Sunday, April 16, 2023

Trimmed Trailing Edge of Ribs

 The ailerons use a folded ">" shaped piece of steel for the trailing edge.  Today you can buy a similar, aluminum, trailing edge material from most aircraft supply houses.  During WWI some of the aircraft, like the SPADs used a wire trailing edge.  That's how it's done on the NINE wings.

They use a length of 1/6" music (piano) wire for the trailing edge.  To hold it to each rib the wire is soldered to a strip of thin (0.020") copper, the width of the rib capstrips (3/8" for most ribs) and, about 3 1/2" long.  The copper is folded around the trailing edge of the rib and nailed to the upper and lower capstrips.  The noticeable thing about this method is that the tension on the fabric causes the wire to sag between each rib giving the trailing edge a scalloped look.  The wire sags in the shape of a Catenary Curve, like the cables on a suspension bridge (Golden Gate or Mackinaw).

To support the wire the ends of the ribs need to be square, not pointy, so there is a surface for the wire to bear against.

I had planned to make a fixture for the table saw, like I did for the Lead Edge wood on the nose ribs.  I forgot to do that and built the first 2 wings with pointy ribs.

I decided to make a fixture which would work for the ribs for these next 2 wings, but could also be used to go back and trim the ribs on the first 2 wings
After much rechecking dimensions the cut needs to be 20 3/8" from the rear face of the aft spar

For my fixture I used a piece of 3/4" plywood.  I need to cut out some holes in it to clear some diagonal braces on the wings so I needed it thick enough that it shouldn't break once I make those cut-outs.

There are 3 reference points to assure the fixture is in the correct position on the rib.  The 1st is the forward end of the fixture which rests against the rear face of the spar.  The 2nd, right behind it, is a block which holds the fixture in the correct vertical location.  The 3rd is forward of the trailing edge.  The rib sets down in the pocket resting on the 3rd stop.

I made a pocket, with another piece of 3/4" plywood,  just to get better control of the cut-off saw location and angle.  I wanted a nice square cut.
I used the square on these ribs to simulate the spar.

Once the rib was in the fixture correctly I clamped it in place at 2 of the vertical sticks.

A few gentile strokes with the X-acto Saw and the job is done, next rib.


A nice square end to each rib.

Look like I need to build wings.


Sunday, March 26, 2023

The Shop Is Ready To Build More Wings

 I can't believe I've done nothing on the WACO all winter.  My little free time was spent on a sticky valve problem on the Fly Baby, now solved & ready to fly.

I kept thinking I could build the wings in the other room of the attic, not possible.  Instead I moved the sand blaster and metal band saw to the other room.  They and the ShopSmith sat where the fuselage is now.  I didn't want to take the fuselage back to the hangar.

I now have about 6 feet clear in the middle.  It worked for the other 2 panels, so I think I'm ready to get back working on these 2.  




Wednesday, October 12, 2022

Last 2 Spars Routed

 The process for routing the spars worked very well.  It's worth going back and looking at the other posts.

The First One covers the guides and basic method used.

The Second One is about the much needed dust collector.

The Third One is about planing and sanding the routed surfaces.

By the time I did these last 2 spars I had forgotten what I did.  Fortunately I had these old posts to remind me how I did it.

I used the ShopSmith as my work table with roller stands to hold the spar flat.  Fortunately my attic is 44 feet long so I have room to slide the long (15') spars in either direction.
On the first spar I forgot to lightly cross clamp the guides to the spar.  The spar started sliding with the force of pushing the router.  The cross clamps also assure the guides don't move away from the spar, so you get a very straight edge.
The vacuum hose for collecting saw dust has to be positioned so it doesn't stop the router because the hose snags on everything.  I hung it from a nail by one of my skylights.


The routing itself goes pretty easy with slow steady motion, not across the grain.  Across the grain makes a deeper cut than with the grain.  WEAR EAR PROTECTION, it's noisy.  I use my Bose headset which I wear all day in the embroidery shop.

I used 2 drill bits, 1/64" smaller than the desired cut depth, with a straight edge to set how far the router bit protrudes beyond the base.  There's a picture in the first post.


The piece of 2x4 with the corners routed to 3/8" worked very well for sanding the rear spars.

