Welcome Captain Buzz!

I noticed you joined my blog site as a follower. Nice to have another experienced builder chiming in! Welcome!

382 hours on the hobbs - Sometimes taking the small victories is good enough!

Got another stiffener angle from Vans and remade the E720 L stiffener than became damaged in my previous attempt to get them back riveted to the left elevator skin. I have also realized that I have not posted any pics in several posts so it's time to change that. So bear with me while I take a short trip down the past.

Here is a shot of the measurement for the E720 L stiffener where Van's wants you shorten the back end by a specified amount from the second to the last rivet. In this case the measurement is 2 inches from the hole.

And now for something I just could not pass up, even though it is not exactly airplane related. Back up on the mountain for some deer hunting. My son Adam was able to hunt this year so we both went up the mountain to see what we could see. So with that in mind, I ask you, what is wrong with this picture?!

And here is one with the skin being dimpled using the C frame. No extra holes poked in the left skin like I did on the right elevator skin - thank goodness for that!

All the stiffener holes dimpled. One thing about this process that I do not like. Since you don't really get to match drill any of the other holes for the attach points for the spars and ribs until after you bend the trailing edge of the skin, you are forced to prime areas with holes that are both undrilled to final size and that have not been dimpleed yet. Some have questioned the integrity of the primer if you primer first and dimple later, but I ahve not seen any appreciable flaking or detatchment of the primer from the area where the dimple was formed, so I guess it's not such a big deal.

Napa 7220 self etching primer in a can being applied to the stiffeners and the trim server mounting access plate, etc. My little chicken wire paint box works quite well for the smaller parts.

Inside left elevator all scuffed up with scotch brite pad (maroon) and cleaned with microfiber cloth and acetone. Ready for primer.

Too bad halloween is over! Warning! The following pic is very grotesque and not for the faint of heart! You better watch out if you get a can of primer in my hands - lethal and extremely dangerous for sure!

On a more serious note - please, if you use this stuff, remember that it contains ACID that EATS METAL. This is about the last stuff you want to be breathing, so the mask is an absolute MUST, even though the primer comes in a rattle can that looks like any other spray paint in a can. Here is the skin after priming. I really like the way way this stuff lays down.

Tape applied to the rivets for back riveting the trim access plate and the the stiffeners.

The trim access backing plate after back riveting. Interesting to me that the side next to the forward spar has NO rivets to hold it on the skin. I think the curved flange sits up against the back of the spar but not 100% sure about that. The other holes that you see are for the nut plates that will secure the cover. Some additional holes will drilled as well to accept the rivets for the two brackets that will hold the trim servo in place.

Stiffeners on the bottom back riveted with no problems.

And then the problem occured. I was on the last stiffener E720L. Although it is hard to see in the pic, the area where the primer is scratched off is the side of the dimple that became completely caved in. Even worse is that it happened to the very last hole in the stiffener, closest to the trailing edge of the skin, where a lot of stress can occur. Not a great place to have a potential defective part or assembly. How this happened is still a huge mystery to me. The only thing I can figure is that I did not adequately hold the skin back far enough to clear the rivet gun set retaining spring, and the back rivet set may have slipped to the side and started driving the rivet at an angle. After two attempts to drill out and reset this rivet as per my previous post comments, the stiffener was damaged beyond usefulness.

The last two pics are the result of many steps to fix the problems that this caused:
- fabricating a new stiffener to replace the damaged one
- setting the skin back on my close quarter dimple tool to try to reshape the dimple in the skin so that the 1097 4-3.5 Oops rivet head would sit more flush after drilling the hole to 1/8 inch to accept the wider diameter oops rivet
- using a 1/8 inch drill bit and the same sized hole in the skin as a guide to mark the surface of the center of the last hole in the stiffener. Remember that Vans makes you drill this final hole in it's entirety. It is not predrilled like all the other holes, so you have to drill this hole out all the way.
- drilled the hole from the previous mark using a #40 drill bit first, so that the correct 3/32 dimple could be formed arund the hole
- dimpled all the stiffener holes with 3/32 dimples
- drilled the last hole in the stiffener a bit larger to 1/8 inch using a #30 drill bit so that the oops rivet would fit through the holes in both the skin and stiffener
- primed the stiffener
- inserted and taped the rivets into the skin, ensuring that the 1097 AN4-3.5 rivet was in the last hole, and the normal AN426AD3-3.5 rivets were in all the other holes
- Got my kid outside to hold the skin back so I could focus entirely on holding the back rivet set steady and the stiffener firmly to the skin
- Successfully back riveted set all the rivets on this last stiffener.

