10 February 2014

Empennage: Rudder. Trailing edge riveted.

The trailing edge on the rudder has been riveted.  To mitigate a curved edge, I picked up some angle iron


The edge turned out fair.  It's reasonably straight but since we alternated the rivet orientation to give the rudder a cleaner appearance, there is a minor waviness to it.  In fact, it's the skins that are wavy.  The trailing edge wedge seems fine.  Might be due to excessive pressure from the riveting gun.  We did have to turn it up to drive the rivets properly.  My guess is the angle iron flexed too much.  Perhaps it should have been thicker.  Oh well, you get the airplane you build, not the one you want!


Might be able to work those out using the technique outlined in Section 5.


Empennage: Aft fuselage. Bottom skin, bulkheads, stiffeners and bellcrank ribs riveted.

This was a fun and quick exercise.  Easily accessible rivets.  We used "Mr. T" to buck these guys.  Three quick bursts hit them all.  Curious about my sawhorses?  Look here.






And that's as far as I can go with this part as there is no more space in my house.  If I put on the longerons, this plane will only do some very tight pattern work in my basement.  If/when I fully complete my wings (have a small punch list to work through), I could squeeze the full aft fuselage in my living room.  We'll see if I'm willing to have that additional "roommate" later.

09 February 2014

Empennage: Elevators. Left elevator foam ribs sealed in.

Foam ribs sealed in.  My first time working with sealant without making a mess!  The approach was to slip the ribs in, apply sealant to the skins and spar, then slide the ribs over.  Much easier than shoving the ribs in after sealant was applied.

Trim tab rib.  Upper surface sealant slathered on.  Lower surface still dry.


Elevator rib.  Sealant applied to skins and spar.  I went ahead and applied sealant for the trailing edge too since I had already mixed up a batch.  Will make things look nicer and possibly mitigate corrosion?


Parts weighted and clamped for sealant curing (we're building the saw horses for the start of the aft empennage).

Empennage: Vertical stabilizer. Complete.

Always nice to be able to say "complete".  Riveting was straight-forward.


The fact that I riveted the rear spar prior to placing the skin was, as I figured, not an issue for accessing the rivets along the middle rib.


Tada!



EAA Technical Counselor visit

I had a visit from my tech counselor today.  Wanted to consult with him regarding the issue with my horizontal stabilizer aft spar not lining up with the skins and ribs.  He thought that applying pressure to various parts of the stab might get the holes to line up and if the aft rib flanges didn't line up, to just drill them out.  He said this was a problem he'd seen many times on pre-punched kits.

The outcome and a detailed description of the issue can be found here.

Empennage: Rudder. Stiffeners, ribs, spar and horn riveted.

To get the stiffeners riveted on the rudder, you do a sort of "reverse peel", starting at the bottom and working your way to the top, pulling each aft stiffener rivet.  Then you pull the forward pair of stiffener rivets.  With the stiffeners locked together, it's a more solid feeling rudder than other models.


A few shots of how the pull rivets look.  Aft end.


Forward end.


Be careful to avoid this unfortunate problem.  Sand this to fit around around the horn's protrusion so it seats nicely before riveting.


At first we tried to buck the horn brace rivets with a tiny bucking bar stuffed inside.  After messing up the first rivet and drilling it out, thinking it was time for pop rivets, it donned on me that we could squeeze them with my longeron yoke.  Duh.  No problem.


Not shown in the above picture is the bottom, forward-most AN426AD3-4 rivet that holds the skin to the horn brace (in the above image, it would be the lowest cleco'd hole).  We could not fully squeeze it with any of the yokes I have.  Didn't seem feasible to buck it.  We left it about halfway squeezed.  I'm okay with leaving it as-is, but I'll put it on my squawk list so I can remember to keep it in my mind should I later find a way to do it or meet someone who has.

Here the rudder sits waiting for the trailing edge to be riveted.


Empennage: Horizontal stabilizer. Ribs and front spar riveted.

The horizontal stabilizer is at the point where only the rear spar needs to be attached.  That won't happen yet.  There is a gross misalignment that I will elaborate on more when the fix is determined.  Until then, here's where things are at.  Update:  See here for misalignment details.

Nose ribs went in without a hitch.


Looks clean inside with the ribs and stringers.


Full stab without aft spar riveted in.


08 February 2014

Empennage: Elevators. Rear and front spar riveting.

With one only skin on, the elevator rear spars are simple to rivet.  The tungsten bucking bar (henceforth, "Mr. T", so dubbed by my RV-9A friend who lent me much help over four days).


The elevator rear spars, in the area absent the trim tab, are recessed behind a good 5.5 inches or so of skin.  Always preferring squeezing to bucking, especially on control surfaces, I tried to get a super deep yoke, and after grinding away a notch to fit the spar, the yoke turned out not to fit my squeezer without grinding some of the bottom fork.  Can't return that!  So, I went with the special bucking bar suggested in the plans.


I used my steel plate to provide a rigid counterpoise against the lever arm, after shimming the elevator up.


