FRED #528 construction log

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  1. Jul 29, 2015 #181

    Abraham Leket

    Abraham Leket

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    DRW2+DRW19-Main spar & F6 fittings and gussets: the strenghten 1" extra diagonal is glued and its clipped end is used to strenghthen the adjacent upright member like so:

    P1010731.jpg

    We use the pre-cut F6 fittings holes (DRW19) as drill guide-and drill the (3) 1/4" holes in the upright (1) and diagonal (2). We have to drill before the 10" gusset covers the whole area and we lose the exact location of the holes ( note that the lower hole is EXACTLY in the middle of the upright slightly below the spar top 1" capstrip surface.
    Note that the 1/4" intra rib filler is not yet glued to the bottom 1" capstrip and you have to take that filler into account while adjusting the lower 1/4" pip-pin hole.
    Orientation- the picture depicts starboard spar (The plan shows port spar).
    P1010732.jpg

    The spar is now mated with its vertical web 1/16" gussets. I'm using resourcinol for this type of lamination- Only 3 Oz (85 grams) is all that it takes for back and front (single) spar sides i.e-6 Oz for complete spars gussets job. T88 would have taken much more since the gussets need glue on ALL its bottom surface that comes in contact (resourcinol has watery consistency thus easier to spread).
    Do not forget to drill the front 10" gusset F6's holes through the pre-made holes before glueing the back 10" gusset-or you will lose the F6's hole locations. BTW-This area need to be 1/8" packed out further more- later on.)
    P1010733.jpg
     
    Last edited: Jul 29, 2015
  2. Aug 4, 2015 #182

    Abraham Leket

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    DRW2- Patching rib stations and other issue:: Rib 1,7,10 are stationed on the main spar on 1/16" pre-glued gusset.
    In order for ribs 2,3,4,5,6,8,9 to have the same mutual leading edge datum it is necessary to patch 1/6" ply (1" squares) on the spar top & bottom (front side only) every 12" like so:
    P1010734.jpg

    Safety issue- The plan does not show any means of securing the lower wing 1/2" pin from moving. A 1/8" hole in the pin and a 1/8" steel R-clip will make flying much relaxed.
    P1010736.jpg
     
    Last edited: Aug 4, 2015
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  3. Aug 4, 2015 #183

    Abraham Leket

    Abraham Leket

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    DRW2-Complete 2 main spars: From July 13th till Aug 4th- 2 hours a night-thats 46 labor hours and I got 2 main spar job complete with all fittings tests, gussets and packings ready to be varnished.
    Total view for a complete starboard spar (all the redish color-Resorcinol Formaldehyde glue (Cascophen):
    P1010737.jpg

    Next-Rear spars.
     
    Last edited: Aug 5, 2015
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  4. Aug 7, 2015 #184

    Abraham Leket

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    Managing raw material left-overs and rear spar construction: ply sheet 24"x48" 1/16" costs $20 before shipping charges and FRED need 2 dozen half sheets to build so.. we cannot just cut parts and get rid of 30% left over ply to scrap.
    We need the long 6" strips left overs to build vertical web gussets that the plan calls for. Now- vertical web does not come by easy- its the short 24" side of the half sheet.
    In order to economize quantity usage we turn into the main source of vertical web ply- the 1/16" ply for the wing D-Box construction. For that task the plan calls for (8) half sheet 1/16" ply.
    The EXACT measurments for constructing the D-Box is 18" top cover plus 16" bottom cover- converging at the 1/2"x1/2" leading edge spruce strip.
    By pre-cutting the 24"x48" sheet to 18"x48" and 16"x48" we are left with (8) vertical sheets (6" and 8" by 48") and THEY are the main source for vertical sheet requirements (large gussets for the (2) main spar and laminating the back side of (2) rear 115" spar) .
    The pictures below depicts the method of constructing the wing rear spar- but first a word on shipping costs- The plan calls for 115" 3.25" spruce spar quality pieces and shipping ANYTHING above 108" is done by trucks and $150 extra shipping charges (thats just for US shipping and if you live in Europe- the charges quadruple.
    What to do? simple- order 10' pieces and ask the vendor to cut 12" ends off, wrap the cutting separatly and send it all (this time economy ;)-short (12") on top of long (108") - and at home-do a little 1:10 scarfing. The wing tip side scarfing (to 115") is like so (you are looking at $150 piece savings so..give it a LIKE !):
    P1010742.jpg
    The vertical pieces for the rear spar are laminated in 6" and 8" seperate pieces with 5 Oz (140 grams) of resorcinole glue (Cascophen) or T88 (50% more expensive per weight..) and about 150 staples like so:
    P1010740.jpg , P1010741.jpg , P1010738.jpg
     
