Cut the New Access Panel Hole in the Left Wing LE Skin

As I hinted in my last post, the new access panel from SafeAir ends up overlapping the access hole that Vans had already cut in the bottom of the Left Wing LE skin. So the mission became cutting the opening for the new access panel and figuring out how to seal up the existing one. Where this becomes a bit complicated is trying to account for the space of the underlying support/attach brackets for both panels, because these also overlap each other on the underside of the wing, and are larger than the removable panel since they have to permanently attach to the wing skin while also providing enough metal to serve as the mounting flange for the panel.

The last piece of complexity for this whole mess is a decision that I have to make about the subskin I am fabricating. In a previous post titled "Getting Ready For The Big Cut" I mentioned that I was getting ready to trim away a lot of the subskin structure as it would not be needed. the only reason I had not done that already is because I needed the full skin in tact so that I could accurately match drill rivet holes in the skin, the subskin, and the two rib flanges, and I also was not certain where I was actually going to trim the subskin for its intended purpose - to serve as the mounting platform for my detachable leading edges I plan to fabricate.

After reading the instructions that came with the SafeAir access panel kit, I decided to start with cutting the new opening for the new access panel. they give two measurements that I think I have already mentioned - 6 inches and 2.25 inches, to locate the new panel.I measured and then drew the outline on the Le skin.then I had to determine what radius was used to create the new panel, because it was obvious from looking at it that it was not the usual 1/8 or 1/4 inch radius, and was much bigger. After some creative measuring with a plastic hole template that I bought from a school supply aisle at the store a long time ago, I determined that the radius was 1/2 inch.

This then meant that I needed to buy a new unibit (step drill) from HF aircraft supply that had a 1 inch diameter step, as none of the ones that I currently owned were that large. Before I could drill the 1 inch holes in the Le skin I had to measure the radius of .5 inches by measuring that distance along the straight edge on either side of each corner. Where the lines cross is .5 inches. then I decided to place the pilot hole just a bit outside of that mark, because you need to leave some excess material and file your way down the final fit to ensure that the access panel fits nicely into the opening. This next pic shows the .5 inch marks and the #40 pilot holes I drilled:

The next reality was that in order to drill the necessary 1 inch holes with the new unibit, I would have to be able to raise up the skin by just over 1.5 inches to allow enough clearance for the drill bit. So I took some 2x8 pieces of wood that I use to level my trailer tires when I camp, and some spare wood that I still had from when I cut the LE rib templates for bending the subskin, and I placed them on my work table. Then I tool a 3/4 inch thick and very long drill board that I had not used in a very long time, and placed it on top of the 2x's, giving me plenty of clearance for the drill bit. I also needed to make sure that the wood was placed directly under the wood to keep the unibit from severely marring the metal.

I mounted the bottom of the LE skin on the drill boards and clamped everything down. Here was the first hole, all drilled using my cordless electric drill. I went slowly and took time to clear debris from the hole to allow the drill bit to continue cutting. In the next pic you can see how much excess material I left between the edge of he hole and the traced panel line around the corner (about 1/16th of an inch or slightly more). Having gone through the entire procedure now, in hindsight I would have left less material to remove around the edges, because it took a lot of filing, sanding, and smoothing to get the fit just right for the panel. But at least you can definitely verify that this was definitely using a .5 inch radius:

Here is the clamping arrangement of the table and drill boards:

I had to adjust the LE skin a bit for the third hole due to the width of the 2x8 not being quite wide enough to drill all three holes. After that was done, I ended up with three pretty uniform holes:

Then came the cutting of the rest of the metal. I used my Dremel tool with a flex shaft extention and an EZ lock cutoff wheel. These have seemed to serve me pretty well in the past, and this time as no different. This is always nerve racking, however, because it is very easy for these 30,000 RPM cutting wheels to decide to grab the metal and completely destroy whatever you are trying to cut in a matter of split seconds. SO I mounted the actual Dremel tool on the shaft of one of my clamps that I intentionally mounted independently on the work table, so I could use both hands to control the flex shaft and the cutting wheel. this actually went fairly well.

