The Big Flying Fox
Well, this isn't science as much as Civil Engineering. back in the early 1970's, my BFF Wayne had this bright idea. We had already build ourselves a treehouse in a big gum tree in the side yard of his place, maybe 15 feet high. Climbing up and down the ladder was a pain, so Wayne decided that the easy way down was to build a flying fox, from treehouse platform level to the ground. All we needed was a suitable rope, with a pulley on it.

So, we scrounged the anchor line from his father's fishing dinghy - about 40 feet of wire rope, with an anchor on one end. This anchor was not a substantial affair- just a four pronged device made from bent (mild) steel. We put the anchor through the fork of a convenient tree, maybe 30 feetout from the treehouse. The other end was attached to the trunk of the tree a few feet above the treehouse platform, and a suitable pulley put on the wire. We made a seat, attached that to the pulley, and we were ready to go.

Wayne, as chief engineer, tested if first. Woosh - he went zooming down the flying fox, and landed gracefully on the ground below. I pulled the "fox" back to the treehouse level, and then it was my turn. More fun that sex! So it was Wayne's turn again. As soon as he pushed off from the platform, ARRRRGH!!!! and CRASH as the wire rope pulled away from the tree at the far end, and Wayne flew like a brick, straight down at a great rate of knots.

Our weight (as little as it was) was too much for the mild steel boat anchor - it had pulled out from between the tree trunks, and what was originally four curved flukes, designed to hold his father's fishing dinghy at anchor were now straight. The rest of the afternoon was spent re-bending the anchor back into a shape resembling its original appearance, before his father came home from work and saw what we had done.

Needless to say, both of us were misguided enough to initially attempt careers in engineering....
(Maclir, Wed 15 Aug 2012, 16:28, Reply)