Abseiling: Quiet men and what they have done without ever mentioning it.

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john_morris_uk

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I was chatting to someone I know fairly well. (We used to live next door to each other when I lived near Exmouth and completely by co-incidence we now are in the same unit and have offices a few doors from each other.) I noticed he has a miners lamp on his windowsill and as we have just been given an old miners lamp we chatted about it. His is brand neww and is on a plinth because he was part of the team that did this:

What is the record for abseilling.(rapelling.)
Longest abseil: Team of 4 Royal Marines set distance record 3627ft, by abseiling down Boulby Potash Mine, Cleveland to shaft bottom on 2/11/93.

Read more http://www.kgbanswers.co.uk/what-is-the-record-for-abseilling-rapelling/4903926#ixzz2VWYEDjSG
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He's never mentioned it but when I asked, it lead to some remarkable trivia coming out in the conversation.

First of all, where do you get 3,700 feet of continuous rope? The answer is that Marlow Braids made it for them. One drum made specially of continuous braid line. It weighed so much that you couldn't abseil using it if it hung straight down, so they held the weight of it on the roof of the lift in the shaft and had the lift descend just below the abseiler. The abseiling device was in danger of getting so hot that it would melt (400 degrees from memory?) If you stop, then the descender would melt through the rope so they had a garden sprayer cooling the descender. The lift could only go just slow enough to allow the abseiler to decend just quick enough for the line not to melt the descender. The descent took 40 minutes and CANNOT be broken on earth as there isn't another mine with a vertical shaft that's any deeper. (Actually there is one, and its owned by the same mining company and they have stopped using the bottom levels as they are too dangerous. Be warned if you are tempted; if they ever decide to open the bottom levels to break the record, then the Royal Marines have first pick...)

The only way to beat the record would be to descend from a balloon and for the reasons above, that presents some technical challenges from the weight of the rope and its not the same thing.

Interestingly there are several claims for world record abseils that come nowhere near the event I have partly described above.

Anyway, some interesting trivia that I hadn't thought about until I chatted to him and its slightly boaty because its about ropes. I'll put the post in the lounge if people complain that its in the wrong place.
 
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Interesting challenges that are not really evident when one thinks about at first. A bit like winching the Titanic to surface, the weight of the wire rope was physically impossible to support itself at the required length. However, I don't quite understand the lift/rope bit. What happened when they got to the bottom and all the rope was above them and they were still hanging from it? Was the lift not a safety feature?
 
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Impressive indeed - but mostly you've tickled my problem-solving faculties :)

If I was tasked with beating this record, I'd go with the balloon approach. The problems with the weight of the rope and the heat only arise from using a conventional (fig-8?) descender, so the key to it is to design a braking device that works on a taut rope and doesn't heat up the rope-bearing surfaces.

First thing that occurs to me is that the rope should run round a rotating wheel, not a static piece of metal. The tension in the rope can pull it as tightly as you like onto the wheel, we want it to grip tightly anyway. And because it's not sliding, there's no frictional heat and you can go any speed you like without melting the rope. Size of wheel to be determined by how much contact you need to prevent slippage.

So now the challenge is to brake the wheel. First approach is something like a conventional disc brake, either in metal or some of the advanced composites they use on expensive cars. If you get a brake company on board (my mate's dad used to be a director of one) then it should be simple to establish whether anything in their catalogue matches the specs required and is small enough to sensibly put on an abseiling rig.

An alternative, if the amount of heat-rejection required exceeds what's sensible with conventional brakes, would be one of those paddle-wheel air brakes used for parachute-jump simulators. Mount one either side of the rope-wheel (two of them means the diameter can be smaller, and avoids a torque load that might set you spinning) and you have your speed limiter. Probably need a disk brake as well for controlling the top and bottom of the descent, but that can be left off for most of the run so won't overheat.

With the disk brake, you could probably mount the whole thing conventionally like any other descender, albeit a bulky one. With the paddle wheel option, you could either keep the rope wheel in front of the climber as normal, with the paddles on shafts out to either side, or you close-couple them to the wheel and suspend the person a few feet below the unit.

The only remaining challenge is how long a rope you can procure :)

Probably best have the abseiler wear a parachute, and a quick-release to jettison all the climbing gear before opening it.

