Finished Firewall – 1.5 hrs

Tuesday May 3, 2011

Tonight I decided to buck the last eight rivets on the firewall with my tungsten bucking bar and a flush set. This seemed easier than grinding my back rivet set to match the inside radius of the angle. The first attempt resulted in some superficial scratches on the angle where the bar contacted so I wrapped the bar with electrical tape. The just about eliminated any further scratches. I can easily touch up the surface with some alodine. Here is a photo.

F-601J Angles riveted

Back to the Center Section –

Next the instructions say to make some spacer blocks out of “dense wood or particleboard to hold the halves of the center bulkhead assemblies the correct distance apart. The thickness of these spacers must be 1.438″ (1 7/16″) to match the thickness of the spar.” I began to scrounge around to see what I had in the garage that I could use to make these. I was a little anxious about getting the thickness uniform without a planer or something similar until I found a piece of 1/2 inch masonite that is actually about .475 thick but very uniform. I cut three pieces of this material 3.5 inches by 1.4 inches and clamped them together and measured 1.425 inches with my dial caliper. Only .013 inches too thin and very uniform thickness over the whole area. So I cut two pieces of ordinary writing paper to laminate between the blocks and then applied a thin layer of woodworking resin glue to each block and clamped them together in a vice. With light pressure the thickness of the laminated stack measure about 1.450 inches.  So I applied a little more pressure to squeeze the glue layers down and dialed the thickness in to my target which was 1.440 because that is the thickness of my actual wing spars. Here are the parts of the laminated block before gluing.

Spacer block parts

And here are four such blocks glued together. I used a vice to dial in the thickness then put a C-clamp on each one to secure it while it cures. I’ll let these set overnight and clean them up next time. Then I will drill clearance holes for the bolts.

Spacer blocks glued

Firewall Riveting – 2 hrs

Monday May 2, 2011

All progress is incremental, even when you work to a goal. Tonight I hoped to finish riveting the firewall but I came up eight rivets short. It was good progress though. I used a combination of back riveting and pneumatic squeezer to rivet the firewall components to the bulkhead. Here is how it came out from the aft side. The firewall recess is not supposed to be riveted in until after the brakes are installed, so those rivets were not overlooked. Also notice that I am not installing the Aux fuel pump doubler because I am planning on using a fuel injected engine which has the fuel pump mounted in the cockpit.

Firewall riveting almost complete

On the forward side the surface is completely smooth with all flush rivets.

Firewall forward side

Here are the eight rivets I did not shoot. These are along the inside radius of the F-601J angles and I could not use my back rivet set. I may have to modify the back rivet head or I may buck these with the tungsten bar. I’m going to think about it before diving ahead. It’s late now and I do not want to rush a decision.

F-601J rivets

F-704 and Firewall Work – 6 hrs

Sunday May 1, 2011

This morning I started by riveting the nutplates onto the Center Support Rib parts. These are not the most beautiful Alodined parts in the world but they will suffice especially since they will not be visible in the cockpit.

Cover Support Ribs completed

Then I bolted and riveted these parts to the forward bulkhead of the Center Section.

Cover Support Ribs installed

Then I fabricated the last two parts of the Center Section, the Spacers, from heavy aluminum tubing. I also Alodined these parts.

Center Section Spacers

Here is a shot of the F-704 Web Stiffeners installed on the forward bulkhead.

F-704M Web Stiffener installed

Then I shifted back to the firewall because I wanted to get the aluminum parts Alodined before the weekend was over. I was trying to determine how I was going to soak the longer ribs of the firewall which are about 40 inches long when I had the idea to make a soak tank from a piece of PVC pipe and end caps. It turns out that Vans sent me an 8 foot long J-channel that was missing from my kit in a 2 inch diameter PVC pipe so I cut it down to 42 inches long and made a cylindrical “tank” that I could put the ribs into with Alodine solution for plating. I also used this tank for the Alumiprep etching of the ribs as well. Pour in solution (about half full), then add the part, put on the end cap and slosh it around for 1 minute. I used 30 seconds for the Alodine solution and that gave me a coating that pretty closely matches the main wing spar and Center Section bulkheads. It worked out well and minimized the amount of solution I had to mix up to process the parts.

