Any tips for straightening a glider body?

[Charles_McG]

So, I’m working on a 228% Tercel upscale. The body of the glider is box construction - a foamcore / basswood laminate with a balsa cap. Most of the balsa cap is not installed.

While test fitting the tail pieces, I noticed that the body has a 3mm bow.



I’m looking for suggestions on how to straighten it. One thought is that I might be able to do it when I glue the rest of the cap on.

 

[Crawf56]

Let me start by giving the disclaimer: I have not ever tried this modification to a glider like this. Your mileage may vary.

I also build radio control airplane models. One way to modify balsa wood is to wet the wood with water, then stress the wood in the shape you want. Once the balsa wood dries (overnight), it retains some portion of the modified shape.

For example, if I want to get 1/8" balsa to conform better to a curved surface. So, I use a brush to apply water to the inner and outer surface of the balsa. I then use masking tape to force the balsa to adhear to a curved surface, like a 4" diameter tube. After the balsa dries, it has a curved shape, to better fit something like an aircraft curved fuselage.

But this is basswood & foam. Not sure how this technique would work.

 

[Crawf56]

For your case, I would suggest:

1) Appling water to the fuselage.
2) Place the fuselage on a flat surface.
3) Immediately place weights on the fuselage, so that it conforms to the flat surface.
4) Let dry for 24 hours.

NOTE: You might use something like wax paper to protect your flat surface and weights [books?] from the wet fuselage. Do not wrap the fuselage with wax paper, because you want it to dry out.

And I do not know if this solution will work for this case.

 

[Crawf56]

Another thought: What if you did the flat surface & wax paper (or saran wrap) & weights, but left one edge of the basswood/foam fuselage exposed? You could then apply THIN FOAM SAFE CA to the fuselage, and this might hold the fuselage relatively flat.

Don't know if this would work or not.

Would like to hear opinions on these suggestions.

 

[Charles_McG]

I’ve had other suggestions with combinations of heat and moisture. I’m working on the wing sections, so I’m not in a rush.

I think that when the time comes, I’ll moisten/heat and then clamp it like I did originally- but with a little shim to reverse the curve.



And I’ve shaped balsa with ammonia and wrapping. Even on this project.

 

[Charles_McG]

Wetting with ammonia water and reclamping with a spacer at the nose end to create a counter warp seems to have worked.

 

[Crawf56]

Very good.