Friday, April 29, 2016

A seated situation

Seat progress took two directions and I'm having to down-select. 

The EC Goat guys graciously sent me their seat profile so I could make adjustments from a good starting point and make it my own.  Fortunately for everyone, they hope to release the whole CAD package at some point in the future, to include their seat, so that will be awesome.

The other seat path was recommended by Jeff, finding a go-kart seat.  For $25 + $35 shipping, I found a roto-molded polyethylene seat from BMI Karts in Ohio.  The seat came in a huge box and weighed about fifteen pounds stock.  While quite comfortable, it didn't sit (har har) well on the Goat nose, so the big question was what to do with it. 


My original thought for the seat was to pull a mold off of the outside surface.  Instead, the inside surface should be smooth, given the manufacturing process.  That also would mean there is no extra part to manufacture either, just prep the inside of the front half.  So the first step was to take a brand new seat and cut it in half.  After an hour with the oscillating saw, and a mess of plastic debris, it was in half.  The edges still need more cleanup to make sure there is no negative draft around the edges, and I'd like to support the lip a bit better with a parting plane.  It'll be a while to set all that up, perhaps over the remainder of the weekend.  The inside surface is indeed smooth.  Awesome.



The most important part was to check the fit of the halved seat to see how it fits on the Goat nose mounting tubes.  This will take a little massaging, but is going to work well.  It fits down much lower into the seat tubes and I'll be able to bolt it to the tubes for solid structural attachment.  Quite happy with this path as the right path forward.  (I'll take a better picture tomorrow)



There are just a few items left:

  • change control stick axis bolt to drilled with cotter pin
  • flip aft aileron control horn bolt to other direction
  • rivet aileron crank tube to trailing edge (G4S4)
  • round off the tail skid to be more roundy than pointy
  • new cabane aft tubes
  • cabane compression braces (some are loose after the cabane rework from G3 to G4 design)
  • AN3-26A bolt into the forward line guide bracket, replacing a rivet (G4T14)
  • aileron crank tube slot
  • make a nose skid (G4N10)
  • glass the right aileron ribs
  • glass the ribs to LE and TE
  • leading edge shell (G4S9) 
  • sidewalls in forward nose section (G4N13)
  • swage aft cables (4x remaining)
  • stiffener for aileron control line
  • wrap every pulley with tape and heat shrink to hold stiff and straight
  • threadlock on every quick-link
  • 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)
  • prep seat mold
  • mold seat
  • mount seat
Updated buy list:
  • (1x) AN3-26A for G4T14
  • nose skid plastic plate
  • covering & adhesive
Bought list:

  • (2x) 1/8" stainless steel quick-link
  • 1" fiberglass tape
  • Seat

Sunday, April 24, 2016

Working on the to-do list


Here is the process of attaching the aileron control tube guides.





Here's what I ended up doing for the aileron turning pulley bracket.  The two-piece version didn't work well with my pullies, but this three-piece is great.  The pulley sandwiched in the middle prevents the pieces from racking.

Here is the aft tip uppers brace freshly installed.  It just barely touches the last rib, so it should be well supported.  I was thinking of lashing these together with a fiberglass tow.

Other than the pictures, I checked off a few items from the to do list:
  • DONE install bolts on aileron turning pulley
  • DONE install correct length bolts on both aileron pulley brackets
  • DONE correct bolts for horizontal tail strut lower attachments (G4T19)
  • DONE move left aileron control line to below the cross-brace cable at the root area
  • DONE attach snap hook on elevator control arm with shock cord
  • DONE install correct length bolts both aileron and flap hinges (there is an AN3-6 in place of an AN3-4)
  • DONE install correct AN3-5 bolts into cabane hinges
  • DONE bolt lengths and cotter pins on cabane to wing attachments
  • DONE cabanes don't fold nicely against bottom of wing ... turned out that I needed to move cabanes to be inside the hinges, rather than one inside, one outside.  Good to do this before match drilling the new nose carry-through tube since it'll affect the alignment.
  • DONE check if rudder pedal hinges have cotter pins ... they don't, but they'll be removed for covering and I'll have to check that every castle nut has a cotter pin.
  • DONE enlarge holes and deburr the aileron crank tube plates so the stainless part don't rub a sharp edge
  • DONE check if the control stick axis bolt has a cotter pin ... it does not, needs to be changed
  • DONE confirm there is a sleeve in the nose tube lower attachment (had to add)
  • DONE trim nose skid tube to length
  • DONE aft tip brace left wing
  • DONE glass wrap on aileron control tube guides (4x total)
  • DONE flip side of flap panel flange and bolt directions (see G4S10)
  • DONE glass the right flap ribs
  • DONE glass the left aileron ribs
  • DONE hard-points for the flap control flanges (left)
  • DONE hard-points for the flap control flanges (right)
  • DONE right wing aft tip brace
And there are just a few items left:
  • change control stick axis bolt to drilled with cotter pin
  • flip aft aileron control horn bolt to other direction
  • rivet aileron crank tube to trailing edge (G4S4)
  • round off the tail skid to be more roundy than pointy
  • new cabane aft tubes
  • cabane compression braces (some are loose after the cabane rework from G3 to G4 design)
  • AN3-26A bolt into the forward line guide bracket, replacing a rivet (G4T14)
  • aileron crank tube slot
  • make a nose skid (G4N10)
  • glass the right aileron ribs
  • glass the ribs to LE and TE
  • leading edge shell (G4S9) 
  • sidewalls in forward nose section (G4N13)
  • swage aft cables (4x remaining)
  • stiffener for aileron control line
  • wrap every pulley with tape and heat shrink to hold stiff and straight
  • threadlock on every quick-link
  • 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)
Updated buy list:
  • (1x) AN3-26A for G4T14
  • (2x) 1/8" stainless steel quick-link
  • find a better seat and then actually attach it ... I like what EC Goat did for a seat ... I also found a few go-kart seat options (thanks for the tip Jeff)
  • covering & adhesive
  • nose skid plastic plate
  • 1" fiberglass tape
  • 3M Super 77 spray adhesive

