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  #1  
Old 02-25-2018, 09:22 PM
ZachMiller ZachMiller is offline
 
Join Date: Nov 2017
Location: Dallas, TX
Posts: 26
Default RV-7 Zach's #74012

Hello all,

I'm relatively new to the forum, having only used to to purchase a few things thus far. I've been lurking for quite awhile and have nothing but positive things to say about the wealth of information here. I've recently started an RV-7 and will be using this to help document the build. I also intend to put this on my own site, which is why it reads a bit more like a story. I've got a bit of catching up to do, but all I've got time for tonight is an introduction. The awful weather in North Texas has finally broke and I need to prepare for my Night Flight lesson tomorrow. Stay tuned for the build and lots and lots of questions, I'm sure.

That said here is the first post (well, second post now I guess)

Zach
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Zach Miller
RV-7 Empennage
Donation made Dec 2017
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  #2  
Old 02-25-2018, 09:23 PM
ZachMiller ZachMiller is offline
 
Join Date: Nov 2017
Location: Dallas, TX
Posts: 26
Default Introduction

Hello all,

I’m starting this log to document my build of a Van’s Aircraft RV-7. This log will serve as a record of my build for my purposes and to prove to the FAA that I’ve built my 51%, a forum to ask the many questions I’m sure I will have, and, hopefully, a reference for future builders to use to avoid my mistakes. But first, here’s a little about me.

As should be evident, my name is Zach. I live and work in the Dallas area. I’ve been an aviation nerd for as long as I can remember. Growing up I tinkered with anything I could get my hands on and loved spending time in the garage figuring out how everything around me worked. Because of this, I decided at some point in elementary school that I was going to engineer airplanes. About a decade later I graduated from Texas A&M with a degree in Aerospace Engineering. I currently work in Liaison Engineering, developing repairs for whatever flies in broken or corroded. I spend a good portion of the day on the hangar floor, on aircraft, and working directly with the aircraft mechanics. I’ve had a little bit of work experience with just about everything aviation related (except piston engines, oddly, so perhaps a turboprop would be best in my RV), much of which I’m sure will be useful throughout the build. That said, I just tell others how to repair things… Prior to this build I have never bucked a rivet, but I can spout off from memory the various rivet and Hi-Lok hole sizes and tell you the acceptance criteria for a rivet bucktail (among other things). So I guess I think I know what I’m doing, but only in theory…

About a year ago I had a bit more free time than I needed and found myself on the Van’s Aircraft website. Well, I got looking at the sleek airplanes, high performance numbers, and prices that were within the realm of plausibility and, well, got bitten by the bug. I’m sure we’ve all been there.

The time was ripe to start another project. With no wife to ask permission from (and the amount of discretionary income that comes with no wife) I decided right away that there was an experimental aircraft in my future. The research began. I viewed every page of Van’s website, most more than once. I scoured Van’s Airforce. I compared every model. I even thought ‘Hey, maybe there’s a better experimental aircraft than Van’s out there.’ I searched the competition, from rag and tube to wood to metal to plastic. And I came back.

I’m a bit of an adrenaline junkie and speed freak. I spent most of college racing motorcycles and have the scars to prove it. I’ve graduated to cars now and love to take my Subaru out for the occasional track day. So the non-aerobatic aircraft were never in the picture. That left the 3, 4, 6, 7, 8, and 14. I’d like some 2 person touring ability, so the 3 is out. The 4 and the 6 essentially have upgraded models, so they are out. And while the 8 is cool, I much prefer the fastback look of the side by side models (unpopular opinion, I know). Plus, I’m used to side by side and it is a much better configuration, in my opinion, for touring. So that left the 7 or the 14. Ultimately I couldn’t see spending the extra money upfront and the extra fuel for years to come on the 14. Perhaps I will sit in the 14 someday and regret my decision, but I’ve got enough life left in me to build 3 or 4 more airplanes. I’ll cross that bridge when the day comes.

