Tuesday, November 26, 2013

Right aileron hinge

The holes for the aileron hinge also stiffens up and shapes the aileron. I almost did a huge mistake here because the ribs, only at the root and tip, pushes the two bent halves a few mm apart. When the aileron is laid upside down and I tried to push with a flat hand at mid span, the surface will come too far down. When released the aileron will have a nice banana shape. What I did was to push the edge down with a file to get the lower surface flat on the table, then hold the hinge in place with my thumb and the other finger at the trailing edge without pushing the surface down. It ended up 100% straight.

Had to try the Topgloss once more as well. This time I rolled on a thicker layer, then use a foam brush to smooth it out. It became better, but far from OK on an airplane. High gloss and brush and roller is not a good combination no matter what the advertising says. Also sprayed some transparent coat on a piece of aluminium that was sanded with 1000 paper. Looks a bit cool, but I'm not convinced.

Monday, November 25, 2013


Drilled holes for the ribs in the ailerons. A bit fiddling to make it all fit with all the cutouts.

The whole paint stuff is strange. When I oiled my floor in the new shop I used something called "concrete oil" for indoor use. The name is very misleading because it is no oil at all. It is an acrylic emulsion (latex paint) that soaks the surface and penetrates down into the concrete. When cured it binds the concrete together as well as making a smooth surface and is of course water proof. It is also used as a primer for epoxy floor paints. I am very satisfied with the result, it does exactly what it advertise.

This "latex paint" on airplanes is also an interesting thing, but confusing. I have looked at typical Norwegian house paints and there is no such thing as latex paint. What they call latex paint in the US can be vinyl paint, PVA (Poly Vinyl Acetate) or an acrylic emulsion, all water based. It can also be a mix. In Norway I have only seen PVA and acrylic emulsions. The difference is that the acrylic emulsions are superior to PVA. PVA is typically used on ceilings, and as cheap wall paint. Most acrylic emulsions are indoor paint. There are some acrylic emulsions for outdoor use, but most are alkyd paints, some are also acrylic hybrid water thinned alkyd paints. For vinyl paint I have only seen this primer I am using, but that is alkyd based, not an emulsion, not a "latex paint" in any shape or form.

This Stewart Systems looks interesting. My neighbor meant I could simply put a transparent cote directly on the aluminium sanded with 1000 or something sand paper. That could look very cool, but will it stick?

Sunday, November 24, 2013


Sanded down the test sheets. I will try to polish them in 14 days and see how that goes, not very optimistic though. Graham Smith at Sprite Aviation could tell me that they use rollers, but only on matt and  satin finish, never on high gloss. Makes sense to me. He also said they mix their own paint because the viscosity is very important and it varies with the actual pigment (color).

Cut the aileron led counter weights with my hand saw. That was several hours of hard labor. I wish I had a band saw.

Friday, November 22, 2013

Topgloss BR

Rubbed down the test sheets and sanded with 400 wet sand paper. I found that the rubbing down was unnecessary because wet sanding with 400 did the trick rather easily. It became really smooth. I thinned the paint with 10% thinner (Jotun number 7), but that did not help one bit, in fact I could see some spots where the thinner dissolved the first coat and the vinyl primer.

The only solution I can see is to apply one more coat (no thinner this time), and then sand with 400 and or 800 and polish the surface. I will apply that coat tomorrow, and try some other brushes as well, a foam brush maybe, and then sand it and leave it for 2 weeks to cure properly, and then polish. If that doesn't work I will dismiss Topgloss BR altogether, also for my boat.

I also tested the paint with acetone and the thinner, Jotun thinner number 7 which is 75% Xylene  and 25% Ethylbezene, and alcohol. All three dissolved the paint very easy. I hope this is because it is not cured yet. The paint is fully dry in 6 h, but is supposed to take at least 5 days to cure at 23 C. The thinner also dissolves the vinyl primer easily, while acetone requires some work. The "Quick" spray enamel paint withstands the thinner, but is affected by acetone a bit better than the vinyl primer. What a mess. In any case it shows that latex paint is not such a bad thing, very strong and flexible. The thing with latex paint though, is it can withstand almost anything except Xylene.

Also received the faulty ribs and spar from Sonex today, so I can start on the vertical tail, once I finish the ailerons.

I had hopes for this Topgloss BR, high tech Polysiloxane that is supposed to be specially made for brush and roller. So far it seems pretty much unusable. I painted my fiber glass canoe some ten years ago with a 2k paint using a brush only, and the finish is 10 times better than this Topgloss BR.


Wednesday, November 20, 2013

Tried the Topgloss BR

Lots of pigment in there and it is glossy, but the finish is nothing to be impressed of. I used the correct roller and finished off with a broad soft brush, as described in the manual. The problem is it is way too viscous to be smooth. Right now it seems back to polishing if not the second coat becomes much better tomorrow evening. Maybe some thinner will help, but to me it seems like it cures too fast.

