What is the best response? This morning I found myself a bit head down on a 2 second delay. My natural response was to tuck legs a bit, but not good if the bridle was to catch on them! What would be better, to pull the head back & arch through the chest?
I'd say it depends on your altitude, and your experience with aerobatics.
I have seen expert aerialists recover from head down launches by tucking and completing a front flip. I don't recommend this technique unless you have extensive aerial experience and good front flips. This is one of the reasons that I'd highly recommend diving (and aerial) training for any BASE jumper--even those with no desire to perform aerobatic maneuvers.
Without aerial training, I'd probably pull my head up and try to arch out.
In either case, don't get so carried away trying to get flat and stable that you forget to pull. I am familiar with at least one fatality that resulted from an over-emphasis on trying to get stable (and consequent loss of ground awareness, with high speed impact prior to any attempt at deployment). In the end, pulling on time is more important than pulling stable.
--Tom Aiello
tbaiello@mac.com
The best thing is to exit head high and not go head down in the first place.However if you do go head low: pulling the head back and arching will not help you at this point.The best move is to bring the knees in a bit as soon as you feel that you are going head low.Unless you have exited very poorly your bridle should not be any where near your legs.If you are so head low that your bridle is caught on your leg then you have already blown it:1st by exiting poorly and 2nd by not recognizing it and trying to correct it.Anyway a little headlow is not a big deal when you have the time to recover from the bodies pendulum reaction:it just hurts;)
have fun
Trent
Were you thinking hand held, or stowed? Re-reading, I'm not sure.
--Tom Aiello
tbaiello@mac.com
Thanks for the prompt replies. I went stowed. It was never really a problem as I was only slightly head down. A front loop would have been a definite overkill in this particular case. It did however take me by surprise a bit as I have had a very fortunate track record on stable exits to date. Perhaps I am getting a little cheeky in wanting to look down on exit these days!
My question related more to the physics of stopping a low air speed head down getting worse. Also my desire to stop any bad reflex/habits such as leg tucks (if that is in fact a bad habit? i.e. no chance of back sliding on a 2 second delay)
Thanks again
Thanks for the advice. Spanking the pony sounds like an Australian BASE nationals event (points scored for number of times hands come in contact with the buttocks):+
>My question related more to the physics of stopping a low air
>speed head down getting worse. Also my desire to stop any bad
>reflex/habits such as leg tucks (if that is in fact a bad
>habit? i.e. no chance of back sliding on a 2 second delay)
I consider myself deeply experienced in head-down exits, so I'll share some of my thoughts.
I do not think that the "leg tuck" is a bad habit. It is perhaps the only thing that can stop a forward rotation or at least substantially nullify it. I've done them lots myself, mostly when taking running exits with a very hard launch from underhung objects (these super-hard exits, I think, tend to over-rotate in a systematic fashion). The leg tuck controls them, and I've never seen (nor heard of) a bridle entanglement resulting therefrom. Nonetheless, always good to be aware of the possibilty.
I'd think that there's more risk of bridle entanglement from wildly flapping arms, honestly. Clearing a bridle from around one's arm is not terribly hard, but a failure to do so would be a fatality.
Let me concur completely with two of Tom's points.
First, don't get so hung up on regaining stability that you impact before deployment. I've come close to doing this myself, once. It was frightening, and easy to fall into from a 440 foot object. Get something - ANYTHING - out before you go past the point of no return. I've seen dozens of deployment bounce off feet, done on backs, etc. and they are amazing in that they almost always work out more or less. In contrast, going in with nothing out will kill you with 100% certainty.
Second, dive training is so useful for both preventing problems like this and learning how to deal with them WHEN they happen, and they will eventually happen to everyone. You need not become an expert in the famed twistyflips and flippydoos, but learning how to do front rolls and rear rolls (as well as effective barrel rolls) sub-terminal - as well as learning when to deploy from each - will likely save your life if you jump enough. Besides, going to the pool with one's mates and making big splashes is always good for a night of fun.
And, hey, front loops are super fun :P
Peace,
D-d0g
ddog@wrinko.com
http://www/wrinko.com
>>My question related more to the physics of stopping a low
>air
>>speed head down getting worse. Also my desire to stop any
>bad
>>reflex/habits such as leg tucks (if that is in fact a bad
>>habit? i.e. no chance of back sliding on a 2 second delay)
>
>I consider myself deeply experienced in head-down exits, so
>I'll share some of my thoughts.
