The Wings – Page 1
I chose to start the project with the wings because of the
limited amount of workspace in my shop. I wanted save the fuse for last so I
didn’t have to store a large component for a long period of time. I thought the
wings would take longer to build than the tail section (maybe, maybe not) so I
would start with them. So, here we go.
After having the plans for the ribs copied at a local print
shop, I began laying out the rib sections on ¾ MDF board that I will use as a
router template for rib construction. (A word of warning here; check the
measurements of the drawings carefully. I made sure that the intersections
where the ribs meet the spars matched the dimensions given for that part of the
spars in height. Also, I made sure that the rib center sections measure 26 ¼
inches in length, the same length as my compression struts C-1 and C-3.)
Cutting the MDF oversized and then using the belt sander to sand to the plan
line worked well for me.
I ordered the mahogany plywood for the ribs as follows:
8 each of 1/8” x 2’
x 4’ M90 Cross Cut
2 each of ¼” x 2’ x
4’ M90 Regular Cut
Ordering this way saved shipping costs as 2’x4’ is the
largest size that can be shipped without extra charges. I also ordered 160’ of
cap strip material cut into 8’ strips and some T88 epoxy.
After ripping the plywood into slightly oversize strips on
the table saw, I used a router to begin forming the rib webs. This method is
very easy and gives great results. The webs are neatly cut and consistent from
one web to the next. Briefly, I sandwiched oversized plywood stock between my
template and an undersized bottom plate. Then I used a laminate trim bit with a
bearing guide on the router to trim off the excess stock.
With all rib webs routed, I then cut the cap strips to
length. My top cap strips measure 48.5” and the bottoms measure 48”. Having
such good luck with the router on the rib webs, and not being able to readily
locate a table saw blade with an exact 1/8” kerf, I chose to route the 1/8”x1/8”
slot in the middle of the cap strip material. In retrospect, it might have been
easier on the table saw. Bowers calls for the front of the cap strips to be
plugged on assembly of the ribs. I chose to leave the cap strips solid in this
area rather than plugging them. Thus, the need for another jig to stop the cap
strips at the right place on the router. Easy enough, I just pulled the router
table away from the wall the right distance and pushed the stock through the
router to hit the wall.
I cut lightening holes in all the nose ribs. I also drilled
the holes in the left wing nose ribs for the pitot tubes. I notched the nose
ribs that will mate with cap strips and notched all nose ribs for the leading
edge stiffener. All notches were cut with the scroll saw - one at a time. Gang
sawing on a band saw would be quicker, if I had one.
I took a different approach to rib construction than what
Bowers calls for in the plans. I built a jig on a flat surface and built the
ribs laying flat on their sides. The jig had straight blocks along the flat
bottom of the rib, a nose rib “socket,” and round cams along the top cap strip.
By doing this, I was able to glue an entire rib up in one setting. I built the
six full sized ribs (7-9R&L). I used spar plugs to ensure that spacing and
fit were good. This method worked extremely well. This method produced
extremely consistent ribs. I had virtually no “sanding adjustments” to make to
the ribs. There are no nails in the ribs. Epoxy tests of every batch (one batch
per rib) were fine.
As
I began to lay out the short rear webs of ribs 3-6R&L, I noticed that the
dimensions given in figure 4-23 did not yield a 90 degree corner on top. After
scratching my head for a while, I decided on the following dimensions:
Top of wing total length aft of spar to aileron bay = 6 ¾”
Bottom of wing total length aft of spar to aileron bay = 6”
Top of web = 6 5/8” (6 ¾” less 1/8” ply on rear)
Bottom of web = 5 7/8” (6” less 1/8” ply on rear)
These webs get notched later for aileron mounting spar
flanges. I decided to notch them prior to rib assembly for convenience. I then completed assembly of the 8 shortened
ribs. Epoxy tests of every batch (one batch per rib) were fine.
Spars were received from Wicks Aircraft. They came cut to net
dimensions (except length) and beveled as per plans. They were not tapered on
the tips. (The grain of these spars was almost perfect, tight and straight.
Couldn’t be happier with spruce for spars.) The plans do not give an overall
length of the spar, per se. Layout of the spar starts at the tip and works to
the butt. However, no detail is given about how far to come inboard of rib #11
for the termination point. There is no right answer here other than making the
wing panels the same, whatever length you use. For the record, my front spars
are 12’ 5 1/16” measured along the bottom edge. Rear spars are 12’ 2 13/16”
measured along the bottom edge. I laid out, in pencil, all rib locations,
mounting holes, butt bevel, and tip taper. I laid the tip taper out on both
sides of the spar so that I could use a belt sander to bevel the top of the
taper after it was cut. I made sure to allow for the 1/8” bevel on each side of
the spar to make sure not to cut the taper too deep and to give me a “sand to”
line for beveling. The bevel is 10 degrees. I also cut the 5/8” off the spar
tip for the tip bow. This would have been easier done prior to cutting the
taper using a miter saw. [One item to note here – the plans give the
measurements for the tip taper at main ribs 1,2&3. However, no measurement
is given for the nose rib 1F location. Use the measurement for the rib itself
and subtract ½ inch (1/4 top, ¼ bottom). The taper pictured below had to be
modified after the fact. The taper between ribs 1 & 2 is a little more
drastic than drawn below.]
I ordered all hardware for the wings per the plans. Corrections
to note: The plans call for 7/32” clevis pins for the turnbuckles. These
are going to be too short. They need to be at least 11/32” long. There is no AN
bolts for the compression ribs that are attached to the wire blocks mentioned
in the plans. They need to be longer than the other bolts. I think AN3-24A’s
will work. Also, Wicks says there is no such critter as an AN-365-1032A nut.
So, I ordered 100 of the AN-365-1032. The plans call for 72” of 4130 tube for
the optional wing wire pad bushings – 84” is the correct length to order.
I had all metal parts made for the wings. All are per plans
with holes predrilled. Ray
Landis made most of these parts.
Home The Wings – Page 4 The Elevators The Landing Gear
General The Wings - Page 5 The Fuselage - Page 1
The Wings - Page 2 The Rudder The Fuselage - Page 2
The Wings - Page 3 The Stabilizers The Fuselage - Page 3