Fitting the baggage bulkheads - 4 hours

 I was curious this last while about just how straight the fuse was. When working on the forward fuse and crawling in there doing all the building I've bumped the fuse a number of times. So I set up the laser level on the garage door to shoot a center line. Well...To my surprise and delight it was spot on, so its a piece of mind that I can forge ahead confidently. 

 Now I need to fit the baggage compartment bulkheads. I started in on fluting the curved section of the F-722 bulkheads and then the F- 723 bulkheads. Then I was ready to cleco them in place. 

 

First step I drew a reference line on the tab of the bulkhead that meets with the longeron. I'll need to start figuring out the correct placement of that rivet once I have the bulkhead removed. 

Next I had a good look at the flange/tab that is to mat with the F-623 rib. Lots of builders talk about a gap here and sure enough, I too have a gap but nothing that a 0.063" shim won't take care of.

Before I started to cut a shim, I marked the rivet holes from the bottom skin onto the flange of the bulkhead. Yup, same as many other builders I too have a questionable edge distance on the inboard rib. 

This snafu was in the back of my mind reading other build logs. So it was an easy decision for me to choose making a new flange rather than just use a shim. A new flange with solve both the shim and the edge distance issue.

Finished drilling the outer floor stiffeners - 2.5 hours

 I managed to get the outside two floor stiffeners placed and drilled and not a task that I enjoyed. To start, I double checked the correct center by installing the F-982 coverplate. And sure enough Vans wants the "Centerline" to be drawn based on the dimension of the inside face of the web (3/4"minus thickness of the web) and not based on the full width of the angle (3/4") Insert eye roll here.

Once the 'Centerline' is transcribed on the back of the angle. Now comes the tricky part. Its easy enough to secure the aft end of the stiffener at F-704 bulkhead. I used a block of wood as Mike Bullocks build log

But getting the front end of the angle set is tricky as there is nothing to secure it with. So with the help of lots of tape and my kids holding from below, I managed to get it. Not only is it tricky to get the centerline aligned with the holes in the floor skin, but it is critical to get the whole angle placed forward and aft correctly to ensure proper edge distance on the ends of the stiffener. Drawing edge distance lines on the ends helps with this, but makes placing the angles correctly much more finicky.  

Finished drilling the center two floor stiffners - 1 hour

Not much time to work on the build this week. Fall is coming and the leaves are starting to turn color so I need to get some yard work done. After a long day in the yard, I snuck into the garage and finished the vertical #30 holes in the floor stiffeners. The 90deg drill from my buddy Mike works excellent!

Tinkering with the floor stiffners - 1 hour

Very short build session in the garage tonight. I fiddled with the fit of the 2 centre floor stiffeners. Tried to get that joggle bend sorted so the skin sits nicer.

I then drilled the remaining holes in the stiffener.

Next I need to drill the #30 holes in the vertical portions of the stiffeners, but the area is too tight for my cheap 90deg drill kit. I will see if I can borrow my buddy Mike's 90deg pneumatic drill to finish this portion.

More work on the F-796B angles - 9 hours

Big long day in the garage. I'm motivated to get these F-796B angles done. They are not easy to knock off. Long story short I believe I made about 6 or 7 angles total in the end. And only 2 are needed. That goes to tell you that these are a bit tricky to get perfect.

I'll try my best to explain the pitfalls so you only need to make two.

When cutting the angles initially...Be sure to start trimming the 45deg cuts before you do final trimming and shape the ends to fit the inside radius of the longerons/stiffners. This is due to the fact that the longerons/stiffners have a twist in them and they need to be a tad longer once they sit back inside of the longerons. I cut 2 angle just a tad too short because of this.


No question that edge distance is horrible in this area. And ultimately you will not make proper edge distance on those 3/16" holes...as everyone talks about (and Van's tech support confirms) in this particular case, its ok. I drilled one angle with the F-902 bulkhead in place, but the holes do not end up in the right location as per plans I have smaller edge distances than I would prefer. New parts....Again.

I tried my very best to maximize edge distance wherever I could. I want to follow dimensions on the plans as much as possible. So to drill the first hole, I now removed the F-902 bulkhead. Using the lines drawn on the back of the angle I was able to located the first #30 pilot hole.

Then I was able to align the angle and drill the second #30 pilot hole. Perfect! But when I reinstalled the F-902 bulkhead and then went to install the F-796 angle...The fit is really tight and the web of F-907 interferes with the angle.

A bit of head scratching here. But I figure it is best to remove the portion of the angle that interferes with the web of the bulkhead. I still can maintain decent edge distance around the 3/16" holes. So I went to work with the file to take down some of the interference.

In the end, this is all I needed to do to get a really nice fit.

To complete the #40 holes in the F-796 shims, I simply followed the instructions and used the center line drawn on the shims. I used keeper rivets to help keep it all aligned while fitting and drilling. I find they are more accurate than cleco's


Once the shims were in place....I was then ready to install the Angle and complete the remaining #40 holes.

The final fit is excellent

Working on the F-796 parts - 2 hours

Not a big build day. Very unmotivated today to spend all day in the garage. I did manage to cut the F-796B angles to fit inside the longeron/stiffeners.


I didn't reference Van's dimensions on the plans...I just cut them according to the fit. Also, I did my homework last night on the F-796C&D shims and it appears that everyone seems to have issues with the fit. So I decided to shape them to the curve in the bulkhead rather than cut them down. A little time on the sanding station and they fit well. An important note...its only the top half of the shim that begins to interfere with the bulkhead....so trim the spacers according to the fit, and not the entire length of the shim.
Unfortunately I didn't take a picture of the finished product, but you get the idea.  

Worked on the F-772 bottom skin and F-796C&D spacers - 4 hours

I started the days build session by cleaning up the F-772 bottom skin. I feared that I was scratching the aluminum too much by taking the bottom skin on/off all the time. I broke all of the edges with a file, and then used a 3M wheel to smooth them out.



Next I used the edge forming tool and rolled the edge on the aft potion of the skin.


Next step that I wanted to do was to locate the hole on the upper tabs of the F-902 bulkhead to the longeron. They is virtually no room to work with here so before I did anything I marked minimum edge distance on the longeron.

On the tabs. I installed them temporarily, marked where the tab overhangs the longeron. and then started to mark minimum edge distance on all 4 sides.


I then drilled the #30 hole and confirmed proper edge distance. Next I Installed the bulkheads in the fuse and very carefully marked a pilot hole in the longeron with my 90deg drill set. I have just enough edge distance to work with. My drill set is too bulky to drill these holes, I will just need to finish drilling these when I take the longerons off to countersink them.
 
Next I turned my attention to the F-796C&D spacers. I had cut these out some time ago, but now I need to drill the top 3/32" hole. So I got creative.

Now when fitting the shims to the bulkhead, you will notice that you will need to make some adjustments.

Reading Mike Bullocks RV-7 build log, he notes that he had to trim about 1/16" off the bottom shim, and 1/32" off the top shim.. I'm going to do a bit more research on this.