>
>I do not think that the "leg tuck" is a bad habit. It is
>perhaps the only thing that can stop a forward rotation or at
>least substantially nullify it. I've done them lots myself,
>mostly when taking running exits with a very hard launch from
>underhung objects (these super-hard exits, I think, tend to
>over-rotate in a systematic fashion). The leg tuck controls
>them, and I've never seen (nor heard of) a bridle entanglement
>resulting therefrom. Nonetheless, always good to be aware of
>the possibilty.
I know that it is not good MOJO to disagree, but I will anyway. I disagree with your statement about leg tucks D-Dog. From what I learned in physics class, and from watching olympic diving meets, a leg tuck will lower your rotational moment of inertia, meaning it will be easier for a person to rotate. Thus, in conclusion, leg tucks will increase a head down position, and may further increase it into an "on the back" scenario.
Stopping a head down rotation in sub terminal is all about the launch. The starting launch dictates body position greatly.
Maybe you could consult with some of your "aerobatic" BASE buddies. I do not know that much, but from what I have gathered, it is much harder to do a flip in the "lay-out" position. Tucking makes flips much easier. If flips are intended.
I do see value in the "leg tuck" theory in that it may reduce the chance of your bridle or canopy wrapping on your legs. See "speed hooks = death hooks" discussion. This illustrates why it is important to wear the right type of boots.
There are many things to kill a BASE jumper, and canopy entanglement is a big one. Tucking the legs may prevent canopy entanglement, but it will also INCREASE the rotational momentum.
So, as far as the physics go, in sub-terminal environment.....there is no real way to counter a rotation other than to carefully launch.
Focus on the launch, and the rest will go smoothly.
Sorry to say it, but your statement is flat-out wrong. You are ignoring the linear acceleration effect of the movement of the legs up and towards the head, which counters the rotational effect of the forward roll. Making oneself "small" in general will speed up rotation, but the act of pulling the legs up and forward does just the reverse, as anyone who has done so can verify. It's not an elegant solution to the problem, but it is a partial solution nonetheless.
I have dozens of exit videos showing this dynamic at work.
Additionally telling the poster that "stopping a head down rotation in sub terminal is all about the launch" is about as useful as telling someone asking for advice on correcting off headings that "it's all about not getting off-headings in the first place."
Peace,
D-d0g
ddog@wrinko.com
http://www.wrinko.com
ps: my "aerobatic BASE buddies" are all too busy doing flippydoos to worry about your incorrect posts :D
hi ddog,
first I have to apologize for my bad english. I´m from germany and I try do do my best.
in my opinion, tucking the legs is no good idea. of course it is a natural reflex for a skydiver at terminal to get back in a stable position, but in lowspeed it will get even worse (bridle-entanglement, and so on...). how about that: your rotate-axis is running from left to right through your hips. imagine you bend yourself over a fence and you can lie stable and flat in a correct balance, like you are in freefall. then you realize, that your emphasis is moving towards the head and you go "headdown". What will your reaction now be? Yes, you will not tuck your legs. you will straighten them out, you will not remain arched, you will put the arms back just to prevent yourself from flipping over.
It´s that, what I tell my students and I know that breaking with that reflexes is hard work, because it is opposite to what they have learned at skydive-school.
I passed this one onto my fioncee - she is an ex-gymnast (come on guys no wisecracks) due to age (what a sheit sport, done when you turn 18 basically)... She agrees with D-Dog completely, and I can attest that an olympic level gymnast knows quite abit about body control in sub-terminal applications. Show me an average joe that is spatially aware doing a triple double.
>>Show me an average joe that is spatially aware doing a triple double
Show me a BASE jumper that can do a triple double on a 2 second delay.
What's the point? Well, nothing really. After all, it is up to each individual to make their own choices. Because, if an accident occurs, I personally will just blame the jumper.
Seriously, it's a simple phenomenom known as "Operator Error".
It's like a low hook turn under a highly loaded elliptical.
It's like Mama Cass eating a ham sandwich.
It's like John Denver flying an airplane.
It's like Bill Clinton not making Monica swallow.
??? I think there is quite a bit of plausibility in my statement if you want to learn how to save your ass in an over/under rotational incident. I was being a bit sarcastic in my last sentance - but at the same time, my point is this - I'll bet my money on someone that knows how to spot themselves in a triple double type crazy arse rotation over someone who has just started doing arials through the sport of BASE without any kind of diving instruction or gymnastic instruction. The feats a gymnast can pull off are pretty amazing if you took the time to look at it, not to mention they learn it by the age of 12.
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