It was decided then. I’d build an RV-7. Only one issue remained. I didn’t have my private pilot’s certificate (well, technically still don’t as of this writing). In fact, I hadn’t even started. Being an aviation buff, I always told myself I would, but didn’t have the time or funds in college and hadn’t gotten around to it post-college. I thought to myself ‘Who in their right mind would build and airplane without even being able to fly it? I might not even enjoy flying?’ (As an aside, no offense intended to those of you who have started building an airplane before starting your private. The previous quote is exactly what ran through my head when I decided to build the RV-7. I’m too much of an engineer who needs perfect order, cause and effect, to start building an airplane I couldn’t yet fly.)

It was simple. I’d start training and then I’d start building. The next week I got in touch with the local flying club. I’d already take ground school a couple years prior, so there were several familiar faces at the club. I took my FAA written (required prior to training at this club), got my 3rd class medical, and started flying. As of this writing I’m closing in on my check ride. Only night flying and a couple of those cross counties remain and I will be ready. It’d be easy, if the weather would cooperate.

My plan for the build is this: an RV-7 taildragger, sliding canopy, powered by a 180-200hp Lycoming. I’d love something that burned Jet A, but can’t seem to afford anything with ‘turbo’ in the name and Diesels are either too pricey or not quite there yet. It’ll probably have some brand of EFII and as much glass as I can bankroll on the panel. I got years to decide on the details. It will be primed on the inside and painted on the outside (I’ve seen enough corrosion horror stories for this to even be a question). Other than that I’ll keep it light and simple.

That’s enough of an introduction. Stay tuned for a look at my shop preparations, tools, and, ultimately, an airplane build.

Till next time,

Zach
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Zach Miller
RV-7 Empennage
Donation made Dec 2017
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  #3  
Old 02-25-2018, 09:34 PM
seward747 seward747 is offline
 
Join Date: Jan 2005
Posts: 136
Default

Thanks for the intro Zack. Sounds like you've done a rather thorough analysis on which model to go with. Enjoy the journey, good luck on the project and your PPL. We'll be on the lookout for future progress reports.

Doug
Seattle area
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  #4  
Old 03-04-2018, 08:24 PM
ZachMiller ZachMiller is offline
 
Join Date: Nov 2017
Location: Dallas, TX
Posts: 26
Default Preparations and Tools

This will likely be a continuously updated topic, but here is a quick rundown of my current tools and building accommodations.

As previously mentioned Iíve always been working in the shop and turning wrenches. Since high school Iíve been collecting tools and been out in the garage using them. For about 7 years throughout high school and college I worked as a machinist, so perhaps that cultivated by love of quality machine tools and heavy iron. I also quite enjoy turning chunks of metal into smaller, more precise chunks of metal (and chips). Therefore I started collecting. Upon graduation from college I had roughly a 1 car garage worth of tools. One year after college I had a 2 car garage worth. When it came time to look for my own house a dedicated shop was a high priority. I ended up purchasing a house with a 2 car attached garage and an additional 850 sq. ft. shop. Iíve expended quite a bit of effort improving it. Iíve poured epoxy on the floors, painted all the walls white, added extensive 220v and 3 phase wiring, and installed LED lights throughout. This is where the RV will be built.

As far as tools, I was in pretty good shape prior to starting the RV. I quite love my tools, so I apologize in advance if it seems like Iím bragging on my collection (and Iím sure it pales in comparison to some of you readerís collections). On the machine shop side of things (not particularly useful for aircraft building) Iíve got a 14x40 manual metal lathe (a nice Mazak) and a small home built CNC mill (another long, long project that will probably never truly be finished). A Millermatic 211 handles my MIG welding needs and a Syncrowave 250 handles the TIG and stick welding. I really only pretend to know how to weld (I wouldnít trust my welding on an aircraft). Besides the big stuff I have quite a bit of support equipment, including a 3 x 36 belt sander, pedestal grinder (currently with 1 stone wheel and 1 Scotchbrite bristle disk), a large 3-phase drill press, and a 60-gal twin pump compressor. Many of these tools, particularly the support equipment, will be very useful throughout the build.