Prepping for the cut. It tool several episodes of clamping, cutting, repositioning, and reclamping to put the metal in just the right spot to cut each of the 3 sides. Sometimes you just have to get creative and use whatever is around:

After cut number 1:

The goal is always to cut away from the line a bit to ensure you don't mess up the cut. IN this case the task was to remain inside the lines of the panel.

Repositioning and reclamping for the next cut:

And after the second cut:

And after the third and final cut. Normally there would have been 4 cuts, but since the existing hole was already there, only 3 cuts were needed:

Next came the task of slowly filing away the remaining material up to the lines drawn around the panel. I used a normal, fine tooth, straight flat file, and even my cut off wheel in a rather unique fashion that I have never tried before, to trim the corners and the straight edges as much as possible. Then I resorted to a 1/4 inch sanding drum with the Dremel tool to perfect the corner areas, and to blend them with the straight edges. A word to the wise - be very careful using the straight file, as it is very easy to create a ridge of metal or to cut too deeply if you are not paying attention. this is always an exercise in patience and in removing very small amounts of material and constantly checking the result to make sure you do not over-do it. I almost made that mistake with the cutoff wheel in one of the corners, but I think I averted the problem after smoothing the corner with the sanding drum. This next pic shows I am getting close but not quite there yet.

After finally getting the fit to be acceptable to me, It was time to fit the mounting flange for the panel by clecoing the panel to the flange in an upside down manner and using the panel to center the flange so that the flange mounting holes can be drilled into the skin. I have not had to deal with this sort of thing ever since I made my first flange in the Sport Air sheet metal class that I attended many years ago.  So everything was an adventure into the unknown. As long as you do a good job cutting out the access panel opening in the skin, the flange should line up exactly like it is supposed to. Mine was not totally perfectly aligned, but it was close enough for me.

I had to readjust my table setup again to allow a gap between the edges of the skin and the new access panel opening to allow room for clecoes to be inserted without interference from the wood underneath. Here is how I setup for that:

Once the panel is centered in the new access hole, I used a couple of cleco clamps to hold the flange in place and then started to drill the #40 rivet holes through the flange and the LE skin. Only the outer holes are drilled as these are the mounting holes that attach the flange to the skin. the other holes are for the nut plates that the panel will screw into. The larger holes are predrilled in both the panel and the flange to #30, and the panel is attached by some #30 clecoes to the flange.

I could not drill 5 of the holes as these are the ones that overlap the existing hole that I will need to fill in after this lovely task is completed. Here are the clecoes in the holes that I WAS able to match drill:

And finally, from the back side of the LE skin, it is a bit hard to tell from the pic, but I think that the fit of the panel looks even better than I thought it did. When this is finished, the flange will be mounted on this side, and the panel will be on the other side (reverse of what is shown now).

My next steps are to mount the LE back onto the wing spar for the 10 millionth time and reattach the subskin. I still have to decide if I want to trim the subskin away in these areas for the panels, or if I want to use the subskin as the mounting flange.for the panels. This would be relatively easy enough to do now that the flange mounting holes have been drilled into the LE skin. All I have to do is match drill them again into the subskin once it is mounted in place to the LE.

I have to figure all this out to determine how to trim the subskin to its final form. I also need to drill the rear rib flange to wing spar holes in the newly modified 408 rib. Then I will have to remove it yet again to debur the holes. This process just seems like it will never end, but at least I am making progress, regardless of how slow it might be.

An Exhausting Weekend at SportAir Workshop

So comes gthe end of my vacation week. What better way to do that than to attend another weekend SportAir Workshop held by the EAA at RedStone College near KBJC. This is a very well known School for Aircraft Mechanics. This time the class was for Composite Construction techniques, aka fiberglass, carbon fiber, and other materials used in aircraft construction. My main focus for attending this class was to determine what I can use to fabricate the fake machine gun farings for the leading edges of my wings. Many of the others in my class were from the boating or race car genres, and others were building aircraft completely out of composite materials by using plans and not kits.

This class, as with all of the other classes, provides invaluable information, and for the $350.00 price tag you need to soak up as much of it as possible. There are at least 2 or 3 more of these classes I intend to take in the future, including, welding, firewall forward, and maintaining your aircraft. These will come later on, but for now I will add this latest class to my existing list of attended classes, including basic sheet metal, RV construction techniques, and Electrical systems.

