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Hi,

I'm planning a new jump and I need some advice. It's a 220 foot building that I would like to static line.

The first question is about backsurge and having a solid object behind me. On my deepest brake-setting doing static line jumps from our 180 foot bridge, I occasionally have a backsurge that puts me halfway underneath the bridge. Obviously on a building jump that could wake up some people when you smash into their windows.

I'm planning on jumping in zero winds, which will avoid the headwind pushback. I'm also planning on using my middle brake settings which will give me a bit more forward speed. Finally, I launch very head high and don't pop my toggles until well clear from the building, to avoid a pendulum effect.

Does anybody have any other thoughts on how to avoid hitting the building, even when you do have a perfect on heading opening?

Secondly, I'd like some thoughts on the static-line attachment point. I attached a cross section of the exit point. I can leave gear on the building and retrieve it later no problem. I have free and legal access to the roof.

So the green line is the direction of the jump. The red is a railing. The railing is approximately seven feet away from the edge of the building. I can attach a static line, an extra bridle, or something else at either one of the two blue crosses.

My worry is where the yellow cross is. My original plan was to attach a second short bridle to gain the distance to the edge. Then attach a static line to that and to my own bridle. Now imagine a person jumps, the bridle will be hovering above the edge, then suddenly catch on the edge and create a heavy shockload. I'm not sure what this is going to do with the static-line or the general predictability of the opening. I am considering to drape a few towels over the edge where the bridle can slap on to soften the blow. Sounds like a sub-ideal solution to me though.

Does anybody else have better ideas? I could use a longer bridle and make sure it is already draped over the edge (in contact with) before I jump, so the shockload is less. This will put my canopy opening a lot lower though.

Anyway, I hope this message makes sense.

Cheers,

Jaap

Wouldnt it be best to use shallow brake settings on this. As the chances off an offheading are down considerably seeing you are static lining it. less surge when you pop brakes. how is the landing area?

i dont think your shockloading concerns would really present a problem the force needed to open you container is very small. and all tension should be off it by the time that edge comes into play.

im just a beginner though. i wouldnt really listen to me or my advice =)

Landing area is intermediate by my standards. Onheading opening makes it easy as cake. Slight offheadings make it a heads-up flight pattern. Gross offheadings make it rather interesting but survivable.


I'm not worried about my container not opening. Imagine what happens when you stand on the edge and you have a bridle dangling in lose air between you and the attachment point. Now you jump. The bridle is freely moving through the air, and all of a sudden it slaps onto the corner of the building, sending a shockwave in both directions. I'm not too worried about the bridle braking, but wondering if my breakcord could prematurely fuck something up, or if the shockwave could pop my pins too violently, creating an uneven extraction of the canopy.

Perhaps I'm just being too paranoid, but better safe than sorry.

Yeah what i ment is..

i dont think there would ever be much force on the bridle for it to become a problem if it even could be one. hitting the edge to fuck up your break cord there would have to be a bit of loading on the bridle. but your canopy should already be extracted before that loading is high enough to come into play.

you dont have to worry about all that if you free fall it.
Its just what i wiuld do
Ryan

Shallow brakes sounds like a good idea to me.

depending on your canopy and pc selection shallow brakes is not ideal for this kind of jump...if you go shallow brakes you are likely to have an unflyable canopy for most of the descent due to poor pressurisation..ask Mac about TCs jump from the house .i would get your battle gear on, get the bubble wrap down your trousers and if you are jumping a 240 use a ZP 42" with a half to 1 second delay...this will give you around 6 seconds of usable canopy time...definitely go with deep brakes.either that or get a short line PCA...just my two cents...

Yeah, that's why I have a middle brake setting. I've experimented with both the middle and the deepest one from the 180 foot span, and I liked the inflation and flight characteristics on the middle one better.

My shallow slider-up setting is definitely too shallow.



I wear my battle gear regardless.


42 inch from 240 feet? I would argue that 46 is the default choice. 42 will probably work, but I'd never recommend it.


Anyway, aside from having a personal harddeck for not freefalling below 250 (currently tested up to 270), this particular object has an extra problem. 150 feet below the exit point is an extra roofdeck extending out. So free-falling is not an option. I need to be open relatively high to make sure I clear this roofdeck and land below on the streets.

you are more likely to over delay with a 46 due to PC inflation time on that height...the canopy isnt that big that you need a 46 to drag it out and based on my limited experience including jumps from240 225 215 and 200 with both sizes the 42" is the better option.

