High-G Auto Cutaway Mechanism

[rsibbald 0]

I am looking for a method of automatically cutting away in the case of continuous high-G loading.

e.g. imagine a small canopy spinning up on you so hard that you go unconscious within a second or two.

Does anyone know of any systems that can perform this? It can either be mechanical or electrical based, but it *has* to be reliable.

Please add random thoughts and ideas, as I may end up developing my own system to cope with this eventuality.

N.B. The canopy situation was an example, it is not the application I want to use this for. I would like to encourage innovative thinking and creativity - please don't let this degenerate into a "whuffo you want to do that?" thread!

[rsibbald 0]

Possibly the simplest method I am currently thinking of, is some way of securing a spring loaded device so that if your hand let go of a trigger (due to you either falling unconscious or losing control), it would spring away from your body and start a cutaway sequence.

[mr2mk1g 10]

Twin cutter tandem cypres with the white loop of the risers passing through the cutter.

Disadvantages:
you better hope you're going more than 78mph if you want it to fire.
won't stop g-loc from killing you above 1900ft.

Or just hook cypres cutters (or similar) on the white loops again, up to a dead man's handle - maybe a bite switch or something? Then have permanent way of completing the circuit (eg inline flick switch) before cutting away the experimental canopy (assuming that's what you're thinking of here).

[rsibbald 0]

I would not be able to use a Cypres activation control box as the trigger, just g-force or lack of user input.

I like the idea of having a 'push-and-hold-to-stay-attached-throughout' switch, (I would have my left hand free for this throughout the stunt).

Do Cypres cutters activate upon supplying the right voltage/current, or do they need a coded signal to prevent e.g. static charge activations.

Does anyone else have any mechanical based ideas? (Redundancy is always good!)

[mr2mk1g 10]

Problem with a system based on g forces will be it has to withstand the g forces inherent in opening shock. So you'll either need a computerised system which has an algorithm in it which only cuts away if it detects X lb of force for Y seconds or a far more simple system whereby the operator holds a dead man's handle during deployment before switching to a pure g force system.

[rsibbald 0]

Sorry, I should have been more specific in the original post..... The canopy thing was just an example.....

Think along the lines of a skysurf board....... except you definitely want to cut it away before you deploy anyway.

I'm starting to think that a manual release switch is much safer than electronics that can possibly go wrong.

It would be very useful to figure out a safe way of making the switch a reusable device though. Which it would need to be in order to repeat this type of jump without costing 2 cypres cutters everytime!

[mr2mk1g 10]

Is this a backup saftey system or just the way in which you want to do it every jump?

[rsibbald 0]

Just to be awkward: Both!

The cutaway will always need to be manually activated before any deployment sequence is initiated.
(Preferably less than £10 disposable equipment per jump)

The cutaway will also need to be activated instantly upon user loss of consciousness, probably due to loss of control resulting in 'high-G' maneouvres.
(Doesn't matter if this costs £1000 a shot)

Both mechanisms may, or may not be, the same.

[JohnGraham 0]

I had a thought about this a while ago when I was REEEEEEEALY bored in a certain bar and not getting pissed (yes, that actually happened once in a while!)
If you could design a combined cutter/pressure guage in the shape of a grommet (ie. donut shaped) you could fit it between the gromet of the riser and the gromet at the end of the metal housing (on a non-reversed riser), making the white loop short enough to keep them together.
Since the pressure applied to the white loop would tell you exactly how much pressure was being loaded on the riser, you could connect it all up to some computer and tell it to cut the loop if some condition about G-force was met. (i.e. if the jumper experiences more than 5G's for X seconds, or 7G's for Y seconds, etc.) but you'd have to get the unit to turn itself off below a certain height.

(You could "calibrate" the unit for each jumper - they'd basically just need to hang themselves up in a suspended harness by the risers, and the unit would know that that's how much force the user exerts on a riser when pulling 1G)

I have some stuff written down (Yeah, I'm a geek!) that you're welcome to have a look at if this is the sort of thing you're after.

[rsibbald 0]

Hey John,

Sounds like a funky idea - although that'd take more resources than I have avaialble to design and implement I think! I'd be interested to see what you have next time I'm up north. I might need you to crunch some numbers for me as well, regarding forces at different airspeeds....

[achowe 0]

you took the words right out of my mouth John.

-------------------------------------------------
Woooaaaaaa!!! Woooaaaa!!! I'm gettin' off it!

[mr2mk1g 10]

Go real chuffing simple.
Stick a big lead ball/weight half way along a steel cable.
First half of cable leads up fixed hard housing to leg and cutaway pad (assuming sky surf board).
Second half of cable leads down fixed hard housing to three ring circus where a pin is swadged on the end.
Pin takes place of Teflon cable in three ring circus.
Where the lead ball is there is no hard housing.
There must be room between the lead ball and the upper hard housing to allow pin to be pulled from circus by pulling on the cutaway pad.

During high speed spin centripetal force (ok I know we physics-whuffos never get the right force) works on lead weight/ball. Lead moves away from hard housings (which are fixed along most of length but not last inch or two to allow for articulation).
Thus force on weight pulls on both ends of the steel cable.
Cable at top is attached to cutaway pad which cannot move through hard housing.
Cable at bottom is therefore the only point of movement and thus pin is pulled.

Three ring circus works its magic and board (in case of skysurfer) released.
Ball can’t fly off and hit a house as cable is still within hard housing. You could even prevent the cable from doing anything but bowing out where there is no hard housing by ensuring the pin has a greater diameter than the internal diameter of the hard housing.

