The following things can contribute to tailgate hangups:
1) Using the wrong rubber band. The correct rubber band is the "small band cut in half" or, actually, a 1 1/4" x 3/16" rubber band. This size can be ordered from the manufacturer directly, so there is no need to sit around with scissors cutting up a bunch of rubber bands to make them the right width.
2) Tying the rubber band to the tailgate and placing the wraps inboard of the knot. When the wraps slide across the knot, they can hang up, causing the tailgate to stay closed.
3) Placing the tailgate too low on the C line. The tailgate should be placed as high as possible on the C line without catching tail fabric. Ideal placement is right at the very top of the control lines.
The following can contribute to tailgate failure (i.e. the opening does not have the tailgate constraint, and occurs in a tail first fashion).
1) Worn out rubber bands. If you tie the rubber band onto the tailgate, you will eventually wear it out and it will break. If you are lucky, it will break during it's last opening. If you are unlucky, it will break during the climb, the hike, or while being thrown into the trunk of the car to drive to the object. If that happens you will get to have an untailgated (tail first inflation) opening.
For this reason, I do not recommend tying the rubber band to the tailgate--I prefer to use a new rubber band for every jump, minimizing the chance that a worn rubber band will fail prematurely and give an untailgated opening.
Of the four methods you have shown, I would choose the first. Given a wider selection, I might wrap the rubber band another time (three "laps" as you say).
If you are worried that you will run out of rubber bands, feel free to send me a PM and I will mail you a bunch of them.
If you are even more worried, call up the manufacturer and order yourself a couple pounds of rubber bands cut to the proper width (3/16") for BASE. They are not listed on their standard catalog, but the price is the same as the skydiving width (3/8") listed here. I order about 20 pounds of rubber bands at a time, but most jumpers probably won't need a supply that large.
(This post was edited by TomAiello on Dec 24, 2011, 10:24 PM)
Dec 25, 2011, 7:56 AM
Post #6 of 47
Re: [SubTerminallyill] Help with tailgate
[In reply to]
what are the dangers of using a 3/8" opposed to the 3/16"
3/16" has a lower breaking strength. In the event that the tailgate rubber band somehow becomes entangled, it will take more force for the 3/8" band to break, and therefore make a hangup more likely.
When we select a rubber band for a parachuting purpose, we aren't just selecting a minimum strength--we are also selecting a maximum strength. Parachute deployments are very complex systems, and they can fail in very unforeseen ways because of the amount of chaos involved when we--basically--take a tent and toss it out a car window, expecting it to set itself up properly. One of the reasons we use rubber bands is that they will act as a fail safe in the event that some part of the system malfunctions (in this case, if the rubber band somehow hangs up on the tailgate). Using a stronger rubber band (like the black ones that hopefully no one is using anymore) can lead to a hangup simply because they are too strong. The same reasoning (although to a lesser extent, as they are weaker than the black ones) applies to the 3/8" bands.
Also, the stronger and more durable a rubber band you use, the more likely you are to be tempted to leave it on for "just one more jump." That makes it more likely to have it fail prematurely (in the pack tray before deployment), leaving you with an untailgated deployment.
(This post was edited by TomAiello on Dec 25, 2011, 7:58 AM)
Dec 25, 2011, 11:14 AM
Post #11 of 47
Re: [TomAiello] Caution: the following post is counter productive.
[In reply to]
I once had a friend rig a static line with a used condom. I wonder if there's a way to work one of those into a tailgate system?
Ew. Hope it was his.
Just to change the subject since it was drifting anyway...I once heard a "DZ rigger" say he reduced pin friction by lubing the closing loops with KY jelly (this really happened back when I was looking into switching from dacron to spectra).
Dec 27, 2011, 7:16 AM
Post #17 of 47
Re: [Fledgling] Caution: the following post is counter productive.
[In reply to]
I've also used a woman's hair tie, masking tape, and several strands of elastic from my sock. :)
I you're using masking tape you're best off to remove the tailgate and put the tape directly around the bundle of lines.
And ensure that it is positioned in the same location and stays that way. If it slides down the brake lines then the force they exert on the tape gate decreases, possibly to the point of a hang up.
You should also make sure the tape is clean, dry and unwrinkled. Dirt, moisture and wrinkling can change the breaking strength quite dramatically. It's easy to see this for yourself by just playing around with some tape at home for a few minutes.
I always thought that black rubber bands were universally frowned upon due to their higher breaking strain.
"Universally" is a tricky concept.
I think that most jumpers, including manufacturers who used to recommend the black rubber bands, have now decided that they are a bad idea.
There will always be jumpers who, out of habit, laziness, or just stubbornness, refuse to adopt standard safety techniques. I've also met jumpers who use older technology as a sort of badge of manhood, because it makes them more "hard core" to do things in a manner that is less safe.
There are also some jumpers making less than mainstream gear and rigging choices as the result of thoughtful, reasoned decision making. They've just made a different assessment than the majority.
Dec 27, 2011, 6:32 PM
Post #22 of 47
Re: [GreenMachine] Fledgling --We've found common ground
[In reply to]
Actually it is just plain correct Straight out the box the black rubber bands have a significantly higher breaking strain than keener type rubber bands of the same size. Not sure if they actually ever caused a tailgate hang up but several documented cases of bridle hang ups on Prisms equipped with a multi that was stowed using black bands exist. I believe it was those bridle hang ups that led to the conclusion that black bands were no good for use with tail gates. I'm sure Tom A could add more specific info as it was a bit before my time.
Dec 27, 2011, 6:43 PM
Post #23 of 47
Re: [Fledgling] Fledgling --We've found common ground
[In reply to]
Not sure if they actually ever caused a tailgate hang up...
There was an extremely well documented case of tailgate hang up on a black rubber band in Canada, about 10 years ago. The jumper impacted with the canopy still bow tied in the tailgate, but fortunately it was a jump in Canada, during the winter, so the snowbank he hit more or less saved him from injury.
They shot a bunch of video in the landing area when they tried to clear the tailgate, and posted it all up on-line.