On to the aircraft tools. Just prior to getting the empennage kit I began looking for tools. From the experience at my job I roughly knew what specialized tools Iíd need. Tools like clecos, a rivet gun, bucking bars, quality snips, various forming pliers, an angle drill, and a pneumatic squeeze would be essential. I posted a feeler on Vans Airforce just to see if anyone had some of the more specialized tools for sale and quickly got a reply from a guy whoíd finished building and was looking to get rid of most of his tools. Perfect. After a bit of back and forth I ended up purchasing practically all of the mechanical tools. I did get a few duplicate tools, but I didnít mind. Did I mention that I like tools? Here was the initial haul.



Everything here, except the pneumatic squeeze, came from the same person. He also had a pneumatic squeeze, but the purchaser of his aircraft wanted to buy it. I purchased the squeeze in the picture off eBay for quite a deal. A week or so later, the guy I purchased all the tools from contacted me that the buyer of his aircraft did not, in fact, want the squeeze. So I bought that one too, along with more sets and dimple dies. Iíve since sold the squeeze I got off eBay to an RV builder in my flying club. Apparently owning 2 pneumatic squeezes is where I draw the line. Over the past few months Iíve also built up a few of the smaller items that I needed, such as abrasives, more clecos (up to about 700 3/32Ē now), and hand tools.

With the tools sorted out I was almost ready to build. The only other things I needed were a couple sturdy workbenches and a small paint booth. I live in North Texas, so the weather outside is almost never adequate for priming. Therefore I want a small area of my climate controlled shop sectioned off for spraying. I built two (for now) standard EAA1000 tables. They were easy but a bit time consuming. The paint booth went together relatively quickly. It is basically a 4 x 8 room framed like a house. A 2 x 8 bench stretches along one side covered in chicken wire. The floor is made from two layers of heavy masking paper bought from one of the big box home improvement stores, simply stapled to the bottom. The frame is then wrapped in plastic. On one side are two 20Ē box fans with HVAC filters providing positive pressure. On the bottom of the outlet side are two more filters to stop dirt from getting in. The exhaust is directed out the garage door. The door to the paint booth is just a wooden frame with plastic stapled to it. It just gets shoved into its opening. A couple LED flood lights up top brighten up the inside. So far the booth works better than expected. There is no Ďfogí inside while spraying and very little overspray makes it out. There is a surprising amount of positive pressure considering it is powered by two box fans.
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Zach Miller
RV-7 Empennage
Donation made Dec 2017
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  #5  
Old 03-04-2018, 08:29 PM
ZachMiller ZachMiller is offline
 
Join Date: Nov 2017
Location: Dallas, TX
Posts: 26
Default Preparations and Tools Continued

Hit the character limit... Last post continued:

The raw materials:





Finished paint booth from the outside, donít mind the mess:



Exhaust side:



Intake side:



Spraying table:



Back at the work tables, I decided to add a simple back riveting plate to one of the tables. I took a piece of ľĒ x 4Ē steel plate I had in stock and cut a 12Ē long piece. I rounded the corners to R.25 and added a countersunk hole in each corner for a wood screw. Then I took an old, chipped end mill from the CNC mill and chucked it up in a hand router. It definitely wasnít the right tool and had a tendency to burn the plywood top, but it got the job done. It was a scrap endmill to begin with, so no harm done. Iím woefully lacking in wood working tools. Iím also somewhat of a poor woodworker. Why mess with dead trees when there is perfectly good metal? Anyway, after cutting the recess I screwed the plate to the table and covered both tables with the heavy masking paper I bought for the paint booth floor. A quick trace with a sharpie around the back riveting plate to make it easy to find when needed and I was all set.



Lastly, I purchased a large heavier duty shelving unit to hold all the aircraft parts. I much prefer the ones with wire shelves as the shelves do not accumulate dirt and dust and let a little light through. Here is a shot with the empennage parts on it.



My shop is in disarray at the moment. With the two new tables there is just a little bit too much in the shop. Iíve got an unrelated project to complete and get out of the shop and a motorcycle to get rid of, then a good rearrange and cleaning is in order. But for the time being Iíll build in the little corner Iíve sectioned off.
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Zach Miller
RV-7 Empennage
Donation made Dec 2017
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  #6  
Old 03-04-2018, 08:34 PM
ZachMiller ZachMiller is offline
 
Join Date: Nov 2017
Location: Dallas, TX
Posts: 26
Default

Quote:
Originally Posted by seward747 View Post
Thanks for the intro Zack. Sounds like you've done a rather thorough analysis on which model to go with. Enjoy the journey, good luck on the project and your PPL. We'll be on the lookout for future progress reports.

