Hi, Rick;
It is possible to generate 20 000 lbf into rigging. The piece being rigged does not need to be 20 000 lb itself. As the piece falls, it also accelerates and has velocity. While it is falling, it moves through a distance. At this point one uses the momentum equations to determine the actual momentum the piece has as it's falling. Once the piece starts to decelerate, which is a negative acceleration, then the force in the rope can be determined by how much the rope stretches to stop the deceleration of the falling piece. The less the rope stretches, the stronger the rope needs to be to decelerate the piece to 0 and more force is experienced by the rigging. Ideally, the rope stretching to stop the piece from decelerating generates the forces in the rigging system. The key to understanding these concepts are knowing velocity and distance-momentum-affect the system.
For a 20 000 lb trunk, the rigging can be set up in another tree in a gin pole type configeration. The rigging will most likely be attached at the top of the spar. First, all the trunks weight rests on it's stump. A notch can be cut and once the spar starts moving, it's weight is distributed between the rigging and the hinge. Depending on the angle the spar makes with horizontal and vertical lines will help determine how much force is generated to the rigging. One needs to do math and/or use empirical data from a device like a dynamometer to find when a 20 000 lb trunk will generate 20 000 lbf into rigging. Going back to rope characteristics, it will also depend on the work the rope does to find when 20 000 lb is reached.
Joe
It is possible to generate 20 000 lbf into rigging. The piece being rigged does not need to be 20 000 lb itself. As the piece falls, it also accelerates and has velocity. While it is falling, it moves through a distance. At this point one uses the momentum equations to determine the actual momentum the piece has as it's falling. Once the piece starts to decelerate, which is a negative acceleration, then the force in the rope can be determined by how much the rope stretches to stop the deceleration of the falling piece. The less the rope stretches, the stronger the rope needs to be to decelerate the piece to 0 and more force is experienced by the rigging. Ideally, the rope stretching to stop the piece from decelerating generates the forces in the rigging system. The key to understanding these concepts are knowing velocity and distance-momentum-affect the system.
For a 20 000 lb trunk, the rigging can be set up in another tree in a gin pole type configeration. The rigging will most likely be attached at the top of the spar. First, all the trunks weight rests on it's stump. A notch can be cut and once the spar starts moving, it's weight is distributed between the rigging and the hinge. Depending on the angle the spar makes with horizontal and vertical lines will help determine how much force is generated to the rigging. One needs to do math and/or use empirical data from a device like a dynamometer to find when a 20 000 lb trunk will generate 20 000 lbf into rigging. Going back to rope characteristics, it will also depend on the work the rope does to find when 20 000 lb is reached.
Joe