Alodine plating "tank"

About an hour and a half later I had all the firewall parts cleaned, Alumiprep’d, and Alodined. I even laid the parts out in the sun for a while to dry and “cure” the coating a little. Then I cleco’d the parts back together with the stainless steel bulkhead.

Firewall aluminum parts alodined

I started riveting parts together but there was not enough time today to finish. I’ll keep working on this tomorrow. I’m pretty happy with the way it is looking.

Firewall riveting started

Dimpling the Firewall Parts – 2 hrs

Tuesday Apr 26, 2011

I dimpled and machine countersunk the fuselage parts tonight. The dimpling of the stainless steel bulkhead was easier than expected. The DRDT-2 works as well on this material as aluminum. I took my time to remove each stiffener and reinforcement plate and machine countersink the right holes to the right size and avoid mistakes here.

Firewall dimples and countersinks

Then I cleco’d it all back together. This is ready to clean and prep for assembly. After some research and deliberation I am planning to alodine the aluminum parts before final assembly. I don’t want to prime or paint these parts because of the risk of toxic fumes in the event of an engine compartment fire but I don’t want to leave the parts bare. Aluminum indirect contact with stainless steel produces a pretty high galvanic couple which could lead to corrosion, especially under humid conditions. Alodine provides a protective barrier and makes the aluminum surface much more corrosion resistance than the bare surface. It also provides a surface that I could easily prime and paint later if I change my mind.

Firewall dimpling and countersinking completed

Firewall Parts Deburring and Deglossing – 2 hrs

Monday Apr 25, 2011

No photos today. Time spent deburring and deglossing firewall parts. Boring stuff.

Match Drilled Firewall – 2 hrs

Easter Sunday Apr 24, 2011

The first task today was to make the F-601P spacers and that meant determining what stock to use for these parts. The drawing just says make from .062 thick 2024 Alclad. After looking high and low I found several pieces of .062 thick sheet but eventually I was able to correlate those with other parts based on notes in the bill of materials. Finally I found the material in one of the many bags of small parts (1982-1) already cut to near net size. After a little trimming, smoothing and rounding they were ready to match drill to the firewall.

Match drilling the firewall parts is a bit slower than normal because the bulkhead is stainless steel and you need to lube the drill bit and feed it a bit slower than all aluminum parts. I use Boelube which seems to work pretty well. Here is one of the spacers which extends out from under the steel corner weldment.

F-601 P spacer installed and match drilled

The F-601 E stiffener is made from a 5 foot long piece of angle stock (as best I can determine). It is 8 inches long and chamfered on each end. Here it is match drilled to the firewall.

F-601 E stiffener made and match drilled

Next was to match drill the F-601 J angles. This material is .187 thick and is aligned parallel to one stiffener and 3/32 inch from the lower stiffener. I clamped it in position and match drilled from the far side using the firewall holes as the guide.

F-601 J angles match drilled

Then I match drilled the rest of the holes in the firewall parts. This thing is ready to disassemble, deburr, and start countersinking/dimpling for assembly.

Firewall parts match drilled

Started the Firewall – 2.5 hrs

Saturday Apr 23, 2011

This marks the official start of the fuselage build. I spent at least a half hour locating parts and raw materials for parts called out on drawing 19. I’m still not sure about the right raw stock to use for a couple of parts. I may post a question on the Vans Air Force forum or call Vans on Monday. The first construction step is to make the left and right F-601J angles from 2 x 2.5 x .187 extruded aluminum angle. This is pretty straightforward, cutting to length, cutting chamfers, and smoothing all edges. Here are the finished angles.

F-601J Angles

Then I started laying out parts on the firewall bulkhead per drawing 19. This is not everything, but most of the firewall parts. I’m starting to think a lot about if and how I will paint the interior of the cockpit. This side of the firewall in inboard so if I want to change primer system for the interior this is the time to do it. More research to come.

Firewall parts cleco'd