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last evening my buddy and I went up an 'A' that is 315 ft high. The winds on the ground were not more than 0-4mph. At 100ft it was still about 4mph but past 200ft it started picking up. At the top it was probably in the 18-20mph range. The landing area on this jump is huge enough not be to an issue. If we had jumped we would have had the winds coming from directly behind us hence pushing us away from the 'A'. We were going to do a 1 sec delay, hand held, tail gate, slider down, 47"PC. Our concern centered more around the effect of 18-20mph winds on the pilot chute throw, the pack job extraction on opening, canopy inflation, turbulance due to wind shear around 200 ft where the winds seemed to start picking up.

Since we were not certain about the impact of such a wind condition we decided to climb down and try and get a better understanding of it first. I would love to hear from the more experienced on the affect of 18mph winds on such a jump. Is 18mph considered strong, border line or not a concern for an 'A' (it was coming from the right direction) Again, the landing area is a big open field so being carried out over it due to the strong wind wouldn't be much of an issue.

I've heard stories about Dwain doing floaters off an antenna in 30 mph winds. He opened facing the antenna and was just blown backwards away from the antenna.

As long as the landing area still allows a nice setup, preferably landing into the wind, I would imagine jumping in 18 mph is fine.

See BASE WIKI on antennas.

This is actually very commonly done on one of the regular Northern California objects.

I don't think that 18-20 is enough to do this, but;

I've had strong tailwinds at exit (30+) blow a stowed PC in front of me, under my arm, resulting in a bridle wrapped around my arm. Under these conditions, you might want to go hand held, and pitch in an upward direction, to reduce this concern.




With very low airspeed, it's likely that the wind will govern your opening heading. I've been on loads in 35+ tailwinds where every jumper had exactly the same offheading opening--directly into the wind. If you have a strong tailwind, and a short delay, be prepared for a 180 (or whatever opening is directly into the wind). A longer delay will generally help avoid this. As a rule of thumb, if your fall rate (relative wind) is less than the absolute tailwind, expect the absolute wind to be the governing factor on your opening. Of course, with a tailwind that strong, a 180 isn't usually a big deal, because you are being blown away from the object quite quickly.




That's a big point that many people miss out on. Good on you for thinking about it. Any time the wind changes, there is turbulence. The greater the magnitude of the change, the greater the turbulence. If there is a sharp boundary (as in your case) expect greater turbulence. One strategy for dealing with this is to take a deeper delay (and hence open below the turbulence). That's psychologically easier, but in reality, I don't think it matters much. BASE canopies recover from turbulence so fast that the only turbulence that's really dangerous is too low to open underneath anyway. In this case, my guess is that you would have passed through the turbulence and had time to recover before landing.




18 mph probably isn't too much of a concern on a site like that. I can't say for sure without actually seeing it, though.

I think you made the right choice. You're both still walking around without crutches, and the 'A' will still be there the next time you go.

I'm pretty sure the BASE Wiki article you are referring him to has no information about his specific questions, at this point.

To all; nudge nudge...

Thanks. This really helps.

how about a side wind, 15-30 MPH, 1-2 sec delay?
that would be applicable to an A with 120 sector guidewires with the wing blowing exactly down the wire. IMHO the optimal exit direction is 90 degrees to the wind direction into either downwind sector. any thoughts on that?

15-30 is a pretty big range. So is 1-2. I'd say that a 2 second delay with 15 mph wind is a whole lot better than a 1 second delay with 30.

1 second delay with 30 mph wind, I'd guess you're going to get an offheading into the wind.



If you know, for certain, that the wind speed exceeds your canopy's forward speed, I don't think you need to stop at 90. Maximum separation from the obstacle you might strike (the tower or the downwind wire) is the goal. If the wind guarantees that you will not strike the upwind wire, you can pretty much exit as close to it as you want.