This would require a lot of thought about forces to make sure weight was sufficient to activate circus at a low enough spin but light enough to survive ordinary usage. I would also worry about cleaning inside the system as there’s no obvious way to dismantle it without major works.

DO NOT DO ANYTHING SILLY WITH THIS IDEA. I CAME UP WITH IT DURING MY LUNCH, HAVE PUT VERY LITTLE THOUGHT INTO IT, AND IT MAY WELL BE CRAP!!

[rsibbald 0]

Nice idea
As long as you spin away from the ball.....

I guess if the ball was mounted at the centre of spin it would not activate, and if the spin pushed the ball into your body it would not activate.

Which would mean ideally it should be helmet mounted in the centre, on top, assuming either your feet or your centre of hips are the point the spin is orientated around.


heh, I can imagine camera guys being reluctant to film if you mention you're gonna start swinging lead balls around if you go uncontrolled!

Cheers, I'll have a think about developing that....

[riggerrob 643]

The disadvantage with modern zero-stretch suspension lines (Spectra, Kevlar, HMA, etc.) is that they transmit loads at thousands of feet per second. Chances are your neck would be broken before the computer figured out what was going on.
A much simpler solution would be to build a weak link into the risers that failed at X pounds of pressure. The disadvantage of weak links is their short service life.

[RogerRamjet 0]

Well, if it's a sky surf board thing, you might look at the water-ski hard boot systems in use today. They attach to the ski with a pin at each end and an adjustable spring loaded release (sort of a ball bearing on a spring thing). They can be set to release at various tensions.

I think some snow ski boots attach in a similar way, but I am thinking of a dual boot setup and I've only seen that on water-ski setups.

You might have to figure a way to keep it from releasing on deployment, but I think you mentioned you want to release it before deploying anyway.

If you want to pursue something along that line, I can provide a link to get you started.

-----------------------
Roger "Ramjet" Clark
FB# 271, SCR 3245, SCS 1519

[JohnGraham 0]

Quote

The disadvantage with modern zero-stretch suspension lines (Spectra, Kevlar, HMA, etc.) is that they transmit loads at thousands of feet per second. Chances are your neck would be broken before the computer figured out what was going on.
A much simpler solution would be to build a weak link into the risers that failed at X pounds of pressure. The disadvantage of weak links is their short service life.

I assume you're reffering to what I suggested? There were two incidents that I've heard about that made me think this would have been a good idea - Chris Martin under the Xaos-21 21, and somebody around the same time who got spun-up under a 107 so fast he lost conciousness - I believe the last jumper's canopy corrected itself, and he landed safely.
Of course this device would do little to save you if you're spinning so fast your neck is already broken, but it would do you some good if spinning fast enough for you to lose conciousness or have difficulty lifting your arms up to your handles.

[JohnGraham 0]

Having a CYPRES cutter around the white loop with a variable firing height and low firing speed that you could turn off after deployment would at least jettison a skysurf board if you were spun-up so fast you lost conciousness.
It would also give you a wake-up call if you lost altitude awareness and went too low below your planned deployment height!

[Kris 0]

An automatic device to cutaway my main has to be about the scariest device I can think of.

An unintentional AAD fire sucks bad enough. An unintentional automatic cutaway at, say....200' will pretty much ruin your day.

Sky, Muff Bro, Rodriguez Bro, and
Bastion of Purity and Innocence!™

[mr2mk1g 10]

The only place I see it having a use are on these tiny experimental canopies where they're jetisoned above 2k anyway and jumped on a three canopy rig.

[mr2mk1g 10]

Would have to be a student cypres as in the past an expert model failed to fire during a high G spin - it was thought the spinning board generated enough lift to keep the decent speed lower than 78mph.

Student cypres though would mean no swooping or even agressive canopy manouvers under many canopies.

[rsibbald 0]

Roger, I'd be interested if you could either post that link you mentioned on here or PM me with it? IT sounds like an ideal system.

Another idea I was throwing around in my head was a very small PC, small enough to be collapsed inside your hand. Therefore if you fall unconscious and release it, the PC will pull the cable from the cutaway mechanism. I can see lots of problems regarding entaglements with this though.

[tkhayes 348]

Start by buying a larger, less radical canopy. One that opens smooth and not hard enough to knock you out. Buy a good rig, maintain it to better-than-manufacturer recommendations....

then use your brain and hands.

TK

[mr2mk1g 10]

You gonna come out with what you're actually thinking of doing? It's kinda like a HP canopy but not quite, and kinda like a skysurf board but not quite, can cause you to spin and is always cutaway before deployment... sounds interesting
Ever wonder if not doing it is the best option?

[RogerRamjet 0]

Quote

Roger, I'd be interested if you could either post that link you mentioned on here or PM me with it? IT sounds like an ideal system.

Another idea I was throwing around in my head was a very small PC, small enough to be collapsed inside your hand. Therefore if you fall unconscious and release it, the PC will pull the cable from the cutaway mechanism. I can see lots of problems regarding entaglements with this though.

Link to Fogman Bindings: http://www.fogmanbindings.com/products.html

-----------------------
Roger "Ramjet" Clark
FB# 271, SCR 3245, SCS 1519

[Spizzzarko 0]

How about enough weight built into the cutaway pillow, that it will overcome the velcro forces at a certain g loading. It should be a simple math equation.