Hacker Piper J-3C Cub - Page 3 - RC Groups
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Jan 29, 2013, 07:36 PM
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"Orange propeller doesn't look great to be honest... "

Maybe not but a bit of paint will cure that, the rest of it, the bits you built, looks superb, there are a lot of Cubs but having flown a few Cub models and a full sized J-3 and loved them all, I can say with authority that there can never be too many Cubs!

Keep up the good work, you're doing a great job so far.
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Feb 01, 2013, 06:48 AM
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Build is on hold a few days as I'm prohibited from "working in dusty areas" (no balsa sanding for me!) due to a laser eye operation. I did the operation yesterday and I can already see like an eagle, so flying will involve a lot less guessing the position of my little planes from now on. I hope it makes me a better pilot, because now I've got one excuse less when something goes wrong.
Feb 01, 2013, 04:39 PM
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davidterrell80's Avatar
I'm pleased for your successful operation, and look forward to seeing your build progress!
Latest blog entry: Remembering Bob Hoover
Feb 02, 2013, 03:21 PM
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Edit: double post
Feb 02, 2013, 03:24 PM
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Unsurprisingly, I haven't been able to go a whole saturday at home without building some. I've kept to "clean" jobs like covering (wing supports and the top of the wing) and mounting the electronics in place.

Weight wise it looks like I'm doing quite well. I weighed the whole thing and came in at 85g. It's going to need another access hatch for battery access, some covering film, stickers and windows, but that's about it which means I'm pretty much guaranteed a weight of less than 90g when done. That weight does not include batteries which will add somewhere between 15-25g depending on what I fly with. I'll probably use turnigy 180/300mah 2S batteries as this is what I've got at home already.

I think I'm going to get a pretty good starting point for my center of gravity too. The wing is 10.8mm wide, the plans (free flight) dictate a center of gravity of 35mm from the leading edge (32% of the wing). My preliminary CoG (without ballast anywhere) seems to be at 30mm from the leading edge (27%). I think that might be usable for a first flight?
Feb 03, 2013, 04:06 AM
Slip the surly bonds...
Sopwith Mike's Avatar
I'd go for 27% for the first flight and move back as required: you can always trim it out if it's nose heavy, but tail heavy = crash in my (extensive) experience.

26 days to go till the end of the contest - good luck with the maiden!

Feb 04, 2013, 05:23 PM
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I've been quite bad at keeping myself from building. I've kept sanding to a minimum to go easy on my newly operated eyes.

I've done some insert-sheeting around the mid-section to keep battery wires from poking at the covering, don't think it added much weight. Had to trim the pieces to size with a knife instead of sanding to avoid dust which took some time.

The plane is almost completely covered now, and the internals and means of accessing them are all done.
Feb 05, 2013, 05:33 PM
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Allow me to present a newly built Cub so fresh off the assembly line, they haven't had time to add any registration number or decals to it yet!

Hacker Piper J-3C Cub RC Conversion (0 min 21 sec)

Weather here has been awful for flying small planes lately, I did actually fly my UMX Beast last Saturday for a while even though it was -5 C. The biggest problem was the snow which was of the old and hard kind, cratered completely by footsteps which left absolutely no smooth runways to land on. I'm not going to stress-maiden this plane, if the weather is bad it'll be grounded in favor of planes I'm less afraid to pulverize.
Feb 06, 2013, 06:07 AM
Slip the surly bonds...
Sopwith Mike's Avatar
Very nice indeed XeCutor. Our flying weather is as bad as yours (perhaps not so cold) but it looks as though Saturday might be possible,

Feb 07, 2013, 03:41 AM
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I have never in my life experienced something as frustrating as these water slide-on decals. I'd done one before, the dashboard in the cockpit, that went relatively smoothly. Pretty much all of the outside decals were a disaster, at least the larger ones. I spent the entire evening yesterday trying to get them on. They pretty much all broke into pieces, and when I lifted up the plane to put it on the scales this morning, all the decals I touched came unstuck or broke. AAAAAH!H!!H I managed to get some to stick better by using an extremely thin layer of glue stick, problem with that was that once in place, the decals would no longer slide around without being pulverized. I better get a few pictures taken so I can have a picture of the plane before all the decals fall off.

What's a good way to fabricate new ones that will be a bit more durable and stick better? It can't be the norm to have decals this frustrating, can it? It probably didn't help that I'm a newbie at applying these things, but even the last ones I put on after hard earned experience didn't really qualify as a great result.
Feb 07, 2013, 03:50 AM
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Oh, I forgot to mention what the scales showed with the plane completed. I realized I had forgot to weigh the wing-supports before which added a couple of unexpected grams. I therefore blew my expected 90g-battery-less-weight by a little bit. Flying weight with a 2S 180mah battery is 105g which is a little higher than I'd have liked it to be, but it's definitely going to be flyable at that weight. I'm hoping it'll be able to trot along slowly, but flight tests will have to show what kind of bird I've built.
Feb 07, 2013, 06:27 AM
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Eclipse_7's Avatar
Water slide decals can be very frustrating. I've had some that were just like yours, they tear and dont stick at all. I've also had some that work great. You can buy sheets of printable decal paper, but I've not had any first hand experience with them. There is also a thread detailing how to print decals onto tissue paper.

I built a 26" cub similar to yours but covered it in tissue. It was a scratch build so I had no included decals. I ended up painting on the registration numbers and lightening bolt. The cub on the tail is from a replacement decal sheet I found at the LHS (cant remember what model it was for).

I have the Hacker Decathlon in the box ready to be converted, so I have been following your thread. Very nice work you have been doing!
Feb 07, 2013, 06:54 AM
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I guess I might look into printable decal sheets. Tissue paper decals seem like they'd fit best onto something covered in tissue.

Lovely cub you have there by the way. Looks like gear stripped from some e-flite/parkzone plane? What does it weigh?
Feb 07, 2013, 07:09 AM
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Eclipse_7's Avatar
I built the landing gear to be functional, mostly out of .020 music wire and 1/16 aluminum tubing. It ended up being somewhat delicate, but it was fun to watch them in action.

My RTF weight was 93g. Here is the maiden flight.
Scratch built 26" J3 Cub (1 min 31 sec)
Feb 07, 2013, 10:23 AM
payne9999's Avatar
Originally Posted by XeCutor
I guess I might look into printable decal sheets. Tissue paper decals seem like they'd fit best onto something covered in tissue.

Lovely cub you have there by the way. Looks like gear stripped from some e-flite/parkzone plane? What does it weigh?
For small models the water-slide decal sheets work well. I like the vinyl ones myself but they are a little thick and heavy for such a small plane. Micro Models has decal paper (both white and clear) and there are many other suppliers as well.


Very nice, I am amazed at how well small models can fly. 100 grams seems to be about right for these planes. I am building a Super Cub now that is looking to be 110-120 grams. Can't wait to try it out.


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