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Old Mar 15, 2013, 03:02 PM
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United States, MN, St Paul
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How do you align a tapered ribs on a Polyhedral wing?

Total noob builder here so please forgive any stupid questions.

I've started building a P2V-7 Neptune C/L model and started to realized how little I actually knew about model airplane building

I've cut my spars and ribs and started gluing the outside ribs 1st. Making sure that they were square to the spars and completely vertical. I didn't, however make sure that they were pitched at the same angle. As a result at least one is quite out of line with the others. Just glad I stopped after the 4th rib.

So... Anyone have pointers on how to remove a CA glued balsa joint and / or how to align tapered ribs on a polyhedral wing, the right way? Or any other suggestions on how to get this build back on track.

Thanks for any help.
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Old Mar 15, 2013, 08:10 PM
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winston mo
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acetone is a great debonder. Does your plans have instrutions
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Old Mar 15, 2013, 10:24 PM
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Thanks for the response kerwin50.

Does acetone have any detrimental effects on the balsa? I saw that it could be used but with what I've read on the effects of glow fuel I was hoping to avoid putting any chemicals on the wood for fear that it might damage / weaken it.


The plans I'm working with were originally published in the April 1961 issue of Aeromodeller. The build article says "Cement wing ribs W1 to W5 on the spar (over the plan) and then the 1/16in. sheet trailing edge and 1/2 in. by 5/8 in. leading edge (cut down from 3/4 in. by 3/4 in.) and then shape to section." That's it as far as instructions go.

I guess I don't even know if the ribs on the end of the spar should be vertical when the spar's root is horizontal or vertical when the spar's outer end is horizontal or some thing else.

Help please
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Old Mar 15, 2013, 10:47 PM
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United States, WA, Port Angeles
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generally you use an 1/8 sq. or so depending on the size of the model!

placed under the ribs behind the spar, to keep the ribs level, imagine a centerline going through the middle of the rib horizontally and place a temporary stringer under ribs to keep the rib level!

if the planes I have built, didn't have tabs, then there was a brace under the ribs ta keep them level!

this method does not take into account any was-out
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Old Mar 16, 2013, 03:04 AM
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Thanks Wiskykid for the help.

Just to make sure I understand correctly, I dry fit the rib using an imaginary line half way up the thickest part of the rib and make that line level, then shim the rib and glue?

What about the ends of the wings that are angled up?

According to the article / plans the model's stats are
AUW - 24 oz
Engine - 2x 1cc M.E. Hurons (I'm using 2x .074 ok cubs)
Wing span - 38'
Link to plans - http://www.outerzone.co.uk/download_...an.asp?ID=1553

Thanks again I appreciate the help!!!
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Old Mar 16, 2013, 12:04 PM
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ok I got your plans ta download, and this is what I would do, take and copy the angle of the outer wing spar, (a lil over sized ) s o you can adjust it side to side! you could probably use some card bard or say like some scrap balsa sheet! and put that under the trailing edge of the outer wing panels, after you level out the center ribs, then slide the temp angle brace you made to align the ribs up!

hope I didn't confuse you too much!
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