While there on Saturday Mike Rettig (attending the electrical class) and I stopped by the hangar where the builds for Bob Markert (RV8) and Sean Thomas wage on. Sean has now passed me up and is working on his fuel tanks. I got to see some Proseal action in progress, so that was good. I learned from him to use a technique where I will use a scale that can read in gram units to measure out the proseal by measuring the correct amounts for each of the two parts of this stuff, then mix together in a separate cup, then take a plastic bag and place the mixture inside it, and then cut abottom corner out the bag, and using it like a cake frosting decorator, squeeze the mixture onto an appropriate syringe, which I will then use to apply the proseal in precisely the areas that I need.

Bob Markert is still wrapping up some wing stuff and working on his fuselage. It is great to see both a completed RV8 (Jim gray), and Bobs fuselage under construction, all in the same hangar. I took some additional photos of Bob's planned parking brake mechanism, ELT mount, access door for back side of the avionics bay, and his static port assembly. One other item that I was not aware that he was going to add was a prefabricated removeable Smoke Tank, which I also intend to install on my aircraft. Jim Gray also has this same tank for his aircraft, so I will have lots of knowledgeable folks to ask questions about all this when the time comes.

First pic is of Bob's Fuel Pump assembly. taken from the front of the firewall looking down from the top. The issue with this little assembly is about the tight space with which to make bends in the fuel lines. Bob spoke about providing bends in the line to provide some flex capability, which apparently does not exist if the lines are left too straight. Not sure I understand all that yet, but in time I will I am sure. Wow, those sure are some tight 90 degree bends.

Next shot is of the parking brake assembly. That is all I know about it at this point, but I plan on putting one on my plane so I will be paying close attention to how Bob does his. This was taken from the front again looking rearward:

And now from the cockpit side:

Next is the smoke tank. There is another version with a smaller tank that I think that Sean said he was going to put in his plane, and I may end up doing the same, but this is a typical full size tank that is used for those that are so inclined.

Next is Bob's Static source plumbing in the back of the fuselage. I ahve the fittings for all this already. Just need a fuselage to mount them on!

the last two pics show the Adel clamps and nuts/bolts used to atach everything to the bulkhead.

NOw on to the sport air composites class. I managed to get a few pics of some of the activity today. We learned how to use a bagging technique for vacuum forming that allows the parts to cure more quickly and also provide a much better finish by extruding all excess epoxy from the parts during the process. THis was very cool to witness, but it does involve some tools and know how in order to do it correctly.

First is instructor Scott Vanderveen getting ready to place some NACA vents fabricated from clay molds under the vacuum. There were about 14 of us in the class, so doing all of these at the same time presented some challenges.

The blue plastic is a self adhesive vacuum bagging vinyl material with some double sided sealing tape applied to the bottom layer. The red stuff on top of each part is a perforated teflon coated release material that allows excess epoxy to be extruded and separated from the parts.

Next is a heat pamp area and our primary working table where we made all are creations come to life. For the class you will make a canard airfoil section with a spar cap and foam core, a polystyrene foam and fiberglass sandwich that later becomes a partial wing spar assembly, and the naca vents shown above.

Next is the modeling clay that is used to form molds. You can apparently get this from Hobby Lobby locally. Sounds like time for a trip to the hobby store.

Next is a pic of what I think is just bed batting material that you can get from Joanns or any fabric store. this is used to help maintain a constant temperature while under the vacuum.

then the top layer of the bag goes down, and theother side of the tape, which actually resembles the clay or caulk, is exposed:

Then some pics of the vacuum pump assembly and process:

And finally the pump turned on the vacuum being applied:

And lastly, once the vacuum started working we had to try to massage the top of the bag around the parts. Mine did not turn out so well because the vaccum did not apply evently around the part and I could not get the wrinkles in the bag totally removed.

what I got most from this class was the confidence to be able to to acquire some supplies and create some mock ups from which I can fabricate my own machine gun composite parts. It will be a lot of fun, albeit time consuming, to fabricate everything and seee how it turns out. Totally worth while and highly recommended if you are even thinking about building an airplane.

