The wing spar is being made out of wood. Many careful laminations of wood will ensure that the main wing spar does not snap or crack under stress. 1. The spar is laminated together using aircraft grade spruce layers. Note the six degrees of right and left dihedral built into the spar.
2. Hardwood blocks made from white maple are then epoxy glued into place along the spar center line.
3. Aircraft grade 1/8 inch plywood with a 45 degree bias is cut as a shearweb and then glued into place using a 12:1 scarf joint.
4. Urethane varnish is then applied in five separate coats to protect the wood.
One of the retract shaft supports clamped to the aft spar face.
Here we see both sets of retract shaft supports with the upper retract arm in place. Note the rod-end bearing that will attach to the lower retract arm in the following picture.
One of the main gear legs with the lower retract arm attached to the lower portion of the leg and joined to the upper retract arm. One of the down-lock latches can be seen attached to the upper portion of the gear leg.
I have drilled the mounting hole through
the spar and enlarged them to accept the 3/8 in. bushing stock for the
1/4 in. bolts that will attach the brackets seen in the photos above.
The brown colored brackets are for attaching the main gear legs to the
front side of the spar.
The retraction is a simple straight back affair actuated by the
retract shaft that extends to below the cockpit. From there the shaft
will be driven by a series of gears and chain that the pilot will crank
by a handle on the right side of the cockpit.
The upper and lower retract arms act just like a human arm to raise
and lower the gear. The retract shaft attaches to what would be the
"Shoulder" in the human arm and causes the "elbow" or the rod-end
bearing to bend and therefor raise or lower the gear. Large diameter
4130 steel with a 5/8 in. axel bolt for the main wheels will slide onto
the bottom of the leg pictured here allowing toe-in and toe-out to be
set at the proper time.
After the gear and retract is all worked-out I'll start building the
rest of the wing around it. All the wing ribs are done and more rapid
progress should be seen in the future.
Here is a good shot of the rear spar, left tip rib, and bottom wing skin all in one picture. The aileron will fill the space between the tip rib and the trailing edge rib seen in the upper right of photo.
The skin is cut and hanging here from the center line to the outer wheel well bay ribs. Clearance for the gear legs and wheels are progressively cut to prevent too much skin being cut away.
Right side of wing.
Here is a nice straight rear spar ready for riveting. This is the second set of rear spars that I've made. My hangar mate's Bearhawk wings are seen in the background. He's my project overseer who reviews all of my work like making sure that the rear spars are straight!
You can see the center rib, the retract shaft, and the sprocket leading to the right gear leg (painted white). Its support bracket is painted green. Each rib has a strip of wood screwed to it to keep it straight. Even so, the whole set-up wants to sway like a Hawaiian hula dancer until a series of aluminum strips are clamped to the top backside of the ribs to prevent this. Of course, the wood is removed prior to closing the wing.
This is a close-up of the trailing edge skin that the two larger pieces of skin can't cover. Cut-outs at the base of the trailing edge ribs allows for the passage of the aileron torque tube. Again, the protective plastic sheeting will be removed before riveting.
This earlier view of the ribs shows them standing straight like an army of soldiers.
You can see the first of the bracing strips on the back top side of the ribs. Squares, plumb lines, levels, and taught string lines are all needed to ensure a straight level spar with perpendicular ribs without a twist. "You don't want to build a flying corkscrew!!!" is what I've been told.
Here's the left wing in the horizontal position. You can see that the aileron is now attached.
Rear Wing Spar ConnectionRear Wing Spar Connection Wedges