Tail Fits The Fuselage

This morning I took the tail surfaces over to my brother-in-law's shop.  I have the fuselage stored in his attic. The tail surfaces fit.  I need to weld up the Fin and add the brackets for it to attach to the Stabilizer.  Once those are done I can take it all back over to drill the mounting holes in the Fin.  The old lower cables (still on the fuselage) fit very close to the bolt holes in the fin, which helps me think the drawings were pretty close to how the stabilizers were built.

This really was a big day.  It's starting to look like an airplane again.  Very Cool!

Upper Rudder Hinge

These pictures are of the lower hinge.  It is made the same as the upper hinge but it is on the 1 1/4" tail post which the fin rear spar (1 1/8") fits into.  It's made form 16 gauge (.o5o") steel 1" wide.  The 1" wide strap which goes around the rudder spar is made from 18 ga. (.040") steel.  It bolts to the hole through the tail post and hinge.  That hole has a bushing in the tail post.  The bolt hole in the hinge is larger than the bushing O.D. which allows the 3 pieces to be welded together, with the weld below the surface of the hinge.  This lets the strap bolt on nicely.

The ends of the hinge are formed to fit the tail post and welded on all the way around.  The bottom of the hinge socket has a dimple running the full width.  It appears to have 2 advantages.  It provides a nice place to weld the hinge to the post without the weld being in the bearing area.  It also adds some gap between the rudder and fin to allow more room for the fabric covering, surface tapes, and dope.  I've never seen the hinges on a real stabilizer so it makes me wonder if they were really made in the same way.  The WACO TEN hinge drawing doesn't have this feature.

I started with a strip of steel about 7" long.  The first step was to put the dimple into center of the strip.  The vise was adjusted to have about 1/4" gap.  You can't see it here but there is a slight radius filed on the jaws and then steel jaw covers add a little more.  A 3/16" drill was pounded into the strip to form the dimple.  The strip is bent a little but the shape is perfect to start forming the socket shape.  The drill was pounded in to about 3/4 of it's diameter.

To clamp the part for forming and keep the dimple from flattening, I made a support block from a bar of 1/4" steel.  A 1/4" slot was cut 1 1/14" into the steel and the edges rounded to fit the hinge.  With the bar clamped in the vise, the hinge was clamped to it with a 3/4" socket to use as a form tool.  The ends of the hinge were bent around the socket as far as possible making a "U" shaped part.

The hinge with the socket and bar still clamped to it was held in the vise so the ends of the hinge could be bent 90 degrees to the socket.  OK, I was having fun and forgot to take a picture.  With the side "U" bends started it was stood back up in the vise and the sheet metal pliers used to bend the ends 180 degrees.  These bends were tightened a little with a clamp.  With the clamp still in place the ends were bent back to be 1-1/8" apart and close to parallel.  The bends to do this were made about even with the dimple.

To locate the bolt holes the ends of the hinge were squared to the fin in the jig.  The holes were then drilled based on this dimension from the formed ends.  I drilled the holes 7/16" dia. to give clearance for welding.

I used a slightly larger (22mm) socket to hammer the ends to fit around the spar.

The finished part fits great.  Now I just need the remains of hurricane Sandy to pass so I can use my outdoor welding booth.

Fin Tubes Fitted Up

 I've finally had a little time to fit up the tubes for the fin.  The plan is to tack weld it together then fit the tail surfaces to the fuselage, just in case the fin needs to be modified.  There's not much magic to it except the top tube of 1/2" steel.  It's flattened at the aft end and has a pin at the front spar.

 The flat side of the tube is supposed to be all on one side (the top) of the tube.  My first idea for flattening the aft end was to make a 1/2" thick block with a radius on one end.  I assumed I could flatten the tube in the vise.  The vise worked fine and the tube flattened very well.  The problem was the flatten area was near the middle of the tube, not on one side.  It also was not parallel to the top edge. You can see the bend starting to form in this picture.  The good thing was the nice radius the block formed in the tube.

 I realized the tube needed to be clamped against the backing plate to keep it from bending and force the tube to flatten along one side.  I used some pieces of plywood to clamp the tube.  If I were doing it again I'd use some steel pieces.  The wood let the tube move more than I would have liked, but I got there in the end.  I used the same block of steel and pounded it into the tube.  The back side was close to the edge of the tube and tipped up a little.

 Because I pounded on the block instead of squeezing it in the vice, it didn't form the radius as well.  To clean it up I used the side of a ball-peen hammer to improve the radius.  I used the hammer because I could hold the handle and pound on the head at an angle to drive it into the radius.  It worked great.

I then bent the tab down a bit so it would line up with the top of the rear spar tube.

 At the other end of this tube there is a pin which holds the front brace wire bracket.  I used a 5/16" hardware store clevis pin.  You might think a good AN pin might have been a better choice, but I had to weld this in place and didn't want it to accidentally harden while cooling.  Based on the stress analysis the loads in the pin are low enough that mild steel will be fine.  Besides this whole plane was originally made from 1005 steel.

I used a longer pin than needed so I can cut it down to fit.  There is a washer to protect the weld. Next the fitting is .095" steel and then there is a washer under the cotter pin.