Can you explain your reasoning on the 90 degrees? I'm thinking it through, and it looks like maximum separation is achieved by exiting as close to the upwind wire (120 degrees) as possible, but I might be missing something.

it is just like swimming through a current, there is no point in fighting it if you want is to get across. Exiting more into the wind will result in a wider safe sector of possible off-heading openings but the separation from the antenna and the downdwind wire will be less.

I agree with the 90 degrees -- ref: this post (crayolas and all)

Basically, a) 90 deg puts you as far as possible from the down-wind wires -- 110 seems further from the down-wind wires, but it's really not, since the wind will be carying you past where they start in short order -- so an opening facing directly at the plane of the down-wind wires puts you closer to striking them with a 110 deg exit than with a 90 deg exit.
b) the diagram in the above post shows that with the right opening you can hit the up-wind wire even if the wind-speed equals (or even slightly exceeds) your canopy speed.

I used to have a good freestander that I would exit facing it and if the winds cut off I would just turn to whichever side it opened and fly past the side to landing but I jumped facing away and had it collapse on me at a 100' from the wind shear turbulance. And just like Tom, I've had a PC come back at me with the wind.
However, on higher jumps, I often exit normal and turn to track into the tower on high wind days. Almost every jump is like this in the fall for me, here.
SOmething to think about. Both floater exits on a low freestander and tracking up to the steal on a tall tower go against what you learn early and are a bit trippy at first but logically make sense. That is, if you're going to exit on a high wind day in the first place. That leaves some room for thought in itself. I commend the climbing down to ask.

I was told that on high A's the wind changes direction just a bit from the ground winds due to some type of effect? I am not sure if it was (sp) corolioas(/sp?) or the spin of the earth or something else.

In terms of expectation of winds aloft, the coriollis effect can turn LIGHT winds from their ground heading. If they are borderline on the ground, they could be down the wire aloft...Strong winds carry too much momentum to be affected, in general coriollis doesnt play a major part in Antenna evaluation. Dropping little pieces of spit or paper at various altitudes as you climb, to be intimately aware of what the wind is doing, in order to form a mental wind profile of your antenna on a jump night, is a vastly more important tool. Be aware of the forecast, be very aware of what winds are doing on the ground and at expected opening altitude, and be mindful of whether a wind-line (or wind shear) exists. (Strong winds aloft dropping off sharply nearer the ground to light or calm winds; the canopy may dive to regain a speed necessary to fly if the canopy crosses a wind line, from strong wind to light wind. Your accuracy in landing in a given spot will be influenced by the existence of this effect, and if it occurs closer to the ground, you could lose significant altitude rapidly when you may not have it available. Particularly with you big guys





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Thanks I just needed a refresher on that...Hey what do you mean you big guys?

Well, I thought Aiello probably needed a refresher. Im pretty sure he hasnt been on an antenna in years...


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The change in direction is mostly due to the proximity of the ground, which slows the air down. Being slower, the air is less affected by the coriolis effect, and thus tends to drift in a more direct manner from high pressure to low pressure.

When observing the ground wind, one can theorically expect the wind aloft (~1000'/2000') to turn 30° to the right and increase by 50%.

This doesn't take local particularities in account.

Also, tailwind openings will generally be slower, less on-heading, and have a higher incidence of line-overs...

I remember somewhat dis-agreeing with this, but now I understand your logic. the OPENING (bottom skin inflation) will be about the same as no airspeed or head wind (what I was thinking about [opening only considering bottom skin inflation], because this inflation is based on overall airspeed, not one with a vector of gravity and parachute forward airspeed involved) but the parachute inflation and transition to 'flight' [in tailwind openings] is considerably slower due to the horizontal inertia required to overcome the additional 15kt (or whatever) speed. examples-
from bridge
-no wind, fall off, parachtue opens on heading and needs to accelerate jumper 15mph to achieve forward 'flight'
-tail wind, 15mph same thing, only the parachute needs to accelerate jumper to 30mph before the parachute is in stable flight
-head wind, 15mph, parachute opens stationary because horizontal inertia relative to surrounding airmass is already achieved

of course this is all elementary, but good to think about when considering floaters.

