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-   -   Looking for tips: unwarping a glider body (http://www.oldrocketforum.com/showthread.php?t=17638)

aeppel_cpm 12-18-2018 09:30 PM

Looking for tips: unwarping a glider body
 
Iím working on a 2.28x Tercel, and Iíve noticed the body has picked up a bend.



Itís a 3mm bend.

The construction is basswood over foamcore. Iím planning on capping the laminate with balsa. Iíve only done the nose so far.

Any suggestions for straightening this thing out?

Jerry Irvine 12-18-2018 11:06 PM

Moisture and a press/books. If it turns in flight that is a good thing and requires less wing clay.

Just Jerry

LeeR 12-18-2018 11:46 PM

Another option is a heat gun. It works well, with moisture, to get parts straight. If clamping is difficult, you may even be able to hold it for a few minutes in the correct position long enough for cooling to cause it to set in its new position.

If you donít have a heat gun, you can get them for as little as $10 at Harbor Freight, using a 20% off coupon.

Ez2cDave 12-19-2018 12:15 AM

Quote:
Originally Posted by Jerry Irvine
Moisture and a press/books. If it turns in flight that is a good thing and requires less wing clay.

Just Jerry



I'm concerned that it might "spiral" or "corkscrew", during boost.

Dave F.

astronwolf 12-19-2018 05:21 AM

Quote:
Originally Posted by Jerry Irvine
Moisture and a press/books. If it turns in flight that is a good thing and requires less wing clay.

This. I'll add patience to that.

Maybe if you used something to anchor the glider to your work table in the position shown in the photo, like a book or somekind of weight. Use a rubber band to deflect the boom aft of the wing's trailing edge so that it's straight. You'll have to rig something up to do this. Moisten the boom in the area just aft of the trailing edge of the wing. Don't get the wing wet. Allow to dry overnight, and check for straightness the next day. Repeat if necessary.

aeppel_cpm 12-19-2018 08:40 AM

Quote:
Originally Posted by Ez2cDave
I'm concerned that it might "spiral" or "corkscrew", during boost.

Dave F.


I'm also more concerned about boost than glide.

Thanks for the suggestions, gents. I'm hoping the capping - turning the laminate into a box - will help stabilize it - but I'd like to get it straight first. I'll try heat before moisture, as I suspect moisture got me into this pickle in the first place. Laminated with TBII.

How I did the body, clamped to a launch rail.


And the capping around the nose. 1/32Ē balsa, ammonia shaped.

ghrocketman 12-19-2018 10:02 AM

If you moisten wood with ammonia water (Ajax, BoPeep, etc) the wood flexes much easier than with plain water.

Ez2cDave 12-19-2018 09:37 PM

Quote:
Originally Posted by ghrocketman
If you moisten wood with ammonia water (Ajax, BoPeep, etc) the wood flexes much easier than with plain water.




The use of Ammonia & Water would work on an all wood fuselage, but he used a foam "core" for the fuselage, with Basswood sides bonded to the foam.

On an all-wood fuselage, Steam could also be used, but I am concerned about how the foam might react to the heat.

I'm wondering if the warping was either caused by a reaction between the foam and the adhesive used or if the fuselage was un-clamped too soon, before it had fully dried / cured .

Dave F.

ghrocketman 12-19-2018 10:23 PM

I don't think ammonia would attack any foam.

Ez2cDave 12-19-2018 11:43 PM

Quote:
Originally Posted by ghrocketman
I don't think ammonia would attack any foam.


I wasn't thinking about the Ammonia attacking the foam. I was thinking that since the wood was bonded to the foam, the Ammonia would only penetrate the wood and, as a result, not allow the wood to remain straightened if the foam is causing the warping.

Dave F.


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