Sunday, June 19, 2016

Tons of work accomplished


New bolt to support the forward cable guides:


Tail skid now more roundy.  All I did was rotate it 90 degrees and round it over slightly.

Rivets for the ailerons:

Added a tube to mount the seat:

Added the slots to mount the aileron crank plates.  I'm a bit sketched out putting slots into a tube like this, but was willing to give it a try because I can always remake the tube if I need to:

Working to replace this sketchy wing bracket.  This is the before picture.  Note the small distance between the bolt and the edge of the bracket on the left of the picture.

While I was replacing the strut bracket, it was time to work on the main load path in general.  The base tube (strut attachment though the nose) had holes for the strut brackets that meant I had to twist the struts during assembly to get the main pins to slip through the holes.  I remade the base tube (again) and mounted it to the nose.  It only took practically taking the entire nose section apart to get the old one out.  And then I spent a solid hour in the back yard aligning the struts and marking the holes before match-drilling the four holes one at a time.

After the strut carry-through was done, I put the seat back on.  Boy it looks good.  
 

And of course I sat in it and made airplane noises :-)   With the high edges, my hips are well supported, but I also can't get my feet on the ground anymore.


That's pretty much everything prior to a structural load test.  I'm debating a few options for what's next for that prep.  I can stay local and build a giant gazebo rig, or I can work on transportation to a large swingset a few hours south.  We'll see.


Cabanes:
  • DONE new cabane aft tubes with sleeves
  • DONE cabane compression braces (some are loose after the cabane rework from G3 to G4 design)
Control surfaces:
  • DONE glass the right aileron ribs
  • DONE flip fwd aileron control horn bolt to other direction ... and switch to AN3-13
  • DONE rivet aileron crank tube to trailing edge (G4S4)
Nose:
  • DONE aileron crank tube slots
  • change control stick axis bolt to drilled with cotter pin (will have to remove the torque tube)
  • sidewalls in forward nose section (G4N13) 
  • make a nose skid (G4N10)
Tail:
  • DONE AN3-26A bolt into the forward line guide bracket, replacing a rivet (G4T14)
  • DONE round off the tail skid to be more roundy than pointy
  • DONE swage aft cables (4x remaining) 
  • replace lower horizontal strut to tail connection bolt with a longer one
  • check all bolts are appropriate grip lengths
Wing:
  • DONE remake the wing strut bracket marked "replace" 
  • glass the ribs to LE and TE
  • stiffener for aileron control line 
  • leading edge shell (G4S9) ... the Colombian Goat uses a piece of sheet aluminum instead of foam
Miscellaneous:
  • wrap every pulley with tape and heat shrink to hold stiff and straight
  • threadlock on every quick-link
  • check every quick pin for elastic retainers are both present and correct length (several are just singles)
Buy list:
  • covering and adhesive
  • (1x) 1/8" SS quick-link

Wednesday, June 15, 2016

Removing blue tape

I'm marking known tubes or brackets or bolts that needed to be replaced with blue tape.  I knocked 5 off with the work last night and tonight: trimmed the tube to length and sorted out the mounting to the other end.  Also trimmed the lower cabane compression strut and added the two washer + rivet retention onto the new cabane.  I'm debating to not add the upper compression strut. 


The new u-bracket is 1-1/4" channel instead of 1" channel, and thus the cabane fits within the bracket without any ovalizing.  I'm trading a little bump in the covering for a lot less pain. 

For now, feels like it's done.  Done tonight anyway!

Back to tube work

Did a couple of hours' of work making new aft cabanes.  Started with a sleeve and a new bracket.



Probably will work on cutting them to length and mounting into the cabanes tonight.

Sunday, June 12, 2016

Mounting the seat

I took the seat to work to weigh it (4.062lb) and got a great suggestion to use hose-clamps to mount the seat to the cross-tubes. My initial thought was to put one at each end of the aft seat tube to provide best support.  However, those locations would have interfered with the control cables, so I went with a single clamp in the center. 

After cutting out the first slots and test mounting the seat, I marked the locations for the shoulder and seat-belts.  Those slots were cut with the Dremel using a burr and cleaned with a sanding drum.  The edges were generously rounded to prevent sharp edges from cutting the seat-belt (that will be an area of inspection).




After all that, here's the seat mounted.  Yippee, onward to the next thing.

Seat:

  • DONE seat mold body work
  • DONE finish the seat mold
  • DONE pull a seat from the mold
  • DONE mount the seat to the nose
Nose:
  • change control stick axis bolt to drilled with cotter pin (will have to remove the torque tube)
  • aileron crank tube slots
  • sidewalls in forward nose section (G4N13) 
  • make a nose skid (G4N10)
Tail:
  • AN3-26A bolt into the forward line guide bracket, replacing a rivet (G4T14)
  • swage aft cables (4x remaining) 
  • round off the tail skid to be more roundy than pointy
Cabanes:
  • new cabane aft tubes with sleeves
  • cabane compression braces (some are loose after the cabane rework from G3 to G4 design)
Wing:
  • glass the ribs to LE and TE
  • stiffener for aileron control line 
  • leading edge shell (G4S9)
Control surfaces:
  • glass the right aileron ribs
  • flip fwd aileron control horn bolt to other direction ... and switch to AN3-13
  • rivet aileron crank tube to trailing edge (G4S4)
Miscellaneous:
  • wrap every pulley with tape and heat shrink to hold stiff and straight
  • threadlock on every quick-link
  • DONE neoprene eyebolt spacer: horizontal stab (G4T8), elevator control arm (G4T16), tail strut (G4T19)
  • check every quick pin for elastic retainers are both present and correct length (several are just singles)
Buy list:
  • DONE 1" wide fiberglass tape (I ran out on the aileron, also needed for the ribs to LE/TE joint)
  • DONE (1x) AN3-26A for fwd tail line guide (G4T14)
  • DONE (2x) AN3-13 for aileron fwd control linkages
  • nose skid plastic plate
  • covering and adhesive
  • (1x) 1/8" SS quick-link

