Rebuilding Station Zero

One of the many problems this fuselage had when I bought it was that station zero was located in the location outlined in an old set of plans. More current plans have it moved three inches farther forward which will give better ground handling and more room for the pilot. I'm short, but I like reclined seating, so I should have plenty of room.

I cut off the old station zero a long time ago and am finally getting around to rebuilding it.

I bought extra thick tubing and turned it down on my lathe to fit inside the 3/4" longerons. Those are the four shiny pieces. I'll cut the two pieces along the top at an angle to form the four extensions to the longerons.

Cutting the longeron extensions at a 30-degree angle.

Inner sleeves in place.

About 1/8" in between the two outer pieces, and cut at 30 degrees (approx.), as called for in FAA AC 43.13.

Welding it up.

Fast forward. I cut four pieces of 5/8" square tube 3.5" each. Those are in the corners. The 1/2" square tubing goes all the way across. Actually, they stop shy of the corners by about an inch-and-a-half, where the engine mount holes will go. The larger and smaller tubes are joined using a half dozen rosette welds.

I started by drilling a small hole in each corner where the engine mount bolt will go.

I used larger and larger bits until getting to 1/2", just under the dimension of the 5/8" square tubing in the corners.

You might think these tubes will be extremely weak for bolting the engine to, but not after welding in the bushings. They should be even stronger than the un-drilled square tubing.

Holding up one of the corner gussets to check the fit. Also, I used a scribe from the other side of the hole to mark the location to drill.


I had actually welded two gussets in place before, but I wasn't happy with them, so I ground the welds, removed them, and remade them. You can see the remnants of the previous welds.

Drilling 1/2" holes in the corner gussets.

I took 1/2" 4130 rod, mounted it in my lathe, drilled undersized holes, and cut to it length—actually longer than final—as the engine mount bushings.


Gussets mounted on the extra long bushing.

Test fit. Looks good.

You can see why I claimed that this will be stronger than just the 5/8" tubing by itself. That's a fair amount of beef.

Due to the welded bushing, I had to hog out the 1/2" hole in each corner gusset to fit tight against the plane of station zero.

Good fit of the gusset over the bushing. Lined up and flat against station zero.

Mostly welded up. I'll still weld the corner and a cap over the open end of the longeron.

I'll grind off the bushing which is still protruding out of the gusset and ream out the hole for a good fit of the engine mounting bolts.

One of the reamed engine mount bushings.

One corner, mostly done. Still need to weld up the corner.

The engine mount bolts fit very nicely through the bushings. I still plan on buying a face spotting tool and facing the gussets just around the bushings. The tool will use a 3/8" pilot (same diameter as the hole) and will guarantee that the faces that the engine mount on the front, and washer and nut on the back, rest against are perpendicular to the hole. This is important, as a non-square surface would cause asymmetric force on the bolt (or engine mount tube) which could break under the load. I know my holes aren't perfectly square to the gussets, so this will give me peace of mind that the mounting of the engine to the fuselage is sound.

Rebuilding station zero was a ton of work, but enjoyed it. Now it's according to the plans. I will enjoy both the improved ground handling and being able to recline in a comfortable position.

Making Brackets

I've been doing a fair bit of work on the plane recently. One of the things I've been doing is making brackets. There are lots of them and of varying thicknesses, from .035" up to .090". Ages ago, I made templates out of poster board of all the brackets required for this plane. They're all on one big sheet in the plans.

The first thing I did to make the brackets was to trace over the poster board templates with a scribe. I tried to fit as many as I could into the smallest space possible. No need to waste metal if I could avoid it. The limiting factor to how closely I could squeeze them together is being able to cut them out while not cutting into the outlines. If you're creative in the cutting, you don't need to waste much metal.

You can see my tool of choice here—or rather the tool that I have that will work. A band saw might be better, but to cut steel, you need a band saw that will let you run the blade very slowly, and I don't own one of those, nor to I have the money right now, nor do I have the space. The angle grinder actually worked really well.

Photographs of sparks are really cool. By the way, watch out for super sharp edges after the cutting. Also, the metal gets hot. I just let the pieces fall onto the concrete floor after cutting and let them cool off down there.

The next step after cutting out the raw bracket shapes was to get the corners ground off and get up to the lines with a bench grinder.

A nice pile of brackets, edges filed and sanded smooth. The two brackets on the left center are the aileron horns. They attach to the inner end of the aileron torque tubes, and control wires attach to their two ends. Anyway, those are aluminum and are actually .125". The rest of the brackets are 4130 steel.

Fabricating Rudder and Brake Pedals

So after a hiatus, I'm back at it. As you can see, I'm doing some metal work. This is all 4130 chromoly steel of varying diameters and thicknesses. I've never done any metal fabrication or oxy-acetylene welding, so I'm practicing and learning. My practice consisted mostly of welding some T-joints on some tubing. That didn't seem too hard, so I jumped right into the real thing.

I figured I'd start with small, simple parts like the rudder pedals and brake pedals. The little pile of parts you see below are the parts for the two brake pedals. The little tubes are 3/8". It was tough not to burn away the edges on those and the plates, but the results weren't too bad. The short (1") lengths of 7/8" tubing ended up slightly out of alignment with the rest of the brake pedal due to normal movement from welding. That's something I'm going to need to learn to deal with, although I don't think it's going to be a problem for the brake pedals. They're pretty close.

 

What you don't see in these photos is the struggle I went through to get the brake pedals to fit onto the rudder pedals. I bought a 3/4" reamer from Grizzly thinking that I'd ream out the brake pedals and they'd slide beautifully onto the rudder pedals. Well, I was in for a rude awakening.

Even after reaming, they wouldn't even start on. So, I chucked up a rudder pedal in my lathe and ran some sand paper in the inside by hand. That wasn't removing material fast enough, so I got out my Dremel. With the part spinning in the lathe and a light touch with the Dremel, I thought it would work out well. With one of the brake pedals, I went a little bit too far. The fit was loose, so I thought I'd have to cut off the 7/8" piece and weld a new one on.

The other one wasn't quite big enough, and I got it stuck on the rudder pedal. It was probably a little bigger due to heat and after I got it onto the rudder pedal a little bit, it cooled down. Well, it wasn't on there very far, but it was really stuck. I put another short (maybe 3") piece of 3/4" in through the other end of the brake pedal pivot tube to try and tap out the rudder pedal from inside the brake pedal, but then I had three stuck pieces! And when I say stuck, I really mean stuck!

Freezing, heat, brute force, I tried it all. One thing I learned from this is that this steel is tough! So, after hammering and wiggling and swearing, I finally got them all apart.

I put the brake pedal back in the lathe and did a little more work with the Dremel. I also used a lot of elbow grease and smoothed out the rudder pedal tube onto which the brake pedal goes using sand paper. Long story short, I have a slightly looser fit than I would like, but I kept getting gouging when I would slide the parts together and this seems like the best way to go. I plan on putting grease in between the two, and a little bit of space will give some room for the grease.

I still have a little more work to do on the pedals, but just wanted to give you an update and let you know that I'm making some progress.