Saturday Fun

I got to spend about four hours on the Wag-a-Bond today.  I started by pulling staples from one of the #3 ribs.  I then moved on and finished a #4 (aileron) rib.  There are several aileron ribs.

Following that, I, again, tried to tackle the question of the wing root fairing attach bracket reinforcing blocks.  I spent a good deal of time studying the drawings for the wing root fairings themselves.  I then did some calculations and estimated where the attach brackets ought to go.  I am not sure what I did was the right answer.  But I had to do SOMETHING.  We will see how well I did when it is time to fasten the wing root fairings.

Here is a photo of an "aileron" rib.  The curved end will form the aileron well at the end of the wing.

Yesterday

It is fun to view the stats for this blog.  I am astonished at how many people are looking at this.  There are even six "views" from Russia!

I am slogging along doing wing ribs.  I find it quite relaxing and haven't gotten bored yet.  There seem to be enough little challenges to prevent that.  Just to prove that this is me doing the work, here is a photo taken by my wife, Carolyn:

As you can see, I working from a single car garage.  I predicted it would be a challenge, and I have not been proven wrong.  When a major assembly is complete, and I am currently counting wing ribs as major assemblies, it is moved to the hangar.  At the point where I need to build the large fabrication table, the two table saws, and maybe the radial arm saw, will be moved to the hangar.  That will create just enough room for the full size (4' X 14') fabrication table.  The table itself will be built in modules.  I will detail that plan in a later post.  For now, I am a long way from building that table.

I have completed both the left and right #2 ribs, and the left and right #1 ribs are almost complete.  The only thing that needs to be added to them are the reinforcing blocks for the wing root fairing attach brackets.  Those blocks have been cause for a lot of fussing for so small a part.  The Wag-Aero plans call for 10 blocks.  They don't say whether that is 10 blocks total or 10 for each rib. A sketch on the plans seem to indicate 10 total.  Also, the rib plan shows one block near the middle of the top capstrip, which does not jibe with the drawings and details for the top wing root fairing. 

What I have found from looking at a couple of Piper built aircraft is that there is one bracket on the top of the rib just aft of the main spar, a bracket on the bottom of the rib just forward of the main spar (which will not require a reinforcing block because the nose block is there) and nine brackets spaced more or less evenly aft of the main spar along the bottom of the rib.  Which, according to my old fashion math, totals 10 reinforcing blocks, mostly along the bottom of the rib, for each wing.

The bracket itself is a study in confusion.  The Wag-Aero drawings show a simple aluminum bracket to be attached to the rib by wood screws.  It appears that the intention is for the wing root fairing to be secured to the bracket with sheet metal screws. 

Piper seems to have been somewhat confused, as well.  There are two drawings in the set for the PA-15 for the wing root fairing attach bracket.  One is number 11455 and the other 11463.  They were created within a few days of each other in 1947.  11463 was drawn by LEK on 9/30 and checked by JCB on 10/3.  11455 was drawn by RJC on 9/29 and checked by LEK on 10/6.  Further piquing my curiosity is the fact that 11463 is drawn incorrectly, with the long leg only 1-3/8" instead of the specified 1-1/2". They both show revisions, though not the same revisions, up to 1957, when the revisions for 11463 cease.  The revisions for 11455 continue to 1963.  The big difference between the two is that 11455 shows a rivnut to receive the fairing attach screw.  Much preferable to a sheet metal screw as the lower wing root fairing will need to be removed for each annual inspection.  It appears that the rivnut was added in 1950.  My guess, as a response to reports of stripped out sheet metal screws.

Plating the #1 ribs resulted in some education.  Plating the first one was relatively easy.  I simply built a full rib, removed it from the jig after gluing up the gussets, flipped it over and attached the plating.  The second rib was much more of an adventure.  I won't detail the process (because I won't do it that way again), but it was a scramble.  During the scramble I needed to fasten down part of the plate RIGHT NOW or have a problem.  I grabbed the nearest staple gun (I have three and have been using them as weights) and plugged in a couple of staples.  This particular gun had heavier duty staples than the gun I had attempted to use before.  All the literature recommends using regular weight (like you would use in your office stapler) staples and that didn't work well for me.  The heavier staples worked great.

So I have abandoned using the big bolts as gluing weights and have returned to staples. 

Today I intend to pull the staples from the first #3 rib, which is complete except for that step, and glue up the gussets on my first aileron rib (#4).  When those are done and moved off the jig and up to the hangar, I will work on the wing root fairing attach bracket reinforcing blocks.

Dawn Patrol

No progress on the Traveler today...but a great flight out to Hoquiam and back.

Clamps

You just can't have too many clamps.

The #1 rib on each wing, which is the most inboard rib, is "plated" with 1/16" plywood on the inboard side. 

Step by Step

For the next few weeks it is going to be difficult to find interesting things to talk about.  I have 22 ribs to build, and it will be pretty repetitive.  But I will try. 

