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Piper Cub J-3 Build Log

MarioGdV

Active member
#1
Hi! As the title says, I'm going to build my first balsa kit, a 1200mm Piper Cub J3. It's definitely a bad choice for a first kit, since it's from Banggood, but I've read the instructions and I think it doesn't seem that hard. However, I can always ask you for help if I need it (I will). The plane will (hopefully) look like this:

a.png

Also, I would like to say that since English isn't my first language, maybe you can see some mistakes in the post, sorry for that :(.
I'm going to start building it tomorrow afternoon (around 16 hours after I posted this). I'll see you then!

PD: This is the manual the kit included, in case someone wants to see it.
 

TooJung2Die

Well-known member
#9
I've just started building it, but after glueing the pieces, the waxpaper gets glued to the pieces as well. Is that normal?
That'll happen. It'll sand right off. Be a little less generous with the CA glue. Like Rockyboy said, it doesn't take much. Use just enough to tack the pieces together and then go back and apply more after it's lifted off the waxed paper.
 

MarioGdV

Active member
#10
Sorry for not answering, I had to go to do a few things. But good news, I've almost finished the fuselage. I just have to glue the formers to the left panel.

1555103640425651139616.jpg

That'll happen. It'll sand right off. Be a little less generous with the CA glue. Like Rockyboy said, it doesn't take much. Use just enough to tack the pieces together and then go back and apply more after it's lifted off the waxed paper.
Thank you, I will try to use less glue, but it's hard with my technique. I need to buy glue tips, as @rockyboy says.
 

MarioGdV

Active member
#14
I installed the 3x3mm bars. It's not 3x3 at all, more like 2x3 or 3x4. However, the holes in the formers have the same size, so it fits correctly, but I needed to make some of them bigger to fit the bars.

1555156155659167181663.jpg

You can see that in the right panel, the bar doesn't fit at all, but it still works.

15551563415931085435449.jpg

These bars were a bit more complicated to glue. I think I should have use warm water to make them more flexible, before I glued them in the fuselage.

I also installed the servos. The kit includes everything, I just needed 2 servos and the servo arms. Now I need to put this former here, but it doesn't bend too much. I'll use the water like I said before.

1555156712189299195592.jpg
1555156758111151086064.jpg

In this part, the pieces didn't join at all, so I decided to put small pieces of wood and use sandpaper to make it look good:

15551569311321552399039.jpg
 
#17
Bending that piece was harder than I thought. It broke in half several times, so I decided to glue the 2 halfs in the plane, and then use sandpaper to make it look as one single piece:
View attachment 128808

Should I install the motor and the ESC now?
I personally always wait until I finish building the plane (minus painting) to install electronics, unless the design won't let me access the compartments after the plane is built.
 

MarioGdV

Active member
#18
Now I have to make the bottom part, but I'm going to wait until I install the motor. Meanwhile, I've been making the wings. I don't know what to do here. The pieces are W1, W2... I guess W is for Wings. But there's also some thin pieces that are called "WM". I don't know what does it mean but it look a bit useless. For example, this one, WM5, should be installed here:

1555178575946216587550.jpg

The WM5 formers are those two little pieces, and they should be connected to the former W3-1there, but they don't fit because they're too big:

1555178801020797300447.jpg
I think it's a mistake made by the one who designed this. In the photos of the instructions, plane doesn't have the WM pieces (not the small ones). Should I use them?

Edit: I think I figured it out. The WM5 pieces have to be above the W3-1. That's why there's a small space in the top of them. But now I have another question. Where do I put this ones?

15551795726531142856507.jpg

Instead of WM5, they have WM7. I don't know what to do.
 
Last edited:

Joker 53150

Mmmmmmm, balsa.
Mentor
#19
Bending that piece was harder than I thought. It broke in half several times, so I decided to glue the 2 halfs in the plane, and then use sandpaper to make it look as one single piece:
It's too late now, but you can also soak the balsa in Windex for a while. The amonia helps relax the wood so it can bend more without breaking. Once it's curved to shape on the fuselage you can secure it with rubberbands, painter's tape, etc. and set it aside to dry for a day. After it's dry you'll find it hold the shape without the bands or tape fairly well.

You're moving along quickly, good work!
 

MarioGdV

Active member
#20
It's too late now, but you can also soak the balsa in Windex for a while. The amonia helps relax the wood so it can bend more without breaking. Once it's curved to shape on the fuselage you can secure it with rubberbands, painter's tape, etc. and set it aside to dry for a day. After it's dry you'll find it hold the shape without the bands or tape fairly well.

You're moving along quickly, good work!
Thank you! I didn't know I could do that. It's a bit late, but next time I will do what you said.