The only good thing seems to be that it sticks to unprimed aluminium just as good as the primer.


I have to write this down before I forget. I have tried a whole bunch of primers now. Monopol wash primer, Monopol Strontium chromate epoxy primer, Scanox rattle can (no longer available), Biltema aluminium primer, Duplicolor aluminium primer, Duplicolor plastic primer, some old zinc chromate primer, Jotun Yachting rattle can Vinyl primer and Jotun Yachting canned vinyl primer. I have also tried rattle can top coats.

Biltema and Duplicolor gives a very nice finish and are very easy to use. They look really nice, but when testing physical and chemical strength they are extremely poor. A drop of acetone will destroy large areas.

The Scanox (quick) rattle can is a bit more difficult to use, but it is much stronger physically and chemically than Biltema/Duplicolor.

Monopol wash primer is really good. It is for professional use. But the surface is porous and therefore it must be covered with something. As a primer for outside top coat it is probably as good as it gets. But it really is not something to use inside the house, the VOC content and odor is beyond belief.

The Strontium Chromate Epoxy is the best overall. Extremely strong, yet only 10-20 micrometer thick, and can handle even Acetone in moderately amounts, and is totally corrosion proof. But, it is not for the house due to VOC and toxicity and it is a lot of work.

The old zink chromate rattle can is easy to use, but it is thick and not very strong. It is also practically impossible to get.

The Vinyl primer is a bit difficult to use from the rattle can. But when cured over night it is very strong, and it even handles acetone to some extent, not nearly as much as the epoxy, but remarkably well. It is the only one together with the epoxy that is 100% waterproof. It can also be brushed on, and this is really practical when priming only the mating surfaces. In addition it can be used everywhere, on all substrates, and it is non toxic. And of course, it is part of Jotun Yachting system with the Polysiloxane top coat and is available everywhere around here. I just hope the rolling of the polysiloxane turns out OK.

Ailerons, primer and top coat

Bought Topgloss BR (Polysiloxane) at COOP along with some rollers and other stash. Then I went to the drug store and got some 60 ml syringes so I can accurately mix smaller amounts of the Topgloss. The syringes were surprisingly inexpensive, 3.5 NOK or about 0.4 Euro a piece.

Finished deburring the cutouts in the ailerons and measured up all the rivets for the ribs. Then I scuffed a test sheet of aluminium to test the Topgloss. I primed half of it with the vinyl primer and left the other half, just to find out how the Topgloss is with primer and without primer. I let it dry until tomorrow. The sheet is actually a faulty piece of RV horizontal stab skin. I really miss my old priming booth when testing all these primers and coating.

I haven't heard anything from Jotun about using Topgloss BR with no primer, so I just have to try it and see how it goes. If this works out, I will coat the whole plane with Topgloss instead of polishing. I'm not too keen on coating the whole plane with this vinyl primer with rattle cans though. If a primer is needed, then my old Monopol wash/etch primer gives a really smooth and thin coat, if it is compatible with Topgloss. But it is also possible to thin out the canned version of the vinyl primer and spray it on with air and achieve the same thickness as the wash primer (30-40 micrometers). Theoretically a 35 micrometer primer covered with a 35 micrometer Topgloss BR gives a total added weight of approximately 2 kg. This weight penalty is nothing when knowing that the polysiloxane is better than any polyurethane out there. In the cockpit I can also use Topgloss BR, hopefully with no primer.

Then the whole plane will be "Pegasus Grey" with tips and cowling in "Draco Red" and maybe with some trimmings in Draco Red as well.

Tuesday, November 19, 2013

Cut the openings in the ailerons and Polysiloxane

Cut the openings in the ailerons, only deburring left. Also bought a new orange from Hagmans. It was a bit more difficult to get a good finish, but the amount of pigment was abysmal also here. 4 coats of orange, and I still can easily see through it, it's ridiculous. Obviously I am doing something wrong here.

Looking a bit closer at Duplicolor web site what I have to do is first a plastic primer (also for fiber glass), then a white general purpose primer (white primer for bright colors), then the color itself (2-3 coats) and then a 2k transparent epoxy coat (2-3 layers) to achieve mechanical and chemical strength. This is not exactly straight forward and easy anymore, and with all those coats, it gets heavy. I begin to understand why people like Latex paint or real aviation products. The problem for me is that aviation paint products are practically speaking impossible to get. They can be sent from UK or USA, but the cost becomes ridiculous because they are labelled hazardous goods.

