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  • June 19, 2018, 06:11:48 PM

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Author Topic: P-Force XL wing build  (Read 589 times)

Offline MikeyPratt

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P-Force XL wing build
« on: April 02, 2018, 11:15:38 PM »
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 glass 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
« Last Edit: April 10, 2018, 08:53:24 AM by MikeyPratt »


Offline MikeyPratt

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Re: P-Force XL wing build
« Reply #1 on: April 03, 2018, 08:32:44 AM »
First; Make up the four 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 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.
« Last Edit: June 12, 2018, 09:06:14 PM by MikeyPratt »

Offline MikeyPratt

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Re: P-Force XL wing build
« Reply #2 on: April 09, 2018, 04:16:53 PM »
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. 



« Last Edit: April 10, 2018, 06:00:41 PM by MikeyPratt »

Offline MikeyPratt

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Re: P-Force XL wing build
« Reply #3 on: April 09, 2018, 04:50:35 PM »
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..

« Last Edit: April 09, 2018, 07:36:59 PM by MikeyPratt »

Offline MikeyPratt

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Re: P-Force XL wing build
« Reply #4 on: April 09, 2018, 07:35:24 PM »
Left Wing:
The bottom wing spar needs to be shimed up 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 W-10 to W-1 and the rids.  Pay close attention to their placement.  Pin the alignment tabs 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.

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 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.
« Last Edit: June 12, 2018, 09:11:58 PM by MikeyPratt »

Offline MikeyPratt

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Re: P-Force XL wing build
« Reply #5 on: April 17, 2018, 11:02:41 AM »
Right Wing:
Built the right wing panel in the same manner as the left wing panel as shown in the previous steps.  Laminate the right W-1 wing rib to the left W-1 wing rib.  Block up the lower wing spars with the balsa scraps, add the remainder of the wing ribs making sure they are positioned and securely pined in place.  Note:  The wing will not be unpinned from the building board until after the trailing edge and some of the center section sheeting is finished. Install the inner 1/8” X 1” X 30” balsa leading edges on both the left and right wing panels and glue in place with thin CA glue (the leading edge will be finished after the leading edge sheeting is installed).   Place a length of making tape on top of the wing ribs behind the inner leading edge.  This helps protect the top of the ribs during carving and sanding the leading edge to shape.  Trim and sand the inner leading edge down to the top of the ribs.  Do not sand through the masking tape.  Replete this step for the top of the left wing panel.

Make up two full length trailing edges (Note: The trailing edges are joined together with a long scarf between the W-2 wing ribs as shown on the plan).  Remnember the trailing edge scarf joints are opposite from each other between the W-2 wing ribs when assembled.  Using a long straight edge make sure the trailing edge is straight and fits snuggly up to the wing rib alignment tabs on each wing rib before gluing in place.

Install the laser cut plywood bell-crank mounts (upper & lower) with thick CA glue.  Make sure the the bell-crank pivot hole are aligned by passing a 1/8” music wire pin between the mounts before gluing in place.
« Last Edit: April 20, 2018, 10:56:21 PM by MikeyPratt »

Offline MikeyPratt

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Re: P-Force XL wing build
« Reply #6 on: June 13, 2018, 07:32:43 AM »
This would be a good time to talk about bellcrank’s and leadouts.  I have used this type of bellcrank and lead-pout connections for years and never had a failure.  I know there are a dozen ways to do this, but I know it work great.

Begins by cutting twp lengths of 1/16” O.D. Brass or Copper tubing, and two .027 X 36” stainless cables.  Using a Sig 4” bell-crank drill out the ends of the outer arms with a


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