Even More Ribs

Rib construction continues. 

This is what the stack looks like at the moment..

One question that pops up from time-to-time is the cost of the project.  Here is a breakdown so far:

Date	Source	Description	Cost	Totals
12/31/11	Wag-Aero	Plans	$125.00	$125.00
06/05/12	Home Depot	Router Bit	$24.00	$149.00
06/15/12	B&D International	1/4” Plywood	$53.61	$202.61
06/06/12	Home Depot	3/4” Plywood	$74.50	$277.11
06/18/12	Aircraft Spruce	702' Cap Strip	$147.42	$424.53
07/01/12	Toziers	Parts for Steamer	$10.30	$434.83
07/02/12	B&D International	1/16” Plywood	$127.02	$561.85
07/02/12	Home Depot	Fine Cut Saw Blade	$43.45	$605.30
09/27/12	SystemThree	T-88	$71.72	$677.02
10/05/12	O'Reilly Auto Parts	Latex Gloves	$15.19	$692.21

Note that I have included only those items specifically related to building the airplane.  For instance, the new sander is not included in this list because it is a general shop tool that I would want whether I was building an airplane or not.  Specialty tools, are, and will be, included. 

The next logical question is;  how much time does it take?  Here is my time log to date.  The spreadsheet didn't copy over very well.  In future I will convert to a Word document before importing it. I also keep a paper log.

Date Task Hours Total 06/06/12 Assembled small fabrication table 1.50 1.50 06/07/12 Wing Rib Nose Block Pattern 1.50 3.00 06/08/12 Wing Rib Nose Block Jig 1.50 4.50 06/09/12 Wing Rib Nose Block Jig 1.25 5.75 06/09/12 Practice Nose Block 0.75 6.50 06/11/12 Calculated Ply needed for Nose Blocks 0.50 7.00 06/16/12 Wing Rib Nose Blocks 1.50 8.50 06/20/12 Wing Rib Nose Blocks 2.00 10.50 06/22/12 Wing Rib Nose Blocks 1.00 11.50 06/23/12 Wing Rib Jig 6.00 17.50 07/02/12 Capstrip Bending Jig and Soaker 2.00 19.50 07/02/12 Gussets 4.50 24.00 07/04/12 Gussets 4.50 28.50 07/09/12 Aileron Rib rear Blocks Jig & Blocks 1.50 30.00 07/10/12 Aileron Rib rear Blocks & Gussets 1.50 31.50 07/18/12 Glue Tests 2.00 33.50 07/20/12 Wing Ribs 3.00 36.50 07/27/12 Wing Ribs 2.00 38.50 07/29/12 Wing Ribs 5.00 43.50 07/30/12 Wing Ribs 1.00 44.50 08/03/12 Wing Ribs 3.00 47.50 08/06/12 Wing Ribs 1.00 48.50 08/07/12 Wing Ribs 1.50 50.00 08/11/12 Wing Ribs 2.50 52.50 08/13/12 Wing Ribs 1.00 53.50 08/17/12 Wing Ribs 2.00 55.50 08/18/12 Wing Ribs & Fairing Attach Blocks 4.00 59.50 08/19/12 Wing Ribs & Fairing Attach Blocks 2.00 61.50 09/14/12 Wing Ribs 1.50 63.00 09/22/12 Wing Ribs 3.50 66.50 10/04/12 Spent time with EAA Tech Adviser 1.50 68.00 10/05/12 Wing Ribs 1.00 69.00 10/09/12 Wing Ribs 1.00 70.00 10/11/12 Wing Ribs 1.50 71.50 10/12/12 Wing Ribs 2.00 73.50 10/16/12 Wing Ribs 1.50 75.00 10/17/12 Wing Ribs 1.00 76.00 10/18/12 Wing Ribs 1.00 77.00 10/20/12 Wing Ribs 2.50 79.50 10/22/12 Wing Ribs 1.00 80.50 10/24/12 Wing Ribs 1.00 81.50 10/27/12 Wing Ribs 3.00 84.50 10/31/12 Wing Ribs 1.00 85.50 11/02/12 Wing Ribs 1.00 86.50 11/03/12 Wing Ribs 5.00 91.50 11/04/12 Wing Ribs 3.00 94.50 11/08/12 Tail Ribs (behind fuel tank bay) 1.00 95.50 11/09/12 Tail Ribs (behind fuel tank bay) 2.00 97.50 11/12/12 Leading Edge Ribs/Tail Blocks 4.00 101.50 11/12/12 Gussets 2.00 103.50 11/26/12 Wing Ribs 2.00 105.50 11/27/12 Wing Ribs 2.00 107.50 11/28/12 Wing Ribs 1.00 108.50 11/30/12 Wing Ribs 1.50 110.00

Ribs, Ribs & More Ribs

Progress is re-started, after the Thanksgiving celebration.  Rib construction is the order of the day.  With 20 completed and 14 more to go there is not much to contribute to the blog. But I do have some thoughts.

