Thanks Pat,

Yes it gets cold and usually somewhat windy. Still it might be possible to fly up to November or even December. That is if they keep the flying field with full scale runways open on Sundays, I would not fly this on rough ground.

When new to the hobby, we used to go flying at -20 C, even on snow covered ground, but now it is not so easy. At that temperature we had trouble starting the engines, but with electric power that should not be a problem - and the motors will not heat up.

Bulent

May be some useful pics from the Munich-Oberschleisheim Museum.

Istvan

Thanks,

I will look there, if they have more photos..

The radial engined type could be more difficult to balance, the inline nose is much longer..

No development yet this week.

Bulent

I placed all fuselage covering templates on the silk and about 1/3 seems to be free; so I have some margin for error, at least on small parts. On the photo the right section had the first ones of the doubles already placed, so all the left section will be free. I guess the grain direction should be as in the photo; the cloth was cut on the front and rear edges, the right and left edges are the edges of the cloth.

The creases on the silk look not so easy to remove when dry - it has been folded for decades The cloth is supposed to be applied wet, as suggested in the instructions, but I wonder if it will tighten too much that way. Before the other side is applied there will be an uneven force at the edge.. I guess I should start with the small parts and see.. When applied dry, and wetted later, the tightening may be enough.

I applied lacquer on all surfaces to contact the cloth. That will act as glue, and also will keep the lacquer from being drawn into dry wood while I want it to stay on the cloth. Maybe I will give it one more coat, the user guide suggests three layers of dope, sanding in between.

Bulent

Hmm, making patterns for cutting up covering material is a new idea for me. Looks like a good idea.

I trust you are using a well ventilated room, or even outside for that dope application. I have a very low tollerance to the fumes, and as usual I'm just average.

Well, now that the house heater is on, I can not work outside. I try to ventilate the room as much as possible, but it is getting cold inside after some time as well. As I stated before, I will use the garage for large scale doping and painting - there I have a window fan. In any case my resistance to thinner is higher than that to cyano.

I covered one side of the elevator to see the process. I covered it dry except for the area around the fold, which I wetted. It seemed normal at first, but when I applied water to the whole surface and let it dry, only the wet covered area was tight, the others went slack - strange. See photo - the up-left side was wet covered. That must be why wet covering was recommended. I will try to shift the edges of the cloth on the elevator tonight by loosening the dope at the edges, or cover it again. I guess it was wise to try the technique on a small part.

I am not sure how I will cover it wet with those large curved areas - top and bottom. I may need an atomiser to keep it from drying during the process.

I received the acetate sheet now, the surface has many scratches I received more than one sq. meter of 0.25 mm sheet for around 4$ plus 3$ shipping, but I don't know if or how much of it can be used.. Maybe it can be polished a bit.

Bulent

When I put tissue on it's dry and stretched as tightly as possible over the piece, then I wet it and as it dries it shrinks tight and removes all the wrinkles.

Looks like with silk you want it stretched evenly (wet) when you apply it. Maybe it doesn't shrink as much as tissue and is therefore less tolerant to boo boos?

Hi ocmini,

As you said, it is not a material that shrinks readily. Applied wet, it works well.

I removed the covering on the elevator, because I could not get the cloth taut. Wet covering worked well. The rudder, elevator and one side of the vertical tail are covered. The wet cloth sticks everywhere, especially to itself, so it is hard to get the wet cloth unfolded and lying properly on the part. I tried correctly placing it and sprinkling it with water, that works better - but then water gets into the structure In any case, I covered the first parts - being removable helped much. Silk weight for the elavator was 0.24 grams (one side), when covered both sides it gained around 0.75 grams; so the dope weight, used as glue, was substantial. It looks like at least 4 layers of dope will be required on the whole surface, and that will be the real weight.

After covering the vertical tail, I noticed that the cloth was cut in the wrong grain direction, luckily only these two parts - I was careless. The cloth sags a little between the ribs, but I guess I will not remove it. I doped that side to see if it would behave worse after doping, but nothing much changed. I will let that be one of the mistakes on the model - it is not very visible..

