Jan 11, '03
Installing the root ribs
and
Sheeting the wings

The adventure continues...
The root rib prep went well, and the root ribs are now installed on the wing cores. There wasn't a lot to see, so there are no pics - but here's how it went -

• I waxed the wing tube so it wouldn't be installed *permanently* if any epoxy got in the wrong place (bad mistake to use wax w/ (apparently a little) abrasive polish - the tube diameter is now enough smaller that it's just a little undersize.... gotta think about how to fix that...)

• When prepping to glue on the root ribs, I attached clear packing tape to them as a barrier between the rib and the fuse side.

• Then I cut small holes in the tape for the CA, and tacked both ribs to the fuse.

• Glued up one wing at a time
      - Mixed up about 1/3 ounce 15 min epoxy and added micro balloons to make a semi-stiff mix
      - Coated the root rib w/ the mix
      - Test fitted the wing core then removed it to check for glue coverage
      - Filled any gaps w/ more glue
      - Installed the wing core for real
      - Set the other wing in place just for balance.

• Left the shop for the evening.

• Next morning, side 1 was set - popped it off the plane, and did side 2 the same way.

• Took a stiff mix of 5 min epoxy and balloons and filled all remaining gaps between the core and root rib.

• Sanded everything smooth and flush.

Prepping the wing skins
**A personal note here
    - My shop has never been a really, really clean, swept place. The work surfaces are good enough for most construction jobs, and the table is FLAT - it's a slate from a pool table - but it's not usually REAL tidy.
    BUT.... for jobs involving wings skins and covering ( and some other things) it's essential to GET TE TABLE AND SURROUNDING AREA CLEAN.
    It's a real pain to be on the final sanding on that wing skin (about 15 hours into the set of four for the plane), and turn it over to find a gouge in it from something overlooked on the work surface. [no, didn't' happen on this plane... but it's happened too many times before...
    So -- CLEANLINESS  is essential for this set of operations.
   Here endeth the sermon...

The wing skins had been 'built' some time ago - 1/16x4/36 balsa, at weights of 12-15 g per sheet. I used Pica Glu-it to edge glue them together, then sanded like crazy - the wing is about 1100 sq in, and each skin came out at 33-34 g ready to install. I'm pretty happy about that -- seems decent.

By the way, here's a pic of the sanding setup -(The idea is courtesy of Dave L- and brought to you by the Shameless Plagiarism Department)  CLEAN workbench, box fan (to suck the lighter dust away from the job) and furnace filter for dust control. AND A DUST MASK for the operator to prevent filling the lungs w/ balsa dust!

 Anyway, I got the skins all ready and sanded and dusted and dusted and dusted and ... well, you know..

and continued the final wing core prep.
Another aside here -- My intent (again, triggered by inspiration from Dave) was to do ALL the structural stuff on the wing before sheeting it in order to have the smoothest possible wing. Well, I got it done that way - and it should be fine - but there was a lot of head scratching en route - questions like

• How to sheet the ailerons since they're no longer attached to the wing

•     (answer - semi-taper the aileron leading edges and tack glue them in place till after the sheeting is installed.)

• How/ when to install the aileron horn hard points... then find them after the sheeting's in place.
      (answer - the hard points are visible from the aileron leading edge)

• Once the wing and aileron are sheeted, how to accurately find the aileron -wing joint in order to cut the aileron free.

•     (answer - mark the root end of the wing core shucks for the aileron hinge line, and mark the leading and trailing edge of the shuck for the line containing the root of the aileron. )

• How to install the wood trailing edge on the wing and aileron together.

•     (answer- after tacking the aileron in place it's easy - just do all the work with the wing in the shucks.)

So... with all those questions hanging, and not too many answers yet, the work began.
 

I'd trimmed 3/8" off the trailing edges in order to allow for a more ding-resistant trailing edge. I built up trailing edge with a laminated trailing edge made up of a strip of 1/16" ply sandwiched between layers of 1/32" balsa to the necessary thickness. Edge glued it to the core trailing edge, and then sanded it flush. When the wing is sheeted, solid wood trailing edge w/ a ply center should help to reduce the effects of hangar rash etc.

Weight check -- the wings, ready to sheet less the carbon spars and the actual sheeting, weigh:
    Right: 7.8 oz /  221 g
    Left - 7.5 oz / 214 g
again - I think we're in the 'satisfactory' range here. We'll see.
(hmmm.. let's see... 221 g for the wing + 2x34 g for sheeting... +estimated 35g for laminating resin...+ 65g for servo and linkage... +70g estimated for covering - wing weight might be 459g, or about 16 oz  per wing ready to fly...

This picture shows the beginning of the actual wing skin installation. The first skin and the carbon spar are in place under the core. The trailing edge is in place and has been sanded flush to the core, and the .007 x 1/2" carbon fiber surface spars (top and bottom of the wing) are  in place. I used a 1/2" wide sanding block and a jig to sand a groove in the wing core so the carbon will be flush to the wing skins.

Here's one of the wing skins coated with Smooth 'n' Easy resin, and ready to set in place. Each skin used between 3/4 and 1  fl oz of resin, including setting the carbon spar into each wing surface. The resin amount that'll actually fly with the plane will be a little less than this, since some was wiped off of each skin before installing the sheeting on the core.

This is (duh) the resin used on the wings, and the home made squeegee used to spread it.

And here's the finished lay-up ...some notes -

• The work surface is supported by an all-wood bookcase that's solid and STRONG
  The work surface is supported by a near-solid layer of 2x4 and 2x8 lumber.

• The surface itself is 1" slate - a salvaged pool table top segment.

• Between the two wings is 3/4" MDF

• The total weight (actually two cases of fuel and two boxes full of books) on the wings estimated to be about 150-175 lbs. I was shooting for 200, but ran out of height on the stack.

Now to leave it alone overnight ... and plan the next moves.

01/17/03 -- the wings are out, and they look like they came out okey dokey. I'll show the weight update after getting the wings trimmed and sanded a bit. 

1/23/03 - -the panel weights came out rough trimmed at 331g/ 339g. I'm happy with that -- it includes everything except the covering, aileron hinges, servos and linkages.

01/18/04 - One wing's covered  now -- it averages about 8 hours to do each wing.

Top is 4 colors  --      and the bottom's 2.

Should be easy to tell top from bottom in flight, and that's the prime objective.

Back to
Building a Hybrid Pattern Plane
Root Rib Prep and Mounting
Planes I've Known