To be continued.......

Catching Up After a Long Dry Spell

Man, this year is just flying by. Wish I could say the same for my project. I have been overtaken by events over the past several months, and the result is that not much has been done on the build. It started with the decision to get my tailwheel endorsement, followed by attending the Sport Air Electrical workshop earlier this month, and then I got the hankering to do a bit more flying for a while. SO I also checked out in the club C-182 and C-172s. Then work got in the way - you know, that pesky thing that allows you to embark in this crazy activity known as "flying." Unfortunately in my line of work October means huge deadlines for software releases that have been worked on for months, so one has to do what one has to do to get to the finish line.

Then I had a couple more revelations that have served to get in the way of actively working on the project. The first was an opportunity through the company I work for to take part in a weight loss program called Slim-genics. For far too long I had let my weight get the better of me, adn now it is slowly taking its toll on my ever-aging body. So I took a huge plunge and dove in head first and I am now about 4 weeks into this program and have lost almost 30 pounds. The ability to continue holding a medical certificate and continue to have the privilege of flying where ever I want to is a very strong motivator for me to get and stay healthy from now until the end of my days. Unfortunately this also required a time commitment to do all the things that are necessary to change bad habits and get back to a healthy life style. SO other things must suffer a bit while I take care of the truly important stuff. ONly other thing I will say about the program is that IT WORKS! I had to go buy a new smaller belt today and new clothes are not too far behind. Looking forward to "getting smaller" in the window. (reference the movie Apollo 13 for the pun!)

Then I decided to take the opportunity to fly my very first EAA young eagle this weekend. His name was Logan and his Dad's name was Mike. IT turned out to be a bit if challenge to make this happen, since we had two snow packed systems roll through the Denver area last week, and unfortunately this set the stage for a heavy Frost on Saturday morning. I was out at KAPA at 0600 in 17 degree temps to provide enough time to preheat and preflight the airplane and reposition up to KFTG where the YE rally was taking place. The sun finally warmed things up enough for me to depart in a C-172 at about 1000, and I was able to catch one of the last flights with Logan and his Dad before it eas time to turn around and head back to home base. That ride was a lot of fun. I thoroughly enjoy introducing aviation to the young peopel in hopes of lighting a spark in some of them that may someday result in them pursuing the same dream as I.

Then, as if that was not enough, I also decided that it was time to dust off an old project I had started a few years ago when I had a hankering to put together a miniature christmas village, complete with christamas trains and and little holiday scenes being played out by miniature people in a different place and time. I first caught this bug after discovering a system provided by the Woodland Scenics company, which specializes in products to create such displays. They have everything from specialized plaster products to fake trees and rocks, etc., and they have a series of how to videos that take you through the process step by step.

I became acquainted with all this when I helped my oldest son with a High School class project that involved creating a midieval scene from the Roman empire that involved a castle dn draw brige and such. That is when I got the idea for the christmas village. I made it as far as getting the train track laid out adn a basic idea for the village that I wanted. I stopped working on it after a lot of detail work on the tunnel was completed, with a bit more left to do. It has sat in a corner of my basement gathering dust ever since, so I figured it was high time to try to get this project moved along for this upcoming holiday season, so I am now neck deep in that effort.

Needless to say, this does not leave much room for working on the plane. I will say that the Sport Air Electrical class was just awesome. Fellow RV-8 builder Scott Larsen also attended. In that class we learned how to attach a variety of different crimp connectors, including a BNC connector to some RG58 antenna coax. Then we also got to wire up and solder an actual Phone and Mike jack for a PPG intercomm system, and the acid test was whether you could plug in a headset to the actual intercom unit and hear yourself speak over the microphone. Mine worked just fine. The final project was one that emulated an on/off nav light circuit and an adjustable interior cockpit light circuit. Again, mine worked as expected. I cannot say enough how valuable all of these Sport Air classes are for learning basic skills tht can be applied to the airplane project. The class was taught by Dick Keohler, whos is also one of the folks that presents a variety of electrical how to hints in the EAA Hints for Homebuilders series of instructional videos. Dick is a great guy and a great instructor.

