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by rjm
January 10th, 2013, 6:07 pm
Forum: Boomilever B/C
Topic: what is meant by Clearance from Contact Depth Line
Replies: 6
Views: 3518

Re: what is meant by Clearance from Contact Depth Line

Len is correct, portions of the structure can be lower than the contact line for whichever division you are in. It just can't touch the wall lower. So, if you come up with geometry for your boom which extends out and down, that's okay. There is an ultimate limit, the loading block may not start out ...
by rjm
December 23rd, 2012, 11:55 am
Forum: Boomilever B/C
Topic: what is meant by Clearance from Contact Depth Line
Replies: 6
Views: 3518

Re: what is meant by Clearance from Contact Depth Line

Here's a comment about that "Contact Depth Line". The rules as adopted are virtually a repeat of the 2007/2008 rules. As the rules were being written last Spring, there was interest in developing additional challenge, and also in capturing an additional measurement to be used in tie-breaking. These ...
by rjm
September 23rd, 2012, 6:21 pm
Forum: Boomilever B/C
Topic: Boomilever B/C
Replies: 622
Views: 67100

Re: Boomilever B/C

Just a couple of quick comments on some of these posts: As always, these do not count as official clarifiactions. Slick/smooth surfaces are almost always more demanding of a structure, regardless whether it is a boom, bridge, or tower, than a coarse or tacky surface. For compression-style boomilever...
by rjm
May 21st, 2012, 8:46 pm
Forum: Towers B/C
Topic: General Discussion
Replies: 353
Views: 57483

Re: General Discussion

I was pretty disappointed to see a tie in medals placement as well. Lakeshore's tower mass was 7.75 g prior to submitting for competition (I'm their coach), and carried the entire 15 kg. No idea about Auburn's mass. I didn't see the detailed results this year. I have been assuming that the measured ...
by rjm
December 4th, 2011, 7:07 am
Forum: Towers B/C
Topic: General Discussion
Replies: 353
Views: 57483

Re: General Discussion

You are correct, we got through writing the draft rules, editing and discussing, and had the rules published before we realized we left out the height definition. The old rules didn't need a height definition. It was clearly the intent to measure to the point of support, but I think it's better to s...
by rjm
October 26th, 2011, 6:42 pm
Forum: Towers B/C
Topic: General Discussion
Replies: 353
Views: 57483

Re: General Discussion

I'm glad you're having success with your three-legged towers. It is a considerable challenge to build them competitively. It takes perseverance to do it well. The disadvantages of three legged towers go beyond the geometric imperfections discussed by SLM. BalsaMan mentioned the fundamental problem i...
by rjm
September 30th, 2011, 8:29 pm
Forum: Towers B/C
Topic: General Discussion
Replies: 353
Views: 57483

Re: General Discussion

So far as checking the level of the test base and shimming the tower or base, I can only offer my personal opinion. Nothing official here, that's for the clarification process. Rule 2.c says that the ES will provide all testing and assessment devices. Rule 3.g says that the tower is a single structu...
by rjm
September 29th, 2011, 9:11 pm
Forum: Towers B/C
Topic: General Discussion
Replies: 353
Views: 57483

Re: General Discussion

The height scoring is the only substantial change to the towers. You could enter last year's tower without modification, if you wish. Rules changes are typically incremental, changing one or two things so that teams can build on the previous year's experiences and still keep the event interesting. M...
by rjm
September 19th, 2011, 8:14 pm
Forum: Towers B/C
Topic: General Discussion
Replies: 353
Views: 57483

Re: General Discussion

Tipping of the bucket as the sand flows in, as it piles up unevenly in the bottom of the bucket, will be taken up in the movement between links of a chain. So, all those hinge points in the chain make it unnecessary to distribute the sand in the bucket or worry about pivoting of the bucket at its ha...
by rjm
September 17th, 2011, 7:58 pm
Forum: Towers B/C
Topic: General Discussion
Replies: 353
Views: 57483

Re: General Discussion

I made the comment about the swinging/rotating bucket. If the bucket is allowed to swing like a pendulum, then the lateral movement of the mass is resisted by the friction between the loading block and the tops of the tower legs, and those in turn are held from lateral movement by stresses distribut...

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