Monday, April 18, 2016

Miscellanous

Looked up emergency parachutes.  Found the Lara series at Wills Wing.  The "max pilot weight" appears to be the total weight hanging from the chute.  At ~175lb plus equipment and a 154lb Goat, that puts me outside the 250lb and to the 400lb class of Lara parachute.  20ft diameter and ~8lb for the "gold" series with a ~$1250 price tag.  https://www.willswing.com/lara/

Figured out why I bought new cabane tubes.  In shortening the aft cabane tubes, that put the new bolt hole squarely between two old rivet holes.  Yup, definitely going to replace these now.


I put in the order for the random few bolts that I'm missing.  At the same time, I took a closer look at the Aircraft Spruce seat.  It looks too wide and really short for fitting Goat.  Anybody have any great ideas or sources for seats?

The Berkeley Point Hardware site I used for the stainless steel quick links has a $30 minimum order and a $10 minimum shipping fee.  That's an awful lot for just two quick links.  Looking for an alternate vendor.

Sunday, April 17, 2016

A giant to-do list

I got a bit too much sun yesterday working in the back yard, so today was less sun and more list-making.  After taking apart Goat and putting it away, I flipped through the drawings page by page and tried to mark everything there is left to do.  Too many things... so here are a few pictures to lessen the length of the list.





Open questions:
  • Do the aileron control rods need quick links?  They were very awkward while attached to the wing during dis/assembly...
  • How to get the ailerons to fold flatter against the wing upper surface?
  • Why aren't the cabanes folding flatter against the bottom of the wing?
  • Aft, lower strut attachment bracket holes are twisted?  Re-make the nose carry-thru tube and match drill?
  • Check cabane aft tubes ... why did I buy replacements last big order?
 Buy list: 
  • small shock cord
  • 3/4" washers (3x needed) for the flap control flanges
  • 1/8" quick links (1x flap, 2x aileron linkage)
  • (4x) AN3-4 for hinges
  • (4x) AN3-5 for hinges
  • (4x) AN3-5A for aileron turn pullies
  • (2x) AN3-24A for root area
  • (2x) 3/8" x 0.035" x 20 for tip aft upper brace
  • find a better seat and then actually attach it
To Do list:
  • bolt lengths and cotter pins on cabane to wing attachments
  • install bolts on aileron turning pulley (done left, not done right)
  • install correct length bolts on both aileron pulley brackets
  • swage aft cables (4x remaining)
  • fiberglass the ribs to LE and TE
  • leading edge shell (G4S9)
  • glass wrap on aileron control tube guides (4x total)
  • correct length bolts both aileron and flap hinges (there is an AN3-6 in place of an AN3-4)
  • correct bolts for horizontal tail strut lower attachments (G4T19)
  • glass the ailerons and right flap ribs
  • hard-points for the flap control flanges
  • DONE move left aileron control line to below the cross-brace cable at the root area
  • rivet aileron crank tube to trailing edge (G4S4)
  • flip aft aileron control horn bolt to other direction
  • flip side of flap panel flange and bolt directions (see G4S10)
  • aileron crank tube slot
  • aileron crank tube plates enlarge holes and deburr so the stainless part don't rub a sharp edge
  • stiffener for aileron control line
  • trim nose skid tube to length
  • make a nose skid (G4N10)
  • check if the control stick axis bolt has a cotter pin
  • check if rudder pedal hinges have cotter pins
  • confirm there is a sleeve in the nose tube lower attachment
  • sidewalls in forward nose section (G4N13)
  • round off the tail skid to be more roundy than pointy
  • threadlock on every quick-link
  • AN3-26A bolt into the forward line guide bracket, replacing a rivet (G4T14)
  • attach snap hook on elevator control arm with shock cord
  • neoprene eyebolt spacer: horizontal stab (G4T8), elevator control arm (G4T16), tail strut (G4T19)
  • wrap every pulley with tape and heat shrink to hold stiff and straight
  • cabane compression braces (some are loose after the cabane rework from G3 to G4 design)
  • check every quick pin for elastic retainers are both present and correct length (several are just singles)
Post-covering to-do:
  • inspection panels
  • velcro to hold ailerons & flaps up for storage
  • gap seals
  • tow-hook release pin, line, guides, and handle (G4N17)
  • emergency parachute (G4N19)
  • fairings for main struts, jury struts, and tail struts

Saturday, April 16, 2016

Glorious spring!