IF this 15mph tailwind deployment were to experience a 180 before line stretch of slider down opening, (almost all slider down 180s occur before line stretch or inflation of any kind), then the airspeed needed to maintain forward flight would already be achieved, making the parachute 'open and flying' into the wind LONG before it would happen were it on heading, downwind.

also, the lineover point is a good one, but line overs do not happen if the proper methods are used. (two bites primary stow, good solid tail/tapegate) It is terrifying that some still do not use the tail/tapegate slider up. with shallow brake settings this, high packjob-airspeed shears, the lineover is much more likely to happen slider up terminal.

Listen up new CO crew
The A-floater method is money, and is safer than opening downwind for slider down. but if it is strong enough to do a floater, re-consider jumping.

freefall speed:

1 sec = 20 mph
2 sec = 40 mph
3 sec = 60 mph

this regularity changes beyond 3 seconds.

total wind speed from vectorial addition ~ 28 mph. not a big deal.

so a 20 mph wind at exit won't make that much of a difference. if the winds are much stronger than this, you might have a downplane on opening.

if the winds are pretty strong, take a longer delay to dominate the horizontal wind with vertical wind.

the canopy will generally open downwind (primarily for mesh slider up). for slider down with a significant crosswind, it will open downwind or sometimes upwind.

you are making the same mistake I did. a fully inflated and flying parachute does not mean that it is a stable parachute/flying machine.

for slider down (where 99% of the time the jumper has not met an equilibrium with surrounding air mass as happens with wingsuits and long delays) the soul means for meeting equilibrium with the surrounding air mass is aerodynamic influences of the parachute, not the jumpers body.

we are fixed object jumping, meaning we enter an air mass in respects to the objects' airspeed.

of course, you are partially correct, after 3 seconds from 500' slider down in 20kt tailwind, the difference is minimal but still remarkable. but a 0-1 sec with 20kt tailwind matters a LOT.

Calvin you know your shit , I can see that....but whaaaaat ??
I'll punt it out there that its far more common in Europe and its surrounds to jump slider up without a tailgate.
If a line over was a 'sure thing' with a slider up without a tailgate ....whats been happening over here since, well forever ??
...it happens ...but I'll say its rare

Personally I dont tailgate slider up....and personally I dont think its necessary with good packing methods...
so convince me /us over here we are doing it wrong..?

This doesn't make that much sense to me.

The difference between zero seconds and 1 second is huge in the opening response. Please resummarize your statement to simplify what you mean.

thanks

I was being dramatic, the primary stow and the slider provide ample tail inversion protection, but I use the tapegate for every jump, unpacked or packed, slider on or off. I also pack with the tail buried.

mainly I can see a major problem with a slider up terminal packjob, deployed at ternimnal, with a tailpocket hesitation, and the tail being loose and free to wrap up over the top of the canopy (lineover)
the tapegate slider up, as well as the tail buried packjob greatly decreases this risk.

I rarely hear of lineovers anymore. starting BASE it seemed like a somewhat freak occurrence but still happened enough for a lot of people to have the experience dealing with one. after over 1000 parachute deployments (sky/BASE/PG) I have never had or seen anything even remotely close to a lineover. (other than a few noobs doing unpacked RETARDED shit at the perrine and spinning in, but that might have been intentional)

I always use tape (no tailgate). Slider up, slider down. Not to say clean packing doesn't works wonders, and I think you may be right in saying that it will help to prevent line-overs, but $2 for tape, 10 seconds of extra rigging. I say why not. I have never had a line over in over 300 jumps (knock on wood, or something) and I personally think the tape has had something to do with this.

Oh, yeah, and Calvin knows nothing.

Neither have I...and I dont use any type of tailgate slider up....
So....what are we saying here?

