Mini-Risers - What's the problem?

[goose491 0]

Hey all,
The "My first Base Rig" article was pretty cool and informative. I noted at one point however, the author mentions that he recommends that no BASE jumper ever use mini-risers. This is because they have failed skydivers in the past. I did a quick search but could find nothing... In what ways are mini-risers more vulnerable to malfunction than standard?

Nick

My Karma ran over my Dogma!!!

[darkvapor 0]

What I would like to know is: In the documented cases of mini-riser failures, have they been sudden failures or due to lack of maintenance and timely replacement? If I remember correctly, I think the general recommendation for replacing minirisers (other than obvious wear and tear) would be around the same time a canopy needs relining. Would regular replacements have prevented mini-riser failure? Or is it an inherent weakness in the design?

[wlie 0]

I've got the regular wide kind of risers. What is that? Type 8 is that correct?

Any general rules about when it should be replaced?

Only asking because I'm thinking of replacing them with the mini ones so I can pull the slider down and leave it behind my head.

My other ride is the relative wind.

[AggieDave 6]

Before you do that, read the stuff that Bill Booth posted a while back in this forum about the mechanical disadvantage of mini-risers. You might think twice about jumping them.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[goose491 0]

I'm useless at doing those searches!!

I type in "mini-risers, disadvantages" and I get your post!

My Karma ran over my Dogma!!!

[darkvapor 0]

Well, from what I know, the biggest disadvantage of mini-risers is that they are weaker and wear faster. Meaning you have to be more diligent in replacing them and making sure they are in excellent condition. However, they look better and have lower drag.

I'm not sure what mechanical disadvantage AggieDave is talking about. There is a mechanical disadvantage in using mini-rings over regular rings. But no *mechanical* disadvantage of mini-risers. Just their slightly higher failure rate. That's what brought me to ask my earlier question about what causes catastrophic riser failure.

[TomAiello 25]

Quote

...the author mentions that he recommends that no BASE jumper ever use mini-risers. This is because they have failed skydivers in the past.

The cases I've heard about have to do with catastrophic failure (i.e. a riser breaks) of a well-used (so some wear) skydiving type 17 riser. Typically, they were attributed to worn risers combined with a hard opening. Obviously, this is a cut-away situation. Since you can't cut-away in BASE, it becomes a life flight (or worse) situation.

I've never seen a case where the failure of a riser resulted in injury on a skydive--just a reserve ride. So it may be that you are having trouble locating reports because few people bother to report non-injury incidents.

I know it's a bit off topic for your post, but I figured I'd try to clarify that my advice is really only good for the BASE environment. My skydiving experience is limited enough that asking me for skydiving advice is a relatively silly idea.

-- Tom Aiello

[email protected]
SnakeRiverBASE.com

[AggieDave 6]

Quote

There is a mechanical disadvantage in using mini-rings over regular rings. But no *mechanical* disadvantage of mini-risers

That's what I was trying to say, sorry, through my nifty medicated haze (i'm sick) I didn't get the words out there quite right.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[goose491 0]

Quote

I know it's a bit off topic for your post, but I figured I'd try to clarify that my advice is really only good for the BASE environment. My skydiving experience is limited enough that asking me for skydiving advice is a relatively silly idea.

Not at all! What I'm asking about is the risers themselves... BASE jumpers say "No way!!!" to mini-risers so you'd be a perfect person to ask why. I have mini-risers/ mini-3ring system. So, the only 'problem' with mini-risers is that they wear faster?

A few more questions to all: When would you replace mini-risers vs. regular ones? I bought my rig second hand and the container had but 100 jumps on it. I fugured I'd replace the risers when I brought that number up to 500 (or earlier if I noticed something which required it) Sound good?

And what's the mechanical disadvantage of mini-3-ring?

My Karma ran over my Dogma!!!

[darkvapor 0]

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=search_results&search_forum=all&search_type=AND&search_string=mechanical+advantage+mini+rings

Go through those past threads to read about the mechanical advantages of the rings. I believe its something like: Larger rings have a 200:1 mechanical advantage while mini rings is something like 30:1. Big difference, however, its not so bad that people don't recommend or use mini-rings. I'm sure there have been incidents of hard cutaways as a result of using mini-rings, but most people say they were able to cutaway just fine.

For the risers, I think 500 jumps might be a tad much. Maybe closer to 300 (just to be on the safe side), but it all depends on how much you use/abuse your gear. Maybe call the manufacturer for a better estimate.