The first photo here shows one of my joints.  I decided I needed to take a photo or two of these joints.  They all end up getting covered by gussets.  I know they are there, but nobody else ever will. I am contemplating building a "show" rib.  The ribs really are pretty, and one particularly built as a wall hanging seems like a good idea. 

Building these ribs is really relaxing.  It requires slow and patient work.  My usual procedure is to mark the piece and make a preliminary cut just to the "waste" side of the pencil mark.  This always ends up with a part a touch too long.  I use the disk/belt sander to sand off about 1/2 of the pencil line and then re-check the fit.  If still too long, I sand until the pencil line just disappears.  If still too long, I make a new pencil line and repeat the procedure.  It is kind of a fussy method, but it helps from taking off too much material. 

The next photo is an overall photo of the wing rib jig with a partially completed rib.  I cut and fit all the capstrip before I start gluing and installing gussets.  Just the way I do it.  Do any of you from Wagbuilders Group glue things up as you go?

The bits of business card provide clearance for the spars.  One needs about .010" to .015" clearance to make sure the rib can be slid onto the spar.  The business cards mic out at .013".

You can also see the syringe I use to apply glue and the small table saw I use to make rough cuts.  I use the bastard cut file instead of sandpaper to clean up fuzzies and make small adjustments. 

First Wing Rib

This is the first wing rib.  Pretty exciting.

Having produced something that looks aviation related, after cutting a million small, nondescript parts, I feel like I am really building an airplane.

This first rib went together pretty much as expected. I had originally thought I would hold the gussets in place while the glue dried with staples.  That did not work out well.  Probably because I used birch plywood for my gussets instead of the more usual mahogany.  The birch is much harder. 

I noticed, wandering the Photos section of the Wagbuilders Yahoo Group, somebody used large bolts placed head down on the gussets as weights.  I happened to have a bag full of big bolts (no recollection of where they came from), so gave that method a try.  It worked fine in the test runs, so that is the method I used in building this rib. I am pretty sure I will continue this method through the rest of the ribs.

Building the ribs is a fussy job.  Some of the EAA information recommends just cutting all the capstrip square and butting it up, counting on the gussets to make the full joint.  The plans I am working from show each piece mitered into the adjoining pieces.  Mine are all mitered in.  It takes some time to get each piece just right, but I am proud of the result, even though you can't see it.

I had originally planned to do most of the fine cutting with an Exacto razor saw.  But I found the grain in the spruce to be too open when trying to crosscut.  So I unearthed a small table saw (Harbor Freight) that I use in my model building for the rough cuts and do the final trimming with the disk sander. One of the EAA tips is to make a single pencil line where something needs trimming and then just sand the pencil line off, no more.  Works great.

There is also some final trimming of some of the gussets, primarily around the spar openings, that needed to be done.  That trimming was done on the band saw.

So far I am very pleased with the Titebond III glue.  My test joints passed the "break test" with flying colors.  The glue joints are way stronger than the wood.  One nice attribute is the quick and firm inital grab.  Titebond does not tout this feature, but the initial grip is pretty firm.  The glue also dries to handling strength in about 30 minutes.  I wouldn't put a lot of strain on a 30-minute joint, but it will allow me to flip the rib over and go to work on the obverse side gussets in a reasonable time.  I apply the glue with a glue syringe, available from MicroMark.  The syringe gives much better control over the amount of glue applied than trying to squirt it from the bottle.

I should be able to complete one rib in an evening and two, maybe even three, when I have full Saturdays available.  Today is a slow day because I am not feeling well.

I am labeling each rib and marking them off on the plans to be sure I get everything done and to help me keep track of what I am doing and what needs my attention next.  Completed ribs will be stored in my hangar.  One of the challenges of a project this large in a single car garage is storage space, or, rather, the lack thereof.  This rib is marked "R2", meaning the #2 rib in the right wing.

Why did I start with the #2 rib?  Because the #2 is really the only "typical" rib (I know, that sounds strange).  The #1 rib is plated on the inboard side with 1/16" ply for its entire length.  The #3 rib is plated on the outboard side from the trailing edge to the rear spar.  Ribs #4-#9 are "aileron ribs, meaning they end at the aileron well.  Rib #10 is plated on the inboard side from the trailing edge to the rear spar.  Rib #11 is the "Tip Rib" and is slightly different than all the others. I will need to modify my jig to do the two (left and right) tip ribs.

I like wing ribs.  They are pretty (particularly in wood, aluminum not so much) and are an interesting study in basic structural engineering.

I think Holly would be proud.

Arlington

I ran into this beautifully restored Vagabond at Arlington.  The attention to detail is amazing.  I fell in love!  Incidentally, that is the kind of mag switch I want for my Wag-a-Bond.  I will let you soak in these images.  I spent a lot of time just looking at this aircraft.