The pic above shows the oops rivet sitting nice adn flush on the skin. HEad is the same as the other rivets, but the shaft is thicker. WHEW, am I glad that worked out.

So I have officially set my very first oops rivet. An interesting thing about these rivets is that they have a slightly raised center section on the manfactured head side that you don't see on the regular AN426 flush rivets. This initially caused me to think that the rivet was going to sit a bit proud of the skin, but in reality it sits just as flush as all the other ones. Another concern was proper rivet length. I was not sure that using a 1/8 inch thick rivet of the same length as the AN426 flush rivets would result in the proper shop head dimensions, but this seemed to work out just fine as well. Checked it on my rivet gauge and everything seems to measure up correctly. I am still a bit concerned about clearance with the rivet head on the opposite side of the skin once the trailing edge is bent, but I'll worry about that later. For now I am just glad that I got the stiffener replaced and riveted to the skin correctly.

There - all caught up now!  Next is bending the trailing edge of the skin and trimming off those pesky tabs.

380 hours on the hobbs - riveting stiffeners

Well, got all the stiffeners riveted, except one. Started at the trailing edge, working solo. Using my arms and hands to force the opposite skin back far enought to clear the rivet gun and retaining spring. Thought this would be the same process as before - back rivet the stiffeners and move on. Well, guess again. The rivet on this particular siffener ended being severely folded over. So I drilled it out and inspected the skin and the stiffener. The flange of the dimple had been severely deformed on one side. I tried to reset it with the dimple dies but I don't think I did any good. The hole ended up just a bit enlarged so I decided to use slightly longer rivet to fill the hole. The rivet folded over again. I drilled it out and basically stopped all work on the elevator out of total frickin disgust. How could such a simple stupid process end up screwing things up so bad? I couldn't believe it.

Net step was to decide to use what is affectionately known as an "OOPS" rivet.All that means is that there are a set of 1097 odd-sized rivets that have the same head size as a standard AN426AD rivet that fits the same dimple, but contains a wider shaft. SO instead of a 3/32 inch diameter these rivets have a 1/8 inch diameter. All you are supposed to have to do is drill out the oblong hole to 1/8 inch, insert the rivet, and reset it - no problem. Except of course in my case, where the rivet head is not sitting very flush in the dimple any longer. Now I have a bad dimple with an oversized hole drilled in it, and no easy means of trying to reset the dimpleto make it fit the 1097 oops rivet properly. Worse case scenario, I need a new left elevator skin and a new stiffener. Best case is that I will figure out a way to reset this dimple in the skin so that the oops rivet will fit correctly, order a new angle so I can form a new stiffener, and try to reset it again.

THIS REALLY SUCKS! What a way to end a vacation.

I needed to regroup and think this thing through a bit so I did nothing on the elevator today. Instead I spent most of the day revewing Avionics info from the Grand Rapids, SafeAir, Garmin, Dynon, and SteinAir companies. The thing that forced me to start going down this road is that once I build the left wing, I need to determine what Pitot solution I need, and I will need to order the parts for the installation of the correct Pitot mast as a result. The type of Pitot tube I use may be dictated by the type of EFIS, or electronic flight information system, I employ in the aircraft.

Right now I am favoring the Grand Rapids over the Dynon, for reasons I will not get into right now. The only thing I will say is that both of these units work on slightly different principals, and one requires use of the pitot static system where the other does not seem to rely very much on this. This difference in design will determine what pitot/static system I need to employ. For right now I think I am siding with the GRT Horizon HX EFIS with a dual AHRS unit. AHRS is short for attitude/heading reference system. The EFIS and AHRS combine to provide basic and advanced flight instrumentation of the airplane, or the "glass cockpit" components that replace the standard "steam gauges" of the past, including the airspeed, attitude, altimeter, Heading Indicator, Turn Coordinator, and VSI. I will then use the Dynon heated pitot tube, which contains two separate air lines to provide airspeed and Angle of Attack reference, and will most likely cap the AOA on the pitot tube and not use that, since the GRT Horizon apparently has a different method for calculating AOA which does NOT rely on the pitot static system.

For those not familiar with advanced aircraft avionics, I know this is a mouthful. Don't worry, I will go into more detail on this subject when the time is right. There are lots of acronyms, terms, and concepts to understand about all this. Basically you can just think of it as replacing all those traditional gauges with a video game that has all sorts of bells and whistles and really colrful displays all crammed into one screen.

Next steps for me - order a new angle for a new stiffener from Vans tomorrow. Then try to reform this stupid dimple in the skin. Then I can continue with preparing the skeleton and trim tab. Just another day at the factory..........

