Bungy Jump

[bcp]

Quoted in todays SMH (Australian newspaper) is the story about A J Hackett (famous pioneer of the "sport") wanting to launch himself out of a helicopter with a bungy cord that can stretch up to 1.5km.
Plans to do it in Kuala Lumper later this year.....etc.....etc....
What would the effect on the helicopter (which is presumably in a hover at about 2km) be when the bungy cord reaches its limits? Would you need massive collective imput or would you feel very little a the impact would be slow and gradual.
Anyone out there ever been at the controls of a machine while someone jumped with a bungy cord?

[Whirlygig]

http://www.pprune.org/forums/showthread.php?t=252057&highlight=celebrity

One of our number has indeed flown such a mission!

Newtonian physics should tell you that the end of the "bounce" will produce a reaction but I wouldn't have thought it would be that noticeable giving weight of person and weight of twin-engined helicopter.

Cheers

Whirls

[Enzo...TMBPITC]

I believe a BK117 from YSBK did a celeb job like this for Grant Denyer, the former weather man on the Sunrise program, last year sometime as a tandom bungy with some bungy guru. It looked great and I think he did it from around 1500ft.

[GenuineHoverBug]

I wonder what would happen if the cord broke at the jumper's end as he/she bottomed out and the cord was max extended? (Except that the jumper would probably die.)

[205jack]

There's some video footage around somewhere showing a bungy jump something similiar to what is being planned here. Think the jumper went out at around 9000 ft fell some incredible distance bungy broke no chute = dead. The bungy rope rebounded back up through the rotor system of I think a sqirrell.Result pilot and I think maybe 1 pax = dead.Not my idea of fun but then there is always the 1% lunatic element and it is a free world

[GenuineHoverBug]

I would not say that "it is a free world" is the first thing that springs to mind when I think of aviation. There is supposed to be rules, and nowadays there is supposed to be management of risk and safety.

It would be interesting to see the SOP for the job and especially how the associated risk assessment mitigates against an out-of-control bungy cord.

[John Eacott]

I'm intrigued, if not surprised, by the assertion that a bungy cord will come back through the rotors :eek: Also fascinated by 205jack's dissertation, that's certainly one video clip that I've yet to see :rolleyes: The elastic doesn't come even half way back up its length, let alone all the way and far enough to hit the helicopter!!!!!

Whilst AJ intends doing his jump with a new breed of bungy cord, which is tapered to reduce the chance of breakage over such a huge length, I'd like to know the comparative weight of the new style vs. the old. The one that we used, which was about <400ft fully extended, was 40kg, so extrapolating that to a 5,000ft cord would be approaching 500kg of cord on the hook, plus jumper. Half of that would need to be supported at the jumper's end before dispatch from the helicopter, a not inconsiderable task!

Whilst there was absolutely no impact on the helicopter at all when the jumper left my BK, nor when the cord fully extended, I'm not sure that would be the case with half a tonne on the hook; although the stretching of the elastic would minimise the effect, IMHO. Our South African bungy crew did things slightly different to AJ's procedures, and one important flying requirement was to move the helicopter after the jumper left, thus moving the suspension point and inducing a swing when the jumper got to the bottom of the cord. The effect on the helicopter's hover is minimal, but it creates a better "bounce", which dampens out quicker than if it were straight up and down.

When we did the drops that I was flying, I was very impressed at how smooth the effect was on the jumpers, and how little impact it had on the helicopter. If I'd had another approved pilot with me, I'd have had a jump myself :ok: