Importance of span-wise stiffness

[David_Stack]

Good Morning All;

Started construction on a vintage North Coast Rocketry EZ Slider B boost glider (a George Gassaway design I believe).

The 1/8" balsa stock supplied for the wing is split along the grain. I cut a replacement from a sheet of 1/8" balsa that I had on hand. In working with the two I noted a discernable different in weight, so pulled out the gram scale. Kit supplied piece, 11.7 grams, the piece I cut from my stock 6.8 grams.

Normally I wouldn't hesitate to use the replacement, but just for fun I secured both to my benchtop and loaded them with weight. The wing supplied with the kit deflected half as much as the replacement.

How important is span-wise stiffness; should I use the wing supplied with the kit (I repaired with thin CA), or save myself several grams and build it out with the replacement stock?

As I am writing this I just realized that the construction of the model and the way the wing is affixed may allow it to be swapped out even after the model is finished. I need to go read through the instructions again, perhaps I build both wings and then I can do A-B comparisons after...

Thanks as ever

 

[TheAviator]

Good Morning All;

Started construction on a vintage North Coast Rocketry EZ Slider B boost glider (a George Gassaway design I believe).

The 1/8" balsa stock supplied for the wing is split along the grain. I cut a replacement from a sheet of 1/8" balsa that I had on hand. In working with the two I noted a discernable different in weight, so pulled out the gram scale. Kit supplied piece, 11.7 grams, the piece I cut from my stock 6.8 grams.

Normally I wouldn't hesitate to use the replacement, but just for fun I secured both to my benchtop and loaded them with weight. The wing supplied with the kit deflected half as much as the replacement.

How important is span-wise stiffness; should I use the wing supplied with the kit (I repaired with thin CA), or save myself several grams and build it out with the replacement stock?

As I am writing this I just realized that the construction of the model and the way the wing is affixed may allow it to be swapped out even after the model is finished. I need to go read through the instructions again, perhaps I build both wings and then I can do A-B comparisons after...

Thanks as ever

I've built a George Gassaway Stiletto B with very light wood, though I think I built it with 3/16" wood. With 1/8" thick, I'd be inclined to keep the heavier wood.

 

[Rktman]

Depends on your preference. If building for competition and performance, then by all means go with the lighter balsa.

I personally build for strength and longevity, so prefer using denser C-grain balsa.