Thursday, January 15, 2009

Controls and Wing Center Section

Build hours: 769

The control system, seat back, seat brace, center spar installation and spar braces have been completed for UCA and UCB.
These are the rudder pedals purchased from Hummel as part of the controls kit. The aluminum welding made our decision to purchase. The lightening holes in the rudder bracket is a recommendation from Hummel that is not on the plans (4 oz). The wimpy looking brace makes for a very solid arrangement.
Plan note:
The lower tab on the brace is too long and flexes to much to be effective per the plans. One builder put a rivet in the tab behind the bolt. We remade the bracket and shortened the tab.
Nylon washers, 1.25" in diameter , .125" thick were placed on each side of the rudder bar for a good fit and smooth rotation.



This is a closeup of the front of the middle rudder pushrod link.


The next link in the rudder pushrod was bowed against the fuselage for maximum arm/elbow clearance.


This picture shows the middle to rear rudder pushrod link attachment. Four threads were left showing on the rod ends for adjustment.

Also show is the placement of the seatback support. The support was put under the rails so that the canopy fit would not be interfered with. Some felt or nylon needs to be added where the seatback rest against the support.


The control stick was curved to better align with the hand. Some trimming of the pre-welded assembly was required to get the stick and horn to center appropriately. Also, 2 assemblies were purchased, one was welded per the plans, one was welded per the welder - someone always knows better than the designer.





Plan note:
The first elevator pushrod link requires an unusual bend to miss your leg and enter the "C" bulkhead correctly.



We made several trial pieces, bent a disaster, walked away, came back and ended up with "perfection":) (And we did it correctly twice!)



The rear bulkhead openings and horns were made a long time ago... Its great when the plan comes together!


The rudder and elevator shouldn't have to be removed so the safety cotter pins were installed, and all horizontal stab bolts were tightened and indexed with a red paint mark.





The inserts for all of the control rods were turned , bored and tapped on the lathe. Only 16 more to do for the aileron pushrods.






The seat was bolted to 2 pieces of angle attached to the bottom rails.



This is the "C1" buckhead. Notice the misaligned centering marks. The error was caught after the picture but before we screwed up :)









Wednesday, November 26, 2008

Ribs and Spars

Build hours: 697
Progress has been made since the last update in August. We decided to build our ribs for the experience, weight savings and to use up all of the accumulated cutoffs instead of buying 2 additional 4' x 12' sheets. So far, the rights side ribs and spars are completed and the left side rib parts are made.
This is the particle board jig to hold the rib parts in place during assembly. The top and bottom caps were bent in the brake and then shrunk to the rib pattern. An endless number of braces were folded (enough for 2 sets of ribs).
Alignment dowels were inserted into the jig to allow the pattern pieces to be moved to the opposite side of the build board to make left or right ribs.




A form was made to bend the nose pieces over and a particle board flanging die made to make the lightening hole flange. Shrinking of the flanges manually and with the shrinker was required.



Finished rib assemblies.

We used 3/32" solid rivets to assemble the ribs. After you get the rivet driving going, its as fast as pop rivets and gives better edge distances.










These are the 4" or 4 1/2" flanging dies for the spar lightening holes. The flanges stiffen the web considerably even though all of those holes only remove 3.7 ounces from each spar.






A 14' jig was made that would hold the spar center section and one outer spar at the correct angle. The spar fittings were prepared and clamped. The jig was set at the correct height for the drill press. All spar fitting holes were drilled undersized and reamed to .002 or .001 under as required.





Additional rounding and cleanup on the spar fittings was completed. All spars are done.

Saturday, August 16, 2008

Spar braces

Build hours: 577

The spar has been positioned and attached temporarily to the bottom angle. The outer spars have to be made and matched to the center spar before the center spar can be fastened permanently. The spar braces were made and ready to rivet. The edges of the spar braces were rolled over to give a more finished look and provide additional stiffness in the process.

The spar brace edge required notching to set on the spar caps.


This shows the spar brace bend angles required to match the fuselage and the bend on the outer edge. The blank had additional width for bending in the brake. After bending, the extra material was cut back.

The wooden brake works well for aluminum up to .025 and even short pieces of .040 but it was not up to the task of bending .062 2024T3 across the grain. A 17" brake made from leftover 1/8" steel angle was cobbled together. The platten has a 3/16" radius which is required when bending .062 2024 in the T3 condition (3X thickness).