    Last edited: Aug 7, 2015
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  5. Aug 12, 2015 #185

    Abraham Leket

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    Packing out rear spar roots: The plan calls for 7/8" total wood area under "D" and "D1" rear spar fittings. The 1/2" spar and its 1/16" vertical web ply were already constructed so we need an additional 1/4" ply (vetrical web) on one side and 1/16" ply to augment the 1/16" on the other side- thus we achieve that 7/8" packing. Note that the packing edges are filled to gradient (this is aviation correct wood doublers method and practice) like so:
    P1010744.jpg
     
    Last edited: Aug 12, 2015
  6. Aug 17, 2015 #186

    Abraham Leket

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    DRW9-Outer wing rear spar adjustment[/B]: we clamped "D" and "D1" fittings to a scrap 3.25"-1/2" wood to test the rear spar location such that the first wing rib that will be attached to the spar will be flush against the center section outer skin (keep in mine that the rib has 1/4" upper and lower members. Another thing-its much easy rotating 1oz wood then work straight on the rather heavy spar:
    P1010746 (2).jpg
    Once the fit is achieved we copy the markings and distances from the scrap wood onto the spar packing and drill the spar straight using this lovely $35 drill guide. Without it-there is no way you will get a 100% fit for the metal fittings-its a must tool:
    P1010748.jpg
    The 1/4" construction bolts are inserted . We can see the spar, its packing and the "D" fittings set and (non-standard) construction only 1/4" bolt set-they will be replaced by the right shank AN bolts later :
    P1010749.jpg
    The whole spar is checked again for a fit (note that the spar will get an additional 1/4" rib upper and lower member- thus we get the full fit flush with the center section outer envelope):
    P1010752.jpg
     
    Last edited: Aug 17, 2015
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  7. Aug 18, 2015 #187

    Abraham Leket

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    First rib alignment- we connect the (2) spars to the center section fittings and we slip on the base rib 1.5" away from the center section and check EOA (the fish eye camera distorted the right side- FRED's fuselage is not that warped:gig::
    P1010753.jpg
     
  8. Aug 23, 2015 #188

    Abraham Leket

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    Scaffold the wing spars: Fred's' 1:5 extremely short aspect ratio wing can best be constructed by actually build it on the fuselage itself- the main spar attached and immediately you get the length and the dihedral build in and the rear spar (attached to a swivel joint) is supported on its lower side by a stand (see red stand) and aligned perpendicular to the main spar using 3' threaded steel rods and nuts. You measure the exact root position distance (main to rear spar) and copy that to the rest of the spar length using the nuts to dial in the distance like so:
    P1010754.jpg
    The rods are attached in such a way that we can slip on the ribs later on without effort while the rods are pulled out and re-attached after the rib passes their stations ( two scaffold rods are always attached at any given time to maintain even distances, we remove only one rod at a time when the rib is passing its station and re-attach it back after the rib pass its location) .
    The following (2) pictures depicts the main spar scaffold attachment and the rear spar scaffold attachment points.
    The main spar attachment (picture below) is lightly T88 glued to the inner side of the main spar. The rear spar attachment is also attached-but with (2) wood screws also to the spar inner side-so we can remove and re-attach the scaffold rod during rib attachment process and by re-attaching the rods you maintain the whole wing integrity and keep all distances even.( Needless to say- the (3) scaffolds and the attachment will be removed after the wing is finished (that is why we apply only thin T88 glue on the main spar attachment points. One light hammer hit-and its out )- their task is to provide constant scaffold pressure and eliminate spars "spread eagle" on us- thus the ribs are not under undo forces that might also warp them):
    P1010756.jpg
    The rear spar attachment:
    P1010755.jpg
     
    Last edited: Aug 24, 2015
  9. Aug 24, 2015 #189

    Abraham Leket

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    Dial in wing Washout: The plan suggests 2 degrees washout and at this point its nothing more than raising the rear spar with the adjustable support to a point where the angle of attack measured at the tip area is 2 degrees less than the angle measured at the root. The ribs will be glued to a pre-set condition thus we get a solid gradual washout (not by raising the ribs trailing edges tips but by raising the rear spar-and that is the correct way of doing it):
    P1010757.jpg
     