378 hours on the hobbs - Skin, Trim Support, and Stiffeners Primed

Spent the day today (my last day of vacation for a bit) scuffing and cleaning the left elevator skin, stiffeners, and trim support plate, as well as the two back plates for the forward spar. I also got the rivets taped up on the bottom side in preparation for back riveting tomorrow. I will post pics tomorrow as I am too tired to do it now.

I spent time reviewing Steve Riffe's Builders log Wing section. Plan on making a Wing cradle similar to his - really like his design. Then there is the Wing Jig. This is a bit of a dilemma for me. I received a mobile jig (not affixed to the floor) from a fellow builder, and noted that Ron put his on casters. Steve is building a quick build so he did all his finish work from the cradle, and did not have to build the jig, since his wings are mostly complete from the factory.

I really want a solid jig for both wings, and would prefer to set the vertical posts firmly between the garage floor and the joists for the garage roof, but I have reservations about the crappy uneven garage floor that I have, combined with temperature changes and winter heaving of the ground, and the affect this might have on my wing jig components. Last thing I want is a twisted wing. I built enough of those for several of my RC airplanes to know what affect that can have on flight characteristics. Anyway, I still have some time to mull that over before I commit.

Ordered parts and supplies from Vans

I made some corrections and added some clarifications to my previous post about resolving the potential build problems with the left elevator and trim tab, so please review it again if needed.

I also put an order into Vans yesterday. Consisted of the following:

24 MK-319-BS pop rivets (for closing up small ends and hard to reach areas of the riblets, elevator and trim tab)
24 AD-41-ABS pop rivets (Used for closing up the leading edges of the elevators. I drilled a ton of these out trying to close up the skins on the rudder.
1 E703 elevator tip rib (to make the riblet for the inboard end of the trim tab)
1 E720H5 predrilled stiffener angle (to replace the one that I screwed up while cutting)
2 K1000-3 Nut plates
2 K1000-4 nut plates (Will decide which size to put on the forward area of my elevator tip ribs to provide an attach point for additional lead after paint is applied. Great tip from Steve Riffe and others.)
14 AN470AD4-6 solid rivets (To replenish those that I cut down and used to attach the control horm to the right elevator)
1 Flop Tube IF-4/6  - This is a special fuel pickup tube for the fuel tanks on the the wings that can "flop" up or down or from side to side to allow continuous fuel flow during acrobatic flight, unusual attitudes, or times when fuel levels are low in the tank and you experienced turbulence that causes shifts in the fuel level that need to be followed by the fuel pickup line. I have had quite a bit of experience with this from my RC airplane building days, where even the "trainer" airplanes are capable of sustained inverted flight. they use a "clunk" tank system that basically contains a heavy weighted tip on the end of flexible fuel line so that the fuel line will follow whereever the fuel happens to be in the tank. This is just a bigger version of the same principle with a few more parts and functional aspects to consider. I will only use one in the left wing tank, and will plan on switching to that tank for all aerobatic maneuvers..

Time to start thinking about the wings and the several things that will be needed as wing construction progresses.
I spent considerable time over the past two days catching up on ALL of Ron Duren's Wing constructions posts. Tons of good info in there. SO much so that I will be revisiting it often as I begin building the wings in the not-to-distant future.

I can't remember where I read this recently, but it is so true when you start building one of these things. You have to think about building the airplane from the inside out in order to make it easier to include consideration for things that will be added to the airplane much later in the build. These include such things as:

- attach points for wire runs an routing
- wire needs for various components, such as nav/position and strobe lights, landing lights, heated pitot tube, antennas, pitot static lines, tank vent lines, etc.
- Light assemblies and locations
- Pitot tube style, function, and location
- fuel pumps

and so on....

I also have one other suprise that will require additional electrical wires in both wings, but I will save the details of that for later. I am still in research mode trying to determine what electrical system needs I will have, but I will need to account for additional electrical wires for what I have in mind. It will definitely make my airplane one of a kind I think, and I am excited to get to the point where I will implement it.

So right now I am waiting for stuff to arrive from Van's, and will continue with stiffener prep for the left elevator tomorrow.

372 hours on the hobbs - trimming stiffeners for Left Elevator

After having spent quite a bit of time researching build methods employed for the left elevator and trim tab, I finally got back to actually working on the build. We have had two snow storms in the last 2 weeks that have dumped relatively large amounts of snow for this time of year, and so the shop is quite cold in the evening - despite my efforts to heat it up with my little radiator heater that I bought from HD.

