Static line launch technique

[Gus937]

I have an object in mind that I've lasered at 132 ft, which is a good 20 or 30 ft lower than I've jumped before.

Is it in Continuum 2 where you see Jimmy P doing a practice s/l jump in to the superbowl? Anyway, he doesn't do a 'normal' BASE launch he just drops straight down, perfectly head up, almost vertical. Am I right in thinking this technique is supposed to get you flying quicker by minimising the amount of swinging around your body does on opening?
Does anyone have any opinions on whether this works? Or how much of a difference it makes? Or whether it (being vertical rather than horizontal as the canopy is extracted) may affect heading performance?

Thanks,

Gus

[JaapSuter]

I think that in general that the shorter the delay the more head-high you want to be. Completely vertical and standing up is not good either, but for a static-line jump it definitely won't hurt to be at about 50 degrees instead of belly down. Like you say, you will swing less under canopy. That way you will be in stable full flight sooner, giving you more time to fly your canopy properly.

I've experimented with different body positions jumping a 180ft span and I could definitely notice the pendulum effect depending on my body position. These days, when I jump that span, I just kinda step forward and then fall back, instead of launching out. It's very head high.

This opinion is based on about sixteen PCA and static-line jumps from various low objects. Not very statistical, but something I'm pretty comfortable with.

[JaapSuter]

To add, as long as you are not too head-high, e.g. over 70 degrees, I don't think it will affect your heading performance too much. Most containers open very clean at the top (compared to the bottom of non-dynamic corner containers, which has stiffened corners).

[BASE_689]

> ...he doesn't do a 'normal' BASE launch he just drops straight down, perfectly head up, almost vertical. Am I right in thinking this technique is supposed to get you flying quicker by minimising the amount of swinging around your body does on opening?
Yes, indeed, from 132' - 40 m ish heights you MUST exit stand up to avoid swinging once under open parachute.
Furthermore, also your forward push must be minimal, only "enough" energy in launching just to get you clear exit itself but your forward speed MUST be minimal, so, once again, when (and immediately after) you are under open parachute there NO SWING going on.
Then, from such heights, what you do next, it's up to you:
1) unlock brakes going to deep brakes, slowly releasing toggles up and when it's time to flare (it's coming jolly soon ) you flare from where you are (=from the toggles position you have got in that moment)
2) on due time you flare on risers
3) you do one of the above points but you ALSO do a very good indeed PLF (Parachute Landing Fall)

> Does anyone have any opinions on whether this works?
Yes, my friend, it works!!!! Jolly good indeed!!!!! Just be careful, being so close to object and giving yourself a minimal forward push, that you and your equipment/your backup PC can safely clear ANY part of the structure. So, head up on how exit point (...and parts below... ...sticks/bits/whatever protruding) are made of

> Or how much of a difference it makes?
We don't know!!!!! We NEVER tried to do a normal strong forward push with 45° body in very low BASE jumps!!!! So we cannot tell the difference!!! We stick to what it works!!!! And to what (we think it) is safe!!!

> Or whether it (being vertical rather than horizontal as the canopy is extracted) may affect heading performance?
No, I would say that what is VERY important for heading is eveness of shoulders, not the fact that you are 45°, flat or standup; also a factor for heading performance in SL jumps is (absence of) cross wind: remember that the airspeeds that affect parachute on opening in SL BASE jumps are very low (vertical) airflows, so also a modest (what would be MODEST in a normal freefall BASE jump) cross wind can affect greatly your heading on opening.
Just my 0.02€

P.S.: I am talking about using ONLY vented and valved parachutes for those (low) heights

[BASE_689]

> Completely vertical and standing up is not good either
Why do you say so?!?!?!?!?
We do not have the instruments to evaluate EXACTLY the body angle but I would say that when we jump from such low heights (132' - 40 m and lower) our body position is 80÷85° (just guess...) but definitely a position that approaches way more the VERTICAL rather than the 45° position.

