Forums: Skydiving: Gear and Rigging:
AAD mode for dealing with fast spinning canopies?

 


377  (F 666)

Apr 14, 2008, 4:05 PM
Post #1 of 8 (835 views)
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AAD mode for dealing with fast spinning canopies? Can't Post

I have read several fatality reports where a jumper went in under a fast spinning canopy with no AAD fire. Descent was too slow to fire the AAD, but too fast to permit a survivable landing. How about adding a force sensor and software that would sense a prolonged constant high centrif. force below a certain altiude and fire? I know you'd have to figure out ways to avoid having it fire in an intentional high speed turn, but maybe someone can figure it out.


(This post was edited by 377 on Apr 14, 2008, 4:06 PM)


Premier billvon  (D 16479)
Moderator
Apr 14, 2008, 5:38 PM
Post #2 of 8 (796 views)
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Re: [377] AAD mode for dealing with fast spinning canopies? [In reply to] Can't Post

>How about adding a force sensor . . .

Or a light sensor to detect the increase in light when the main container opens. Or an accelerometer to detect canopy opening to help reduce low-pull fires. Or a system that would detect a high rate spin, fire cutters to cut the main away, then fire a cutter to open the reserve. (Prototype cypreses actually had a second firing circuit to allow that sort of operation.)

All perhaps good ideas, but so far the KISS principle seems to be working with AAD's. They do only one simple task and generally do it pretty well. Adding modes/sensors increases complexity and greatly increases the odds of unexpected operation.

(Not to say it can't be done, but that's the primary reason it hasn't been.)


377  (F 666)

Apr 14, 2008, 6:09 PM
Post #3 of 8 (780 views)
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Re: [billvon] AAD mode for dealing with fast spinning canopies? [In reply to] Can't Post

I do see your point Bill. I guess every new sensor or algorithm introduces a new misfire or no fire possibility.

At one WFFC I spoke to the SSK guys. They told me the Cypres 1 actually had unused parts of hardware and software that were originally designed to interface with the cutaway system. KISS won out.

As far as KISS goes, nothing could have been simpler than the SSE Sentinel Mk 2000 AAD. No software, no semiconductors, nothing more than two AA batteries, a cartridge, and a rate switch in series with an altitude switch. If below X and falling faster than Y, circuit to explosive cartridge completed and pin puller extracts reserve pin. Probably was OK for belly flying and round canopies.


fcajump  (D 15598)

Apr 15, 2008, 5:48 AM
Post #4 of 8 (690 views)
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Re: [377] AAD mode for dealing with fast spinning canopies? [In reply to] Can't Post

In reply to:
I do see your point Bill. I guess every new sensor or algorithm introduces a new misfire or no fire possibility.

At one WFFC I spoke to the SSK guys. They told me the Cypres 1 actually had unused parts of hardware and software that were originally designed to interface with the cutaway system. KISS won out.

As far as KISS goes, nothing could have been simpler than the SSE Sentinel Mk 2000 AAD. No software, no semiconductors, nothing more than two AA batteries, a cartridge, and a rate switch in series with an altitude switch. If below X and falling faster than Y, circuit to explosive cartridge completed and pin puller extracts reserve pin. Probably was OK for belly flying and round canopies.

In all things - balance -... even in simplicity.

Even earlier AADs (AODs) kept it even simpler, no rate sensor... of course your students had to remember to disarm it after opening...

I think Cypres has the balance just about right for the sport market.

JW


377  (F 666)

Apr 15, 2008, 10:17 AM
Post #5 of 8 (625 views)
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Re: [fcajump] AAD mode for dealing with fast spinning canopies? [In reply to] Can't Post

I remember those Sentinels. A real income provider for riggers as MANY students forgot to turn them off after opening. I never did, couldn't afford to back then.


erdnarob  (D 364)

Apr 15, 2008, 1:27 PM
Post #6 of 8 (564 views)
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Re: [377] AAD mode for dealing with fast spinning canopies? [In reply to] Can't Post

When you have a fast spinning canopy, the last thing you want is to have the AAD firing and getting your reserve deployed and get possibly an entanglement between the main and the reserve.
Your best move would be a cut away and a reserve deployment. If you have a SKYHOOK equiped Vector (Javelin has the option too), it's even better for you since when you cut away the SKYHOOK will have your reserve deployed quite faster than your pilot chute can do, and in a clean way even in fast spinning malfunction. Have a look at United Parachute Technologies (UPT) SKYHOOK demo DVD, it's very convincing.


377  (F 666)

Apr 15, 2008, 2:28 PM
Post #7 of 8 (546 views)
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Re: [erdnarob] AAD mode for dealing with fast spinning canopies? [In reply to] Can't Post

I was proposing something to help prevent those fatalities where the jumper is incapacitated by the spin forces and cannot cut away. Some jumpers with small canopies have goine in unconscious in high rate spins. Maybe deploying a reserve with an AAD would be risky but it is better than a certain fatal impact if nothing is done.

I am a big fan of Skyhooks after seeing some SCARY low low intentional Skyhook cutaway demos at WFFC. Man they got an open reserve F A S T!! I swear they were less than 300 ft when they cutaway. Just wish Skyhooks were approved for Eclipse and Reflex, which unfortunately will never happen as mfrs are out of business.


(This post was edited by 377 on Apr 15, 2008, 4:34 PM)


erdnarob  (D 364)

Apr 15, 2008, 9:41 PM
Post #8 of 8 (496 views)
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Re: [377] AAD mode for dealing with fast spinning canopies? [In reply to] Can't Post

Thanks to bring up the possibility to become knocked out by the G forces. That's why in case of a spinning malfuction, you should react as soon as possible and do a cut away. It's also a good idea to have your risers equiped with cable channel when the spin of the canopy induces heavy line twists. Those channels will keep free the cut away release cables.



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