Well, not to be rude, but if you read what I posted, I said, "why not use masking tape". It's not hard to use, and it's inexpensive. You have stated that you have 85 BASE jumps, which is some experience, but very limited (as is my mere 300). You have only been jumping one year, unless your info isn't up to date, which isn't very long to be doing much of anything. It would be very reasonable to say that you have just gotten lucky so far. I am not saying that this is the case, but I think with your limited experience, to be saying you are sure that you won't have a line-over without using masking tape is very presumptuous, arrogant even. I am not sure that using tape prevents them, but I know it doesn't hurt. Please understand I mean you no disrespect.
Adam

Not to be rude either but to to me one answer to your question is in Will's (inzite) post in this thread http://www.basejumper.com/...um.cgi?post=2893262;.

At Kjerag this year I had a tape malfunction on a slider up jump. Upon opening the tape (four wraps) didn't break, keeping the rear of the canopy bowtied for about two seconds. Luckily, after those two seconds, the tape descended the steering lines before stopping about a half meter above the slider.

Might be useful to read the whole post, in his post Will says he changed to using tailgate in slider up jumps as well. Personally I never use tg / tape / anything SU and neither does any of the people I regularly jump with. Among the group I jump with I estimate that we have together total of over 1000 SU BASE deployments (without tape / TG) and have witnessed 0 line overs. Now that does not prove that line overs do not happen, maybe we only have been lucky so far, but here in Europe it seems pretty common to not use TG/tape slider up (actually apart from Will I do not know personally single one European BASE jumper who use tape/TG SU). So if the risk of having line over without TG/tape SU would be very severe, I'd assume that we would have a handful of those every summer this side of the pond. Last but not least I also use WLO toggles as a backup in case if I ever experience a steering line induced line over.

My profile (was) out of date.
Im somewhere in the 300+ range
And I think I said....I know they happen but are pretty rare ( that's a bit different to saying I wont have one not using su tailgate ;) )

Im really interested to find out if there is any valid reason for using one ....in comparison with events/near misses/chances of lines overs (on no tailgated su packjobs) vs the same on tailgated su packjobs
....and am just asking for more info to be convinced by those that do tailgate their su packjobs
:)

don't use tape.

Calvin mentioned line overs in the early days of BASE. They happened all the time. I saw a two way that resulted in both of them having line overs. So, techniques were developed using systems very very similar to the tailgate. Other techniques involved packing the tail into itself, developed by Carl Boenish, BASE 74, and BASE 175, which greatly reduced line overs. Later generations of jumpers either didn't learn these techniques or just were too lazy.

For slider up, line overs are just very rare. WLO toggles are the best option for this IMHO. Doing anything above the slider or with the slider is asking for trouble. I developed a trapezoidal slider in 1997 by tacking the rear of my slider to reduce its rear length by 1 inch and I had a severe malfunction that resulted in my near death - a severely shattered femur while laying on top of a Texas fire ant nest. The best way to control the tail I think is with a slider gate.

Good advice thanks! (from a NEW Co jumper!)

Why not? curious about the negative points of above slider packed modifications you mentioned also. I use the tapegate every jump like I said, packed or unpacked, slider up or down. as well as for paragliding.

I played with that one on a few jumps, the idea seems great to simplify packing but lineovers happen when the tail lines become loaded before the rest of the lines, if the tail lines get loaded with a slider gate, it pops off because the slider gate 'opens' instantly with any load because it is a rubber band decreasing the length of the lines, like a 'mini primary stow'. so any load on them before the rest of the canopy has line tension [tail inversion] pops the slider gate off, negating it. with a tapegate and the correct wraps, it requires lateral load to break, thus more adequately preventing lines from escaping pre-maturely. a regular tailgate works the same as tape, but we all know the bad sides of slier up tailgate, with large mesh sliders at least.

I kinda regret posting that now, the floater is an advanced maneuver that should be done only by people who understand the theories involved in it. we have high winds here a lot, and the floater is reserved for special cases and special sites. if the wind is high, climb down.

Yeah that's the good advice I was talking about . . ."If It's strong enough to do a floater, re-consider jumping".

(I climb down alot)

Will respond when I have more time to clarify the issue and to think about what you've composed. Much too busy for the next few days to dedicate to base thoughts.