Then there is all the current events that have unfolded within the EAA organization over the past several weeks. Recently appointed leader Rod Hightower resigned and President and CEO of EAA, sighting family relocation concerns as the reason. There are a lot of long-time EAA members that are not happy at all with this transition, adn it seems the root concerns are centered on EAA losing its focal point on Homebuilding, Experiementation, and Innovation, to a much more all-inclusive aviation audience adn community.

Dick Koehler also told us some stories about the massive re-org that took place at EAA after Hightower took office, adn some of shady things that occured behind the scenes that seems to have negatively impacted a lot of really good people. I was very saddened to hear some of these things, as my experience with all things EAA up to this point has been largely positive. The most disturbing thing that Dick told us was that the traveling Sport Air classes that I was attending may very well be the last ones to be offered at satellite locations forever more. EAA is sighting financial issues as the reason and apparently was moving toward a philosophy to conduct the classes at Oshkosh about once per quarter, instead of traveling to a variety of different locations throughout the country. This was truly disheartening to hear.

These are truly trying times for EAA as it struggles to determine it's niche in the rest of the aviation world in this present day environment. Now that a new leader is being sought, I hope that the integrity of the namesake for the Experimental Association will be preserved as we move forward in the vast world of all things aviation.

So, enough for now. Hopefully the remainder of the year will be a bit more serene, and a little less hectic. And then, true to my past experience thus far, I will probably find the time to start working on the plane again just about the time there are sub-zero temperatures in the garage. That just seems to the be the way of things for me and this project. The wings will get done - - eventually.

Feb 19and 20 2011 - Attended EAA Sport Air RV Assembly class

John Brecker was the instructor for this class which was held at the RedStone college of Aviation up near Rocky Mountain Metropolitan Airport in Broomfield. Several members of the RV List Yahoo group that I belong to were in attendance. My main goal for this class was to gain some experience with rolling the leading edge of the practice kit, which basically resembled an airfoil section of a control surface such as an elevator or an aileron. Had a lot of fun meeting new folks just getting their feet wet with the whole process, adn some that are still dreaming of the day. I'll have some more pics and info about the class in later posts. It has been a fairly eventful week for the build, so I want to get that updated for now.

Here are some pics of the completed practice kit:

A couple of aluminum sheets, two ribs, 4 stiffeners, and a forward spar. Leading edge is rolled using a 1 inch broom handle adn duct tape.

This is a pic of a back riveting technique that is used on the trailing edges of some control surfaces that use a separate top and bottom sheet, and a wedge that is sandwiched in between the two sheets. Since the rivet gets inserted at an angle, it is not possible to get a typical shop head out of the other end of th rivet when it is set. Instead, the factory or flush head gets taped to the skin, and the skin goes on top of the back rivet plate, and then you take the flush rivet set in the rivet gun and attempt to set the shop head. The result is show below - the shop head only partially fills the dimple in the skin. This is normal, but a bit unseetling to those of us that have been setting rivets for a while, that know what a good shop head is supposed to look like.

Class Partner Gets to Keep the Prize

This was my partner in the class. He had started working on his private license many years ago, but like many others, he ran out of money after soloing. He told me that the next time he starts to work on it he is going to finish it all the way. It was very interesting to see that several people in the class were not even rated pilots (yet)!
As much as I wanted to take home the completed project, I felt that it would be better off remaining in the possession of someone that is still trying to realize the dream of aviation, even if it means having a bunch of riveted metal parts stuffed out of sight in the corner of a garage for a while. Perhaps one day it might just be responsible for the creation of one more pilot, or even better yet, another airplane builder! I wish him well in his pursuit of flight.

EAA Sheet Metal Sport Air Class Practice Kit

Here is the project that we built in the workshop. The inspection panel on the right has 3 screws that are secured with 3 nutplates that are riveted to the underside of the skin. The trim tab on the bottom is hinged with piano wire.

Finally getting started!!

So what has happened since my last post?

