RE: Sig 1/4scale C/W Cub build
 

That's one nice looking Cub! Your pictures are great Anthony you must have a really nice camera...Did he mention what he paid for the Cub?

RE: Sig 1/4scale C/W Cub build
 

He didn't say, he bought it used with the engine and servo's in the plane. I checked and new ones are $2k without engine/radio. He said the deal was too good to pass up but I am sure it was alot of $$$$.

My camera is a Nikon D3000 with a 200mm zoom lens. It does a pretty good job.
Later!!
Anthony

RE: Sig 1/4scale C/W Cub build
 

How many of you would attempt this!</p>

RE: Sig 1/4scale C/W Cub build
 

It's scary enough starting one on the ground:D The 1st time I hand propped a 1:1 J-3 It was a bit intimidating.

RE: Sig 1/4scale C/W Cub build
 

Good to see you nickname is WacoNut and not Lefty!

SunDevilPilot
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RE: Sig 1/4scale C/W Cub build
 

Yeah, right! You're not trying to make fun of me now are you VJ! http://www.rcuniverse.com/forum/js/f...bout_smile.gif

RE: Sig 1/4scale C/W Cub build
 

I got the firewall glued to the nosepieces. Having sanded the 5 degree angle into the sides of the firewall helped tremendously getting everything done easily. I started by epoxying the first side of the nosepiece to the firewall. I checked the angle with my protractor to make sure the angle was correct. I then epoxyed the second nosepiece side to the firewall (pictured). I checked the angle again with a protractor. I used the squares just to hold everything in place while everything dried. When I went to dry fit the nose section to the fuse everything fit perfectly which I was very happy about. I did use a couple of t-pins just to make sure nothing slipped while the epoxy was drying.

Pic 1: gluing the 2nd nose piece to the firewall
Pic 2: gluing the 2nd nose piece to the firewall, another angle
Pic 3: nosepiece pinned to the fuse with the epoxy drying (note the ingenious weight on the firewall to ensure a good tight joint)

RE: Sig 1/4scale C/W Cub build
 

What is the diameter of these tires?

RE: Sig 1/4scale C/W Cub build
 

They are 4.25" Tires.

SunDevilPilot
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RE: Sig 1/4scale C/W Cub build
 

Thank you

RE: Sig 1/4scale C/W Cub build
 

So just as I thought the next step that I was a little concerned about was done I discovered I'd made my first screw up. I got the music wire supports epoxyed into place, both the ones I added down the window supports and the stock ones that go from the middle of F5 down to the nosepieces on each side. Once everything dried I started looking at the back to think about starting on the turtledeck when I discovered my screw-up. It was due to the fuse modfication I am doing so I can't be mad at anyone but myself for not thinking about it first.

The music wire that passes through F5 extends into the path that the ply spar that will go through my 2 root ribs/cabin top. The spar needs to stay 1 piece as it will fit into the pockets in the wings to set the dihedral. Now I have to figure how to fix this. The bottoms of the music wires are set so the I'd have to rebuild the whole firewall and nosepiece to get the wire out.

I'm thinking about doing something similar to VincentJ's build and soldering a washer around the music wires flush with the back of F5 then using the cutoff wheel on my dremel to cut off the wire that extends beyond the washer. I think there might be just enough space between the back of F5 and where the ply spar will pass to make this work.

Any other ideas?

RE: Sig 1/4scale C/W Cub build
 

Looking good. I will say adding the wire to the cabin area ads a great amount of strength to the cabin area. I have had several hard hits over the years as I would stall it.

RE: Sig 1/4scale C/W Cub build
 

Hmmm... I see your predicament. Your idea sound the best to me. Cut the wires flush with the back of F5, then inlay and solder a washer to the back side. It seems to me that most of the load is going to be on the outside wires anyway. HOWEVER, I am no expert at this, still somewhat of a newbie. But again, your idea is the best I've read so far... :eek:

Take care and keep going!
David

RE: Sig 1/4scale C/W Cub build
 

I would cut the ply main spar in half and make a space for the wires in the middle. Once glued in place, to the former and upper cabin ribs, I would add a one piece ply doubler, maybe 1/8' ply, to the backside of the main spar that has a hole in the middle for the support wires. Remember, the struts on this plane are 100% functional so the only force on the ply joiner in flight is straight up and down at the innermost edge (Like an anti-rotation pin). More of a sheering force exerted straight up and down at the ply spar at the fuselages edge. There is no force trying to bend the joiner and break it. There may be a slight amount of downward bending pressure when the wings are being installed onto the plane prior to the struts being attached but a 1/8" doubler can support that.

Don't make the job too difficult trying to keep the plywood in one piece.

My friend's cub doesn't even have a plywood joiner, just a front and rear anti-rotation pin.

