Tail art

My Goat has been branded:

Starting up Painting again

As part of clearing the inspection items from the list, I've started painting the surfaces that are already finished.  This includes the vertical tail, the horizontal, and the nose section so far.  The elevator is queued up next, and the wing surfaces should follow shortly thereafter.  I'm doing this out of order to clear those structures from the garage to work on the wings.

Painting has been three cross-coats of Glidden Gripper latex interior/exterior white primer thinned 30% with water and applied with a small foam brush.  The first coat tends to use the most paint, mostly because the paint is half disappearing through the fabric to wet out the backside.  Subsequent coats definitely spread out better.

On the rudder I painted previously, the three cross-coats were followed up with three sprayed cross coats.  This ended up making beautiful coverage, but at the expense of a lot of weight.  I suspect the sprayed coats were much thicker than they needed to be.  I'm going to stick with hand brushing this time to better control the weight growth.

 Inspection rings on the tail covering and ready for paint:

Aaaand, after painting:

Inspection!

Thank you to Steve for coming over to give a pre-covering (well, pre-wing-covering) inspection.  In short, my Goat passed with only one must-fix item - an aileron control line ran over a cable and rubbed when it should have gone under and cleared.  I also have a few pages of minor fixes and inspection points...

In case it matters to readers, Steve is an A&P, has built multiple homebuilt aircraft (including one named Hot Grand Champion at Sun 'n Fun), is a multi-time national champion flying pattern RC aircraft, worked on jets as a service member, and has made a career in aviation.  He's qualified.

We did an assembly of Goat together, walking through the process and looking at each joint when inserting the pin.  (recently I adjusted the length of the jury struts, so it actually went together nicely)  He then walked around slowly and looked at practically every joint and connection and cable.  Steve found many small things, like a missing washer or bolts that were too short.  He also looked at the big picture, such as noticing a slight bow in the leading edge tube.  This was really thorough!

Here's the full list:

• DONE right forward aileron cable goes under, not over --- SAFETY CONCERN
• DONE switch one washer over to the bolt head in the rudder pedals
• DONE left wing trailing edge cable is not tight
• DONE flip upper bolts behind seat
• DONE trailing edge root bolts are short, and don't match the right side
• DONE turn around cabane aft upper bolts
• DONE neoprene spacer G4T8
• DONE neoprene spacer G4T16
• DONE neoprene spacer G4T19 (2x)
• DONE lower tail flying wire needs to be bent a little more out, in line with the cable
• DONE put kink in elevator covering stiffener (worked like a charm!)
• DONE tail flying wires chafe the flap bolt head - twist bolt so the cable doesn't rub
• DONE radius tube on the end of aileron torque tube, because it can rub the nose covering
• REMOVED elevator cotter pins were wrong method of folding
• DONE add reinforcement patch/tape where elevator control bolt rubs fabric (inside tail)
• DONE (5x) add reinforcement patch on horizontal stabilizer bolt heads
• DONE add inspection ring for the elevator linkage
• DONE add reinforcement patch inside the nose covering that could get rubbed by the ailerons
• DONE mark nuts with torque seal
• DONE add friction tape (cloth, not plastic) to cable crossings that rub
• DONE G4N7 - AN3-26 drilled for the torque tube in pitch direction
• SKIPPED G4N11 - AN3-14 drilled for torque tube in roll -- added torque seal instead
• DONE put liquid electrical tape on the control cable ends where I forgot heat-shrink
• DONE G4S13 - aileron line stiffener (1/4" x 0.035" x 10" tube)
• install leather patch guides for elevator control lines
• replace the nose tube (because the holes are twisted)

Items to do as part of the wing covering

• DONE make foam pads for the lower surface wing ribs to support the fabric
• DONE add/check all cotter pins
• SKIPPED trailing edge AN42B hits fabric (where?) -- shorten?
• DONE add inspection ring for the aileron linkages
• DONE add inspection ring for the aileron pullies
• DONE make sheet metal stiffener for the aileron linkage
• add leather patch to wing tips where will rub the ground

List that includes buying things:

• BOUGHT add friction tape (cloth, not plastic) for cable crossings
• BOUGHT put liquid electrical tape on the control cable ends where I forgot heat-shrink
• BOUGHT replace the nose tube because the holes are twisted
• BOUGHT use torque seal to mark bolts
• BOUGHT leather patch for elevator cable on the covering
• BOUGHT leather patch for wing tip where it will rub the dirt
• BOUGHT G4N7 - AN3-26 drilled for the torque tube in pitch direction
• BOUGHT G4N11 - AN3-14 drilled for torque tube in roll
• BOUGHT G4S13 - aileron line stiffener (1/4" x 0.035" x 10" tube) 
• BOUGHT find/make draw-string baggie for protecting the control cables during transport (2x)
• SKIPPING possible treadless tire option (to save weight)

Assembly Inspection and Annual Inspection

• left wing aileron line needs to go below the cable (must catch during assembly)
• metal-to-metal contact at each quick-link in the elevator control (in the nose), in the aileron control (in the wings)
• use tri-lube (or other recommended) to lubricate the Harken pullies

Since Goat was fully assembled, here's a nice shot of the current progress.  Looks much nicer with both ailerons covered, and the covered cabanes add some visual solidity.  It'll soon be really different with the wing panels covered too!

