Basejumper.com - archive

you can jump w/ winds down the wire....

I could just without my rig too but its not to smart. j/k

I've only got 11 jumps so I'm playing it safe. From what I have learned winds down the wire is not to smart.....

Wind down the wire is the 2nd most dangerous way to jump a tower (ruling out headwind jumps, which ought to be "no go" from a safety standpoint). Zero wind is the only condition that is more dangerous.

If you are willing to jump in zero wind, you ought to be willing to take wind down the wire. If you're not willing to jump in zero wind, because you want the wind to help make things safer for you, then you probably shouldn't jump in wind down the wire, either.

More discussion (and some diagrams) can be found on the BASEWiki Antenna page.

Right that is exactly what I have learned. I will not jump in zero wind, and until I have a lot more experience I am not willing to jump with wind down the lines either. The farthest I have gone is about 30-35 off center. I am also doing phone ground crew jumps at the moment too so having near perfect conditions makes me feel better also.

Coco

Edited to add: I've have made like 3 jumps in the last two weeks or so and have climb at about 8 times. I'd rather climb down than jump in bad conditions and hope for the best. "Live to die another day."

I got a ? for ya Tom (or other). I remember on another thread a while back to you were talking about how you had a PC blow over your head from high winds. At what (tail) wind speed would you says this problem BEGINS to become an issue?

Coco

Edited to add: Also I'm sure delay and PC size makes a difference too correct?

my buddy and I got a nice little 364 ET a couple hours pre turkey day, close enough. zero moonlight, but no biggie.

Well, I'm not really comfortable with that at the moment so lets say I'm doing a jump from 540 and/or 900 (no tracking) and openning at about 200-250 feet (typical where I make my measurment and judgement for the jump). At what wind speed would you begin to find the issue of a PC getting blown over your head.

Coco

I split this off the "Turkey Day Jumps" thread.

Thanks Tom!! I was actually gonna ask about that. Now I just need some reply's.
Coco

In theory, this begins to become an issue when the tailwind exceeds your downward fall rate and the speed at which you pitch the PC.

In practice, I've only had this happen with very high tailwinds. Maybe 30+ mph at the time of deployment.

Basically, this is a 3 dimensional vector addition problem. You add the speed of the wind (forward, presumably), to the speed the PC is moving (sideways), to your fall rate (relative wind up, as the PC sees it). The faster you are falling, the more vertical component, and the faster you pitch the more sideways component. The trick is basically to be sure that you take enough delay so that the wind blowing the PC up is enough to make the PC actually move up. If you pitch a PC while you are not falling (say you do a go and throw, or just pitch while standing in the parking lot, to see what will happen), the PC will move across (relative to you). If you pitch while falling at terminal, the PC will move upward (again, relative to you) very quickly.

I'm not sure that PC size makes much difference. Delay is a very important factor. Taking enough delay so that your relative wind speed exceeds the absolute wind speed will pretty much eliminate this problem (and several others, actually).

Awesome!!! Thank you very much Tom!

Coco

 

Well, I'm not really comfortable with that at the moment so lets say I'm doing a jump from 540 and/or 900 (no tracking) and openning at about 200-250 feet (typical where I make my measurment and judgement for the jump). At what wind speed would you begin to find the issue of a PC getting blown over your head.

Coco


I would venture to say and i could be wrong, but almost everyone ever hung up on a wire , were jumping at the heights you are talking about. The middle heights of towers are the most dangerous . IN any thing other than perfect winds you are taking a huge chance of hitting a wire. You are very close to the tower on opening with plenty of wires to hit below. Not just 180's but also consider line twists. I know of one incident where the person had twists and actualy flew through the wire sets twice and was fortunate not to hit either one. 300ft to about 1000ft is a dangerous place on a tower. You really have to have the right winds.

Right Right, good points! Yea, I’m not exactly sure but I believe the inside platform at where we measure winds speeds and direction for opening is at ~250 feet. This is info passed on from previous experienced jumpers who had tools that found the heights (one had a watch I know for a fact). I just received my wind meter the other day and it has an altitude (not perfect but close) function so I will confirm platforms and deployment heights. I’ll also see where on the A the lower guy wire is attached.

Coco

i´ll be smart to say jumping INTO a wind UP the wire,dressed like a woman would be the most dangerus thing to do from an A,but hey what do i know about A´s?

Hello from the 2 danes getting a few beers(Nikolaj and Faber).

I've heard that animal prints actually help...