Siderails

Build hours: 70

The horizontal stab inboard and outboard doublers were cut from .040 6061. The doublers were drilled with 3/32" pilot holes for rivets and the 1/4" stab bolts. The doublers were then formed on a 3" PVC pipe to conform to the bulkhead F radius.

The first siderail was time consuming because the plywood had to be trimmed multiple times to arrive at the correct radius. (see note) The bending process goes quickly and took every large clamp available. It seems you can never have to many clamps.

Plan note:

The plans indicate a 104" radius for the siderail plywood form. A 52" radius (half of the 104" indicated?) was used to get the desired bend after springback. Well... the plans said the plywood may need to be trimmed:)

The blank angle was loaded and the arc center of the siderail and the form was aligned.

Multiple clamps were used to keep the angle from twisting and raising the form.

Note the amount of springback after the siderail is bent and released.

An for the final results.

Bulkheads complete on UC 2

Build hours: 62

The second set of bulkheads have been hung with bulkhead C taking the most time to align. The pushrods guides were added but the tabs still need to be adjusted. Here are the 2 Ultracruisers in there first formation shot.

More bulkheads on beam

Build hours: 58

Bulkhead C,B and A were added to the beam as described previously and alignment was rechecked on all bulkheads. With the addition of the stringers and siderails, the bulkheads will be ready for skinning - time for another materials order.

The beam for the second fuselage was swapped onto the taller set of sawhorses. The beam center lines and bulkhead positions were marked, bulkhead supports were added and F was attached to the beam end.

Bulkheads on beam

Build hours: 54

Center lines were snapped on the beam with a chalkline and plugs of 2x4 were cut and installed in each end of the beam. Bulkhead "F" was attached to the end of the beam with a 1/4" lag screw and secured from rotation with 2 additional wood screws. The bulkhead positions were measured and marked all the way around the beam and the bulkhead supports were attached checking for square, plumb, perpendicular etc!

The bulkheads were then secured in position with C clamps. Sounds simple but a lot of effort went into the alignment of the bulkheads with double checks on all measurements.

Lastly, an alignment tool was made from some scrap Al tube and PVC for positioning of the pushrod guides for installation. The guides have been drilled and clecoed in place.

Beam

Build hours: 44

The beam was built from 16' #2 yellow pine 1x4s. The leftover 4' will be ripped to make 1x2s for mounting of the bulkheads.

Bulkheads near completion

Build hours: 41

All of the corner tabs are in and the control pushrod guides are cut. Final positioning and installation of the pushrod guides will be done after the bulkheads are on the beam and the hole alignment is confirmed. Vertical center lines and horizontal positioning lines need to added to the bulkheads with a final inspection before going to the beam.
Also, the hand riveter head fits the air riveter which will make the next 3900 rivets a lot easier to pull!

Riveter head mod

Plan Note:

The riveter head required modification per the plans to create a domed head out of a flush head rivet. The plans suggest the tip needs to be annealed to be drilled but the tip on the Harbor Freight Hand Riveter drilled without being annealed. The initial attempt with a 1/4", 135 degree drill bit was too deep and created more of a dome than we deemed desireable. Some of the tip (.015?) was remove and a 5/16" bit was used to shallow out the depression. This change created a flatter rivet head.

Bulkhead E2, F and corners

Build hours: 37
Bulkhead E2 was cut from .025 2024T3. The bulkhead was cut, trimmed and filed as before. A 1 1/2" hole saw was then used to cut the lightening holes. The tabs were bent forward and the lightening holes were flanged rearward with a flanging die made from particle board. The flanging process created a bow in the bulkhead which should come out when installed otherwise the bulkhead will have to be remade.
Bulkhead corner tabs were made for bulkhead E and installed. Both bulkheads had some oilcanning after all the flanging so before installing the tabs, the bulkhead was C clamped back to the original form. One E bulkhead was completely drilled and clecoed before riveting and the oilcanning remained. The other was drilled, clecoed and riveted one corner at a time an exhibited almost no oilcanning. The 040 for bulkhead F was rough cut and the rudder and elevator holes were cut with a 2" hole saw. Scrap one piece of .040 when I pulled out the 2 1/8" hole saw! The .040 was tough to cut even with the 14" Andy Snips, luckily there is not a lot of .040 or thicker components!

Bulkheads B-E

Build hours: 31

Bulkheads B through E and a second set of A-E were completed in the same manner as bulkhead "A". Tabs on curved areas of the bulkheads will not lay flat when bending. This was disconcerting at first but most of the tabs will be at some angle less than 90 degrees to match the skin. Tabs needing to be at 90 degrees or more will need fluting or shrinking. Next is to had the bulkhead corner tabs and control guides before moving to the beam.

Plan Note:

In preparation for cutting out E2 it was noticed that the bulkhead template specifies .016 material but the layout on Sheet 0 shows the bulkhead on the .025 sheet. A quick email response from Hummel indicated the bulkhead could be .016 to .025 - builders choice. We chose .016 2024T3 because of the strength and weight savings.

Bulkhead "A"

Build hours: 17
Up the learning curve we go! It took 3 hours to turn out the first bulkhead. Hopefully the experience will allow the next 13 bulkheads to go quite a bit faster.
The bulkhead "A" template was outlined with a Sharpie Ultra Fine Point onto the .025 6061T6. The template was then rough cut with an air nibbler and then trimmed with tin snips. A metal hole punch was tried to punch a clean hole at the bottom of the bulkhead notches but the punch body obsured the hole outline. In the end, the hole was drilled with a 3/16" bit and deburred just as quickly. The notches were clipped and the entire outer edge of the bulkhead was smoothed with a fine metal file.
The blank was then bolted and clamped between the 2 forms. A dead blow hammer was used to tap the tabs over. After the bulkhead was removed from the form, the tabs were adjusted with pliers. The final step was to admire the completed bulkhead!
The pictures represent the steps taken but are not bulkhead "A" or the same bulkhead.

Bulkhead forms

Build hours: 14

The patterns were outlined onto a piece of 5/8" particle board. A combination of bandsaw and jigsaw was used to cut the line on the particle board. Two forms were made for each bulkhead. The form were aligned with two 1/4" bolts and smoothed on a disc sander. The forms were then labeled and marked as TOP and BOTTOM and which way to bend the tabs to avoid a screwup later when metal was involved! Finally the bending edge was radiused with a coarse file, sanded and checked with a radius gage. A final check was made to verify the bulkheads matched the original plans outline.