    Last edited: Aug 24, 2015
  10. Aug 26, 2015 #190

    Abraham Leket

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    Slip on regular ribs #1 to #6: The first 6 ribs set (regular type) are sliped on the spars with very little filling- the scaffold keeps the spars aligned and at 2 degrees wash-out and we staple them onto the spars -top and bottom. There is realy no need to glue them yet- the upper & bottom 1/4" spruce fillers will be glued and they will lock the ribs in place.
    Aileron type set (#7 to #9) will follow and the aileron spar will be inserted-all in the next post:
    P1010758.jpg
     
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  11. Aug 31, 2015 #191

    Abraham Leket

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    Aileron ribs #7 to #9 and aileron spar: the aileron 1/2" x 3"x 47" spruce spar gets 1/16" vertical web ply on its inner side and the spar is slide inside #7 to #9 ribs.
    1" wood bar is clamped in between the rear spar and the aileron spar to maintain clearance for the hinges.
    P1010762.jpg
    The whole frame will receive 1/4" x 1/2" and 1/4" x 1" fillers in between the ribs to lock them in place
    Next post will be on the ribs packing.
    P1010763.jpg
     
    Last edited: Aug 31, 2015
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  12. Sep 4, 2015 #192

    Abraham Leket

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    Checking and marking AN bolts: Its always nice to receive the package from the vendor- but before you spread the bolts all over here is a VERY good advice:
    When ordering the AN bolts (size, shank, drilled, undrilled etc)- get a plain paper worksheet and write down which section in the aircraft receives what vendor's LOT number (to be ordered ) and keep the list handy- until the goods arrive (see picture right side for the list).
    Example: you need to order AN5-15. The vendor's LOT number is 10787-5 and you add a description in the worksheet: "10787-5=bolt for the eileron swing arm".
    When opening the box-get your worksheet and pull out each small envelope at a time- make a reference to the vendor's LOT Vs. your worksheet description and lable the envelope in masking tape. Write in plain english where it should go. NEVER open the vendor's pre-labled envelope unless you are standing in front of the task ready for the job and you have the right size and number of bolts needed - inside the envelope. That way you will not end up with strange left over bolts and you go :"..Hey wait a minute- the bolt in section X was short a little...it should have been THIS one here" , etc etc etc- we all been there- now this eliminates the confusion (the yellow masking tape carries the description where to put, you can even draw a small picture -you not going to believe how stupid we are 7 weeks after ordering..):
    P1010764.jpg
     
    Last edited: Sep 4, 2015
  13. Sep 14, 2015 #193

    Abraham Leket

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    Securing the ribs & fill the gaps: The plan calls for strips of 1/4" x 1" to fill in the gaps in the main spar (top & bottom) and strips of 1/4" x 1/2" for the rear spar. We start by cutting the spruce strips -stack them to 10 equal bundles for each rib section (and there are 10):
    P1010765.jpg
    The glueing process takes (4) Oz of T88 for each wing- we drench the main spar with it-this also seals the main spar top & bottom cap strips (staples are the best for this job):
    P1010766.jpg
    We secure the aileron spar to the ribs by using 1" spruce triangles glued to the ribs outer 1/16" gussets and the aileron spar while maintaining 1" gap tight with clamps (the gap is for the hinges). The aileron will be cut off from the wing ONLY after we glue the trailing edges and the D-box up front:
    P1010767.jpg
    The port wing minus its wing tip section is now completed. We commemorate 2 years in the leisurely making of all wood FRED -80% done -needs another 2-3 month to produce the trailing edges ,compression struts, wing tips, starboard wing assembly (main spars & ribs are all ready done) , D boxes ply covers, and wing metal struts-all will come next (in that order ) in this log.
    FRED's airframe can be completed in about 2 years at an easy going pace (8-10 hours a week)- it was even done in 1 year by somebody in the past- but thats just sacrificing family time-bad deal:
    P1010769.jpg
     
    Last edited: Sep 14, 2015
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  14. Sep 19, 2015 #194

    Abraham Leket

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    Rib #5 & Rib #9-Doublers Since the ribs are spaced every 12" and the D-box 1/16" ply sheets comes in 48" sections -we need to double rib (#5) and rib (#9) to serve as glue platform for the 1/16" ply sheet ( 1/2" white Pine will do the job- no need to go fancy here).
    We cut the false ribs with a router (the easy way) or you can cut and file with vertical saw and a sander-either way- it should match the full ribs (#5) and (#9) nose section. The tail end of the false ribs (that reaches out to the main spar)- will come later on.
    The false ribs are cut ((2) for each wing):
    P1010770.jpg

