November 14 Update - Cockpit sheet metal and OX-5

I got started in earnest on the sheet metal in the cockpit.  As I mentioned, Andy had some of this made back in the '60's when he bought the project from the original owner.  Most of it was just roughed-out and requires fit and finish.

Seat installation and upper sheet metal attachment strip

Left side sheet metal in rear cockpit

I've had the rear seat in and out numerous times, but never mounted.  Here it is secured in place.  Also shown on the top longeron, is a strip of metal welded on.  This is where the sheet metal that covers the top of the fuselage attaches.








I started fitting and mounting the side pieces too in the rear cockpit.  The open areas are where the long-grain cobra leatherette material is laced in. The instrument panel attaches to the piece going across the top.

Note:  these were all painted gray as per the original parts.  They will all need to be stripped and repainted.  I meant to take some pictures of the original panels (I will in the next post).  The paint work is interesting - there is one coat of gray paint rather crudely brushed on these parts.  Looks terrible!

Baggage door latch

Back side of latch

Here is the original baggage door latch.  It's made out of brass, so it cleaned up just fine.  I have some super-fine glass bead media that is like powdered-suger.  works great for stuff like this.    

Form block for door

Finished door with hemmed edge - inside

Finished door outside with restored latch installed

The latch spring was broke.  Installing a new one made it work great.















I had to make a new door to fit in the original panel.  As you can see, the door has a hemmed edge all the way around.  Easy to make.  All you need is a wood forming block.  Trim the metal about 1/2" oversize on all edges.  Slowly work the metal over the edges with a crown-faced body hammer.  After being bent 90 degrees, remove it from the forming block and finish tapping it over until flat.  3003 H-14 works best for this as you can bend the metal over on itself without it cracking.



































Some more OX-5 work was also finished...

Bushing to adapt rod to fixture

Checking rod for twist

 The next major step will be installing rods, pistons and cylinders.  There are a few important things to check on the rods prior to this - the straightness.  If the rod is twisted or bent, it can cause  piston pin bushing wear, cylinder wall/piston skirt wear and the rings to wear prematurely.  My friend, Mark has device to check this.  It's a precision machined/ground fixture that supports the big end of the rod and then measures  the twist or bend at the small end.  



We first had to make a bushing to fit the big end on the support shaft.  Once installed, the twist could be measured as shown in this photo.  The blocks the piston pin is sitting on is precision ground parallel to the shaft.  Feeler gages slipped under the pin show any twist.  A few rods required some minor tweaking (manual says to heat up and bend straight).  After adjusting, all were .0015" or less.

Checking rod for bend

Here, the rod is being checked for any bending.  The pin is placed against the vertical face of the blocks, and a feeler gage used again for clearance.  All these were .0015" or less with no adjustments required which is good as adjustments in this direction would be tough!  The rods are 8.25" pin-to-pin centerline.  .0015" over this distance is pretty good.

Valves installed in all cylinders

Straight-wound intake and barrel-shaped exhaust spring

 Also got the valves and springs installed on the cylinders.  It's important to check the valve spring load as they are not that high to begin with.  The Curtiss manual calls for 16 lbs. at 1.625" for the intake and 35 lbs. at 1.625" for the exhaust.  Some other manuals I have spec 40 lbs. for the exhaust.  My exhaust springs are original and in perfect condition.  The loads measured between 36 and 40 lbs.  I'm OK with this, I was more concerned they had taken a set and were too low.

My intake springs, though, had a lot of variation in the load, so I had new ones made.  They are now all exactly 16 lbs.  A comment about the intake springs...if you view images of OX-5's you will see barrel shaped intake springs (like the exhaust) and straight-wound ones.  Maybe Curtiss had multiple suppliers for the springs that made them differently, or maybe Curtiss made a design change.  My engine was built in January of 1919.  One of the last ones made as production ended early in 1919.  I tried to call the Curtiss engineering dept. to find out, but my call was never returned!!

Exhaust deflector

Not sure why Curtiss used the barrel-shaped spring.  It does offer more lateral stability as compared to straight-wound springs.  They also offer an increasing spring rate as deflection increases.  Maybe I'll get an answer from Curtiss engineering!



Here you can also see the exhaust deflector I mentioned in the last post.  It protects the spring if the exhaust gasket blows.  I made mine from .032" 4130 and black-oxided them.





Next, will be more interior sheet metal work and cylinder installation.  For now, it's time to sign off.  It's Saturday night - time to watch The creature from the black lagoon on Svengoolie.