Bridel lenght on SL jumps

[Faber]

Heya guys
I like SL jumps,but i hate the long bridel that i can wrap my self into etc etc

therefore i were thinking of making a SL bridel(ie a bridel only meant to be used on SL jumps).

Im jumping the carry on SL and can see the advatagens to get 2 more loops besides the pc loop on the bridel and then im thinking of shorten the bridel down to 4ft.

Its the lenght of the bridel i want oppinions on.

My theory is that a 4 ft bridel ofcourse will open your canopy 5 ft higher(not that it means that much as im no lower than 140ft at this point).
Also the bridel will be in more control.

The pc will still have the pc on ofcoyrse and in case of a premature break were the PC should save my life to a hospital ride to get a bone fix,my idea is that you´ll have no buble as your that close to 0ms as your falling so the pc should catch air anyway.

This discuss has been on ultra low freefalls before,but i want comments on this in a SL weiv.

I did a search in tecnical and found this from back in 99 which i might thing is out of date.

Any oppinions is appritiated.

Cheers
Faber

[Johnny Utah]

Im jumping the carry on SL and can see the advatagens to get 2 more loops besides the pc loop on the bridel and then im thinking of shorten the bridel down to 4ft.

Its the lenght of the bridel i want oppinions on.

My theory is that a 4 ft bridel ofcourse will open your canopy 5 ft higher(not that it means that much as im no lower than 140ft at this point).
Also the bridel will be in more control.

The pc will still have the pc on ofcoyrse and in case of a premature break were the PC should save my life to a hospital ride to get a bone fix,my idea is that you´ll have no buble as your that close to 0ms as your falling so the pc should catch air anyway.

If I understand you correctly, you want to shorten the bridle so doesnt get in your way. As you probably know, a 4-foot bridle has a good chance of putting the PC in a burble. Youre saying that there will be no burble at first if the breakcord breaks prematurely. I think most people underestimate how soon a burble starts to occur. Granted, it will start out small and maybe insignificant, but it will rapidly grow into a sizable burble that can cause your PC problems.

So what you should ask yourself Faber is, in the case that the breakcord breaks prematurely, are you willing to gamble that the PC will inflate well and immediately, and that there will be enough snatch force to get your parachute coming out before a significant burble occurs?

I would come up with a different way to control your bridle. Rubber bands are sometimes used to control the bridle. There are a lot of various ways to do that sort of thing. Some ways may be Black Death so be careful how you rig it (such as dont use a big rubber band that could slip over the PC, etc.). Also if the rubber band doesnt release the bridle easy enough, then you are essentially stuck with a short bridle. Chances are the bridle will come loose before a breakcord breaks prematurely, but keep things like that in mind.

If you do decide to experiment with a shorter bridle for S/L jumps, Keep in mind the shorter you make it, the more chance it will have of putting the PC in any burble that will exist at anytime during that freefall. Also keep in mind that PCs dont always inflate right away. Also, there will be less snatch force involved should the PC be mingling with a burble. You may want to use a bridle extension so that you will have two breakcords to break (one after the other). Apex (formerly BR) sells them. That way you have a second breakcord that must break too before you are let go. Also keep in mind the bridle extension wont help if your carry-on S/L is cut by the anchor point.

Hope this helps.

[BASE_689]

> ...I think most people underestimate how soon a burble starts to occur. Granted, it will start out small and maybe insignificant, but it will rapidly grow into a sizable burble that can cause your PC problems....
I agree with EVERY point made by Johnny.
Yes, at the very first beginning, the airflow is so slow that there is no burble. But there is also NO PULL (by PC on bridle) because of such a slow airflow. It's just when there is a little bit of airflow that would cause the PC to start pulling decently that Mr. Burble shows up.... .and s h i t can hit the fan (and it WILL do )
What do I do to prevent excess of bridle to "stay among the balls" during exit?
I use a very thin elastic band (square section, 1 mm of thickness) with a number of wraps that just barely keeps the S-folded bridle there, it just hold the weight of S-folded bridle (the same very thin elastic bands I use for keeping in place the S-folds of my Multi into my Prism, see old thread).
So, during exit, the S-folded bridle is off the way, and in case IT IS NEEDED, the above very thin elastic band gets loose the S-folded breidle very easily and very fast (otherwise, why would you keep the PC as a backup, if the S-folded bridle is VERY CONSTRAINED by "skydiving rubber bands"?!?!?!?!?!? ).
Just my 0.02€

[Faber]

Thanks for the fast replys guys.

