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The steel
used is aircraft grade 4130n chrome moly. All angles cut at 45o which is
easily done on the mitre saw with the metal cutting blade.
The main tube is 1" x .035" x 14", the angled tubes
are .75" x .035" x 3.5" and the rectangular tubes are 1.5" x 1" x .065"
x 1.5". The shuttle tube is .25" x .035" and will be cut to
size when the sticks are made. |
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After the
tubes were cut I used a rat tail file to remove the sharps
from the inner edges and a flat file for the outer.
Where round tubes meet at an angle there is a small gap which
can be filled with a weld but this is the messy way join them.
Instead, I have used a half round file to shape the tube so
that it now looks like it grew there. |
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The
distance between the column hinge points is the same as the distance
between the centers of the 2 seats. The tubes are held
securely
in the jig to avoid deformation when welding. One side is
welded
first then flipped over and placed back in the jig while the second
side is done. |
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The
welding is now done including the addition of the elevator lever
which will connect a tube to the aft spar bellcrank.
The
lever is 0.125" 4130N. |
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After
the first coat of rust inhibitor, I attach the control columns which
have been drilled and had 0.125'' tabs welded to the ends.
The
columns are 0.75" with a wall thickness of 0.058". The
magnets
are holding some WAFs only as spacers to position the 0.25" tube off
the bottom of the main tube. This sets the points for
drilling
holes through the alloy tabs. |
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The
column assembly is supported in brackets with a nylon bearing in the
center. I have used a 1" spade bit to drill a hole in nylon
breadboard. |
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The
brackets are made from 6130-T6 extrusions which have 1 1/4" holes
drilled with a spade bit. The holes are slightly over sized
so
the 1" main tube does not touch them but rests on the nylon bearing. |
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At
the moment the control column is not quite finished but its fit behind
the main spar is perfect. I painted it white to make it a
little
more classy. |
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After
the holes are drilled in the ally hinges, they are propped in place and
a marker is used to define where the main spar holes will be drilled.
The holes in the spar cap and webbing should go through
straight
but they do not need to line up perfectly on the other side, (aka.
WAFs). I have quickly knocked up a drill guide out of a piece
of
hardwood on the drill press. |
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I
drilled a hole in the seat for the control column and then lowered it
onto the spars. It turns out that my seat clearance
calculations
were not correct. The control rod from the column to the aft
spar
bell crank sits too high and contacts the lowest part of the seat.
Rather than cut a valley through the middle of the seat I
have
decided to have a lever welded to the bottom of the control column
which will make the rod run along the fuselage floor. The
piece
of ally is just to test the position before welding. This of
course changes the connections at the rear bell crank as the control
rods now move in the opposite directions. |