Doug
Seattle area
Thanks! I'm quite looking forward to the build. There should be a bunch of posts in the coming week as I attempt to catch up.
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Zach Miller
RV-7 Empennage
Donation made Dec 2017
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  #7  
Old 05-03-2018, 07:44 PM
ZachMiller ZachMiller is offline
 
Join Date: Nov 2017
Location: Dallas, TX
Posts: 26
Default Finally a Private Pilot!

After about 9 months, 55 flight hours, and around $6,000 (estimating, I haven't added everything up yet) I am finally a private pilot. Working around the runway closures at my base airport, I took my check ride this past Monday on a typically gusty north Texas day. It wasn't my best flying, considering the conditions, but I passed!

With training done I will have quite a bit more time and money to work on the RV. I'm still working to get this thread caught up with my actual progress.

Zach
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Zach Miller
RV-7 Empennage
Donation made Dec 2017
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  #8  
Old 05-03-2018, 08:04 PM
ZachMiller ZachMiller is offline
 
Join Date: Nov 2017
Location: Dallas, TX
Posts: 26
Default The Empennage Kit

Towards the end of 2017, after I had decided to for sure build an RV-7, I decided it was time to purchase the kit. My workplace essentially shuts down for two weeks during the holidays, so I’d have all that time to start building. My plan was to order the kit from Van’s at the beginning of December to have the kit in time, however I also kept an eye on Van’s Airforce for the possibility of getting a ‘used’ kit. For me to purchase a used kit it had to meet two requirements: be local(ish) and almost completely untouched. I didn’t want to inherit someone else’s bad workmanship.

At some point in November I got lucky and a nearly untouched empennage kit came up in Houston. I believe only 6 rivets were installed. Houston is about a 4 hour drive from where I live, but this is the enormous state of Texas; 4 hours of driving is a reasonable day trip in these parts. Even better, I’d be headed to Houston to visit family for Thanksgiving, so that would be a perfect time to take a look. So I got in touch with the seller and arranged a meeting.

On the way to look at the kit I got a disheartening text. The seller was pulling together all of the kit and found some corrosion on a handful of the parts. I gave him a call to discuss it and it sounded relatively severe. I decided to take a look anyway, after all I spend about half of my time at work fixing corroded aircraft parts.

Upon arriving, I took a good look at all the parts. The parts had been stored with the blue film still on which is notorious for causing corrosion. Additionally, they were stored in a non-climate controlled garage, however the seller did assure me that they were not flooded during the recent hurricane. Taking a good look eased most of my concerns regarding the corrosion. A majority of the corrosion was very superficial, less than a thousandth of an inch deep. It was mostly powdery white surface corrosion, with some pitting and filiform corrosion. I’d estimate that 15% of the parts had corrosion, although most of it was only along the edges in localized areas. Around half of the skins had corrosion, although it was slight.

Taking a closer look revealed two parts that I wouldn’t feel comfortable installing: one of the HS609PP Horizontal Stabilizer Spar Reinforcements and the WD605R1 Elevator Horn Weldment. Being corrosion prone extrusion, the HS609PP had visible intergranular and pitting corrosion. Perhaps it could have been removed and saved, but this is highly critical structure and I’m building a new airplane; it just wasn’t worth the risk. This part was nearly $100, however. The WD605R1 had some of the powdercoat bubbling from rust underneath. After ordering a new one, I removed the corroded area from the old one and discovered that it wasn’t as bad as it looked. I’m positive the original one would have been fine, but the replacement was fairly cheap. With the replacement parts I also ordered the practice toolbox and control surface kits.

To give an idea of the scale of the corrosion, here is the absolute worst spot on the skins. As mentioned it is almost entirely along the edge.