> I've experimented with different body positions jumping a 180ft span and I could definitely notice the pendulum effect depending on my body position.
We experimented from 105' - 32 m (it was a DB jump but this doesn't change the exit position/launch) and all I can say is that we are very happy of our standup position and very minimal forward push of our exits!!!

[Gus937]

Sweet, thanks Andrea.

The structure is very clean so minimal object seperation and snag factor shouldn't be a problem. If I get video I might post it. Depends on how graceful the landing is

P.S.: I am talking about using ONLY vented and valved parachutes for those (low) heights

For sure. I have an MDV Troll.

Gus

[BASE_689]

> Sweet, thanks Andrea.
Our master for low BASE jump parameters has been (years ago...) Crwper, the Canadian wonder of low jumps.
Among other things (that at the time I simply noted but I was/we were jolly far from applying immediately what noted ) he drew two big milestones, that are (giving for granted that the air space is all clear and landing is easy and unobstructed):
· 50 m SL BASE jump: you can do your exit (more or less...) as you like (45° and/or strong forward push), you have enough height to "absorb" oscillations due to swinging under parachute
· 40 m SL BASE jump: do a stand up and minimal forward push exit, otherwise you would find yourself that after the recovery from first swing you are happily sinking into ground with your body/harness/parachute/whatever

Any other height comprised between 40 m and 50 m is up to you, but my advice is that as soon as you start going (even slightly) below 50 m, your exit must approach as closely as possible the exit you would do from 40 m.
All the rest is experience in handling low BASE jumps and good old common sense

[#726]

Under 36 meters (120ft) its not great performances if you use the toggles, its better use only lightly risers for control your canopy, its important for not have a great speed in landing....ready for PLF
#726

[sabre210]

[QUOTE=JaapSuter] Completely vertical and standing up is not good either [QUOTE]

Reasons?????


Andrea how low before you'd say Vents and Valves would be necessary, and would you say that they matter more on sub200ft freefall than on sub150ft PCA's or static lines. I've done a 150ft A using my ACE and found it pretty civilised. I was thinking another 10ft off, or would experience dictate that would be a bad idea.

ian

[JaapSuter]

[QUOTE=JaapSuter] Completely vertical and standing up is not good either [QUOTE]

Okay, let me rephrase; go as vertical as possible while still exposing your packtray to clean air above you.

[BASE_689]

> would you say that they matter more on sub200ft freefall than on sub150ft PCA's or static lines. I've done a 150ft A using my ACE and found it pretty civilised.
Well, my personal feeling is that off 150' - 46m is around the lowest limit for safe jump WITHOUT vents. EVERYTHING must be perfect. No wind. As soon as you have a slight tail wind and your paracahute is going to start flying later (=lower).
Ask #726 how he flew with his standard Fox off our 150' - 46m new A, he just advanced few meters and had to do a very good indeed PLF (together with an attempt of flare on risers). Myself and #854 with vented parachutes had decent flights and flare on toggles and very good stand up landing.
If TODAY they do exist vented parachutes, why not to take advantage of them?!?!?!?
Yes, he did 102' - 31m (in DB) in an indoor and very religious BASE jump in your country around 15 years ago with a decent landing on risers with a NON-BASE parachute (forget vents...), but I don't see why we should shave off the technical improvements available nowadays and why we should do hardcore stuff (the 102'-31m without a vented BASE parachute perhaps was more a stunt than a BASE jump...) WITHOUT using the latest improvement in technology...
In the end, it's our poor body that is under parachute and is taken down to the landing more or less gently

[sabre210]

I hear what you're saying and tend to agree, which is why i haven't ventured below 150ft with my ACE despite serious provocation. I was just curious to know where people are generally drawing that line in the sand with regards low jumps on non-vented/valved canopies. Like i said i think i've found a height which still has a margin for funkiness. I also have to factor in to the equation the fact that i'm a heavier jumper (215lbs) with a large heavy canopy (310).

ANyway. Cheers

ian