Here is an excerpt from the plans for the RIGHT Elevator that I almost missed. Lots of fun trying to figure all this out when they make notes for the left elevator parts on the right elevator plans and vice versa. The stiffener part numbers are slightly different for the left elevator, in that you are supposed to trim stiffeners E720 J, K, and L from stiffeners D, E, and F. For some reason that still escapes me, they have added some notes to trim the J, K, and L stiffeners a very specific amount. At first I could not understand what they meant, since the notes simply said to trim the aft end of the stiffener based on the dimension given for each one. One example said that that the D stiffener is to be trimmed X= 1 7/8. I had no idea what X was until I reffered to the stiffener detail on the right elevator plans as shown below:

So X is measured from the second to the last hole to the end of the stiffener. The mystery is that this trim measurement did not apply to the D, E, and F stiffeners used on the Right elevator, and I do not know why. All you did was cut them from the angle at the designated marks, and debur the edges, which shortens them up a bit from the original cut. It is clear that they want you to trim the stiffeners for the left elevator just a bit more than that. I am only guessing, but perhaps it has something to do with the flex on the left elevator that may be caused by the added force of the trim tab, and they want you to shorten up the stiffeners to avoid additional cracking that might occur. Again, that is just a guess.

Now for the next one. If you use the dremel cutoff wheel as I do for cutting most of my parts, you will inevitably end up with a mistake that requires a new part at some point. The wheel got away from me and wrapped itself around the stiffener just enough to put a nice gouge right to the rivet hole. This part is toast and will now go into the scrap heap. That makes 4 that I have messed up and either had to repair or replace.

Now that I understand what "X" is, I tranfered the measurements to each of the D, E, and F stiffeners, and included a mark that shows the position of the last hole which has to be match drilled from the hole in the skin.

After screwing up one of the H stiffeners and freezing my tail off after rough cutting one of the two pieces of angle for the longer J, K, and L stiffeners, I decided to call it a night. I will have to add another piece of angle with for the H stiffeners to my order from Van's, and will have to wait for it to arrive before I can finish the prep for all the stiffeners. Just to clarify, until I saw that note that described what "X" was supposed to represent on the plans for the right elevator, I thought that I was supposed to measure the distance specified in the note from the end of the stiffener moving forward.

For those of you that are fellow builders, do not make that mistake. X is measured from the second to the last hole moving aft, exactly as shown in the stiffener detail in the plans for the right elevator. If you do it the incorrect way (from the end moving forward), you will end up removing too much material from the end of the stiffener. Other builders did not seem to have a problem with this, but it sure messed with my head for a while. Lesson learned is to make sure you read ABSOLUTELY EVERYTHING ON THE PLANS as well as in the instruction book. All too often there are notes and instructions on the plan views that are not mentioned at all in the steps in the book.

Sorry if this offends some of you out there, but my personal experience with engineers that try to write instructions for putting together the things that they design is that most are not very good at it. They tend to omit things that they think are obvious based on their own level of knowledge, and this causes problems for the rest of us non-engineer types. Years of reading less than clear instructions for putting together model airplane parts are the basis for my experience in this area.

Building tips and to do list for left elevator and trim tab stuff

I have been doing a bit of research on many different builder sites to gain a consensus of what to do to avoid the problems experienced by hundreds of folks when completing the left elevator and trim tab assemblies. There is so much useful info out there that I am starting to become overwhelmed. So this post is dedicated to listing several pointers and things to be done to ensure that the remainder of this part of the build is as error and headache - free as possible. If nothing else, this list will show just how involved this process really is, and why it takes so long to do it all correctly.

