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Author Topic: P-Force XL wing build  (Read 2011 times)

Online 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: March 20, 2021, 04:01:41 PM by 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 »

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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 »

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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 »

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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 »

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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 thse 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 holes are aligned by passing a 1/8” music wire pin through the plywood mounts, making sure the music wire pin is vertical before gluing in place.  Add a 1/2” X 1/2” triangle stock to each end of the plywood bell-crank mounts for additional reinforcement.

BELL-CRANK
This is a good time to talk about bell-cranks and lead-outs.   I preference is the SIg 4” bell crank mainly because I like the way it handles the model with its positive feel and 4” length gives it good power for flight loads without being overly sensitive.  Below are a few suggestions to improve the installation and make sure there is no slop in the controls at neutral.

Drill out the center hole of the plastic bushings with a 3/16” drill bit to install a 1/8” i.d. Brass bushing.  The brass bushing should be a tight fit into the plastic bushing.  Place bushing into the bell-crank so the bushing sits on top of the raised bearing surface on the bell crank.  Using a long sanding block sand the B/C bushing and tubing until it’s flat with the bottom of the B/C.  Flip the bushing over and reinstall the plastic bushing, it should be flush with the raised side of the B/C.  At the outer ends of the B/C, enlarge these hole fron .0625 (1/116”) to .045 dia so there is room for the lead-out bushings to move freely when the controls are activated.

Tap the inner hole only of the bell-crack output arm with a 4-40 tap to install the ball-link at a later times during construction.  Note:  The outer hole of the output arm of the bell crank will be used after assembly to set the controls at precisely neutral.  In each of the bell-crank plywood mounts there are two holes, the B/C pivot hole is 1/8” d.i. And the neutral alignment hole is 1/16” d.i., after the bell-crank is assembled into the wing, place a 1/16” wire or drill bit by passing the 1/16” wire through the plywood B/C mounts and bell-crank to hold the B/C in the neutral position.  With the B/C held in the neutral position you can wrap the end of the lead-outs after the adjustable lead out guide and wing tips are installed on the wing assembly.  You will find that this is a really handy way to adjust the neutral of your model.
« Last Edit: March 20, 2021, 06:59:14 PM by MikeyPratt »

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Re: P-Force XL wing build
« Reply #6 on: June 13, 2018, 07:32:43 AM »
Begins by cutting twp lengths of 1/16” O.D. Brass or Copper tubing 2-1/2 inches long, (Note; if using hard brass you must remove the temper from the brass by heating each length of tubing until it has light red in color, then allow the tubing to cool),  Next, cut two .027 X 36” stainless cables, slip one of the brass tubes over the .027 cables with about 2” of cable past the brass tubing. Using a pin vise of about 1/4” dia. place the middle of the brass tubing over the pin vise and bend the brass around the pin vise.  Bend the brass tubing equally over the pin vise until you have two equal lengths of tubing.
« Last Edit: March 17, 2021, 10:17:51 AM by MikeyPratt »

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Re: P-Force XL wing build
« Reply #7 on: March 15, 2021, 06:28:15 PM »
Next, slip the newly formed bushing into the B/C making sure the bend in the bushing is centered.  (Note; you can make slight adjustments to the length of the bushing at this point).  Gently push the ends of the L/O bushings together making sure they are both equal in length.  Also make sure the .027 cable is at least 1” long, after wrapping the end of the B/C end, this will be folding over against the coils before wrapping the second round of coils at the B/C end.  Now we can add our fist set of copper coils to the wrapping.  Start by wrapping our copper wire around the two lengths of cable with  1/2” extra copper wire inside the brass bushing.  Keep the wraps touching each and tight as you can and finish wrapping the coil around the cables until the the wrap at least 3/4”.  Using a small set of needle nose players, you can grasp the cable and tighten the coil with your thumb nail by pushing the coil towards the B/C  Just make sure you don’t kink the cables doing this.  For reference, you can look closely at the photo you can see a finished lead-out cable attached to the bell-crank.

« Last Edit: March 17, 2021, 10:28:55 AM by MikeyPratt »

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Re: P-Force XL wing build
« Reply #8 on: March 16, 2021, 09:28:24 AM »
Now we can add our fist set of copper coils to the wrapping.  Start by wrapping our copper wire around the two lengths of cable with  1/2” extra copper wire inside the brass bushing.  Keep the copper wire wraps touching each other and tight as you can and finish wrapping the copper wire around the cables until the the wrap is at least 3/4”.  Using a small set of needle nose players, you can grasp the cable and tighten the coil with your thumb nail by pushing the coil towards the B/C  Just make sure you don’t kink the cables doing this.

« Last Edit: March 17, 2021, 10:24:04 AM by MikeyPratt »

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Re: P-Force XL wing build
« Reply #9 on: March 16, 2021, 09:34:57 AM »
Continue wrapping the copper wire for a length of 3/4” of and inch making sure all the wrappings are tight and touching the previous coils.  One again, if needed, slide the coils together with you thumb nail.  Next, bend over the excess of the cable and slightly crimp the the end of the cable so it fits flush on top of the copper wire coil, (make sure you are crimping the excess cable and not the lead-out).  Trim off the excess cable close to the end of the brass bell-crank bushing,   Next step, finish wrapping the second coil of copper wire on top of the previous coil, to securely lock the cable in place.  Continue wrapping this coil until you reach the end of the bell-crank bushing.  Tie off the end of the copper wire by twisting the two copper wires together.  Cut off the excess and bend the twisted wire into the end of the bell-crank bushing.

