Boomilever B/C

[tsingh]

I noticed that everyone was making a huge deal about rule 5a.v (the contact width lines). However while designing by boomi for this year I found that the angle that the diagonal compression members made with the perpendicular line from the testing apparatus is only about 2.12 degrees which increases the load on the compression members from 43.29 kg (boomi constructed according to last year's rules) to 43.32 kg, if carrying max weight. (This is all for a basic tension boomilever).
This is why I don't really see this rule change as that significant to the event, besides of course the fact the it will be a little more difficult to build. Am I missing something here?

[Unome]

I noticed that everyone was making a huge deal about rule 5a.v (the contact width lines). However while designing by boomi for this year I found that the angle that the diagonal compression members made with the perpendicular line from the testing apparatus is only about 2.12 degrees which increases the load on the compression members from 43.29 kg (boomi constructed according to last year's rules) to 43.32 kg, if carrying max weight. (This is all for a basic tension boomilever).
This is why I don't really see this rule change as that significant to the event, besides of course the fact the it will be a little more difficult to build. Am I missing something here?

The increased difficulty of building is probably the biggest challenge imo.

[123445]

What are some good vertical members I should try. Right now I'm use 1/16x1/16 balsa, and my vertical members are bending/breaking at ~7-8kg.

[MadCow2357]

What are some good vertical members I should try. Right now I'm use 1/16x1/16 balsa, and my vertical members are bending/breaking at ~7-8kg.

1/16" square for main compression beams? That's kinda thin. I'd use at least 1/8" square for a modified tower chimney design, or 1/2" by 1/8" for a regular one.

[123445]

What are some good vertical members I should try. Right now I'm use 1/16x1/16 balsa, and my vertical members are bending/breaking at ~7-8kg.

1/16" square for main compression beams? That's kinda thin. I'd use at least 1/8" square for a modified tower chimney design, or 1/2" by 1/8" for a regular one.

I meant I was using 1/16 square for the vertical members not the compression.

[stevepilot]

Does anyone know if it would be beneficial to brace both the top and bottom sides of the compression beam? Currently we only brace the top, however it is clear from testing that this results in a twisting motion between the two compression beams. Would bracing both sides be worth the extra weight, and is anyone doing so right now? Or does anyone have any experience with bracing only the bottoms?

[MadCow2357]

Does anyone know if it would be beneficial to brace both the top and bottom sides of the compression beam? Currently we only brace the top, however it is clear from testing that this results in a twisting motion between the two compression beams. Would bracing both sides be worth the extra weight, and is anyone doing so right now? Or does anyone have any experience with bracing only the bottoms?

I brace both top and bottom, works for me.

What are some good vertical members I should try. Right now I'm use 1/16x1/16 balsa, and my vertical members are bending/breaking at ~7-8kg.

1/16" square for main compression beams? That's kinda thin. I'd use at least 1/8" square for a modified tower chimney design, or 1/2" by 1/8" for a regular one.

I meant I was using 1/16 square for the vertical members not the compression.

I assumed you meant "main compression beams" when you said "vertical members". If you mean bracing, I've been getting by with 1/16" by 1/32" strips.

[sciolyperson1]

By vertical bracing, I assume they mean bracings that connect the main tensions and main compressions; try going for 1/8 x 1/16 or 1/8 x 3/32 instead of 1/16 x 1/16.

[Lorant]

By vertical bracing, I assume they mean bracings that connect the main tensions and main compressions; try going for 1/8 x 1/16 or 1/8 x 3/32 instead of 1/16 x 1/16.

Effective arrangement of 1/16 x 1/16 will cut weight and should yield equal if not better results, it really all depends on the arrangement of the vertical bracings.

[sciolyperson1]

By vertical bracing, I assume they mean bracings that connect the main tensions and main compressions; try going for 1/8 x 1/16 or 1/8 x 3/32 instead of 1/16 x 1/16.

Effective arrangement of 1/16 x 1/16 will cut weight and should yield equal if not better results, it really all depends on the arrangement of the vertical bracings.

1/16 x 1/16, under both tension and compression, can support minimal weight. 1/8 x 1/16 or even 1/4 x 1/16 balsa under tension would be far more optimal.