Saturday, December 6, 2008

empennage complete... back to the wings!

13 hours

The empennage is complete!  I spent the morning finishing the left elevator, fitting both elevators to the horizontal stabilizer, and rigging the assembly.  Now it is hanging on the wall ready to fly!

While bending the leading edge of the left elevator I torqued the vise grip into the top skin and had to stop drill a crack... a bit irritating but nothing to be done about it now... later I will do something about it, file it out,  epoxy or glass it in.

Back on the wings, I planned the wiring and power runs through the wing for the pitot and AOA tubes, the pitot heat, autopilot servo, and wingtip conduits.  After reassembling the skeleton I completed riveting both wings.

Completing the elevators brings the empennage full circle as they are fitted and rigged to the horizontal stabilizer, the first part constructed.

finished left elevator...
The left elevator with the additional detail of the trim tab includes a third leading edge opening for the wiring to the servo so you have to bend three sections rather than two.  This should make it easier to get uniform bends for the skin closure, and it does... but the size of the gap at the trim tab opening is much smaller than the access openings for the rod end bearing points.  When I moved my vice grips into the smaller hole grabbing the wooden dowel used to prebend the skin I did not notice that I was putting pressure directly on the skin with the vice grips which caused a small crack.  Very irritating.  I am NOT going to replace this skin so I stop drilled the crack and will figure out what to do with it later.

the offending crack at the servo opening
later, I ended up expanding the opening a bit to include the stop drilled hole 
fitting the elevator to the stabilizer some skin needs to be removed 
I used a nibbler, files, and some emery cloth to finish
balancing the elevator it is clearly overweighed in trail...
I had to add quite a bit of weight to balance the elevator... as you can see in the photo the lead counterbalance weight has been cut down incorrectly... the full weight is needed to counter the additional weight of the trim tab and servo.  I will need to remove the weight and reinstall a full cast one.
As it turns out I set this issue aside and forgot about it until much later during final assembly of the tail when the balance issue came up again.

the empennage is complete... pretty much anyway ;)
moving back to the wings, I drilled holes for wiring access and a conduit run from the wing root to the tip
to get alignment of the conduit holes I drilled them in pairs transferring a pilot hole from a left flange to a right to a left...
wing and ribs ready for rivets
riveting the forward attachment points on the ribs 
typical rib to spar rivets
finished riveting the ribs
wing off of the bench and back in the stand
with the wing structure riveted I pulled the wing conduit
one wing ready to start skinning