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by pjspol
March 13th, 2018, 10:48 am
Forum: Towers B/C
Topic: Cost
Replies: 6
Views: 992

Re: Cost

The cost depends on what kind of jig you make and what specifications you order for wood. 36" x 1/16" x 1/32" sticks specified to a given amount of pounds per cubic foot cost about $8.25 each from Specialized Balsa, but if you cut your own, the 36" x 4" x 1/32 sheet also specified for density and wi...
by pjspol
January 29th, 2018, 6:46 pm
Forum: Towers B/C
Topic: Towers B/C
Replies: 524
Views: 69921

Re: Towers B/C

I am not sure if this has been discussed at length this year, but I was wondering about the benefits / downfalls of utilizing a rectangular, bridge-like base rather than the typically square base. This seems especially pertinent because of the wide angle on bonus towers. I have seen some high level ...
by pjspol
December 20th, 2017, 4:12 pm
Forum: Towers B/C
Topic: Wood
Replies: 40
Views: 4634

Re: Wood

For estimating the modulus of elasticity, I used an extrapolation equation that I got from an MIT study on balsa properties.
by pjspol
December 19th, 2017, 9:43 am
Forum: Towers B/C
Topic: Wood
Replies: 40
Views: 4634

Re: Wood

Regarding the 0.55 multiplier for towers braced with only X's, I ran into a bit of an issue. One of the towers (Division C) that I built last season used 3/32 inch square main compression members with a mass of 1.6 g per 36" stick. The tower held full 15 kg for about 10 seconds and then shattered. A...
by pjspol
November 24th, 2017, 8:46 pm
Forum: Towers B/C
Topic: Wood
Replies: 40
Views: 4634

Re: Wood

Balsa Man, When you say "The effective length factor for all Xs is significantly less; about 0.55.", are you referring to the K value in Euler's Buckling theorem explicitly or to some derivation? If explicitly, then X braces should be much better than X s and ladders because the value is squared in ...

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