    And glued to the ribs (#5 & #9) inner side like so:

    P1010772.jpg
     
    Last edited: Sep 19, 2015
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  15. Sep 26, 2015 #195

    Abraham Leket

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    Trailing edge construction: Takes 3 seperate steps -each step requires a complete T88 drying time .
    Before construction begin- we need to bevel the 1"x 1/2"x108" spruce TE to a triangular shape like so: (a router is a good tool to do it- I've decided that a six-pack to the local carpenter works even better..):
    P1010778.jpg
    We pre-cut (24) 5"x4" x1/16" full gussets (web parallel the rib datum) and (12) 5"x 4"x 1/16" half gussets-same web direction. We start by glueing the gussets to the lower ribs like so:
    P1010773.jpg
    After the glue is completly dry we can lay the trailing edge and fit it to the ribs end. A little filling and/or 1/16" ply shims added to the ribs creats a full contact with the TE. We glue the trailing edge to the bottom gussets:
    P1010774.jpg
    After the glue dries we glue the top gussets but ONLY to the top edge-the binding process (to glue the gusset narrow side side to the top ribs side) will follow AFTER the glue is completly dry-see the gussets rises due to the TE pre-beveling:
    P1010776.jpg
    After 24 hours we can bend the gussets to the top rib end (remember-this done against the web direction so a good clamping is required) using a combination of clamps and staples like so. You can now see why it is mandatory to glue the wide gussets side first and let it dry. I dont think a 2 front battle with the gusset is a wise thing to do (TE done):
    P1010779.jpg
     
    Last edited: Sep 26, 2015
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  16. Sep 28, 2015 #196

    Abraham Leket

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    DRW14-Aileron inner bell crank unit: we use AN6-37 as the pivot pin for the bell crank. Its inserted into a steel bushing inside the main spar like so:
    P1010782.jpg .
    The pivot pin on the inner side will accept a 1" steel spacer to allow bell crank clearance. We also switch (4) 1/4" bolts sides to give an extra 1/4" clearance (head side Vs. bolt side) like so (lower picture shows it better):
    P1010781.jpg
    Finally- the aileron bell crank is inserted on the AN6 pivot bolt +castle nut and split pin and checked for clearance. FRED has folding wings and the bell crank needs clearance to receive its mate in the center section (pulling one pip-pin out and we can safely fold the wing minus the aileron system that stays tight inside the wing outer panel-see 1/4" bolt (in the right light blue arm) that serve as a temporary pip-pin):
    P1010780.jpg
     
    Last edited: Sep 29, 2015
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  17. Oct 9, 2015 #197

    Abraham Leket

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    DRW2+DRW14-Aileron Horn & Pullies-before constructing the pressure spar we need to varify that the aileron cables have free movement inside the ribs from root-to pully and for that we have to construct the whole aileron cable system. we begin with the 5/8" ply horn made out laminating (2) 1/4" ply+ 1/8" ply. The (2) 3/16" I/D steel bushing are inserted too.
    (2) 1" spruce triangls are glued to the horn before its mounting onto the aileron spar like so:
    P1010783.jpg

    The Pully brackets are constructed out of 18G steel, primed and installed at an angle to receive the 3/32" cable that comes at an angle from the root horn like so (a thread is used to simulate the 3/32" cable):
    P1010784.jpg

    The horn is now glued to the aileron spar. We make sure the horn mid-point is aligned with the pully cable exit point (Resorcinol glue was used throughout the process. I think that the inner wing chamber can get up to 140F and even more in the desert summer and epoxy can get soft at such temperatures):
    P1010785.jpg
     
    Last edited: Oct 9, 2015
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  18. Oct 23, 2015 #198

    Abraham Leket

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    D-Box construction – Unlike the sheet metal bending process were each hole is drilled at a time, clecoed , the sheet is stretched further, clecoed etc., thus transferring the pressure to the next hole (stressed skin method)- the plywood skin has to be glued whole sheet at a time- nothing to hold and gradually transferring pressure to the edges- in short- delicate job indeed since 1/16" ply tends to warp.
    This is how I've made it- 100% wrinkle free :
    Front leading edge 1/2"x1/2" spruce cap is first glued (resorcinol) to (4) sheets : (2) 1/16" ply- 48"x18.5" on top, and (2) 48"x16" on bottom-the cap serves as a bonding plate
    . P1010786.jpg
    One word of advice- 1/16" Ply comes in either 48"x48" or 48"x24" sheet sizes. The only difference is the shipping cost- the whole sheet 48"x48" cost more than the ply itself when it comes to international shipment. So this method of (4) separate sheets is cheap and works just as well as a fancy (2) wrap around 48"x34.5" sheets.
    After a good 48 hours (October..) -this "contraption" is glued to the ribs leading edge slots with its (4) half sheets hanging like so:
    P1010788.jpg
    P1010789.jpg
    P1010787.jpg
    After 24 hours we apply T88 to the inner ribs, wet the lower top sheet side with hot water (only 2" at the datum-NOT the whole sheet-see picture below) on its outer lower side (the non-glue side) We bend the top sheet using staples as we press the sheet against the ribs . Before moving on to constructing the bottom ply sheets we remove all staples from the top sheets and varnish their inner side.

