Sunday, August 30, 2015

25-06 #1 install rear window (dry)

Well, my plan had been to finish up the cables, bulkhead and fuel tank before installing the window, but I’m being flexible.  Removing the fuel tank wasn’t too bad since it was (1) already empty and (2) not connected.   I think installing the rear window with the tank in place would have been a bad idea, so perhaps this is all for the better.

On the other hand, I discovered that I had done something correctly, but then “fixed it” a few weeks ago.  Specifically, I was surprised to find that I had “missed” two rivets at the top of the roll bar splice plate.  Being the industrious overachiever that I am, I promptly filled in those holes with CS4-4’s.  Today, I re-discovered that those holes were on purpose, and were to be used to help screw down the rear window.  My bad.  The rivets were drilled out #30 and tapped 8-32 (vice 6-32).  The corresponding holes in the window were opened up to 3/32” with a step drill (hand twisted) and the hardware was exchanged to #8 screws and washers.

Nicolai helped me wrestle the window in place and set every 3rd screw to hold it there.  I’ve taped up the edges and masked off the areas likely to get contaminated with goo when I squeeze in the Pro Seal.  (In case you are wondering, I trimmed off the edges of the white covering before I did the installation.  I didn’t trap the covering inside the assembly.)   Tonight is the first of 5 consecutive nights at work, so I may not get to the next step until next week.


IMG 4628

rear window ready for Pro Seal

stabilator cable problems

Well, i’ve had a hell of a time with the stabilator cables, and this is just a status report.  (in other words, not solved yet.)

long story short:, I think the cables are too short.  Posting to VAF resulted in several good suggestions.  Key among them was the observation from an EAA Tech Counselor that I had problems with running the cables in the correct holes last month, and he recommended that I double/triple check that the routing is correct. Unfortunately, I believe that it is.

When both cables are tightened to 45 # (max, per The Book) the top set shows 5 threads (not 3) and the bottom set shows 8 threads.  The threads are 24/in pitch, so the top cable is 4/24” =  0.167” too short and the lower on is 10/24 = 0.417” too short. 

I spent hours (2 or 3) try to ensure that I was looking at the correct cable and not get confused with the running.  I eventually did the following:  the rudder cable was disconnected from the tail region and brought forward so that the protective sleeve was clearly visible.  This served as positive ID of the rudder cable.  BTW, the rudder cable runs from the lowest to the highest hole as it moves aft.  (Just thought you’d want to know.)     Next I detached the upper/right cable from the turnbuckle and pulled it all the way back to the pulley.  I put a metal rod (from surplus piano hinge) through the resulting empty hole to identify it as hole/cable associated with the upper stabilator horn.


IMG 4627

removed upper stabilator cable, lower stabilator cable, rudder cable.


I put the seat ramp back on and reconnected the cables, but they were still too short.  Damn.    If I tighten them up to the specification of “not more than 3 threads showing” I get a tension that is off the scale and results in much too much resistance in pitch.

The reason I’m not really buying the ‘cables are too short, return them for a longer set’ is that it’s both sets of cables.  That certainly suggests that there’s a common (systemic) cause that I’m not seeing.   

I’m also not too interested in replacing the ones in the plane, simply because of the labor involved.  I’d rather use a longer turnbuckle which, conveniently,  happens to exist.  Specifically, the MS21251-B5L turnbuckle is 4.00 in long while the MS21251-B5S (supplied) is 2.25 in.  I think the extra length will address the problem nicely, and without the labor of changing out the cables.  A VAF commentator opined that I may run out of ability to later tighten them when the cables stretch with time, but I don’t think that will be a problem if the -B5L’s are threaded all the way to the midpoint as are the current -B5S’s.

I’m going to call Van’s on Monday and see if they have any other places to look for the mysterious length anomaly and either get their blessing for using the -B5L’s or get them to exchange my current cables for new (presumed longer) ones.  

More To Follow...

Wednesday, August 26, 2015

Misc update

It’s been a long time since I last posted, but not because I’m not busy with the plane.  It’s just that I’m not completing any pages so there’s no formal report to post.

I spent a lot of mental effort reviewing all of my options for transporting the plane from my garage to the airport.  The big decision point was whether to leave the tail feathers off and transport it that way, or finish up assembly and take with with the tail feathers attached.  My concern is the wind loads of large trucks passing by and having the stabilizers to push against.  I finally decided on doing the installation at home and trailering everything in situ.  

Rationale:  There are quite a few pictures of trailered RV-12’s with everything except the wings and no horror stories to go with them.  There are several trailering rigs that even have the plane being positioned tail first, in what seems to me to be an aerodynamically unstable arrangement, yet still no horror stories.  I have selected a route that only exposes me to high speed large trucks for 2 miles (out of a total of 20 miles).  I will secure the airframe to the trailer with a large pair of pseudo-spars that will protrude from the fuselage far enough to be lift handles / tie downs. 

The side-to-side wind loads are my biggest concern for trailering and then I had the collision of two thoughts that left me with a satisfied conclusion: I can put on the horizontal stab (and get lots of other things finished that are dependent upon that step) and leave the vertical stab/rudder off since there are no other steps that are dependent upon that.  This lets me get the majority of work done at home and not have to worry as much about the side-to-side wind loads during transit.   All in all, I believe it will be safe to trailer the completed aircraft. To quote an old TV show, “I love it when a plan comes together."