CR did some comparison test years ago between the two sizes for smaller 190-240 size Mojos and i believe they found no problem with the 42ZP at lower altitudes.

Maybe Adam can chime in here or tom for that matter..

I personally have never seen this. I have seen many canopies go into full flight sooner with shallow brakes instead of deep brakes. If the canopy has bottom skin air inlets, these differences should not be too noticable. Confirm this your canopy manufacturers and other experienced jumpers before proceeding.


Qouting: depending on your canopy and pc selection shallow brakes is not ideal for this kind of jump...if you go shallow brakes you are likely to have an unflyable canopy for most of the descent due to poor pressurisation..ask Mac about TCs jump from the house .i would get your battle gear on, get the bubble wrap down your trousers and if you are jumping a 240 use a ZP 42" with a half to 1 second delay...this will give you around 6 seconds of usable canopy time...definitely go with deep brakes.either that or get a short line PCA...just my two cents...

Very interesting. I was aware that the differences between a 42 and 46 were neglectible in that a 46 takes longer to inflate but then pulls faster, so the two effects cancel each other out.

The last time this got brought up was in the context of a 300 feet jump, where most people argued that the 46 was their default for hand-held, but they'd happily take a 42. I've taken both 46 and 42 from 300 feet. Stowed, I would prefer the 42, but I rarely go stowed from that altitude anyway, so my default was always 46.

Have we now gotten to the point where some people recommend doing away with the 46 all together unless for ultra ultra low freefall (the type where you pitch the pilotchute upwards), static-line backups, and PCAs? Is the 42 really versatile enough to work from 200 feet upwards to 4 second slider down delays?

I'd love for other experienced jumpers to chime in on this one. It's a bit of a thread-drift, but very interesting. What a difference with five years ago. Just look at the BR delay chart to see how time has changed.

In general, my experience is in line with Sean's. I've found that smaller PC's tend to be less prone to hesitation, and that it's a PC hesitation, rather than a slightly slower extraction, that will really do you in.

Note that I do not recommend experimenting with this at low altitude, and that I don't recommend that anyone actually use any PC size that's not the recommended size for the delay (from the manufacturers chart). If you want to play this game, be sure that you have formed your own opinion, and that you take sole responsibility for any outcome.

Are you worried about the corner of the building cutting your static line? No, it's not razor sharp, but if it has a very small radius that wouldn't be good for the static line, would it?

One thing iv always wondered. most building jumps i see is always off the side of a building. where anything over 90degree's offheading would start to make you going in the direction of the building..

Do many people lauch off the corner of a building.. it would seem to me like it would give you more offheading leway.

We were jumping a 240ft B a couple of years ago and TC decided to go for the shallow break setting on his unvented canopy. On opening he had a 120ish off heading (not great as we were jumping in the middle of the face) and the canopy just dove then rocked back and continued to rock back and forward and just dumped him in hard at the base of the B onto concrete, there was hardly any forward movement at all. He did not release his toggles during this.

This is only from my view on top.

With the 42 v 46, like Sean and Tom, I agree that a 42 will give more consistant inflation. I have taken a 42 from 225, 220 and 210 with a 266 and found no problem. I witnessed a PC tow on a go n throw with a 46, but luckily he was jumping from about 340ft.

We all regularly jump 42's below 300ft (or at least I used to before I returned back from injury) and even with my 280 (265 MDV) I see no problem, although lower than 250 I would now probably opt for a 46 now I jump a bigger canopy just to keep my mind happy, but ensure I fold it in a way to start inflating the PC whilst in my hand.......

Jaap,

Don't go shallow, really.

I have three brake settings on my ACE: the factory swallow, the factory deep and the super deep. With the super deep I get very little to no forward speed but they are not so deep to give me an awful back-surge.

If I had to to this jump I'd go with the factory deep.
I don't know about your set up but I'd not go with shallow stuff of a 220' object. As per BASE831 example, you get an off heading and you'll be cruising like a mother.

As for the 46 vs 42 debate: I saw some hesitations at the potato with people using 46 and very short delays (<1.5 sec).

I have never had a PC hesitation with my 46 but...
I am working now on a 42" BASE drogue...

I forgot,

Can you find someone to PCA you? I think it's the best course of action for this jump.

If you want to go S/L I would build a 9' carry on S/L and use that.

Later.

So shouldn't the subject line read: ?

no...