The photo is of a pretty typical joint.  I have now made several hundred of these joints.  That would be 21 X 12 plus 25 X 8.  You do the math, I don't have my calculator handy.  I counted myself a pretty crafty wood worker before I started this project.  I have done everything from rough framing to fine scale models.  

But I got to thinking and evaluating after spending some time on William Wynn's FlyCorvair.com web site.  (Yes, Corvair power is a possibility for this aircraft).  William is big on education.  He is a proponent of homebuilding as a learning exercise.

This exercise, building all these ribs, while theoretically well within my skill set, has still taught me a lot.  The first of the capstrip joints are just as good as the later joints, such as the one above.  But I turn them out a lot faster now and with fewer discards due to mistake.  I have also learned to think in terms of production instead of just one part at a time.

There will be plenty of learning opportunities for me as the project moves along.  Once I have the ribs built, I need to fabricate the ailerons.  The aileron ribs are fabricated from sheet aluminum and the ribs are riveted to an aluminum spar.  I understand the theory and process, but I have never done it.  I have never formed parts from sheet aluminum. Except for a few very small pulled rivet projects, I have never set rivets. So that will all be a learning experience.

I am loving the process, but it is a challenge.

I find that many people do not tackle new challenges because they are afraid to let themselves fail.  How often do we hear, "Oh, I could never do that", when someone is looking at an example of fine craftsmanship.  But I think the main difference between those who "do" and those who don't, is that those who do are not afraid to fail.  OK.  There are exceptions.  My late, and highly respected, father-in-law could not work with his hands.  But he could do a great many other things and was never afraid to fail.

If you look at a project like this airplane and think it is something you could never do, you may want to evaluate your approach and determine if you are hampered by objective realities, or if you are simply afraid to fail.  

Happy Thanksgiving Everyone

There is not much happening during this Thanksgiving week. But no regrets. Lots of time for friends and family.

I thank God for all the blessings He has showered on me and mine.

Sander Report

My sander has been in service for a few weeks now, and I have developed a few thoughts on the thing.

This is the 9" Porter-Cable belt/disk sander.  After quite a bit of research and fussing, this is the unit I settled on as being the best choice within my price range.  With a package of sander disks and sales tax, the final damages were a few bucks over $200.00.  It seemed to be the sturdiest unit I could look at within my price range.  Everything I looked at was Made In China and so is this tool.   :(

This unit's performance has been, so far, quite satisfactory.  The table is very sturdy, and the unit is hefty enough to stay in place without having to be bolted to the bench.  I have yet to come even close to bogging down the motor.  But then, I am doing pretty light work, though lots of it, at the moment.

The dust collection system is totally ineffective when using the belt sander.  But then, it HAS a dust collection system.  The ancient and beloved Craftsman did not.  The dust collection system actually works pretty well when using the disk.

It actually has several advantages over the old Craftsman.  First, it is much quieter.  The Craftsman's mechanism was completely open with the motor mounted under the bench driving a V-belt, and the bearings have been in rough shape for a long, long time.  I also like the larger disk (the Craftsman was a 6"). 

Something I REALLY, like over the Craftsman is the speed.  The Porter-Cable operates at a much higher rpm than my old tool.  The result is the ability to do some very "light touch" work.  Much as I hate to admit it, this tool allows a higher level of accuracy, due to the high rpm, over my old standby.

On balance, and so far, I would have to say that this is a tool I could recommend to a friend.

New Ribs

I had the opportunity today to start the process of fabricating the additional 14 ribs.  Recalling an earlier post, I have decided to replace the leading edge ribs with full ribs.  Though I have more than sufficient material on hand, I need to turn that material into the various small parts that make up a rib. 

The first step is fabricating the rear end blocks.

I decided to build these blocks using the band saw and the sander instead of cutting them out using the router.  I just didn't feel like reconfiguring the shop for the router operation (a big disadvantage of a small shop, things have to be re-arranged for different operations) and I feel confident in my skill with the band saw and sander. 

Task #1, above, is to cut a pattern.  Using a single pattern is preferable so that any variations are not magnified from copy to copy.  The pattern takes particular care to ensure it is accurate. 

The above photo shows the pattern, cut from plain ole 1/4" ply, as opposed to aircraft grade.  All of its dimensions have been checked. 

