Gluing Balsa wings together

[John_lennon]

I've come across threads, posts, and build videos where I've seen people gluing together 2-3 different pieces of balsa to make 1 wing. How do they hold up it seems they'd break apart fairly easy. Why not use larger balsa stock to cut out the full wing even if a couple sheets are required. I'm sure it's a cost thing but to a large company like them I can't imagine it'd cost that much more overall. Are a lot of kits like this from other manufacturer's? I'd love to get a kit with real wood wings they seem like they'd be the most sturdy out of all the options.

 

[neil_w]

Goal is to keep the wood grain parallel (or as close as possible) to the leading edge, for strength. At the same time, the grain will almost always end at the body tube, so the balsa-balsa glue joints are not really the key to the strength.

Complex fin shapes are therefore often built as multi-piece, to keep each segment of the fin strong. Here's a simple example:
https://www.rocketryforum.com/threads/diamond-cutter-build-thread.129671/post-1520570A more complex example: https://www.rocketryforum.com/threads/starship-avalon-build-thread.136389/post-1662003
A very complex example: https://www.rocketryforum.com/threads/alcubierre-build-thread.148195/post-1821755

Sometimes, keeping the grain direction correct makes it impossible to fit even a fairly simple fin on a 3" or 4" balsa sheet, so once again multi-piece arrangements are used.

When building with plywood or fiberglass, there is no concern over woodgrain direction, so the fins would more typically be one-piece (although large wings on large rockets could become impractical at some point).

 

[Spitfire222]

I can't imagine it'd cost that much more overall.

You'd be surprised....

But as Neil mentioned, grain direction is another important factor. Larger kits will trend towards plywood fins, but on the smaller ones, lightness is key so we stick with balsa, even if tends to crack/break on rougher landings.

(PS: Balsa is definitely a "real" wood. Ironically, it's classified as a hardwood, if I'm not mistaken!)