Here is the offending safety issue.  You are looking at the right wing, toward the leading edge from behind, and looking at the aileron pulley sending a control line toward the root.  The rope going over the steel structural cable is the issue, since the cable would eventually saw through the rope.

The to-do list

Digging up the old to-do list from 2016, what else is accomplished that wasn't done back then, and what else is on the list?

Nose:

• DONE make a nose skid (G4N10)
• change control stick axis bolt to drilled with cotter pin (will have to remove the torque tube)
• sidewalls in forward nose section (G4N13)

Tail:

• DONE replace lower horizontal strut to tail connection bolt with a longer one
• DONE check all bolts are appropriate grip lengths 
• DONE LATER find/make draw-string baggie for protecting the control cables during transport

Wing:

• DONE glass the ribs to LE and TE
• DONE leading edge shell (G4S9)
• stiffener for aileron control line
• DONE 2019 foam blocks on the lower wing surface for covering support at the compression struts?  I think Yando Goat did this.

Miscellaneous:

• DONE wrap every pulley with tape and heat shrink to hold stiff and straight
• DONE check every quick pin for elastic retainers are both present and correct length (several are just singles)
• threadlock on every quick-link 
• DONE 2019 covering reinforcement patches
• DONE 2019 painting
• DONE LATER mount the airspeed sensor to the forward nose tube

Buy list:

• DONE covering and adhesive
• DONE (1x) 1/8" SS quick-link
• radio (walkie-talkies of some variety) 
• tow line

Other:

• reassemble the trailer
• extend the trailer tongue
• make a platform/box for the trailer to carry Goat
• set up a car for towing (hitch + wiring)
• DONE 2021 tags for the trailer (inspection??)
• DONE 2021 sort out a car towing arrangement
• find a place to fly

Uhg.

Odd jobs

Now I'm checking off odd jobs again.  Small stuff takes random amounts of time and comes with little rewards that add up to satisfaction that it's almost ready.

I finished covering the right aileron yesterday.  Man, covering takes time, working over every square inch of the edges and especially around places with high curvature.  Here is the aileron (and cabanes) covered.

Last assembly, I noticed that the aileron lines from both left and right attached with hooks to the control system in the fuselage.  Without being genderized, there is the possibility of assembling the ailerons reversed.  Whereas I want to claim I'm smart enough to not have that happen, there is no reason to gamble on myself.  I added a quick link and snap hook to one side of the linkage, and added a corresponding welded steel ring to the other end of the line.  This way, it literally won't hook up incorrectly.  This was per the drawings, for what it's worth.

Also related to the aileron hookup, the control rods are supposed to mounted permanently to the wing per the drawings.  I found they would flop around during assembly and got in the way, or jammed up.  Instead, I made an extra set of quick pins.  These pieces will be mounted after assembly.  They'll also be easy to get lost, since they're loose items.  Perhaps someone can recommend a better idea?

Lastly, I added a reinforcement patch to the vertical tail section to (finally) install the horizontal retention clip bungee.  This location also is convenient to hold the tail struts during transport.  After some trial and error, I discovered the flying wires can be clipped into the micro clips to keep them from flopping around as much during transportation.  These always bugged me, so it's wonderful to have a keeper.

I'm staring at covering the wings as the next real work task.

Covering the cabanes

I thought it was worth while remembering how to cover by starting on something with little aerodynamic risk ... the cabanes were the ticket, as opposed to the remaining aileron or the wings themselves.

I'm using the Stewart Systems process, which starts with cleaning all the surfaces with alcohol, using cloth tape to cover any sharp edges or corners (like the bolt heads), and then applying a layer of glue to dry.

This is one of the cabanes after cleaning and after edge taping.

From my old material cut-list, instead of using a single piece of material over the whole cabane, which would leave a lot of wasted material, I decided to cover the front and back triangles separately.  Practically, this meant a weird seam at the junction of the fore and aft triangles, but I'm okay with that since these pieces are structural but not really aerodynamic.

Here's the back triangle covered, mid-trimming of material from the second side overlapping onto the second.

Finally, the forward triangles were covered in just the same way, with an overlapping seam to join to the back half.  This covering job took place basically all day on July 4th, so it wasn't really that terrible amount of work.  There is definitely some time spent waiting for the adhesive to dry, but most time is spent pulling out wrinkles around corners or areas with bolts.  Here are the final products.

I will say, I got better even on the second cabane after completing the first.  It also was WAY cleaner to let the adhesive dry completely, rather than trying to use a heat iron into wet glue.

Onward to finish covering the aileron, which is the last small part, leaving just the two wing panels remaining (and probably three dozen reinforcement patches on all of the smaller parts).