1. Use riblets instead of bending the tabs on the elevator and trim tab- ABSOLUTELY! I need to make 3, two of them from the ribs used in the airfoil practice kit from the RV Sport Air workshop, and one from the end of an E703 elevator tip rib. I need to order the additional tip rib from Vans, and will most likely do that tomorrow. I checked the dimensions of the angles of all the ribs, and there is a bit of a difference between the E703 and the practice kit ribs, but apparently this works out correctly of they are used on the right places, or maybe it is a moot point and you just need to cut them on the right place to get the correct dimension for the riblet. If I have it understood correctly, I will use the two practice kit ribs for the elevator and the outboard end (small end) of the trim tab, and the E703 tip riblet for the inboard section of the trim tab (closest to the Rudder).
2. NO, I will NOT bend the existing tabs, but will cut them off instead, using a reinforced dremel cutoff wheel and my flex shaft extension that I got for Xmas last year.  Even though I have found several sites that explain and show pics of the correct way to bend the tabs on the left elevator and the trim tab skin, it's just too much work, with a very high percentage of screwing it up, and I think it is also a really bad decision on Vans part to continue with this poor and troublesome design implementation.
3. I WILL NOT bend the trailing edges of the trim tab OR the elevator skins until AFTER cutting off the tabs on each end. (not talking a bout the tabs on the skins, but the normal being of the trailing edge). This is actually more important if I was going to bend the tabs instead of removing them, but to be consistent, I will delay bending the TEs until after the tabs are removed.
4. I WILL leave at least 1/8 of an inch EXTRA material on the skins where the bend tabs are located to ensure that I have sufficient depth to retain a 3/32 inch clearance between the edges of the elevator and the trim tab. You can use the webs of the riblets to close up the gap and form the crisp edge between the elevator and the trim tab by waiting to rivet them to the skins until after the hinges have been final positioned and drilled. Then you can position the riblets to provide just right clearance, drill the rivet holes, and attach.
5. There is some mention on some sites about leaving the stiffeners off of the area where the rear elevator spar is attached to the elevator skin, and this has to do with hving enough clearance to get a no hole yoke inside there to use hard rivets instead of pop rivets. Apparently if you back rivet all the stiffeners in this area, and perhaps this is even another area where not bending the TE of the skin comes into play, then it makes it hard to rivet this spar into place with solid rivets. I may need to think about riveting the bottom of the spar first, followed by the top, or perhaps this has  more to do with leaving the riblets unattached so you can get into the space with the no hole yoke - just not quite sure yet.
6. I WILL NOT attach the riblets or drill the rivet holes for them until I know where they need to be positioned to provide the correct 3/32 inches of clearance between the trim tab and the elevator.
7. I WILL remember to check for any interferance of the riblet flanges with the holes for the trim tab control horn to ensure that I will be able to attach these correctly. Apparently this bcomes an area of concern depending on your decision to place the riblets with the web facing in or out.
8. I WILL place my riblets (Pending the answer to concern number 7 of course) as follows: Elevator and outboard riblet will be web-out, and the inboard trim tab riblet will be web in. Why? Simple. Web out is the same end result that you would get if you were to bend the tabs on the end of each skin. This reduces drag as well as eliminates areas where ice, snow, mud, dirt, or any other foreign substance can accumulate and cause other serious problems. The inboard riblet will match the contour of the root rib of the elevator (web in), and will allow solid rivets in this area. This area is always checked on every preflight, and is easily accessible to check for foreign debris and remove it. Having the web in also allows the use of solid rivets instead of pop rivets.
9. Where blind or pop rivets are necessary, I will use MK319BS rivets, with holes drilled to 7/64 of an inch for a good tight fit.
10. I WILL NOT make riblets that have an additional set of tabs on the top and bottom that will overlap the flangs of the rear elevator spar. They would not have existed had I chosen to bend the tabs, and there is NO REASON to add them to the riblets, which are providing a SIGNIFICANT AMOUNT of additional structural support anyway, moreso than you would have by just bending the ends of the tab skins. The other reason I will not do this is that it would require a great deal more fabrication effort to include these extra tabs, and I am just not willing to go there. I include this step because some builders have gone the extra mile by forming a riblet with additional tabs that overlap the rear elevator spar or the forward spar of the trim tab.
11. For the next Lead counter weight mounting hole drilling exercise for the left elevator, I WILL do that differently than before. Found a great post on a builders web site where he described how he did it, and it just so happens to be the same method that I was mulling over in my brain as I started to free-hand drill the mounting holes for the right elevator. In fact, I used a similar process to mark and drill the holes for the HS404 and HS405 ribs on the HS a long while back, and it worked great.

The process is:
- Cleco the ribs, counterweight, and counterweight skin in place per the plans.
- Transfer the pre-punched hole location from the counterweight skin to the front of the lead counterweight using a sharpee. These holes are pre-punched to #41 size so they are small, adn provide a precise starting point for each hole.
- Take apart the counterweight assembly, and take the newly marked lead counterweight to the drill press, and drill the holes in the counterweight using the drill press. Now you have two straight holes in the counterweight that can be used as drill guide for drilling out the forward flanges of the tip rib and the counter balance rib.
- Re-assemble the counterweight parts, drill out the holes in the front of the counterbalance skin to final size, then drill the holes in the front flanges of the tip rib and counterbalance rib by running the drill bit through the previously drilled holes in the lead counterweight.

This process ensures that the holes in the rib flanges should be smack dead center without any risk of screwing them up as some have done by free handing the drilling of the counterweight. Should have done it this way for the right side but it came out OK I think.

So my brain is tired after all that. I am sure I missed some things, such as ordering the tip rib, some more MK319BS pop rivets, and some AN3 or AN4 nut plates for adding additional weight to balance the elevator, should that become necessary after painting.

As you can see, there is a lot going on during this assembly..........