Tail wheel

The tail wheel mount need some modifications to get the bolt in there. The space is too small and the bolt is too far down and too long. I don't want to cut too much into the main structure. Seems there are two options.

1. Make a bolt with thread on both sides. This will be able to slip in from the side more easily
2. Make new angles with the hole further up.

I have to think some more about this, and ask what others have done. Maybe there are some much better solutions out there.

 
The engine paint. I have no idea what kind of paint stick on magnesium. All the paint available are made for cast iron, aluminium at most. Nothing really stick on aluminium without at least an etch primer, and then the primer also have to be heat resistant. VW did not paint the engines. "Barbecue Black" from the local home ware store therefore seems to be the best option after all.

Engine painting

Washed and cleaned the engine and masked off all open and machined places.

I also planned to paint it today using Auto-K engine paint. According to the web page at Mekonomen the paint is supposed to withstand 200 deg C, which should be more than enough for the casing, and I went down and bought 2 cans. But, I couldn't find any technical data sheet for that particular paint, and that was odd. The German site for the producer of the paint has a different paint, different part number, and didn't even have this "engine paint". Did some more research and found that Hagmans is the producer of "my" engine paint. According to the technical sheet there, the paint is only rated to 100-120 deg C, not 200 deg C. This is really annoying, paint is different and produced by different producers depending on where you live !!! Hagmans is a reputable brand, but "engine paint" reaching only 100 deg C ? I find this very strange, when the "original" paint from Auto-K is 300 deg C, and where does this faulty 200 deg C come from?

Now I'm not sure what kind of paint I will get. "Barbecue black", the "brand" Sonex themselves are using, is readily available, but I'm not too found of flat black, everything just becomes too dark too see. Biltema has some OK engine paint apparently, but is it really any good?

Paint is a real pain, more often than not. So far I have found and used two paint related things that works very well:

Silicone remover from Würth and Acid #8 from U-Pol (etch primer). They just work and the result is first class. I have ordered some boxes with gray 2K polyurethane to put inside the cockpit, I hope it works out well. I will find out during the next few days. This paint is industrial PU paint that Norbond fills up in rattle cans just before shipping. They must be used before 3-4 weeks.

Painting the outside of the AC is something I just have to start planning. My experimenting with rolling polysiloxane didn't really work out, impossible to get a smooth finish, and the polysiloxane cannot be polished (it gets white/flat and ugly). But now I have read about hobby car painters getting good results with Biltema polyurethane boat paint, spray and also with rollers. I have to try that, polyurethane sure can be buffed and polished, and I have heard nothing but good tales from boat owners using Biltema PU (even if some of their other paint is less than optimal).

The AeroVee engine parts made me scratch my head in disbelief today. The manifold enters the engine in two square channels. The engine on the other hand has two round channels. Why? this is simply unbelievable.

Engine case preparation

Cleaning and filing is needed on the outside and the inside of the casing. This is what an inside out and upside down VW beetle engine looks like.

Engine bench mount, inspector

Made the engine bench mount on the bench. Had to do a little modding on the mounts, but then the engine fits. Now I am only waiting for gasket stuff from Sandelwing before I can start putting the engine together.

Finished filing/deburring the brake mounts and primed them, as well as the titanium tail wheel leg/spring. Titanium is one of the most corrosion resistant metals there is, only gold is better. But it is also high up on the galvanic scale close to gold, aluminium is on the other end. There is no way titanium will corrode, but the galvanic potential makes it extremely hazardous for the aluminium, much more so than stainless steel. The best way to prevent any sort of galvanic corrosion to the aluminium is therefore to prime the surface of the titanium. When mounting it, I will also use some Duralac.  

Had a visit from my inspector. He is head of maintenance on Helitrans at Værnes. A Helicopter company with approximately 20 helicopters. He was very pleased with everything. There is a large chance I can do the last mounting and testing at their heated hangar. I really hope that works out because I have no other places to go that is close by.

Brake mounts, flap handle

Drilled and bend the flap handle. Cut out the mounts for the hydraulic brake handle and cylinder.

Fuselage, tail wheel

I have ordered the 6 inch tail wheel assembly. It came with the engine. At first look it looks really nice, clean design and nice black anodized parts. A closer look, and I was not so sure.

The first thing was the steel horn. It has sharp edges, and when swung to one side the edges cut into the cylinder holding the tail wheel titanium spring.

The first thing I did was to remove the steel horn and trim the edges son no interference was seen. Then I painted the horn with 3 in 1 paint, so it won't rust.

Then I noticed the but holding the bolt working as the axle. Common aerospace rule of thumb say at least one thread must show, but no more than 4.

Removed it and measured the bolt. New and one size larger must be ordered, preferably with a cotter pin, because the bolt could rotate if the bearings seize up.

The titanium spring rod was way too tight fit. Lots of trimming was needed to make it fit into the tail wheel assembly. Used the bench drill to drill the holes for the AN4 bolts as square as possibly (hopefully the holes in the fuselage that I made earlier is also correct)

Then I saw something strange abut the whole design. All the vertical forces and the torsional forces from the wheel is taken up small bronze bearings. These bearing are completely exposed to the environment. If that bearing last even for one single season with normal rainy weather and mud, I would be surprised. The bearings are easy and cheap to change, and the assembly seems both solid and light, but still.

All in all, the tail wheel assembly is OK. Light and strong, but requires some modding and probably yearly maintenance (changing bearings), but time will tell. Looks very nice though.

Made the handles for the wing folding mechanism.

Engine arrived

At last the engine arrived. Half a year after I ordered... Everything was there, engine, propeller, seat and lots of other bits and pieces.

Finished several small bits on the aircraft also.