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Old Oct 10, 2012, 11:44 AM
Wanted for breaking OHM's law
Dennis Sumner's Avatar
United States, MI, Canton
Joined Sep 2002
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...reading along and see you are from Ketchikan Alaska...we were just there in August on the second week of our Alaska vacation. Gotta love the Arctic Bar and burgers from Burger Queen.....

Now back to our regularly scheduled build thread....

I'll be watching your build, love Cubs.

Denny
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Old Oct 10, 2012, 05:42 PM
Retired and Lovin' it!
United States, KY, Sturgis
Joined Jul 2007
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Brian, I looked a little harder for Tritle floats. See http://www.patscustom-models.com/shortkit4.html.

Also thought you might like this scheme. Not yellow and on floats!
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Old Oct 11, 2012, 08:23 AM
Cut it twice, still too short
dglo's Avatar
Bay City, MI
Joined Oct 2007
647 Posts
Nice work Brian. Are you still liking the magnets? I've thought about switching but I know at some point I'd be trying to stick a pin through the steel plate. I've used the hinge points and I like them, but only in larger planes. I'd use CA hinges but you only need a small one, maybe a 1/4" x 1/2". I made a tool for cutting the slots from a small chisel point xacto blade and glued a piece of sandpaper to one side. You just wiggle and push until through the balsa, and the sandpaper lets you size the slot to your liking. This would be a very cool plane on floats, but you might want a little more power than the stock setup provides. I made a set of skis for mine and they work great, almost makes me look forward to the snow.

Doug
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Old Oct 15, 2012, 10:31 PM
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United States, AK, Ketchikan
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It doesn't look like I've made a lot of progress over the past few days, because a lot of time was spent trimming and sanding the wing to shape. I ran into my first "Oops" moment when I was installing the aluminum strut mounting tubes. I was using some music wire to keep them aligned, and accidentally got a bit of glue in one of the tubes, which promptly became stuck. I tried working it out, but ended up tearing out the balsa around where I had tied and glued it in place. So I just cut out the broken section and spliced in a new chunk of wood and re-installed a new piece of tubing.

I also managed to get all the control surfaces hinged and sanded.

Next I'll solder the landing gear together. Suggestions on a way to mount it so it can be removed easily? I still need to make the cabin door, but beyond that there's not a left for me to do until I receive the hardware. I ordered a motor and ESC yesterday, but still need to order pushrods and control cable and covering, wheels, etc. That means I'll probably get started on my Jim Young Waco over the next week too, so look out for the build thread on that.
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Old Oct 15, 2012, 10:40 PM
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United States, AK, Ketchikan
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dglo: Yep, the magnets have worked very well.
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Old Oct 19, 2012, 02:38 AM
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United States, AK, Ketchikan
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Just a small update. I have a few pictures but I'll post them when I have more to show. I managed to solder together the landing gear wire. I'm not very good at soldering, so I used some copper wire wrap to help hold things together. The soldering isn't pretty but it'll do and I think I should be able to hide it when I add some wood bits to finish it off. I also glued is some small plywood hard points to the fuselage for mounting the gear, though I don't have the plastic gear mounts I thought I had so I guess those will be added to my hardware order. I had thought about soldering some metal stubs to the music wire to screw through, but I don't trust my soldering skills to make something that would hold.

More later.
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Old Oct 21, 2012, 11:53 PM
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I got a little more done this weekend, mostly getting the motor mounted, and a bit more sanding. I did manage to get most of the hardware and accessories ordered that I'll need to finish the plane, so hopefully in the next week I'll be able to get a lot more done that can be seen.

It's time to think about a color scheme. I would like to do a silver and some-other-color scheme, so I ordered some silver CoverRite CoverLite as a base, then I'll pain most of the airframe with some silver or other metal colored paint, then the 2nd color. Leaning towards green, but maybe a dark blue. I've been looking for inspiration online, but haven't seen too many Super Cubs with silver as the main color, so if anyone can be of help here, that would be great. I'll probably just make up something on my own, or find a white example then just replace the white with silver.
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Old Oct 28, 2012, 03:28 AM
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I thought I should at least do some sort of update since I haven't posted any pics in a little while. Progress I've made since the last post:

The cowl has been trimmed and fitted. The mounting points are some 1/4" basswood I had. I still need to make and fit the extra details for the cowl that weren't molded in.

The landing gear has been assembled. Just going per the plans right now. Eventually I may try to fabricate a gear with working suspension. The open part of the gear was filled with balsa, then faced fore and aft with balsa strips.

The door has been assembled. I had to re-do the upper door as it didn't fit right when built to the same size as the plan. Now to figure out a good way of hinging it (probably using covering material like Pat did) and also a way to secure it while in flight. I'm thinking the smallest rare earth magnet I can find and a washer. I'll probably glue in a small balsa stop around the frame. I'm also thinking about ways I could make a latch, but at this scale it's probably not worth it.

