Posts Tagged ‘gusset’


January 10, 2012



The side gussets and rails are installed next. The gusset provides the anchor for the cabin frame as well as a slot for the canopy latch. The holes were straightforward to cut. After drilling (4) 1/4″ inch holes for the radius on each corner, I filed into shape and drilled then into place with the rails and the 705 bulkhead.

Here’s the final position. I’ll need to come back and countersink the rail rivets and the middle rivets of the gusset/longergon/705G interface as the cabin frame will mount directly onto this area.

For now though, on to the forward gusset. This is a deceptively tricky fit so I’ll kinda show my step by step process if anyone might need some reference later.¬†First the front edge needs to be trimmed to fit flush against the firewall. You can’t revmove too much though because you still need to spread 14 size -4 rivets along the long dimension.

I had to shorten the spread on the last two rivets to get everything inside the edge clearance needed after modifying the front edge of the bracket.

Next I bent the short dimension where the gusset snugs up to the firewall so that it would lay flat on the firewall angle. I also increased the bend where the gusset overlays the longeron so there would be good contact between the parts. I used my table-top break and my big bench clamp to do all the subtle bending.

Once the gusset nested nicely, I drilled #40 pilot holes for both dimensions of the gusset.

Then I opened the holes up to #32 and finished them up with a #30 reamer carefully checking the angle of the drill to keep the holes straight.


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.


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.

Firewall Countersinking

April 1, 2008

I finished all the countersinking tonight on all the stiffeners and gussets. The hard wood jig I use to hold the part while using the microstop in the cordless drill is working great. I started to dimple the firewall, but after a few holes trying to holding the part and dimple by myself I thought better of it. I’ll get Annabelle to help out later this week.

Tasks Completed:

  • Finished countersinking stiffeners and gussets
  • Started to dimple firewall

Firewall Drilling

February 23, 2008

Tasks Completed:

  • Fabricated F601E stiffener
  • Started match drilling stiffeners and gussets to firewall