The photo also shows the outline of the pattern traced onto 1/4" aircraft ply.  I had these squares left over from a previous mistake.  :)

I have found it advantageous to think out the production process, rather than considering fabricating one item at a time, so that all the parts are ready to hand when it comes time to fabricate the rib.  Thinking in terms of production instead of piece-by-piece fabrication really speeds things up and ensures a more uniform finished product.

Next I drew guidelines to cut the square into individual rough blanks.  Even when doing a non-critical cut such as this I find it helpful to draw lines.  It keeps me from making monumental mistakes...most of the time.

Here is the stack of blanks after cutting them apart on the band saw.  There are actually 16 blanks here.  I only need 14, but having two extras gives me the opportunity to make two mistakes without having to cut additional blanks and/or blocks.

The finish cuts are made on the sander.  The straight cuts get done on the disk...

The inside curves are done on the belt. 

A finished end block.

After a couple of hours of work, a stack of 15 end blocks.

But wait.....didn't I say I started out with 16 blanks???  Yep!  A small cutting mistake turned one of the blanks into scrap.  It always pays to plan for mistakes. 

Cooler Temps

Fall has definitely arrived here in the Pacific Northwest, with winter right behind it.  With the cooler weather I have fired up my little kerosene radiant heater to keep the shop comfortable.  It works great.

Obviously, I only run the heater when I am working in the shop.  The result is that the shop gets good and chilly when I am not around.  One result of that is that the T-88 gets really difficult to coax from the bottle. 

Sooo, on days when I am planning to glue, the T-88 goes in front of the heater first thing.

The distance has been chosen so that the T-88 gets warm, but not overly so.  It really improves the flow and decreases the time it takes to mix a batch.

Questions

A friend of mine who is intrigued by this project was confused about how the idea of a steel tube fuselage works:

This is a photo of Mike Finney's fuselage prior to covering.  His airplane is a Wag Aero Cub, rather than the Wag-a-Bond, but the construction approach is identical.

The fuselage is composed of welded 4130 (chrome-moly) steel tube.  It ends up covered in dacron.

Another Change

I just read the excellent article in the EAA Sport Aviation magazine about Mike Finney's shortwing Wag-Aero Cub.  What a beautiful little airplane. If you are not an EAA member, you can access the EAA online magazine "Experimenter" on the EAA website.  There is an article about Mike Finney's plane there, too.  Just go to the EAA website (via Google), go to the Multimedia tab and click on "Newsletters".  You can handle it from there.

I have corresponded with Mike on the Yahoo Groups site for Wag-Aero plans-built aircraft.  With all that, I got thinking.  One of the aspects of his airplane is that there are not leading edge, or "false" ribs.  He built full ribs for those locations instead.  The Wag Aero Cub wing is essentially identical to the Wag-a-Bond wing.

I also got thinking about the history of the Piper Vagabond.  The Wag Aero Wag-a-Bond is essentially an exact copy of the Vagabond. There are some changes.  The Vagabond was one of the first Piper aircraft to use aluminum wing ribs and spars instead of wood.  The Wag Aero wing is, essentially, an exact copy of a  pre-1947 Piper wood wing. 

Post-war (WW2), Piper was struggling financially.  They were building great airplanes, but they were doing so as economically as possible.  So, in all likelihood, the leading edge ribs were necessary for the leading edge of the wing, but an adequate wing could be built without full ribs in those locations.

However, if full ribs are installed in those locations, the result would be a stronger wing, and with more secure attachment of the fabric.  So, the additional ribs result in making an adequate wing better.  The weight penalty is actually pretty small, maybe three pounds.  Ribs really don't weigh very much. 

The downside is about a 70% increase in the amount of materials used, and probably just about double the fabrication time for the ribs, and a substantial increase in labor stitching the wings.

It just so happens that I blew the material takeoff when I ordered the spruce capstrip.  I have well over half of the capstrip I ordered sitting unused.  I also have sufficient material to cut the gussets and aileron rib tail blocks.  The nose blocks, which are needed for the leading edge ribs, are already cut.

So I could build full ribs instead of leading edge ribs at no additional out of pocket cost.  It would mean I am not finished building full ribs (and I have just shy of 100 hours into ribs now) and when covering time came the stitching would require a great deal more labor, but...no, or very little, out of pocket increase in cost.

For a better wing...

I'm gonna do it! 

