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Sig 1/6th J3 Cub

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Old 01-05-2004, 01:32 AM
  #1  
tubig
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Default Sig 1/6th J3 Cub

working on a 1/6th scale Sig Cub among other things. Sig calls this a "Craftsman kit" probably because it's about as close to scratchbuilding as you can get in kit form. very similar to the Marutaka kits in that you get a lot of sticks and sheets which you put together by trial and error fitting and shaping....which is fine with me. this kit takes a lot of time and patience and makes a good long winter build if you like that. to give you some idea how old this design is, the copyright date on the plans is 1975.

a pic of the fin and rudder. still needs shaping of leading and trailing edges and hinging.
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Old 01-05-2004, 11:02 AM
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Steve
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Default RE: Sig 1/6th J3 Cub

Though they are a builders kit, they build very light and fly very well. Once you build a kit like this, other kits are easy to build.

Steve
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Old 01-05-2004, 12:35 PM
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Default RE: Sig 1/6th J3 Cub

Actually this kit is a lot older then the copyright 1970 on the plan. It was origionally a Berkley kit and was produced somewhere around 1958. Sig picked up the kit when it bought the assets of Berkley's business.
It was origionally designed to be able to be flown with rudder only then to 3 channels. I'm sure that the redesign in the 70's to incorporate ailerons and somewhat easier construction necessitated a new plan and a new copyright. Dennis
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Old 01-05-2004, 05:50 PM
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Default RE: Sig 1/6th J3 Cub

wow, i didn't realize this kit had so much history to it even though the construction techniques do seem old. so far it has been a fun build and has challenged me in certain techniques such as cutting angles to get a good fit with framing members. thanks for the info.
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Old 01-05-2004, 09:49 PM
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Default RE: Sig 1/6th J3 Cub

Before it was a Berkeley kit it was published by Chuck Hollinger in the Jan 1955 edition of American Modeler magazine.

By the way, the Berkeley kit called for a .15 to .19, and the engines available at the time in those sizes generally produced way less power than equivalent sizes do now.

No doubt Sig has modified the structure some, but I bet you could still fly one on a modern .15 if you kept it light.

Have fun with your piece of modeling history!

Jim
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Old 01-06-2004, 01:59 AM
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Default RE: Sig 1/6th J3 Cub

yes, i had originally planned on an OS26FS. but it looks like that would even take some modification to the firewall to give a good fit inside the cowl. as it turns out, i don't think i'll be flying this one as my wife has asked to let her hang it in her restuaurant.
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Old 01-06-2004, 08:30 PM
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Default RE: Sig 1/6th J3 Cub

so here is the horizontal stab and elevator. still needs hinging and shaping of the leading and trailing edges. getting the end of the inside trailing edge of the elevator rounded to fit well with the joining dowel was fun.
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Old 01-09-2004, 12:57 AM
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Default RE: Sig 1/6th J3 Cub

i've been able to work some on the wing. here is the right wing half. the kit called for a single servo with bellcranks to the ailerons. i chose to go with individual servos for each aileron. i've almost completed the compartment to hold the servo. you can see the triangular pieces i've used to hold the screws for the plywood servo cover. the piece of tape is just securing the string i'll use to run the servo leads to the center.
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Old 01-10-2004, 06:55 PM
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Default RE: Sig 1/6th J3 Cub

I finished building this kit, last Spring, for a friend in my club. He had started it circa 1980, and never had the motivation, skill or nerve to finish it. I got it with the wing framed up, and the fuselage just begun. It still took quite a while to finish up, but what a neat plane when it was done It's only been flown once during the Summer, and I wasn't even there

Do these pictures look familiar?
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Old 01-11-2004, 03:39 AM
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Default RE: Sig 1/6th J3 Cub

great pictures phlip! thanks for posting. i've downloaded them to my computer for future reference when it's time to put it all together.
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Old 01-18-2004, 12:27 PM
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Default RE: Sig 1/6th J3 Cub

i've managed to work some on the fuse. it takes a while to build this as, you can see, it's stick built. the most frustrating part is keeping the spruce stringers that form the cabin outline from breaking off. they are just end joined to the balsa sides and that doesn't provide a good glue joint. still, it has been an enjoyable build so far.
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Old 01-18-2004, 10:01 PM
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Default RE: Sig 1/6th J3 Cub

the most frustrating part is keeping the spruce stringers that form the cabin outline from breaking off.
Ah, yes I remember that frustration. It gets much sturdier when the plywood piece at the front top of the cabin is installed along with the music wire pieces. The music wire has to be wrapped and soldered, also. The landing gear is constructed the same way. That's a fun job. Hopefully, you've had some experience soldering.

Have you considered making the cabin door operable? It is a bit more work, but it adds even more scale-like realism.

Phil
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Old 01-19-2004, 05:26 AM
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Default RE: Sig 1/6th J3 Cub

phil, i think i have broken off each spruce stringer at least once now! the plywood piece and "rollcage" are next so hopefully that will help like you say. i have some limited experience at soldering and i have some friends who can help me if i goon that up.

as far as an operating door, i think i will give that a go. again, i don't think i'll be flying this one but an operating door will still look good.
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Old 01-19-2004, 06:34 AM
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Default RE: Sig 1/6th J3 Cub

It's a shame not to fly this one! Mine is five years old now. Had a Fox 35 on it, but it was too loud. Has a Saito 30 now which is just right.

