building a glider

[quorneng]

I can't help with oil based polyurethane as I have never used it on tissue. I suspect it is pretty thick so will be hard to spray by any means without dilution. The problem is knowing wat would be a suitable diluting chemical. Not a problem withwater based o use.
I also suspect an oil based polyurethane will dry pretty slowly so will very limited 'shrinking' effect

 

[Tench745]

I haven't tried the oil based. It will behave differently when applying, but might have the same effect when dry. I really don't know.
For the water based, I just applied it lightly with a small, fine-bristled brush. It will make the tissue sag because it's full of water, so you have to make sure it doesn't stick to the opposite side while it's drying.
I did cover one model with tissue and Krylon spray. It works well and is pretty simple to do. The only downside I saw with the Krylon is that it is less resistant to moisture and humidity changes than the WBPU, but the ease of application may be worth the slight reduction in waterproofness.

 

[hello183]

I finished covering the fuselage. By the way there is no color scheme. Just white.
@Tench745 Does the krylon also shrink the tissue a bit? Also, I don't think that I would fly the airplane when it rains or something like that. The only moisture I think would get on it is a little bit of dew from the grass. So could it be fine for that?

 

[quorneng]

helo183
That looks good.
Unless you put on several coats of a sealant, but it will quickly becomes heavy, tissue can absorb moisture from even humid air so goes saggy. It will re tighten as it dries out but there is a danger the wing will end up with a twist in it.
Lightweight tissue covered structures are for dry warm weather conditions.

 

[Tench745]

View attachment 229482
I finished covering the fuselage. By the way there is no color scheme. Just white.
@Tench745 Does the krylon also shrink the tissue a bit? Also, I don't think that I would fly the airplane when it rains or something like that. The only moisture I think would get on it is a little bit of dew from the grass. So could it be fine for that?

Krylon may make the tissue sag slightly when you apply it but it will tighten up again when dry. Apply light coats to reduce this. I would not rely on the Krylon to shrink the tissue at all. Shrink your tissue normally first, apply the Krylon as a sealer last.

 

[CthulhuJon]

Toothpicks or small bamboo skewers work fine for the elastic bands. This is covered with tissue already but I just used two small skewers through triangle strengthener piece. Two small elastic bands hold the wing on..
Strong enough for a small , light, slow flying glider.

For shrinking tissue. You options are water, ezeDope, cellulose dope, krylon spray or heat shrink plastic covering.

Cellulose dope will give you the best "tissue" finish, it is waterproof but very stinky and toxic to use ( outdoors only ). Water is free, but in anything other than a nice dry sunny day the tissue will sag, then the plane will not fly, or fly badly.
EzeDope is non toxic/non smelly, but hard to get a perfect finish, hard to get better than semi-waterproof, better than just water, but still can sag in damp conditions, it toughens up the tissue, can be used indoors, overall its not bad, but not great. Krylon spray is easy, somewhat stinky with pretty ok waterproofing. Or if you can't get the tissue to work out... buy a covering film like "ultracote lite clear" ( about $16) and borrow a clothes iron to iron it on, waterproof, apply indoors, best finish. but tissue will be the lightest option.

Re-sharpening blades on sandpaper requires a very fine grit paper, and a consistent angle/sharpening technique. Check on YouTube for resharpening exacting blade videos. a whet stone/sharpening stone works better.
The main trick is a consistent angle.

 

[hello183]

I decided to recover the horizontal stabilizer entirely and today it is all shrunk well. If I fly it in the afternoon, it is then warm and dry because the dew goes away by then. @CthulhuJon I actually used a kabob skewer that ran parallel to the centerline of the fuselage to mount the wing. I can show you that later. If I was going to use any plastic wrap for covering the airplane, it would probably have to be packaging wrap, because it is the only thing I can find light enough. Also, I am using water to shrink the tissue and krylon to seal it. Also, cool airplane by the way.

