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Piper Cub J-3 Build Log

TooJung2Die

Well-known member
#42
I used this diagram as my guide, it came with my covering film...
Applying covering film is one of my weakest skills. That diagram is great because it shows the general rules but we learn as we go.

A heat gun is indispensable especially when covering compound curves like wingtips. One of the biggest discoveries I made was that covering film can stretch as well as shrink. A heat gun makes stretching the film over wingtips much easier than doing it with an iron. I put a work glove on my left hand and the heat gun set on medium-low in my right hand. Leave lots of film to overhang so you can grab it. Heat and pull until the wrinkles you are working on disappear. If there's a wrinkle that won't go away by shrinking with the iron, use the heat gun and stretch out the wrinkle. Lastly, don't trim the overhang of the film until after all the wrinkles have been shrunk out or pulled out.

I had all but one panel on the SE5A wings covered. They looked okay, a few wrinkles. As good as I've ever done. On the last top wing panel I used the iron to tack down and switched to the heat gun to shrink and stretch. It came out so much better I stripped off all the previously covered panels and did them over. Eureka! :)
 

mayan

Well-known member
#43
Applying covering film is one of my weakest skills. That diagram is great because it shows the general rules but we learn as we go.

A heat gun is indispensable especially when covering compound curves like wingtips. One of the biggest discoveries I made was that covering film can stretch as well as shrink. A heat gun makes stretching the film over wingtips much easier than doing it with an iron. I put a work glove on my left hand and the heat gun set on medium-low in my right hand. Leave lots of film to overhang so you can grab it. Heat and pull until the wrinkles you are working on disappear. If there's a wrinkle that won't go away by shrinking with the iron, use the heat gun and stretch out the wrinkle. Lastly, don't trim the overhang of the film until after all the wrinkles have been shrunk out or pulled out.

I had all but one panel on the SE5A wings covered. They looked okay, a few wrinkles. As good as I've ever done. On the last top wing panel I used the iron to tack down and switched to the heat gun to shrink and stretch. It came out so much better I stripped off all the previously covered panels and did them over. Eureka! :)
Great tip!
 

MarioGdV

Active member
#44
I'm still covering pieces. I finished the wings, the ailerons, the vertical stabilizer and the rudder (and I'm finishing the horizontal stabilizer):

IMG_20190419_214457828.jpg

Also, I have a question. The motor is too small and I can't place the prop with the cowl installed. How can I install the motor so the cowl doesn't block it? Should a thick piece of wood glued to the nose work?
 

CarolineTyler

Well-known member
#45
I'm still covering pieces. I finished the wings, the ailerons, the vertical stabilizer and the rudder (and I'm finishing the horizontal stabilizer):

View attachment 129452

Also, I have a question. The motor is too small and I can't place the prop with the cowl installed. How can I install the motor so the cowl doesn't block it? Should a thick piece of wood glued to the nose work?
Usually you use a stand off to add a space behind the motor.
Google motor stand offs for more details...
 

MarioGdV

Active member
#48
Hi! I'm a bit busy these days (again), sorry for that :( . Maybe I can do something in the weekend, but I have a few exams next week.
I've installed the ailerons and connected them to the servos. I used the hinges that the kit included instead of the ones I bought because they allowed me to install the ailerons closer to the wings. I also connected everything to the receiver and I glued the bottom of the fuselage. Before I cover it, I want to refill the empty spaces between the pieces, so the covering looks better. I painted the motor cowl with spray, but in the inside. In that way, the outside looks cleaner. It needed 2 capes of paint, and maybe I'll paint it again:

IMG-20190421-WA0046.jpeg

Also, about the motor, I think I will use a 3D-printed platform between the motor mount and the firewall of the fuselage. The diameter is the same size of the motor, and in the middle there's a hole that I don't really need, but it will help me for the installing. The motor without the platform isn't big enough to install the propeller, but it only needs 4cm to get the shaft/axis out of the cowl. I have long screws and the piece is not really big, so I think it will work:

WEFec.png

This is how it looks now (the photo was taken before I installed the bottom of the fuselage). The tail is not glued yet. I'll wait until I cover the fuselage:
IMG_20190423_154528961 (1).jpg
 
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MarioGdV

Active member
#51
Thanks! I like how it looks, but if you look closer, it has a few scratches, specially in the wingtips. I removed most of them by heating them up, but it isn't perfect at all. Anyways, I'm happy with the results.
 

TooJung2Die

Well-known member
#52
I like how it looks, but if you look closer, it has a few scratches, specially in the wingtips.
Scratches? Is your covering iron bare? They make sock covers for covering irons. The purpose is to prevent scratching the covering. You can buy one or make one from a cotton sock. Here is one made from the toe of a cotton sock and some cotton string.

IMG_0959.jpg

jon
 

MarioGdV

Active member
#55
Scratches? Is your covering iron bare? They make sock covers for covering irons. The purpose is to prevent scratching the covering. You can buy one or make one from a cotton sock. Here is one made from the toe of a cotton sock and some cotton string.

View attachment 130113

jon

Sorry, I'm not English and sometimes I use wrong words. I wanted to say wrinkles (or that's what the translator says), there are a few of them in the wings, specially in the winglets:

15570088619371566051632.jpg

I tried to heat it up more, but they don't disappear.
 

MarioGdV

Active member
#59
I've been really busy these days, but today I installed the tail section and the tail wheel.

15582168623641848570425.jpg

I've almost finished it. Next step is installing the metal bars to connect the fuselage and the wings, the windshield of the cabin, the motor and those 2 black pieces to the motor cowl. I can't wait to see it finished!

Also, the covering of the elevator looks a bit worse than before, it seems that it needs to shrink again:

15582171397531562136679.jpg

Do I have to use the covering iron again?
 

TooJung2Die

Well-known member
#60
Also, the covering of the elevator looks a bit worse than before, it seems that it needs to shrink again:
Do you have a heat gun? You'll find some spots where an iron doesn't shrink the film but the iron pressure stretches it instead. I find a heat gun works better. It spreads the heat over a wider area without pushing on the film. You have to be careful with a heat gun. Set it to medium-low heat. A bit too close or a bit too long in one spot and the film melts. It took some practice but I find a heat gun a better tool than an iron on some difficult to cover areas.