Covered in yellow Solartex. HS 81 micro servos all around with pull pull on rudder and elevator. Weighs a little over 4 pounds. Slow flybys and touch and goes are about as good as it gets. Doesn't like wind though.

I added 1/32" shear webs to the wing spars. The wing struts are functional and must be used for flight.

I think this plane won the 1959 Nationals in Scale. It's one of my favorite planes.
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Old 01-19-2004, 08:45 AM
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Default RE: Sig 1/6th J3 Cub

fox35, yeah, i know. it's a shame not to fly it but the boss (who lets me enjoy this hobby ) says she wants it for her bar/restuarant. she had the ceiling painted to look like the sky with clouds and she thinks a plane would go pretty well with it. here's a photo showing what i mean. anyway, i had a feeling that the J3 would be a little touchy in wind, as you say, and where i fly it is almost always windy and a crosswind at that.
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Old 01-19-2004, 06:33 PM
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Default RE: Sig 1/6th J3 Cub

A yellow Cub would look great against that backround for sure. There is no sweeter looking Cub than this one.

Gotta make the boss happy though. Maybe if she changes the decor sometime you'll get to fly it. It does demand a calm day. No fun at all in the wind.

I fly mine sometimes at the local soccer field. With the Saito 30, it's quieter than a geared electric.
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Old 02-09-2004, 02:29 AM
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Default RE: Sig 1/6th J3 Cub

well, for anyone following this i'm sorry i haven't had much to post lately. i've been a little delayed by other things.

i'm up to adding the 1/8" music wire to the forward cabin area that supports the leading edge of the wing. this has caused more trouble for me than i expected. the wire is mostly prebent to fit; however, it still needs to be bent to follow the frame portion of the lower fuselage. it looks like i'm going to need some wire benders since i'm not having much luck with hammering it in a vise. i think you can see what i mean from the photos. you can also see how some of the fuselage frame is relieved to accept the wire. the wire on the right side of the photo is in place whereas the left side has yet to be done.
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Old 02-10-2004, 03:54 PM
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Default RE: Sig 1/6th J3 Cub

My instructions mention that the wires may need to be bent. My are not working either. You are on the right track, just bend them little by little until the wire mate properly with the structure.
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Old 02-11-2004, 08:20 PM
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Default RE: Sig 1/6th J3 Cub

after sitting back awhile i finally decided to just fill in the gap between the wire and fuse frame instead of trying to beat the wire into submission. it was much easier. here's what i have.
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Old 03-30-2004, 10:23 PM
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Default RE: Sig 1/6th J3 Cub

slowly back to work on the cubby after a long time off. i needed to shorten the nose by 5/8" to accomodate the OS30FS i plan on using. also, while i was at it, i incorporated the 3 degs. nose down thrust that is shown on the plans into the fuse structure vs. angling the engine bearer as the kit specifies. i also glued in the 1/4" balsa sheeting "fill" pieces into the nose. now time to apply the 3/32" skin to the forward fuse.
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Old 04-05-2004, 06:20 AM
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Default RE: Sig 1/6th J3 Cub

not much to add, just the front fuse sheeting.
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Old 04-05-2004, 06:45 AM
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Default RE: Sig 1/6th J3 Cub

Tubing,
Nice looking build on the Cub. I love to build and it took me 3 years of part time building to do mine. I used a OS 40 Surpass 4 stroke, standard Hitec servos and only one on the ailerons. The bellcranks were the worst part. Using two Hitec HS81 would have been a much better choice. I had to cut the firewall back about 1 1/2" to keep the nose of the cowl in the correct place. The plane ballanced fine this way. I also cut one bay out on each wing to give the plane more roll authority. Put two pilots in and she will fly this summer. Keep the pics coming.
JEB
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Old 04-05-2004, 08:09 PM
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Default RE: Sig 1/6th J3 Cub

jeb, how do you think it would fly with a .30FS? i'm thinking this kit was designed 30+ years ago and then called for a .19-.35 two stroker. with the advancement of engine technology maybe a .30FS will be sufficient and i won't have to cut up the front so much.
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Old 05-22-2004, 09:24 PM
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Default RE: Sig 1/6th J3 Cub

so i've added the sheeting to the forward fuse top and sides.

also, i've been working on the cockpit door. i cut the outline out of the sheeting and then reinforced around the edges with 1/8" hard balsa. i'm using regular pinned hinges for the door hinges. not too scale but it was what i had on hand. door top is just taped in position now.
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Old 05-22-2004, 09:44 PM
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Default RE: Sig 1/6th J3 Cub

i've added the fin and stab dowels. that was a real pain to get the dowels in place at the correct incidence and square to the fuse. the way this kit is set up, i'll have to cover the stab and fuse separately and then install the stab to the mounting dowels since there is a gap between the fuse and stab as per the full size. since the elevator is captured by the fin post i went ahead and covered it before putting it into position and then permanently installed the fin. the real potential problem here is getting the elevator hinges in neatly since the elevator is already in such close quarters with the stab. i've done a trial fitting of the hinges and it can be done even though it's not easy.
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