6 degrees - with a 1/8 inch radius - just as it should be.









Now for the other difficult part of the fix - how to trim off the damaged flange from the spar. Lots of measuring involved here - not to mention trying to decide what tool/method to use to remove the flange. The trick was to remove only enough material that would not compromise edge distance on the spar web, which meant only trimming off enough material right up to where the bend occurs, without removing any material running the length of spar web, if that makes sense. Then ensuring that it is straight and free from burs, all within the confines of a skin that is already riveted in place on the spar top and bottom. Dremel cutting wheel was out of the question - too much risk of skipping and cutting into the skin, causing even more problems. Hack saw was another possible solution - but it would have to be done by hand. In the end, as shown in the pic, I chose the nibbler (man I love this tool!) I could cut small chunks out at a time, with fairly precise control over the amount of material being removed. Yup, that's my fat hand in the foreground, next to the small opening at the end of the HS.

Good News/Bad News

So I was able to transport my almost-complete HS up to Erie Airport past Saturday, where one of the EAA chapters I belong to, Chapter 43, was having a hangar picnic. Lots of great food and great company. There were not one, but two completed RV 10s in the hangars, and so I spent a fair amount of time gawking at them, and drueling with envy at how big and roomy this home built airplane is. I met with a tech counselor, Bill Truax, who looked over the damage to my wing skin and basically told me that it could be filled, won't ever crack, and basically told me not to worry about it, and to KPR (keep pounding rivets). That was the good news.

Now for the bad news. Later that evening, after getting the HS back home, I should have simply started closing up the rear spar and the ends and called it good. Instead, there was one rivet that attaches the end rib on the right side that did not quite get set as well as I would have liked. So I thought that I would drill out this rivet and and replace it, and then finish everything up after that. the first removal went without incident, but the attempt to reset the rivet resulted in a very badly set rivet, so I made the decision to drill it out as well, and try again. As the following picture shows, my drill slipped and I ended up drilling a new hole right through the end rib and into the spar flange that it was attached to. I then had to get creative with a pair of needle nosed pliers in order to snip away at the remaining rivet head in order to get it loose enough to remove. It did not matter, though, since the damage was already done.

A phone call to Vans yesterday, followed by a comfirming phone call to EAA HQ tech counselors today, resulted in a recommendation to:

a. Completely cut away the portion of the forward spar flange that connects to the end rib (not shown in this pic but I will add other pics as I affect this repair.)

b. fabricate a new flange part for the end of the forward spar that will need to be riveted onto the end of the web of the forward spar

c. Order a new end rib (done today), locate and final drill all the holes, debur it, dimple the holes, flute the edges, and prime it. Then finally try to rivet it in place once again.

Obviously this will set me back a bit from finishing the HS, having learned yet another very important set of lessons in the process. I'm sure this will not be the last time I have to figure out how to affect a repair like this, but, needless to say, I am very disappointed in myself right now, and in hindsight I should have left well enough alone. That said, you just have to press on when things like this happen, and realize that problems like these can still be resolved, albeit with a bit of extra effort.

The fabrication will take me some time to complete, because there are some precise measurements that have to be made for the correct size of the repalcement piece, and an 84 degree bend that needs to be made to properly line of with the web of the end rib. Lots of cutting, clamping, and drilling to do. Looks like the dimensions needed to fabricate the part are to use .032 inch thick alclad aluminum, and both sides of the piece will need to be about 1.5 inches long x 1.5 inches wide. The real dimension turns out to be about 1.65 inches x 1.39 inches in order to achieve flanges that are 3/4 of an inch wide on both sides. Bending metal is yet another specialized skill that one has to become familiar with, and it involves quite a bit of math skills and knowledge of metal properties in order to get it right. I won't bother listing out all the detailed formulas involved in figuring out the correct dimensions, except to say that I have spent most of my evening reviewing and calculating all of this. I figure this will set me back at least a week on the HS. Wish me luck I guess.

The whole HS assembly - almost there......

What a nice pic of an almost finish airplane part! I can't finish riveting the skins until I have a tech counselor look at my damaged skin this weekend. Hopfully the verdict will be that I can proceed without replacing the skin, and then I can finish attaching the rear spar, shown here clecoed into position. The remaining rivets can be squeezed instead of bucked - a welcome relief from all the bad rivets I had to drill out and replace thus far.

Riveting is definitely a skill that has to be practiced. Unfortunately, I am finding out that not even the courses that you take from EAA, or the project kits that you can work on, provide the same challenges that you experience on the real airplane parts. You have to learn how to feel the bucking bar, how to hold just right in many different positions, and how to hold the rivet gun, how to contort your body and hands into just the right position, and so on. It will definitely be a challenge when trying to do this on my own, but the good news is that the wing and fuselage parts are somewhat bigger, making them at least a little easier to work with.

Left Side HS Skin almost complete

With Ron's help, this is the bottom side of the left half of the HS, almost completely riveted together. The only thing remaining is to attached the other half of the stabilizer and then finish riveting the ends and the rear spar. The whole assembly turns out to be about 8 feet 4 inches long.