Fuel Tank Cradle
Last evening around 630 PM, baseball practice was over, the kids had their homework done and my wife was eagerly awaiting the final episode of The Bachelor. After weighing the options, I headed for the hangar. I'm not a big TV person anyway.
The first thing I did was finish welding the right tail brace. Here is a picture after the bracket was tack welded in place. After a final fit (and a little adjustment) the final weld was made.
Here's the brace in place.
And a picture of both braces. These will eventually get a wooden fairing to make them more streamlined.
I was excited to put the fuel tank in place. That way I could hook up the neat shutoff valve linkage. The fuel tank sits in a wooden cradle padded with 1/4 in. felt strips. Each slat is screwed into a 2 in. steel sling.
Here are the strips screwed into the steel sling. For some reason, I was missing two wooden slats! Did I leave them back at the house? I knew I made the right number of slats. I searched the hangar. No luck. I was still short two slats.
I decided that I must have miscounted and made the wrong number of slats. This frustrated me because the slats were already cut, sanded, varnished, drilled, countersunk and ready for installation. Making two more slats would delay the fuel tank installation and I was not happy about it.
I accepted this fact and moved on.
Remember the slots that were cut into the firewall? The picture below shows why they were cut. The front of the steel sling protrudes through the firewall and gets bolted to the engine bearer (eventually).
I decided to drop the fuel tank into the cradle anyway. The missing slats were at the top and I could still get the shutoff linkage hooked up. With Glen Marsh's help, we lowered the original fuel tank into the cradle. I was pleased because the tank fit perfectly! I patted myself on the back because when I built the straps, I took great pains to ensure the steel was bent to the exact specifications on the Curtiss factory drawing.
All I had to do now was hook up the shutoff handle, right?
Well, the handle didn't line up properly. Why? I scratched my head and stared at the linkage. In order to make it work, I had to move the handle forward until the two rings cleared the seat rails. The rod took a terrible angle in order to meet the shutoff valve. That was not right. I looked at my file of Jenny reference pictures. They all had the fuel shutoff rods extended nearly horizontal. Why was this one different?
After much head scratching, I noticed that the top of the fuel tank did not line up with the firewall or the front instrument panel. For some reason, the fuel tank sat too low in the fuselage. That was not right either! The fuel cap and eventual fuel gauge would be sunken underneath the sheet metal.
I became terribly frustrated. What did I do wrong?
Sometimes, you got to drop the tools and walk away. That's exactly what I did. By now, it was late and I was tired. I took a picture of the Jenny with some of the original sheet metal attached and called it a night.
Today I figured out the problem.
I was missing two slats because there was not supposed to be a fourth set of slats!
Below you can see the slats in their sling. The fourth slat was supposed to go at the top of the sling. But when I looked at my Jenny reference photos again, I noticed that they only had three slats between the top of the sling and the bottom of the tank. But I built the tank exactly as the drawing showed.
Remember I told you that most of the Jenny drawings that exist are for the later D-2 version. Our Jenny is a JN4D version. The later D2 was an improved Jenny which was going to be built for the military but the war ended and the contract was canceled. Most parts were the same as the JN4D. Guess which part wasn't?
So for you eventual Jenny restorers, do not make the fuel tank sling exactly as shown on the Curtiss Drawing Number 644602 !
I already go the .090 steel straps in the back of my car to make the new straps. I feel better now. The next set of straps should be easier to make. I know how much to shorten them and I already made a set.......for practice!