huangyhg

airlifted structures
i am working on a project in an environmentally sensitive area with very limited access for construction equipment. we are considering airlifting (via helicopter) pedestrian bridges into place. has anyone used airlifting on a project before? do you have any resources or references on the rigging, lifting capability, etc.? any recommendations or info would be much appreciated.

i have never done this, but have made serious investigation on two occasions. the firms that provide the airlift service prefer to handle the rigging and other details. suggest that you contact them early for their input.
we have used ericsson skycrane to build transmission towers and i believe the lift limit is about 20,000 pounds, but your capacity is determined by the drag of the shape lifted because of the rotor downwash drag on the shape. if you have any buildings near the site, you may have shingle roof damage due to the rotor wash which can get over 100mph. ericsson is located near seattle, i think. do a google search on skycrane.
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i have been called "a storehouse of worthless information" many times.
i checked into that a number of years back.
at that time, here in the dallas area, the largest helicopter stationed here was good for 2500 lbs or so. for anything bigger, they had to fly something in from kansas city at $25,000 or so.
they also can't just pick up a load and take it across town- basically can't lift over anyplace where people are. so it might save you setting up a large crane, but won't necessarily allow you to fabricate offsite.

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