Along with the 150 grit Sandblaster I bought some 80 grit.  It worked very well for the first pass on the rear spars, where I couldn't use the block plane or my rubber sanding blocks.

The last 2 spars are done.  How cool is that?


Saturday, October 1, 2022

Finished Drilling 2 Rear Spars

 

The attic is a bit crowded with the fuselage in there.  I should have turned the ShopSmith so the working side was on the left, where I had more room.  Hey it worked the holes are drilled and I'm ready to route the spars.

I only use the template to locate the drill, clamp the spar to the table, recheck the location, then move the template aside while drilling.  It's slow but the holes line up perfect.


Wednesday, September 28, 2022

Back To Drilling The Last 2 Wing Rear Spars

 Ok I've only drilled 2 holes, but I'm back working on the spars. The holes are the 5/16" holes which go vertically through the spars for attaching the wings.  Here are the links to go back and look at the details of how I did this for the first spars.

Aligning the ShopSmith to get accurate holes.

Positioning the drill.

Drilling the holes

After rechecking the alignment of the drill to the table and the fence we're ready to drill.  The spar is supported on 2 roller stands.  I moved the spar so the first 2 feet could be used to align it parallel to the fence.  The actual hole is 1-1/4" from the end of spar, therefore I wanted a longer edge to get it parallel.

The first pass is with a 1/4" drill.  The rear spars are 1-1/14" thick so I used a 1/2" gauge block between the drill and the table so the hole is centered on the spar width.  I center punched the holes with the optical centerpunch.

I clamped the spar to hold it flat and drilled just over 1/2 way through the spar.  Then the spar was flipped over and drilled from the other face of the spar.

The 2 halves of the hole aligned so well that a 1/4" bolt went easily through the hole.

I sort of repeated this process to drill out the hole to 5/16".  I used the 1/4" drill bit to align with the drill centerline, clamped the spar to the table, then switched the bit to a 5/16" bit and again drilled over 1/2 way through the spar, flipped the spar over and repeated.  After drilling the second side I used a letter P drill to open the hole slightly and in this case drilled all the way through, into my backing board.

Again a 5/16" bolt goes easily through the hole.

Now I need to drill all the holes for the fittings, etc.


Thursday, May 19, 2022

Templates For the Aileron Control Horn and Ribs

 

I decided to be more careful this time.  I've been using small blue tick marks to help me find my pencil marks on the galvanized steel, which I like for templates.  Depending on the light the pencil mark can be hard to see.  I confused myself on the last try by where I had made the blue marks.

I still think it makes drawing the actual lines much easier.

I used the optical center punch to mark all my holes and compass centers.

For holes I draw a small circle around the punch mark.  

For compass centers I put 4 tick marks, kind of like center lines.

I have this cheap plastic compass I like for most big curves. The pattern of holes and markings are set up based on the circle diameter, in 0.025" increments, so I rarely use my conventional compass.  It really works very well with my 0.5 mm lead pencil.




I drew the outline and 3 bolt holes first then added all the rivet holes.

After cutting and filing the outline I punched all the holes.

There are 3 pieces which all rivet together so the holes were transferred from the horn template to the other 2 templates.  The horn gets riveted between the 1/4" spruce rib on one side and a piece of 3/4" spruce, stiffener on the other side.  The rivets are Copper Rivets used for saddle and harness making.

The rib template can be used for the full length root rib as well as the 2 piece rib at the control horn.  I'm also using it to make a small rib jig for all the aileron Light Ribs, stick and gussets.

The control horn template can also be used to make the doubler which gets welded on to the forward end of the control horn.

Making Progress!


Sunday, May 8, 2022

Finally Back to Making Things - Well Almost

 The storm of January 3rd has kept me busy cutting up fallen/damaged trees for months.  I'm finally done with trees for this year.

I like to think I'm a good draftsman, but I've drawn this template on steel 3 times to get it right.

When I got it finished I decided to lay it on the drawing just as a final quality check.  I'm glad I did.  Some how I've located 2 holes incorrectly.  Pretty sad given I'm laying it out from my own drawing.

The good news is I'm having fun, even if I get to do this one more time.  Still, better than wrecking some expensive 4130 steel.

Back to the workshop.