Friday, March 27, 2015

Thursday, March 26, 2015

Inboard rib and aileron paddle

Riveted the inboard forward fold ribs and fixed the aileron paddle. Can't find the last four fix nuts.

Light and Nuvite from ACS

Received the Aveo lights and the Nuvite polishing from Aircraftspruce. The lights are Aveo LSA. They are so called 3 in 1; nav, position and strobe. The Nuvite will be a nice Easter vacation hobby, together with aerobatic training in a Saab Safir.

Those lights are engineering marvels with a lifetime warranty. When ordering I forgot to order the landing/taxi light and when I remembered it Aicraftspruce had already packed the items for shipping. Have to order them later together with some other goodies. Need a ton of cables, knobs and so on also.

Painting the engine take 2

Painted the engine - again. This time with a more suitable and stronger paint in the color RAL 9006.

Monday, March 23, 2015

Painting the engine

Found out the "barbecue black" is dissolved by gasoline, and any other solvent. There will be no way to clean it when the paint dissolves. Maybe it will cure when warmed, but that requires at least 200 deg C. The engine casing does not get hotter than 100-120 degrees. The Power Coat 3 in 1 I have been used before takes 200 deg, and the RAL 9006 (aluminium color) takes 250 degrees, so I bought one can. The black went right off with silicone remover, but all the holes and corner was some work. Clean enough for a coat of powercoat.

All this paint stuff has been a real pain a certain place. This Power Coat is good though. The only bad thing is it cant be covered with PU. But now that I have decided to polish the plane, the whole PU "problem" is gone.

The Power Coat gives this satin/matte shine. I will use that for some trimming on the polished skin. That should look cool I think, and it's easy to use.

Wing fold and ribs

Deburred and primed all the details for the inner wing fold mechanism and rib. Riveted together the aft rib.

Wednesday, March 18, 2015

Aileron paddles

Drilled the holes for the inboard aileron paddles.

More connection rod stuff

Looked at the connection rod that broke and the new one Aeroconversion sent. I think I know some more of what can have happened. The rod consists of two pieces, the rod and the cap. The rod and the cap can be made as one single unit or as two units by forging or casting. After the forging or casting, they are machined as one unit. This means that each rod only fit with it's original cap.To prevent interchanging of rods and caps, they are imprinted with (semi) unique numbers. So far so good.

The original VW rods are too large when the stroke is increased to 82 mm. Therefore the rods needs to be modified, as well as the casing. Special long stroke rods are manufactured, but Sonex use ordinary VW rods and grinds them down so they fit. This grinding removes half of the threads, which is a rather odd thing to do (mildly speaking), but a more subtle thing is also happening. The grinding also removes the original unique number on the cap. This can be seen on the new rod I got, which was grinded much less aggressive than the original 4.

The number 929 is printed on the rod, and the same number is almost fully visible on the cap. On the original that is grinded more aggressively, a new number is printed on the cap. They have also used different (larger) fonts.

The number 744 is clearly visible on the rod, but on the cap something has happened. It seems as someone has made a printing error before grinding and then just corrected it. The number on the cap say both 774 and 744. What is clearly visible on the rod/cap (when looking) is the rod and the cap does not go together as one unit. The rod is 744 and the cap is 774. None of my other rods have these numbers.

The picture above shows the new rod with it's correct cap. They fit together like a hand and a glove. The picture below shows the old faulty rod, and it is clearly visible that they are made from different pieces.

Also when measuring the diameter of the main hole, the old rod is oval because the pieces do not fit together. Luckily the threads broke when I torqued it, also because of this mismatch and because of the small thread length. If they hadn't broke, then the engine would probably run for a couple of minutes, and a large bang would destroy the fun. I have to wonder though, what will happen to the poor guy who have received the number 744 cap?

Another thing is also important here. With the new rods I received from Hummel a detailed instruction followed. Here is step number 3.

The info written in large red letters is nowhere to be found in the Aerovee manual, and this is also very strange. Clearly that step is very important.

OK, the connection rod issue is sorted out. Time to move on with the engine. There is still the thing with the heads full of sand and I don't think I will be in a mood to mess around with an aerocarb.

Friday, March 13, 2015

Corrosion tests

Fetched the test sheet that I have had on my boat since the beginning of July. The boat is in salt water and there have been several storms since July last year. Before that it was laying on my veranda through the winter and spring. The veranda has wooden impregnated planks and no roof.

When I put it on my veranda I put some salt on it and water, and let it lay there on the wooden planks through snow and rain. When on the boat, I simply tied it to the light pole. I can see very little change since I took it off my veranda and on the boat. There may be a bit more galvanic corrosion around the rivets which were not dipped in Duralac. I can only conclude 3 things:

  1. Letting the (slightly salted) aluminium lay on wooden planks (basically on the ground) cause corrosion
  2. Letting the aluminium be on a boat in a real marine atmosphere does no visual harm, except maybe some added galvanic corrosion between the stainless rivets not dipped in Duralac and the aluminium.
  3. Duralac and primer prevents all corrosion, also the veranda type :-)
I should have put a fresh set directly on my boat, but I envisioned lots of added corrosion, so I didn't. Anyway, since the salt water marina must be some of the stupidest places to place an aircraft, and no appreciable amount of (added) corrosion is seen, any corrosion problems for me simply do not exist. I will continue using Duralac on the last rivets. It also has the added benefit of making them water tight, and I can be 110% sure absolutely no corrosion will occur. In essence, this result is much better than expected.

From a more scientific point of view, I think what is going on is this: The marina is a salty atmosphere and it is also more or less continuously sprayed with sea water when it is windy. But, it is also windy very often, and it is raining a lot, so the salt will either dry or get washed away rather fast. When laying on the wooden planks (on the ground literally), it will be wet more often, and galvanic and surface corrosion have time to happen. The ground itself is also full of organic stuff (moist rotting leaves etc) that creates a very bad environment for the aluminium.

This also means my unsolvable problem with painting is finally solved. I will simply polish the aircraft. This will mean some extra work each year, but no more than I do when painting my boat beneath the waterline each year. 6061 for small aircraft is indeed the correct material.

Set 1 (veranda + boat , veranda below).

Set 2 (veranda + boat , veranda below).

Sunday, March 08, 2015