Basejumper.com - archive

 

Wow, I thought it was just me! This has happen to me twice with my BJ 260. Once at TF slider up and once when it took it on a skydive for a demo. Send me a PM and we can talked further about what I think happened.

Mark K

The amount of opening surge that a canopy experiences at opening is mostly a function of the brake setting relative to the jumpers body weight (also, of course the wind, and the altitude, and the temperature, and about a dozen other things).

Factory brake settings are basically just the manufacturers best guess at a good brake setting for the recommended wingloading (jumper weight) and "average" opening conditions. If you change any of the relevant variables (gain or lose weight, jump at a higher or lower altitude than normal, jump in hotter or colder temperatures) your canopy speed at opening (and hence opening surge) will change.

If you want your canopy to have less forward speed at opening, I'd recommend installing a deeper brake setting.

Be aware that using an overly deep setting can result in deployment stall (the canopy cannot start flying, and hence stalls immediately), which can result in backsurge at opening, or (worse) when slider up, a failure of the slider to come down.

On most slider up up jumps, opening surge isn't a real problem, because you have adequate time to track away from the object. On the jumps you are doing (8 to 9 second delays), I wouldn't worry about it. If you're jumping towers (likely given your location) you should be jumping with a tailwind (pushing you away from the object), making this even less of an issue.

>>BLACKJACK theories anyone?<<

Never hit on seventeen . . .

NickD

The manufacturers would prefer that one opens not in a stall/surge fwd/stall/surge fwd repeat mode. Dialing in your canopy is recommended. CR has some articles on this.
Take care,
space

Interesting question after over 50 basejumps.

dumb ass remark, even for a non jumper.

Or, a very interesting observation.
Take care,
space

 

Any changes in conditions? Different temperatures, for example? I'm assuming the same object?



An opening with more surge will almost always feel "harder" (aside from surge in the same direction as your track).

What we perceive as a "hard" opening is a change in the body's velocity (meaning speed and direction). Sudden deceleration is perceived as "hard" to some extent, but so (equally) is a change in direction. So, if you are falling straight down, and then your canopy surges to one side of your fall line (forward, backward, to the side, it doesn't matter), you will feel that the opening is "hard".

hmm...

I jump my BJ 260 slider up a lot, anywhere from 450-2000' 0-20 sec delays. wingsuit also. maybe i know what you are talking about?
i would venture to say, nothing at all changed inside your parachute, only your perception has changed.

the only times I really notice the surge effect is when I am on the toggles instantly, and I try to correct heading even as the slider is coming down. this is in DBS and SBS.

what were the winds? direction, velocity? One jump in 50 doesn't seem like that big of deal, occasionally random things happen...

i noticed it from the gruond jumping with epibase. i have never seen a canopy surge that dramatically on opening, as if the brakes were not set or were far too shallow.