RV7-Factory

When I decided to create a builders log site, I knew I needed a simple little logo to identify it. A fellow CAP member, pilot, and friend has some graphics skills. So I asked him if he had any ideas. He came up with the above. I like it. As you can see in your browser, it shows up as the favicon next to the address too. Simple, clean, and fitting. Thanks Matt!

On another note, Matt is looking for a FLYING job. He is instrument rated with a commercial pilots certificate in both ASEL and AMEL aircraft. He has 1000+ hours total time and a very professional pilot. If you have or know of any jobs, please use the email link in the upper right corner to let me know. He will fly for food! 😉

Those around the RV world know the primer debate is a hot one. There are MANY general aviation aircraft in service that have been around a long time with no primer…but they were not hand crafted by the owner either.

I have chosen at this point to prime all the parts internal to the airframe. I know that currently I do not live near a salty coast or a highly wet climate…but that may change in the coarse of life. Of course at this point it feels like I do considering the very wet spring we have had lately. I do live near the Great Salt Lake, but again, it seems to evaporate and disappear rather than linger in the air. So the next decision is which primer to use.

I decided on the Dupli-Color Self Etching variety. I have had great success with it on other projects. It takes care of the etching and is very durable. The other bonus is that it comes in cheap spray cans. The other point is…I do like the color. Kind of a throw back to the old bombers of WWII. It also seems to get good reviews on VAF. The other rattle can variety that gets good reviews is the NAPA 7220 Self Etching. It is grey in color, but has the same durability.

Once all the edges/holes were deburred, I scuffed the parts with a maroon scotch bright pad. Good thing I have a local source as I am sure I am going to burn through these fast. I then cleaned all the parts with Denatured Alcohol and let dry. From that point on, I wore nitrile gloves so to keep any oils from the parts. Then I hung them from my overhead shelving racks in my garage and sprayed.

I did find one item of interest as I was spraying. It was my method of the hanging the parts. It seems that hanging them vertically is not very effective and results in a lot more over-spray. I think I may have sprayed more on the floor than on the parts. I think for the next round of parts, I will rig up a spray tray out of chicken wire or some other method of being able to set them horizontal so that I can better place the parts for maximum coverage and minimal waste.

Otherwise, they look great and are now ready for assembly. I will let them rest for a few days to simply make sure the paint is good and cured and then get to it. Those gold plated rivets will look really good against the green. 😀

After work, I was able to get started on deburring the HS skin rivet holes.  First I removed the vinyl coating completely from the inside of the skins and then only over the rivet lines on the outside. Lots of debate on the right thing to do, but I chose to retain it as we are in a dry climate and I want to protect it as much as possible until paint. As for the holes, basically I took a 3/16″ bit and spun it in my fingers in each hole. It knocked the burrs right off and it does not take to much material with it. There has been a large amount of discussion as to what is and is not too much deburring. I was pleased with the outcome and feel it is just right.

After getting the left skin done, it was time for my two boys pack meeting. They are progressing well in Cub Scouts and Webelos. Their shirts look like hard working cubs…completely covered in patches.

Once pack meeting was over, and the three kids were tucked in bed, it was time to see what else I could get done. I got the right skin deburred, then deburred the edges of both skins to a non finger slicing smoothness. I had not completed the setup of my DRDT-2 Dimpler to date. I needed to bolt it down and wrap the support table with some scrap carpet. No time like now, so I knocked it out. Check out the RV Factory/Shop topic for more.

Once that was complete, I got to dimpling my skins. The DRDT-2 make single pilot dimpling a breeze. I did have to take a couple of breaks in between each half to let the arm recover from the plunger lever. All in all, this thing makes great, consistent dimples.

I did read a bunch on preload on the DRDT-2. I simply set the plunger to 0″ clearance on the dies, then made one more turn on the plunger and then tested on some scrap .032″ Vans pleasantly supplies in the kits. Simply perfect dimples.

Once all the dimples were complete, I scuffed the inside of the skins and made sure all the parts were ready for primer. I hope to prime tomorrow and then let it sit over the weekend while we do some family/CAP business.

One of the needed tools to complete an aluminum airplane that uses flush rivets is a “C-Frame” dimpler. There are several types. Once uses a mallet to smack the dimple dies together and then there is the DRDT-2. Instead of using a mallet, it uses a lever and a fulcrum to produce the pressure between the dies.

Since I have smashed enough fingers in my time with a hammer, I was VERY leery in taking a mallet to hit anything around my new airplane parts. Particularly around the skins that are typically dimpled in a “C-Frame.” There are plenty of guys that have good success, but I did not want to take the chance. Another problem with the mallet type is that if you slip while getting your swing ready, and move the  skins when you hit the plunger head, you can create the proverbial “Figure 8” hole in your skin. Basically, the force is great enough that you drill another hole with the dies right next to the hole you are actually trying to dimple. The DRDT-2 helps eliminate this as you can precisely place the pilot of the male dimple die in the hole and then just pull the lever down to actuate the plunger.