Wednesday, June 8, 2016

I waited until Thursday to pull the seat, yeaaaah

The seat has been curing on the mold since Sunday evening.  Tonight, it was time to come off.    Patience is a virtue I do not always possess.  But it's likely Thursday before you get a chance to read this anyway, so I waited long enough as far as you know ;-)



After removal of the consumables (breather and perf), I ran a screwdriver around the edge and got a good release locally between the seat and the mold.  It took extra long popsicle sticks and compressed air to start making a reach toward the center.  I might have whacked at the chair with the rubberized end of a screwdriver to help the release too; definitely can hear a change in the tone from a pop to more of a thud when the release happens.  After maybe ten minutes, the sound everyone who has molded knows well: pwoosh as the part releases and gets a rush of air as the surfaces separate for the first time.




Verdict: it's awesome.  Lighter than the plastic, way stiffer than the plastic, and the new features worked out super well.  It appears to fit on the Goat nose frame just dandy, and the relief for the control stick is plenty large for full range of stick motion.  The stick hits my legs well before it hits the seat. I need to get it to a scale I trust before posting weight numbers.  It'll just get lighter when I make holes for the side and should belts.

Enjoy some more pictures!




Sunday, June 5, 2016

I'm going to finish the seat today

A couple weeks ago, I figured the filling process was over and it was time for a coat of primer.

With the color of grey applied in many thin coats, I let it dry a day and tried to start sanding.  I burned through a couple sheets of 220 grit wet paper, then went away for a week on vacation.  Coming back and starting to sand again, it was WAY more cured and didn't clog up the sandpaper anymore.  Note to future self: let filler primer cure for a week before starting to sand it.

The main point of primer is to provide a consistent color to see where high and low spots are by changing color during block sading.  Usually you're not supposed to sand through the primer.  And of course I did, without going back for another coat, which I should have.  I'm getting a bit impatient with the seat now.


After sanding to 600 grit, I decided the flexibility of the plastic seat would probably allow a reasonable release without sanding to a more typical 1500-2000 grit.  So I cleaned up with isopropyl alcohol to remove any debris and to dry out the water.  After waxing the mold three times (well, at least two in every place), letting it dry 30 minutes between coats, and dry for five hours, I gave the mold a coat of PVA mold release before going to bed last night.

Last night I also cut a bunch of material.  The final layup will be epoxy gel-coat (cabosil thickened and white-pigment dyed epoxy), 1.4oz fiberglass, two layers 8.7oz 8-HS satin (style 7781), 2mm Lantor Soric XF, two layers 8.7oz fiberglass.  The edges will get three additional layers of 8.7oz to transition between the cored and uncored regions.


The Soric XF patterns were used to cut perforated release film (perf).  I don't see need to use peel-ply on this part since I shouldn't need to bond to the backside.

Commitment started this morning at 0930 with the first gel-coat layer.  As soon as I started, the realization struck that I really should have put down a layer of white paint first.  I'm starting this like a mold, not a flight part, and a flight part really is benefited by a coat of paint to make a consistent color without excess epoxy weight.  With the method I've started now, I'm not sure if the 1.4oz surface layer with pigment will really make a consistent color.  Oh well, I can repaint it afterwards if the color is ugly.  For now, I'm waiting a couple hours for the gel-coat to tack up where it doesn't hold a fingerprint.

After 8 hours straight of layup and who knows how much epoxy, here's the perf going on (when I had clean hands)...  I'm sure the first gel-coat layers were fully cured before this point.  It would have been helpful to have stickier epoxy when putting the Soric on to keep it held in place.  It stays when there is a lot of epoxy in it, but that's defeating the point of saving weight. 

Another hard part was using a small acid brush for the gel-coat layers instead of the 1" horsehair brush.  The 1.4oz glass is frustrating when trying to keep from getting stuck in the gel-coat layer, even with a first layer of raw epoxy to wet out the surface, and the small acid brush is too tiny for a massive project like this.  When switching to the first layer of the 8.7oz 7781 and wetting out with a 1" horsehair brush, it was IMMEDIATELY better.  I probably could have skipped the 1.4oz layer in all honest with the high thread-count 7781, and it went down very nicely and at a much faster pace.
 

I decided to put the whole chair in a bag instead of sticking down to the old chair given its several holes had been patched.  A simple twist of the mold and the chair popped off the Bondo supports.  A rather large 3m x 1.5m length of stretchlon and yellow bagging tape made a workable bag.  The whole chair was stuffed in, bag sealed, and the vacuum started pulling the bag down nicely.  After a few minutes and pushing/massaging the bag into the corners, the perf was starting to show epoxy coming through to the breather like it should be.


I'll let this sit under vacuum at least through tomorrow morning and leave it on the mold until Thursday evening.  Definitely don't want to rush this part.  It needs to shrink while held onto the mold, rather than in free space.

That's all for today.

Wednesday, May 18, 2016

Wax on, Wax off

I wish the title were referring to actual wax.  Nope, still doing body finishing work.  Spray paint on, sand off most.  Fiberglass and epoxy on, sand off most.  Now glazing putty on, sand off. most  I have more than a few more rounds of sanding to go and spray paint to go.  It's going to pay off though when the parts releases easily from the mold and doesn't need much of any finishing work.

Wax on (glazing)



Wax off (sanding)


Much more sanding to do.

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