In article ,
drawnai{at}hotmail.com says...
> I'd give it away for free, just to save lives.
>
> In fact they already exist. Stuntmen use them for falling off high
> buildings.
>
Yes, but stunt men get training and have the balls to jump off
a high building.   People in a burning building certainly have
incentive, but do they have training and enough courage to
use the device without panicking?
> In the world trade centre bombing, practically everyone on the upper
> floors would have got out, had their been a cable harness, consisting
> of several hundred feet of free fall and 200 feet (the last bit
> obviously) of governed decelleration.

How would they have fared (and how would the cables do) going past
the burning floors?

Where does the energy go that represents decelerating a 220 pound
person from   terminal velocity to zero?  Hmmm.  100Kg x 50m/sec
= 5000Kg M/sec or  about 5000Watts (did I get the right conversion
factor).  Does that energy go into the cable, or into heating
the device worn by the jumper?  either way that's a lot of
heat to dissipate?

Who takes the people off the cable that faint on the way down?
>
> In fact, a government could be considered criminally negligent for not
> requiring these things to be installed in very building over a hundred
> feet high.
>
> Compared to the cost of the insurance, at 50 dollars a head for 5000
> people? That's 250,000 dollars. Just one guy in World trade centre 2,
> cost Lloyds 25 million.
>
> There would have been literally no casualties on the non-hit floors.

Have you ever seen such a rig used from 90 floors up--on a windy day?
How much does the cable weigh and how many cables do you need?  One
per floor?  One per 5 floors?   How do you keep the cables (and people)
from higher floors from colliding and tangling with people on lower
floors?

Have you actually tested this idea with a drop of more than 300 feet?
With more than 10 people using the same cable?

Do you have more than one person on the cable at a time?


I think the biggest problem would be getting anyone to manufacture
the system given the potential liabilities involved.   Heck, the
cost of liability insurance represents about 20% of the cost of
a simple step ladder?   What would the proportion be for this device?

Sounds like an interesting idea---if you have the engineering worked
out properly.


Mark Borgerson




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