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What Happens in a Fall?

What Happens in a Fall?. Falling climber builds up momentum (force x time) When climber is ‘stopped’ (either by rope/anchor system or by hard deck) the resulting forces needs to be absorbed

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What Happens in a Fall?

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  1. What Happens in a Fall? • Falling climber builds up momentum (force x time) • When climber is ‘stopped’ (either by rope/anchor system or by hard deck) the resulting forces needs to be absorbed • Climbing rope (dynamic) acts like a SPRING and ideally absorbs most of this force (the maximum amount NOT absorbed by the rope is the rope’sIMPACT FORCE rating) • “Fall-factor” (larger numbers are worse) indicates SEVERITY of fall and is related to the ability of the rope to act as a good spring and absorb fall force (less rope equals less good spring) • The remaining force (impact force) is absorbed by the ANCHOR and THE CLIMBER • Actually, the anchor needs absorbs 1.7x to 2x of the impact force WITHOUT BREAKING (extra .7x to 1x due to the belayer force counter balancing the climber and stopping the fall)

  2. KEY: Climber Anchor Rope Fall Factor FALL FACTOR = Height of fall Total Length of rope out(ie. amount rope acting spring) 80’ 5 Fall Factor = = 0.0625 80 80’ 80’ 5’ Fall Slack in System 80’ Rope

  3. factor 2 factor 1 factor 0.5 factor 0.0625 fall: fall: fall: fall: rope out: 5’ 20’ 20’ 20’ 20’ rope out: 80’ rope out: rope out: 10’ 40’ approx force on anchor: 8-10KN approx force on anchor: 3-4KN approx force on anchor: 16-20KN approx force on anchor: 12-15KN KEY: Climber Anchor Rope Pro Fall Factor: Examples SLINGSHOT TOP ROPE FALLS LEAD FALLS

  4. Force on anchor is SUM of both Force from climber KEY: Climber Force from belayer Anchor Rope Anchor Forces • Anchor (naturals, gear, runners, webbing, ‘biners etc… ) needs to absorb 1.7x to 2x of the impact force • Ideally, anchor should be built to withstand 30KN of force (approx 1.5x worst case lead fall) Zero Motion (stopped): Belayer force EQUALS Climber force Anchor subjected to BOTH forces

  5. Anchor Forces: Details • Doubling fall factor results in approximately 1.4x increase in impact force • Ropes are rated for impact force from a 80kG climber and factor-of-1.77 fall • Runners and anchor need to absorb 1.7x-2x impact force of fall • Lead falls generate significantly more impact force than slingshot top rope falls More info: www.climbtennessee.com/train/fall.html www.bealropes.com/english.dir/forces.html

  6. Forces (approx) • 1KN = 220lb (ie. 1 person static) approx 1G • 10KN = 2200lbs (max from rope) approx 10G’s • 12KN = 2640lbs (ie. Injury/Death) approx 12G’s • 15KN = 3300lbs • 25KN = 5500lbs

  7. Speeds from falls (approx) • 1m = 3 feet = 4m/s = 10mph • 3m = 10 feet = 8m/s = 17mph • 6m = 20 feet = 11m/s = 24mph • 10m = 33 feet = 14m/s = 31mph • 20m = 66 feet = 20m/s = 44mph

  8. Energy from falls (approx)mgh & ½ mv2 • 1m = 980J = 4m/s = 10mph • 3m = 2940J = 8m/s = 17mph • 6m = 5880J = 11m/s = 24mph • 10m = 9800J = 14m/s = 31mph • 20m = 19600J = 20m/s = 44mph

  9. Strength of Webbing Gear Strength Cost • 2” Webbing 30kN ($0.55/ft) • 1” Webbing 18kN ($0.30/ft) • 9/16” Webbing 7-11kN ($0.22/ft) • 5mm Spectra 20kN ($1.05/ft) • 4mm cord 3kN ($0.20/ft) • 5mm cord 5kN ($0.25/ft) • 6mm cord 8kN ($0.35/ft) • 7mm cord 11kN ($0.40/ft) • 8mm cord 11kN ($0.50/ft) • Nylon runner 22kN ($2.0/ft – 0.75’, 2’, 4’ ) • Spectra runner 27kN ($3.5/ft – 0.5’, 2’, 3’, 4’ ) • Dynamic Rope (impact force) 7kN-10kN ($0.60/ft (approx): 165’, 200’, 230’)

  10. Strength of Gear Gear Useful Dimensions Strength • ‘biner 18-25kN / 6-9kN (gate open) • #1 Nut 4.3/ 9.1mm 2kN • #5 Nut 8.4/13.5mm 6kN • #6 Nut 10.2/15.5mm 10kN • #1 Hex 10.7/15.5mm 6kN • #3 Hex 13.9/20.1mm 10kN • 0.5 Tricam 16/28mm 10kN • 2 Tricam 28.5/41mm 15kN • 2.5 Tricam 32/47.5mm 18kN • 0.1 BD Cam 9.9-17mm 7kN • 0.2 BD Cam 10.2-16.2mm 8kN • 0.3 BD Cam 12.5-21.5mm 10kN • 0.75 BD Cam 24-39.5mm 16kN

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