« Last Edit: March 16, 2021, 10:40:41 AM by MikeyPratt »

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Re: P-Force XL wing build
« Reply #10 on: March 16, 2021, 10:20:13 AM »
Carbon Fiber Pushrod,
Begins by purchasing the a 36” pushrod kit from Central Hobbies and the Titanium 4-40 inserts.  Very high quality products and well represented by many model builders they are great products.  I like them because the are light and very stiff (they do not need a pushrod support) and easy to assemble. 

Trim the the C/F pushrod to a length of 22” (wrap the pushrod with masking tale where you are going to trim off the C/F pushrod) the help prevent from splitting carbon shaft when cutting it off.  Sand the both ends with 220 grit sandpaper 1” back from the end to roughen the each end each of the pushrod.  Stick the end of the C/F tube into isopropyl alcohol and let it stand for a few minutes, this removes any residue of and molding release wax for a better bond between the C/F pushrod and titanium insert, and wipe off the insert as well.  Mix up a good amount of JB Weld and throughly mix the two halves of epoxy.  Apply the JB Weld into the end of the C/F tube with a toothpick reaching into the tube at least 1”, next apply JB Weld to titanium insert limberly on the end of the connector and install the connector into the tube.  Wipe off any epoxy that oozed out of the pushrod with a paper towel with isopropyl ilcohol.  Stand the push rod vertically and allow the epoxy to harden slightly.  Replete this process to attach the other titanium connector.  Allow the pushrod to set 24 hours to fully cure before use..

Wrap the ends of the pushrod and the last part of the connector to strengthen the ends with heavy weight thread and thin CA glue and allow to dry.  Install a 4-40 nylon ball link to each end threading the ball link onto the connector at least 1/2”.  Note;  Thread a Lock nut onto the treaded parts of titanium connector to measure the depth of the Ball link.  This is where people twist the ball link on too far on the connector and that binds the ball in plastic end of the ball link.  If the ball link is too tight at the beginning, “Don’t use it and replace it with a new one that moves freely.  Note: In the past, I’ve crimped the ball- joint with pair of pliers to free the ball within the plastic, it helped at first but in time it became stiff again and had to open up the wing sheeting and replace the ball-link.

« Last Edit: March 28, 2021, 11:22:40 AM by MikeyPratt »

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Re: P-Force XL wing build
« Reply #11 on: March 16, 2021, 11:26:43 AM »
Install the laser cut plywood bell-crank mounts (upper & lower) with thick CA glue.  Make sure the the bell-crank pivot holes are aligned by passing a 1/8” music wire pin through the plywood mounts, making sure the music wire pin is vertical before gluing in place.  Add a 1/2” X 1/2” triangle stock to each end of the plywood bell-crank mounts for additional reinforcement.

The bell-crank and least-outs can now be installed in the wing.  The bell-cranks is supported by 1/8” music wire (or optional 1/8” drill rod) through the plywood bell-crank supports.  Make a bell-crank support 1/8” rod that’s 2-1/2” long.  At one end of the rod cut a grove with your Dremel cut-off wheel, 1/16 from the end of the rod, slip a piece of silicone fuel tubing over the support rod and stand vertically in a vise or locking pliers, place a number two flat washer on the top of the support rod (make sure you have sanded the rod and washer to get a great solder joint), solder the #2 washer to the top of the support rod allowing the solder flow around and into the grove of the support rod to really lock and hold it in place.  Clean off the support rod by brushing off the flux and residue with Lacquer or dope thinner.  The bell-crank support rod can be slipped in place capturing the B/C in place along with the 1/8” i.d. x 1” Brass eyelets, Note: The large flared flat end of the eyelet goes agonist each side of the bell-crank   The bell-crank assembly should be centered between the spars with almost zero slop in the movement of the crank assembly up or down or side to side.  Both of my models required 1/32” plywood washers at the end of the brass eyelets and the bell-crank mounts.

Once satisfied with the centering of the B/C, solder a #2 flat washer on the opposite end of the B/C support rod using the same procedure that was mentioned previously. 


« Last Edit: March 28, 2021, 11:31:40 AM by MikeyPratt »

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Re: P-Force XL wing build
« Reply #12 on: March 20, 2021, 07:00:45 PM »
Install thse 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, use Tite Bond glue to glue the trailing edge in place.  Pin in place and allow to dry.  Using a CA glue seems to cause a ripple affect on the trailing edge between the ribs.  That’s why I like the Tite Bond better.
« Last Edit: March 28, 2021, 12:44:33 PM by MikeyPratt »

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Re: P-Force XL wing build
« Reply #13 on: March 29, 2021, 12:05:13 PM »
Finish the lead-outs by cutting two lengths of 1/4” heat shrink tubing that are 1-1/4” in length, slip the one piece of the heat-shrink tubing over the .027 cable to the bell-crank lead-out attachment and slider the heat-shrink tubing over the copper wire wrapping.  Using a heat gun, shrink the tubing in place to prevent the copper wire from unwrapping.  Allow it to cool.



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