I made a mistake in making the horizontal stabilizer, I didn't make the sticks where they mount to the fuselage sides thicker than it needed to be. Now the tissue has to be cut at the end of it and the balsa cannot glue to balsa. But can I just use a pin and poke holes through the tissue so the glue can reach the balsa in the stab? It will also get to glue onto the center stick as well, and that will be a balsa-to-balsa bond.

 

[CthulhuJon]

glue strength comes from touching surface area of the glued parts, so you might not get much surface area from poking tiny holes. I'd try cutting away (or sanding away) some of the tissue to expose at least a little wood surface to glue.
you might be ok just gluing to the vertical though. hard to say for sure

 

[danskis]

If you cut holes consider covering them with scotch tape. The first time hurts you a little as it implies a less than perfect finish but it works well

 

[hello183]

The only thing I could find was the Rust-Oleum matte enamel. Could I use this? I might use it on the test piece to be sure. Now that I did some research, I realize I might have to buy the Krylon online.

I might try to sand away the tissue from the edge, but the stick is like 1/16 of an inch thick and I think the glue from the tissue needs some of that area to stay on. Maybe I can get away with it gluing to the center stick alone, but I'll see.

 

[hello183]

I was looking for things to make a balancing weight on the airplane, and I found this rod at the hardware store. I used a hacksaw to cut off a smaller piece and I was planning on drilling a hole in the nose cone where the weight needs to be for the airplane to fly correctly after I have flown it and taping the piece over different parts of the nose cone. How is balancing normally done?

 

[Piotrsko]

Anything that has a high density is used. Traditionally people used coinage on profile hand toss, fishing weights of various sizes on bigger stuff. American pennies have a consistent weight

 

[hello183]

I am laminating to 1/16 sq balsa sticks to make the top bit of the rudder now. I also added a trim tab that should mount to the back of the fuselage. I tried to use this new SuperPhatic glue that I got with the tissue. It is a penetrating type of wood glue. But it was difficult to do this long area because the applicator tip did not fit on the bottle. When the glue dries, I will pin the lamination down and build the rest of the rudder. How are trim tabs hinged? Will copper wire or soda can material work? What would you use for surfaces 1/16 thick?

 

[hello183]

The first lamination did not work so well, so I did a new one using normal wood glue and it worked fine. I also finished the rudder. It looks a bit more basic than I thought it would.

 

[quorneng]

A novel use of Lego bricks.
The lamination looks good.
I doubt if there is a significant aerodynamic advantage in doing it like that but its all good building experience.

 

[hello183]

Thanks @quorneng. What were you referring to when you said you doubt there is a significant aerodynamic advantage? This is the tailplane put together again.

I think we have some .032 in wire someplace. Does anybody use that to hinge trim tabs for 1/16 surfaces?

 

[Tench745]

Thanks @quorneng. What were you referring to when you said you doubt there is a significant aerodynamic advantage? This is the tailplane put together again.
View attachment 229771
I think we have some .032 in wire someplace. Does anybody use that to hinge trim tabs for 1/16 surfaces?

You can use fine wire. You could also just glue a small tab of plastic or cardstock which you can bend to add or remove trim.

 

[hello183]

I glued the horizonal stabilizer on. I couldn't take the edge of the tissue off, so I just poked several little holes on the bottom of the stabilizer before I glued it on. How do you guys align the stabilizer and wings to the rest of the fuselage?

 

[Tench745]

View attachment 229878
I glued the horizonal stabilizer on. I couldn't take the edge of the tissue off, so I just poked several little holes on the bottom of the stabilizer before I glued it on. How do you guys align the stabilizer and wings to the rest of the fuselage?

Mark a point on the center of the fuselage up near the wing, measure from that point to the tip of the stabilizer on each side. When the measurements are the same, it's square to the fuselage. Same idea for the wing; mark a point near or at the tail and measure to the wingtips.
Here's an article that goes into a little more detail of the process.
https://www.flyingrc.net/squarewing.html

 

[danskis]

It might not be as accurate but I put the wing on and measure from a point near the trailing edge wingtips to the leading edge of the stab on both sides.