Anyway, I had a real eye opener this evening: Polysiloxane coatings. Going for the Jotun Yachting line of products, I only need one coat of Vinyl Yacht Primer (spray or brush) which I already have, and one coat of Topgloss BR, and it will last forever. Topgloss BR is a new 2k polysiloxane coat especially made for brush and roller. It is supposed to be completely smooth and shiny, even when applied with brush and roller, which in fact is the preferable method. Polysiloxane is superior to urethane in all aspects as well as being non toxic, no isocyanates. Polysiloxane coats are completely resistant to UV and oxidation. Generally a coat of polysiloxane is more corrosion resistant, more weather resistant, higher chemical resistance, more temperature resistant, and more glossy than the usual 2 step epoxy primer and urethane top coat.

The "old" Jotun Yachting method was epoxy primer and urethane top coat. The new preferred method is 1k Vinyl primer and a top coat of 2k polysiloxane. The Vinyl primer is preferred because it is smoother (but also needed for wood). So I wonder, on an airplane it should generally be enough with only a coat of polysiloxane with no primer or anything. In fact what the vinyl primer does is only to make a smooth surface for the polysiloxane top coat when using brush and roller, but it could also be that Jotuns formulation of polysiloxane requires a primer for adhesion? I don't know, but my guess is that using polysiloxane directly on aluminium would require 2 or 3 coats because it spreads so thin. And then it is faster and better to use the fast drying vinyl primer that is smooth and can be smoothed further by sanding. The spreading is incredible. 1 liter last for 30 square meters, film thickness of 30 micrometer. The older urethane top finish have the same film thicness, but only goes for 16 square meters due to higher VOC content.

I have read several places that people are using some new paint system and using only brush and rollers, Sprite Aviation for instances. This can only be polysiloxane coatings I guess.

So I ended up "Acetoning" all the orange paint off the tips. From now on there will be only polysiloxane coats on the Onex, with some Vinyl primer here and there (if needed). But this also means that I have to wait until I have more surfaces to cover because the paint is 2k. Another thing is that Jotun don't have orange, they only have a whole bunch of modern non-colors and "Draco Red". So Draco Red it is. Under the inner wing section and on the underside further back I will have some gray polysiloxane to protect the aluminium during the winter.

Sunday, November 17, 2013

Measured ailerons

Cut the ailerons to correct length and measured up all the internal cutouts and ribs. Also deburred all the ribs and plates.

Changed the color from dark green to bright orange. Dark green is nice, but it's so dark that it only looks good in sun shine. Here in Stjørdal the sun is not something that is shining all too often, and then the airplane will look too dull and dark. With orange tips and cowling, the airplane will look similar in color to the picture of the Trial further down (or ordinary Sonex polished style with orange instead of yellow). I think that will look cool, also on rainy days.

The Duplicolor turned out to be really a turn down. The finish really is nice and shining, but there is too little pigment in there. It is literally impossible to cover anything if the prepped surface is anything but white, and when the Duplicolor plastic primer is transparent, there is a problem . The tip that was partially green is impossible to get orange, and the seems in the glass fiber (dark color) shines through. I am also skeptical about duplicolor aluminium primer. I tried to sand it, and it goes off in a couple of wipes. The Jotun Yacht vinyl primer on the other hand, is 10 times as durable and can be sanded to a smooth finish. I also tried the houshold "Quick spray" primer from Scanox, it is much more durable than the Duplicolor. At least the Duralac works really well, and that is the most important thing. The Jotun Vinyl primer can be put on anything, and it can be covered with 2k paint.

I put the dimple die in the drill and sanded it to #31 size, it took ages. On the rudder about 1/3 of the stems had to be sanded a bit. From now on all countersunk skins will be #31.

Saturday, November 16, 2013

Friday, November 15, 2013

Dimpled the H-stab

Dimpled the H-stab. Match drilled the rudder. Now I have to wait for Lasse (the controller) before I rivet the skin onto the skeleton.

I also tried the Duplicolor spray on the tip. It looked nice. The color is dark green. The process will be to use Duplicolor plastic primer on the fiberglass parts and Duplicolor aluminium primer on any aluminium parts I want to paint. Then on top I will use Duplicolor 2K clear paint. This should look nice and be very durable.

I saw on the EAA webinar that some actually use Latex paint. I think Latex paint in the USA is the same as we call acrylic waterbased paint?, normal house paint. It looked very interesting, but I think I will stick to Duplocolor car paint, or else I would have to experiment a whole bunch to find good Latex paint here in Norway.

Tuesday, November 12, 2013

Monday, November 11, 2013

Engine alternatives.

Searched the web to find possible engines. The default is the AeroVee, but there are surprisingly many alternatives with similar HP and weight, maybe lots more than I have found. I sorted them according to price. Realistically the only real alternatives for me are the Revmaster and the Sauer 2200/2400. They are more or less "plug and play".