[goose491 0]

Thanks,

I assumed it had been brought up before but as I mentioned earlier, I am useless with the search option. I don't really get the significance of the numbers 200:1 and 30:1 mechanical advantage... Are they talking strickly about the ease of pull (during cutaway)??

My Karma ran over my Dogma!!!

[PhreeZone 15]

All your weight on one riser while spinning can create 2-3 G's worth of force to the amount needed to breakaway. 200 pounds at 3 G's on large rings is only about 3-5 pounds force needed to achieve breakaway. On minirings that would be about 10-15 pounds force. At about 30 pounds of force the teflon cable can get sucked through the grommet in the riser.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[billvon 2,426]

>Larger rings have a 200:1 mechanical advantage while mini rings is
> something like 30:1.

While it's true that there is a difference in mechanical advantage, that is generally not an issue in BASE jumping where mains are not cut away while airborne.

[billvon 2,426]

>In what ways are mini-risers more vulnerable to malfunction than standard?

Initially, non-reinforced type-17 risers were breaking near the 3-ring assembly or at the grommet during hard openings. This has largely been fixed with the introduction of reinforcement tape (check out your risers for the blue or red material in the center of the riser stackup.) Since there's no good reason to use mini-risers on BASE jumps, people didn't go back to them after the problem.

[goose491 0]

Thanks Phree!

That's what I figured. I'm not all that worried that I jump mini-rings then.

Bill,
Thanks for your input too. I'm not worried about the mini-risers either now

My Karma ran over my Dogma!!!

[PhreeZone 15]

The reason minis are bad are if you are heavy or have a high G spin the forces can add up quick. Break away might be impossible on minis at above a 4g spin.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[AndyMan 7]

Quote

The reason minis are bad are if you are heavy or have a high G spin the forces can add up quick. Break away might be impossible on minis at above a 4g spin.

Can you point to any fatality or near miss where this played a role?

Yes, I understand the physics of it. No, I don't think it's a very common problem, even among slightly heavier guys like me. I'd much rather see people installing hard cuttaway housings into their risers then be swapping small for large.

_Am

__

You put the fun in "funnel" - craichead.

[faulknerwn 37]

The most interesting one I ever saw was a "heavier" jumper who actually bent the small ring during a hard openings. The opening broke lines as well and there was an uneventful cutaway, but I was amazed at the force it must have taken to bend a ring into an oval shape like that.
W

[billvon 2,426]

>Can you point to any fatality or near miss where this played a role?

About four years ago, someone was very seriously injured when they could not release their mini-risers during a spinner. The risers were also 'integrity' type which added to the problem.

[goose491 0]

Quote

The most interesting one I ever saw was a "heavier" jumper who actually bent the small ring during a hard openings. The opening broke lines as well and there was an uneventful cutaway, but I was amazed at the force it must have taken to bend a ring into an oval shape like that.
W

Woa! "heavier" jumpers should definately not deploy in head down position!!!

Seriously though, that guy must have been hummin when he dumped.

My Karma ran over my Dogma!!!

[faulknerwn 37]

Girl actually. And while there was no video so I don't know her exact body position, she had been doing belly-flying that jump - no head down or anything.

W

[wmw999 2,146]

Quote

Woa! "heavier" jumpers should definately not deploy in head down position!!!

Disagree. Heavier jumpers should jump gear that allows them to deploy in any position. Remember the priorities:

Pull
Pull at a safe altitude
Pull stable

If you're jumping gear that won't really allow you to do #1 or #2 without worrying about #3, then it might be time to reconsider your gear choice. Especially if you're not experienced.

Wendy W.

There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

[AggieDave 6]

Quote

Heavier jumpers should jump gear that allows them to deploy in any position. Remember the priorities:

Thats impossible with the gear on the market today. I easily hit 180mph doing head down. I accidently hit 224mph doing a head down a few weeks ago. If I deployed doing 224mph, 1 my canopy would most likely explode and 2 there's a good chance I wouldn't be better off then the canopy.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[billvon 2,426]

>If you're jumping gear that won't really allow you to do #1 or #2
> without worrying about #3, then it might be time to reconsider your
> gear choice.

Or you might want to reconsider intentionally exceeding the speed limits of your gear.

[livendive 8]

Quote

I've never seen a case where the failure of a riser resulted in injury on a skydive--just a reserve ride.

There was a tandem fatality due to one a few years ago. However it wasn't a mini-riser, and would have been just a reserve ride had it been the other (non RSL) riser that broke. Since then we've added a lanyard that should prevent such an accident in the future.

Blues,
Dave

"I AM A PROFESSIONAL EXTREME ATHLETE!"
(drink Mountain Dew)