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Author Topic: Piper Cub "1983" Build  (Read 769 times)
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vtdiy
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« on: December 14, 2018, 04:17:56 PM »

This is a Piper Cub By David Scigliano, "1983". I've been working on it for a few days already. Here is the stage I'm at today.... The fuselage structure is mostly done except for the landing gear and crosspieces. I might get that done tonight. I really like the construction of this model. The only difficult part I had (as a not very experienced stick and tissue modeler) was starting to put the two fuselage sides together. there's no formers, or bulkheads, just cross sticks so it was hard for me to get it glued initially and have it aligned properly. I'm sure there's smart ways to do this. But not knowing them, I got it done anyway.

To hollow out the upper and lower nose blocks, I made up a scorp out of an old disposable razor/s badn shaped blade, bent into a U shape and copper wired to an old paintbrush stick, then epoxied.

The fuselage weighs 5 grams now.

http://www.sredmond.com/Models/Piper/Fuselage-3.jpg
Piper Cub "1983" Build
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Yak 52
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« Reply #1 on: December 14, 2018, 04:50:11 PM »

Very nice work. I really liked my version of this model.

http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=10532.0

Flew beautifully off the board and eventually ended up as a floatplane Smiley

Jon
« Last Edit: December 14, 2018, 05:59:24 PM by Yak 52 » Logged
vtdiy
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« Reply #2 on: December 14, 2018, 07:58:11 PM »

Beautiful job you did, Jon! Mine is better seen at the present distance and soft focus, by comparison! I do have some bend in the lower longeron -- didn't know about wetting the top one, like you did. I'll remember that!

Also, my first worries about covering are now well multiplied by your experience!

I just learned from your thread that Scigs30 is the designer.  In your thread he said something about domestic tissue shrinking less, which is all I actually have, so I'm a little more hopeful.

Well, I'm afraid this thing might look pretty sad by the time I get through with it. I don't have any dope now, the few stick and tissue models I've done before were not doped (that means...2 of them vs. 1). I did iron the tissue before applying it back when I built those -- which kept it from warping, for the most part. The Pacific Ace Bostonian's wing I built, which was doped at the time did warp.

I was thinking of trying EzeDope on the Cub. I have had a bottle of that for a couple years unopened. Funny thing....I was just looking at an old thread by Peter Rake on RCG, about EzeDope experiments, and coincidentally, there is Scigs30 trying it out on a couple models! It seemed to work well for those. Beautiful covering jobs.

I am very glad to read your thread, Jon, because it tells me a lot abut what to expect -- I wonder if I should gusset the wing saddle area on the fuselage, like you did? Also, you mention what kind of rubber and how much to use -- that will really help to get me started trimming.

Don't know if you saw earlier but I didn't laminate my rudder,I soaked the edge piece and used a soldering iron a la Bradleys to hand steam in the curveby eye, and then I just pinned it down on the plan and added the framing. It actually went well, though, again your work is superb, by comparison. Anyway here it is off the building board before sanding:

http://www.sredmond.com/Models/Piper/Tail.jpg
Piper Cub "1983" Build
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Yak 52
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« Reply #3 on: December 15, 2018, 06:06:00 PM »

Thanks for the kind words - but kudos is really due to Scigs for a great little design.

I am very glad to read your thread, Jon, because it tells me a lot abut what to expect -- I wonder if I should gusset the wing saddle area on the fuselage, like you did?

It's a long time ago I'm afraid, but as far as I recall - I think if you pre-shrink the tissue you'd probably be alright without. I would definitely consider the diagonal piece and gusset in the nose area - there's a definite stress riser where the side frame meets the stiff balsa block. (See reply #18)

Jon
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vtdiy
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« Reply #4 on: December 15, 2018, 06:23:12 PM »

Thanks Yak52. I'll probably do that. I didn't have much time for modeling today -- insulating under an addition to the house, but I did get a little done on the horizontal stabilizer. I used the same soak and pre bend method with a soldering iron. I just realized that there's no way to get it into the fuselage without cutting the rudderpost at the back. I guess that's okay, and it won't be hard to put a small plug there afterwards.

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scigs30
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« Reply #5 on: December 16, 2018, 09:26:12 PM »

Looking good. For boxing up the fuselage, I show how I did it in my build.
http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=5018.0
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vtdiy
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« Reply #6 on: December 16, 2018, 09:47:46 PM »

Thank you kindly Scigs! I love your design -- it's a joy to build. I do wish I'd seen you thread first (and Yak52's) just because it's inspiring and I certainly would have boxed the fuselage up your way, instead of trying to put the tailpost together first and do it rightside up. Yours makes sense. I guess what threw me was the curve in the upper longerons, I didn't think I could lay that flat. But, duh, now I see you just laid the wing saddle flat!

Well, next build I'll remember. Small balsa stick building is still a learning experience for me.

I hope I can fly this indoors -- otherwise it's going to be a looong winter!

I'm up to 6 grams for fuselage and both tail surfaces so far, but no landing gear, prop, or wing yet. I hope I end up not too high above 14 grams. The covering is the most worrisome part for me in all ways.
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scigs30
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« Reply #7 on: December 19, 2018, 09:22:33 AM »

Oh yes covering.....If you look at my post you see the picture of me flying my Cub Bostonian when I was a kid, that is how long I have been covering.  If you go with Esaki like I did, you either have to pre shrink the tissue on an old picture frame or instead of dope use Eze Dope.  Now I know some builders are not a fan of Eze Dope but I can honestly say there are more advantages to using Eze Dope over regular, you can see the builds I did with Eze Dope.  There is a steep learning curve with Eze Dope but it works great once you figure it out.  I have some fragile frames covered with Esaki without pre shrinking and still have no warps.  The only reason I still use regular dope...……..nostalgia but if I use regular dope I mainly cover with Domestic tissue to prevent warping.  Dumas puts out a nice video on covering with tissue and I will link you to a builder on youtube that will help with covering.
https://www.youtube.com/playlist?list=PL5eGa5ollj8MO1J03Nl2FmfV_VQ1RzmCK
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vtdiy
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« Reply #8 on: December 19, 2018, 10:11:51 AM »

Thanks Scigs! That will definitely help

I saw your EZE dope posts a long time ago with Peter Rake on RCG, and I bought a bottle. I was planning to use that. I don't have Esaki yet, though I sent for some recently. But originally I was planning to use domestic tissue. I might still.