Name Type HP max RPM (prop) HP cont RPM (prop) cc weight [kg] Price €
AeroVee 2.1 80 3400 80 3400 2180 73 € 5 114,72
Great Plains 2300 80 3600 76 3400 2276 75 € 5 231,71
Revmaster 2300 85 3200 80 3000 2331 77 € 5 765,48
Sauer 1800 UL 68 3200 65 3000 1835 64 € 8 067,57
Viking Honda 110 2300 100 2200 1500 81 € 9 498,24
Sauer 2200 UL 85 3000 80 2700 2234 66 € 9 838,72
Sauer 2400 UL 100 3500 90 3000 2332 75 € 10 873,37
Jabiru 2200 85 3300 80 3000 2200 64 € 11 333,54
Verner Scarlet 7H 110 3500 90 2800 4127 82 € 11 990,00
Rotax 912 UL 80 2200 70 2000 1300 72 € 12 218,29
D-Motor LF26 92 3000 89 2800 2690 57 € 12 600,00
Rotax 912 ULS 100 2200 90 2000 1400 75 € 13 584,16
Sauer S 2100 ULT 110 3000 100 2800 2161 76 € 13 971,39
Jabiru 3300 120 3300 110 3000 3300 84 € 14 550,80
ULPower 260i 97 3300 82 2800 2592 72,3 € 14 700,00
ULPower 260iS 107 3300 90 2800 2592 72,3 € 15 800,00
D-Motor LF39 130 3000 125 2800 3993 78,5 € 17 800,00
Rotax 912iS 100 2200 90 2000 1400 75 € 18 444,42
ULPower 350i 118 3300 102 2800 3503 78,4 € 18 800,00
Limbach L2400 EB 84,2 3200 82 3000 2424 82 € 19 500,00
Limbach L2400 EFI 100 3000 100 3000 2424 76 € 23 900,00

Elevators finished

Even the 31 drill is too small for the dimple die. Drill up all the holes to 30 and dimpled. A few stems protruded maybe 1/10 of a mm or less, which was easy to fix with a scothbrite wheel on a drill. So I think I continue with 30 drill bits for now. Also drilled the hinges on the H-stab.

Sonex will send new parts for the defect vertical stab parts.

Thursday, November 07, 2013

Drilled elevator skins

The 31 and 32 drill bits came today from Aircraft Tool Supply. The 31 drill bit works, but the 32 drill bit is nonsense. It is nonsense because the hole becomes too small for a cleco. Although it is possible to push a cleco in there by force, you don't want to do that because you will damage the skin. The cleco itself does not work properly when the hole is too small, the friction will be so large that the spring does not engage, so the cleco does not clamp the pieces together. I haven't tried the dimple dies, but I would guess also the 32 holes are too small for the dies.

Tuesday, November 05, 2013

Vertical tail

Deburred the vertical tail parts. Discovered that 2 ribs were defect, flanges were bent offset the center by several mm. The main spar channel was also a bit off center. Very irritating, if the Sonex people had just looked at them - once - before packing them they would have seen it. Tried to put the skin on, and somehow it fits.

Sunday, November 03, 2013

H-stab riveted

Got my new #30 drill bits on Saturday, drilled up the H-stab skeleton and riveted it together (still waiting for the 31 and 32 drill bits to be used on the skins). I know there is really no need to prime the internals of 6061 aluminium, but I just can't resist the urge to prime... Primed the thick parts with an aluminium primer from Duplicolor. That primer really feels nice, with a smooth and hard surface even though it is only 1K. Then I primed the mating surfaces using a brush and Jotun Yachting Vinyl Primer. That primer is supposed to be watertight and good, but the resulting finish wasn't all that good, it became thick and spotty.

The plan is to polish the airframe and use some color on the fiber glass parts and some of the aluminium. I would really like to use Jotun Yachting products, since they are available everywhere and they have this new system with high gloss 2K paint that that can be rolled on and is extremely durable. But the experience with the primer was not good, it probably has to be very thick to give a good finish, and then it becomes very heavy. Jotun also have a 2K epoxy primer, but then I am better off using my real aviation 2K Strontium primer (and that is just too much work and hazzle). Duplicolor automotive spray cans seem to be a better alternative right now, but will that paint last? Then I probably can use Biltema automotive paint at half the price (Biltema use some OEM paint from an unknown, but large supplier similar to Motip-Duplo). Both Biltema and Duplicolor is readily available and they have primers for plastic, steel and aluminium to be used under their color system.

Also tried my Duralac. Each rivet has to be dipped in that yellow high viscous stuff. Actually it's not that much work, because when dipped I can insert lots of rivets at the same time, they stay in place due to the viscosity. After that I just go over with my pneumatic rivet puller. For the external surfaces this yellow goo will not look nice, but the excess Duralac can be wiped off easily with paper and acetone, and still seal and protect the rivet and aluminium internally.

Friday, November 01, 2013