Just my thinking,

SunDevilPilot
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RE: Sig 1/4scale C/W Cub build
 

Proof of concept... Here is my Sig 1/5th Scale Cub many years ago in the construction phase. When the manual called the builder to cut the aluminum wing tube in half I was a little shocked... Why would I cut it in half, doesn't that defeat the purpose? But remember, on a plane with struts the main force the fuselage sees is compression as the wing are picking up the plane and trying to fold upwards in the process. The force causes compression on the fuselage. Because of the struts the lift of the wings will try and pull the fuselage apart at the bottom and smash it together at the top. In the case of the cub the whole fuselage acts like the main spar spreading the load and making it extremely strong. You would be hard pressed to fold the wings of a cub unless you had strut failure, in that case no tiny ply spar will keep the 105" wings from folding.

Here are a few photos. Note, the wing tubes do not connect and are divided by the roof window. The tubes just keep the wings in place.

RE: Sig 1/4scale C/W Cub build
 

Thanks for the reply SDP. I didn't think about it like that. I still need to attach the upper ends of the wires to the F5 header so I'm going to see if I have enough in the gap to make it work the wayI was initally thinking. If it doesn't seem like it will work well I'll be cutting the spar as you suggested.

RE: Sig 1/4scale C/W Cub build
 

For every problem there is a solution. Good call SDP....

RE: Sig 1/4scale C/W Cub build
 

Yep! Uh-huh, told ya! http://www.rcuniverse.com/forum/js/f...sn/biggrin.gif SDP's got the experience I lack. That's why I like this forum thing so much, there's a lot of good people out there with brilliant ideas. You learn a lot here and also learn how much you really don't know (speaking for myself anyway). Thanks SDP!

RE: Sig 1/4scale C/W Cub build
 

I got my problem with the ends of the cabin reinforcement wires fixed this weekend. Ended up not to be very difficult and I think the fix remains quite strong. I dremeled out the opening in a washer to be just big enough to fit both 5/16" music wires side-by-side. I then tried to solder it but even using a torch I didn't get the solder to flow as well as I would have liked it too. I might have been a little hesitant with a torch around the wood to get it hot enough though. I ended up adding some JB weld to fill in the few spots I didn't get the solder in and a little between the bottom of the washer and the wood. I once everything had cured I took my dremel with a cut-off wheel and cut everything off flush with the washer. I tugged on the wires pretty good and felt no give. Between these wires and the ones in the front window supports I think the front cabin is strong as a tank. There is just enough gap between F5 and the ply spar for the washer to fit.

Pic 1: wires ground flush to the washer
Pic 2: another view
Pic 3: Front of fuse with the spar in place
Pic 4: Rear of fuse with spar in face
Pic 5: just enough gap for the washer to fit

RE: Sig 1/4scale C/W Cub build
 

Looks good to me!

RE: Sig 1/4scale C/W Cub build
 

Neddy, Looks like a great job so far. I have a question, now that you have shortened the firewall what and what size fuel tank will you use and where will it be located? I am thinking about the same mod, but I am not sure of fuel tanks.

RE: Sig 1/4scale C/W Cub build
 

Ace, What size are your wing tubes and where did you buy? Also, the Sub D connectors; Radio Shack? or ?

RE: Sig 1/4scale C/W Cub build
 

I haven't really thought much about the fuel tank yet. I'm not planning on doing an interior so it doesn't bother me much if it sticks out from under the dash a little. I've got to go to the LHS sometime in the next week or so and was planning on picking up a tank then. Here are a few pics of the DLE30 with the bisson pitts muffler mocked up. I didn't shorten the ply doublers that go over the nose piece because there's not very much overlap at all between the cowl and the new firewall position and I'll need something to attach the cowl to.

RE: Sig 1/4scale C/W Cub build
 

I've gotten a little more work done on the Cub. I got the top stringers put on the turtle deck. Wasn't to hard to soak the top-side stringers and get them bent to the proper curve. I'm thinking about adding small ply triangle gussetts between the formers and the stringers with the curves on the end because the tiny glue joints between the formers and the stringers don't seem like they'll take much at all to break if something happens to them much more than a light bump.

RE: Sig 1/4scale C/W Cub build
 

I tackled the right side door today also. I did a little bit of a hack job cutting out the door out of the lite ply back when I was building the fuse sides. I had to do some sanding and add a wedge of wood to the fuse side to bring it back to the correct shape. The lite ply door cut out was trash so I had to build a new one. I traced the corrected door opening and cut it out from a piece of 1/8" birch ply. With just a little careful sanding it was a perfect fit. I cut out a lightening hole from the center of the door then added a 5/16" balsa frame. It fits great now. I'm planning on using tiny rare earth magnets in the frame and door sill to keep the door shut.

I've also added the cabin window braces which still need to be sanded flush to the fuse side. I'm excited because the fuse is nearing completion. There are still a number of things that I'll have to do to it but I'll be able to move on to the tail feathers and wings in the near future.

Pic 1: front of the new door
Pic 2: back of the new door
Pic 3: The small fix I had to do to the fuse side/door opening
Pic 4: New door in place with all the cabin window supports in place
Pic 5: The plane as it is today