Getting ready to make wing ribs

All the wing components are now complete except the ribs - they are next.  Fortunately, they will be fast and easy.  They are not a built-up truss-style rib, but cut out of a single piece of basswood with a spruce capstrip. 

Original rib

Here's another shot showing a compression rib also.  Nothing went to waste in 1928.  It looks like this compression rib was made from a shipping container!  Note the stenciling.

Andy is going to help with the ribs.  He made a template and we are simply going to cut them out on a router table.  What would normally take weeks and months if these were built-up, can be done in about a day!

Some additional comments about the airfoil.  Original factory brochures I have list the airfoil as a Gottingen 436.  I plotted one of these out, but it does not match the original ribs.  I also tried a Clark Y.  It is used on the OX-5 Swallow - still not right.  I tried several USA airfoils to no avail. Giving up, I decided to use the originals as a pattern .  Whatever it is, the airplane flew with these at one point in its life.

Drag & Anti-Drag Wires

Before I talk about the wires, I did get more fittings made.  Basically, all the internal fittings are now made.  The only ones remaining are for interplane struts and landing/flying wire attachments.


These are the fittings that attach to the spars and where the drag/anti-drag wires attach.  Made from .100 4130.






These have the same function as the ones above, but are used where the wires start and terminate, i.e first bay and last bay.  Also made from .100 4130












Drag & Anti-drag wires...
The wires are made typical to aircraft of this era - a length of piano wire (spring steel) with a loop at each end and a wire ferrule holding the loop closed.  Some manufacturers would solder the ferrule, others like Lincoln-Page left it un-soldered.  This method of making the brace wires was apparently an area of concern in the aviation industry at the time.  I've come across several in-depth test reports from the late '20's and early 30's testing various methods of making these wire assemblies and trying to improve on them.  It may be due in part to the difficulty in field-making these wires as special fixturing is required.  The later method of using threaded rod with clevis fittings on the ends is certainly a much improved method.

Photo of original.  The free end of the wire is bent around the
ferrule and is really the only thing that keeps the wire from
pulling out of the ferrule.

The wires are not too bad to make with the proper fixturing.  The challenge with these is forming the loop at the ends.  Luckily, I came across a very old aircraft mechanics book that showed how to make the fixture - although it's really not that difficult if you think about it.  The following pictures show the steps.

First - a length of wire is bent into a 180 degree loop

The loop is then put over the middle pin and each leg bent at
about a 45 degree angle

Assembly - a fitting or turnbuckle end goes in the loop, the ferrule is slid over the free end
of the wire and the free end is then bent over the ferrule.

                       

I am making up several of these assemblies to pull test and compare to the originals just to make sure everything looks A-OK prior to making all of them.

Wing Fittings

Since the wing fittings are so tedious and time-consuming, I decided to start knocking some of them out over the last few days.  Besides, the wings cannot be assembled until they are made.

Photo of original fitting on spar

I started with the easy ones first...  these are small brackets that go behind the fittings that the drag/anti-drag wires attach to.  Made from .062 4130.

These are the ones I made (plus the original) - 20 pieces required for all wings

Photo of original

I then tackled the more difficult fittings - the ones that attach to the drag/anti-drag wires. These required multiple bending forms and since there are tight bends involved, the parts had to be heated to prevent cracking. They are also made from .062 4130.

Here they are - all 20 of them.  Just need to be drilled - the easy part!

Detail shot showing all the bends. Once formed, the part has an autogenous TIG weld down the edge to hold it all together.

OX-5 Swallow wing drawing

I also got the rib locations marked on the spars for the lower wings.  I was able to use what pieces I have of the original spars plus drawings.  The drawings are worth mentioning.  Apparently no Lincoln-Page drawings exist.  They were destroyed in a flood - this even confirmed by a copy of a correspondence I have from Ray Page's wife.  (Ray was founder of the Lincoln-Page Aircraft Co.)  Fortunately, when Victor Roos joined Lincoln-Page, he brought with him all the drawings for the OX-5 Swallow which the LP-3 is a copy of.  I do have some Swallow drawings of the wings which do agree 100% to the LP-3.

Location of ribs marked on spars