Comet Sailplane Project
Today I started working on interfacing the
wing saddle's 3/16" balsa platform with the top of the pylon structure. The
pylon's 1/16" side planking first had to be trimmed to match the pylon's
center frame contour as shown below. Two 1/16" holes were drilled in the top
of center frame for alignment purposes as shown below.
After the three pieces of wing platform were
glued together and sanded, a line was drawn down the center. Two fore and
aft 1/16" holes were drilled to match the those in the top of center frame
and 1/16" dowels were then inserted to align the wing platform with the
pylon structure as shown below.
Since the wing platform has to make good contact
with the 1/4" center frame as well as the 1/16" planking on either side of
the pylon, a second alignment check must be made to insure that the
wing platform on top of the pylon structure will be parallel to the stab
platform before gluing the two together.
To accomplish this, two holes were drilled in a
length of 1/2" aluminum angle, which was bolted to the forward stab
platform's plywood plate with 4-40 nylon bolts and steel nuts as shown
below. Using two construction steel square blocks, the aluminum angle was
strapped to the steel blocks with rubber bands as also shown below.
Then an inclinometer was used to check the level
of the stab platform as shown below.
In this close up, the inclinometer reads
essentially zero degrees as shown below.
The inclinometer was then placed on the wing
platform to check its reading and after several iterations of set up,
trimming and sanding, and set up, etc., the inclinometer read essentially
zero degrees with the wing platform sitting on top of the pylon structure as
At this point it was time to glue the wing
platform to the pylon structure. Aliphatic glue was spread liberally down
the center of pylon's 1/4" frame. The wing platform was place on top of the
pylon structure and the two alignment dowels were inserted. Here is where
the procedure gets kind of tricky. CA was used to spot tack the wing
platform to the side planking in the center. A very quick check was made to
be sure the platform was not tilted. CA was then used to spot tack the wing
platform to the side planking at the front and in the back. Again check was
made to be sure the platform had not tilted
(this looked like a Chinese fire
drill). Once the wing
platform was tacked to the side planking in a number of places, I checked
the alignment one last time. Now I like inclinometers as well as the next
guy, but there is nothing like a good old fashioned visual check as shown
Finally measurements were made at the outside
edges of the work table surface up to aluminum angle on the wing platform.
These measurements were essentially equal within the limits that I could
measure. Once I was satisfied with the wing platform's alignment, CA was
applied to the entire length of the side planking on both sides. Well guys,
that is it for today.....................Tandy