    Lower sheets: as with the top sheet procedure we start by hot wetting the sheet root 2" datum area like so:
    P1010791.jpg
    The lower sheets may need a simple pressure jig to press it against the rib (the jig is also good for the upper sheet installation). The jig is not more than 1" spruce plate (vertical web direction) and we copy the rib leading edge onto it and cut its outline. We use the jig inner part' mark the middle leading edge datum to make sure we position the jig right (see below) and (2) clamps - starting gluing from the middle sheet position, staple and continue working our way out one rib station at a time (alternate left and right from center as you go) using the jig and its (2) clamps to press the sheet at the leading edge nose. This method eliminates pressure build-up and the creation of a "wave" on the sheet.
    P1010793.jpg
    P1010797.jpg

    When done-varnish the lower ply sheets inside and out. An inspection panel can now be cut in the D-box ample root area- this allows fueling tools to be stored (small funnel, plastic hand pump, etc) plus gives a super clear view of the root fittings condition-when inspected like so:
    P1010798.jpg
     
    Last edited: Oct 23, 2015
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  19. Nov 2, 2015 #199

    Abraham Leket

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    Two years in the making of FRED- needs the starboard wing and the airframe is complete. The garage is only 4.5 meter by 5.5 meter still-enough to do the job and
    store FRED after completion (wings folded).
    On the right- myself .

    P1010802.jpg
     
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  20. Nov 11, 2015 #200

    Abraham Leket

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    Pressure (Drag) Spar: For all intents and purposes this task should be treated with equal respect as constructing a main spar and should be treated as such i.e- no "modifications" and variations in materials and/or methods. In short-as planed it to be by the designer ( in DRW 8).
    Keep in mind that the spar is smaller than the ribs- its actually inserted in between ribs #2,#3 internal cross members and connected with (4) 1/2" spruce triangles to the rear and main spar. When position the pressure spar we make sure its bottom 1" square spruce member is flush with the bottom #4, #3,#2 ribs lower members. The upper spar member will be augmented with spruce blocks to match the ribs upper members thus we achieve a smooth and continues pairs of glue surfaces (upper and lower platforms) for the future 1/16" ply root skins-later on.
    Building process in pictures:

    We start by positioning the spar upper and lower 1" square spruce members and their spruce end points spruce blocks. This is the right time to check the free passage of the aileron cables through the main spar-to-drag spar 9.25" spruce block:
    P1010803.jpg

    We make sure when cutting the ribs #2 and #3 lower members (to let the lower spar 1" member go through) that we support the rib area with gussets before cutting- so we do not loss the ribs all important lower chamber design:
    P1010810.jpg

    We place in inner 1"x1/2" cross members in between the drag spar upper and lower 1" members:
    P1010805.jpg

    The Drag Spar upper 1" beam is augmented by spruce blocks (glued with T88) and a strip of 1/16" (as glue platform for the future 1/16" upper skin) to achieve an equal surface with the ribs upper members. The picture depicts the drag spar (left to right) in between ribs #3 (left) and #2 (right). Note that the drag spar upper and lower 1" members (at this point still without its gussets supports) are now flush with the ribs upper and lower members:
    P1010807.jpg

    The next picture depicts the lower drag spar member with its gusset supports (glued with reddish resorcinol-yes-the very glue that constructed the WW2 DH Mosquito)) and positioning with a rib lower member:
    P1010811.jpg

    After Drag Spar gussets are dry- the (4) 1/2" spruce triangles supports are glued in the main and rear wing spars intersection points with the drag spar (note the simulated aileron wire- a thread- and the passage throught the drag spar hole inside its 9.25" spruce block):
    P1010808.jpg
     
    Last edited: Nov 11, 2015
    Taiser, jmt1991, cluttonfred and 2 others like this.

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