April 10 Update

I've gotten several misc. things done the past couple of weeks.  Much of the work has been on cabane struts.  I'll devote an entire post to those and talk about my streamline tubing dilemma when they are done.  Here are a couple of pictures, though, of the diagonals.

Fitting barrel into streamlined tubing

 The diagonals are the only cabanes that are adjustable, with a forked terminal on the lower end.  I welded in a conventional barrel and then slit and welded the trailing edge to taper it down like the originals.

Finished diagonals with old terminals installed for mock-up

I delivered the fuselage to a local bead-blaster this past week.  It will be done a week from today.  Prior to sending it out, I added some additional stand-offs to the tubular stringers.  This will increase the rigidity of them and help to keep them from bowing in after the fabric covering is shrunk.

Fitting stand-off

The proper length of stand-off was cut to fit between the stringer and structural tubing.

Shown after welding

I then gas-welded them in place. A big improvement as some of the original stand-offs were several feet apart. Now, most about 1 foot apart.







There are strips of steel with threaded studs welded in that run on the upper longerons from the front to the rear cockpit.  These allow attachment of the sheet metal that goes around the cockpit openings.  Most of the threaded studs were in poor condition so I made new strips.

Old and new cockpit sheet metal attachment strips

Finally, some things are happening with the OX-5 again.  One of the issues I wanted to address were the pistons and rings.  The originals have 2, very fat compression rings with no oil ring.  In order to use them, I would have to have custom rings made, or put 2 rings in each groove.  I was not really happy with either option.  I have to think these fat rings cause a lot of friction, plus offer no oil control.  

I asked around, and found out that a company in California called Egge makes custom pistons and have made them for the OX-5 before.  Egge is well known in the hot rod market for flathead Ford and other engine parts.  I was concerned they would not be willing to make anymore aircraft engine pistons, but they were more than happy to.  I sent them dimensions, and with only a 5 week lead-time, got them last week.  They are a thing of beauty (only a true gear head can get excited about pistons!)

These pistons use 3 conventional automotive rings; 2 compression and 1 oil control.  This should be an overall improvement - less friction, higher compression and better control of oil.  Apparently, even in the early days of the OX-5, overhaulers realized the value of this type of piston.  There were aftermarket manufacturers of 3-ring pistons that offered an additional 75 RPM, more than likely due to less friction and better compression.

New piston on left, original on right

Inside view

Here you can see the difference in ring thickness.  Original on left
with 2 fat rings, new on right with 3 standard automotive rings

Next... I am going to finish the cabanes, and put some DP epoxy primer on the fuselage when I get it back.  Check back in a couple of weeks for the next update!