Month: January 2015
The wing tips are attached with screws into the plywood sheeting on the nose and between rib #10 and tip. The plywood is not really thick enough to hold screws, putting some blocks under the plywood seems necessary. Once I glue the plywood on the wing nose it will be impossible to add these blocks so I better do it now.
I grabbed some 1/4″ x 3/4″ RS-5 piece of scrap wood and cut four 3/4″ long squares. I put each on the side of the nose rib and tracef the rib contour onto them. Using the sander and some channel lock pliers I sanded this contour into the block.
Now each piece follows the contour of the rib.
Before gluing these on I weighed them, a whopping 0.144oz. I think I can live with this weight gain.
I used a small file to remove the varnish where these blocks are placed then glued them with epoxy.
Once the glue was dry I varnished the blocks except for the side that will be glued to the nose plywood.
Using a straight edge I ensured the blocks were not higher than the ribs and filled as necessary.
Getting everything lined up properly took more time than expected on this step.
Those RS-1 that were glued to the nose ribs were made too long so I could use rubber bands to hold the nose ribs in place while I lineup everything.
I used the aircraft nails, slightly protruding out the back of the RS-1 to keep the rib from sliding around.
Next I cut a scrap of wood to help line up the ribs properly.
The wide part was placed against the main rib, the skinny part should be against the RS-1 on the nose rib.
I used some masonry string so I could locate the center of the RS-4 stringer at each rib. The small pin under the string was placed at the root and tip so the string is slightly raised from the stringer.
I moved the rib up or down until the string was in the center. The small pin and PVC clamp held the stringer to the proper depth.
The stringer depth was adjusted at each rib until the proper gap between stringer and string was obtained.
Once everything was lined up the nails were driven in further to create an index point between rib and spar. Then each rib was removed and glued in place ensuring to line up the nails and nail holes created previously.
The stringer was then glued into the ribs and depth adjusted to the string as noted above.
I was unable to get a good picture that shows how straight the stringer is but I think it’s near perfect.
Once this is dry I will cut off the excess RS-1 on each rib and round off the stringer using a small plane. Then varnish will be applied to all non glue areas to prepare for installation of the plywood wrap.
The nose ribs need to be prepared before they are glued onto the front spar.
Ribs 2,3,5,6,8, & 9 just need 1/4″ sticks glued to the nose ribs.
The #4 & #7 ribs are made the same except they also need a 1/4″ doubler rib added. Had to cut 1/4″ of the back of a 1/4″ nose rib for proper fit.
The rib doubler at the root needed the top modified to make room for the gusset and carry through bracket.
The root and tip doublers were glued to the outer plywood skin. The other ribs were allowed to dry and will be glued on in the next operation.
Now I just need to make five more to have enough for both wings.
Now that the aileron spar glue is dry its time to install the aileron nose ribs. On ribs #4 and #7 the nose rib is made from two pieces of plywood.
The two ribs were glued together.
Then installed and held in place with clamps. These ribs are wider to provide enough glue area for two pieces of plywood that will be joined here.
I held rib #5A in place using a clamp.
The rest of the ribs were simply stapled in place.
A friend of mine had offered to cut the nose ribs for me on his CNC router. Instead I opted to do it myself because I want to build this airplane not have some computer do it for me.
I copied the template from the plans and cut out the shape on a piece of scrap wood. Then mounted it into a piece of plywood.
There are six screws that hold the template in place.
They are poking out the template just enough to help hold the workpiece in place.
On the template I drilled two small holes in the corner of the stringer cut out. As each rib is cut out I also drilled these holes so I can easily locate the cutout on each rib.
I used clamps to hold the 1/4″ plywood in place and staples on the 1/8″. Each nose rib was cut out using a flush cut router bit.
Here is what a single rib looks like after being routed and drilled using the template.
After all of the ribs were cut out I used the band saw to cut out the notch for the stringer.
Each rib is nearly identical to the others, when stacked side by side they look like a solid block of wood.
At this point I am deviating from the manual. The next step in the manual says to glue the top plywood end caps between root & #1 and tip & #10 ribs. The problem here is that the trailing edge of the wing is not yet glued on and it goes under the end cap. I will not glue the plywood caps until after the aileron is separated from the wing.
To complete the aileron spar I need to flip the wing over with the bottom facing up so the bottom caps and diagonals can be installed.
This is just like the top so I will not go into details here on installing the caps and diagonals. Once all of the components were in place the wing was flipped back over and placed on the flat workbench to dry. The only deviation from flat is I had to use some scrap plywood pieces to raise the trailing edge to make room for the trailing edge gussets.
As you can see I used tape to hold the tiny RS-1 between the diagonals in place. Epoxy does not stick to scotch tape so no worries about taking it off.
The aileron is really taking shape now.
Once the aileron spar webbing was dry I started installing the RS-3 upper spar caps and RS-1 upper diagonals.
It took quite a bit of staples to hold the spar caps in place.
To make life easier I ran the RS-3 spar caps through the router to add a slight bevel so they match the angle of the ribs. While I had the router setup I also ran enough material through for the left wing. The angle is different for the top and bottom spar caps so I made a bundle of each.
This task was difficult only because my workbench is against the wall and tall. A consequence of limited room and designing the bench so it will fold down against the wall. If possible a bench you can walk around all sides would be much preferred, and a large workshop would be excellent.
The aileron spar webbing was rather simple to cut out and glue in place.
One cut to size I slid them into position and used clamps to hold them in place while the glue dries.
At rib five where the two pieces meet it was a little difficult to position the clamps.
With the aileron spar webbing in place I glued the root and tip ribs in place. Sorry I forgot to get a picture on this.