I loved the look of the Super Cub you did in that Peter Rake thread -- red and yellow. Wish J3's weren't always yellow.
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vtdiy
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« Reply #9 on: January 10, 2019, 10:47:46 AM »

I needed some more balsa strips, as I've mostly used up the 1/16" square ones I had bought. Also I need 1/8" x 1/16" for the wing, so I tried using a paper cutter that I had bought at WalMart some time ago for cutting tiled plans, as a balsa stripper. A friend had mentioned this could be done. I put some masking tape on the ends, and marked it with 1/16" and 1/8" marks. With some adjustment and practice, I ended up with some bundles of stripped stock, and am ready to build the wing.
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vtdiy
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« Reply #10 on: January 10, 2019, 03:40:45 PM »

I cut out, sanded and notched all of the ribs from 1/32" stock:
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vtdiy
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« Reply #11 on: January 11, 2019, 01:30:26 PM »

I'm trying to figure out how the wing tip bow connects/fairs into the leading edge. The bow is 1/16" square section, and the LE is 1/8"x1/16" vertical. On the plans they are just shown as butting together and the tip rib is there, too. But that would make a step for the tissue, and wouldn't be very strong.
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Yak 52
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« Reply #12 on: January 11, 2019, 01:37:16 PM »

I think I extended the LE and scarphed the laminated tip to it.

http://www.hippocketaeronautics.com/hpa_forum/index.php?action=dlattach;topic=10532.0;attach=67198;image

http://www.hippocketaeronautics.com/hpa_forum/index.php?action=dlattach;topic=10532.0;attach=67192;image
Piper Cub "1983" Build
Piper Cub "1983" Build
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LASTWOODSMAN
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« Reply #13 on: January 11, 2019, 01:39:41 PM »

Hi vt.  Maybe add some tiny gussets for strength?  It does look pretty flimsy ...    Lips sealed

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vtdiy
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« Reply #14 on: January 11, 2019, 02:50:55 PM »

Thanks Yak52! Did your Leading edge go over the tip bow with a notch?

Also it looks like you added a triangular sheet former going from the end of the 1/16" spar to the bow -- or is that just a 1/16" strip?

Thanks Richard! I was thinking that's what I would do because I had already cut the LE to exact length and pinned in the ribs. But, duh, I forgot I hadn't glued anything yet, and I could just discard the LE strips and make new longer ones.
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vtdiy
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« Reply #15 on: January 11, 2019, 03:08:58 PM »

Hmm,  just checking Scigs original build thread photos, it looks like the tip bow on that one is raised up, not running flat on the bottom of the wing. Just the 1/16th spar to the tip.

Looks like yours, Yak 52, was flat to the table..which is why the former is there. Hmmm.....what to do.....

I think your way might be stronger for me at my own build ability, and might be easier for me to cover without warping or breaking it.
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Yak 52
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« Reply #16 on: January 11, 2019, 04:19:41 PM »

Just dug the model out for a look...

Thanks Yak52! Did your Leading edge go over the tip bow with a notch?

I can't remember to be honest and it's hard to tell from the model.


Also it looks like you added a triangular sheet former going from the end of the 1/16" spar to the bow -- or is that just a 1/16" strip?

Yes, I did them flat and added a sheet former or gusset there as you say. I had issues with the bow warping upwards as you can see - perhaps Scigs method would pull more equally. Really my problem was not pre-shrinking the tissue as it's quite a light structure.

I added a gusset at the TE and you can also see through to where I've made repairs and added bits to attempt to control the warp.

Jon
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vtdiy
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« Reply #17 on: January 14, 2019, 10:21:26 AM »

Thanks kindly, Jon!

I really spent a long time debating what to do over this. I've never done a tip bow lifted before, and wasn't sure how to set it, or how it connected. The way you handled your wing tips, with a horizontal bow seemed straight forward, and what I really wanted to do.

But I just started fiddling around with raising them using a balsa spacer under, and I could see how the bows could feed into the LE and TE at an angle. I had already replaced the pre-cut TE stock with longer pieces so they overlapped the tip bows, instead of butting.

I finally just made a decision to try to go with the way it was probably intended, and decided to raise them half the height of the full depth of the tip rib. That put them about 0.175" above the table. And that's what I did. My hope is that raising them will equalize the strain on the shrunk tissue to help avoid warping the bow. I don't really know, of course. But your suggestion about this, Jon, just seemed to make sense. Thank you again for your help!

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vtdiy
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« Reply #18 on: January 15, 2019, 05:36:45 PM »

Where I am at present...the main components are mostly complete.
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Yak 52
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« Reply #19 on: January 15, 2019, 05:39:19 PM »

Looking great  Smiley
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vtdiy
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« Reply #20 on: January 15, 2019, 05:57:44 PM »

Thanks Jon!

Question....did you have to cut the tailpost where the slot is?

I can't see any other way to get the horizontal stabilizer in after it gets covered.

If you did cut it, did you glue a little piece back in after the stabilizer was finally mounted on the plane?

Thanks!
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