nigelswift
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Re: Do we need ropes?
Sep 17, 2003, 09:27
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As I understand it Gordon, the pole would work for a very shallow angled stone so only a small stone-tipping tower, if any, would be needed
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GordonP
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Re: Eh?
Sep 17, 2003, 09:28
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While you are doing all that we could have finished the job and gone for a pint
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nigelswift
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Re: Hole Profiles
Sep 17, 2003, 09:31
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Absolutely agreed. But there may not be a steep slope near the BBC stone (do you know?) and we can't find ourselves a 40 tonner at the bottom of the original hill.
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Steve Gray
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Re: Do we need ropes?
Sep 17, 2003, 09:39
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Almost. Though we are discussing this in several independent threads and I have already suggested that a 40 foot pole might suffice.
My problem with the tower is that it's an ideal structure for raising a stone vertically, but not for handling large side loads and it's very difficult to make it strong enough. If anything breaks under the strain, then 6 people could come crashing down from 24 feet. I don't think that any engineer could convince the Health and Safety Executive that it was not a risk.
During the levering-up of the stone people are on independent towers, some 20 feet away from the main tower. If this main tower is only 14 feet high and it falls over they are far enough away to be safe.
Similarly, people working a rope-based system are on the ground. If the rope breaks and the stone falls there is nobody in its path. The only risk is whiplash from the rope.
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Steve Gray
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Re: Neolithic Rope!
Sep 17, 2003, 09:46
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From a H&S viewpoint we would probably have to exceed the estimated breaking strain by a considerable margin.
If, for example, it was thought that a 2" neolithic rope would have been up to the job, then we should use a 2" modern rope whose breaking strain will be considerably more, thus satisfying H&S, but its handling characteristics should be somewhat similar. I think this would be better than using a 1" rope with a similar breaking strain.
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GordonP
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Re: Do we need ropes?
Sep 17, 2003, 09:48
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As I see it levering at 90 degrees against a diagonal strutt places no side load on the tower at all.
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nigelswift
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Re: Neolithic Rope!
Sep 17, 2003, 09:49
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It IS very expensive, maybe £100+ per metre for the thickest (unless they decided to do it for the prestige), and you're right, the point may not be worth proving at that price, but I don't think we should lose sight of the fact that we may have a very sexy product here and be able to obtain some big sponsorship and grants. Once the website is up, and if we get it right, we can approach any number of potential sponsors with quite a degree of cred. I keep thinking of £100K lottery grant for the Millenium Bluestone project... we're going to do something much more spectacular, and so far we're only thinking of an expenditure amounting to a lorry load of timber. £3K to buy rope in exchange for a mention would be cheap publicity for a lot of firms.
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Wotan
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Re: Eh?
Sep 17, 2003, 10:07
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now youre talking!
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Steve Gray
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Re: Do we need ropes?
Sep 17, 2003, 10:13
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Yes, you are quite right, levering off a strut at 90 deg does not produce a side load and as you continue levering the angle will decrease so that a vertical load is produced, which the tower can absorbe quite happily. However, the struts would have to be quite long (40 feet?) for a 24 foot tower and would need to be moved and re-anchored between each levering operation because they must always act at the fulcrum point in order to achieve the 90 deg requirement.
As I said before, I'm not "against" or "for" any particular method. I think that ALL theories need to be considered and then we reject those which don't stand up to scrutiny. Those that remain are candidates for testing.
I have to go out now, so this will be my last post for a few hours. I'll catch up later.
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nigelswift
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Re: Eh?
Sep 17, 2003, 10:14
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Count me out...
http://www.pbm.com/pipermail/hist-brewing/2001/003074.html
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