• Attended a 2 day EAA Sport Air Sheet Metal workshop
• Went to my buddy Ron's house to see his workshop and almost completed empennage of his RV7.
• Spent hours researching primer on the Van's Air Force (VAF) website
• Made my decision to use self etching primer, instead of alodine, at least for the internal priming
• Repaired one of my work benches to correct a bow in the table top
• Officially started working on the horizontal stabilizer on 10-6-2009 - 3 hours last night and 2 hours tonght for a total hobbs time of 5 hours so far.

Details from the above events follow:
For the sheet metal class we built a section resembling an elevator, complete with an inspecton panel and a trim tab. I will upload pics of the fnished project, but I need to pull them off of my cell phone memory first. We had to work in two-person teams, and so only one person got to take the project home with them. I let my partner keep the project, because he had not yet started on a plane yet, and he needed something to allow him to keep dreaming about it. I knew I had the real thing waiting for me at home, so I was OK with giving the project piece to him. The only complaint I had about the class was the time constraint to finish the project. We had to work extremely fast as a team in order to finish it on time.
Seeing Ron's empennage was also a huge plus for me. He showed me his tail pieces, showed me how his workshop is set up, and talked to me about some things to watch out for in the plans. He was finishing up the left elevator, which also contains the trim tab. Ron also attended the workshop that I was at, except he was in the composite class, working with fiberglass and resin, which you need to know how to do to make landing gear fairings and a host of other things.
Primer wars......alodine, acid etch, epoxy-based, self etching, or nothing at all? Those are the choices pretty much. I talked to a rep from Sherwin Wiliams - he even sent me some DVDs, one of which was an entire paint process from a Gulfstream facility in Houston, TX. They showed how they strip, prepare, apply corrosion treatment, prime, and paint a Cessna Citation - what a process! I decided on self etching primer instead of alodine and epoxy primer after finding a post on VAF from a guy that had made a test panel with about 7 different types of primer solutions, including self etching primer. The main issue about this is if the self etching primer really acts as a good anti-corrosion barrier for the metal, with some arguing that the primer actually soaks up moisture instead of repelling it. The guy with the test panel was an employee of a paint company who took the panel to various trade shows, and then finally set it outside in the elements where it was rained and snowed on for about 8 years. The result - all of the primed solutions, including the self etching primer, had stood up well. This was the information I was looking for. So I bought a quart container of NAPA TE504 self etching primer and a gallon of the TER 514 catalyst/activator (not the same as the NAPA 7220 spray can stuff- the stuff I bought is the good expensive stuff that must be mixed and sprayed from a gun). Just to give you an idea - 1 QUART of the primer and 1 GALLON of the Activator set me back about $200.00. Not cheap for sure......
The first of the two work benches I had built unfortunately ended up with a small bow in the table top as a result of bad wood that I used for the frame. Several shims and repositioned cross braces later, the table top is now relatively level - so that problem is resolved.
It's official! October 6, 2009, I actually started on the rear spar of the horizontal stabilizer. This involved a lot of hole drilling and partial fabrication of of some thick reinforcing bars. Priming parts and riveting them together is just around the corner... Pics and more info in the next post.

Paul I P51 Paint Scheme - NICE!

So here is Paul I - Founder of EAA Paul Poberzny's personal aircraft. It is P-51 mustang (Actually I think the museum history points out that this aircraft went through some changes in designation frm an F-51 to a P-51 and back to an F-51 again. Anyway, this is very close to the paint scheme I have decided I want use for my aircraft - except for the yellow. If any of you have suggestions about the color for the nose,OTHER THAN yellow or red, that would pop well with the sky bue and the gray, then letme know. Oh, the nose art has also been decided upon, but I am going to keep that to myself until te project is completed to keep it a surprize.
I'm currently trying to settle on a primer solution/method so I can begin the tail construction. There are many different methods to choose from,which makes this decision all the more difficult to make. Epoxy or Etching primer, anodizing or leaving it all alone to save weight - UGGGHHHH!
Anyway, I am scheduled to attend a sheet metal class up in Broomfield, sponsored by the EAA, during the weekend of Sept 12 and 13. The more practice I can get, the better it will be for my project. Picked up some blue and gray paint that closely matches the color on Paul I, and I will use this to finish the paint job on my tool box. Matching plane and toolbox - what a concept!