Fair enough. If I jump a 600ft cliff with a 1400 foot talus and canopy ride, I don't call it a 2000ft jump either. So you have a point.

Oh well...

I think it's an important distinction. You look down at the parking lot and it's hard not to think of yourself as being that high up. And, really, if you do get canopy in time and on-heading, you do have that much more time to get on your toggles and set up for landing, right? Right...
..."if"...

Oh trust me, I've taken the roofdeck and the 150 feet issue well into account. That wasn't really the point of the original post though. My question was about the edge of the building and it creating an extra point of contact between my pins and the bridle attachment point.

Only when people suggested that I freefall it, was it necessary to bring up the 150 foot issue.

I very much agree that it creates an extra set of issues I have to deal with.

Jaap, how wide is the roof below?

PCA still sounds to be the best option.

About as wide as the building itself. Yeah, PCA sounds like a better option too. The PCAer could even tie himself off to the railing to make sure he doesn't fall. The people that I'll let PCA me would like to jump it themselves too though, so unless I find some groundcrew I can trust to PCA, I'm still going to research the static line option.

A figure in feet or meters?

A S/L vs PCA should only add 9' to the deployment.

I guess you have to watch the jumpers who you'll PCA and see how they clear the lower roof and then make up your mind if the S/L option is duable.

Again I would construct a 9' carry on S/L that attaches to the railing so that the briddle and PC don't get damaged by the edge of the B.

Good luck with it!

, about 60 feet wide, extending about 40 feet out.


I don't see how you can get the breakcord to do its job before the bridle would come into contact with the edge of the building.

That's why you want to make the S/L a bit longer than the distance from the railing.

See the pic.

I am in no position to suggest B.A.S.E. advice as I have no experience, but I thought I would share my $.02. Tell me if it is dumb or plausible. You can get one of those 10-15 foot retractable dog leashes. It seems you don't want a sudden jerk on the pins when the canopy is pulled out. Well you could jog off the edge with the leash cause it will always maintain tensionanywhere you walk within its range. Then the Break Cord can be attached to the end of it and around your bridle. It will help sustain the shock to your pins and help get better separation without hitting the cord on the edge of building. Check out the picture. Let me know what you think.

Dale

 
Hi Jap,

We had the exact same scenario last night on my first B also a 220 sl jump. i had ground crewed on a few B jumps prior i had seen the bridle extension used in the past and this functions well.

Last night on an underconstruction B, attachment point for sl was to five feet back from the edge, then the edge of the building was quite sharp, we basically larks headed some long climbing sling to the bridle end at the PC attachment point and then attached the sl to the anchor point on the b.

This allowed the pc to hang over the side. and removed the bridle issues you mentioned, if you can visualize what i mean?

d-bag it. That's my choice.

Dumb question, but I can't help it.

-How do you get the static line back if you're jumping by yourself?

It's probably a stupid question but I can't figure it out and of course I've never seen one of these things.

Make something like this: http://www.blincmagazine.com/...owthread.php?t=23747

Cheers!

Do a search on carry with you S/L

A-ha. Those nice construction people even left little eye hookie-things for you to tie your thingy onto. How polite of them, they must have known it would be jumped off of!

I can't get into the Blinc website, I'll hafta register later....

& I'll search that carry with deal too, I still can't picture in my mind how it could work.

Thanky all.

There's a nice step by step guide here.

Well, that picture's got me jonesin'

So after deploy the thing breaks...ok I get it. The cord must be strong enough to get your shtuff out but not strong enough to hang you. That makes sense. So you were looking at line between 40-160 lb test if that's what I read correctly (160 after doubling 80). -Has anyone ever had problems with a 40 lb test breaking early?

If freaking base jumpers would employ their ingenuity to other things we could rule the world.

...rule...the...world...<Acme scrambles for Pinky & the Brain reruns for ideas...>

-I don't base jump but the mechanics of it are fascinating.

Dude sorry to pick on you but i do so as of i like you(not love but as a person)

DONT play in the SL area before you figured out your brakes,infact please make your brakes before jumping off anything else than a safe S,Brake settings made to stall your canopy in opening will result in injury at some point,please get your settings set before playing in that area...

Please reconsidder using your toogles vs risers at low objects a riser turn will move you away from the object fast but it also eat alot of altitude compared to a toogle turn.
you can pop your brakes whith out getting a surge,also a thing you should learn before playing in the low area..

how high is the building below you? do you need a running exit? if so did you considder to freefall it?