Before I can weld the tubes I need to make the upper hinge for the rudder.  It goes at the top of the read spar.

OX-5 Blog

I expect there will be a few people interested in rebuilding an OX-5 but not my WACO project so I've created  another blog just for it and will post all my progress on the motor there.  As significant projects are accomplished I will post links to them here.

I now have an OX-5 Motor

While at the Antique fly-in at Blakesburg John Swander stopped by my booth to check on the progress of this project.  He had acquired 2 OX-5 motors some parts and a radiator.  After a little discussion I purchased them for $2800.  The motor you can see in the door is the most complete and hopefully restoreable. The other motor is on the other side of the van.  The motor mount is believed to be for a Travel-Air as well as the radiator.

 The valves on the best motor are Miller valves which use a grease fitting instead of oil holes in the castings.  The cylinders are also from a dual ignition OXX-6 motor.  The second plug hole is plugged with what appear to be factory made slotted brass plugs.

Both motors were made by Willis-Morrow Company of Elmira, New York.  The better motor has Manufacturer's Number M3607 but is missing the Army acceptance tag.  The other motor is number M2753 and was accepted 15 May 1918.  Since they built 12,600 engines, M3607 was probably made about a month later.

The extra parts include a header tank for the radiator and various water and intake pipes.

The prop hub on the left is not for an OX-5 but looks like it may be for a Hisso.

Some Berling Magneto cores and parts.

3 Zenith Carburetors.

Water pumps.

Standard OX-5 valve mechanisms from the second engine.

Intake manifolds.

Overall this is very cool.  The next step will be to start soaking all bolts, pistons, etc. with Corrosion X.  The plan is to clean up, repair and organize each item as it's removed.  The bigger problem is how to get the motors to the attic.  I probably will have to break it down to cylinders and case in order to store it while I'm working on each piece.

Stabilizer Incidence Angle

The stabilizer front spar lays directly on top of the fuselage upper longerons.  It is clamped there by a block of wood which sets under the longerons and is bolted to the front spar.  The brace wires are adjusted to keep it square to the fuselage center line. There is no elevator trim.  The angle of incidence of the stabilizer is not adjustable because the front spar of the fin bolts to brackets on top of the front spar of the stabilizer.  Probably not the cleverest arrangement, but it is simple.  Also the upper wing fore and aft position is adjustable with the rigging to balance the plane.

The factory fuselage drawing shows the upper longerons flat the full length of the fuselage.  On my fuselage the upper longerons are bent down 5/8" from the last fuselage bay (forward of the stabilizer front spar) to the tail post, as shown here.  The older drawing of the tail (7012) shows the same angle.  This bend lifts the stabilize angle about 3 degrees.  When Frank Pavliga test flew his NINE with the longerons straight he found a very tail heavy plane.  There are no other flying NINEs to compare handling. It looks like 5/8" is about what is needed to correct the tail heaviness.  If I ever find the lift, drag and pitching moment curves for the Aeromarine 2A airfoil I can do the math to figure this out more accurately.  The airfoil was tested at MIT in Dec. 1922 and the curves were apparently published in the 1925 edition of Handbook of Instructions for Airplane Designers.  Google claims to have the 1925 edition but its not.  I'm sure MIT has the original data and the Air Force museum should have the handbook since it was done at McCook Field.

Since I have a fuselage, this angle would have continued to exist on mine without a problem.  Unfortunately I don't have the fin so all this has been needed to figure out the correct layout of the fin to fit with the fuselage, rudder and stabilizer.

At this point I'm ready to get back to making the jig and fin.  I'm looking forward to fitting all this to the fuselage.

Stabilizer Brace Wire Bushings

 The brace wires for the stabilizer attach to fittings which are bolted to the stabilizer with 1/4" bolts.  The bolts go through bushings, short pieces of 3/8" tubing, which are welded to the front and rear spars next to the last full rib at the tip.  I needed some way to hold these in position while I welded them.  It probably isn't critical but I wanted them nicely square to the spars and lined up with each other.  I found a piece of steel channel I salvaged from an old fold up table a few years ago.  You know, one of those things you save because some day you'll have a use for it.  Glory be, I have a use for it!  How cool is that?
I cut 2 lengths long enough to hold the bushings next to the front of each spar.  Next I punched 1/4" holes in one piece and duplicate punched them in the second piece.  That way the bushings would be parallel.

 By grinding nice square ends on the bushings with the belt sander it all clamps together tight and square.  I used Stainless Steel bolts and nuts to hold the bushings tight to the channels.  Stainless doesn't get welded into the bushing so easy if I get it a little to hot.  The little piece of welding rod was used as a spring to center the bottom end.  The whole assembly just hangs from the top bushing.  I tacked each bushing to the spar and the ribs before removing the jig.

Originally it appears the bushings were either a couple inches inboard or not welded to the rib.  The rib on the stabilizer, but not the elevator, was moved outboard about 2 inches.  I think the bushing was originally just welded to the spar and the spar probably cracked so they moved the rib out to help support the bushing better.

I still have two tabs to add for mounting the Fin front spar but I don't want to weld them until I fit everything to the fuselage, so I'm sure the holes all line up.