Before building the wing a few miscellaneous parts need to be cut.
Grooved landing gear blocks were cut from basswood. Grooves were
cut with a table saw. The plywood doublers for the landing gear blocks
were cut from 1/16th ply.
The plans specified 1/16th ply for the wing joiner but this seemed pretty
light so I did mine from 1/8th. Also shown is the firewall and a template
for setting the root wing rib.
Here we have the parts for the wing panels.
Lots of ribs, basswood wing spars, trailing and leading edges
and built up wing tips.
The wing ribs are cut out in pairs. This is a double tapered wing so
each wing rib gets progressively smaller as you go towards the tip.
The leading and trailing edges were notched to accept the wing ribs
with a Dremel Table Saw.
Wing assembly is straightforward. This is just a common everyday
"D" tube wing.
Note the tapered length of wood underneath the trailing edge.
This is to allow the tapered wing panel to be built on a flat surface.
Instructions for making this piece are on the plans and described in
the construction article.
**NOTE** Be sure to use the tapered trailing edge support jig correctly.
The taller 15/16 inch end goes at the root end of the wing. The shorter
1/2 inch end goes toward the tip.
Using a straightedge to be sure not to build a curve or twist
into your wing. Its surprisingly easy to build a warped wing.
A straight wing makes for a straight flying airplane.
Note the various size sanding blocks. I tend to make a lot of sanding
blocks. You will too if you decide to scratch build an Ultra Sport.
Buy lots of sandpaper.
Here we are installing the shear webs. Note that the webs go all the way
to the tip. The shear webs on this plane are done differently from what
Ive seen in the past. The webs are attached to the back of the wing spars.
This creates a "C" shaped structure rather than the more familiar "I" beam.
It seems to work fine and probably the easiest way to do it since if you
notice each web is different due to the tapered wing. So I just glued
oversized pieces between the wing ribs and sanded flush with the spars.
The trailing edge sheeting was attached at this time.
Leading edge and center sheeting is now applied.
Also added cap strips over the wing ribs.
Wetting the leading edge sheeting is helpful so it can conform to the
curve without splitting.
Wing panel is removed from the board and the landing gear blocks are
installed. Dont forget the plywood doublers to reinforce the gear blocks.
I used twice the indicated number of doublers. I used one on each side
of each rib. Instead of just on one side of the rib. Use plenty of epoxy.
Add bottom sheeting piecing around the gear block. Leave off the bottom
center sheeting for now. You need to get in there to install the wing
joiner when joining the wing panels.
I made a mistake here. I should of left some of the bottom sheeting
off until I had installed the wing dowels through the leading edge.
It would of been a lot easier to install. I remembered to do this on
the left wing panel.
Now do it all again to build the left wing panel.
Remember to make ONE right panel and ONE left panel!
The decision was made early on to go with separate aileron servos
mounted out in each wing. This is not shown on the plans. But its
an arrangement I like better than torque rods.
Servo trays were made from basswood scraps left over from the wing
spars and scrap pieces of ply.
I decided to put the trays in the 3rd wing bay. I chose this location
since there would already be sheeting over this area. This way I could
sheet right up to the servo. And the standard length servo leads would
be long enough to reach the radio compartment.
The tray is inset in the bay so the servo top is flush with the sheeting.
Dont forget to cut the holes through the inboard wing ribs to route
the servo leads through. Much easier to do if you remember to do it
before adding the rest of the bottom sheeting...Dont ask.
I used a hole saw made from a length of brass tubing. Cuts nice
clean holes.
Time for the wing tips. These were built up using pieces of 3/8
balsa stock. This is a good place to use an aliphatic resin glue.
Cheap...no nasty fumes and sands well. I used Elmers Yellow
Carpenters glue. I used a lot of it during the construction of this
plane. I used it wherever there were large areas to be glued. Like
laminating stock together to form thicker blocks and gluing in the
fuselage doublers.
Glue the wing tip blocks on. Check the fit with the aileron stock.
The wing tips are worked down to fit the profile of the ailerons.
Start shaping the wing tips. I used a razor saw to cut off the corners
and then used a Master Airscrew razor plane to carve out the initial shape.
Final shaping was done later with a sanding block.
Now that we have two wing panels its time to join them.
Here we have the two wing panels and the already fabricated servo
trays. Note also the plywood wing joiner and the two holes drilled
into it. Those holes are for the wing mount dowels. They run through
the leading edge back into the wing joiner.
Use plenty of epoxy to join the two panels.
Note that the top of the wing lies flat on the table. There is no
dihedral. The top of the wing is flat. In fact you should be able to
lay a straightedge along the top wing spar.
The bottom of the wing tapers upward and this gives the wing all the
dihedral it needs.
Prepare the wing for the plywood wing joiner.
You will need to cut a slot in the root ribs so you can slide the
wing joiner in place.
Another look at the wing joiner.
The plans called for a 1/16th ply joiner but this seemed pretty flimsy
to me so I laminated two pices of 1/16th ply to create a 1/8th inch joiner.
Might be overkill but I build strong not light.
The joiner is now fit into place. Use plenty of good 30 minute
epoxy here. Nothing ruins your day faster than a wing joint failure.
Fiberglass that wing joint.
I probably should have used wider glass tape. But I used what I had.
Its held up fine so far. This is one strong wing.
30 minute epoxy once again. Work the epoxy into the glass cloth.
Then hit it with a heat gun. The epoxy thins right out and flows like
water. The result is a nice smooth joint with the epoxy soaking well
into the wood.
You should disregard the portion of my anatomy sticking out into
this picture.
Here we are gluing in the servo trays.
I thought about making some ply doublers to spread the load out over
the wing ribs but it didnt seem necessary. Once glued between the ribs
it is quite solid.
Notice also that the wing dowels are in place. I made a couple of
rings from 1/16th ply to reinforce the joint between the dowels and
wing joiner.
I made another mistake here. I put all the sheeting on before I added
the wing dowels. It would of been a lot easier without that bottom
sheeting on.
Finish up the bottom sheeting.
Note how the sheeting covers up the servo trays except right where
the servo sits. The top of the servo is flush with the sheeting.
Another boo-boo here. Just how do I fish those servo leads through
the wing with everything sheeted? Some creative use of string and a
small weight helped out here.
Here I have added the plywood reinforcements for the wing mounting
bolts. Holes will be drilled through these later to accomodate 1/4-20
nylon bolts.
This pretty much completes the wing. There will be lots of sanding and
shaping on it later on.
Time to move on to the fuselage.