I did not have 1/3 of the silk remaining after cutting parts, as I thought before, because I had forgotten that I needed 4, and not 2, of the horizontal tail and elevator covering pieces. I still have one reserve for the upper fuselage covering - that is the most critical part, with those curves. Sticking that to the narrow stringers may be an isue as well. The cloth dries up fast, because it is very thin and with open weave, it has to be kept wet during the process.

I added small triangular balsa parts around the exits of the elevator joiner wire, and also added a thin FR4 strip where the vertical tail's LE joined the fuselage.

I could not continue covering to prohibit excessive exposure to thinner vapors, but I brushed a layer of whitish surfacer to the nose and the doors.

Bulent

This is starting to look like airplane parts

Nice work with the silk.

charlie

Thanks, Charlie..

I guess I am missing the flying season again, so I may have more time to work slowly Still I am trying my best to finish this model, at least to flyable condition..

Bulent

I am trying to buy more of that silk, but it seems to have run out in Europe; or if they have it they ask 26 Euro shipment for a 10 Euro item (Conrad's fixed small package shipment price). This 14gr / sq.meter cloth was from Graupner, what they have now is 20 gr / sq. meter - if it can be found..

I can't understand why it is so hard to buy stuff from some EU countries..

Bulent

I sanded the tail fairing to a higher level of surface finish and then applied some dope/talcum filler - some air holes had appeared. The upper center section had the surfacer cracked and that section fell out because the part was flexing during sanding. I hope the talcum filler is more flexible.

I got pissed because the vertical tail's silk covering seems to have double trouble. The cloth developed a wrinkle; and also it got pulled down by the lacquer because the diagonal rib was a bit lower than the surface. The lacquer gets in between and pulls the cloth down, because the cloth gets loose when the lacquer is applied. Now I guess I have to remove the covering and raise all diagonal ribs up to the surface or reduce their width further. This holds for the horizontal tail as well, there the diagonal ribs are similar - it is good that this did not happen after covering that section. I also should look for real dope, which could tighten the cloth more. The cloth gets a bit tighter when I heat it up, but then it goes slack again. Problems never end..

Bulent

I learned that Graupner silk cloth will be available in Europe by November 15, and it looks like I could buy it from Holland. If the wings are not covered by then using Solite, I can cover them with silk, if I find the proper dope. I could also cover first with Solite and remove that for silk - or find that stupid when the time comes especially if the color match is good.

I had some of the dope recommended for the silk I used (Spannfix Immun), but no thinner for it; I learned from a German forum that acetone could be used. That may solve the dope issue for now, but the amount I have may not be enough for the whole model - and that dope can not be shipped internationally, as much as I know.

Bulent

I ordered acetone and ethyl acetate, which was suggested as the thinner for the Spannfix dope - which was suggested in the user guide for the silk. I have some of that dope, but the trouble is I don't know if it is butyrate based. It is fuel proof, so there is a chance it is. If that is the case, it looks like I can not use nitrate base paint on it. The paint I have must be nitrate based - no info there as well. I asked a German forum about the nature of Spannfix dope, but I doubt an answer will come - it was an old thread and my German is not good.

I have a feling my homemade glue could be used as contracting dope, but it will be risky to try that on this model - it is nitrate, but without any additives. I remember it contracted well when applied on silkspan for repairs. The German forum mentioned homemade dope using the German Uhu Hart glue dissolved in thinner so others have similar reasoning.

I also found some dope in my garage which is old, I had forgotten its existence. That might be proper dope used on full scale airplanes. I have to try it. I guess I will remove the dope on the vertical tail fabric and test the dopes on there, since it will probably be removed in the end - at least it should be of use while alive. I can also test my paint's action on Spannfix dope there. This will take some time, but it is better than ruining the covering and paint job at the very end.

I also ordered a 3M respirator with active carbon filters and dust prefilter, cost 55$ - local. Probably I will feel more comfortable using the mask while doping or cyano work. Filters are rated organics, inorganics and acid.

It looks like the temperature is rising a bit, 4-6 deg Centigrade rise expected.. The flying season may be extended.

Bulent