A flashlight illuminates the contact point between the shop end and bucking bar since the bar will rotate around the fulcrum between it and the steel counterpoise during the violence of the bucking process.  We managed this movement by hitting the rivet in 3 short, consecutive bursts, separated by enough time for me to yell "stop" if the bucking bar had slipped excessively.  Right elevator shown below.


The left forward spar was easily riveted with the squeezer.  Left elevator shown below.  Skin is tight with the second-from-inboard lower sector having some oil-canning.  I can reach in through the forward spar lightening holes to seal in a light stiffener.  Shame, but not a big deal.


Right elevator isn't shown at the same state as above because I messed up two rivets holding the tip rib to the forward spar.  When we drilled them out, it became a mess because access was, well, impossible.  We managed to set the replacement rivets after upsizing one to an AD5 (from an AD4) but I didn't like how it looked.  My tech counselor was okay with it, but in the end I decided I didn't want it in the plane, so I will be redoing the right front spar.  I have a lot of scrap metal from this project!

Empennage: Elevators. Trim tab reinforcement doubler and gusset riveted.

The trim tab reinforcement doubler is attached to the front spar with AN470AD3-3.5 rivets.  


These are 1) hard to access and 2) round headed.  I don't have a rivet set for AN470AD3 size rivets.  I do have a squeezer set but I didn't have a bucking bar to mount it in.  We tried the below, but it wasn't deep enough to clear the skin over hang.


So we just bucked it with my narrow flush set which is acceptable (see 3.3.3.2).


Wasn't too bad to get in there.  Just took some planning and care.


Here's what the shop end looks like on the most difficult trim tab reinforcement doubler rivet.  Pretty good actually.  You can see we scuffed the one pop rivet there, but that's not an issue.  We did have to drill the original rivet we placed here since the bucking bar slipped against the nutplate and destroyed the shop head.


Squeezing the gusset rivets isn't easy.  Had to upsize one to an AD4.


We had to drill out the three upper inboard rivets holding the skin to the rear spar and piano hinge since I mistakenly closed things up before riveting the gusset to the rear spar. Not a problem and those rivets were easy to hit.


Next up is sealing in the foam ribs, closing out the lateral tabs and bending the forward skins shut.

07 February 2014

Empennage: Elevators. Trim tab trailing edge riveted.

Elevator trim tab trailing edge is riveted.  Because these trailing edges are much thicker than those of the wedges used in the other flight control surfaces, it's much easier to preserve the straightness of the edge.


You can see the 3M F9460PC VHB™ Adhesive Transfer Tape sticking through.  In the future, I would use sealant for 1) a nicer look and 2) some semblance of corrosion protection.  In fact, I ended up using it on the left elevator only because I had already mixed it for the foam ribs.

03 February 2014

Wings: Fuel tanks redo. Delivery.

Because I'm redoing my fuel tanks, I'm really only posting progress reports rather than additional details.  See here for why I'm redoing my tanks.  Technique details on the original fuel tanks are found in their associated posts.
60x23x8 inches at 80 pounds.  The contents of this wonderful box represent an extraordinary piece of mind.



An ingenious methodology to the securing of sealant for shipping.


They cut the 60" J-stiffeners to fit in the 60" exterior length box.  Inside length of the box is 59" and the required length of the stiffeners for the tanks is 54".  Unfortunately, they cut the stiffeners to 52" (with shears no less, so the edges are warped).  Initially I thought I could just overlap two stiffeners to make up the 54" length, as is done in the wings, but then thought it would just be an invitation for later potential leakage.  I will discuss with Van's to see if they'd be amenable to replacement.

Shop: Bought a Semco sealant gun.

When I sealed my original fuel tanks (see here for why I'm redoing them), I used a $77 manual syringe gun (it's much cheaper on eBay, should have checked there first!).  It made things much easier than using Popsicle sticks and cotton swab stems.  However, it was hard on the forearm muscles and would continue to dispense after releasing the trigger.  Also, the 1 ounce syringes weren't realistically reusable, though at $0.62 each, that wasn't too much of an issue.


Turns out, one can find used Semco guns on eBay for much less than I bought my syringe gun for.  So, I picked up a used Semco model 250-A sealant gun for $30.  When done, I can probably turn around and sell this for what would essentially be a wash.


Mine comes with a 2.5 ounce container which is more than what I had with my syringe gun, so I'm thinking that I could buy a few 2.5 ounce cartridges and nozzles, fill them up with sealant as needed through the day and use them.  The next day I can easily pull the partially cured sealant out of the cartridges and reuse them.  I did something similar with the syringe gun to clean it.  Sealant does not stick to smooth plastic very well so it just peels off.

Stay tuned to this post to find out if Techon cartridges, plungers and nozzles work.  They're much cheaper than Semco's and look like they're the same shape.  Update 12-May-14:  I have verified that these do work with this gun.  Update 17-May-14:  And this elbow makes getting into crevices a breeze.