Tape is humidity sensitive and can be time sensitive. The difference in masking tape behavior in New York compared to the gulf coast is very significant. When I lived on Long Island, masking tape acted great. When I came back to Houston, the stuff leaked glue all over the place.

Just one thought to throw into the mix from my swiss-cheese of a mind:

How many of you regularly see (from the jumper's POV) your slider down openings as they happen? Speaking for myself, particularly when I'm jumping a camera, I try to keep my head squared up on my shoulders for each slider down/off opening I have. With this being the case, how many of our openings, particularly night jumps without clear video, may have had partial/self-clearing lineovers without our knowledge?

I for one have never had a proper fucked line over, but I have seen MANY openings both s/u and off, with partial/self clearing lineovers that the pilot in most cases never even knew they had. We should remind ourselves that what we *think* we experience is not always the same as what actually happens.
Still, IMO, whichever packing method gives us each warm fuzzies in terms of l/o protection, I agree with what Hecker said earlier, that our best bets are to huck responsibly, and don't let our desire to jump outweigh our desire to live. Altitude and longer delays are our friends in higher winds.

PS:
$0.02 - I for one have been very happy with my packing methods in the past [kow] and for the record I'm also a fan of the (sticky side out) tape-gate for both slider up and slider off jumps alike.

cheers!
pope

Of course we are BASE jumping, and to everyone their own.

I have jumped in very different saturated air areas, (Hawaii waterfalls, WI, MN, bridge day wetness, SoCal, Desert Utah, mostly in dry Colorado) and never seen a change in my sticky side out blue painters tape, I have gone through an entire 2 rolls now. I have jumped fairly wet potato post water landing packjobs with tape, did not notice a change. I at one point bought green high adhesion painters tape, and found the easy way it was black death.

what tape are you using/where using did you make these conclusions with?
a jumper did a water saturated test (tear resistance strength test, non jumping) to find minimal change in the medium-adhesion blue tape I use, but VERY dangerous results on high adhesion masking tape.

regular masking tape. not the blue tape. will pm more details later.

it's no big deal if packed rig is used within some reasonable time.

Lets make up a poll. What is the best brand/color of masking tape?

I got a little paranoid about masking tape getting stretchy and not tearing, so I tried a couple different things. Didn't take much thought, but here are two ways that you can have a tape tailgate, and not have to worry about it.

- Take some paper. Any kind of paper. Copy paper works great! Tear it into strips so that it looks like masking tape. Wrap it around your tailgate friendly lines, and use some tape to tape it down. Box tape, duct tape, or even masking tape will work, as long as you don't wrap the tape around, and there is still the weak link as the paper. I would imagine that the paper will not cause you to go in because it won't tear when humid. PM me and I will make one up and send you some pictures.

- Go to Best Buy or Staples, and get some printer labels that are made in the shape of VCR labels. The long and narrow kind. Made of paper, with adhesive. I used to use this when I was in Hawaii, half because I was concerned, and half because I smirked every time I thought about a little paper tailgate from the dz blowing in the street. Lets not get into if this can cause a tailgate hangup.

I was fortunate early in my jumps to spend a bit of time up in Twin, getting ultra current on bridge jumping with BASE gear. I think that not often, but on occasion, in night jumps, what might be perceived as a 90/180/strange opening, might in fact be a slider-down line-over that clears by itself, very quickly. I am a meticulous packer, of course using tailgates, with two videos from the Perrine that, after watching over and over, could only be a self clearing, slider down lineovers. They felt strange on opening, resulted in 45 offheadings, but there was something strange on video from above. I also spent several days in Moab with my camera pointed backwards to get some new camera angles, and watching lines as they come out to inflation is simply scary. Just saying.

Oh, by the way, the last time that this topic came up, I went to the Home Depot and bought every type of masking tape they sold, and did some BASE specific tests, including running the tape under the water faucet. The results were described as scientifically as possible, I think its in the technical forum, if that even exists on this dorkjumper.com anymore.

I feel pretty confident with my BASE gear if the most important topic of conversation worldwide keeps coming back to what color of masking tape works.