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P-Force XL wing build

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MikeyPratt:
First subject to this post, make sure your building surface is flat.  People always tell me their table is flat, guess what? Most are not flat!!!

Get the longest straight edge (72) you can find from your local Hardware Store.  Place the straight edge (on edge) on the building surface length wise, check the center of the straight edge and see if there is a gap between the surface and the straight edge. If there is a gap, place paper shims under the surface until there in no gap under the straight edge.  Next, place the straight edge from corner to corner again checking for gaps under the straight edge and building surface.  Now do the same thing on the opposite end of the building surface.

LASER CUT PARTS:
Remember that these parts are laser cut and are cut to very accurate outlines.  Just to give you an example, the laser follows a drawn line from a computer and cuts a .008 line down that drawn line.  The laser beam is focused on the middle of that line leaving you with a part that is slightly under sized .004.  The computer program can be adjusted to compensate for this but most cutters don't do that.  One swipe of a sanding block can do more damage to the accurately of the laser cut part.  So don't sand off the discolored edge of the parts.  Note: some of the exterior grade plywood make more smoke from the glue that bonds the plywood laminates together.  By all means sand off as much of the soot off these parts as possible for good glue penetration.

MY BUILDING BOARD:
1-1/2” X 24” X 72” in length butcher block from Sears.  Glass top 1/4” X 24” X 65” tempered glass from your local glass company.  Cover the top of the glass with a piece of Celotex from your local home improvement store.  This board allows you to build directly over plans and push straight pins into it to securely hold parts in place.   This is about as close as you can get to a flat building surface for the least amount of money spent.

I like to have all the needed parts ready for assembly before starting to assemble the wing.  Have the weight tip box, leadout guide, bellcrank & leadout cables, and wing tips assemble and ready to go

MikeyPratt:
First; Make up the four needed wing spars by gluing the spar doubler to the upper and lower wing spars.  The wing spars and spar doublers are made from 1/4” square balsa, the length of the doublers are 14-7/8”.   Using a long straight edge for alignment, pin the spar to the work bench and glue the spar doubler to the spar.  Taper the inside edge of the spar doubler from the wing rib W-5 to W-6. The taper should go from the outside of W-5 at 1/4” to the inside of W-6 at 1/32”.
The end of each spar and doubler need to be angled at the correct angle.  The design of P-Force XL is intended to be built with out the added cost of an additional wing rib.

MikeyPratt:
Locate the the Spar Angle Guide (SAG).  Place the SAG on the face of the spar and spar doubler.  The guide must be flush with the top of the wing spar.  Using a soft lead pencil, draw a line onto the spar and spar doubler along the face of the angle guide.   During the assembly, this smal angle allows the spars to match and fit flush when building the opposite wing panels. 

MikeyPratt:
Using a long sanding block with 220 grit sandpaper, sand the end of the spar and spar doubler down to the previously drawn line.  Make sure the end of the spars are 90 degrees to the sides of the spare and spar doubler..

MikeyPratt:
Left Wing:
The bottom wing spar needs to be shimed up off the building board before placing the wing ribs in there proper position.  Place a scrap of 1/16” balsa under the spar at the W-1 wing rib and cover with a small piece of wax paper.  Next, place a 1/4” X 1/4” X 1” balsa scrap just out side the W 10 wing rib and under the lower wing spar.  Next, place a 1/8” piece of scrap balsa under the spar between W-6 and W-7 wing ribs.  Pin the lower wing spar in place over the balsa shims to hold the spar solidly in place. Working from tip, incert the wing ribs W-10 to W-1 and pin ribs in place.  Pay close attention to their placement and alignment.  Pin the alignment tabs of the wing ribs to the building board with two pins, one from each side of the alignment tab.  Use the provided 90 degree triangle to make sure each rib is 90 degree and square to the building board and spars..

Add the laser cut trailing edge and leading edge reinforcements (Note: The outboard is shorter than the inboard), along with the top wing spar. Note: You will notice we haven't glued any thing yet.  At this point make sure everything is square and is in proper alignment.  Check the alignment with a long straight edge making sure all ribs contact the straight edge, and then sight down the trailing edge.  If they don't, find out why and correct the problem before gluing the parts.  Once you are you are confident with the alignment, place a single drop of thin CA glue to each joint.

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