And the skinning still continues...

Build hours: 117

This shows both sides of C to D installed, the C bulkhead bracing removed, and the B to C skin in place. Notice the level. Siderail levelness was checked many times to make sure that no twist in the airframe was being introduced.

C to D skin:

The C to D skin is easier to work in 2 halves. On the large skin, a slight adjustment on one edge can make a big difference in alignment on the other edges.

Plan Note:

The C bulkhead edge has to be notched to allow for the change of angle going forward. The plans do not indicate the number, placement or depth of notches. After looking at the factory skin picture, it appeared to be notched at the bulkhead tabs and again in the center of each tab. The notches need to be 1/2" to 7/16" deep. To shallow and the B to C skin will gap, to deep and the notch bottom will not be covered by the B to C skin.

B To C skin:

Three braces across the beam were used so that ratchet straps could be used to pull up the B to C skin. This allowed the skin to be positioned while remaining tight against the bulkheads, making sure the notches were covered. The joint on the C bulkhead does not lay as tight as the other overlaps so far but is acceptable. (There are several areas on the UC that only another builder would be able to appreciate the workmanship and this is one of them!) Wood strips and spring clamps were used to make sure the compound curve that occurs in the skin on the siderail was not getting out of hand which would cause ripples.

Finally, a saddle was made from the B and D bulkhead for fuselage support as the A to B skin pattern is prepared.

The skinning continues...

Build hours: 110

The 3/32" clecoes were changed out for 1/8" clecoes and the tail was placed in a saddle so that skinning could continue. Bulkhead "C" was braced so that the edges would remain aligned during the pattern making and skinning process. The poster board pattern was fitted and trimmed for 1/2 of the C-D skin from the bottom stringer to the top stringer. The pattern was found to align correctly on the opposite half and also on both sides of UCB - we must have done something right! The C-D skin will be installed as 2 seperate pieces to reduce waste and make it easier to install. The additional seam will be covered by the turtle deck.

Pictures to follow...

UCB Skins

Build hours: 105

Skins E-F and D-E along with the E2 bulkhead were completed on UCB. Both skins from UCA were used as templates for UCB.

E2 Installation

Build hours: 97

After the E-D skin had been fitted and the E-F skin had been fitted and trimmed to the F bulkhead, the E-F skin was removed and a line was drawn 7 11/32" in from the F bulkhead edge. The beam was cut behind E and turned over. Bulkhead E2 was predrilled and then each tab was backdrilled after aligning the line in the tab hole. Tabs on alternate sides of the bulkhead were done until about 3/4's of the tabs were done. Then, one side was left open while the remaining tabs were completed to the center of the bulkhead.

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.

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!

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.

Bulkhead templates prepared

Build hours: 4

So it has been a few days since the last post. No, we haven't given up already! The bulkhead templates have been copied, cut and pasted to poster board to create a firm template. It was a real treat to create individual bulkheads out of the plans which have all the bulkhead outlines intertwined on 2 pages. In the hopes to document each step I will attach some pictures.

Also, after debating to buy or build some type of bending brake with shop space at a premium and budget to consider, I took a shot at building one. The 48" brake was built from red oak 1x4s, a piano hinge and a piece of steel angle from Lowes for approx. 40$. The brake bent a 45" piece of 2024-T3 .016 with no problem. The brake appears to be suited for the task.

Coming soon - bulkhead forming...