G-spotter Posted August 24, 2006 Share Posted August 24, 2006 No, cause FF is calculated based on length of unstretched rope. Quote Link to comment Share on other sites More sharing options...
bstach Posted August 26, 2006 Share Posted August 26, 2006 Actually, Robmcdan is correct. The formula holds for both static and dynamic ropes. Which makes sense considering FF is not a measure of the force on the rope, but a *relative* indication of the force of falls of different lengths given the same rope and climber. In deriving the formula for the maximum force in a fall, the factors containing the rope stretch cancel out. Then you are left with factors containing a bunch of constant stuff -weight of the climber, properties of the rope - and the fall factor. The terms of the fall factor are the only things the leader has control of (by when/where he places gear) - all the other things are constant - which is why the FF is a useful measure. Â Also, it has been stated several times in this thread that reeling increases the fall factor. This is not exactly correct. In fact, for fall factors < 1, reeling will decrease the FF. For fall factors = 0, reeling has no effect on the fall factor. For fall factors > 1, reeling will increase the fall factor (so Dru's post is correct, just incomplete). Go ahead, do the math. Â : mathdance : Â Also, note there is a difference between 'reeling' and back-pedaling (running downhill) wrt calculating FF. If you back-pedal, you are not shortening the total amount of rope absorbing the fall - to do this you actually need to pull rope through the ATC (as in 'reeling'). Of course, you still increase the force on the rope when you run, as you now have two masses falling downhill that the rope must bring to a stop. Â Quote Link to comment Share on other sites More sharing options...
archenemy Posted August 28, 2006 Share Posted August 28, 2006 Is anyone else getting mildly aroused by all this math talk? Quote Link to comment Share on other sites More sharing options...
catbirdseat Posted August 28, 2006 Author Share Posted August 28, 2006 Also, note there is a difference between 'reeling' and back-pedaling (running downhill) wrt calculating FF. If you back-pedal, you are not shortening the total amount of rope absorbing the fall - to do this you actually need to pull rope through the ATC (as in 'reeling'). Of course, you still increase the force on the rope when you run, as you now have two masses falling downhill that the rope must bring to a stop. Â By back pedalling, I am assuming you refer to the belayer. Sure it increases forces, but the idea is to prevent the leader from getting shredded on a slab fall. The forces aren't that great to begin with. Quote Link to comment Share on other sites More sharing options...
bstach Posted August 28, 2006 Share Posted August 28, 2006 Is anyone else getting mildly aroused by all this math talk? Â Thanks Archenemy, I was worried I might be the only one. Quote Link to comment Share on other sites More sharing options...
archenemy Posted August 30, 2006 Share Posted August 30, 2006 peas in a pod, I tell you, peas in a pod. Â Â Â Â I have a little question too. I've had a belayer tighten the rope up after I tell him I am in a sketchy spot (on TR of course). Anyone else admit to doing that? It is kind of like "pre-reeling" a falling loser, but it makes me feel better. Am I the only one on this? Â (please show work in math proofs to get full credit for your answer) Quote Link to comment Share on other sites More sharing options...
archenemy Posted August 30, 2006 Share Posted August 30, 2006 Post deleted by archenemy Quote Link to comment Share on other sites More sharing options...
G-spotter Posted August 30, 2006 Share Posted August 30, 2006 "falling loser" Quote Link to comment Share on other sites More sharing options...
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