Pete
 
That's a big hole.

If you feed the rope (that's below the abseiler) off a drum from the top at the speed you decend you can keep a loop below the abseiler of a few metres, that way there is no weight below you. I've done this on some shorter abseils when we didn't want to chuck the whole pile of rope off the top. So a feed drum with a brake would work.
 
An interesting thing to do with some good engineering soloutions.

My quiet man story was meeting Brig Gen Paul W Tompson US Army. One of the D-Day bigots, commander of the Assault Training Center at Woolacombe and landed on D-Day at T+6 on Omaha beach.
 
Camelia said:
An interesting thing to do with some good engineering soloutions.

My quiet man story was meeting Brig Gen Paul W Tompson US Army. One of the D-Day bigots, commander of the Assault Training Center at Woolacombe and landed on D-Day at T+6 on Omaha beach.
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My father landed on Sword Beach at 0630 59 years ago yesterday. He still doesn't like to talk about it.
 
Neil_Y said:
That's a big hole.

If you feed the rope (that's below the abseiler) off a drum from the top at the speed you decend you can keep a loop below the abseiler of a few metres, that way there is no weight below you. I've done this on some shorter abseils when we didn't want to chuck the whole pile of rope off the top. So a feed drum with a brake would work.
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That would work, i have abseiled 300ft from a helicoptor (when i used to play soldiers) and you can hardly lift the rope to keep your self going it is so heavy.
 
BobPrell said:
Bigot? What does that mean in this context?

T+6 ? likewise. I know what d-day and h-hour mean.
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Cut from funtrivia:

Every document concerning D-Day was stamped with this word. What was it?

BIGOT. They chose the word BIGOT because they beleived that no-one would go around bragging about something with a classification BIGOT.
Bigots knew the plans for D-day, so very important individuals.

IIRC, T+ refers to the time from the commencement of operations (dunno if this was first landing or the beginning of assaults (eg embarkations, glider and/or para drops)
 
My Grandfather was in the Royal Marines when they formed during the war. He never talked about it and so we know very little about his experiences. He was quite a reserved, quiet man but got me interested in sailing and woodwork. I heard a story from an old friend of his after my grandfather had passed away. He said that they had been at a cruising meet somewhere and had to share a table with a rather brash American fellow. He spent a lot of time blustering about his various sailing exploits while my Grandfather sat quietly. He talked about Norway and a trip there and then asked if my Grandfather had ever been. He replied that he had to which the American said 'probably with some cruise liner or such-like'. Apparently, and completely out of character, my Grandfather said 'No, I arrived in a submarine and made my way ashore at night in a rubber dinghy. I returned after completing my mission which unfortunately required dispatching four enemy with my knife. I have not been back'. He must have been really annoyed as he would never talk like that. The American shut up.
 
One grandfather was a prisoner of war, slave labour in the mines. He was a really small, thin guy, a very snappy dresser. It wasn't until after he died that we pieced together that he must have been taken prisoner at the fall of Tabruk. We have a diary of his last few months as a prisoner. It records how much novacain he had in the prison hospital then how the guards disappeared in the night, and Cossacks arrived next day. The prisoners were taken to the nearest American lines. He wrote that on VE day he had his first beer in 4 years and 'got a little drunk amongst the machine gun fire'!

I knew him as a grocer in Crediton.

My other granddad landed on D day and went through to Berlin as an artillery spotter. He got de-mobbed with a baggy suit and next day was on his bike looking for work.
Again, he never spoke about it and we pieced it together after he died.

I knew him as a plumber, out of work more than in.

Both very quiet men who never talked about it, but then that was the way back then. No boasting, no wearing your heart on your sleeve looking for sympathy, no expectations of compensation, you just got on with the hand life dealt you.
 
prv said:
So now the challenge is to brake the wheel. First approach is something like a conventional disc brake, either in metal or some of the advanced composites they use on expensive cars. If you get a brake company on board (my mate's dad used to be a director of one) then it should be simple to establish whether anything in their catalogue matches the specs required and is small enough to sensibly put on an abseiling rig.
Click to expand...

Honeywell Bremsbelag GmbH Glinde : they make the brakepads for the TGV's.
 
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