Boomilever B/C

[Faustina]

How have you guys been connecting your tension and compression members?
If possible, draw a diagram (for my sake)

Have you read this (http://scioly.org/wiki/Aia%27s_Boomilev ... Distal_End) yet? That's pretty much what I did on a practice boom and it worked great.

[Aia]

I'm glad to hear it worked Faustina!

For reference, here's a link to my boomilever guide so people can read it from the top:
http://scioly.org/wiki/index.php/Aia%27 ... ever_Guide

[iwonder]

Have these 'radical' designs been tested yet? If so, how well have they held up?

The 'radical' part has been tested(i.e I've checked the compression member and the distal end to make sure they can hold up) this weekend the plan is too finally build 2 full booms and see if it works in reality.

[retired1]

If you post the weight held and the boomilever weight, we will all have a target to shoot for.
Sounds like a competition before the regionals.
Let's have fun with this and learn or be challenged.

[fanjiatian]

How have you guys been connecting your tension and compression members?
If possible, draw a diagram (for my sake)

Have you read this (http://scioly.org/wiki/Aia%27s_Boomilev ... Distal_End) yet? That's pretty much what I did on a practice boom and it worked great.

Yup! I was wondering if anyone thought of other ways to do so.

[iwonder]

Throwing this one together :/ (to much glue, no jig, struggling to keep it square and not taking weights...). One question... How do people know what forces are on certain members(basically how do they know when to pretension components or not)

[retired1]

I have a computer program that I bought a long time ago that not only gives that, but shows where it failed and at what weight.
There is a free one that I have seen on the internet, but may only be 2D rather than 3D. I think that there are links somewhere at soinc or sciology
If I see it again, I will post it.
I have not been there in a while, but check out the West Point bridge competition site also for links.

[iwonder]

Well I didn't bother to pretension anything this time anyways, but I'm just going to assume that the bracing for compression members should be pretensioned just like towers...

Finished, weighed all the pieces, the compression member is 9g(nothing fancy, the tube I had got ruined by the recent humidity changes), a .5(edit: I sanded .15g off)g base, and 1.64g in the tension members... if it all holds I think I'll be off to a good start... sadly, with my luck, it probably won't hold much :/

The completed boom is 11.41g(I used aia's distal end connection), after looking at it I'm not entirly convinced that the compression member will hold up vertically, but that remains to be seen after testing.

[thsom]

.35 g base?! 1.64g tension members?! those are outrageous stats

[iwonder]

No, No, No... .5g base, don't worry. I put .65g originally and then sanded .15g off to end up at .5g. However, yes, I do have 1.64g in the tension members, I'm not to sure they'll hold up however. Tomorrow I plan to gorilla glue in the tension members to the base, and then I should be able to test once the glue sets. I will update the total mass to account for the gorilla glue that I forgot about(shouldn't be too much).

Note: A quick check reveals that a pair of tension members known to handle the load weigh about 3g, but I believe from research over the summer that they are slightly(if not a little more than that) overkill, so mine may very well fail before the compression member, but I always build too light and work my way up throughout the season anyways.

Oh, and the base will be heavier, but since we don't have the rules, I have the luxury of deciding not to use a washer(which I don't have, also) and thus am able to make the base insanely small.