That cleared up a great big mental road block that left me hunting for ’things to do while the plane is not completely assembled.’   The example that comes to mind was getting ready to place the upholstery, then realizing that the rear bulkhead isn’t installed, thus I can’t fit that portion, etc., etc., etc.  OK.  Deciding to completely assemble the plane at home allowed me to get back to work with enthusiasm.  

Done since last posting

  • Fiber glass skirt laid down, trimmed and rough sanded to functional (but not esthetic) status.  It’s now on the back burner since I have reached the point where I know I can finish it on my own.
  • Horizontal stab final attach (e.g., with cotter pins)  (Includes counter weight, trim motor, etc.)
In Progress
  • horizontal stab cables final tightening

To Do at home

  • remove gas tank
  • install Rear bulkhead
  • final install gas tank
  • final install filler neck
  • final install rear window
  • re-install ELT
  • install fire extinguisher
  • final install foreward rudder cables
  • install upholstery
  • trim flaperons to eliminate interference with fuselage
  • final fill/sand of canopy skirt
  • install canopy

To Do at airport

  • move on Sept 22nd
  • attach vertical stabilizer
  • final attach rudder
  • final attach rudder cables
  • fill with gas
  • Product Acceptance Checklist
  • Airworthiness Inspection!!!
  • install access hole covers, cowling, fairings
  • FLY!

Tuesday, August 11, 2015

Hanger C-1 at Delaware Muni Airport (KDLZ)

I spent 4 or 5 hours sanding the fairing, and have nothing to show for it as far as progress in The Book.  On the other hand, I’ve been renting hanger C-1 since July 1st, but today was the first day that I actually spent any time out there.  I took Nick shooting and we ‘detoured’ by the hanger as his way of earning the rental of an AR-15 (he likes the high powered rifles.)

We swept years of dust & junk and spider webs.  I picked up some ‘cheap’ shop lights ($200!) to hang because I know I’m going to do lots more work on 012 while she’s living here.  Spent about 30 min on a 16’ ladder hanging the lights.  Power is hard to come by—just a single outlet at the far inside corner.  I briefly though about tapping into the light bulb but that’s too high even for the ladder to reach, so I’ll just use the extension cords.

Note also the ‘scare owl’ hanging just to the left of the vertical support.  There was a lot of bird poop around that area so I got the owl to keep the nesting down to a minimum.  


IMG 4562Hanger C-1, awaiting occupancy

Saturday, August 8, 2015

34-14 glassing canopy fairing

Well, I’ve been dreading this page for a year or two, and I’m still pretty keyed up about it.  Recall that long, long ago I came across the fact that Viking Aircraft produced a pre-molded aircraft skirt that eliminated the angst associated with this step.  I purchased it and it’s in my garage but I recently (few months ago) realized that it was not allowed since I was planning on certifying ‘012 as an E-LSA.  

(A thought just jumped into my head.  More recent reviews on the Viking Shield commented that it was flimsy and prone to wind noise.  My version (see below) is ugly and may not be  long enough to cover the lower edge of the canopy supports but it is probably very stiff (lots of epoxy).  I may investigate getting my certificate, flying off the 5 hours, then bonding the nice smooth Viking shield over mine.   Hmmm. Food for thought.)

Anyway,  this is the ‘before’ picture showing the smoothed foam, and scuffed up aluminum skirt and leading edge of the canopy.  BTW, it really felt weird to deliberately scratch & scuff that expensive plexiglass!

IMG 4555

Just prior to glassing


The canopy is still mostly wrapped in its original sticky plastic.  The blue painter’s tape covers the area between the double layer of electrical tape and the plastic.  The ‘grey’ region in front of the black tape is actually dulled canopy.  The black electrical tape is the 2nd layer, as called out by The Book.  Since the instructions say to sand through the 2nd layer to achieve a nice feathered edge, I placed red electrical tape as the 1st layer so I’ll easily be able to tell when i’m making the transition.

The foam blocks are very fragile where they are tapered out around the bolt holes.  Ask me how I know  :-(     I used some expoxy/flox to glue the remnants back into place so there wouldn’t be a big void right there on the leading edge where wind loads will probably be pretty high.  I think I may inject some epoxy/flox into the back side of that area when I get the canopy off for trimming.


IMG 4556

Right Side after glassing

IMG 4557

Left Side after glassing

This was far and away one of the more stressful days of the project.   Cutting the fiberglass wasn’t too bad, but the long narrow strips (next page) were very challenging when they were very narrow.  I think I may have made a mistake by cutting the long strips parallel to the weave of the cloth; perhaps cutting them on the diagonal would have worked better.

The dry fitting of the 1st ply nearly panicked me into thinking I had made some major mistake in cutting.  It didn’t look like the intended shape at all.  I was eventually able to stretch it into something that resembled an intended shape and proceeded.  I wasn’t able to get the ‘tails’ to extend as far as I thought they should.  As I type this, I realize that I was trying to maximize the fore-aft direction of the plies and this probably resulted in shrinkage of the up-down dimension. It’s not too bad here on the left, but the plies are definitely too short on the right.  I’m going to have to work on a remedy for that.  Later.