I know people has testet 4-5 ft bridel to use at ultrlow freefalls before whith out problems(as i know off).

I DO use a back up cord as i do my SL,so the chance of getting a "blown" breakcord were i need to rely on my PC aint that big i figure(unless the "cut away cord" is the weak link).
Also as im doing SL´s i usaly dont do them in 0 winds but in either x or straingt in the back. even 2ms usaly blow the most of my pc up as im out there. I do belive that it will get air before i get the burble..

Its not for no reasson im posting this,im hoping people has goone theese ways before and found answers i dont need to find myself.Therefore i need as much input i can get on the subject before i do my finaly dessision to try it out.

I also wrap up my SL and holds it by a rubberband,secured the way you hold a bridel if you want to PCA sombody off,the rubberband is lost at that jump as as the bridel extract the rubberband simply fall off.

Ill be interested in seeing if people do other stuff by their bridel

[Gaddster]

The points made by the previous posters referencing the effect bridal length has on how burble affects your pilot chute are valid and should be factored in when considering a shorter bridal for SL jumps. However I think there is perhaps a more important point to be considered when it comes to the effect a shorter bridal has on your static line deployment. When static lining, the PC only really serves as a back up in case of premature static line failure. The best thing is probably to do everything you can to minimize the potential for premature breakage in the first place. The fact is, shortening your bridal significantly reduces amount of dynamic force placed on your breaking element and therefore reduces the chance of premature breakage. In order to understand this you must think in terms of dynamic force vs. static force. Let’s use the industry standard of 1/4in cotton webbing rated at 80lbs as break cord. Yes, you could use it to lift something off the floor weighing at or nearly 80lbs, this is a static load. However it takes much less weight under dynamic conditions to break it.

Todd at Apex repeatedly tested this principle with the same results, and suggests doing a similar experiment yourself at home. He hung a standard 9ft bridal from the ceiling by 80lb break cord and at the other end tied only a five pound shot bag. When dropped from nine feet, the five pound weight broke the 80 pound break cord every single time. When you consider this, it becomes apparent that the dynamic force generated solely from the weight of your canopy and lines reaching the end of your nine foot bridal has the potential break your SL right then and there.

Acceleration due to gravity and the potential energy generated within a falling body increase logarithmically. So if you shortened your nine foot bridal by say three feet it wouldn't just reduce the dynamic force by 1/3, it would be a significantly greater reduction. To me this chance to decrease the likelihood of premature static line failure in the first place is worth shortening the bridal if the jump is low enough where this premature breakage would result in too low of an opening. Keep in mind none of this takes into account the pontential for anchor/pre-cord failure.

I'm still a fan of the bridal extension mentioned in an above post. Why would you not want a back up? As long as they are sequential and don't have to load and break at the same time. Something else you could do in place of actually having a shorter bridal is to tie a loop (it is important that this loop will not slip or com out) several feet down the bridal from the pilot chute attachment loop to achieve the same reduction in dynamic load. You cold tie two loops six inches apart if you wanted two break cords as with the Apex bridal extension. You could even construct a bridal with extra loops made in this way. Maybe the best thing to do would be to have the extra loops as described above and leave the rest of the bridal and the PC hanging down below the tie off point(s). Then you'd could have the benefit of the shorter bridal length to the static line, but the length of the bridal to the PC would essentially be the same keeping the PC more out of your burble should you need it.

I'm not telling anyone how to BASE jump. I'm not qualified for that. I have thought a lot about this though and talked to others about it before at length and done my own experiments. So while it makes sense to me it is still just meant as food for thought. I think it's to stuff to consider when deciding for yourself how you want to do your low static lines.



Take Care,

Gaddy

"Only those who risk going too far, can ever find out how far one can go." -T.S. Elliot

[Faber]

Hi Gaddy
Im walking whith the same thourghts as you have here,i however didnt know about the force of breaking the cord will be more if i have a shorter bridel,im gonna do some of thouse tests.

If you have video of jumps whith a shorter bridel can i see them? my mail takes 10mb as max base850ATgalnetDOTdk

its really interesting this...

Thanks guys