Lots of work, and it's only Saturday with tomorrow's weather forecast to be even nicer.

First was a little pre-assembly.  Move all the sub-assemblies to the back yard, and pull the left wing down from the wall.  Had to bolt on the control surfaces and I mixed up a little epoxy to install the control line guides.  Finally replaced the marked compression strut, flipped a couple bolts, and it was ready to go.

Next was a big assembly game to put together Goat to now include the ailerons and flaps!  A neighbor (shown) wandered over and helped me get through how to handle the wing with the control surfaces on.  It's important to start with the wing on the trailing edge, rather than the leading edge, for easier installation of the nose section... other than that, it went together like normal.

With it all together, I started tying the control lines together.  It took a quarter-hour to get the ailerons centered with the stick also centered.  But then the ailerons could wiggle correctly.  It's aliiive!
video

The control linkage modifications worked great, and there are no interference issues between the strut attachment and the control arm.  Full motion stops short of the two PVC guides.

Another minor modification was to push the control horn attachment point forward by an inch.  I had apparently accidentally drilled an extra hole an inch forward of the by-the-drawings location, so I moved the aft control horn arm forward to it and that location gives (to me) better geometry for the actuation.  I'd rather have differential wherein the downward deflection is somewhere around 50-75% of the upward deflection.  With the horn in the original location, it was easily the opposite differential.  Even now, there is an awful, awful lot of downward deflection.  I need a nice angle gauge to get some numbers.  I have no qualms about the strength or stiffness, just working through pilotability details.

While everything was assembled, I reworked the jury strut lengths so it does work without buying more material.  This is the attachment for the left wing jury strut attachment at the trailing edge.  Note that the AN42B hinge bolt is not through the trailing edge tube directly, rather it is one hole forward.  This is what lets the flap fold all the way upside down on the airfoil ribs.

One of the other advantages of assembling the whole kit was to allow mounting the flap panel flange.  I'm out of large 3/4" washers, but you get the idea.  With the location confirmed correct and the holes drilled, I'm going to remove the bolts, carve out some of the foam, pack that with thickened epoxy, and re-drill.  Making a hard-point will hopefully help this area stay sturdy.


Finally, just a nice photo of today's progress.  The wing ribs are just temporarily held in place with masking tape, and it looks so much better with them in place :-)

Every hole, bolt, knot, swaged fitting, and cup of epoxy is one step closer...

Sunday, April 3, 2016

Finishing off the ailerons

Absolutely cruising!
Second aileron is a copy of the first.  On Friday evening, I grabbed the second aileron leading and trailing edges from the garage and headed to the basement.  To match the hinge angles, I bolt together the leading edges and lay both control surfaces (the old and new) on a flat table.  This way, the first angle sets the second, and can be transferred to another surface as needed.

This picture shows a whole row of ribs on the first side being bonded in, and the stiffening carbon rods are installed too.  On the left is the first aileron that I'm using to copy the hinge angle.

 After waiting overnight, here are the tips ready for more.  First step was to add the trailing edge doubler (or whatever I called it last time) out in the cold garage.  Then, I took some scrap ribs and modified them to be shorter and cut with an angle to match the trailing edge.  They were also thinned a bit toward the trailing edge to make a nice transition.

After bonding in the tip ribs and respective carbon rod stiffeners, here's the pair of ailerons curing in the basement.  It'll be a few days before I can assemble everything again, with some travel early this week and rainy weather late in the week.  The next assembly day will look at the flap linkages and the aileron control linkages.  Ah, I also have to epoxy on the control line guides in the wing before then.  Always something to do.  Fun hobby :-)

Wednesday, March 30, 2016

Wing with ribs

A friend said he was having trouble visualizing the wing without the ribs, so my work tonight was basically just grabbing the aileron from downstairs, installing the tip attachment (yay), bolting it on, and taping on the ribs.

Here's what I decided at the tip.  The TE was flattened and riveted to one side of the LE.  I added a small stub extension (?) that bridges from the TE to the opposite side of the LE.  This means the aileron is technically flat at the very end, but this seems the cleanest option for the lightest weight and least fuss.  From watching videos of others' Goats, the aileron seems to get fairly stressed in this area on landing and needs all the structure that makes sense.


Here are a few long shots down the span to show the airfoil profile a bit better.

 

And here are a couple shots looking down the control line guides.  They're still just stuck on with tape, but will be epoxied on and lashed with some glass tows to give the bond some structure.
 
 

Thanks for reading!

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