Here it is after rework (I may call it ‘blending’, but it just involves using Scotchbrite or fine sandpaper to remove the corrosion and give 125 RHR or better surface finish):



Here you can see I’ve drawn a ¼” x ¼” grid on the blended areas and measured the remaining thicknesses. I measured with a properly calibrated micrometer. Even that nasty looking corrosion only required .002 material removal to completely remove the corrosion. Since the original sheet thickness was .001 over nominal, I only ended removing .001 from the designed thickness (.019 remaining thickness on a .020 skin).

How can I be sure that this is acceptable? There are many methods that are used in the industry, however the easiest and safest is simply to look at the allowable tolerances that the aluminum sheet had leaving the factory. These are contained in a specific ANSI document. For this sheet thickness I believe the tolerances were +/- .002 (although I’m saying that from memory and it has been awhile, it may have been .0015, it varies depending on the thickness of the sheet). That means a brand new sheet could be as thin a .018 leaving the factory and still be perfectly acceptable. Therefore my blend of .001 is acceptable.

The sheet thickness tolerance isn’t extremely large; often it is necessary to justify more than a couple thousandths material removal. For parts that aren’t extremely critical, I would hesitate to remove 10% of the material thickness (which is only .002 in this case, but increases for thicker sheets) without doing any actual numbers-on-paper analysis (especially if it is only locally removed). 10% is sort of standard in the industry for sheet metal parts, although it can vary depending on the criticality of the structure. Often times more than 10% is allowed by the OEM manuals for certain structure. Any greater than 10% or if the structure is extremely critical, I’ll want to develop the worst case loads on the part and ensure that the area I’ve reworked will not be the first thing to fail. If it is the first thing to fail, I’ll have to show that it still meets the 150% ultimate load requirement. There are many methods to do this, but I won’t bore you. If I ever have to get this in depth on my RV build, I’ll probably just reorder the part. Van’s is great about replacement parts. You oftentimes can’t find all the parts for the big airplanes.

What about the cladding, you ask? I’ve worked in the industry for a while. I’ve seen hundreds of corroded parts, maybe thousands. I have to find out what the part is made of to remake or repair it, so I’ll know if it is bare or clad. A majority of the corroded parts I deal with are extrusion (which is never clad), but for sheet metal parts the bare/clad doesn’t seem to make a difference. I see just as many clad parts that have corroded as bare parts. I can also find no rhyme or reason as to why the OEMs pick clad or bare for certain parts. Perhaps there are more clad parts on aircraft and that explains it, but my opinion is this: if the conditions are right to form corrosion, the cladding may help for a while, but the corrosion will win. I believe the best thing is to apply the best line of defense you can: a corrosion inhibiting primer. If someone has some actual testing data to prove me wrong, please provide it.

I should also note that after rework I apply Alodine (from a pen) to the areas where I have removed the cladding. Cladding is very good for preventing ‘flash’ corrosion, which can happen surprisingly quickly on certain aluminum alloys. So cladding is certainly useful when parts are sitting around unprimed, I’m saying that once the parts are primed it becomes nearly irrelevant. Don’t get me wrong, there are plenty of 50 year old aircraft flying with unprimed, unclad aluminum. And there is no process to end corrosion once and for all. I like having as much insurance as I can get. If I can have cladding, conversion coating, and primer then great, but I’m not going to shed a tear if the cladding gets removed (and I’m also not planning to Alodine, other than touch up, due to the harshness of chromates and the environmental concerns).

Take everything said here with a grain of salt. This isn’t a complete guide to reworking corroded aircraft parts, I’ve left out about 99% of what I know of it and there is so much that I don’t know. Use your own sound judgement and call Van’s if you don’t feel 110% comfortable with the structural integrity of your parts. I’m not advocating anyone else do anything written here and am not responsible if they do.

In the end, removing corrosion is a lot of work. After accounting for the cost of the parts I replaced and all the extra work, I probably paid too much for the kit, although it was certainly cheaper than new and I did get it cheaper than originally advertised due to the corrosion. I suppose I did also save shipping and all the hardware was very neatly organized in nice containers. So who know, maybe it wasn’t that bad of a deal after all.

Whew, I can get to the actual building now.
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Zach Miller
RV-7 Empennage
Donation made Dec 2017

Last edited by ZachMiller : 05-03-2018 at 08:06 PM.
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