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Piper Cub J-3 Build Log

Joker 53150

Mmmmmmm, balsa.
Mentor
#22
Sandpaper alone is going to create a LOT of dust. A balsa planer will shave excess wood quickly and then you fine tune it with the sandpaper. Much less mess that way, too.
 

rockyboy

Skill Collector
Mentor
#23
If you go the sandpaper route, stick a long piece of sandpaper (like 8 or 12 inches long) to a flat board with tape, and then do your sanding with the long side of the board going the long way down the leading edge. This will help you keep it the same shape all the way down, and not have an extra wavy leading edge! :D If you don't have a board handy, a carpenters level works great too - I've got sandpaper to stuck to a couple of those in my shop - and they stay straight too :D
 

TooJung2Die

Well-known member
#24
Those WM pieces look like rib caps. They go on top of the ribs making a wider area for the covering to sit on. Not certain in this airplane though.
 

MarioGdV

Active member
#25
I made it! (They don't look as good as it should, though)

15552647556801646070240.jpg

I used both sandpaper and this tool (I don't know how it is called in English), and it worked fine. The first wing looks a bit worse than the second one because it took me a while to get used to the tool:

1555264846283492959657.jpg

Now it's time to clean this up, and then I'll make the ailerons.

Also, I discovered how the WM pieces work. As @TooJung2Die said, they have to be placed on the top and the bottom of the wing ribs. Thank you!
 

MarioGdV

Active member
#29
Today I was a bit busy, so I couldn't do that much. But I covered a few parts for the first time! They don't look as bad as I thought.

15553582101291082216765.jpg
(I'm using Oracover)
I'm also a bit scared for the wings. Since they have parts that are "empty", I made pieces with holes so I could practice the covering. The problem is that the covering film above those holes isn't enough tense. If I touch it with my finger, the film moves a bit. I saw in the internet that I had to use more temperature so the Oracover gets smaller, but I think it didn't work, or maybe I'm doing it wrong. I'm using a covering iron without thermometer, so I can't see the temperature. Any ideas?
 

rockyboy

Skill Collector
Mentor
#31
Covering is looking great! And yes, you're on the right track with using higher temperature to get it to shrink up. I sometimes use an infrared thermometer to figure out how hot the iron is, and then read the product literature to see what the shrinking temperature is. Mostly I just crank the iron all the way up and start by hovering the iron over the open space areas and then if that doesn't make it start shrinking, gently and lightly run the iron over it in circles, never letting it stop too long in any one place. It is a bit of a 'learn by feeling / doing it" kind of activity, and when using a new roll of covering it's always best to try it out on a test piece, cause every covering brand acts differently when they start to shrink and do so at different temperatures. Sometimes they go really fast, other times they get a little saggy, and then tighten up when the cool down.
 

CarolineTyler

Well-known member
#32
Everything that @rockyboy says basically. My first go at using covering film was a success but please don't look too closely :)
The first wing panel I did, which has a lot of exposed ribs is not nearly as good as the second, so it's definitely a learn as you do thing. I did a couple of test bits beforehand to determine a good glue activation temperature and the higher shrink one, my iron is a basic one with just a manual dial and L / M / H areas marked. The box it came in gave approximate temperatures for these areas.
The cotton sock on the iron made it a simple thing to keep the iron moving freely.
Oh! and work your way up a piece so covering overlaps are held down by air movement and sealed from wet/fuel (should you build a gasser).
 

MarioGdV

Active member
#35
Thank you all for the help! My iron also has a temperature regulator (with L/M/H areas, like the one that Caroline has), and after testing the covering in other pieces, I think I know approximately the temperatures. When it's between Low and Medium, the Oracover starts to get sticked to the piece, and if I increase the temperature, it starts to shrink. At maximum temperature, the colour changes for a few seconds and it gets really tight. I think I'm ready to start covering the plane. Also, I finished al the pieces, should I cover the ailerons (and the elevator and rudder) before I install them?
 

CarolineTyler

Well-known member
#36
Thank you all for the help! My iron also has a temperature regulator (with L/M/H areas, like the one that Caroline has), and after testing the covering in other pieces, I think I know approximately the temperatures. When it's between Low and Medium, the Oracover starts to get sticked to the piece, and if I increase the temperature, it starts to shrink. At maximum temperature, the colour changes for a few seconds and it gets really tight. I think I'm ready to start covering the plane. Also, I finished al the pieces, should I cover the ailerons (and the elevator and rudder) before I install them?
Yes, cover them first otherwise it will be a right fiddle to wrap the covering around. - speaks from a painful experience ;)