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Arecibo

Discussion in 'Fred's House of Pancakes' started by tochatihu, Nov 9, 2020.

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  1. tochatihu

    tochatihu Senior Member

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    Planned salvage was to helicopter out the 900 ton suspended platform (??). I really don't know that lift capacity exists. But it would have involved people cutting cables that then would zing! Did not understand it at all.

    Heavy ground cranes exist, but road access is an issue.

    A clear description of how the towers and platform were installed might illuminate the situation. However, it did not happen, and eventual cleanup will be much less kinetic.
     
    #61 tochatihu, Dec 6, 2020
  2. Rmay635703

    Rmay635703 Senior Member

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    100 ton is the most that can be finagled into a cooperative chopper lift, so yeah 900 ton couldn’t even happen with many copters
     
    #62 Rmay635703, Dec 6, 2020
    fuzzy1 and tochatihu like this.
  3. tochatihu

    tochatihu Senior Member

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    The engineering plans may be public but I have not read them. Frankly and with not much basis, my impression is that after the second cable snap, they were just standing clear and waiting for gravity.

    ==
    At eastern edge of island is Luquillo forest. Back in the day, a hurricane simulation experiment was considered to be done with helicopter downdraft blowing branches off trees. It would have been really messy, but fun to watch :) It was eventually done in conventional ways; tree climbing and pruning. So everything could be weighed and transferred to +input plots.
     
    #63 tochatihu, Dec 6, 2020
  4. fuzzy1

    fuzzy1 Senior Member

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    900 tons almost 500 feet up. That seems like an extremely heavy lift a long way up, even if they removed or scrapped a bunch of reflectors panels in the center to drive the cranes almost directly underneath. If trying to reach over from just outside the dish ... :eek::eek::eek:
     
    #64 fuzzy1, Dec 6, 2020
  5. Rmay635703

    Rmay635703 Senior Member

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    gotta wonder how it was done originally, 900t weight is nothing with proper machinery
    Wind Industry | Digging & Rigging, Inc.

    gotta wonder what was used and where it went?

    maybe piecemeal assembly after the cable was run?
     
    #65 Rmay635703, Dec 6, 2020
    Last edited: Dec 6, 2020
  6. fuzzy1

    fuzzy1 Senior Member

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    https://www.liebherr.com/en/usa/products/mobile-and-crawler-cranes/mobile-cranes/liebherr-mobile-cranes/ltm-1750-9.1.html

    https://cranenetwork.com/uploads/specs/765dcf7444b382d8a45cdd63d.pdf

    Sorry, but if I'm reading spec sheets properly, that crane isn't even close. You can't have max weight and max lift height at the same time. Its maximum rated lift capacity is only for its shortest possible configuration, 16.3 meters, and for central axis offset of only 3.0 meters, and no swivel. See pages 8 and 16.

    For a 150 meter hook height, it needs to be configured by the last illustration on page 10, more detail illustrated on page 88. Page 87 gives the max load for that configuration at various overhangs- 13.3 tons at 48 m overhang (150 m high). It can reach even higher to 154 m at that config's minimum overhang of 38 m, but load decreases to 7.8 tons. (Page 86 shows a slightly shorter config that just reaches 150 m, but with lower load capacity at that position.)

    But at least those ratings are metric tons, not English tons, so increase by 10% for the later. ;)

    upload_2020-12-6_20-45-29.png

    upload_2020-12-6_20-50-32.png

    upload_2020-12-6_20-48-31.png
     
    #66 fuzzy1, Dec 7, 2020
    Last edited: Dec 7, 2020
  7. fuzzy1

    fuzzy1 Senior Member

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    It was originally done with much less equipment on the platform, so probably considerably lighter. And also without that very nice reflector dish of aluminum panels below, just a steel wire mesh as a "mirror". I'm guessing that the original platform was assembled on the ground, then hoisted up by the support cables, possibly before the original mesh was even installed, at least at the center.

    The upgrade to the nicer reflector panels happened a decade later.
     
    #67 fuzzy1, Dec 7, 2020
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