Archive for May, 2011

Weekend Update

May 30, 2011

Nothing better than a three day weekend with good weather! In addition to lots of outside time with the fam, I got to dig into the forward fuse some more. Friday night I went through a the forward fuse progress and made a laundry list of to-dos including a drilling sequence for some of the critical drilling on the firewall angles. I did not want to screw those parts up and the instructions in the manual at this point are, shall we say, not explicit. They tell you “what” to do but leave the “how” up to the builder.

First I tackled the connection of the 719 stiffeners to the firewall. I had fabricated the 719B bracket a while ago but waited to drill the holes here until I looked at how others had done it. I ended up using Mike Bullocks method of a 12″ drill bit to drill the two holes in the stiffener and then a angle drill for the hole in the firewall flange. After some careful double checking of measurements, everything came out perfect.

Here’s a shot at the two holes I used a 12″ bit from above (below) get to. Some folks have removed the stiffener and drilled on the bench but I was worried about keeping everything aligned.

Next up was to finish the gussets at the intersection of the lower/auxilery longerons, the firewall mounting bracket and the vertical firewall flange. This must be the most complex intersection yet on the aircraft as three axes converge at the bottom of each side of the firewall. With the gussets I had two rows of rivet holes remaining to drill. I also has already cut the part out according to the plans. Saturday I spent the afternoon with my micrometer and files tweaking the edges until each gusset fit snuggly in place I felt good about all the edge distances.

Here’s a detail of the other gusset. The notch in the gusset is what allows it to fit inside the steel engine mount bracket but ouside the vertical firewall flange. However you can’t let the notch get too big in order to keep your edge distances tolerable. Confused yet? Me too. I took my time and drilled the vertical flange with the skin peeled back. Then used the skin to match drill through the bracket at the horizontal row above. It all turned out good and I’m very happy to move on.

On Sunday I prepped and installed the 902 bulkhead and the 7101 Gear Attach Web. There was a small gap where these parts meet up (see the four copper clecos in the pic above). I added a .020 shim between the parts for a better fit. The foward fuse with the bottom skin cleco’d back on is pretty stiff now. I am going to skip ahead and fit the floor stiffeners next before tackling the fuel tank attach and the rudder pedal install.

 

Bullet Misses

May 25, 2011

As Planecation 2011 drew to a close, I started to read ahead on some builder sites about the sequence of some upcoming drilling. When I was checking out Mike Bullocks excellent build log, I found his entry on edge distance issues for the bolt holes in the lower engine mount that I just drilled. His measurements seemed to be the same as mine but when he contacted Van’s they wanted him to have a little more. So after a bit of freaking out I got out to the garage, took the lower longeron off and got a pic of the holes in question. I then sent it to Van’s for their assessment of the situation.

Meanwhile I tried to hypothesize what the best or easiest solution might be. I could possibly weld the holes shut and redrill but that might warp the part or make the face of the bracket bumpy and unusable. The best alternative I could come up with was to just bite the bullet and drill out the 32 rivets that attach the lower engine mount brackets to the firewall. It wouldn’t be easy but seemed to be the path of least resistance

I am happy to report that I heard back on Wednesday that it edge distance looked ok and to build on. Whew! I am super relieved. However, I’ve also sent this pic to my tech counselor who’s QC engineer over at Boeing just for thoroughness. This is a very important intersection so I want to feel very assured that this joint will perform within Van’s engineering specs. For now the bullet has been dodged.

Planecation 2011: Day Five

May 20, 2011

I concentrated on the F-717 lower longerons today. In the morning, I trial fit them until getting the twist and the length just right.

In the afternoon, I decided to go ahead and drill the holes for the AN3 bolts that attach the lower longerons to the lower firewall mounts. These are 3/16″ holes so there isn’t much room for error here. First I drilled a #40 pilot hole and then opened it up in steps up to a #13 drill. I used a squared piece of wood to make straight holes. Finally, I finished them to final size with a 3/16″ reamer for super clean holes. They turned out really nice. I’m super happy to get done with this step.

Planecation 2011: Day Four

May 19, 2011

With the firewall attached I could move on to fitting the additional longerons and stiffeners that make up the forward fuselage. Each of these six pieces are made of angle stock and need to be custom cut, twisted and fit into position. In the photo above you can see the top longeron in the bottom of the frame (remember the fuse is upside down right now). In the middle is the forward stiffener and up top is the auxiliary longeron. At the very top (not pictured) will be the lower longeron which is a relatively beefy piece of angle.

First up were the auxiliary longerons. They were pretty straight forward to drill into position using clamps and the skin holes for guides. Again the connection to firewall weldement is important so I took my time here.

Next were the forward stiffeners. These are a bit more challenging because you basically tape them into place to start drilling because there no way to clamp them in place. I got the right one done quickly and felt pretty pleased with myself. Then I got in a bit of a hurry and drilled the first hole in the left stiffener before realizing I had slightly misaligned the fore/aft positioning when I retaped it . Technically the hole has enough edge distance but this stiffener “joggles” over the another piece on the other side and I couldn’t salvage that alignment.