The struts have been started. Now I need to figure out the easiest way of fitting them since I don't have the handy jig that Pat uses.

I received my box of goodies from Tower Hobbies today, so I also mounted the wheels. Since the wire gear is 1/16" wire and the wheel holes say they are 1/8" (I think they're bigger), I cut some bushings out of 3/32" and 1/8" brass tubing to increase the axle size. It works pretty well but there is some slop even on the 1/8" tube which is why I think the holes are over sized. I need to think about making some hub caps like the real super cub has.

I ordered both a wood prop and a couple plastic props. I think the wood looks pretty nice, though the hole is a hair to big for the shaft included with the motor. I think I may be able to find some brass tubing to make an adapter out of. I also ordered a spinner, but the collet is too small for the motor shaft, and the prop is too big for the spinner, so I guess I need to figure out something else here as well. Though with the prop nut that came with the motor, it really doesn't look too bad.

I'm at work the next couple days, but over my next weekend, I'm hoping to get the struts installed so I can take a final "in the bones" photo, then I'll start the covering process and install the rest of the electronics.
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Old Oct 28, 2012, 07:06 AM
Cut it twice, still too short
dglo's Avatar
Bay City, MI
Joined Oct 2007
647 Posts
Nice work. On the issue of the door latch, I made mine the same way, using a tiny round magnet on a small door stop with a small section of steel wire glued to the door. I kept landing with the door popped open and had to add another magnet, I think there was just enough air pressure entering the fuse to blow the door open. I also put a small magnet in the bottom of the wing to hold the door up, making battery changes easier. Pat said cubs were often flown with the door open anyway.
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Old Oct 28, 2012, 09:15 PM
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In preparation for covering, I've been reading through posts on covering with Litespan/Coverlite. Found a couple posts from last year stating that the silver shrinks even less than the other colors. I've already been worried about the dreaded fillet on the tail, now I'm wondering if I messed up buying 6 packets of silver instead of plain white. Guess I'll find out in a few days...
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Old Oct 30, 2012, 04:06 PM
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Working on the wing struts now, and I'm not clear on the intended way of attaching the jury struts to the lift struts. I'm assuming I just glue them directly, though I had in mind that I could glue on some short pieces of aluminum tubing that the jury struts could sit in, so they would fold up while the plane is disassembled.
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Old Oct 30, 2012, 05:26 PM
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United States, TX
Joined Jun 2011
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I am sure there are different methods for setting washout, but I have always waited until after the wing is covered before setting washout because heat shrink coverings can sometimes create a warp. I then use the covering to hold the washout.

The way I measure it is by attaching a long straight stick of balsa to each wingtip at the same place on each wing, using a rubber band. The bottom of the airfoil is straight, so I have the stick against that with the rubber band up over the top of the wing to hold it.
Then I mark a location some distance from the leading edge, on the stick, like 1 foot. Then prop up the plane nice and level (I use model car boxes), and compare measurements from the leading edge up off the level support surface, and then at the 1 foot point. Then I use my iron to warp the wings until I get the washout I want.

Only concern here is, if I'm out on a really hot day, I'll bet the sun would change my washout settings. What other methods are used here?
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Old Oct 30, 2012, 06:15 PM
Neophyte hacker
portablevcb's Avatar
Albuquerque, NM USA
Joined Sep 2003
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I build in washout if I feel I need it. If the structure is not strong enough to hold it then I put in cross bracing in the wing rib bays to fix it in place. That way I don't have to worry about loose covering affecting the flying ability of the plane.

But, of my last 9 builds only two had washout, and it was designed into the structure, ie, the ribs and spars set the washout, no twisting involved.

charlie
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Old Oct 30, 2012, 07:00 PM
Cut it twice, still too short
dglo's Avatar
Bay City, MI
Joined Oct 2007
647 Posts
Someone please tell me if I'm wrong here, but I think the main reason for washout is to make the plane less likely to tip stall. Since most of Pat's designs are difficult to make stall even when trying to, washout could be less critical?
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Old Oct 30, 2012, 07:26 PM
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United States, TX
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My understanding is that when you lose lift over the main wing, because of inadequate airspeed and too high of an AOA, the wingtips with washout will have just a little bit of a negative AOA relative to the rest of the wing and will therefore stall a little later.

This provides a little more transition into a stall condition instead of the sudden snap and then you're not flying anymore. Makes it a little more predictable. I think this is more important with sailplanes that have very high aspect ratio wings.

At least that's how I understand it.
It gets more complicated than that in a hurry, and if there's any Aeronautical Engineers here, we might find out. Different airfoils and different shaped wings react differently. For example, the tapered wing of a Spitfire acts like washout, so you don't have to build that in...(I think I read that once).
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