Before I got into any real heavy dimpling, I needed to mount it to something. When I bought the tool many months ago in preparation to build, I constructed a platform/table per the instructions provided by the tool manufacturer. However, the tool itself was never mounted to a bench. Some builders do, some don’t. Having three young children around, I don’t take chances with expensive and heavy tools that can be anchored. It is better to protect the kids and the tools.

When I constructed my benches, I modified the EAA1000 tables to essentially make a single 4’X6′ table. This left a 2’x4′ piece of ply left over. I figured I would simply make a smaller bench to hold my band saw and drill press. That idea lasted a short time when I wanted to place my bench vise and 12″ disk sander on the same bench. Needless to say, real estate was dwindling fast. So I built another 4’X4′ bench to make a 4 tool bench and mount all those tools to it. That left me with this 2’x4′ bench again. In shuffling around stuff when the Tail and Wing crates arrived, I set the DRDT-2 on this extra bench, and it became clear, the DRDT-2 has a home.

So I bolted it down today to the bench with some 5/16″ x 1.5″ bolts and then used some left over carpet from the house that was in storage and covered the support platform. Took me about 20 minutes and shortly after I got busy dimpling the Horizontal Stabilizer skins. The little bench that wasn’t enough earlier was perfect now. Worked like a charm.

So if you are trying to decide between a standard “C-Frame” mallet type dimple frame and a DRDT-2, I cannot comment beyond what I have read on the standard, but I can tell you, the DRDT-2 is great and works as designed. I hope to get my lovely wife on it for the Vertical Stabilizer skins. I am not sure I would say the same if she was using a mallet. 😉

Was able to get all the skeleton dimpled tonight. The last holes at the nose of rib HS406 needed my pop rivet dimple dies. Sure glad I had a set.  I then dressed all the edges, and then double checked all the scuffing.

I need to get my DRDT-2 table rigged up so I can dimple the skins to match the sub structure. Hopefully sometime this week I will get to it. Once that is complete I will prime all the parts and then start final assembly of the HS sub assembly.

The Tricky Drilling

After a good restful sleep, it was time to get some real work done. I mentioned in the previous post, several mistakes have been made in the assembly of the HS by other builders. I did not want to make the same ones and was now willing to take a swing at it.

The first area of concern is the flange of the forward HS404 Rib to the HS702 spar connection. Despite my best efforts, I made a similar mistake that others have. The problem stems from needing to drill from the back side of the HS405 rib, through the HS702 spar into, the HS404 flange. You are essentially doing this blind. This left me with the 2 holes in the flange a little closer to the 2x Diameter to the center of the #30 hole distance recommended, but within the MilSpec (MS) required edge distance. The other contributing factor is that when the HS404 rib is installed into the skin opening for it, it causes the rib to concave some and moves the flange inward. The flange could be scabbed and replaced, but I have chosen to build on as it is not a structural connection and it is within the MilSpec.

The second problem with the backside drilling is that some have busted the edge distance of the stiffeners when drilling though the spar and the stiffeners. I was very concerned about this connection as it IS structural for the empennage. I was VERY careful here and pleased to report that on the left side, I was well within the edge distance when drilling these holes. Whew!!!

Once the HS404 and HS405 ribs are match drilled to the skin, you then completely match drill ALL the holes in the skin to the sub structure. My hand got sore undoing and redoing all those clecos. Remember, they are on both sides of the HS in this picture. I love how precise all the punched holes are in all the parts Vans supplies. Made lining up everything a real dream. In older kits, you had to lay out the rivet holes in the skin and then drill them all then match drill them to the sub structure. I am glad I don’t.

The above shot is of the Left HS complete and ready to be disassembled. Wait…I jut got it all together and looking cool. What do you mean I have to take apart. Welcome to building a plane. I took out all those clecos, and set the parts aside. Then next step is to dimple all the holes and the corresponding holes in the sub structure to accept the flush AD3 rivets. Then I will prime and begin to reassemble for the final time. The real riveting will begin soon enough.

With the left side complete, it is time to repeat all the steps just completed for the right side. With the hard stuff figured out, and experience now fresh…this will go like a breeze right? WRONG!

Remember back in the HS405′s Prepped and Drilled post when I noted that forward flanges were not located symmetrically? Well it came back to bite me. I was able to successfully drill the HS404 to HS702 flange connection correct this time, but when it came to the stiffeners….well, I thought, heck it worked on the other side just right…it will work here fine too. Long story short, when drilling through the HS405 through HS702 through HS710 hole, I looked and was horrified to see that the hole looked to have busted the 2x Diameter edge distance. After a few thumps to my head in frustration, I measured the hole. I am at 0.250″ from the center of the hole to the edge! That 1/4″ looks way smaller when you are scared. Crisis averted.

