88.5 Hrs – Ch 14 – Main Spar

Spar Foam In JigCut out the foam pieces for the main spar section after getting together all the foam needed.

Finished cutting the foam pieces to size and contoured the ends of the spar on CS2 and CS4.  Microed the 3 pieces of CS1 together, and called it a night.

Spar Box Inside Ready For GlassingMicroed the spar top, aft, and bottom pieces together and connected per the plans.  Instead of using the pine sticks to hold the spar bottom on perpendicular, I used the Wayne Hicks suggested method of adding the spar front section on, adding nails, and adding weight to keep everything in place.  Seems like it worked ok.

Cut out all the metal parts for the spar, and started filing down the edges where specified in the plans.  Then I microed the end caps on to the spar.

Cut out and shaped the interior bulkheads and marked the spar to show where the bulkheads and aluminum inserts will be placed.

Cut out the rest of the interior bulkheads and marked the rest of the measurements for the hard points.

Vacuumed the foam for the spar and cut out pieces of fiberglass in preparation of tomorrow’s layup.

Spar Box Inside FinishedMicro slurry’d the foam inside and added 1 ply of BID on the entire inside.  Added the inboard bulkheads, and added BID to both sides, lapping onto the sides.  Added the 3 plies of UND, then the LWA1, and added 1 BID.  Added 1 additional BID to the outboard bulkheads, lapping 5″, added the LWA1’s on each end, and covered with BID.  Added nails around the LWA1’s so they wouldn’t shift, and weighted down.  Added the center bulkhead and glassed both sides, lapping onto the spar.  I had micro’d the center bulkhead in place, like the rest of them, but for some reason, the plans say to flox that bulkhead in, even though none of the others are.  I will have to check with Dennis to see if it makes a difference.

Spar Box Cap glassed on Inside SurfaceTrimmed last night’s layup and drilled the 1″ holes in the interior bulkheads.  Covered the edge of the holes with dry micro.  In talking with Dennis, sounds like the “flox to connect the center bulkhead” was a type-o.  I slurried the inside faces of the fore facing foam, covered with 1 ply BID, and peel ply’d

Forward Face Micro'd to Spar BoxSanded the rough spots on the inside of the spar so that when I reach into the spar to add the wing attach bolts, I don’t cut up my hand.  Vacuumed everything and attached the top (forward) pieces, glass side down.  Added weight, and cleaned up micro leaking out the edges.

Traced and cut out the templates for the spar trough.  Then created a sanding block for the spar troughs.

Started sanding the top spar trough, but the template was not quite fitting over the spar.  It appears that when I laid boards along CS4 and added weight, it added some inward curvature, which caused the edges to have some gap which added some extra width when trying to lay the templates on the spar top.  Decided to wait until I could get a hold of Dennis before I moved on.

Spar Trough TemplatesIn talking to Dennis, it doesn’t sound like it should be a big deal.  Sounds like he uses the templates to drag back and forth to sand to the final shape.  In order to do this, I cut off the notch where they hang over CS4 (spar front).  Seemed to work pretty well.  Turned the spar over and repeated the process for the bottom.

Marked the locations for the LWA4 and LWA5 metal inserts, and routed out the foam down to the fiberglass of the inside layer.  Glad to see the center line mark for the inside layup showing through the glass.  Floxed the inserts in place and let cure.  Had some time left, so I cut out the shoulder harness blocks from 1″ x 1″ spruce, which will be inserted after the spar caps are done.

Sanded a radius on the edges for the shear web.  Micro’d the surfaces, and glassed 4 layers of UND at 45 degrees.  Finished with peel ply.  Trimmed the edges after cure.

Spar Trough Ready For GlassingCut out some 2″ strips of 1/4″ plywood and used as a dam for the spar trough.  Measured the trough size, and matched the height of the dam.  Screwed to the spar with drywall screws after predrilling.

Glassed the spar trough.  Glassed all 11 full span layers (maybe 12), and was able to get the sections at 64″, 61″, 55″, 40″, 36″, 32″, and 24″ from center.  I was not able to get layers in the 58″, 52″, 48″, 44″, and 28″ from center locations.  Not sure if I did not get the spar trough thick enough, or if the glass I used was just thicker than normal.  (The stuff I started with was certainly thicker looking)  I will have to get an opinion on that tomorrow.

Finished Top Spar CapAfter talking to Dennis (again), he verified I should try to get those layers in there (which I suspected).  After the first batch of layers was somewhat cured, I was able to run a bead of hot glue on top of my dams to add some height.  Added the missing layers in the spar trough, and added peel ply for final cure.

Trimmed the ends of the spar caps (top), removed the dams, and rounded the edge so UND will lay over later.  Turned the spar over, and added the dams to get ready for the next layup.

Repeated the spar cap layups for the bottom spar cap.  Finished with peel ply.  After cure, I removed the dams, cut off the ends, and sanded the edges to a rounded edge.


About Tarmac Grazer

I have recently purchased Cozy MK IV Plans #1627, and will be using this blog to log my build progress.
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2 Responses to 88.5 Hrs – Ch 14 – Main Spar

  1. Joe Person says:

    Hey Chad, was looking at the pics of the aileron bellcrank installations – FWIW, cantilevered rod-end installations on a single bellcrank are to be done with the bolthead against the face of the bellcrank that is opposite the face common to the rod end, at all locations where this configuration exists, regardless of the bolthead orientation relative to the airframe. See view G-G on P-16-4. This will also yield adequate clearance between the bolt and the inside face of the lower CS-127.

    -Joe Person

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