Short Ribs - Not on the Grill

All of the "normal" sized ribs are complete:

It makes quite a nice pile.  There are 12 aileron ribs and 8 full-length ribs.  Still to fabricate are two tip ribs (slightly smaller cross section), two tail ribs that go behind the fuel tank bay,  two leading edge ribs for in front of the fuel tank bay, two leading edge ribs that match the tip ribs, and 14 leading edge ribs. 

I started the tail ribs today.

These ribs extend from the front of the rear spar to the back of the wing.  Here are the longitudinal members cut and fit.  The steel rule aligns the end of the members exactly with the front edge of the spar.  I also had to add a couple more alignment blocks right at the spar so that the vertical member would not push the horizontal members out of alignment. 

Here is the first tail rib fabricated and glued up.  It sure didn't take long. Now I just need to wait for the adhesive to cure before I can pop this one out of the jig and start on the second one.

I had hoped, dear readers (and there are an astonishing number of you), to treat you to some aerial photos today.  We finally got a small break in the weather and I abandoned work to take advantage of it.  However, when I got airborne I found that a "significant convective event" (thunderstorm) that I thought was stuck up against the mountains, was moving towards the airport.  Not wanting to get shut out of my home field, I circled back and landed after a short flight.  Sorry, no photos.  But I did get to fly.

Another Day - More Ribs

Just for  those of you who think you can't do this because you don't have the space....

This is a photo of about 3/4's of my little shop.  It can be done.  The two cardboard boxes contained the new sander and the little radiant kerosene heater that I bought.  I have kept the boxes for a little while to be sure the products don't have any out-of-the-box problems.

The radial arm saw, being the power tool I use the least right now, has become the catch-all horizontal surface for all the misc. bits and pieces.  Also, the older table saw is serving as a desk.  You can't see it because the plans are draped over it.

Once all the ribs are done and varnished, the two table saws and maybe the radial arm saw will be moved to my hangar to make room for the fabrication table.  My fabrication table will be modular.  The full table needs to be 4' X 14'.  My table will consist of two 2' X 8' modules and two 2' X 6' tables.  That is so I can configure a fabrication table to meet the current need.  For instance, I will only need a 2' X 8' table to build the ailerons, but both the wings and the fuselage will require the full 4' X 14'.

The aileron ribs (wing ribs that include the aileron wells) are complete...

 The closest stack is the pile of aileron ribs...all 12 of 'em.  The further stack contains the completed full length ribs.  I am in the process of building the last two of those...

They are the #10 ribs and are plated with 1/16" ply from the rear spar back.  Building the plated ribs requires a little creativity.

The big challenge is plating the "up" side.  It can't be done in the jig.  In the area that is to be plated the capstrip pieces are end-glued in place.  Grain-end glue joints are very weak, but they serve to hold the pieces in place until the rib can be removed from the jig and the process of fabricating and gluing the plate can begin.

The rib is gusset side down because it is easier for the sizing step.  This rib needs to have the plate installed on the side on which the gussets are already installed. Once the plate has been fabricated, the rib will be flipped over.   The piece of ply is the blank from which the plate will be fabricated.

The outline for the plate is traced onto the blank using the rib as a guide.  Care is needed as those end grain glue joints are very weak.

And the plate is rough-cut on the band saw.  And, yes, I know about the color balance variations.  Live with it!

A check fit, and, sure enough, the plate is just a tad oversize in some areas.  A pencil line is drawn on material that needs to come off.  Note that the rib has been flipped over. 

And the high spots are trimmed off on the sander.

Perfect fit.

And the outline is traced onto another blank for the plate for the other #10 rib (one for each wing).

I cut and fit all the pieces for the second #10 rib, shown here in the jig, before gluing up the plate on the first #10 and the gussets on the second #10.  I have used heavy bolts to hold the plate in place on the first #10 rib.  They apply enough pressure to keep the ply flat, but not so much as to "starve" the joint, a big sin according to SystemThree (the manufacturer of the adhesive).  Once all this is cured, the first #10, the one not in the jig, will be flipped over and the flip side gussets glued in place.   

Applying the plate to the second rib will be easier.  As there is a rib for each wing, the plate will be on opposite sides of each rib.  Note that the gussets have been applied to the rib in the jig.  With the gussets in place, it is a simple matter of pulling the rib from the jig (once the adhesive has cured), flipping it over, and installing the plate along with the flip side gussets.  A piece of cake compared to carefully end gluing the capstrip (making sure the rib doesn't get glued to the jig), and, once the glue is dry, veerry carefully removing the rib from the jig for attachment of the plate. 

Ribs won't be done with these last two full length ribs, though.  I will need to build 18 "false" or leading edge ribs, two partial ribs that install behind the fuel tanks,  and two tip ribs.