It doesn’t look like much in the photo but the 1/16″ I was off here messed up the seating of this piece on top of the 704 sidewall on the other side. It’s a $6.80 part so not a big deal to order another one. There’s plenty more I can do in the meantime.

This evening I started to trim and bend the F-684 gusset that provides more strength to the lower firewall area. It’s got quite a number of critical dimensions and bends in order to fit correctly. I only got the left one roughed out before running out of gas.

Planecation 2011: Day Three

May 18, 2011

Yesterday I got to clamp the firewall on for the first time. Today’s mission was to drill it to the main structure; time to get out the ruler! I spent most of the day aligning the firewall well before drilling it. A straight firewall minimizes adjustments to the engine mount later. The instructions say to measure 5/8″ from the front face of the firewall to the end of the side skin. This is because the stainless steel flange of the firewall has minor variations in its dimension so you can’t just align the flange with the skin.

I must have put on and taken off the firewall about two dozen times as I filed the longerons and remeasured over and over. After I got it as close as I thought I could, I drilled a hole on either side of the 772 bottom skin to the lower firewall brace. This set the distance for the bottom dimension while the longerons determine the top dimension. Then I drilled all the holes in the side skins to the firewall.

With that completed I started work on the 1/8″ holes that attached the top firewall weldments to longerons. Vans has you insert rivets into the holes you’ve already drilled through the skin and longeron here to keep everything aligned before drilling into the steel.

This is as far as I got today. Progress is a little slower than I would like but these attachments are critical to get right so I don’t mind taking the extra time.

Planecation 2011: Day Two

May 17, 2011

I dropped the kids off at daycare, grabbed a Starbucks, and got back to the airplane factory around 10am. First up, I finished the leftover longeron drilling. Next it was time to trim back the front of the longerons so they are exactly 3/4″ shorter than the 770 side skins. So far so good.

I had been bothered before that I didn’t get a good crisp bend when I made the downward bend in the longerons. The side skins make a revatively sharp angle where the downslope starts at the forward fuselage. The result is about a 3/32″ gap between the vertex of the longeron and the edge of the 770 skin.

My solve was an idea I came across in another builder’s log (I forget which one). I took one of my bucking bars and wrapped it in tape. Then I clamped it to the longeron and to the sawhorse. Pulling up on the longeron and giving it a whack with the hammer I tried to get a more exact bend on the longeron. I was able to reduce the gap by about half in the end.

After that I clamped the rest of the skin to the longeron and drilled the remaining holes.

Next up I had to fabricate some straps that marry the tops of the 704 bulkhead to the longerons.

And here they are in place on the fuselage. It was getting later in the day so I just had time to get the firewall temped into position.

There’s some critical measurements to make sure the firewall is perpendicular to the trust line of the aircraft. I will be studying that tonight before proceeding further. I’m also running out of clecos so I will need to scrounge up some more as I start drilling the firewall tomorrow.

Planecation 2011: Day One

May 16, 2011

I have this week off from work. The rest of the family is on their normal schedule, so other than some dog walking, I am planning on making some serious headway in the airplane factory. My goal is to finish all the forward fuselage work by the weekend. First up though I need to finish drilling the longerons from the tail all the way up to the 704 bulkhead. This takes Zen-like patience and concentration as there are hundreds of holes and some tricky intersections here and there. I did manage to double drill a hole in the right flange tab of the 710 bulkhead. I’ll report back on the fix later. Pressing on…

I used some bar clamps in the center section area to snug the longerons up to the edge of the 770 side skin.

This isn’t a very good picture but that bottom row of clecos is what I am drilling today on both sides of the fuselage. I took my time and got about 80% done before shutting it down for the evening. A good start but I am looking forward to tomorrow and getting the firewall hung.┬áTime to rest the sore back and butt.

Progress Report

May 8, 2011

Where to start? This should be more like 3 or 4 posts but I’ve been busy with work and family so I haven’t been updating the blog like I should. So here it goes. After finishing the center section riveting, I drilled the 715 ribs on each side as well as all the floors.

The center section then got flipped back over and reattached to the 706 bulkhead. Attaching the 770 side skins was very challenging. I had a hard time getting the holes to match up. It took three days of searching the forums and builder sites for advice to arrive at the solution. You have to basically raise the rear fuse just behind the 706 bulkhead by a good 8 inches. This spreads the longerons a bit and gets those rear holes in the 770 skin close enough to the aft fuselage holes that you can get some clecoes inserted.

After that it was time to match drill the arm rests. Pretty straight forward.

The next hurdle is bending the bottom rear of the 770 skins to conform to the curve of the aft fuse. My first attempt ended with a small crack at the 90 degree bend because I used the steel from my mini-brake and it has a very sharp edge. Joe at Van’s said I could stop drill it and glue in a metal backing but I opted just to order a new skin for $60.

On the second attempt I used a piece of scrap angle that had a slightly rounded edge. This time the bend turned out better but I still ended up with a tiny little crack again. I will just drill and open up that corner a bit to get rid of the crack and help the edges meet better. On the third try with the left skin, I rounded the edge of the angle even more and the bend turned out perfect. I’m very satisfied to have the 770 skins in place and those corners fitted. Next up will be drilling all the holes in the longerons. Yay!