New Builders beware of the HS405 webs….they are not created equal and must be the cause of this common mistake. The forward flange IS NOT CENTERED on the rib. You will get different height holes on the HS710 and HS714’s no matter what you do!

Right HS Completely Matched Drilled and Ready to be Disassembled

Once I recovered from what I thought would be a costly mistake, I pressed on and match drilled the right HS Skin to the skeleton. If I had enough clecos, I could have made a full HS looking structure temporarily. Alas…in time, I will do it permanently.

The last thing to get accomplished today was to clean all the skeleton parts, lightly scuff them, and then mark the part numbers and locations on them. I will dimple the parts sometime this week and then clean once more and then prime them. Additionally, I will use my DRDT-2 to dimple the skins and then prime the inside of them. Then the fun of riveting will begin. THAT was a good day of real progress.

Left Skin Fit to Sub Structure

Now that the sub structure/skeleton is completely prepped/drilled, it is time to cleco on the skins and match drill them together. Here is the start of the left HS skin. Once this is on, you have to complete the drilling and fluting of the inboard ribs that surround the fore spar. Then you match drill them to the skin, the spar, and the stiffeners. Here is where I have seen several make some mistakes that are costly.

Another View of the Skin Attached and the Inboard Ribs Slipped In

It is starting to look like I am building a plane. I called it good for the night. It was late and I needed to take a break and snuggle with my lovely wife.

Here is a shot of the HS ribs marked, separated into Left and Right sets, and half are cleaned and deburred. I fluted using my fluting pliers and they all came out straight. A little more cleaning and they will be ready for assembly into the skins for match drilling and beyond. I am almost to the point where it will look like I am starting to build a plane.

One Side Drilled, One to Go

After the HS404’s are notched, the next step is to mark and drill the forward flange of the HS405 ribs. These are located between the forward spar and the rear spar of the HS. The tricky part is making sure that the holes you mark and drill here provide adequate edge distance to not only the flange you are drilling, but the flange of the HS404 tab that was left after notching it, and the stiffeners on the forward spar. I followed the plans to the “T” and still measured 15 times.

I noticed that while the ribs are symmetrical top to bottom, the bends for the skin flanges are not. This means the forward tab is higher than the other if you place these back to back. So, as you can see, the marks on the tabs above are not exactly a mirror of each other. They are offset by the differential in the bends for the flanges being different.

That being said, I was able to mark and drill so that it met all the required distances and compensate for the offset of the tab just fine. This will ring true when they are matched drilled to the spar and stiffeners and the leading edge ribs (HS404’s).

I also learned the value of a good center punch. Makes locating accurate holes a breeze.

HS404’s marked per plans

One of the next steps after getting the Fore HS Spar prepped is notching the inboard leading edge ribs for the HS notched to go around the stiffeners prepped in earlier steps.

Here you can see the full size detail on the plans and the ribs with the areas that need removing marked in red. I first drilled the corners with a #30 bit and then rough cut the edges close to the limits with my band saw. Then I cleaned up the edges of the cut with a fine file until they were blended with the holes in the corners.

Here is the result:

HS404’s after Notched Per Plans

They are spot on with the plans and ready to be drilled to the spar. The trick is…TAKE YOUR TIME and file as little as needed. I am learning patience in these early build steps. I think that will be the more valuable lesson as the build progresses.

Here are the two spars of the Horizontal Stabilizer together on the bench. Almost time to get the ribs started and get these two assemblies joined.

Fore Spar Stiffeners Marked for Trimming

Here are the fore horizontal stabilizer stiffeners marked and ready for trimming. I learned that the last holes on the ends are right at the required edge distance. DO NOT take any material other than the milling marks off the ends when radiusing. If you do, you may not make your edge distance specs.

Trimmed and Polished and Ready to be Bent

I completed the trims and then had to make the 6° bends to the tails for the fore spars to make the tapered shape.

The 6° "Bends" Completed

I also completed the bend relief holes in the fore spars and the corresponding 6° bends in them to match the stiffeners. Next is the dimpling of the spars and the countersinking of the stiffeners for the four inner rivet holes.

The hose reel with the 50′ of rubber air hose had a mounting plate that did not exactly work on a stud wall. I thought through all the solutions and ultimately came up with the above.

One of my partners on my Spam Can has a machinist father-in-law with a great set of machinists tools. He had some 1.5″ tubular steel scraps laying around so he cut 2 lengths 18″ long and then drilled the ends with 1/4″ holes to accept 4″ lag screws at 16″ on center for the studs.

For the reel mounting plate, we tapped the 3/16″ thick walls for to accept the requisite 1/2″ bolts the reel needed. I then prepped, primed, and sprayed them to match the reel brackets. Turned out great.

Now I have a hose that can reach any area of the shop and then some.